Publications by authors named "Cindy Bethel"

18 Publications

  • Page 1 of 1

Sensitive detection and quantification of SARS-CoV-2 in saliva.

Sci Rep 2021 06 14;11(1):12425. Epub 2021 Jun 14.

Section of Hematology and Oncology, Pritzker School of Medicine, University of Chicago, Chicago, IL, USA.

Saliva has significant advantages as a test medium for detection of SARS-CoV-2 infection in patients, such as ease of collection, minimal requirement of supplies and trained personnel, and safety. Comprehensive validation in a large cohort of prospectively collected specimens with unknown SARS-CoV-2 status should be performed to evaluate the potential and limitations of saliva-based testing. We developed a saliva-based testing pipeline for detection of SARS-CoV-2 nucleic acids using real-time reverse transcription PCR (RT-PCR) and droplet digital PCR (ddPCR) readouts, and measured samples from 137 outpatients tested at a curbside testing facility and 29 inpatients hospitalized for COVID-19. These measurements were compared to the nasal swab results for each patient performed by a certified microbiology laboratory. We found that our saliva testing positively detects 100% (RT-PCR) and 93.75% (ddPCR) of curbside patients that were identified as SARS-CoV-2 positive by the Emergency Use Authorization (EUA) certified nasal swab testing assay. Quantification of viral loads by ddPCR revealed an extremely wide range, with 1 million-fold difference between individual patients. Our results demonstrate for both community screening and hospital settings that saliva testing reliability is on par with that of the nasal swabs in detecting infected cases, and has potential for higher sensitivity when combined with ddPCR in detecting low-abundance viral loads that evade traditional testing methods.
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http://dx.doi.org/10.1038/s41598-021-91835-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8203799PMC
June 2021

Implementation of a Sample Pooling Strategy for the Direct Detection of SARS-CoV-2 by Real-Time Polymerase Chain Reaction During the COVID-19 Pandemic.

Am J Clin Pathol 2021 06;156(1):15-23

Department of Pathology, Chicago, IL, USA.

Objectives: To report our institutional experience in devising and implementing a pooling protocol and process for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) testing over a 3-month period in the fall of 2020.

Methods: The widespread testing implemented in the United States for detecting SARS-CoV-2 infection in response to the coronavirus disease 2019 pandemic has led to a significant shortage of testing supplies and therefore has become a major impediment to the public health response. To date, several institutions have implemented sample pooling, but publications documenting these experiences are sparse. Nasal and nasopharyngeal samples collected from low-positivity (<5%) areas were tested in pools of five on the Roche cobas 6800 analyzer system. Routine SARS-CoV-2 RT-PCR turnaround times between sample collection to result reporting were monitored and compared before and after sample pooling implementation.

Results: A total of 4,131 sample pools were tested over a 3-month period (during which 39,770 RT-PCR results were reported from the Roche system), allowing our laboratory to save 13,824 tests, equivalent to a conservation rate of 35%. A 48-hour or less turnaround time was generally maintained throughout the pooling period.

Conclusions: Sample pooling offers a viable means to mitigate shortfalls of PCR testing supplies in the ongoing pandemic without significantly compromising overall turnaround times.
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http://dx.doi.org/10.1093/ajcp/aqab035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8136033PMC
June 2021

Effectiveness of facemasks for opening a university campus in Mississippi, United States - a modelling study.

J Am Coll Health 2021 Feb 19:1-6. Epub 2021 Feb 19.

Mississippi State University, Starkville, Mississippi, USA.

