Christopher F. Lowe

Outbreak of Extended-Spectrum β-Lactamase-producing Klebsiella oxytoca Infections Associated with Contaminated Handwashing Sinks 1

Sinks are a potential reservoir for environment-to-patient and patient-to-patient transmission.

mcr-1–Positive Colistin-Resistant Escherichia coli in Traveler Returning to Canada from China

To the Editor: A 61-year-old man underwent transurethral prostate resection in Vancouver, British Columbia, in January 2016. On postoperative day 1, he was febrile (39.1°C) and had leukocytosis (12.7 × 109 cells/L). Blood and urine cultures were ordered on postoperative day 2, and ceftriaxone was started. On postoperative day 3, urine culture grew Escherichia coli (>100 million CFU/L). Susceptibility testing (VITEK2, bioMerieux, Quebec, Canada) indicated a possible extended-spectrum β-lactamase producer and showed resistance to ampicillin, cefazolin, ceftriaxone, gentamicin, ciprofloxacin, and trimethoprim/sulfamethoxazole; intermediate resistance to tobramycin; and susceptibility to amoxicillin/clavulanate, piperacillin/tazobactam, ertapenem, meropenem, and nitrofurantoin. Treatment was switched to amoxicillin/clavulanate. The urinary catheter was removed 48 hours later. The patient was discharged on postoperative day 5 and completed 14 days of oral amoxicillin/clavulanate. Blood cultures were negative after 7 days’ incubation.

Antimicrobial stewardship for hospitalized patients with viral respiratory tract infections

Background The purpose of this study was to implement a targeted antimicrobial stewardship intervention for patients with a viral respiratory tract infection. Methods This was a quasi‐experimental before and after audit and feedback intervention of adult inpatients with a positive polymerase chain reaction for a respiratory virus in 2 acute care hospitals in Vancouver, Canada. Audit and feedback was implemented based on 2 criteria: microbiology (no positive bacterial cultures) and chest imaging (absence of pneumonia or consolidation on radiology dictation). A chart review was conducted to assess for days of antibiotics postviral diagnosis. Outcomes including length of stay, intensive care unit admission within 14 days, mechanical ventilation within 14 days, antibiotics prescribed within 14 days, Clostridium difficile infection diagnosed within 30 days, and readmission within 30 days were also reviewed in comparison with the previous year. Results Antimicrobial stewardship recommendations for hospitalized patients with viral respiratory tract infections were accepted for 77% of cases. This targeted approach based on easily assessed parameters translated into a 1.3‐day (95% confidence interval, 0.3‐2.3; P < .01) decrease in mean days of antibiotics postviral diagnosis compared with the previous year without systematic interventions. Compared with the previous year, no differences were identified for adverse outcomes associated with the intervention. Conclusions A targeted antimicrobial stewardship intervention integrating virology testing with the treating physician facilitated a reduction in duration of antibiotic treatment for viral respiratory tract infections.

Implementation of Next-Generation Sequencing for Hepatitis B Virus Resistance Testing and Genotyping in a Clinical Microbiology Laboratory

ABSTRACT Sanger sequencing or DNA hybridization have been the primary modalities for hepatitis B (HBV) resistance testing and genotyping; however, there are limitations, such as low sensitivity and the inability to detect novel mutations. Next-generation sequencing (NGS) for HBV can overcome these limitations, but there is limited guidance for clinical microbiology laboratories to validate this novel technology. In this study, we describe an approach to implementing deep pyrosequencing for HBV resistance testing and genotyping in a clinical virology laboratory. A nested PCR targeting the pol region of HBV (codons 143 to 281) was developed, and the PCR product was sequenced by the 454 Junior (Roche). Interpretation was performed by ABL TherapyEdge based on European Association for the Study of the Liver (EASL) guidelines. Previously characterized HBV samples by INNO-LiPA (LiPA) were compared to NGS with discordant results arbitrated by Sanger sequencing. Genotyping of 105 distinct samples revealed a concordance of 95.2% (100/105), with Sanger sequencing confirming the NGS result. Resistance testing by NGS was concordant with LiPA in 85% (68/80) of previously characterized samples. Additional mutations were found in 8 samples, which related to the identification of low-level mutant subpopulations present at <10% (6/8). To balance the costs of testing for the validation study, reproducibility of the NGS was investigated through an analysis of sequence variants at loci not associated with resistance in a single patient sample. Our validation approach attempts to balance costs with efficient data acquisition.

