Epidemiological investigation of Pseudomonas aeruginosa isolates from a six-year-long hospital outbreak using high-throughput whole genome sequencing.

Although previous bacterial typing methods have been informative about potential relatedness of isolates collected during outbreaks, next-generation sequencing has emerged as a powerful tool to not only look at similarity between isolates, but also put differences into biological context. In this study, we have investigated the whole genome sequence of five Pseudomonas aeruginosa isolates collected during a persistent six-year outbreak at Nottingham University Hospitals National Health Service (NHS) Trust ­ City Campus, United Kingdom. Sequencing, using both Roche 454 and Illumina, reveals that most of these isolates are closely related. Some regions of difference are noted between this cluster of isolates and previously published genome sequences. These include regions containing prophages and prophage remnants such as the serotype-converting bacteriophage D3 and the cytotoxin-converting phage phi CTX. Additionally, single nucleotide polymorphisms (SNPs) between the genomic sequence data reveal key single base differences that have accumulated during the course of this outbreak, giving insight into the evolution of the outbreak strain. Differentiating SNPs were found within a wide variety of genes, including lasR, nrdG, tadZ, and algB. These have been generated at a rate estimated to be one SNP every four to five months. In conclusion, we demonstrate that the single base resolution of whole genome sequencing is a powerful tool in analysis of outbreak isolates that can not only show strain similarity, but also evolution over time and potential adaptation through gene sequence changes.

Activity of a dry mist hydrogen peroxide system against environmental Clostridium difficile contamination in elderly care wards.

Clostridium difficile causes serious healthcare-associated infections. Infection control is difficult, due in part to environmental contamination with C. difficile spores. These spores are relatively resistant to cleaning and disinfection. The activity of a dry mist hydrogen peroxide decontamination system (Sterinis) against environmental C. difficile contamination was assessed in three elderly care wards. Initial sampling for C. difficile was performed in 16 rooms across a variety of wards and specialties, using Brazier's CCEY (cycloserine-cefoxitin-egg yolk) agar. Ten rooms for elderly patients (eight isolation and two sluice rooms) were then resampled following dry mist hydrogen peroxide decontamination. Representative isolates of C. difficile were typed by polymerase chain reaction ribotyping. C. difficile was recovered from 3%, 11% and 26% of samples from low, medium and high risk rooms, respectively. In 10 high risk elderly care rooms, 24% (48/203) of samples were positive for C. difficile, with a mean of 6.8 colony-forming units (cfu) per 10 samples prior to hydrogen peroxide decontamination. Ribotyping identified the presence of the three main UK epidemic strains (ribotypes 001, 027 and 106) and four rooms contained mixed strains. After a single cycle of hydrogen peroxide decontamination, only 3% (7/203) of samples were positive (P<0.001), with a mean of 0.4 cfu per 10 samples ( approximately 94% reduction). The Sterinis hydrogen peroxide system significantly reduced the extent of environmental contamination with C. difficile in these elderly care rooms. This relatively quick and user-friendly technology might be a more reliable method of terminally disinfecting isolation rooms, following detergent cleaning, compared to the manual application of other disinfectants.

Primary hip and knee arthroplasty in a temporary operating theatre is associated with a significant increase in deep periprosthetic infection.

AIMS: Infection following total hip or knee arthroplasty is a serious complication. We noted an increase in post-operative infection in cases carried out in temporary operating theatres. We therefore compared those cases performed in standard and temporary operating theatres and examined the deep periprosthetic infection rates. PATIENTS AND METHODS: A total of 1223 primary hip and knee arthroplasties were performed between August 2012 and June 2013. A total of 539 (44%) were performed in temporary theatres. The two groups were matched for age, gender, body mass index and American Society of Anesthesiologists grade. RESULTS: The deep infection rate for standard operating theatres was 0 of 684 (0%); for temporary theatres it was eight of 539 (1.5%) (p = 0.001). CONCLUSION: Use of a temporary operating theatre for primary hip and knee arthroplasty was associated with an unacceptable increase in deep infection. We do not advocate the use of these theatres for primary joint arthroplasty. Cite this article: Bone Joint J 2017;99-B:917-20.

Reduction in MRSA environmental contamination with a portable HEPA-filtration unit.

There is renewed interest in the hospital environment as a potentially important factor for cross-infection with methicillin-resistant Staphylococcus aureus (MRSA) and other nosocomial pathogens. The aim of this study was to evaluate the effectiveness of a portable high-efficiency particulate air (HEPA)-filtration unit (IQAir Cleanroom H13, Incen AG, Goldach, Switzerland) at reducing MRSA environmental surface contamination within a clinical setting. The MRSA contamination rate on horizontal surfaces was assessed with agar settle plates in ward side-rooms of three patients who were heavy MRSA dispersers. Contamination rates were measured at different air filtration rates (60-235 m(3)/h) and compared with no air filtration using Poisson regression. Without air filtration, between 80% and 100% of settle plates were positive for MRSA, with the mean number of MRSA colony-forming units (cfu)/10-h exposure/plate ranging from 4.1 to 27.7. Air filtration at a rate of 140 m(3)/h (one patient) and 235 m(3)/h (two patients), resulted in a highly significant decrease in contamination rates compared with no air filtration (adjusted rate ratios 0.037, 0.099 and 0.248, respectively; P < 0.001 for each). A strong association was demonstrated between the rate of air filtration and the mean number of MRSA cfu/10-h exposure/plate (P for trend < 0.001). In conclusion, this portable HEPA-filtration unit can significantly reduce MRSA environmental contamination within patient isolation rooms, and this may prove to be a useful addition to existing MRSA infection control measures.

