The development of a new three-step protocol to determine the efficacy of disinfectant wipes on surfaces contaminated with Staphylococcus aureus.

We developed a three-step protocol to quantify the efficacy of disinfectant wipes, their ability to remove and prevent microbial transfer from surfaces and their overall antimicrobial activity. Meticillin-resistant (MRSA) or -susceptible (MSSA) Staphylococcus aureus (6-7 log(10)cfu) were inoculated onto stainless steel discs with or without organic load and dried. Grapefruit extract-containing test wipes and unmedicated control wipes were used. In step 1, wipes were mechanically rotated against surfaces for 10s at 60rpm, exerting a weight of 100+/-5g. Bacterial removal was assessed by transferring the steel discs to neutraliser, resuspending and counting remaining bacteria. In step 2, bacterial transfer from wipes was assessed by eight consecutive mechanical adpression transfers to agar/neutraliser plates. Step 3 was the measurement of antimicrobial activity by direct inoculation of the wipes for 10s followed by neutralisation and enumeration. Test wipes achieved a significantly higher bacterial cell removal than control wipes on all surfaces (P<0.05). The low bactericidal activity of the wipes (<1 log(10) reduction when directly inoculated) and the subsequent survival of bacteria on the wipes, however, led to repeated microbial transfer when initially high contamination levels were present. There were no differences between MRSA and MSSA in removal, transfer or antimicrobial activity. The three-step method is a useful tool for developing future guidelines to assess the ability of wipes to disinfect surfaces.

Guidelines for the control of glycopeptide-resistant enterococci in hospitals.

The increase since the mid 1980s in glycopeptide resistant enterococci (GRE) raised concerns about the limited options for antimicrobial therapy, the implications for ever-increasing numbers of immunocompromised hospitalised patients, and fuelled fears, now realised, for the transfer of glycopeptide resistance to more pathogenic bacteria, such as Staphylococcus aureus. These issues underlined the need for guidelines for the emergence and control of GRE in the hospital setting. This Hospital Infection Society (HIS) and Infection Control Nurses Association (ICNA) working party report reviews the literature relating to GRE prevention and control. It provides guidance on microbiological investigation, treatment and management, including antimicrobial prescribing and infection control measures. Evidence identified to support recommendations has been categorized. A risk assessment approach is recommended and areas for research and development identified.

Point-of-care controls for nosocomial legionellosis combined with chlorine dioxide potable water decontamination: a two-year survey at a Welsh teaching hospital.

This study reports a two-year programme of attempted eradication of Legionella colonization in the potable water supply of a 1000-bed tertiary care teaching hospital in Wales. There was a simultaneous, point-of-care, sterile-water-only policy for all intensive care units (ICU) and bone marrow and renal transplant units in order to prevent acquisition of nosocomial Legionnaires' disease. The programme was initiated following a case of nosocomial pneumonia caused by Legionella pneumophila serogroup 1-Bellingham-like genotype A on the cardiac ICU. The case occurred 14 days after mitral and aortic valve replacement surgery. Clinical and epidemiological investigations implicated aspiration of hospital potable water as the mechanism of infection. Despite interventions with chlorine dioxide costing over 25000 UK pounds per annum, Legionella has remained persistently present in significant numbers (up to 20000 colony forming units/L) and with little reduction in the number of positive sites. Two further cases of nosocomial disease occurred over the following two-year period; in one case, aspiration of tap water was implicated again, and in the other case, instillation of contaminated water into the right main bronchus via a misplaced nasogastric tube was implicated. These cases arose because of inadvertent non-compliance with the sterile-water-only policy in high-risk locations. Enhanced clinical surveillance over the same two-year period detected no other cases of nosocomial disease. This study suggests that attempts at eradication of Legionella spp. from complex water systems may not be a cost-effective measure for prevention of nosocomial infections, and to the best of our knowledge is the first study from the UK to suggest that the introduction of a sterile-water-only policy for ICUs and other high-risk units may be a more cost-effective approach.

Successful medical therapy of Rhodococcus equi pneumonia in a patient with HIV infection.

A 34-year-old HIV-infected man was successfully treated with antimicrobial therapy alone for Rhodococcus equi pneumonia and has survived longer than six months. In the current literature, only two of seven HIV-infected patients so treated have survived as long as six months. Based on our experience and the available literature, it seems reasonable to treat HIV-infected patients with R equi pneumonia who do not require surgical intervention with prolonged intravenous therapy followed by long-term oral therapy with at least two effective antibiotics. The optimal choice and duration of antibiotic therapy need to be determined.

