Assessing the biological efficacy and rate of recontamination following hydrogen peroxide vapour decontamination

The inanimate hospital environment can become contaminated with nosocomial pathogens. Hydrogen peroxide vapour (HPV) decontamination has proven effective for the eradication of persistent environmental contamination. We investigated the extent of meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and gentamicin-resistant Gram-negative rod (GNR) contamination in a ward side-room occupied by a patient with a history of MRSA, VRE and GNR infection and colonisation and investigated the impact of HPV decontamination. Fifteen standardised sites in the room were sampled using a selective broth enrichment protocol to culture MRSA, VRE and GNR. Sampling was performed before cleaning, after cleaning, after HPV decontamination and at intervals over the subsequent 19 days on two separate occasions. Environmental contamination was identified before cleaning on 60, 30 and 6.7% of sites for MRSA, GNR and VRE, respectively, and 40, 10 and 6.7% of sites after cleaning. Only one site (3.3%) was contaminated with MRSA after HPV decontamination. No recontamination with VRE was identified and no recontamination with MRSA and GNR was identified during the two days following HPV decontamination. Substantial recontamination was identified approximately one week after HPV decontamination towards post-cleaning levels for GNR and towards pre-cleaning levels for MRSA. HPV is more effective than standard terminal cleaning for the eradication of nosocomial pathogens. Recontamination was not immediate for MRSA and GNR but contamination returned within a week in a room occupied by a patient colonised with MRSA and GNR. This finding has important implications for the optimal deployment of HPV decontamination in hospitals.     

Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination

The hospital environment can sometimes harbour methicillin-resistant Staphylococcus aureus (MRSA) but is not generally regarded as a major source of MRSA infection. We conducted a prospective study in surgical wards of a London teaching hospital affected by MRSA, and compared the effectiveness of standard cleaning with a new method of hydrogen peroxide vapour decontamination. MRSA contamination, measured by surface swabbing was compared before and after terminal cleaning that complied with UK national standards, or hydrogen peroxide vapour decontamination. All isolation rooms, ward bays and bathrooms tested were contaminated with MRSA and several antibiogram types were identified. MRSA was common in sites that might transfer organisms to the hands of staff and was isolated from areas and bed frames used by non-MRSA patients. Seventy-four percent of 359 swabs taken before cleaning yielded MRSA, 70% by direct plating. After cleaning, all areas remained contaminated, with 66% of 124 swabs yielding MRSA, 74% by direct plating. In contrast, after exposing six rooms to hydrogen peroxide vapour, only one of 85 (1.2%) swabs yielded MRSA, by enrichment culture only. The hospital environment can become extensively contaminated with MRSA that is not eliminated by standard cleaning methods. In contrast, hydrogen peroxide vapour decontamination is a highly effective method of eradicating MRSA from rooms, furniture and equipment. Further work is needed to determine the importance of environmental contamination with MRSA and the effect on hospital infection rates of effective decontamination.     

A study of the relationship between environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) and patients' acquisition of MRSA.

OBJECTIVE: The study aimed to examine the presence of methicillin-resistant Staphylococcus aureus (MRSA) in the environment and its relationship to patients' acquisition of MRSA. DESIGN: A prospective study was conducted in a 9-bed intensive care unit for 14 months. At every environmental screening, samples were obtained from the same 4 sites in each bed space. Patients were screened at admission and then 3 times weekly. All environmental and patient strains were typed using pulsed-field gel electrophoresis. RESULTS: MRSA was isolated from the environment at every environmental screening, when both small and large numbers of patients were colonized. Detailed epidemiological typing of 250 environmental and 139 patient isolates revealed 14 different pulsed-field gel electrophoresis profiles, with variants of EMRSA-15 being the predominant type. On only 20 (35.7%) of 56 occasions were the strains isolated from the patients and the strains isolated from their immediate environment indistinguishable. There was strong evidence to suggest that 3 of 26 patients who acquired MRSA while in the intensive care unit acquired MRSA from the environment. CONCLUSIONS: This study reveals widespread contamination of the hospital environment with MRSA, highlights the complexities of the problem of contamination, and confirms the need for more-effective cleaning of the hospital environment to eliminate MRSA.     

Environmental contamination makes an important contribution to hospital infection

Meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are capable of surviving for days to weeks on environmental surfaces in healthcare facilities. Environmental surfaces frequently touched by healthcare workers are commonly contaminated in the rooms of patients colonized or infected with MRSA or VRE. A number of studies have documented that healthcare workers may contaminate their hands or gloves by touching contaminated environmental surfaces, and that hands or gloves become contaminated with numbers of organisms that are likely to result in transmission to patients. Pathogens may also be transferred directly from contaminated surfaces to susceptible patients. There is an increasing body of evidence that cleaning or disinfection of the environment can reduce transmission of healthcare-associated pathogens. Because routine cleaning of equipment items and other high-touch surfaces does not always remove pathogens from contaminated surfaces, improved methods of disinfecting the hospital environment are needed. Preliminary studies suggest that hydrogen peroxide vapour technology deserves further evaluation as a method for decontamination of the environment in healthcare settings.     