Universities are at risk for COVID-19 and Fall semester begins in August 2020 for most campuses in the United States. The Southern States, including Mississippi, are experiencing a high incidence of COVID-19. The objective of this study is to model the impact of face masks and hybrid learning on the COVID-19 epidemic on Mississippi State University (MSU) campus. We used an age structured deterministic mathematical model of COVID-19 transmission within the MSU campus population, accounting for asymptomatic transmission. We modeled facemasks for the campus population at varying proportions of mask use and effectiveness, and Hyflex model of partial online learning with reduction of people on campus. Facemasks can substantially reduce cases and deaths, even with modest effectiveness. Even 20% uptake of masks will halve the epidemic size. Facemasks combined with Hyflex reduces epidemic size even more. Universal use of face masks and reducing the number of people on campus may allow safer universities reopening.
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http://dx.doi.org/10.1080/07448481.2020.1866579DOI Listing
February 2021

Sensitive detection and quantification of SARS-CoV-2 in saliva.

medRxiv 2020 Dec 7. Epub 2020 Dec 7.

Saliva has significant advantages as a test medium for detection of SARS-CoV-2 infection in patients, such as ease of collection, minimal requirement of supplies and trained personnel, and safety. Comprehensive validation in a large cohort of prospectively collected specimens with unknown SARS-CoV-2 status should be performed to evaluate the potential and limitations of saliva-based testing. We developed a saliva-based testing pipeline for detection of SARS-CoV-2 nucleic acids using real-time reverse transcription PCR (RT-PCR) and droplet digital PCR (ddPCR) readouts, and measured samples from 137 outpatients tested at a curbside testing facility and 29 inpatients hospitalized for COVID-19. These measurements were compared to the nasal swab results for each patient performed by a certified microbiology laboratory. We found that our saliva testing positively detects 100% (RT-PCR) and 93.75% (ddPCR) of curbside patients that were identified as SARS-CoV-2 positive by the Emergency Use Authorization (EUA) certified nasal swab testing assay. Quantification of viral loads by ddPCR revealed an extremely wide range, with 1 million-fold difference between individual patients. Our results demonstrate for both community screening and hospital settings that saliva testing reliability is on par with that of the nasal swabs in detecting infected cases, and has potential for higher sensitivity when combined with ddPCR in detecting low-abundance viral loads that evade traditional testing methods.
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http://dx.doi.org/10.1101/2020.12.04.20241059DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7743089PMC
December 2020

From Etest to Vitek 2: Impact of Enterococcal Linezolid Susceptibility Testing Methodology on Time to Active Therapy.

Antimicrob Agents Chemother 2020 08 20;64(9). Epub 2020 Aug 20.

Department of Pathology, University of Chicago Medicine, Chicago, Illinois, USA.

Different linezolid antimicrobial susceptibility testing (AST) methodologies yield various results. In 2018, we transitioned our linezolid AST methodology from the Etest to Vitek 2. We sought to evaluate the impact of this change on antibiotic use among 181 inpatients with vancomycin-resistant enterococcal (VRE) infections. The transition from Etest to Vitek 2 resulted in an increase in linezolid susceptibility (38% versus 96%; < 0.001) and a reduction in time to active antibiotic therapy (3 versus 2.6 days; = 0.007).
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http://dx.doi.org/10.1128/AAC.00302-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449175PMC
August 2020

Evaluation of the EUROIMMUN Anti-SARS-CoV-2 ELISA Assay for detection of IgA and IgG antibodies.

J Clin Virol 2020 08 23;129:104468. Epub 2020 May 23.

Department of Pathology, University of Chicago, Chicago, IL 60637-1470, USA. Electronic address:

As the Coronavirus 2019 (COVID-19) pandemic evolves, the development of immunoassays to help determine exposure and potentially predict immunity has become a pressing priority. In this report we present the performance of the EUROIMMUN enzyme-linked immunosorbent assay (ELISA) for semi-quantitative detection of IgA and IgG antibodies in serum and plasma samples using recombinant S1 domain of the SARS-CoV-2 spike protein as antigen. Specimens from patients, with and without COVID-19 infection, were tested at the University of Chicago Clinical Microbiology and Immunology Laboratory. Of 86 samples from SARS-CoV-2 PCR-negative patients, including 28 samples positive for common human coronavirus strains, 76 tested negative and 10 tested positive for IgA (88.4% agreement, 95% CI: 79.9-93.6) while 84 tested negative and 2 tested positive for IgG (97.7% agreement, 95% CI: 91.9-99.6). Of 82 samples from SARS-CoV-2 PCR-positive patients, 14 tested negative and 68 tested positive for IgA (82.9% agreement, 95% CI: 73.4-89.5) while 27 tested negative and 55 tested positive for IgG (67.1% agreement, 95% CI: 56.3-76.3). Of samples collected ≥4 days after positive PCR, 38 of 42 (90.5% agreement, 95% CI: 77.9-96.2) were positive for IgA, and 42 of 42 (100% agreement, 95% CI: 91.6-100) were positive for IgG, respectively. The EUROIMMUN Anti-SARS-CoV-2 ELISA Assay demonstrated good sensitivity for detection of IgA and excellent sensitivity for detection of IgG antibodies from samples collected ≥4 days, after COVID-19 diagnosis by PCR. This assay demonstrated good specificity for IgA and excellent specificity for IgG and demonstrated only borderline cross reaction in 2 of the 28 samples from patients with common human coronaviruses infection, types NL63 and OC43.
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http://dx.doi.org/10.1016/j.jcv.2020.104468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7255182PMC
August 2020

Draft Genome Sequences of Two Acinetobacter baumannii Isolates from a Fatal Case of Necrotizing Fasciitis.

Microbiol Resour Announc 2020 Mar 26;9(13). Epub 2020 Mar 26.

Department of Microbiology, Miami University, Oxford, Ohio, USA

Carbapenem-resistant is a bacterial pathogen with serious implications for human health and is recognized as an urgent threat by the Centers for Disease Control and Prevention (CDC). Total DNA from two clinical isolates collected over 3 days from a fatal case of necrotizing fasciitis has been sequenced to >30× coverage.
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http://dx.doi.org/10.1128/MRA.00047-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7098894PMC
March 2020

Rapid pathogen identification and antimicrobial susceptibility testing in in vitro endophthalmitis with matrix assisted laser desorption-ionization Time-of-Flight Mass Spectrometry and VITEK 2 without prior culture.

PLoS One 2019 30;14(12):e0227071. Epub 2019 Dec 30.

Department of Ophthalmology and Visual Science, The University of Chicago Hospitals and Health System, Chicago, Illinois, United States of America.

Purpose: Prompt clinical diagnosis and initiation of treatment are critical in the management of infectious endophthalmitis. Current methods used to identify causative agents of infectious endophthalmitis are mostly inefficient, owing to suboptimal sensitivity, length, and cost. Matrix Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) can be used to rapidly identity pathogens without a need for culture. Similarly, automated antimicrobial susceptibility test systems (AST, VITEK 2) provide accurate antimicrobial susceptibility profiles. In this proof-of-concept study, we apply these technologies for the direct identification and characterization of pathogens in vitreous samples, without culture, as an in vitro model of infectious endophthalmitis.

Methods: Vitreous humor aspirated from freshly enucleated porcine eyes was inoculated with different inocula of Staphylococcus aureus (S. aureus) and incubated at 37°C. Vitreous endophthalmitis samples were centrifuged and pellets were directly analyzed with MALDI-TOF MS and VITEK 2 without prior culture. S. aureus colonies that were conventionally grown on culture medium were used as control samples. Time-to-identification, minimum concentration of bacteria required for identification, and accuracy of results compared to standard methods were determined.

Results: MALDI-TOF MS achieved accurate pathogen identification from direct analysis of intraocular samples with confidence values of up to 99.9%. Time from sample processing to pathogen identification was <30 minutes. The minimum number of bacteria needed for positive identification was 7.889x106 colony forming units (cfu/μl). Direct analysis of intraocular samples with VITEK 2 gave AST profiles that were up to 94.4% identical to the positive control S. aureus analyzed per standard protocol.

