Serological responses to SARS-CoV-2 following non-hospitalised infection: clinical and ethnodemographic features associated with the magnitude of the antibody response.

OBJECTIVE: To determine clinical and ethnodemographic correlates of serological responses against the SARS-CoV-2 spike glycoprotein following mild-to-moderate COVID-19. DESIGN: A retrospective cohort study of healthcare workers who had self-isolated due to COVID-19. SETTING: University Hospitals Birmingham NHS Foundation Trust, UK (UHBFT). PARTICIPANTS: 956 health care workers were recruited by open invitation via UHBFT trust email and social media. INTERVENTION: Participants volunteered a venous blood sample that was tested for the presence of anti-SARS-CoV-2 spike glycoprotein antibodies. Results were interpreted in the context of the symptoms of their original illness and ethnodemographic variables. RESULTS: Using an assay that simultaneously measures the combined IgG, IgA and IgM response against the spike glycoprotein (IgGAM), the overall seroprevalence within this cohort was 46.2% (n=442/956). The seroprevalence of immunoglobulin isotypes was 36.3%, 18.7% and 8.1% for IgG, IgA and IgM respectively. IgGAM identified serological responses in 40.6% (n=52/128) of symptomatic individuals who reported a negative SARS-CoV-2 PCR test. Increasing age, non-white ethnicity and obesity were independently associated with greater IgG antibody response against the spike glycoprotein. Self-reported fever and fatigue were associated with greater IgG and IgA responses against the spike glycoprotein. The combination of fever and/or cough and/or anosmia had a positive predictive value of 92.3% for seropositivity. CONCLUSIONS AND RELEVANCE: Assays employing combined antibody detection demonstrate enhanced seroepidemiological sensitivity and can detect prior viral exposure even when PCR swabs have been negative. We demonstrate an association between known ethnodemographic risk factors associated with mortality from COVID-19 and the magnitude of serological responses in mild-to-moderate disease. The combination of cough, and/or fever and/or anosmia identifies the majority of individuals who should self-isolate for COVID-19.

Impact of a PCR point of care test for influenza A/B on an acute medical unit in a large UK teaching hospital: results of an observational, pre and post intervention study.

Background: Influenza viruses is a leading cause of acute respiratory infection, placing a significant burden on healthcare. To reduce hospital transmission, patients clinically suspected of having influenza are isolated and offered empirical antiviral treatment. Here we report the use of a point of care test (POCT) for influenza viruses in an acute medical unit (AMU) at Queen Elizabeth Hospital Birmingham for patients presenting with influenza-like illness. Methods: A PCR POCT was installed on AMU in Dec 17 - Mar 18 (period 2) and used to test any patient with influenza-like illness. We conducted an evaluation against influenza virus's data collected between Dec 16-Mar 17 (period 1) where no POCT was used. Four outcomes were measured: length of stay, oseltamivir utilisation, time to isolation and in-hospital cases of influenza viruses. Results: There were 51 confirmed influenza virus cases in period 1 vs 666 in period 2. During period 2, the length of stay of patients presenting with influenza-like illness (2.4 vs 7.9 days) and time to isolation from receipt of a positive result (0.09 vs 1.26 days) was significantly shorter. The time to initial receipt of antivirals for patients with influenza virus was significantly quicker in period 2 (0.59 vs 1.1 days) and the total number of influenza virus cases identified after 72 h of admission was significantly lower (9% vs 51%). Discussion: Following introduction of the POCT, there was an increase in appropriately targeted oseltamivir prescribing, shorter time to isolation, proportionally less post-72-h influenza virus cases and a reduction in length of stay of patients presenting with influenza-like illness. Conclusions: Routine use of POCTs for viruses should be introduced into diagnostic pathways for acute respiratory illness, especially at the front door of hospitals.

The value of the infection prevention and control nurse led MRSA ward round.

Meticillin-resistant S. aureus (MRSA) is prevalent in most parts of the world. The study took place at Queen Elizabeth Hospital Birmingham (QEHB) a UK tertiary referral hospital. At QEHB innovative nurse led daily ward rounds for patients that acquire hospital acquired MRSA during their hospital stay are undertaken. The aim is to optimise care delivered for these patients whilst at QEHB, thereby reducing the risk of infection in patients with healthcare-acquired MRSA. A segmented Poisson regression model suggests that the MRSA bacteraemia rate was affected where an 88.94% reduction (p = 0.0561) in bacteraemias was seen by the introduction of these ward rounds. We describe a nurse led MRSA ward round which was associated with a lower rate of MRSA bacteraemias.

Wiping out MRSA: effect of introducing a universal disinfection wipe in a large UK teaching hospital.

