Publications by authors named "Julia Walochnik"

127 Publications

Human dirofilariosis in Austria: the past, the present, the future.

Parasit Vectors 2021 Apr 29;14(1):227. Epub 2021 Apr 29.

Department of Dermatology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.

Background: Dirofilariosis is a vector-borne parasitosis caused by filarial nematodes of the genus Dirofilaria. In humans, who represent accidental hosts, dirofilariosis is mostly caused by Dirofilaria repens and Dirofilaria immitis. In Austria, the first reported case occurred in 1978. Since then, several (case) reports have been published.

Methods: A systematic and retrospective review of collected published cases and new, unpublished confirmed cases of human dirofilariosis occurring in Austria was performed. A nematode was extracted from the eyelid of a previously unreported case and subsequently characterized histologically and using molecular biology techniques.

Results: Data on a total of 39 cases of human dirofilariosis in Austria occurring between 1978 and 2020 are summarized. Over the past four decades the incidence has markedly increased, in particular after 1998. Of the 39 patients, men and women were equally affected, and the mean age was 47.1 years. The area most frequently affected was the head (38.5% of cases). Confined ocular involvement was observed in 23.1% of cases, and nematodes were isolated from the neck/trunk, extremities and the genito-inguinal area in 25.6, 15.4 and 15.4% of patients, respectively. Microfilariae were detected in two cases. Of the 39 patients, only 73.9% tested positive for anti-filarial antibodies and 56.3% for eosinophilia, despite successful isolation of a nematode; consequently, these measures did not represent reliable markers for dirofilariosis. Most patients had a travel history to countries endemic for Dirofilaria species. One patient who had not traveled abroad represented the only autochthonous case recorded to date. Dirofilaria repens was the predominant species, identified in 89.7% of cases. In the newly reported case of subcutaneous dirofilariosis, a live non-gravid Dirofilaria repens adult female of 12 cm length was isolated from the eyelid of the patient, and a video of the extraction is provided.

Conclusions: The incidence of human dirofilariosis cases has increased strikingly over the last four decades in Austria. More cases can be expected in the foreseeable future due to changes in human behavior and (travel) activities as well as climate changes and the associated alterations in the availability of the natural reservoir, the vectors and the intrinsic characteristics of the parasite.
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http://dx.doi.org/10.1186/s13071-021-04696-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8082911PMC
April 2021

Nosocomial Infections: Do Not Forget the Parasites!

Pathogens 2021 Feb 19;10(2). Epub 2021 Feb 19.

Institute for Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, 1090 Vienna, Austria.

Nosocomial infections (NIs) pose an increasing threat to public health. The majority of NIs are bacterial, fungal, and viral infections; however, parasites also play a considerable role in NIs, particularly in our increasingly complex healthcare environment with a growing proportion of immunocompromised patients. Moreover, parasitic infections acquired via blood transfusion or organ transplantation are more likely to have severe or fatal disease outcomes compared with the normal route of infection. Many of these infections are preventable and most are treatable, but as the awareness for parasitic NIs is low, diagnosis and treatment are often delayed, resulting not only in higher health care costs but, importantly, also in prolonged courses of disease for the patients. For this article, we searched online databases and printed literature to give an overview of the causative agents of parasitic NIs, including the possible routes of infection and the diseases caused. Our review covers a broad spectrum of cases, ranging from widely known parasitic NIs, like blood transfusion malaria or water-borne cryptosporidiosis, to less well-known NIs, such as the transmission of by solid organ transplantation or nosocomial myiasis. In addition, emerging NIs, such as babesiosis by blood transfusion or person-to-person transmitted scabies, are described.
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http://dx.doi.org/10.3390/pathogens10020238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923136PMC
February 2021

An unusual thioredoxin system in the facultative parasite Acanthamoeba castellanii.

Cell Mol Life Sci 2021 Apr 18;78(7):3673-3689. Epub 2021 Feb 18.

Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, 1090, Vienna, Austria.

The free-living amoeba Acanthamoeba castellanii occurs worldwide in soil and water and feeds on bacteria and other microorganisms. It is, however, also a facultative parasite and can cause serious infections in humans. The annotated genome of A. castellanii (strain Neff) suggests the presence of two different thioredoxin reductases (TrxR), of which one is of the small bacterial type and the other of the large vertebrate type. This combination is highly unusual. Similar to vertebrate TrxRases, the gene coding for the large TrxR in A. castellanii contains a UGA stop codon at the C-terminal active site, suggesting the presence of selenocysteine. We characterized the thioredoxin system in A. castellanii in conjunction with glutathione reductase (GR), to obtain a more complete understanding of the redox system in A. castellanii and the roles of its components in the response to oxidative stress. Both TrxRases localize to the cytoplasm, whereas GR localizes to the cytoplasm and the large organelle fraction. We could only identify one thioredoxin (Trx-1) to be indeed reduced by one of the TrxRases, i.e., by the small TrxR. This thioredoxin, in turn, could reduce one of the two peroxiredoxins tested and also methionine sulfoxide reductase A (MsrA). Upon exposure to hydrogen peroxide and diamide, only the small TrxR was upregulated in expression at the mRNA and protein levels, but not the large TrxR. Our results show that the small TrxR is involved in the A. castellanii's response to oxidative stress. The role of the large TrxR, however, remains elusive.
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http://dx.doi.org/10.1007/s00018-021-03786-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038987PMC
April 2021

Phlebotomus (Adlerius) simici NITZULESCU, 1931: first record in Austria and phylogenetic relationship with other Adlerius species.

Parasit Vectors 2021 Jan 6;14(1):20. Epub 2021 Jan 6.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

Background: Phlebotomine sand flies are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). Information on sand flies in Central Europe is scarce and, to date, in Austria, only Phlebotomus mascittii has been recorded. In 2018 and 2019, entomological surveys were conducted in Austria with the aim to further clarify sand fly distribution and species composition.