Conclusion: Our findings demonstrate that the direct analysis of vitreous samples with MALDI-TOF MS and VITEK 2 without prior culture could serve as new, improved methods for rapid, accurate pathogen identification and targeted treatment design in infectious endophthalmitis. In vivo models and standardized comparisons against other microbiological methods are needed to determine the value of direct analysis of intraocular samples from infectious endophthalmitis with MALDI-TOF MS and VITEK 2.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0227071PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6936829PMC
April 2020

Mice Fed an Obesogenic Western Diet, Administered Antibiotics, and Subjected to a Sterile Surgical Procedure Develop Lethal Septicemia with Multidrug-Resistant Pathobionts.

mBio 2019 07 30;10(4). Epub 2019 Jul 30.

Department of Surgery, University of Chicago, Chicago, Illinois, USA

Despite antibiotics and sterile technique, postoperative infections remain a real and present danger to patients. Recent estimates suggest that 50% of the pathogens associated with postoperative infections have become resistant to the standard antibiotics used for prophylaxis. Risk factors identified in such cases include obesity and antibiotic exposure. To study the combined effect of obesity and antibiotic exposure on postoperative infection, mice were allowed to gain weight on an obesogenic Western-type diet (WD), administered antibiotics and then subjected to an otherwise recoverable sterile surgical injury (30% hepatectomy). The feeding of a WD alone resulted in a major imbalance of the cecal microbiota characterized by a decrease in diversity, loss of , a bloom in , and the emergence of antibiotic-resistant organisms among the cecal microbiota. When WD-fed mice were administered antibiotics and subjected to 30% liver resection, lethal sepsis, characterized by multiple-organ damage, developed. Notable was the emergence and systemic dissemination of multidrug-resistant (MDR) pathobionts, including carbapenem-resistant, extended-spectrum β-lactamase-producing , which expressed a virulent and immunosuppressive phenotype. Analysis of the distribution of exact sequence variants belonging to the genus suggested that these strains originated from the cecal mucosa. No mortality or MDR pathogens were observed in identically treated mice fed a standard chow diet. Taken together, these results suggest that consumption of a Western diet and exposure to certain antibiotics may predispose to life-threating postoperative infection associated with MDR organisms present among the gut microbiota. Obesity remains a prevalent and independent risk factor for life-threatening infection following major surgery. Here, we demonstrate that when mice are fed an obesogenic Western diet (WD), they become susceptible to lethal sepsis with multiple organ damage after exposure to antibiotics and an otherwise-recoverable surgical injury. Analysis of the gut microbiota in this model demonstrates that WD alone leads to loss of , a bloom of , and evidence of antibiotic resistance development even before antibiotics are administered. After antibiotics and surgery, lethal sepsis with organ damage developed in in mice fed a WD with the appearance of multidrug-resistant pathogens in the liver, spleen, and blood. The importance of these findings lies in exposing how the selective pressures of diet, antibiotic exposure, and surgical injury can converge on the microbiome, resulting in lethal sepsis and organ damage without the introduction of an exogenous pathogen.
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http://dx.doi.org/10.1128/mBio.00903-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6667615PMC
July 2019

Prevalence of a Cefazolin Inoculum Effect Associated with Gene Types among Methicillin-Susceptible Staphylococcus aureus Isolates from Four Major Medical Centers in Chicago.

Antimicrob Agents Chemother 2018 08 27;62(8). Epub 2018 Jul 27.

Department of Pharmacy Practice, Midwestern University, Downers Grove, Illinois, USA.

