C.W. Bradley

Genomic epidemiology of a protracted hospital outbreak caused by multidrug-resistant Acinetobacter baumannii in Birmingham, England

BackgroundMultidrug-resistant Acinetobacter baumannii commonly causes hospital outbreaks. However, within an outbreak, it can be difficult to identify the routes of cross-infection rapidly and accurately enough to inform infection control. Here, we describe a protracted hospital outbreak of multidrug-resistant A. baumannii, in which whole-genome sequencing (WGS) was used to obtain a high-resolution view of the relationships between isolates.MethodsTo delineate and investigate the outbreak, we attempted to genome-sequence 114 isolates that had been assigned to the A. baumannii complex by the Vitek2 system and obtained informative draft genome sequences from 102 of them. Genomes were mapped against an outbreak reference sequence to identify single nucleotide variants (SNVs).ResultsWe found that the pulsotype 27 outbreak strain was distinct from all other genome-sequenced strains. Seventy-four isolates from 49 patients could be assigned to the pulsotype 27 outbreak on the basis of genomic similarity, while WGS allowed 18 isolates to be ruled out of the outbreak. Among the pulsotype 27 outbreak isolates, we identified 31 SNVs and seven major genotypic clusters. In two patients, we documented within-host diversity, including mixtures of unrelated strains and within-strain clouds of SNV diversity. By combining WGS and epidemiological data, we reconstructed potential transmission events that linked all but 10 of the patients and confirmed links between clinical and environmental isolates. Identification of a contaminated bed and a burns theatre as sources of transmission led to enhanced environmental decontamination procedures.ConclusionsWGS is now poised to make an impact on hospital infection prevention and control, delivering cost-effective identification of routes of infection within a clinically relevant timeframe and allowing infection control teams to track, and even prevent, the spread of drug-resistant hospital pathogens.

Improved understanding of an outbreak of meticillin-resistant Staphylococcus aureus in a regional burns centre via whole-genome sequencing

Journal of Hospital Infection - In Press.Proof corrected by the author Available online since dimanche 9 octobre 2016

Engineering waterborne Pseudomonas aeruginosa out of a critical care unit

OBJECTIVE To describe engineering and holistic interventions on water outlets contaminated with Pseudomonas aeruginosa and the observed impact on clinical P. aeruginosa patient isolates in a large Intensive Care Unit (ICU). DESIGN Descriptive study. SETTING Queen Elizabeth Hospital Birmingham (QEHB), part of University Hospitals Birmingham (UHB) NHS Foundation Trust is a tertiary referral teaching hospital in Birmingham, UK and provides clinical services to nearly 1 million patients every year. METHODS Breakpoint models were used to detect any significant changes in the cumulative yearly rates of clinical P. aeruginosa patient isolates from August 2013-December 2016 across QEHB. RESULTS Water sampling undertaken on the ICU indicated 30% of the outlets were positive for P. aeruginosa at any one time. Molecular typing of patient and water isolates via Pulsed Field Gel Electrophoresis suggested there was a 30% transmission rate of P. aeruginosa from the water to patients on the ICU. From, February 2014, QEHB implemented engineering interventions, consisting of new tap outlets and PALL point-of-use filters; as well as holistic measures, from February 2016 including a revised tap cleaning method and appropriate disposal of patient waste water. Breakpoint models indicated the engineering and holistic interventions resulted in a significant (p<0.001) 50% reduction in the number of P. aeruginosa clinical patient isolates over a year. CONCLUSION Here we demonstrate that the role of waterborne transmission of P. aeruginosa in an ICU cannot be overlooked. We suggest both holistic and environmental factors are important in reducing transmission.

A Year in the Life of a Contaminated Heater-Cooler Unit With Mycobacterium chimaera?