Systematic review of outbreaks of Pneumocystis jirovecii pneumonia: evidence that P. jirovecii is a transmissible organism and the implications for healthcare infection control.

BACKGROUND: Pneumocystis jirovecii pneumonia (PCP) is an important cause of morbidity and mortality in immunocompromised patients. Several nosocomial outbreaks of PCP have been reported in human-immunodeficiency-virus-negative, immunocompromised patients. The primary route of P. jirovecii transmission has yet to be proven; however, these outbreaks of infection suggest either interhuman transmission or a common environmental source. AIM: To identify and evaluate all published clusters and outbreaks of PCP. The main objective was to compare the epidemiology of the outbreaks, with a particular focus on the evidence for different modes of transmission. METHODS: PubMed and EMBASE were searched to identify all English-language articles describing PCP outbreaks or clusters between 1980 and March 2015. Data were extracted on the outbreak setting, features of the outbreak, application of molecular typing, results of epidemiological assessment and environmental sampling. FINDINGS: Thirty outbreaks described in 29 articles were identified. Twenty-five (83%) of these outbreaks were described in patients who had undergone solid organ transplantation, primarily renal transplantation. All studies described a defined cohort of patients who shared some nosocomial facilities, including both inpatient and outpatient areas. Genotyping was undertaken in 16 (47%) studies. Cases with an identical genotype were demonstrated in all these studies. CONCLUSIONS: The findings of this review raise a number of concerns regarding the public health and infection control implications of infection with PCP. The evidence presented for nosocomial acquisition and possible person-to-person transmission of infection suggests the need for formal infection control policies.

Ebola preparedness: a personal perspective.

The outbreak of Ebola virus disease (EVD) in West Africa and the concomitant implications for healthcare services have resulted in unique and complex challenges for infection prevention and control teams (IPCTs) worldwide. A substantial weight of responsibility was placed on IPCTs to adequately protect both patients and colleagues in the face of sometimes discrepant and often rapidly evolving national and international guidance. We reflect on our local experiences and describe some of the barriers that we faced when preparing our organization for EVD.

Serological cross reaction between legionella and campylobacter in the rapid microagglutination test.

AIMS: To investigate the serological cross reaction between legionella and campylobacter using the rapid microagglutination test (RMAT). METHODS: Serum samples from 49 patients with campylobacter infection were tested for legionella antibodies using the indirect fluorescent antibody test (IFAT) and the RMAT. Serum samples that had positive RMAT titres were retested in the presence of a campylobacter immunosorbent. The specificity of the immunosorbent was evaluated with serum from patients with genuine legionella infection (legionella culture or antigen positive, or both). RESULTS: Fourteen (28%) patients with campylobacter infection had positive IFAT titres (> or = 16) and 16 (32%) patients had positive RMAT titres (> or = 8) in one or more serum samples. In addition, serum samples from 11 of 17 patients with campylobacter infection, previously shown to have positive legionella IFAT titres, were also RMAT positive. Sixteen patients had RMAT titres of > or = 32, including seven with titres of > or = 128. RMAT titres from all but one patient were significantly reduced after campylobacter absorption, but serum samples from 48 patients with legionella infection were unaffected. CONCLUSIONS: Serological cross reaction between campylobacter and legionella can occur in the legionella RMAT, as well as the IFAT. This cross reaction can be eliminated in most cases by incorporating a campylobacter immunosorbent in the RMAT.

Comparison of Candida ID medium with sabouraud-chloramphenicol agar for the isolation of yeasts from clinical haematology surveillance specimens.

Candida ID is a new chromogenic medium for the identification of yeasts from clinical specimens. C. albicans produces blue pigmentation, whereas pink pigmentation is produced by C. tropicalis, C lusitaniae, C. guilliermondii and C. kefyr; other Candida species appear white. In this study, 240 clinical samples (throat swabs and stool samples) from haematology patients were inoculated on to Candida ID and Sabouraud-chloramphenicol agar in parallel, yielding a total of 105 yeasts; the media had overall detection rates of 85.7% and 86.7% respectively. The sensitivity of Candida ID for identification of C. albicans by blue pigmentation was 52.9% at 24 h and 94.1% at 48 h. Specificity of the blue pigmentation was 100% at 48 h. Two strains of C. tropicalis were identified, one produced pink pigmentation at 72 h, the other strain did not produce any pigmentation after 5 days. Candida ID was superior in detecting mixtures of yeasts compared with Sabouraud-chloramphenicol agar. Candida ID is a suitable primary isolation medium for yeasts from clinical specimens, providing rapid direct identification of C. albicans and enhanced detection of mixtures.