The efficacy of cefazolin with high-inoculum methicillin-susceptible (MSSA) infections remains in question due to therapeutic failure inferred as being due to an inoculum effect (InE). This study investigated the local prevalence of a cefazolin InE (CInE) and its association with staphylococcal gene types among MSSA isolates in the Chicago area. Four medical centers in Chicago, IL, contributed MSSA isolates. Cefazolin MICs (C-MIC) were determined at 24 h by the broth microdilution method using a standard inoculum (SI; 5 × 10 CFU/ml) and a high inoculum (HI; 5 × 10 CFU/ml). The CInE was defined as (i) a ≥4-fold increase in C-MIC between SI and HI and/or (ii) a pronounced CInE, i.e., a nonsusceptible C-MIC of ≥16 μg/ml at HI. PCR was used to amplify the gene, followed by agarose gel electrophoresis and sequencing to determine the gene type. Approximately 269 MSSA isolates were included. All but one isolate were susceptible to cefazolin at SI, and 97% remained susceptible at HI. A total of 196 isolates (73%) were positive, with the types led by gene type C (40%). CInE was seen in 45 -positive isolates (23%), with 44 (22%) presenting a ≥4-fold increase in C-MIC (SI to HI) and 5 (3%) a pronounced CInE. Four of the five met both definitions of CInE, two of which expressed the type A gene. The prevalence of a pronounced CInE associated with the type A gene from MSSA isolates in Chicago is low. Our predilection for cefazolin use, even early in the management of hospitalized MSSA infections, is tenable.
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http://dx.doi.org/10.1128/AAC.00382-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105856PMC
August 2018

Use of the Accelerate Pheno System for Identification and Antimicrobial Susceptibility Testing of Pathogens in Positive Blood Cultures and Impact on Time to Results and Workflow.

J Clin Microbiol 2018 01 26;56(1). Epub 2017 Dec 26.

Clinical Microbiology Laboratory, Department of Pathology, University of Chicago Medicine, Chicago, Illinois, USA.

The Accelerate Pheno system uses automated fluorescence hybridization technology with morphokinetic cellular analysis to provide rapid species identification (ID) and antimicrobial susceptibility testing (AST) results for the most commonly identified organisms in bloodstream infections. The objective was to evaluate the accuracy and workflow of bacterial and yeast ID and bacterial AST using the Accelerate Pheno system in the clinical microbiology laboratory. The consecutive fresh blood cultures received in the laboratory were analyzed by the Accelerate Pheno system within 0 to 8 h of growth detection. ID/AST performance, the average times to results, and workflow were compared to those of the routine standard of care. Of the 232 blood cultures evaluated (223 monomicrobial and 9 polymicrobial) comprising 241 organisms, the overall sensitivity and specificity for the identification of organisms were 95.6% and 99.5%, respectively. For antimicrobial susceptibility, the overall essential agreement was 95.1% and categorical agreement was 95.5% compared to routine methods. There was one very major error and 3 major errors. The time to identification and the time to susceptibility using the Accelerate Pheno system were decreased by 23.47 and 41.86 h, respectively, compared to those for the standard of care. The reduction in hands on time was 25.5 min per culture. The Accelerate Pheno system provides rapid and accurate ID/AST results for most of the organisms found routinely in blood cultures. It is easy to use, reduces hands on time for ID/AST of common blood pathogens, and enables clinically actionable results to be released much earlier than with the current standard of care.
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http://dx.doi.org/10.1128/JCM.01166-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5744213PMC
January 2018

Collagen degradation and MMP9 activation by Enterococcus faecalis contribute to intestinal anastomotic leak.

Sci Transl Med 2015 May;7(286):286ra68

University of Chicago Pritzker School of Medicine, Chicago, IL 60637, USA.

Even under the most expert care, a properly constructed intestinal anastomosis can fail to heal, resulting in leakage of its contents, peritonitis, and sepsis. The cause of anastomotic leak remains unknown, and its incidence has not changed in decades. We demonstrate that the commensal bacterium Enterococcus faecalis contributes to the pathogenesis of anastomotic leak through its capacity to degrade collagen and to activate tissue matrix metalloproteinase 9 (MMP9) in host intestinal tissues. We demonstrate in rats that leaking anastomotic tissues were colonized by E. faecalis strains that showed an increased collagen-degrading activity and also an increased ability to activate host MMP9, both of which contributed to anastomotic leakage. We demonstrate that the E. faecalis genes gelE and sprE were required for E. faecalis-mediated MMP9 activation. Either elimination of E. faecalis strains through direct topical antibiotics applied to rat intestinal tissues or pharmacological suppression of intestinal MMP9 activation prevented anastomotic leak in rats. In contrast, the standard recommended intravenous antibiotics used in patients undergoing colorectal surgery did not eliminate E. faecalis at anastomotic tissues nor did they prevent leak in our rat model. Finally, we show in humans undergoing colon surgery and treated with the standard recommended intravenous antibiotics that their anastomotic tissues still contained E. faecalis and other bacterial strains with collagen-degrading/MMP9-activating activity. We suggest that intestinal microbes with the capacity to produce collagenases and to activate host metalloproteinase MMP9 may break down collagen in the intestinal tissue contributing to anastomotic leak.
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http://dx.doi.org/10.1126/scitranslmed.3010658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5027898PMC
May 2015