Results: In 2019, a Ph. simici specimen was trapped in Austria for the first time. Analyses of two commonly used marker genes, cytochrome c oxidase I (coxI) and cytochrome b (cytb), revealed high sequence identity with Ph. simici specimens from North Macedonia and Greece. Phylogenetic analyses showed high intraspecific distances within Ph. simici, thereby dividing this species into three lineages: one each from Europe, Turkey and Israel. Low interspecific distances between Ph. simici, Ph. brevis and an as yet unidentified Adlerius sp. from Turkey and Armenia highlight how challenging molecular identification within the Adlerius complex can be, even when standard marker genes are applied.

Conclusion: To our knowledge, this study reports the first finding of Ph. simici in Austria, representing the northernmost recording of this species to date. Moreover, it reveals valuable insights into the phylogenetic relationships among species within the subgenus Adlerius. Phlebotomus simici is a suspected vector of L. infantum and therefore of medical and veterinary importance. Potential sand fly expansion in Central Europe due to climatic change and the increasing import of Leishmania-infected dogs from endemic areas support the need for further studies on sand fly distribution in Austria and Central Europe in general.
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http://dx.doi.org/10.1186/s13071-020-04482-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7788815PMC
January 2021

Free-living amoebae and other neglected protistan pathogens: Health emergency signals?

Eur J Protistol 2021 Feb 28;77:125760. Epub 2020 Nov 28.

Division of Infectious Diseases, Department of Medicine, University of Alberta, Alberta, Canada; Institute of Parasitology, Biology Centre, Czech Academy of Sciences České Budějovice, Czech Republic. Electronic address:

Protistan parasites have an undisputed global health impact. However, outside of a few key exceptions, e.g. the agent of malaria, most of these infectious agents are neglected as important health threats. The Symposium entitled "Free-living amoebae and neglected pathogenic protozoa: health emergency signals?" held at the European Congress of Protistology in Rome, July 2019, brought together researchers addressing scientific and clinical questions about some of these fascinating organisms. Topics presented included the molecular basis of pathogenicity in Acanthamoeba; genomics of Naegleria fowleri; and epidemiology of poorly diagnosed enteric protistan species, including Giardia, Cryptosporidium, Blastocystis, Dientamoeba. The Symposium aim was to excite the audience about the opportunities and challenges of research in these underexplored organisms and to underline the public health implications of currently under-appreciated protistan infections. The major take home message is that any knowledge that we gain about these organisms will allow us to better address them, in terms of monitoring and treatment, as sources of future health emergencies.
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http://dx.doi.org/10.1016/j.ejop.2020.125760DOI Listing
February 2021

Integrative Approach to Grassi, 1908: First Record in Vienna with New Morphological and Molecular Insights.

Pathogens 2020 Dec 9;9(12). Epub 2020 Dec 9.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria.

Sand flies (Diptera: Psychodidae: Phlebotominae) are blood-feeding insects that transmit the protozoan parasites spp. and various arthropod-borne (arbo) viruses. While in Mediterranean parts of Europe the sand fly fauna is diverse, in Central European countries including Austria mainly is found, an assumed but unproven vector of . To update the currently understudied sand fly distribution in Austria, a sand fly survey was performed and other entomological catches were screened for sand flies. Seven new trapping locations of are reported including the first record in Vienna, representing also one of the first findings of this species in a city. Morphological identification, supported by fluorescence microscopy, was confirmed by two molecular approaches, including sequencing and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) protein profiling. Sand fly occurrence and activity were evaluated based on surveyed locations, habitat requirements and climatic parameters. Moreover, a first comparison of European populations was made by two marker genes, cytochrome c oxidase subunit 1 (), and cytochrome b (), as well as MALDI-TOF mass spectra. Our study provides new important records of in Austria and valuable data for prospective entomological surveys. MALDI-TOF MS protein profiling was shown to be a reliable tool for differentiation between sand fly species. Rising temperatures and globalization demand for regular entomological surveys to monitor changes in species distribution and composition. This is also important with respect to the possible vector competence of .
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http://dx.doi.org/10.3390/pathogens9121032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7764109PMC
December 2020

Anti-Acanthamoeba disinfection: hands, surfaces and wounds.

Int J Antimicrob Agents 2020 Oct 31;56(4):106122. Epub 2020 Jul 31.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, 1090 Vienna, Austria. Electronic address:

Acanthamoebae are facultative parasites causing rare but serious infections such as keratitis and encephalitis and are also known as vectors for several bacterial pathogens, including legionellae and pseudomonads. Acanthamoeba cysts are particularly resilient and enable the amoebae to withstand desiccation and to resist disinfection and therapy. While the search for new therapeutic options has been intensified in the past years, hand and surface disinfectants as well as topical antiseptics for preventing infections have not been studied in detail to date. The aim of this study was to screen well-known and commonly used antimicrobial products in various formulations and different concentrations for their efficacy against Acanthamoeba trophozoites and cysts, including aliphatic alcohols, quaternary ammonium compounds (QACs), peracetic acid (PAA), potassium peroxymonosulfate sulfate (PPMS) and octenidine dihydrochloride (OCT). Of all products tested, OCT and QACs showed the highest efficacy, totally eradicating both trophozoites and cysts within 1 min. The determined 50% effective concentration (EC) for cysts was 0.196 mg/mL for OCT and 0.119 mg/mL for QACs after 1 min of exposure. PAA and PPMS showed reliable cysticidal efficacies only with prolonged incubation times of 30 min and 60 min, respectively. Aliphatic alcohols generally had limited efficacy, and only against trophozoites. In conclusion, OCT and QACs are potent actives against Acanthamoeba trophozoites and cysts at concentrations used in commercially available products, within contact times suitable for surface and hand disinfection as well as topical antisepsis.
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http://dx.doi.org/10.1016/j.ijantimicag.2020.106122DOI Listing
October 2020

Untargeted metagenomics shows a reliable performance for synchronous detection of parasites.