Nosocomial transmission of Saccharomyces cerevisiae in bone marrow transplant patients.

Saccharomyces cerevisiae is an unusual cause of clinical infection. We describe three bone marrow transplant patients on a haematology unit who developed possible invasive disease with the organism. Two patients died and both these patients appeared to have a related strain of S. cerevisiae. Screening for S. cerevisiae from throat and stool samples revealed four further patients who were carriers. Genotyping of the invasive and carriage strains demonstrated an indistinguishable strain from patients who had been on the unit at the same time, suggesting cross-infection.

False-positive legionella titres in routine clinical serology testing detected by absorption with campylobacter: implications for the serological diagnosis of legionnaires' disease.

A simple absorption step using blocking fluid prepared from a selected campylobacter strain was introduced in parallel with routine legionella serology tests. Over 12 months, 2716 patients were tested for legionella antibodies by the Indirect Fluorescent Antibody Test of whom 58 (2.1%) had a positive titre (> or = 16) in one or more sera. Campylobacter blocking fluid significantly reduced the legionella titres in 17 of these patients (29%) including four patients with diagnostic serology results (two of whom had pneumonia) and 13 patients with non-diagnostic titres. Absorption with campylobacter however had no effect on the legionella titres in 10 patients with positive serology, in whom legionnaires' disease had been confirmed by culture of Legionella pneumophila from sputum or detection of legionella urinary antigen by ELISA. These results indicate that the serological cross-reaction between legionella and campylobacter is encountered in routine legionella serology tests. The important implications for the diagnosis of legionnaires' disease are discussed.

Antibiotic resistance and serotypes of Streptococcus pneumoniae at Birmingham Public Health Laboratory, 1989-94.

Antibiotic resistance of 1515 consecutive laboratory isolates of Streptococcus pneumoniae between 1989 and 1994 was analyzed. Overall, 39 (2.6%) isolates were resistant to penicillin, 102 (6.7%) resistant to erythromycin and 52 (3.4%) resistant to tetracycline. There was a higher proportion of penicillin resistant isolates from sterile sites compared with "non-sterile sites" (5% vs. 2.2%; P < 0.02). This same pattern occurred with erythromycin (12.5% vs. 5.6%; P < 0.001). From 1989-90 to 1993-94 the penicillin resistance rate increased from 0.8% to 8% and the erythromycin from 5.7% to 8.4%, whereas the tetracycline resistance rate fell from 3.7% to 2.8%. The increase in resistance to penicillin largely occurred in the final 12 months of this study period. One hundred and fifty isolates (9.9%) were serotyped, including isolates from sterile sites and those with penicillin resistance. The commonest serotypes of penicillin-sensitive pneumococci were 14, 19, 9 and 6. The majority of penicillin-resistant pneumococci (PRP) were of serotype 9 (64%) followed by 6, 23 and 19. Overall 95% of these isolates were of serotypes represented in the 23-valent pneumococcal polysaccharide vaccine (Pneumovax II). PRP were more likely to have resistance to erythromycin (23%) or tetracycline (23%) compared to penicillin-sensitive pneumococci (6% and 3% respectively). Most of the PRP were isolated from patients aged over 50 years including 11 isolates from blood cultures of patients with pneumonia or septicaemia. There was a possible epidemiological association between four patients with PRP but surveillance cultures of hospital contacts revealed no extra cases. These results show a worrying increase in infections due to PRP which has implications for clinical and laboratory staff in the diagnosis and treatment of serious pneumococcal infections.

Neonatal group B streptococcal disease associated with infected breast milk.

Premature triplets each developed late onset group B streptococcal disease over a period of nine weeks. The source of the organism appeared to be expressed maternal breast milk, in the absence of clinical mastitis. Asymptomatic excretion of group B streptococcus in breast milk may be an under-recognised cause of neonatal infection.

Environmental contamination and airborne microbial counts: a role for hydroxyl radical disinfection units?

Environmental contamination is thought to play a role in the spread of infection in hospitals and there has been increased interest in novel air disinfection systems in preventing infection. In this study the efficacy of a hydroxyl radical air disinfection system (Inov8 unit) in reducing the number of airborne bacteria was assessed in a clinical setting. Environmental contamination was assessed using settle plates and air samples in three settings: (1) non-clinical room; (2) non-clinical room with defined activity; and (3) single intensive care unit cubicle. A comparison of air counts and environmental contamination rates was made with the Inov8 units on and off. The Inov8 unit produced an overall reduction in both air sample and settle plate counts in each setting (P<0.001, Wilcoxon signed-rank test). There was a mean reduction in air sample counts of 26%, 39% and 55% for settings 1, 2 and 3 respectively. The corresponding reductions in settle plate counts were 35%, 62% and 54%. These results suggest that this type of novel air disinfection may have a role in improving air quality and reducing environmental contamination within clinical isolation rooms. Further work is required to assess the effect on specific pathogens, and to establish whether this will reduce the risks of patients and/or healthcare workers acquiring such pathogens from the environment.