Publications by authors named "Paul G Higgins"

101 Publications

Delineation of a novel environmental phylogroup of the genus Acinetobacter encompassing Acinetobacter terrae sp. nov., Acinetobacter terrestris sp. nov. and three other tentative species.

Syst Appl Microbiol 2021 May 24;44(4):126217. Epub 2021 May 24.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelstrasse 19-21 50935 Cologne, and German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany.

This study aimed to define the taxonomic position and structure of a novel, taxonomically unique group of 26 Acinetobacter strains, provisionally designated Taxon 24 (T24). The strains were recovered from soil and freshwater ecosystems (n = 21) or animals (n = 5) in Czechia, Scotland, Germany, the Netherlands and Turkey between 1993 and 2015. They were non-glucose-acidifying, nonhemolytic, nonproteolytic, growing at 32 °C and on acetate and ethanol as single carbon sources, but not on 4-hydroxybenzoate and mostly not at 37 °C. Their whole-genome sequences were 3.0-3.7 Mb in size, with GC contents of 39.8-41.3%. Based on core genome phylogenetic analysis, the 26 strains formed a distinct clade within the genus Acinetobacter, with strongly supported subclades termed T24A (n = 11), T24B (n = 8), T24C (n = 2), T24D (n = 3) and T24E (n = 2). The internal genomic ANIb values for these subclades were >94.8%, while the ANIb values between them were <92.5%. The results of MALDI-TOF MS-based analyses agreed with this classification. The five subclades differed from each other in the results of one to six carbon source assimilation tests. Given the genomic and phenotypic distinctness, internal coherence, numbers of available strains and geographically diverse origin of T24A and T24B, we propose the names Acinetobacter terrae sp. nov. and Acinetobacter terrestris sp. nov. for these two taxa, respectively. The type strains are ANC 4282 (= CCM 8986 = CCUG 73811 = CNCTC 8082) and ANC 4471 (= CCM 8985 = CCUG 73812 = CNCTC 8093), respectively. We conclude that these two species together with the other T24 strains represent a widely dispersed Acinetobacter clade primarily associated with terrestrial ecosystems.
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http://dx.doi.org/10.1016/j.syapm.2021.126217DOI Listing
May 2021

Diversity of sequence types and impact of fitness cost among carbapenem-resistant isolates from Tripoli, Libya.

Antimicrob Agents Chemother 2021 Jun 7:AAC0027721. Epub 2021 Jun 7.

Institute for Medical Microbiology, Immunology and Hygiene, University of Colognegrid.6190.e, Germany.

We investigated the molecular epidemiology of 21 carbapenem-resistant from Libya, and assessed their relative fitness. Core-genome MLST revealed five inter-hospital transmission clusters. Three clusters were associated with the international clones (IC) IC1, IC2, and IC7. Carbapenem-resistance was associated with , or . Compared to DSM 30008, the doubling time was similar over 10 hours, but after 16 hours, half the isolates grew to higher densities, suggesting a fitness advantage.
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http://dx.doi.org/10.1128/AAC.00277-21DOI Listing
June 2021

Fecal microbiota transfer for refractory intestinal graft-versus-host disease - Experience from two German tertiary centers.

Eur J Haematol 2021 May 2. Epub 2021 May 2.

German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Germany.

Rationale: Steroid refractory graft-vs-host disease (sr-GvHD) represents a challenging complication after allogeneic hematopoietic cell transplantation (allo-HCT). Intestinal microbiota (IM) diversity and dysbiosis were identified as influencing factors for the development of acute GvHD. Fecal microbiota transfer (FMT) is hypothesized to restore IM dysbiosis, but there is limited knowledge about the significance of FMT in the treatment of sr-GvHD.

Objectives: We studied the effects of FMT on sr-GvHD in allo-HCT patients from two German tertiary clinical centers (n = 11 patients; period: March 2017 until July 2019). To assess safety and clinical efficacy, we analyzed clinical data pre- and post-FMT (day -14 to +30 relative to FMT). Moreover, IM were analyzed in donor samples and in a subset of patients pre- and post-FMT by 16S rRNA sequencing.

Results: Post-FMT, we observed no intervention-associated, systemic inflammatory responses and only minor side effects (5/11 patients: abdominal pain and transformation of peristalsis-each 3/11 and vomiting-1/11). Stool frequencies and volumes were significantly reduced [pre- vs post-FMT (d14): P < .05, respectively] as well as clear attenuation regarding both grading and staging of sr-GvHD was present upon FMT. Moreover, IM analyses revealed an increase of alpha diversity as well as a compositional shifts toward the donor post-FMT.

Conclusions: In our study, we observed positive effects on sr-GVHD after FMT without the occurrence of major adverse events. Although these findings are in line with published data on beneficial effects of FMT in sr-GvHD, further randomized clinical studies are urgently needed to better define the clinical validity including mode of action.
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http://dx.doi.org/10.1111/ejh.13642DOI Listing
May 2021

Molecular Epidemiology of Carbapenem-Resistant Isolates from Northern Africa and the Middle East.

Antibiotics (Basel) 2021 Mar 11;10(3). Epub 2021 Mar 11.

Department of Hospital Hygiene & Infectious Diseases, University Medicine Goettingen, 37075 Göttingen, Germany.

At the Bundeswehr Hospitals of Hamburg and Westerstede, patients repatriated from subtropical war and crisis zones of Northern Africa and the Middle East were medically treated, including microbiological assessment. Within a six-year interval, 16 spp. strains, including 14 (Ab) isolates with resistance against carbapenems and origins in Afghanistan ( = 4), Iraq ( = 2), Libya ( = 2), and Syria ( = 8) were collected. While clonal relationships of Libyan and Syrian strains had been assessed by superficial next generation sequencing (NGS) and "DiversiLab" repetitive elements sequence-based (rep-)PCR so far, this study provides core genome-based sequence typing and thus more detailed epidemiological information. In detail, sequencing allowed a definitive species identification and comparison with international outbreak-associated Ab strains by core genome multi locus sequence typing (cgMLST) and the identification of MLST lineages, as well as the identification of known resistance genes. The sequence analysis allowed for the confirmation of outbreak-associated clonal clusters among the Syrian and Afghan Ab isolates, indicating likely transmission events. The identified acquired carbapenem resistance genes comprised , , , and , next to other intrinsic and acquired, partly mobile resistance-associated genes. Eleven out of 14 Ab isolates clustered with the previously described international clonal lineages IC1 (4 Afghan strains), IC2 (6 Syrian strains), and IC7 (1 Syrian strain). Identified Pasteur sequence types of the 14 Ab strains comprised ST2 (Syrian), ST25 (Libyan), ST32 (Iraqi), ST81 (Afghan), ST85 (Libyan), and ST1112 (Syrian), respectively. In conclusion, the study revealed a broad spectrum of resistance genes in Ab isolated from war-injured patients from Northern Africa and the Middle East, thereby broadening the scarcely available data on locally abundant clonal lineages and resistance mechanisms.
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http://dx.doi.org/10.3390/antibiotics10030291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002098PMC
March 2021

Prevalence of RND efflux pump regulator variants associated with tigecycline resistance in carbapenem-resistant Acinetobacter baumannii from a worldwide survey.