Hospital-associated transmission of Brucella melitensis outside the laboratory.

Brucella melitensis was identified in an aspirate obtained from a patient’s hip joint during a procedure at a hospital in Canada. We conducted an investigation into possible exposures among hospital workers; 1 worker who assisted with the procedure tested positive for B. melitensis. Aerosol-generating procedures performed outside the laboratory may facilitate transmission of this bacterium.

Reduction in hospital-associated methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus with daily chlorhexidine gluconate bathing for medical inpatients

Background: Daily bathing with chlorhexidine gluconate (CHG) is increasingly used in intensive care units to prevent hospital‐associated infections, but limited evidence exists for noncritical care settings. Methods: A prospective crossover study was conducted on 4 medical inpatient units in an urban, academic Canadian hospital from May 1, 2014‐August 10, 2015. Intervention units used CHG over a 7‐month period, including a 1‐month wash‐in phase, while control units used nonmedicated soap and water bathing. Rates of hospital‐associated methicillin‐resistant Staphylococcus aureus (MRSA) and vancomycin‐resistant Enterococcus (VRE) colonization or infection were the primary end point. Hospital‐associated S. aureus were investigated for CHG resistance with a qacA/B and smr polymerase chain reaction (PCR) and agar dilution. Results: Compliance with daily CHG bathing was 58%. Hospital‐associated MRSA and VRE was decreased by 55% (5.1 vs 11.4 cases per 10,000 inpatient days, P = .04) and 36% (23.2 vs 36.0 cases per 10,000 inpatient days, P = .03), respectively, compared with control cohorts. There was no significant difference in rates of hospital‐associated Clostridium difficile. Chlorhexidine resistance testing identified 1 isolate with an elevated minimum inhibitory concentration (8 &mgr;g/mL), but it was PCR negative. Conclusions: This prospective pragmatic study to assess daily bathing for CHG on inpatient medical units was effective in reducing hospital‐associated MRSA and VRE. A critical component of CHG bathing on medical units is sustained and appropriate application, which can be a challenge to accurately assess and needs to be considered before systematic implementation.

Management of a Concurrent Influenza A and Parainfluenza 1 Outbreak in a Residential Care Facility

Conflict of Interest: Dr. Nancy Schoenborn has received a 2016 New Investigator Award from the American Geriatrics Society/Merck. These awards are selected by the American Geriatrics Society but are supported by an educational grant from Merck Sharp & Dohme. We do not believe this has resulted in any conflict with the design, methodology, or results presented in this manuscript. This project was made possible in part through the support of the Maryland Cigarette Restitution Fund Research Grant to the Johns Hopkins Medical Institutions. The project was also supported by the John A. Hartford Foundation Geriatric Center of Excellence, the Daniel and Jeannette Hendin Schapiro Geriatric Medical Education Center. Dr. Boyd was also supported by Paul Beeson Career Development Award NIA K23 AG032910, the John A. Hartford Foundation, Atlantic Philanthropies, and the Starr Foundation. Mr. Bowman was support by the Medical Student Training in Aging Research program. Dr. Pollack was supported by National Cancer Institute Career Development Award K07CA151910. An earlier version of the manuscript was presented as a poster at the American Geriatrics Society national meeting, Long Beach, California, May 19–21, 2016. Author Contributions: Dr. Schoenborn had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Schoenborn N. L., Pollack C. E., Cayea D., Feeser S., Boyd C.: study design and conduct. Schoenborn N. L.: data collection and management. Schoenborn N. L., Bowman T., Pollack C. E., Cayea D., Feeser S., Boyd C.: data analysis and interpretation. Schoenborn C. E., Bowman T.: preparation of manuscript. Schoenborn N. L., Bowman T., Pollack C. E., Cayea D., Feeser S., Boyd C.: review and revision of manuscript. Sponsor’s Role: The funding sources had no role in the design, methods, subject recruitment, data collections, analysis, and preparation of paper.