The role of the microbiology laboratory in the investigation of child sexual abuse.

Detection of a sexually transmitted pathogen in a child is suggestive of sexual abuse. Consequently, there are very strong clinical, social and legal reasons for diagnosing sexually transmitted disease in children correctly. Carefully considered protocols should be established for all stages of the microbiological investigation. All procedures, from specimen collection to report generation, should be undertaken to the highest possible standard with appropriate documentation. For the more commonly identified sexually transmitted pathogens in the paediatric population, the gold standard of diagnosis in the microbiology laboratory remains culture in vitro because this method offers maximum specificity. Whenever possible, culture must be followed by appropriate confirmatory tests. This highly exacting approach has significant resource and organisational implications and some tests may have to be centralised. The effective provision of an appropriate service for these cases is dependent on the local laboratory collaborating closely with hospital paediatricians and other microbiology laboratories.

Pyrolysis typing of isolates from a recurrence of systemic cryptococcosis.

Cryptococcal meningitis was diagnosed in a 71-year-old male diabetic patient with underlying ischaemic heart disease, asthma and bilateral axillo-femoral vascular grafts. After treatment with fluconazole for 2 months, the patient appeared to be cured. Two years later he presented with an aneurysm of the right graft that was resected and replaced with a new graft segment. Cryptococcus neoformans var. neoformans was grown from post-operative blood cultures and samples of the excised graft. The patient was treated with fluconazole and discharged after 6 weeks. Multiple isolates from both episodes had been preserved, and these, together with isolates from other UK patients, were cultured in duplicate, blind coded and characterised by pyrolysis mass spectrometry (PMS). Duplicate culture and re-isolate sets formed tight clusters, with each patient set clearly distinct. Sets of isolates from the two episodes in this patient formed a single tight cluster and were indistinguishable by PMS. These results support the contention that C. neoformans infection can be reactivated after being dormant for a prolonged period.

An investigation of a nosocomial outbreak of Clostridium difficile by pyrolysis mass spectrometry.

Isolates from a presumptive nosocomial outbreak of Clostridium difficile infection at a large teaching hospital were typed by pyrolysis mass spectrometry (PMS) and antibiograms. One isolate, from the putative index case, was dissimilar from the outbreak strain, but 24 isolates from 16 patients were indistinguishable by both methods. The outbreak centred on two wards for the acute care of the elderly, with a few cases elsewhere. Transfer of patients appeared to be the route of transmission between wards. There was a significant fall in the incidence of cases following intervention by the Infection Control Unit. This included ward inspection, advice on antibiotic usage and advice on prevention of faecal-oral transfer, particularly by proper handwashing. Subsequent monitoring of C. difficile infection showed a background of sporadic, dissimilar isolates with occasional apparent cross-infection incidents limited to a few patients. In suspected outbreaks, patterns of antibiotic susceptibility may be useful in initial screening, before referral for more sophisticated typing. There was excellent correlation between PMS results, antibiograms and epidemiological information.

Controversies in the prevention of neurosurgical infection.

Amongst post-operative infections, those associated with neurosurgery are of particular significance in view of their proximity to, or location within, the central nervous system. Superficial surgical site infections may be complicated by osteomyelitis of the calvarium and deeper extension to the meninges and cerebral parenchyma. The prevention, diagnosis and management of infections associated with implant devices provide similar challenges to those faced in orthopaedic and cardiac surgery. Whilst some consensus exists regarding the need for antimicrobial prophylaxis in the latter two disciplines, its place in neurosurgery remains controversial. When prophylaxis is considered, choice of antimicrobial agents should take account of up-to-date local information in relation to the relevant microbial ecology in hospitals and in the community setting. The potential for spread of blood-borne virus infections and transmissible spongiform encephalopathies in relation to neurosurgery must also be considered and it should be ensured that appropriate preventive strategies are in place.

Methicillin-resistant Staphylococcus aureus septic arthritis: urgent and emergent.

A 71-year-old male rheumatoid patient presented with MRSA septic arthritis. The impact of this organism on musculoskeletal practice is discussed.