OBJECTIVE Heater-cooler units (HCUs) have been shown to be a source of Mycobacterium chimaera infections. For the past year, weekly water samples have been taken from HCUs used at University Hospitals Birmingham (UHB) NHS Foundation Trust. We report the microbial contamination of the HCUs over a year detailing the decontamination regimes applied at UHB to reduce the microbial load. DESIGN Observational study SETTING UHB is a tertiary referral teaching hospital in Birmingham, United Kingdom, that provides clinical services to nearly 1 million patients every year. The UHB Cardiac department is one of the largest in the United Kingdom and provides treatment for adult patients with a wide range of cardiac diseases. METHODS Water samples taken from HCUs used at UHB for cardiopulmonary bypass surgery were sampled over a year to determine the number of microorganisms by membrane filtration. Various decontamination processes were employed throughout the year. RESULTS Varying total viable counts containing a wide variety of microorganisms were obtained from water inside the HCUs. No M. chimaera were isolated after replacement of the HCU internal tubing. Stringent decontamination regimes resulted in degradation of the HCUs and increased TVCs after several months. CONCLUSION More work is required to ensure effective decontamination processes to reduce the microbial load within the HCUs. Our studies indicate that weekly water sampling for TVC will be required indefinitely to monitor the water quality in these units as well as regular replacement of the tubing to control the build-up of biofilm. Infect Control Hosp Epidemiol 2017;38:705-711.

Using a carbapenemase-producing organism polymerase chain reaction to rapidly determine the efficacy of terminal room disinfection

We recently reported that a standard terminal clean including hydrogen peroxide vapour at a concentration of 6%, as well as disinfection using 1000 ppm hypochlorite, did not remove carbapenemase-producing organisms (CPOs) from the environment. Our report prompted a debate in this Journal focusing on the lack of evidence for the best means of terminally cleaning and disinfecting areas occupied by patients with CPOs. Our paper went on to describe a more enhanced clean, comprising detergent, steam, and double-strength hypochlorite cleans followed by hydrogen peroxide misting. At each stage, environmental sampling was carried out on multiple macroscopically clean touch-points in an effort to detect CPOs. However, culture-based screening with the need for overnight incubation introduces delays if a negative result is required before the bed space is reopened. In the current report, we continue on the work previously described, and detail how we quickly identified that a bed area was contaminated with a CPO using a CPO polymerase chain reaction (PCR); this enabled an earlier, further enhanced, clean to be undertaken, and quicker turnaround of the bed space for another patient. University Hospitals Birmingham NHS Foundation Trust is a secondary and tertiary care teaching hospital in Birmingham, UK, that provides clinical services to nearly one million patients every year. A patient with no known risk factors for CPO carriage was admitted to the critical care unit, and, during admission, a Klebsiella pneumoniae carbapenemase (KPC)producing strain of Enterobacter cloacae was isolated from a drain specimen. The patient was initially located in an open bed-space and was moved into isolation following identification of the CPO. The bed space underwent terminal cleaning, after which an infection prevention and control nurse deemed it to be visually clean. Environmental sampling was undertaken as previously described. Briefly, MW729 Polywipe sponges (Medical Wire & Equipment Co. Ltd, Corsham, UK) were used to sample multiple macroscopically clean touchpoints throughout the bed area immediately after the

Waterborne Pseudomonas aeruginosa transmission in a hematology unit

Background: Pseudomonas aeruginosa is an important nosocomial pathogen that commonly colonizes hospital water supplies, including in taps and sinks. We report the transmission of P. aeruginosa from water to patients in a clinical hematology setting. Methods: P. aeruginosa from water samples were compared to clinical isolates from hematology ward patients, via molecular typing (pulsed field gel electrophoresis). Results: P. aeruginosa cultured from blood cultures from 3 patients was indistinguishable from water strains, by molecular typing. Based on infection control inspections, the transmission event was surmised to be due to cleaning of equipment, specifically an infusion therapy procedure tray used to transport intravenous drugs to patients, with water from an outlet colonized by P. aeruginosa. Conclusion: We show the importance of holistic factors, such as disposal of patient waste water, cleaning of tap outlets, and cleaning of medical equipment, in the transmission of P. aeruginosa, and demonstrate that the role of waterborne transmission of this organism in a hematology setting cannot be overlooked. We suggest that appropriate management of water, including both holistic and engineering interventions, is needed to stop transmission of P. aeruginosa from water to patients.