J Antimicrob Chemother 2021 Mar 24. Epub 2021 Mar 24.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.

Objectives: To determine the most common tigecycline resistance mechanisms in carbapenem-resistant Acinetobacter baumannii isolates obtained during the global Tigecycline Evaluation Surveillance Trial (TEST).

Methods: Tigecycline MICs were determined by broth microdilution. WGS was used to screen for the previously identified tigecycline resistance mechanisms, as well as mutations in resistance-nodulation-cell division (RND)-type efflux pump regulators.

Results: From a total 313 isolates, 113 genetically unique tigecycline-resistant isolates were analysed. The most frequent and worldwide distributed mechanism associated with tigecycline resistance was disruption of adeN, which encodes the repressor of the RND efflux pump AdeIJK, either by IS elements or nucleotide deletions causing premature stop codons. However, mutations leading to amino acid substitutions and disruption by IS elements within the two-component regulatory system adeRS, which regulates expression of the AdeABC efflux pump, correlate with higher tigecycline MICs, but these were found less frequently and were mainly restricted to Southern European countries. Furthermore, an altered version of tviB was identified in several tigecycline-resistant isolates that did not have putative resistance mutations within RND-type regulators. The resistance determinants tet(A) and tet(X), as well as resistance mutations in putative resistance determinants trm, plsC, rrf, msbA and genes encoding 30S ribosomal proteins, were not identified in any isolate.

Conclusions: The most prevalent tigecycline resistance mechanisms were caused by alterations in the regulators of RND-type efflux pumps. These data provide the basis for further characterization of regulator alterations and their contribution to increased efflux and tigecycline resistance, and also should be taken into account in drug discovery programmes to overcome the contribution of efflux pumps.
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http://dx.doi.org/10.1093/jac/dkab079DOI Listing
March 2021

Molecular Epidemiology of Carbapenem-Resistant From Khartoum State, Sudan.

Front Microbiol 2021 26;12:628736. Epub 2021 Feb 26.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.

Carbapenem resistant (CRAb) is an important global pathogen contributing to increased morbidity and mortality in hospitalized patients, due to limited alternative treatment options. Nine international clonal (IC) lineages have been identified in many countries worldwide, however, data still lacks from some parts of the world, particularly in Africa. We hereby present the molecular epidemiology of MDR from four hospitals in Khartoum, Sudan, collected from 2017 to 2018. Forty-two isolates were whole-genome sequenced, and subsequent molecular epidemiology was determined by core genome MLST (cgMLST), and their resistomes identified. All isolates had an array of diverse antibiotic resistance mechanisms conferring resistance to multiple classes of antibiotics. We found a predominance (88%) of IC2 (with the intrinsic OXA-66 and acquired OXA-23), and some with NDM-1. IC2 isolates were sub-divided into 4 STs separated by 5 to 431 allelic differences, and with evidence of seven transmission clusters. Isolates belonging to IC1, IC5, and IC9 were also identified. These data illustrate that MDR IC2 are widely distributed in Khartoum hospitals and are in possession of multiple antibiotic resistance determinants.
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http://dx.doi.org/10.3389/fmicb.2021.628736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7952628PMC
February 2021

Epitope-specific immunity against Staphylococcus aureus coproporphyrinogen III oxidase.

NPJ Vaccines 2021 Jan 18;6(1):11. Epub 2021 Jan 18.

Institute for Medical Microbiology, Immunology and Hygiene, University Hospital Cologne, Cologne, Germany.

Staphylococcus aureus represents a serious infectious threat to global public health and a vaccine against S. aureus represents an unmet medical need. We here characterise two S. aureus vaccine candidates, coproporphyrinogen III oxidase (CgoX) and triose phosphate isomerase (TPI), which fulfil essential housekeeping functions in heme synthesis and glycolysis, respectively. Immunisation with rCgoX and rTPI elicited protective immunity against S. aureus bacteremia. Two monoclonal antibodies (mAb), CgoX-D3 and TPI-H8, raised against CgoX and TPI, efficiently provided protection against S. aureus infection. MAb-CgoX-D3 recognised a linear epitope spanning 12 amino acids (aa), whereas TPI-H8 recognised a larger discontinuous epitope. The CgoX-D3 epitope conjugated to BSA elicited a strong, protective immune response against S. aureus infection. The CgoX-D3 epitope is highly conserved in clinical S. aureus isolates, indicating its potential wide usability against S. aureus infection. These data suggest that immunofocusing through epitope-based immunisation constitutes a strategy for the development of a S. aureus vaccine with greater efficacy and better safety profile.
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http://dx.doi.org/10.1038/s41541-020-00268-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7813823PMC
January 2021

Novel multiplex PCRs for detection of the most prevalent carbapenemase genes in Gram-negative bacteria within Germany.

J Med Microbiol 2021 Mar 15;70(3). Epub 2021 Jan 15.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, 50923 Köln, Germany.