Environmental reservoirs of methicillin-resistant Staphylococcus aureus in isolation rooms: correlation with patient isolates and implications for hospital hygiene

Strategies to control and prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA) include early identification of positive patients through screening, patient isolation, hand hygiene, nasal and skin decontamination, and the adequate cleaning and decontamination of clinical areas. However, many national and other guidelines provide few details on environmental decontamination regimens, partly because the role of the environment in the spread of MRSA is not well documented. We prospectively studied the environment of the isolation rooms of 25 MRSA patients for up to four weeks, sampling horizontal surfaces and the air using settle plates as well as an air sampler, while continuing regular daily cleaning according to the hospital protocol. We then typed 20 patient isolates and the corresponding environmental isolates (N=35) to assess the similarity of strains. A high proportion of samples were positive for MRSA; 269/502 (53.6%) surface samples, 70/250 (28%) air samples and 102/251 (40.6%) settle plates. Over half of the surface samples taken from the beds and the mattresses were positive for MRSA. Identical or closely related isolates were recovered from the patient and their environment in 14 (70%) patients, suggesting possible environmental contamination of the isolation rooms, possibly contributing to endemic MRSA. More effective and rigorous use of current approaches to cleaning and decontamination is required as well as consideration of newer technologies to eradicate MRSA and other hospital-acquired pathogens.     

A purpose built MRSA cohort unit

The control of hospital-acquired infection, in particular methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge. Our hospital has established a purpose built 11-bed cohort unit with on-site rehabilitation for care of patients colonized with MRSA, in an attempt to improve their quality of care. Prior to the opening of this unit a number of concerns were voiced and the aim of this study was to address these. First, to establish if patient cohorting reduces the likelihood of successful decolonization, second, to evaluate the risk of staff colonization, and finally to see if successful environmental control of MRSA is possible.A patient database was established detailing patient demographics, infection rates, eradication and reacquisition rates. Staff screening was performed weekly, at the start of a period of duty. Sixty environmental sites were screened before unit opening, at 48h, six weeks and at six months.There were 88 admissions in the first six months; 62 patients were colonized with MRSA, and 26 patients (10 surgical, 16 medical) had MRSA infections. Twenty-three of 88 patients (26%) were successfully decolonized, which compares favourably with an eradication rate of 20% for the rest of the hospital. Twenty staff members participated in weekly screening. Five staff members colonized with MRSA were detected and all were successfully decolonized. Environmental control was achieved with a combination of a daily detergent clean and a once weekly clean with phenolic disinfectant.Our preliminary data suggest that, despite cohorting patients colonized with MRSA, with proper education and supervised cleaning protocols, it is possible to control environmental MRSA load, successfully decolonize patients and limit the risk of staff colonization.     

Risk of hand or glove contamination after contact with patients colonized with vancomycin-resistant enterococcus or the colonized patients' environment.

OBJECTIVE: To estimate the level of hand or glove contamination with vancomycin-resistant enterococci (VRE) among healthcare workers (HCWs) who touch a patient colonized with VRE and/or the colonized patient's environment during routine care. DESIGN: Structured observational study. SETTING: Medical intensive care unit of a 700-bed, tertiary-care teaching hospital. PARTICIPANTS: VRE-colonized patients and their caregivers. METHODS: We obtained samples from sites on the intact skin of 22 patients colonized with VRE and samples from sites in the patients' rooms, before and after routine care, during 27 monitoring episodes. A total of 98 unique HCWs were observed during 131 HCW observations. Observers recorded the sites touched by HCWs. Culture samples were obtained from HCWs' hands and gloves before and after care. RESULTS: VRE were isolated from a mean (+/-SD) of 55% +/- 24% of patient sites (n=256) and 17% +/- 12% of environmental sites (n=1,572). Most HCWs (131 [56%]) touched both the patient and the patient's environment; no HCW touched only the patient. Of 103 HCWs whose hand samples were negative for VRE when they entered the room, 52% contaminated their hands or gloves after touching the environment, and 70% contaminated their hands or gloves after touching the patient and the environment (P=.101). In a univariate logistic regression model, the risk of hand or glove contamination was associated with the number of contacts made (odds ratio, 1.1 [95% confidence interval, 1.01-1.19). In a multivariate model, the effect of the number of contacts could not be distinguished from the effect of type of contact (ie, touching the environment alone or touching both the patient and the environment). Overall, 37% of HCWs who did not wear gloves contaminated their hands, and 5% of HCWs who wore gloves did so (an 86% difference). CONCLUSION: HCWs were nearly as likely to have contaminated their hands or gloves after touching the environment in a room occupied by a patient colonized by VRE as after touching the colonized patient and the patient's environment. Gloves were highly protective with respect to hand contamination.     