Use of genome sequencing to identify hepatitis C virus transmission in a renal healthcare setting

BACKGROUND Hepatitis C virus (HCV) infection is a major health burden worldwide. A patient with no history of HCV infection while on a renal unit was found to seroconvert to HCV. AIM To report the use of sequencing to postulate how transmission of HCV occurred in a healthcare setting, and how this guided our outbreak investigation. FINDINGS Based on infection control inspections the transmission event was surmised to be due to ward environmental contamination with blood and subsequent inoculation from intravenous interventions on the patient acquiring HCV. We discuss the interventions put in place in response to the outbreak investigation findings. CONCLUSION Sequencing of healthcare-acquired HCV infections should be undertaken as routine practice in outbreak investigations.

Decontamination of an Extracorporeal Membrane Oxygenator Contaminated With Mycobacterium chimaera

Water samples taken from extracorporeal membrane oxygenator (ECMO) devices used at University Hospitals Birmingham yielded high total viable counts (TVCs) containing a variety of microorganisms, including M. chimaera. Disinfection resulted in the reduction of TVCs and eradication of Mycobacterium chimaera. Weekly disinfection and water sampling are required to manage the water quality in these devices. Infect Control Hosp Epidemiol 2017;38:1244-1246.

The Effect of Universal Decolonization With Screening in Critical Care to Reduce MRSA Across an Entire Hospital

OBJECTIVE To describe the effect of universal methicillin-resistant Staphylococcus aureus (MRSA) decolonization therapy in a large intensive care unit (ICU) on the rates of MRSA cases and acquisitions in a UK hospital. DESIGN Descriptive study. SETTING University Hospitals Birmingham (UHB) NHS Foundation Trust is a tertiary referral teaching hospital in Birmingham, United Kingdom, that provides clinical services to nearly 1 million patients every year. METHODS A break-point time series analysis and kernel regression models were used to detect significant changes in the cumulative monthly numbers of MRSA bacteremia cases and acquisitions from April 2013 to August 2016 across the UHB system. RESULTS Prior to 2014, all ICU patients at UHB received universal MRSA decolonization therapy. In August 2014, UHB discontinued the use of universal decolonization due to published reports in the United Kingdom detailing the limited usefulness and cost-effectiveness of such an intervention. Break-point time series analysis of MRSA acquisition and bacteremia data indicated that break points were associated with the discontinuation and subsequent reintroduction of universal decolonization. Kernel regression models indicated a significant increase (P<.001) in MRSA acquisitions and bacteremia cases across UHB during the period without universal decolonization. CONCLUSION We suggest that routine decolonization for MRSA in a large ICU setting is an effective strategy to reduce the spread and incidence of MRSA across the whole hospital. Infect Control Hosp Epidemiol 2017;38:430-435.

Outbreak of clonal complex 22 Panton–Valentine leucocidin-positive methicillin-resistant Staphylococcus aureus:

Aims: We describe the investigation and control of a nosocomial outbreak of Sequence Type (ST) 22 MRSA containing the Panton–Valentine leucocidin (PVL) toxin in an acute multispecialty surgical ward at University Hospital Birmingham NHS Foundation Trust. Methods: A patient was classed as acquiring methicillin-resistant Staphylococcus aureus (MRSA) if they had a negative admission screen and then had MRSA isolated from a subsequent screen or clinical specimen. Spa typing and pulsed field gel electrophoresis (PFGE) was undertaken to confirm MRSA acquisitions. Findings: The Infection Prevention and Control Team were alerted to the possibility of an outbreak when two patients acquired MRSA while being on the same ward. In total, five patients were involved in the outbreak where four patients acquired the PVL-MRSA clone from an index patient due to inadequate infection control practice. Two patients who acquired the strain developed a bloodstream infection. Infection control measures included decolonisation of affected patients, screening of all patients on the ward, environmental sampling and enhanced cleaning. Discussion: Our study highlights the potential risk of spread and pathogenicity of this clone in the healthcare setting. Spa typing and PFGE assisted with confirmation of the outbreak and implementation of infection control measures. In outbreaks, microbiological typing should be undertaken as a matter of course as without specialist typing identification of the described outbreak would have been delayed.