Gram-negative bacteria are a common source of infection both in hospitals and in the community, and antimicrobial resistance is frequent among them, making antibiotic therapy difficult, especially when these isolates carry carbapenem resistance determinants.. A simple method to detect all the commonly found carbapenemases in Germany was not available. The aim of this study was to develop a multiplex PCR for the rapid and reliable identification of the most prevalent carbapenemase-encoding genes in Gram-negative bacteria in Germany. Data from the German Gram-negative reference laboratory revealed the most prevalent carbapenemase groups in Germany were (in order of prevalence): , , , , , , , , , , IS, , and . We developed and tested two multiplex PCRs against 83 carbapenem-resistant Gram-negative clinical isolates. Primers were designed for each carbapenemase group within conserved regions of the encoding genes obtained from publicly available databases. Multiplex-1 included the carbapenemase groups , , , , and , while multiplex-2 included , , , , IS and . In the initial evaluation, all but one of the carbapenemases encoded by 75 carbapenemase-positive isolates were detected using the two multiplex PCRs, while no false-positive results were obtained from the remaining eight isolates. After evaluation, we tested 546 carbapenem-resistant isolates using the multiplex PCRs, and all carbapenemases were detected. A rapid and reliable method was developed for detection and differentiation of 12 of the most prevalent carbapenemase groups found in Germany. This method allows for the rapid testing of clinical isolates prior to species identification and does not require prior phenotypical characterization, constituting a rapid and valuable tool in the management of infections in hospitals.
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http://dx.doi.org/10.1099/jmm.0.001310DOI Listing
March 2021

Characterization of a vancomycin-resistant Enterococcus faecium isolate and a vancomycin-susceptible E. faecium isolate from the same blood culture.

J Antimicrob Chemother 2021 Mar;76(4):883-886

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.

Objectives: To characterize two Enterococcus faecium isolates with different resistance phenotypes obtained from the same blood culture.

Methods: The isolates were identified by MALDI-TOF MS and antimicrobial susceptibility testing (AST) was performed using a VITEK® 2 AST P592 card and Etest. WGS was performed on the MiSeq and MinION sequencer platforms. Core-genome MLST (cgMLST) and seven-loci MLST were performed. Plasmid analysis was performed using S1-PFGE followed by Southern-blot hybridization.

Results: Both E. faecium isolates were ST203. AST revealed that one was a vancomycin-resistant E. faecium (VREfm) isolate and the other was a vancomycin-susceptible E. faecium (VSEfm) isolate. The VREfm isolate harboured the vanA gene cluster as part of a Tn1546-type transposon encoded on a 49 kb multireplicon (rep1, rep2 and rep7a) plasmid (pAML0157.1). On the same plasmid, ant(6)-Ia, cat-like and erm(B) were encoded. The VSEfm isolate harboured a rep2 plasmid (pAML0158.1), 12 kb in size, which was present in full length as part of pAML0157.1 from the VREfm isolate. The vanA-encoding pAML0157.1 was a chimera of the rep2 pAML0158.1 and a second DNA segment harbouring vanA, ant(6)-Ia, erm(B) and cat-like, as well as the replicons rep1 and rep7a. By cgMLST analysis, the VREfm and VSEfm isolates were identical.

Conclusions: Our results demonstrate that the VREfm and VSEfm blood culture isolates represented ST203 and were identical. The investigated heterogeneous resistance phenotypes resulted from the acquisition or loss of plasmid segments in the enterococcal isolates. These data illustrate that mobile genetic elements may contribute to the spread of vancomycin resistance among enterococci and to the genotypic and phenotypic variation within clonal isolates.
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http://dx.doi.org/10.1093/jac/dkaa532DOI Listing
March 2021

Molecular Characterization of Carbapenem/Colistin-Resistant Clinical Isolates from Egypt by Whole-Genome Sequencing.

Infect Drug Resist 2020 16;13:4487-4493. Epub 2020 Dec 16.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne 50935, Germany.

Purpose: The rise of carbapenem-resistant (CRAB) is considered a public health problem limiting the treatment options. Our current work studied the emergence and mechanisms of colistin-resistance among CRAB isolates in Egypt.

Materials And Methods: Seventeen clinically recovered were identified and screened for their antimicrobial susceptibilities using VITEK-2 system. Colistin susceptibility was evaluated using broth microdilution, and characterization of carbapenem/colistin resistance determinants was performed using whole-genome sequencing (Illumina MiSeq).

Results: About 52.9% (9/17) were colistin-resistant. PCR results revealed that all isolates carried , was detected in 82.3% (14/17) and in 23.5% (4/17). Two isolates harboured and . Furthermore, genome analysis of seven isolates revealed six belonged to international clone 2 (IC2) while the remaining isolate was a singleton (ST158), representing a clone circulating in Mediterranean/Middle Eastern countries.

Conclusion: The emergence and high incidence of colistin-resistance among CRAB clinical isolates in Egypt are alarming because it further limits therapy options and requires prudent antimicrobial stewardship and stringent infection control measures. Whole-genome sequence analyses suggest that the resistance to colistin was associated with multiple mutations in the genes. The high incidence of the high-risk lineage IC2 harbouring as well as is also of concern.
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http://dx.doi.org/10.2147/IDR.S288865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7751577PMC
December 2020

Genomic Analysis of Carbapenem-Resistant Isolates Belonging to Major Endemic Clones in South America.

Front Microbiol 2020 30;11:584603. Epub 2020 Nov 30.

Universidade Federal de São Paulo (UNIFESP), Laboratório Alerta, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil.

Carbapenem-resistant (CRAB) are emerging worldwide. In South America, clinical isolates presenting such a phenotype usually do not belong to the globally distributed international clone 2 (IC2). The majority of these isolates are also resistant to multiple other antimicrobials and are often designated extremely drug-resistant (XDR). The aim of this study was to characterize the resistance mechanisms presented by 18 carbapenem-resistant isolates from five different Brazilian hospitals. Species identification was determined by sequencing, and antimicrobial susceptibility was determined by broth microdilution. Isolates were submitted to whole genome sequencing using Illumina platform and genetic similarity was determined by PFGE, MLST, and cgMLST. Genome analysis was used to identify intrinsic and acquired resistance determinants, including mutations in the AdeRSABC efflux system and in outer membrane proteins (OMPs). All isolates were identified as and grouped into 4 pulsotypes by PFGE, which belonged to clonal complexes (CC) 15 /103 ( = 4) and 79 /113 ( = 14), corresponding to IC4 and IC5, respectively. High MIC values to carbapenems, broad-spectrum cephalosporins, amikacin, and ciprofloxacin were observed in all isolates, while MICs of ampicillin/sulbactam, gentamicin, and tigecycline varied among the isolates. Minocycline was the most active antimicrobial agent tested. Moreover, 12 isolates (66.7%) were considered resistant to polymyxins. Besides intrinsic OXA-51 and ADC variants, all isolates harbored an acquired carbapenem-hydrolyzing class D β-lactamase (CHDL) encoding gene, either or . A diversity of aminoglycoside modifying enzymes and resistance determinants to other antimicrobial classes were found, as well as mutations in and . Non-synonymous mutations have also been identified in the AdeRSABC efflux system and in most OMPs, but they were considered natural polymorphisms. Moreover, resistance to polymyxins among isolates belonging to IC5 were associated to non-synonymous mutations in , but no known polymyxin resistance mechanism was identified in isolates belonging to IC4. In conclusion, clinical isolates belonging to South America's major clones present a myriad of antimicrobial resistance determinants. Special attention should be paid to natural polymorphisms observed in each clonal lineage, especially regarding non-synonymous mutations in constitutive genes associated with distinct resistance phenotypes.
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http://dx.doi.org/10.3389/fmicb.2020.584603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7734285PMC
November 2020

Rescued chlorhexidine activity by resveratrol against carbapenem-resistant Acinetobacter baumannii via down-regulation of AdeB efflux pump.