Background: Contamination of the inanimate environment around patients constitutes an important reservoir of MRSA. Here we describe the effect of introducing a universal disinfection wipe in all wards on the rates of MRSA acquisitions and bacteraemias across a large UK teaching hospital. Methods: A segmented Poisson regression model was used to detect any significant changes in the monthly numbers per 100,000 bed days of MRSA acquisitions and bacteraemias from April 2013 - December 2017 across QEHB. Results: From April 2013 to April 2016, cleaning of ward areas and multi-use patient equipment by nursing staff consisted of a two-wipe system. Firstly, a detergent wipe was used, which was followed by a disinfection step using an alcohol wipe. In May 2016, QEHB discontinued the use of a two-wipe system for cleaning and changed to a one wipe system utilising a combined cleaning and disinfection wipe containing a quaternary ammonium compound. The segmented Poisson regression model demonstrated that the rate of MRSA acquisition/100,000 patient bed days was affected by the introduction of the new wiping regime (20.7 to 9.4 per 100,000 patient bed days; p <0.005). Discussion: Using a Poisson model we demonstrated that the average hospital acquisition rate of MRSA/100,000 patient bed days reduced by 6.3% per month after the introduction of the new universal wipe. Conclusion: We suggest that using a simple one wipe system for nurse cleaning is an effective strategy to reduce the spread and incidence of healthcare associated MRSA.

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.

Can a toxin gene NAAT be used to predict toxin EIA and the severity of Clostridium difficile infection?

Background: Diagnosis of C. difficile infection (CDI) is controversial because of the many laboratory methods available and their lack of ability to distinguish between carriage, mild or severe disease. Here we describe whether a low C. difficile toxin B nucleic acid amplification test (NAAT) cycle threshold (CT) can predict toxin EIA, CDI severity and mortality. Methods: A three-stage algorithm was employed for CDI testing, comprising a screening test for glutamate dehydrogenase (GDH), followed by a NAAT, then a toxin enzyme immunoassay (EIA). All diarrhoeal samples positive for GDH and NAAT between 2012 and 2016 were analysed. The performance of the NAAT CT value as a classifier of toxin EIA outcome was analysed using a ROC curve; patient mortality was compared to CTs and toxin EIA via linear regression models. Results: A CT value ≤26 was associated with ≥72% toxin EIA positivity; applying a logistic regression model we demonstrated an association between low CT values and toxin EIA positivity. A CT value of ≤26 was significantly associated (p = 0.0262) with increased one month mortality, severe cases of CDI or failure of first line treatment. The ROC curve probabilities demonstrated a CT cut off value of 26.6. Discussions: Here we demonstrate that a CT ≤26 indicates more severe CDI and is associated with higher mortality. Samples with a low CT value are often toxin EIA positive, questioning the need for this additional EIA test. Conclusions: A CT ≤26 could be used to assess the potential for severity of CDI and guide patient treatment.

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.

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.

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.

Reduction in methicillin-resistant Staphylococcus aureus colonisation: impact of a screening and decolonisation programme.

Patients in care homes are often at 'high risk' of being methicillin-resistant Staphylococcus aureus (MRSA) colonised. Here we report the prevalence of MRSA, the effect of MRSA screening and decolonisation in Wolverhampton care-home residents. Eighty-two care homes (1665 residents) were screened for MRSA, three times at 6-monthly intervals (referred to as phases one, two and three). Screening and decolonisation of MRSA-colonised residents led to a reduction in the prevalence of MRSA from 8.7% in phase one, 6.3% in phase 2 and 4.7% in phase three. Overall, the study suggests that care-home facilities in Wolverhampton are a significant reservoir for MRSA; screening and decolonisation has reduced the risk to residents going for procedures and has indirectly impacted on MRSA rates in the acute Trust.

Medicinal plant extracts with efflux inhibitory activity against Gram-negative bacteria.

It was hypothesised that extracts from plants that are used as herbal medicinal products contain inhibitors of efflux in Gram-negative bacteria. Extracts from 21 plants were screened by bioassay for synergy with ciprofloxacin against Salmonella enterica serotype Typhimurium, including mutants in which acrB and tolC had been inactivated. The most active extracts, fractions and purified compounds were further examined by minimum inhibitory concentration testing with five antibiotics for activity against Enterobacteriaceae and Pseudomonas aeruginosa. Efflux activity was determined using the fluorescent dye Hoechst 33342. Eighty-four extracts from 21 plants, 12 fractions thereof and 2 purified molecules were analysed. Of these, 12 plant extracts showed synergy with ciprofloxacin, 2 of which had activity suggesting efflux inhibition. The most active extract, from Levisticum officinale, was fractionated and the two fractions displaying the greatest synergy with the five antibiotics were further analysed. From these two fractions, falcarindiol and the fatty acids oleic acid and linoleic acid were isolated. The fractions and compounds possessed antibacterial activity especially for mutants lacking a component of AcrAB-TolC. However, no synergism was seen with the fractions or purified molecules, suggesting that a combination of compounds is required for efflux inhibition. These data indicate that medicinal plant extracts may provide suitable lead compounds for future development and possible clinical utility as inhibitors of efflux for various Gram-negative bacteria.