Wound infection: MRSA.

The proportion of Staphylococcus aureus that is methicillin resistant (MRSA) has been rising in UK hospitals over the past 10 years. In some individual hospitals this increase has been explosive. The propensity for MRSA to spread arises mainly from the following reasons: Antimicrobial selection increases the biomass of MRSA in a particular patient or patient population The organism is located on exposed body surfaces(for example, the skin and nasal mucosa) MRSA is easily transferred from patient to patient, for example via the hands of staff.

Summertime Bacillus cereus colonization of hospital newborns traced to contaminated, laundered linen.

BACKGROUND: Routine screening of premature newborns for haemolytic streptococci, Staphylococcus aureus and enteric Gram-negative bacteria done at birth using umbilical swabs identified clustering of babies colonized with Bacillus cereus in summers of 2009 and 2010 at a 400-bedded UK general hospital. AIM: To determine the source of this organism by focusing on the clinical environment. METHODS: Umbilical swab screening was extended to all newborns and the labour ward environment, including construction-related dust, was sampled for B. cereus. FINDINGS: During the summer of 2009, 65% of newborns had umbilical swabs which were culture positive for B. cereus. Blood agar and B. cereus selective agar impression plates of unused labour ward linen, and freshly received linen from the hospital's external laundry, gave mainly confluent growth of B. cereus in >85% of items sampled. In-use and exposed healthcare products including liquid handwashing agents, paper hand-towels, vaginal lubricants, labour ward dust and air were culture negative. Linen contamination and umbilical swab culture positivity both approached zero in autumn. B. cereus colonization of newborn umbilici recurred in summer 2010 and unused laundered linen was again found to be as contaminated. Washing linen at the laundry in a washer-extractor, with higher dilution than the continuous tunnel washer normally used, coincided with lowering of detectable B. cereus numbers in unused washed linen and no clustering in newborns the following summer (2011). CONCLUSION: Freshly laundered linen can be contaminated with B. cereus with subsequent spread and colonization of newborns. This contamination appears to be associated with low-dilution washing and high ambient temperatures.

Evaluation of the bactericidal efficacy of three different alcohol hand rubs against clinical isolates of Staphylococcus aureus using an ex vivo carrier test.

We tested the efficacy of three alcohol hand rubs (AHRs) against Staphylococcus aureus using an ex vivo carrier test method and investigated the residual activity of AHRs and the effect of mechanical rubbing. A much longer contact time was required for the AHRs to achieve a bactericidal effect using the ex vivo test (between 10 and >20 min) compared with the in vitro test. Mechanical rubbing was found to increase the efficacy of the AHR compared to a rubbing control. Since the AHRs had no residual activity, the bactericidal effect achieved using the ex vivo test with contact times greater than the evaporation times (15 s) is unlikely to be achieved in practice. In view of such findings it is unlikely that AHRs are able to achieve a significant bactericidal effect (≥4 log(10) reduction) in practice, suggesting that contamination on the hands of healthcare workers (HCWs) may not be reduced enough to overcome the risk of cross-contamination and healthcare-associated infection. Since the AHRs had no residual effect they would be unable to prevent recolonisation of the hands of HCWs.

Survey of meticillin-resistant Staphylococcus aureus policies in UK eye departments.

The purpose of this study was to investigate meticillin-resistant Staphylococcus aureus (MRSA) screening and decolonisation practices for patients undergoing routine cataract surgery in ophthalmology departments across the UK. A postal questionnaire survey of all ophthalmology departments in the UK was carried out, with 75 of 152 (49.3%) questionnaires returned. Sixty-three percent of units had a departmental MRSA policy. Preoperative MRSA screening was performed in 50 (66.7%) units, three of which screened all preoperative patients and the remainder performed selective screening. The proportion of patients screened for MRSA ranged from 0 to 100%, with a median of 2% and a mean of 9.9% (95% confidence interval: 3.5-16.2%). Overall, 65.3% of respondents felt that their departmental policy was reasonable, although there was considerable dissatisfaction and confusion, with comments identifying lack of evidence and the need for guidelines applicable to day-case cataract surgery. The survey demonstrates significant inconsistencies in preoperative MRSA screening practice in ophthalmology departments throughout the UK. Current recommendations from the Department of Health suggest that day-case ophthalmology patients do not require routine screening, although the implication appears that high risk patients continue to do so. Further investigation is required to ascertain the scientific validity of these recommendations.