PLoS One 2020 2;15(12):e0243082. Epub 2020 Dec 2.

Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

The aim of this study was to determine the activity and synergistic mechanisms of resveratrol in combination with chlorhexidine against carbapenem-resistant Acinetobacter baumannii clinical isolates. The activity of resveratrol plus antimicrobial agents was determined by checkerboard and time-kill assay against carbapenem-resistant A. baumannii isolated from patients at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Overexpression of efflux pumps that mediates chlorhexidine susceptibility was characterized by the ethidium bromide accumulation assay. The effect of resveratrol on the expression of efflux pump genes (adeB, adeJ, adeG abeS, and aceI) and the two-component regulators, adeR and adeS was determined by RT-qPCR. The combination of resveratrol and chlorhexidine resulted in strong synergistic and bactericidal activity against carbapenem-resistant A. baumannii. Up-regulation of adeB and aceI was induced by chlorhexidine. However, the addition of resveratrol increased chlorhexidine susceptibility with increased intracellular accumulation of ethidium bromide in A. baumannii indicating that resveratrol acts as an efflux pump inhibitor. Expression of adeB was significantly reduced in the combination of resveratrol with chlorhexidine indicating that resveratrol inhibits the AdeB efflux pump and restores chlorhexidine effect on A. baumannii. In conclusion, reduced adeB expression in A. baumannii was mediated by resveratrol suggesting that AdeB efflux pump inhibition contributes to the synergistic mechanism of resveratrol with chlorhexidine. Our finding highlights the potential importance of resveratrol in clinical applications.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0243082PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7710055PMC
January 2021

A comprehensive and contemporary "snapshot" of β-lactamases in carbapenem resistant Acinetobacter baumannii.

Diagn Microbiol Infect Dis 2021 Feb 16;99(2):115242. Epub 2020 Oct 16.

Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, USA; Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA; Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, USA; Departments of Biochemistry, Pharmacology, and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, USA; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES) Cleveland, OH, USA. Electronic address:

Successful treatment of Acinetobacter baumannii infections require early and appropriate antimicrobial therapy. One of the first steps in this process is understanding which β-lactamase (bla) alleles are present and in what combinations. Thus, we performed WGS on 98 carbapenem-resistant A. baumannii (CR Ab). In most isolates, an acquired bla carbapenemase was found in addition to the intrinsic bla allele. The most commonly found allele was bla (n = 78/98). In some isolates, bla was found in addition to other carbapenemase alleles: bla (n = 12/78), bla (n = 2/78) and bla (n = 1/78). Surprisingly, 20% of isolates carried carbapenemases not routinely assayed for by rapid molecular diagnostic platforms, i.e., bla and bla; all had ISAba1 elements. In 8 CR Ab, bla or bla was the only carbapenemase. Both bla and its variant bla were each found in 6/98 isolates. The most prevalent ADC variants were bla (21%), bla (21%), and bla (26%). Complete combinations are reported.
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http://dx.doi.org/10.1016/j.diagmicrobio.2020.115242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7562987PMC
February 2021

First Report of New Delhi Metallo--Lactamase-6 (NDM-6) in a Clinical Isolate From Northern Spain.

Front Microbiol 2020 10;11:589253. Epub 2020 Nov 10.

Department of Immunology, Microbiology, and Parasitology, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Bilbao, Spain.

The objective of this study was the phenotypic and genotypic characterization of a carbapenem resistant (CRAB) isolate. The isolate, recovered in Northern Spain in 2019, was identified by MALDI-TOF to the species level. Antimicrobial susceptibility testing was performed using the Phoenix BD NMIC-502 Panel, E-test, and broth microdilution methods. The presence of a metallo--lactamase (MBL) was verified by PCR and immunochromatographic assays. The genetic location of the MBL was confirmed using S1-pulsed-field gel electrophoresis (S1-PFGE) followed by Southern blot hybridization. Whole genome sequencing (WGS) was completed using the Miseq and MinION platforms, followed by core-genome MLST (cgMLST) and seven-locus MLST analysis. The CRAB was assigned ST85 (Pasteur scheme) and ST957 (Oxford scheme) representing international clone (IC) 9 and harbored the intrinsic -lactamase OXA-94 with IS upstream of it, and the MBL . Hybridization experiments revealed that the was encoded on the chromosome. Using WGS the environment could be identified arranged in the following order: IS, , IS, , , , , , and IS. Downstream, a 10,462 bp duplication was identified, including a second copy of in the following genetic composition: IS, , , , , , and IS. To our knowledge, this is the first description of in . The MBL was present in two copies in the chromosome in a new genetic environment associated with IS elements highlighting the contribution of mobile genetic elements in the dissemination of this gene.
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http://dx.doi.org/10.3389/fmicb.2020.589253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7683408PMC
November 2020

The distribution of mutations and hotspots in transcription regulators of resistance-nodulation-cell division efflux pumps in tigecycline non-susceptible Acinetobacter baumannii in China.

Int J Med Microbiol 2020 Dec 24;310(8):151464. Epub 2020 Oct 24.

Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China; Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China; Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China. Electronic address:

Objective: Acinetobacter baumannii has emerged as a problematic hospital pathogen and tigecycline is among the few remaining antibiotics retaining activity against multidrug-resistant A. baumannii. This study was aimed to elucidate the tigecycline resistance mechanisms in 28 unique clinical A. baumannii strains from nine provinces in China.