Parasitol Res 2020 Aug 26;119(8):2623-2629. Epub 2020 Jun 26.

Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald-Insel Riems, Germany.

Shotgun metagenomics with high-throughput sequencing (HTS) techniques is increasingly used for pathogen identification and characterization. While many studies apply targeted amplicon sequencing, here we used untargeted metagenomics to simultaneously identify protists and helminths in pre-diagnosed faecal and tissue samples. The approach starts from RNA and operates without an amplification step, therefore allowing the detection of all eukaryotes, including pathogens, since it circumvents the bias typically observed in amplicon-based HTS approaches. The generated metagenomics datasets were analysed using the RIEMS tool for initial taxonomic read assignment. Mapping analyses against ribosomal reference sequences were subsequently applied to extract 18S rRNA sequences abundantly present in the sequence datasets. The original diagnosis, which was based on microscopy and/or PCR, could be confirmed in nearly all cases using ribosomal RNA metagenomics. In addition to the pre-diagnosed taxa, we detected other intestinal eukaryotic parasites of uncertain pathogenicity (of the genera Dientamoeba, Entamoeba, Endolimax, Hymenolepis) that are often excluded from routine diagnostic protocols. The study clearly demonstrates the applicability of untargeted RNA metagenomics for the parallel detection of parasites.
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http://dx.doi.org/10.1007/s00436-020-06754-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7366571PMC
August 2020

Validation of reference genes for the normalization of RT-qPCR gene expression in Acanthamoeba spp.

Sci Rep 2020 06 25;10(1):10362. Epub 2020 Jun 25.

Institute of Specific Prophylaxis und Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

Acanthamoebae are potentially pathogenic organisms, with a highly unique, yet still insufficiently investigated metabolism. Many open questions can be addressed by gene expression studies, however, for Acanthamoeba reliable standards have not yet been established. In this study, suitable reference genes (RGs) for RT-qPCR in Acanthamoeba were comprehensively evaluated, comparing different Acanthamoeba strains and employing four different algorithms (NormFinder, GeNorm, BestKeeper and RefFinder). Expression stability was assessed under various conditions and the potentials of the most promising RGs for accurate normalization of target genes were evaluated. Expression stability of RGs varied depending on conditions and employed algorithms, however, the genes for the 18S rRNA and the hypoxanthine phosphoribosyl transferase seem to be widely suitable RGs. Normalization with a combination of two carefully chosen RGs resulted in reliable expression data for target genes, while normalization with unsuitable RGs led to significant misinterpretation of expression profiles. Thus, a careful evaluation of RGs prior to expression studies is essential.
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http://dx.doi.org/10.1038/s41598-020-67035-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7316857PMC
June 2020

A novel 5-Plex qPCR-HRM assay detecting human diarrheal parasites.

Gut Pathog 2020 29;12:27. Epub 2020 May 29.

Institute for Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, 1090 Vienna, Austria.

Background: Intestinal parasitic diseases occur worldwide, and their diagnosis poses considerable challenges. spp., (and, arguably, and spp.) are among the most important and common parasitic protozoans causing diarrhea. Several multiplex real-time PCR assays have been developed for the synchronous detection of these parasites. However, most assays include the use of hydrolysis probes, increasing the cost of stool examination. In this study, we designed and evaluated a real-time PCR protocol, based on high-resolution melting (HRM) curve analysis, to simultaneously detect and differentiate five gastrointestinal parasites.

Results: Using a blinded panel of 143 clinical samples with laboratory diagnostic data to evaluate the method, we obtained a 95.8% concordance with conventional methods. Moreover, 4.2% of the samples were positive for and 2.8% additional infections were found with our multiplex assay. Our method is sensitive and specific for the selected parasites with the additional possibility of being run in single-plex as a backup control for mixed infections.

Conclusions: The assay is a convenient and cost-effective method that could contribute to a quicker and accurate diagnosis as well as to more targeted therapies of parasite-derived diarrhea. Finally, this new multiplex PCR assay could also be instrumental in epidemiology studies on these parasites.
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http://dx.doi.org/10.1186/s13099-020-00365-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7257150PMC
May 2020

Diversity of digenean trematode larvae in snails from Lake Victoria, Kenya: First reports and bioindicative aspects.

Acta Trop 2020 Jun 6;206:105437. Epub 2020 Mar 6.

University of Vienna, Institute of Inorganic Chemistry, Althanstrasse 14, 1090, Vienna, Austria; University of Johannesburg, Department of Zoology, P.O. Box 524, Auckland Park, 2006, South Africa. Electronic address:

This study investigated the occurrence of digenean trematode larvae in snails from the Kenyan part of Lake Victoria. The survey included caenogastropod snails that have received less focus in parasitological studies in Africa: their trematodes are largely unknown. Out of 1145 snail specimens, 149 (13.0%) were infected with Digenea. The highest prevalence (P) was recorded in Melanoides tuberculata (64.5%), followed by Pila ovata (15.4%), Radix natalensis (9.5%), Bulinus ugandae (9.1%), Bellamya unicolor (8.9%), Biomphalaria pfeifferi (7.3%) and Biomphalaria sudanica (4.4%). Morphological and molecular analyses revealed 17 digenean species. Contrary to reports of low diversity of Digenea in caenogastropods, P. ovata harboured 8 species - at least twice as many as in each of the pulmonates. The following taxa are reported for the first time in the Lake Victoria region: Haplorchis pumilio, Thapariella prudhoei, Nudacotyle sp., Renicola sp. and Bolbophorus sp. An unknown cercaria belonging to the genus Haematoloechus is reported from P. ovata: a xiphidiocercaria possessing a long sword-shaped stylet (47-71 µm) which does not match any available literature records. From this study, H. pumilio from M. tuberculata (P = 69.4%), Fasciola gigantica from R. natalensis (P = 1.9%) and Bolbophorus sp. from Bu. ugandae (P = 4.6%) are species of veterinary or medical importance. Snails from the study site with little direct anthropogenic influence had the highest prevalence and diversity of digenean larvae, indicating that environmental conditions influence trematode occurrence.
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http://dx.doi.org/10.1016/j.actatropica.2020.105437DOI Listing
June 2020

Genetic diversity of Fasciola hepatica in Austria.