Overexpression of patA and patB, which encode ABC transporters, is associated with fluoroquinolone resistance in clinical isolates of Streptococcus pneumoniae.

Fifty-seven clinical isolates of Streptococcus pneumoniae were divided into four groups based on their susceptibilities to the fluoroquinolones ciprofloxacin and norfloxacin and the dyes ethidium bromide and acriflavine. Comparative reverse transcription-PCR was used to determine the level of expression of the genes patA and patB, which encode putative ABC transporters. Overexpression was observed in 14 of the 15 isolates that were resistant to both fluoroquinolones and dyes and in only 3 of 24 of those resistant to fluoroquinolones only. Isolates overexpressing patA and patB accumulated significantly less of the fluorescent dye Hoechst 33342 than wild-type isolates, suggesting that PatA and PatB are involved in efflux. Inactivation of patA and patB by in vitro mariner mutagenesis conferred hypersusceptibility to ethidium bromide and acriflavine in all isolates tested and lowered the MICs of ciprofloxacin in the patAB-overproducing and/or fluoroquinolone-resistant isolates. These data represent the first observation of overexpression of patA and patB in clinical isolates and show that PatA and PatB play a clinically relevant role in fluoroquinolone resistance.

Natural and synthetic compounds such as trimethoprim behave as inhibitors of efflux in Gram-negative bacteria.

OBJECTIVES: We hypothesized that small heterocyclic or nitrogen-containing compounds could act as RND efflux pump inhibitors (EPIs). To ascertain possible EPIs, we sought to identify compounds that synergized with substrates of RND efflux pumps for wild-type bacteria and those that overexpress an efflux pump, but had no synergistic activity against strains in which a gene encoding a component of the AcrAB-TolC efflux pump had been inactivated. METHODS: Twenty-six compounds plus L-phenylalanyl-L-arginyl-beta-naphthylamide (PAbetaN) and carbonyl cyanide m-chlorophenylhydrazone (CCCP) were screened by bioassay to identify compounds that synergized with ciprofloxacin for a range of Enterobacteriaceae and Pseudomonas aeruginosa. The MICs of ciprofloxacin, tetracycline, chloramphenicol, erythromycin and ethidium bromide+/-synergizing compounds were determined, and the ability to inhibit the efflux of Hoechst 33342 was measured. RESULTS: Two compounds, trimethoprim and epinephrine, consistently showed synergy with antibiotics for most strains. The combinations did not show synergy for Salmonella enterica serovar Typhimurium in which the AcrAB-TolC efflux pump was inactive. Both compounds inhibited the efflux of Hoechst 33342. CONCLUSIONS: Two compounds, trimethoprim and epinephrine, which are already licensed for use in man, may warrant further analysis as EPIs. The combination of trimethoprim with another antibiotic is a well-used combination in anti-infective chemotherapy, and so combination with another agent, such as a quinolone, may be a viable option and further studies are now required.

Exposure of Escherichia coli and Salmonella enterica serovar Typhimurium to triclosan induces a species-specific response, including drug detoxification.

OBJECTIVES: The use of triclosan within various environments has been linked to the development of multiple drug resistance (MDR) through the increased expression of efflux pumps such as AcrAB-TolC. In this work, we investigate the effect of triclosan exposure in order to ascertain the response of two species to the presence of this widely used biocide. METHODS: The transcriptomes of Salmonella enterica serovar Typhimurium SL1344 and Escherichia coli K-12 MG1655 after exposure to the MIC of triclosan (0.12 mg/L) were determined in microarray experiments. Phenotypic validation of the transcriptomic data included RT-PCR, ability to form a biofilm and motility assays. RESULTS: Despite important differences in the triclosan-dependent transcriptomes of the two species, increased expression of efflux pump component genes was seen in both. Increased expression of soxS was observed in Salmonella Typhimurium, however, within E. coli, decreased expression was seen. Expression of fabBAGI in Salmonella Typhimurium was decreased, whereas in E. coli expression of fabABFH was increased. Increased expression of ompR and genes within this regulon (e.g. ompC, csgD and ssrA) was seen in the transcriptome of Salmonella Typhimurium. An unexpected response of E. coli was the differential expression of genes within operons involved in iron homeostasis; these included fhu, fep and ent. CONCLUSIONS: These data indicate that whilst a core response to triclosan exposure exists, the differential transcriptome of each species was different. This suggests that E. coli K-12 should not be considered the paradigm for the Enterobacteriaceae when exploring the effects of antimicrobial agents.