Methods: Whole genome sequences were obtained via Illumina HiSeq sequencing and regulatory genes of efflux pumps were analyzed. Minimal inhibitory concentrations (MICs) were determined by agar/microbroth dilution according to the guidelines recommended by Clinical and Laboratory Standards Institute (CLSI). Tigecycline susceptibility data was interpreted using breakpoints for Enterobacterales recommended by EUCAST v8.1.

Results: The majority of isolates belonged to the international clonal lineage IC2 (n = 27, 96.4%). Four isolates were considered tigecycline-intermediate (MIC = 2 mg/L), twenty-four isolates were tigecycline-resistant. The insertion of ISAba1 in adeS was found in six isolates and was the most prevalent insertion element (IS). In four isolates we observed an insertion of ISAba1 in adeN, and two of them had IS26 insertions. Two mutations in adeN (deletion and premature stop codon) were observed only in the MIC = 4 mg/L isolates. Other mutations in adeRS (amino acid insertion/substitutions and premature stop codons) were only detected in the MIC ≥ 8 group. The novel substitutions E219 K in adeR and A130 T in adeS were observed in five and four isolates respectively, suggesting a mutational hotspot.

Conclusions: This study demonstrates that changes in transcription regulators were important mechanisms in tigecycline resistance in A. baumannii. Also, we identified several chromosomal hotspots that can be used for prediction of tigecycline resistance.
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http://dx.doi.org/10.1016/j.ijmm.2020.151464DOI Listing
December 2020

Antibiotic Resistance and Mobile Genetic Elements in Extensively Drug-Resistant Sequence Type 147 Recovered from Germany.

Antibiotics (Basel) 2020 Oct 5;9(10). Epub 2020 Oct 5.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, 50935 Cologne, Germany.

Mobile genetic elements (MGEs), especially multidrug-resistance plasmids, are major vehicles for the dissemination of antimicrobial resistance determinants. Herein, we analyse the MGEs in three extensively drug-resistant (XDR) isolates from Germany. Whole genome sequencing (WGS) is performed using Illumina and MinION platforms followed by core-genome multi-locus sequence typing (MLST). The plasmid content is analysed by conjugation, S1-pulsed-field gel electrophoresis (S1-PFGE) and Southern blot experiments. The isolates belong to the international high-risk clone ST147 and form a cluster of closely related isolates. They harbour the carbapenemase on a ColKP3 plasmid, and 12 antibiotic resistance determinants on an multidrug-resistant (MDR) IncR plasmid with a recombinogenic nature and encoding a large number of insertion elements. The IncR plasmids within the three isolates share a high degree of homology, but present also genetic variations, such as inversion or deletion of genetic regions in close proximity to MGEs. In addition, six plasmids not harbouring any antibiotic resistance determinants are present in each isolate. Our study indicates that genetic variations can be observed within a cluster of closely related isolates, due to the dynamic nature of MGEs. The mobilome of the isolates combined with the emergence of the XDR ST147 high-risk clone have the potential to become a major challenge for global healthcare.
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http://dx.doi.org/10.3390/antibiotics9100675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600919PMC
October 2020

The TACTIC experience: establishing an international, interdisciplinary network to tackle antimicrobial resistance.

J Med Microbiol 2020 Oct 9;69(10):1213-1220. Epub 2020 Sep 9.

Brighton and Sussex Centre for Global Health Research, Department of Global Health and Infection, Brighton and Sussex Medical School, Brighton, BN1 9PX, UK.

Antimicrobial resistance (AMR) is a major global health threat that requires an interdisciplinary international approach to address. In response to calls from policymakers and funders alike, a growing number of research networks on AMR have been created with this approach in mind. However, there are many challenges facing researchers in establishing such networks and research projects. In this article, we share our experience of establishing the network 'TACTIC: Tackling AMR Challenges through Translational Interdisciplinary Collaborations'. Although presented with many challenges both scientific and logistical, the network has underpinned productive interaction between biomedical and social scientists from several countries and fostered true collaboration in an educative, stimulating and sustainable way that forms a platform for important research on AMR.
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http://dx.doi.org/10.1099/jmm.0.001249DOI Listing
October 2020

Molecular Epidemiology of Carbapenem-Resistant Isolated from War-Injured Patients from the Eastern Ukraine.

Antibiotics (Basel) 2020 Sep 5;9(9). Epub 2020 Sep 5.

Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, 18057 Rostock, Germany.

Recently, a total of 32 carbapenem- and fluoroquinolone-resistant (Ab) isolates was isolated from war-injured patients who were treated at German Bundeswehr Hospitals, and preliminarily typed by "DiversiLab" repetitive elements sequence-based (rep-) PCR. Core genome-based sequence typing was also used to provide more detailed epidemiological information. From the clusters observed by rep-PCR, selected Ab strains were subjected to Next Generation Sequencing (NGS) in order to compare them with international outbreak-associated Ab strains and to identify MLST (multi-locus sequence type) lineages, as well as to identify known resistance genes. Accordingly, NGS indicated higher diversity than rep-PCR, but also confirmed likely transmission events. The identified acquired carbapenem-resistant genes comprised , and , as well as various other intrinsic and acquired resistance-associated genetic elements. All isolates clustered with the previously identified international clonal lineages IC1, IC2, IC6 and IC7, with corresponding Pasteur sequence types ST1, ST2, ST78 and ST25, respectively. In conclusion, the assessment confirmed a broad spectrum of resistance-associated genes in Ab isolated from war-injured patients from the Eastern Ukraine, and provided the first insights into locally abundant clonal lineages.
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http://dx.doi.org/10.3390/antibiotics9090579DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558915PMC
September 2020

Vancomycin-resistant Enterococcus faecium colonizing patients on hospital admission in Germany: prevalence and molecular epidemiology.

J Antimicrob Chemother 2020 10;75(10):2743-2751

German Centre for Infection Research (DZIF), Braunschweig, Germany.

Objectives: To analyse the rectal carriage rate and the molecular epidemiology of vancomycin-resistant Enterococcus faecium (VREfm) recovered from patients upon hospital admission.

Methods: Adult patients were screened at six German university hospitals from five different federal states upon hospital admission for rectal colonization with VREfm between 2014 and 2018. Molecular characterization of VREfm was performed by WGS followed by MLST and core-genome MLST analysis.