Parasitol Res 2020 May 3;119(5):1697-1701. Epub 2020 Mar 3.

Institute for Specific Prophylaxis and Tropical Medicine, Medical University Vienna, 1090, Vienna, Austria.

The worldwide occurring common liver fluke Fasciola hepatica can infect humans and animals and leads to considerable illness and economic loss annually. The aim of this study was to determine the genetic diversity of F. hepatica in Austria. In total, 31 adult flukes isolated from cattle from various regions in Austria were investigated for their cytochrome oxidase subunit 1 (cox1) and nicotinamide dehydrogenase subunit 1 (nad1) gene sequences. It was shown that Austrian isolates of F. hepatica reveal extensive genetic diversity. To the best of our knowledge, these are the first data on the diversity of F. hepatica in Austria.
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http://dx.doi.org/10.1007/s00436-020-06633-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7184038PMC
May 2020

Solving an old enigma: Morellospora saccamoebae gen. nov., sp. nov. (Rozellomycota), a Sphaerita-like parasite of free-living amoebae.

Parasitol Res 2020 Mar 11;119(3):925-934. Epub 2020 Feb 11.

Department of Pathology, Electron Microscopy Facility, Bundeswehr Central Hospital Koblenz, Andernacher Strasse 100, 56070, Koblenz, Germany.

The Rozellomycota form a lineage basal or sister to the Fungi, ancestor of Microsporidia. Their biodiversity is very rich but remains poorly characterized. The few known species are all parasites, whether of water molds and algae (Rozella), crustaceans (Mitosporidium), or as endonuclear parasites of amoebae (Nucleophaga, Paramicrosporidium). Since the nineteenth century, intracytoplasmic parasites of various protozoa have been described as species of the same genus Sphaerita. However, it was later thought possible to separate these parasites into at least two distinct groups, those forming flagellated zoospores, prevalent in Euglena and other flagellates, and those forming immobile spores, found mainly in free-living and endozoic amoebae. Herein, we report the recovery of a strain of the free-living amoeba species Saccamoeba lacustris, naturally infected by an intracytoplasmic parasite, which under light microscope has a morphology consistent with that of Sphaerita. Biomolecular analyses were thus performed. Our results show that the intracytoplasmic parasite of Saccamoeba belongs to the same subgroup of Mitosporidium and that it forms a new genus within Rozellomycota, Morellospora, that corresponds to the former spore-forming Sphaerita-like parasites of amoebae.
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http://dx.doi.org/10.1007/s00436-020-06623-5DOI Listing
March 2020

Leishmania spp. seropositivity in Austrian soldiers returning from the Kosovo.

Wien Klin Wochenschr 2020 Jan 7;132(1-2):47-49. Epub 2020 Jan 7.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University Vienna, Kinderspitalgasse 15, 1090, Vienna, Austria.

Leishmaniasis is a severe vector-borne disease with two main clinical forms, visceral leishmaniasis and cutaneous leishmaniasis. Both forms of leishmaniasis are also endemic in Mediterranean countries including the Balkan region from where mainly visceral leishmaniasis is reported. Austrian soldiers returning from Kosovo were screened for anti-Leishmania antibodies to assess the risk of infection during operations. Anti-Leishmania antibodies were detected in more than 20% of the soldiers investigated, which indicates a considerable risk of infection during missions in this area and thus suggests the application of protective measures.
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http://dx.doi.org/10.1007/s00508-019-01598-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978428PMC
January 2020

Activity of methylgerambullin from Glycosmis species (Rutaceae) against Entamoeba histolytica and Giardia duodenalis in vitro.

Int J Parasitol Drugs Drug Resist 2019 08 10;10:109-117. Epub 2019 Aug 10.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, A-1090, Vienna, Austria. Electronic address:

Entamoeba histolytica and Giardia duodenalis are widespread intestinal protozoan parasites which both spread via cysts that have to be ingested to infect a new host. Their environment, the small intestine for G. duodenalis and the colon for E. histolytica, contains only very limited amounts of oxygen, so both parasites generate energy by fermentation and substrate level phosphorylation rather than by oxidative phosphorylation. They both contain reducing agents able to reduce and activate nitroimidazole drugs such as metronidazole which is the gold standard drug to treat Entamoeba or Giardia infections. Although metronidazole works well in the majority of cases, it has a number of drawbacks. In animal models, the drug has carcinogenic activity, and concerns about a possible teratogenic activity remain. In addition, the treatment of G. duodenalis infections is hampered by emerging metronidazole resistance. Plant-derived drugs play a dominant role in human medicine, therefore we tested the activity of 14 isolated plant compounds belonging to seven different classes in vitro against both parasites. The tests were performed in a new setting in microtiter plates under anaerobic conditions. The compound with the highest activity was methylgerambullin, a sulphur-containing amide found in Glycosmis species of the family Rutaceae with an EC of 14.5 μM (6.08 μg/ml) after 24 h treatment for E. histolytica and 14.6 μM (6.14 μg/ml) for G. duodenalis. The compound was successfully synthesised in the laboratory which opens the door for the generation of new derivatives with higher activity.
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http://dx.doi.org/10.1016/j.ijpddr.2019.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6722286PMC
August 2019

Phlebovirus seroprevalence in Austrian Army personnel returning from missions abroad.