Prospective evaluation of the VITEK MS for the routine identification of bacteria and yeast in the clinical microbiology laboratory: assessment of accuracy of identification and turnaround time.

J Med Microbiol 2014 Feb 13;63(Pt 2):235-241. Epub 2013 Nov 13.

Department of Pathology, University of Chicago Medicine, 5841 S. Maryland Avenue, Chicago, IL 60637, USA.

This study assessed the accuracy of bacterial and yeast identification using the VITEK MS, and the time to reporting of isolates before and after its implementation in routine clinical practice. Three hundred and sixty-two isolates of bacteria and yeast, consisting of a variety of clinical isolates and American Type Culture Collection strains, were tested. Results were compared with reference identifications from the VITEK 2 system and with 16S rRNA sequence analysis. The VITEK MS provided an acceptable identification to species level for 283 (78 %) isolates. Considering organisms for which genus-level identification is acceptable for routine clinical care, 315 isolates (87 %) had an acceptable identification. Six isolates (2 %) were identified incorrectly, five of which were Shigella species. Finally, the time for reporting the identifications was decreased significantly after implementation of the VITEK MS for a total mean reduction in time of 10.52 h (P<0.0001). Overall, accuracy of the VITEK MS was comparable or superior to that from the VITEK 2. The findings were also comparable to other studies examining the accuracy of the VITEK MS, although differences exist, depending on the diversity of species represented as well as on the versions of the databases used. The VITEK MS can be incorporated effectively into routine use in a clinical microbiology laboratory and future expansion of the database should provide improved accuracy for the identification of micro-organisms.
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http://dx.doi.org/10.1099/jmm.0.063636-0DOI Listing
February 2014

Candida albicans isolates from the gut of critically ill patients respond to phosphate limitation by expressing filaments and a lethal phenotype.

PLoS One 2012 13;7(1):e30119. Epub 2012 Jan 13.

Department of Surgery, University of Chicago, Chicago, Illinois, United States of America.

Candida albicans is an opportunistic pathogen that proliferates in the intestinal tract of critically ill patients where it continues to be a major cause of infectious-related mortality. The precise cues that shift intestinal C. albicans from its ubiquitous indolent colonizing yeast form to an invasive and lethal filamentous form remain unknown. We have previously shown that severe phosphate depletion develops in the intestinal tract during extreme physiologic stress and plays a major role in shifting intestinal Pseudomonas aeruginosa to express a lethal phenotype via conserved phosphosensory-phosphoregulatory systems. Here we studied whether phosphate dependent virulence expression could be similarly demonstrated for C. albicans. C. albicans isolates from the stool of critically ill patients and laboratory prototype strains (SC5314, BWP17, SN152) were evaluated for morphotype transformation and lethality against C. elegans and mice during exposure to phosphate limitation. Isolates ICU1 and ICU12 were able to filament and kill C. elegans in a phosphate dependent manner. In a mouse model of intestinal phosphate depletion (30% hepatectomy), direct intestinal inoculation of C. albicans caused mortality that was prevented by oral phosphate supplementation. Prototype strains displayed limited responses to phosphate limitation; however, the pho4Δ mutant displayed extensive filamentation during low phosphate conditions compared to its isogenic parent strain SN152, suggesting that mutation in the transcriptional factor Pho4p may sensitize C. albicans to phosphate limitation. Extensive filamentation was also observed in strain ICU12 suggesting that this strain is also sensitized to phosphate limitation. Analysis of the sequence of PHO4 in strain ICU12, its transcriptional response to phosphate limitation, and phosphatase assays confirmed that ICU12 demonstrates a profound response to phosphate limitation. The emergence of strains of C. albicans with marked responsiveness to phosphate limitation may represent a fitness adaptation to the complex and nutrient scarce environment typical of the gut of a critically ill patient.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030119PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3258262PMC
May 2012