Results: Of 16350 patients recruited, 263 were colonized with VREfm, with increasing prevalence rates during the 5 year study period (from 0.8% to 2.6%). In total, 78.5% of the VREfm were vanB positive and 20.2% vanA positive, while 1.2% harboured both vanA and vanB. The predominant ST was ST117 (56.7%) followed by ST80 (15%), ST203 (10.9%), ST78 (5.7%) and ST17 (3.2%). ST117/vanB VREfm isolates formed a large cluster of 96 closely related isolates extending across all six study centres and four smaller clusters comprising 13, 5, 4 and 3 isolates each. In contrast, among the other STs inter-regional clonal relatedness was rarely observed.

Conclusions: To our knowledge, this is the largest admission prevalence and molecular epidemiology study of VREfm. These data provide insight into the epidemiology of VREfm at six German university hospitals and demonstrate the remarkable inter-regional clonal expansion of the ST117/vanB VREfm clone.
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http://dx.doi.org/10.1093/jac/dkaa271DOI Listing
October 2020

In vitro activity of sulbactam/durlobactam against global isolates of carbapenem-resistant Acinetobacter baumannii.

J Antimicrob Chemother 2020 09;75(9):2616-2621

Antiinfectives Intelligence GmbH, Rheinbach, Germany.

Objectives: To evaluate the activity of the novel broad-spectrum serine β-lactamase inhibitor durlobactam (ETX2514) combined with sulbactam against global isolates of carbapenem-resistant Acinetobacter baumannii with defined carbapenem resistance mechanisms compared with reference antimicrobials with known activity against Acinetobacter spp.

Methods: The susceptibility of 246 carbapenem-resistant non-duplicate A. baumannii isolates to sulbactam/durlobactam, amikacin, colistin, imipenem/sulbactam/durlobactam, imipenem, meropenem, minocycline and sulbactam was tested using broth microdilution. Isolates were obtained from various body sites from patients in 37 countries and from six world regions between 2012 and 2016. Identification of carbapenem resistance mechanisms and assignment to A. baumannii clonal lineages was based on WGS.

Results: Sulbactam/durlobactam showed excellent activity comparable to colistin but superior to amikacin, minocycline and sulbactam. The sulbactam/durlobactam MIC50/90 values were 1/4 and 2/4 mg/L and the colistin MIC50/90 values were 0.5 and 1 mg/L, respectively. Comparatively, amikacin, minocycline and sulbactam MIC50/90 values were 256/≥512, 2/16 and 16/64 mg/L, respectively.

Conclusions: Sulbactam/durlobactam had excellent in vitro potency against A. baumannii isolates, including those that were resistant to imipenem/meropenem, amikacin, minocycline and colistin, compared with other compounds. Sulbactam/durlobactam has the potential to become a useful addition to the limited armamentarium of drugs that can be used to treat this problem pathogen.
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http://dx.doi.org/10.1093/jac/dkaa208DOI Listing
September 2020

Mobile Genetic Elements Harboring Antibiotic Resistance Determinants in Isolates From Bolivia.

Front Microbiol 2020 13;11:919. Epub 2020 May 13.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.

Using a combination of short- and long-read DNA sequencing, we have investigated the location of antibiotic resistance genes and characterized mobile genetic elements (MGEs) in three clinical multi-drug resistant . The isolates, collected in Bolivia, clustered separately with three different international clonal lineages. We found a diverse array of transposons, plasmids and resistance islands related to different insertion sequence (IS) elements, which were located in both the chromosome and in plasmids, which conferred resistance to multiple antimicrobials, including carbapenems. Carbapenem resistance might be caused by a carrying the gene. Some plasmids were shared between the isolates. Larger plasmids were less conserved than smaller ones and they shared some homologous regions, while others were more diverse, suggesting that these big plasmids are more plastic than the smaller ones. The genetic basis of antimicrobial resistance in Bolivia has not been deeply studied until now, and the mobilome of these isolates, combined with their multi-drug resistant phenotype, mirror the transfer and prevalence of MGEs contributing to the spread of antibiotic resistance worldwide and require special attention. These findings could be useful to understand the antimicrobial resistance genetics of in Bolivia and the difficulty in tackling these infections.
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http://dx.doi.org/10.3389/fmicb.2020.00919DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237729PMC
May 2020

causing nosocomial transmission among neonates - an emerging pathogen?

J Med Microbiol 2020 Mar;69(3):396-401

German Center for Infection Research (DZIF), Partner site Bonn-Cologne, Germany.

Transmission of Enterobacterales in neonatal intensive care units (NICU) can cause outbreaks of colonization and invasive infections among neonates. Two clusters of nosocomial transmission of identified by MALDI-ToF mass-spectrometry were suspected at two NICUs in July and August 2016. To assess the potential transmission of among neonates. Whole-genome sequencing (WGS) was performed of isolates obtained through targeted surveillance of patients and environmental sampling. WGS data revealed that patient and environmental isolates represented two species, and . Core-genome multi-locus sequence typing (cgMLST) of the isolates identified three separate transmission clusters, in Hospital A a cluster of isolates in 12 children and two environmental samples and a second cluster of isolates in five children. In Hospital B a cluster of isolates from three children and five unrelated isolates of and two unrelated isolates of were found. can cause hospital outbreaks of colonization and infection similar to other spp.Preliminary results from this study were presented at the 27th European Congress of Clinical Microbiology and Infectious Diseases, April 22-25, 2018, Vienna, Austria.
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http://dx.doi.org/10.1099/jmm.0.001143DOI Listing
March 2020

Heavy Metal Toxicity in Armed Conflicts Potentiates AMR in by Selecting for Antibiotic and Heavy Metal Co-resistance Mechanisms.

Front Microbiol 2020 3;11:68. Epub 2020 Feb 3.

Department of Experimental Pathology, Immunology and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.

has become increasingly resistant to leading antimicrobial agents since the 1970s. Increased resistance appears linked to armed conflicts, notably since widespread media stories amplified clinical reports in the wake of the American invasion of Iraq in 2003. Antimicrobial resistance is usually assumed to arise through selection pressure exerted by antimicrobial treatment, particularly where treatment is inadequate, as in the case of low dosing, substandard antimicrobial agents, or shortened treatment course. Recently attention has focused on an emerging pathogen, multi-drug resistant (MDRAb). MDRAb gained media attention after being identified in American soldiers returning from Iraq and treated in US military facilities, where it was termed "Iraqibacter." However, MDRAb is strongly associated in the literature with war injuries that are heavily contaminated by both environmental debris and shrapnel from weapons. Both may harbor substantial amounts of toxic heavy metals. Interestingly, heavy metals are known to also select for antimicrobial resistance. In this review we highlight the potential causes of antimicrobial resistance by heavy metals, with a focus on its emergence in in war zones.
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http://dx.doi.org/10.3389/fmicb.2020.00068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7008767PMC
February 2020

Molecular surveillance of carbapenemase-producing at three medical centres in Cologne, Germany.