Parasit Vectors 2019 Aug 24;12(1):416. Epub 2019 Aug 24.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

Background: Phleboviruses are mainly transmitted by sand flies and infections can result in various symptoms, including meningitis and meningoencephalitis. In endemic regions, seroprevalences in humans and animals are high. Military personnel on missions in endemic areas are at increased risk of infection, however, for soldiers from central European countries, data are scarce. The aims of this study were to determine the exposure to phleboviruses of Austrian soldiers returning from missions abroad and to assess potential risk factors. A retrospective serological study was performed with sera of 753 healthy Austrian soldiers returning from missions in Bosnia and Herzegovina (BIH, n = 61), Kosovo (n = 261), Syria (n = 101) and Lebanon (n = 63) and of soldiers prior to their missions (n = 267).

Results: Altogether, 119 sera (15.8%, 119/753) were positive for anti-Phlebovirus IgG antibodies, with highest seroprevalences found in soldiers returning from Kosovo (20.69%, 54/261), followed by Syria (17.82%, 18/101), Lebanon (14.29%, 9/63) and BIH (11.48%, 7/61). Of the soldiers tested prior to their missions 11.61% (31/267) were positive. Of the 119 seropositive individuals, 30 (25.2%, 30/119) also had anti-Phlebovirus IgM antibodies. Phlebovirus seropositivity significantly correlated with symptoms of febrile illness during the respective mission (OR: 1.9, 95% CI: 1.1-3.4, P = 0.03) and with Leishmania seropositivity (OR: 2.7, 95% CI: 1.2-5.8, P = 0.009). Also, the outdoor activity "running" during the mission showed a strong trend towards an association with Phlebovirus seropositivity (OR: 1.9, 95% CI: 0.9-4.4, P = 0.08), and seropositivity generally increased with the duration of a mission (OR: 2.5, 95% CI: 0.9-7.5, P = 0.07).

Conclusions: This study indicates that soldiers are exposed to sand flies and at significant risk for Phlebovirus infection during missions in the Mediterranean area and the Middle East. Adequate prevention measures should be applied particularly during vespertine outdoor activities.
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http://dx.doi.org/10.1186/s13071-019-3674-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6708154PMC
August 2019

The cooling tower water microbiota: Seasonal dynamics and co-occurrence of bacterial and protist phylotypes.

Water Res 2019 Aug 22;159:464-479. Epub 2019 Apr 22.

Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria. Electronic address:

Cooling towers for heating, ventilation and air conditioning are ubiquitous in the built environment. Often located on rooftops, their semi-open water basins provide a suitable environment for microbial growth. They are recognized as a potential source of bacterial pathogens and have been associated with disease outbreaks such as Legionnaires' disease. While measures to minimize public health risks are in place, the general microbial and protist community structure and dynamics in these systems remain largely elusive. In this study, we analysed the microbiome of the bulk water from the basins of three cooling towers by 16S and 18S rRNA gene amplicon sequencing over the course of one year. Bacterial diversity in all three towers was broadly comparable to other freshwater systems, yet less diverse than natural environments; the most abundant taxa are also frequently found in freshwater or drinking water. While each cooling tower had a pronounced site-specific microbial community, taxa shared among all locations mainly included groups generally associated with biofilm formation. We also detected several groups related to known opportunistic pathogens, such as Legionella, Mycobacterium, and Pseudomonas species, albeit at generally low abundance. Although cooling towers represent a rather stable environment, microbial community composition was highly dynamic and subject to seasonal change. Protists are important members of the cooling tower water microbiome and known reservoirs for bacterial pathogens. Co-occurrence analysis of bacteria and protist taxa successfully captured known interactions between amoeba-associated bacteria and their hosts, and predicted a large number of additional relationships involving ciliates and other protists. Together, this study provides an unbiased and comprehensive overview of microbial diversity of cooling tower water basins, establishing a framework for investigating and assessing public health risks associated with these man-made freshwater environments.
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http://dx.doi.org/10.1016/j.watres.2019.04.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6554697PMC
August 2019

Viability and infectivity of viable but nonculturable Legionella pneumophila strains induced at high temperatures.

Water Res 2019 Jul 9;158:268-279. Epub 2019 Apr 9.

Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria; Karl Landsteiner University of Health Sciences, Division Water Quality and Health, Dr. Karl Dorrekstraße 30, A-3400, Krems, Austria.

Thermal disinfection is commonly used to prevent the proliferation of culturable Legionella in engineered water systems (EWS). In response to such stress, culturable Legionella populations can switch into a viable but nonculturable (VBNC) state. The importance of such VBNC Legionella cells is currently hotly debated. Here, we investigated the stress response patterns and transitions of the bacteria to the VBNC state at 55 °C, 60 °C and 70 °C on two L. pneumophila strains for >80 days using a combination of cell-based viability indicators. Complete loss of culturability at 55 °C, 60 °C and 70 °C occurred after 3-8 h, 60 min and <2 min, respectively. In contrast, L. pneumophila strains required 9 days at 55 °C, 8 h at 60 °C and 20 min at 70 °C to achieve a 2 log reduction in cells with intact membranes and high esterase activity; a 4 log reduction was achieved only after 150, 8-15 and 1-4 days, respectively. In parallel, the presence of diagnostic outer-membrane epitopes (OMEs) and changes in the infectivity patterns of the two strains towards amoebae and THP-1 cells were assessed. OMEs were more persistent than viability indicators, showing their potential as targets for VBNC Legionella detection. L. pneumophila strains infected amoebae and THP-1 cells for at least 85 days at 55 °C and 60 °C and for up to 8 days at 70 °C. However, they did so with reduced efficiency, requiring prolonged co-incubation times with the hosts and higher Legionella cell numbers in comparison to culturable cells. Consequently, infection of amoebae by thermally induced VBNC L. pneumophila with lowered virulence can be expected in EWS. Although the gold standard method cannot detect VBNC Legionella, it provides important information about the most virulent bacterial subpopulations. Our results indicate that a prolonged thermal regime ≥60 °C at the central parts of warm water systems is not only effective against culturable L. pneumophila but in the long run even against VBNC cells.
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http://dx.doi.org/10.1016/j.watres.2019.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520252PMC
July 2019

Report of the 2019 meeting of the German Society for Protozoology.