Outbreak of human adenovirus type 3 infection in a pediatric long-term care facility--Illinois, 2005.

Clin Infect Dis 2007 Aug 28;45(4):416-20. Epub 2007 Jun 28.

Chicago Department of Public Health, Chicago, IL 60612, USA.

Background: Human adenovirus type 3 (HAdV-3) causes severe respiratory illness in children, but outbreaks in long-term care facilities have not been frequently reported. We describe an outbreak of HAdV-3 infection in a long-term care facility for children with severe neurologic impairment, where only 3 of 63 residents were ambulatory.

Methods: A clinical case of HAdV-3 was defined as fever (temperature, > or = 38.0 degrees C) and either a worsening of respiratory symptoms or conjunctivitis in a resident, with illness onset from June through August 2005. We reviewed medical records; conducted surveillance for fever, conjunctivitis, and respiratory symptoms; and collected nasopharyngeal and conjunctival specimens from symptomatic residents. Specimens were cultured in HAdV-permissive cell lines or were analyzed by HAdV-specific polymerase chain reaction assay.

Results: Thirty-five (56%) of 63 residents had illnesses that met the case definition; 17 patients (49%) were admitted to intensive care units, and 2 (6%) died. Patients were hospitalized in the intensive care unit for a total of 233 patient-days. Illness onset dates ranged from 1 June through 24 August 2005. Thirty-two patients (91%) had respiratory infection, and 3 (9%) had conjunctivitis. HAdV was identified by culture or PCR in 20 patients. Nine isolates were characterized as HAdV-3 genome type a2.

Conclusions: Considering the limited mobility of residents and their reliance on respiratory care, transmission of HAdV-3 infection during this outbreak likely occurred through respiratory care provided by staff. In environments where patients with susceptible underlying conditions reside, HAdV infection should be considered when patients are identified with worsening respiratory disease, and rapid diagnostic tests for HAdV infection should be readily available to help identify and curtail the spread of this pathogen.
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http://dx.doi.org/10.1086/519938DOI Listing
August 2007

Identification of multi-drug resistant Pseudomonas aeruginosa clinical isolates that are highly disruptive to the intestinal epithelial barrier.

Ann Clin Microbiol Antimicrob 2006 Jun 8;5:14. Epub 2006 Jun 8.

Department of Surgery, University of Chicago, Chicago, USA.

Background: Multi-drug resistant Pseudomonas aeruginosa nosocomial infections are increasingly recognized worldwide. In this study, we focused on the virulence of multi-drug resistant clinical strains P. aeruginosa against the intestinal epithelial barrier, since P. aeruginosa can cause lethal sepsis from within the intestinal tract of critically ill and immuno-compromised patients via mechanisms involving disruption of epithelial barrier function.

Methods: We screened consecutively isolated multi-drug resistant P. aeruginosa clinical strains for their ability to disrupt the integrity of human cultured intestinal epithelial cells (Caco-2) and correlated these finding to related virulence phenotypes such as adhesiveness, motility, biofilm formation, and cytotoxicity.

Results: Results demonstrated that the majority of the multi-drug resistant P. aeruginosa clinical strains were attenuated in their ability to disrupt the barrier function of cultured intestinal epithelial cells. Three distinct genotypes were found that displayed an extreme epithelial barrier-disrupting phenotype. These strains were characterized and found to harbor the exoU gene and to display high swimming motility and adhesiveness.