Antimicrob Resist Infect Control 2019 30;8:208. Epub 2019 Dec 30.

1Institute of Hygiene, Cologne Merheim Medical Centre, University Hospital of Witten/Herdecke, Ostmerheimer Strasse 200, 51109 Cologne, Germany.

Background: is a common pathogen causing hospital-acquired infections. Carbapenem resistance in is either mediated via a combination of efflux pumps, AmpC overexpression, and porin loss, or through an acquired carbapenemase. Carbapenemase-producing (CPPA) strains are known to cause outbreaks and harbour a reservoir of mobile antibiotic resistance genes, however, few molecular surveillance data is available. The aim of this study was to analyse the prevalence and epidemiology of CPPA in three German medical centres from 2015 to 2017.

Methods: Identification and susceptibility testing were performed with VITEK 2 system. non-susceptible to piperacillin, ceftazidime, cefepime, imipenem, meropenem and ciprofloxacin (4MRGN according to the German classification guideline) isolated from 2015 to 2017 were analysed. A two-step algorithm to detect carbapenemases was performed: phenotypic tests (EDTA- and cloxacillin-combined disk tests) followed by PCR, Sanger sequencing, and eventually whole genome sequencing. CPPA isolates were further genotyped by RAPD and PFGE. In-hospital transmission was investigated using conventional epidemiology.

Results: Sixty two isolates were available for further analysis, of which 21 were CPPA as follows: ( = 2), ( = 17), / (n = 1) and the newly described (n = 1). CPPA were mostly hospital-acquired (71.4%) and isolated on intensive care units (66.7%). All (except one) were from the tertiary care centre. PFGE typing revealed one large cluster of VIM-2-producing CPPA containing 13 isolates. However, using conventional epidemiology, we were only able to confirm three patient-to-patient transmissions, and one room-to-patient transmission, on several intensive care units.

Conclusions: These data give insight into the epidemiology of CPPA in three centres in Germany over a period of 3 years. Carbapenemases are a relevant resistance mechanism in 4MRGN- illustrated by genetically related VIM-2-producing strains that seem to be endemic in this region. Our data suggest that infection control measures should especially focus on controlling transmission on the ICU and support the need for a local molecular surveillance system.
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http://dx.doi.org/10.1186/s13756-019-0665-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6937969PMC
July 2020

Cytosolic Gram-negative bacteria prevent apoptosis by inhibition of effector caspases through lipopolysaccharide.

Nat Microbiol 2020 02 23;5(2):354-367. Epub 2019 Dec 23.

Institute for Medical Microbiology, Immunology and Hygiene, Centre for Molecular Medicine Cologne and Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases, University of Cologne, Cologne, Germany.

The cytosolic appearance and propagation of bacteria cause overwhelming cellular stress responses that induce apoptosis under normal conditions. Therefore, successful bacterial colonization depends on the ability of intracellular pathogens to block apoptosis and to safeguard bacterial replicative niches. Here, we show that the cytosolic Gram-negative bacterium Shigella flexneri stalls apoptosis by inhibiting effector caspase activity. Our data identified lipopolysaccharide (LPS) as a bona fide effector caspase inhibitor that directly binds caspases by involving its O-antigen (O Ag) moiety. Bacterial strains that lacked the O Ag or failed to replicate within the cytosol were incapable of blocking apoptosis and exhibited reduced virulence in a murine model of bacterial infection. Our findings demonstrate how Shigella inhibits pro-apoptotic caspase activity, effectively delays coordinated host-cell demise and supports its intracellular propagation. Next to the recently discovered pro-inflammatory role of cytosolic LPS, our data reveal a distinct mode of LPS action that, through the disruption of the early coordinated non-lytic cell death response, ultimately supports the inflammatory breakdown of infected cells at later time points.
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http://dx.doi.org/10.1038/s41564-019-0620-5DOI Listing
February 2020

Diversity of amino acid substitutions in PmrCAB associated with colistin resistance in clinical isolates of Acinetobacter baumannii.

Int J Antimicrob Agents 2020 Mar 16;55(3):105862. Epub 2019 Dec 16.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstraße 19-21, 50935 Cologne, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany. Electronic address:

This study aimed to investigate the mechanisms of colistin resistance in 64 Acinetobacter baumannii isolates obtained from patients with ventilator-associated pneumonia hospitalised in Greece, Italy and Spain. In total, 31 A. baumannii isolates were colistin-resistant. Several novel amino acid substitutions in PmrCAB were found in 27 colistin-resistant A. baumannii. Most substitutions were detected in PmrB, indicating the importance of the histidine kinase for colistin resistance. In two colistin-resistant isolates, 93 amino acid changes were observed in PmrCAB compared with A. baumannii ACICU, and homologous recombination across different clonal lineages was suggested. Analysis of gene expression revealed increased pmrC expression in isolates harbouring pmrCAB mutations. Complementation of A. baumannii ATCC 19606 and ATCC 17978 with a pmrAB variant revealed increased pmrC expression but unchanged colistin MICs, indicating additional unknown factors associated with colistin resistance. Moreover, a combination of PmrB and PmrC alterations was associated with very high colistin MICs, suggesting accumulation of mutations as the mechanism for high-level resistance. The pmrC homologue eptA was detected in 29 colistin-susceptible and 26 colistin-resistant isolates. ISAba1 was found upstream of eptA in eight colistin-susceptible and one colistin-resistant isolate and eptA was disrupted by ISAba125 in two colistin-resistant isolates. Whilst in most isolates an association of eptA with colistin resistance was excluded, in one isolate an amino acid substitution in EptA (R127L) combined with a point mutation in ISAba1 upstream of eptA contributed to elevated colistin MICs. This study helps to gain an insight into the diversity and complexity of colistin resistance in A. baumannii.
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http://dx.doi.org/10.1016/j.ijantimicag.2019.105862DOI Listing
March 2020

and Virulence Potential of the Emergent Species of the (Ab) Group.

Front Microbiol 2019 24;10:2429. Epub 2019 Oct 24.