Authors:
Julia Walochnik

Eur J Protistol 2019 06 10;69:151. Epub 2019 Apr 10.

Medical University of Vienna, Center for Pathophysiology, Infectiology and Immunology, Institute of Specific Prophylaxis and Tropical Medicine, Austria. Electronic address:

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http://dx.doi.org/10.1016/j.ejop.2019.04.001DOI Listing
June 2019

N-chlorotaurine Inactivates Acanthamoeba and Candida albicans in the Porcine Ex Vivo Corneal Infection Model.

Cornea 2019 Aug;38(8):1011-1016

Division of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria.

Purpose: N-chlorotaurine (NCT) is an anti-infective belonging to the class of chloramines and an investigative drug for the topical treatment of keratoconjunctivitis. The aim of the present study was to demonstrate its efficacy against Acanthamoeba and Candida in corneas infected ex vivo.

Methods: Corneal buttons from porcine eyes were contaminated with Acanthamoeba castellanii trophozoites or Candida albicans Centraalbureau voor Schimmelcultures 5982 and incubated for 7 and 3 days, respectively. Subsequently, they were treated with 1% NCT for 5 to 120 minutes. After further incubation for 2 days in the absence of NCT in tests with A. castellanii, the buttons were homogenized, and the amoebae grown for a further 5 days before they were counted in a light microscope. For C. albicans, quantitative cultures were performed from corneal homogenates.

Results: Incubation of 120 minutes in NCT completely inhibited the regrowth of A. castellanii and reduced the number of C. albicans colony-forming unit counts by 4 log10. In addition, at 60 minutes, significant reductions of both pathogens could be observed. Histology showed penetration of pathogens into the stroma of the corneal buttons.

Conclusions: NCT inactivates A. castellanii and C. albicans in corneal tissue.
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http://dx.doi.org/10.1097/ICO.0000000000001927DOI Listing
August 2019

Recovery of an Acanthamoeba strain with two group I introns in the nuclear 18S rRNA gene.

Eur J Protistol 2019 Apr 28;68:88-98. Epub 2019 Jan 28.

Institute of Tropical Medicine and Specific Prophylaxis, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Kinderspitalgasse 15, 1090 Vienna, Austria.

Nuclear group I introns are parasitic mobile genetic elements occurring in the ribosomal RNA genes of a large variety of microbial eukaryotes. In Acanthamoeba, group I introns were found occurring in the 18S rDNA at four distinct insertion sites. Introns are present as single elements in various strains belonging to four genotypes, T3 (A. griffini), T4 (A. castellanii complex), T5 (A. lenticulata) and T15 (A. jacobsi). While multiple introns can frequently be found in the rDNA of several algae, fungi and slime moulds, they are usually rare and present as single elements in amoebae. We reported herein the characterization of an A. lenticulata strain containing two introns in its 18S rDNA. They are located to already known sites and show basal relationships with respective homologous introns present in the other T5 strains. This is the first and unique reported case of multiple nuclear introns in Acanthamoeba.
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http://dx.doi.org/10.1016/j.ejop.2019.01.007DOI Listing
April 2019

Successful extraction and PCR amplification of Giardia DNA from formalin-fixed stool samples.

Exp Parasitol 2019 Mar 30;198:26-30. Epub 2019 Jan 30.

Institute of Specific Prophylaxis and Tropical Medicine, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria.

Extracting genomic DNA of pathogenic agents from formalin-fixed specimens is inherently difficult. Storage of samples in formalin results in nucleic acid cross-linking and DNA fragmentation. In this study, DNA was extracted from 45 Giardia-positive stool samples stored in formalin and subjected to PCR amplification targeting the triose phosphate isomerase (tpi), beta gardin (bg) and glutamate dehydrogenase (gdh) genes. Samples were rehydrated by using a descending alcohol series before DNA extraction using a commercial kit. This was followed by EDTA-mediated inhibition of DNase activity and prolonged treatment with proteinase K to digest contaminating proteins. DNA was amplified at rates of 64.4% (29/45) at the tpi, 40% (18/45) at the bg and 20% (9/45) at the gdh loci as seen on nested PCR. DNA quality was subsequently tested in a genotyping experiment which produced high-quality sequences at the tpi (41.2%; 12/29) bg (50%; 9/18), and gdh (22.2%; 2/9) loci and enabled differentiation of Giardia strains at the subtype level. The modified extraction protocol was effective at removing inhibitors and reversing cross-linking of DNA. However, PCR amplification was limited to short fragments of DNA which resulted in highest success rate on amplification of the shortest (334 bp) gene fragment tested.
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http://dx.doi.org/10.1016/j.exppara.2019.01.010DOI Listing
March 2019

Chemotherapeutic options for the treatment of human trichomoniasis.

Int J Antimicrob Agents 2019 Feb 27;53(2):116-127. Epub 2018 Oct 27.