Nasal photodisinfection and chlorhexidine: post hoc ergo propter hoc?

Recently, Bryce et al. asserted that the combination of photodisinfection therapy (PDT) and chlorhexidine (CHG) bathing can reduce surgical site infections (SSIs). Nasal PDT appears to be an attractive technology; however, further studies are needed beyond an observational study design with a post-hoc propensity score analysis to show the utility and effectiveness of this technology, with or without CHG bathing, in preventing SSIs. While it may be very important to obtain a sufficient sample size for this type of study, comparing a one-year post-intervention SSI rate with a four-year historical average SSI rate across multiple surgical subspecialties is fraught with multiple sources of error and confounding. Studies using historical controls are biased in favour of the experimental treatment or intervention; this bias cannot be overcome by a post-hoc propensity analysis. When the time period between the control and experimental groups is substantial (e.g. five years), before and after groups are typically not comparable, especially when SSI clusters have occurred, when other interventions were used selectively (e.g. mupirocin prophylaxis), or when other broadly impactful interventions were implemented concurrently (e.g. institutional hand hygiene campaign). Over time, surgical techniques improve, compliance with surgical bundles may increase, and surveillance programmes are modified. Due to these potential confounders, caution should be used in interpreting single-centre observational studies. The relative impact of CHG vs PDT in preventing SSIs could also be debated in the absence of a randomized controlled trial. When two interventions are combined, the independent impact of each intervention is unknown. In this case, the decrease in SSI rate could be explained entirely by CHG rather than its combination with PDT.

Transitioning cytomegalovirus viral load testing from a laboratory developed test to the cobas® CMV quantitative nucleic acid assay

Commutability between human cytomegalovirus (CMV) viral load assays (VLA) is poor, despite the development of a WHO CMV International Standard (CMV IS). We evaluated a new CMV VLA, cobas® CMV, as compared to our current laboratory developed CMV VLA (LDT), for clinical use. Both the LDT and cobas® CMV were run in parallel for 109 patient samples. In addition, 104 replicates, over 8 dilutions, of the CMV IS were tested. Conversion factors and correlation between the two assays were calculated. The correlation coefficient between the LDT and cobas® CMV was 0.91 for patient samples. The Bland‐Altman graph displayed a systematic bias of +0.31 log10 for the cobas® CMV as compared to the LDT. The bias was greater for lower CMV viral loads. This increase in CMV viral loads was not seen with testing of the CMV IS dilutions by both the LDT and cobas® CMV. CMV VLA inter‐assay commutability continues to be an issue when switching CMV testing platforms and requires communication between the laboratory and clinicians during the transition period to prevent misinterpretation of results.

Evaluation of the FilmArray Blood Culture Identification Panel compared to direct MALDI-TOF MS identification for rapid identification of pathogens

To improve time to identification of pathogens and detection of resistance genes, we evaluated the BioFire FilmArray Blood Culture Identification Panel (BCID) as compared to: (1) direct MALDI-TOF MS (DM) and (2) standardized culture-based identification (ID) with antibiotic susceptibility testing (AST). BCID gave an accurate identification in 102/112 (91 %) of cases (102/103 for on-panel organisms). DM gave an accurate identification in 91/112 (81 %) of cases, with 13/91 (14 %) requiring repeat testing from the residual pellet. The mean time to an identification result was 2.4 and 2.9 h for BCID and DM, respectively. Standardized ID and AST results were available at a mean time of 26.5 and 33 h, respectively. There were 44 BCID/DM results that had an antimicrobial treatment change made based on rapid identification and resistant gene detection of pathogens. Both BCID and DM are accurate and rapid methods for the identification of new positive blood culture pathogens.