ISGlobal, Hospital Clínic - University of Barcelona, Barcelona, Spain.

The increased use of molecular identification methods and mass spectrometry has revealed that spp. of the (Ab) group other than are increasingly being recovered from human samples and may pose a health challenge if neglected. In this study 76 isolates of 5 species within the Ab group ( = 16, = 12, = 16, = 20, and = 12), were compared in terms of antimicrobial susceptibility, carriage of intrinsic resistance genes, biofilm formation, and the ability to kill in an infection assay. In agreement with previous studies, antimicrobial resistance was common among while all other species were generally more susceptible. Carriage of genes encoding different efflux pumps was frequent in all species and the presence of intrinsic class D β-lactamases was reported in , (heterotypic synonym of ) and but not in and . and presented weaker pathogenicity in our and models than , and, especially, . Isolates from the former species showed decreased biofilm formation and required a longer time to kill nematodes. These results suggest relevant differences in terms of antibiotic susceptibility patterns among the members of the Ab group as well as highlight a higher pathogenicity potential for the emerging species of the group in this particular model. Nevertheless, the impact of such potential in the human host still remains to be determined.
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http://dx.doi.org/10.3389/fmicb.2019.02429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6821683PMC
October 2019

In vitro activity of the novel fluorocycline TP-6076 against carbapenem-resistant Acinetobacter baumannii.

Int J Antimicrob Agents 2020 Jan 16;55(1):105829. Epub 2019 Dec 16.

Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany.

The activity of the novel, fully synthetic fluorocycline antibiotic TP-6076 against carbapenem-resistant Acinetobacter baumannii (CRAB) isolates with defined carbapenem resistance mechanisms was compared against reference antimicrobials with known activity against Acinetobacter spp. The susceptibility of 323 non-duplicate CRAB isolates to TP-6076, amikacin, ampicillin/sulbactam (SAM), cefepime, colistin, doxycycline, eravacycline, imipenem, levofloxacin, meropenem, minocycline, rifampicin, sulbactam, tigecycline, tobramycin and trimethoprim/sulfamethoxazole (SXT) was determined by the broth microdilution method. TP-6076 showed greater activity than comparator antimicrobials of the tetracycline class, SAM, levofloxacin, amikacin, tobramycin, SXT and colistin. MIC and MIC values for TP-6076 were 0.06 mg/L and 0.25 mg/L, respectively. In comparison, doxycycline, eravacycline, minocycline and tigecycline MIC values were 32/≥64, 0.5/1, 4/8 and 1/2 mg/L, respectively. Compared with other compounds, TP-6076 was the most active antimicrobial against CRAB, including isolates that were resistant to other anti-Acinetobacter reference drugs including SAM, colistin, the aminoglycosides amikacin and tobramycin, and levofloxacin. TP-6076 is a promising new agent that may be a useful addition to the limited armamentarium of drugs targeting this problematic pathogen.
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http://dx.doi.org/10.1016/j.ijantimicag.2019.10.010DOI Listing
January 2020

Genetic Features of Antarctic Strain A154 Harboring Multiple Antibiotic-Resistance Genes.

Front Cell Infect Microbiol 2019 13;9:328. Epub 2019 Sep 13.

Laboratorio de Investigación en Agentes Antibacterianos (LIAA), Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.

While antibiotic-resistant bacteria have been detected in extreme environments, including Antarctica, to date there are no reports of species isolated from this region. Here, we characterized by whole-genome sequencing (WGS) the genetic content of a single antibiotic-resistant spp. isolate (A154) collected in Antarctica. The isolate was recovered in 2013 from soil samples at Fildes Peninsula, Antarctica, and was identified by detection of the intrinsic OXA-23 gene, and confirmed by Tetra Correlation Search (TCS) and WGS. The antibiotic susceptibility profile was determined by disc diffusion, E-test, and broth microdilution methods. From WGS data, the acquired resistome and insertion sequence (IS) content were identified by analyses. Plasmids were studied by the alkaline lysis method followed by pulsed-field gel electrophoresis and conventional PCR. The A154 isolate was identified as by WGS analysis and displayed >99.9 of similarity by TCS in relation with the databases. Moreover, it was resistant to ampicillin, ceftriaxone, ceftazidime, cefepime, cefotaxime, streptomycin, and kanamycin. Likewise, in addition to the intrinsic gene, A154 harbored the plasmid-encoded antibiotic-resistance genes , ', and , as well as a large diversity of ISs. This is the first report of antibiotic-resistant in Antarctica. Our findings show the presence of several resistance genes which could be either intrinsic or acquired in the region.
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http://dx.doi.org/10.3389/fcimb.2019.00328DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6755334PMC
June 2020

Restoring the activity of the antibiotic aztreonam using the polyphenol epigallocatechin gallate (EGCG) against multidrug-resistant clinical isolates of .

J Med Microbiol 2019 Oct;68(10):1552-1559

Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK.

. is an important Gram-negative pathogen that is intrinsically multidrug-resistant (MDR) and frequently associated with healthcare-associated outbreaks. With increasing resistance to antibiotics and with very few novel drugs under development, clinicians often use combinations to treat critically ill patients.. The aim of this study was to evaluate the ability of epigallocatechin (EGCG) to restore the activity of aztreonam against clinical MDR strains of .. Checkerboard and time-kill kinetic assays were performed to assess synergy and the model of infection was used to test the efficacy of the combination . Accumulation assays were performed to gain insight into the mechanism of action.. The results demonstrate that synergy between aztreonam and EGCG exists [fractional inhibitory concentration indices (FICIs) 0.02-0.5], with the combination affording significantly (=<0.05) enhanced bacterial killing, with a >3 log reduction in colony-forming units ml at 24 h. EGCG was able to restore susceptibility to aztreonam to a level equal to or below the breakpoint set by the European Committee for Antimicrobial Susceptibility Testing. In , the combination was superior to monotherapy, with increased larval survival observed (94 % vs ≤63 %). We also demonstrated the relatively low toxicity of EGCG to human keratinocytes and larvae. Accumulation assay data suggest that the mechanism of synergy may be due to EGCG increasing the uptake of aztreonam.. EGCG was able to restore the activity of aztreonam against MDR . The data presented support further evaluation of the aztreonam-EGCG combination and highlight its potential for use in clinical medicine.
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http://dx.doi.org/10.1099/jmm.0.001060DOI Listing
October 2019