Institute of Specific Prophylaxis and Tropical Medicine, Centre for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090 Vienna, Austria. Electronic address:

Trichomonas vaginalis is the causative agent of the most common non-viral sexually transmitted disease worldwide. The infection may be associated with severe complications, including infertility, preterm labour, cancer and an increased risk of human immunodeficiency virus (HIV) transmission. Treatment remains almost exclusively based on 5-nitroimidazoles, but resistance is on the rise. This article provides an overview of clinically evaluated systemic and topical treatment options for human trichomoniasis and summarises the current state of knowledge on various herbal, semisynthetic and synthetic compounds evaluated for their anti-Trichomonas efficacy in vitro.
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http://dx.doi.org/10.1016/j.ijantimicag.2018.10.016DOI Listing
February 2019

Filling gaps in the microsporidian tree: rDNA phylogeny of Chytridiopsis typographi (Microsporidia: Chytridiopsida).

Parasitol Res 2019 Jan 12;118(1):169-180. Epub 2018 Nov 12.

University of Natural Resources and Life Sciences, Gregor Mendel Str. 33, 1180, Vienna, Austria.

Microsporidia are intracellular eukaryotic parasites of animals, characterized by unusual morphological and genetic features. They can be divided in three main groups, the classical microsporidians presenting all the features of the phylum and two putative primitive groups, the chytridiopsids and metchnikovellids. Microsporidia originated from microsporidia-like organisms belonging to a lineage of chytrid-like endoparasites basal or sister to the Fungi. Genetic and genomic data are available for all members, except chytridiopsids. Herein, we filled this gap by obtaining the rDNA sequence (SSU-ITS-partial LSU) of Chytridiopsis typographi (Chytridiopsida), a parasite of bark beetles. Our rDNA molecular phylogenies indicate that Chytridiopsis branches earlier than metchnikovellids, commonly thought ancestral, forming the more basal lineage of the Microsporidia. Furthermore, our structural analyses showed that only classical microsporidians present 16S-like SSU rRNA and 5.8S/LSU rRNA gene fusion, whereas the standard eukaryote rRNA gene structure, although slightly reduced, is still preserved in the primitive microsporidians, including 18S-like SSU rRNA with conserved core helices, and ITS2-like separating 5.8S from LSU. Overall, our results are consistent with the scenario of an evolution from microsporidia-like rozellids to microsporidians, however suggesting for metchnikovellids a derived position, probably related to marine transition and adaptation to hyperparasitism. The genetic and genomic data of additional members of Chytridiopsida and Rozellomycota will be of great value, not only to resolve phylogenetic relationships but also to improve our understanding of the evolution of these fascinating organisms.
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http://dx.doi.org/10.1007/s00436-018-6130-1DOI Listing
January 2019

Identification of free-living amoebae isolated from tap water in Istanbul, Turkey.

Exp Parasitol 2018 Dec 15;195:34-37. Epub 2018 Oct 15.

Molecular Parasitology, Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, 1090, Vienna, Austria.

Free-living amoebae (FLA) are widely spread in the environment and also known to cause rare but often serious infections. The present work focuses on a local survey on FLA. It is essential to know the prevalence and distribution of these microorganisms in order to get infections caused by them under control. In this study, FLA isolated from domestic tap water samples from homes of contact lens wearers were identified by morphology and by 18S rRNA gene sequence analysis. Morphological analysis and partial sequencing of the 18S rDNA revealed the presence of Acanthamoeba genotype T4 and Vermamoeba vermiformis in the investigated tap water samples. Naegleria fowleri, Balamuthia mandrillaris, and Sappinia spp. were not detected during this study. It was shown that species of FLA known to cause eye infections in humans are widely distributed in tap water in Istanbul, Turkey. Contact lens wearers should be aware of the risk of contamination from tap water and strictly apply stringent contact lens hygiene. With this study, we established Acanthamoeba genotype T4 and Vermamoeba vermiformis as contaminants of tap water in Istanbul.
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http://dx.doi.org/10.1016/j.exppara.2018.10.002DOI Listing
December 2018

Leishmaniasis in Northern Syria during Civil War.

Emerg Infect Dis 2018 11;24(11):1973-1981

Since the onset of the ongoing civil war in Syria, the governmental surveillance system for leishmaniasis has lost access to provinces of northern Syria. The MENTOR Initiative, an international not-for-profit organization, was commissioned to implement an integrated leishmaniasis control program, providing an opportunity to reassess the epidemiology of leishmaniasis in northern Syria. Epidemiologic data and biologic samples for molecular species diagnostics were collected from collaborating local health centers. Incidence peaked in March 2015 at 7,743 estimated monthly cases. High levels of transmission were observed in traditional endemic regions but extended to previously hypoendemic regions, such as Al-Raqqa and Al-Hasakah. Incidence decreased to 3,209 in July 2015. Data indicate that the prewar trend of increasing incidence of cutaneous leishmaniasis accelerated during the beginning of armed conflict but declined after implementation of the comprehensive control program by the MENTOR Initiative. Molecular analysis revealed a spectrum of Leishmania species and sporadic cases of visceral leishmaniasis.
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http://dx.doi.org/10.3201/eid2411.172146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6199995PMC
November 2018

Lethal outcome of granulomatous acanthamoebic encephalitis in a man who was human immunodeficiency virus-positive: a case report.

J Med Case Rep 2018 Jul 12;12(1):201. Epub 2018 Jul 12.

Division of Clinical Toxicology & Poison Control Centre Munich, Department of Internal Medicine II, TUM School of Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Background: Acanthamoeba species can cause disseminating infections in immunocompromised individuals.

Case Presentation: Here, we report a case of granulomatous acanthamoebic encephalitis with a lethal outcome in a 54-year-old German man who was human immunodeficiency virus-positive. The diagnosis was based on symptoms of progressive neurological deficits, including sensorimotor paralysis of his right leg and deteriorating alertness. Due to the rapid course and rather late diagnosis of the infection, effective treatment could not be applied and he died 12 days after hospital admission.