Evaluation of the bactericidal efficacy of three different alcohol hand rubs against 57 clinical isolates of S. aureus.

We tested the efficacy of three alcohol hand rubs (AHRs) used in two local Welsh intensive therapy units (ITUs) against Staphylococcus aureus. The test protocol was based on a carrier test and parameters (concentration, contact time) were chosen following observation of hand-sanitising practices in the ITUs. Following AHR exposure, surviving bacteria were enumerated using a standard plate count method plus a Bioscreen C Microbial Growth Analyser. The AHRs demonstrated variable efficacy against the clinical isolates: the mean log(10) reduction after 10 s exposure to Soft Care Med H5, Cutan and Guest Medical AHRs was 2.67, 0.696 and 1.96, respectively, and after 30 s exposure was 4.58, 1.74 and 3.60, respectively. Since the average time taken by healthcare workers (HCWs) to rub AHR onto their hands was 11 s and 15 s at the two hospitals, the efficacy of these AHRs may be significantly limited against the S. aureus isolates under the conditions observed in practice. In addition, differences observed in log(10) reduction in bacterial number post-exposure using the Bioscreen compared to the plate count method provided evidence that S. aureus may be able to recover following Guest Medical AHR treatment within 2 min exposure, whereas after 5 min exposure bacterial damage caused by the AHR was irreversible. Although the introduction of AHRs improved hand hygiene compliance among HCWs, our observations highlighted that contact time is an important factor to ensure the efficacy of these products.

Detection of cervical Chlamydia trachomatis and Neisseria gonorrhoeae with deoxyribonucleic acid probe assays in obstetric patients.

OBJECTIVE: The Gen-Probe PACE 2 deoxyribonucleic acid probe assays for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae are targeted against the ribosomal ribonucleic acid of each pathogen. Our study compared the performance of the probe assays with culture for Chlamydia trachomatis (246 patients) and Neisseria gonorrhoeae (310 patients) while screening obstetric patients. STUDY DESIGN: Using culture as a gold standard, we assessed the sensitivity, specificity, positive predictive value, and negative predictive value of the chlamydia and gonorrhea probes. RESULTS: The prevalence of chlamydia by culture was 13.4% and gonorrhea 4.8%. Against culture, the chlamydia probe assay performed as follows: sensitivity 93.9%, specificity 99.1%, positive predictive value 93.9%, and negative predictive value 99.1%. Values for the gonorrhea probe assay were 93.3%, 99.0%, 82.4%, and 99.7%, respectively. Additional molecular analysis of probe-positive-culture-negative specimens suggests that the gonorrhea probe-positive predictive value may be even higher. CONCLUSION: The Gen-Probe PACE 2 deoxyribonucleic acid probe assays for chlamydia and gonorrhea appear to be promising as convenient, reliable, and cost-effective alternatives to conventional cultures in screening obstetric patients.

Clinical significance of the emergence of bacterial resistance in the hospital environment.

Antibiotic resistance is an increasing threat in hospitals and both morbidity and mortality from infections are greater when caused by drug-resistant organisms. Whilst hospitals are universally blamed for this increase, there is an insufficient appreciation of external sources of resistance, such as when patients are admitted to hospitals from long-term care facilities in the community. The use of antibiotics in family practice and animal husbandry has also been linked to drug resistance being encountered in the hospital setting. Justifiable hospital antibiotic use, which can be life saving, may lead to 'collateral damage' with the emergence of resistance in non-target bacteria in the bowel, for example, with subsequent spread by cross-infection. At a management level, antibiotic resistance can have a significant impact on the ability of hospitals to maintain services since cohorting of patients and ward closures from outbreaks add to continuing bed shortages and waiting lists. Hospital laboratories must review their standard operating procedures since some resistance mechanisms may be missed by current methods of antibiotic susceptibility testing. With increasing public concern from press reports of 'multiresistant Staphylococcus aureus killer virus' and other drug-resistant organisms, there will inevitably be a push by national authorities for more surveillance data on antibiotic resistance; however, the cost-effectiveness of different surveillance strategies should be considered. Clinical governance and risk management are dominant themes in the National Health Service and hospital hygiene and antibiotic resistance are likely to feature prominently in audits related to these themes in the near future.