Conclusion: These data suggest that detailed phenotypic analysis of the behavior of multi-drug resistant P. aeruginosa against the intestinal epithelium has the potential to identify strains most likely to place patients at risk for lethal gut-derived sepsis. Surveillance of colonizing strains of P. aeruginosa in critically ill patients beyond antibiotic sensitivity is warranted.
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http://dx.doi.org/10.1186/1476-0711-5-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1513249PMC
June 2006

Components of intestinal epithelial hypoxia activate the virulence circuitry of Pseudomonas.

Am J Physiol Gastrointest Liver Physiol 2005 May 18;288(5):G1048-54. Epub 2004 Nov 18.

Department of Surgery, University of Chicago, Chicago, Illinois 60637, USA.

We have previously shown that a lethal virulence trait in Pseudomonas aeruginosa, the PA-I lectin, is expressed by bacteria within the intestinal lumen of surgically stressed mice. The aim of this study was to determine whether intestinal epithelial hypoxia, a common response to surgical stress, could activate PA-I expression. A fusion construct was generated to express green fluorescent protein downstream of the PA-I gene, serving as a stable reporter strain for PA-I expression in P. aeruginosa. Polarized Caco-2 monolayers were exposed to ambient hypoxia (0.1-0.3% O2) for 1 h, with or without a recovery period of normoxia (21% O2) for 2 h, and then inoculated with P. aeruginosa containing the PA-I reporter construct. Hypoxic Caco-2 monolayers caused a significant increase in PA-I promoter activity relative to normoxic monolayers (165% at 1 h; P < 0.001). Similar activation of PA-I was also induced by cell-free apical, but not basal, media from hypoxic Caco-2 monolayers. PA-I promoter activation was preferentially enhanced in bacterial cells that physically interacted with hypoxic epithelia. We conclude that the virulence circuitry of P. aeruginosa is activated by both soluble and contact-mediated elements of the intestinal epithelium during hypoxia and normoxic recovery.
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http://dx.doi.org/10.1152/ajpgi.00241.2004DOI Listing
May 2005

Antimicrobial resistance in Staphylococcus aureus at the University of Chicago Hospitals: a 15-year longitudinal assessment in a large university-based hospital.

Infect Control Hosp Epidemiol 2003 Jun;24(6):403-8

Department of Pediatrics, Section of Pediatric Infectious Diseases, University of Chicago, Illinois, USA.

Objectives: To describe a longitudinal profile of resistance to beta-lactam antimicrobials among isolates of Staphylococcus aureus at a large university teaching hospital and to evaluate the impact of the methicillin resistance phenotype on resistance trends for non-beta-lactam antimicrobials.

Design: Retrospective evaluation of antimicrobial susceptibility data for all 17,287 S. aureus isolates obtained from January 1986 through December 2000.

Setting: The University of Chicago Hospitals, a family of tertiary-care, university-affiliated hospitals in Chicago, Illinois, consisting of 547 adult and pediatric beds.

Results: The annual rate of resistance to methicillin increased from 13% in 1986 to 28% in 2000 (P < .001) and has not plateaued. For each non-beta-lactam antimicrobial tested, the annual rates of resistance were far higher among methicillin-resistant S. aureus (MRSA) isolates than among methicillin-susceptible S. aureus (MSSA) isolates. The annual rates of resistance to the macrolide, lincosamide, and streptogramin (MLS) antimicrobials erythromycin and clindamycin increased among MSSA isolates (P < .01), but remained lower than 20%. Resistance to the MLS antimicrobials was higher among MRSA isolates (higher than 60%), but the annual rate decreased significantly during the study (P < .01).

Conclusion: The prevalence of methicillin resistance among S. aureus isolates has continued to increase; resistance to non-beta-lactam antimicrobials is far more common among MRSA isolates. Recent decreases in the proportion of MRSA isolates resistant to non-beta-lactam antimicrobials suggest important changes in the epidemiology of this pathogen.
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http://dx.doi.org/10.1086/502222DOI Listing
June 2003
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