Conclusions: To the best of our knowledge, this is the second case of granulomatous acanthamoebic encephalitis reported within Germany. Our case highlights the importance of early diagnosis of granulomatous acanthamoebic encephalitis to prevent fatal outcome.
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http://dx.doi.org/10.1186/s13256-018-1734-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6042392PMC
July 2018

Differential development of Legionella sub-populations during short- and long-term starvation.

Water Res 2018 09 11;141:417-427. Epub 2018 Apr 11.

Institute for Hygiene and Applied Immunology, Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria; Interuniversity Cooperation Centre for Water and Health, Austria. Electronic address:

Legionellae are among the most important waterborne pathogens in industrialized countries. Monitoring and surveillance of Legionella in engineered water systems is usually performed with culture-based methods. Since the advent of culture-independent techniques, it has become clear that Legionella concentrations are often several orders of magnitude higher than those measured by culture-based techniques and that a variable proportion of these non-culturable cells are viable. In engineered water systems, the formation of these viable but non-culturable (VBNC) cells can be caused by different kinds of stress, such as, and most importantly, nutrient starvation, oxidative stress and heat. In this study, the formation of VBNC cells of six Legionella strains under conditions of starvation was monitored in mono-species microcosms for up to one year using a combination of different viability indicators. Depending on the strain, complete loss of culturability was observed from 11 days to 8 weeks. During the starvation process, three distinct phases and different sub-populations of VBNC cells were identified. Until complete loss of culturability, the number of membrane-intact cells decreased rapidly to 5.5-69% of the initial cell concentration. The concentration of the sub-population with low esterase activity dropped to 0.03-55%, and the concentration of the highly esterase-active sub-population dropped to 0.01-1.2% of the initial concentration; these sub-populations remained stable for several weeks to months. Only after approximately 200 days of starvation, the number of VBNC cells started to decrease below detection limits. The most abundant VBNC sub-populations were characterized by partially damaged membranes and low esterase-activity. With this study, we showed that upon starvation, a stable VBNC Legionella community may be present over several months in a strain-dependent manner even under harsh conditions. Even after one year of starvation, a small proportion of L. pneumophila cells with high esterase-activity was detected. We speculate that this highly active VBNC subpopulation is able to infect amoebae and human macrophages.
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http://dx.doi.org/10.1016/j.watres.2018.04.027DOI Listing
September 2018

Mycoplasma hominis shows strain-dependent increase in resistance to selected antibiotics after symbiosis with Trichomonas vaginalis.

J Glob Antimicrob Resist 2018 09 13;14:169-175. Epub 2018 Apr 13.

Institute of Medical Microbiology and Hospital Hygiene, University Clinic of Heinrich Heine University, Düsseldorf, Germany.

Objectives: Mycoplasma hominis, a genetically heterogeneous, cell-wall-less bacterium, is able to live in symbiosis with the protozoan parasite Trichomonas vaginalis. Whilst the impact of this symbiosis on T. vaginalis has been investigated to a certain extent, less light has been shed on the influence on M. hominis.

Methods: An in vitro minimum inhibitory concentration (MIC) study of the antimicrobial susceptibility of three clinical M. hominis isolates (V475, AKH136 and MhSS10) to clindamycin, moxifloxacin, ciprofloxacin and gentamicin was performed in dependence on symbiosis with T. vaginalis strain IR78.

Results: Passaging of M. hominis through T. vaginalis led to an increase in MICs to all drugs investigated in M. hominis V475 and M. hominis MhSS10 (apart from gentamicin). Shifts from intermediate to resistant (MhSS10 for ciprofloxacin) and from susceptible to intermediate-resistant (V475 for gentamicin; P=0.015) were observed. Moreover, initial susceptibility of V475 to moxifloxacin (MIC=1.35μg/mL) was statistically significantly reduced (MIC=2.5μg/mL) following T. vaginalis passage concomitantly with mutations in the quinolone resistance-determining regions (QRDRs) of gyrA (S153L) and parC (E195G and K144R). In contrast, the susceptibility of M. hominis isolate AKH136 to all drugs investigated increased after passaging.

Conclusions: These findings suggest that symbiosis with T. vaginalis has an enhancing effect on selected antimicrobial resistances of distinct M. hominis isolates.
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http://dx.doi.org/10.1016/j.jgar.2018.04.003DOI Listing
September 2018

Soil protists: a fertile frontier in soil biology research.

FEMS Microbiol Rev 2018 05;42(3):293-323

Laboratory of Soil Biodiversity, University of Neuchâtel, Rue Emile-Argand 11, Neuchâtel 2000, Switzerland.

Protists include all eukaryotes except plants, fungi and animals. They are an essential, yet often forgotten, component of the soil microbiome. Method developments have now furthered our understanding of the real taxonomic and functional diversity of soil protists. They occupy key roles in microbial foodwebs as consumers of bacteria, fungi and other small eukaryotes. As parasites of plants, animals and even of larger protists, they regulate populations and shape communities. Pathogenic forms play a major role in public health issues as human parasites, or act as agricultural pests. Predatory soil protists release nutrients enhancing plant growth. Soil protists are of key importance for our understanding of eukaryotic evolution and microbial biogeography. Soil protists are also useful in applied research as bioindicators of soil quality, as models in ecotoxicology and as potential biofertilizers and biocontrol agents. In this review, we provide an overview of the enormous morphological, taxonomical and functional diversity of soil protists, and discuss current challenges and opportunities in soil protistology. Research in soil biology would clearly benefit from incorporating more protistology alongside the study of bacteria, fungi and animals.
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http://dx.doi.org/10.1093/femsre/fuy006DOI Listing
May 2018