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((R))) 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((R)) 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.     

Airborne hydrogen peroxide for disinfection of the hospital environment and infection control: a systematic review

We reviewed the effectiveness of airborne hydrogen peroxide as an environmental disinfectant and infection control measure in clinical settings. Systematic review identified ten studies as eligible for inclusion. Hydrogen peroxide was delivered in the form of vapour and dry mist in seven and three studies, respectively. Pathogens evaluated included meticillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile and multiple bacterial types, in five, three, and two studies, respectively. Before the application of any cleaning intervention, 187/480 (39.0%; range: 18.9-81.0%) of all sampled environmental sites were found to be contaminated by the studied pathogens in nine studies that reported specific relevant data. After application of terminal cleaning and airborne hydrogen peroxide, 178/630 (28.3%; range: 11.9-66.1%) of the sampled sites in six studies and 15/682 (2.2%; range: 0-4.0%) of the sampled sites in ten studies, respectively, remained contaminated. Four studies evaluated the use of hydrogen peroxide vapour for infection control. This was associated with control of a nosocomial outbreak in two studies, eradication of persistent environmental contamination with MRSA and decrease in C. difficile infection in each of the remaining two studies.     

Carriage of multiple subtypes of methicillin-resistant Staphylococcus aureus by intensive care unit patients.

OBJECTIVE: To determine how consistently patients are colonized with methicillin-resistant Staphylococcus aureus (MRSA) at various sites and how many subtypes can be carried simultaneously by a single patient. SETTING: A 28-bed Intensive care unit in a tertiary-care referral hospital. METHODS: A total of 1,181 patients were screened by culture of swab specimens obtained from the nose, throat, groin, and axilla on admission to the intensive care unit (ICU), twice weekly during their ICU stay, and at discharge. RESULTS: MRSA was isolated at least once from 224 patients. Of these isolates, 359 were selected from 32 patients to be subtyped using pulsed-field gel electrophoresis. The rate of compliance with collection of swab specimens was 79.9%. The combination of sites colonized varied frequently over time for many patients. Of patients who had swab specimens obtained twice in 1 day, 8.7% had discordant results from the 2 swab sets. No patient had a clinical isolate that was not of an identical subtype to an isolate from an anatomical site that was sampled for screening. Half the patients carried multiple subtypes during their stay, with up to 4 subtypes per patient. CONCLUSIONS: The findings of this study may indicate that these patients have been colonized with MRSA on more than one occasion, possibly because of multiple breaches in infection control procedure. In MRSA-colonized patients, anatomical sites were intermittently colonized and carriage of multiple subtypes was common. These findings indicate that MRSA carriage is not a fixed state but may vary over time.     

Widespread environmental contamination associated with patients with diarrhea and methicillin-resistant Staphylococcus aureus colonization of the gastrointestinal tract.

OBJECTIVE: Patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) may contaminate their immediate environment with this organism. However, the extent to which gastrointestinal colonization with MRSA affects environmental contamination is not known. We investigated the frequency of environmental contamination in the rooms of patients with diarrheal stools and heavy gastrointestinal colonization with MRSA. DESIGN: Prospective observational study. SETTING: A 500-bed teaching hospital. METHODS: Stool specimens submitted for Clostridium difficile toxin assays were inoculated onto colistin-naladixic acid agar. MRSA was identified with standard methods. Samples from a standardized list of 10 environmental surfaces were cultured, from the rooms of 8 patients who had diarrhea that yielded heavy growth of MRSA (case patients) and from the rooms of 6 MRSA-positive patients with stool cultures negative for MRSA (control patients). MRSA isolates from 13 patients (8 case patients and 5 control patients) and 64 of the environmental isolates recovered from their rooms were compared by pulsed-field gel electrophoresis (PFGE). One clinical isolate from a control patient was excluded because there was no corresponding environmental MRSA isolate with which to compare it. RESULTS: Overall, MRSA were recovered from 47 (58.8%) of 80 surfaces in the rooms of case patients, compared with 14 (23.3%) of 60 surfaces in the rooms of control patients (58.8% [95% CI, 47.8-68.9] vs 23.3% [95% CI, 14.3-35.5]; P<.0001). The items most commonly contaminated were bedside rails, blood pressure cuffs, television remote controls, and toilet seats. Seventy-eight percent of the environmental isolates in patients' rooms had PFGE types that were indistinguishable or closely related to those recovered from the patients' clinical specimens. CONCLUSIONS: Patients who have diarrheal stools and heavy gastrointestinal colonization with MRSA are associated with significantly greater environmental MRSA contamination than patients without MRSA in their stool, and they are likely to be the source of that contamination.     

Control of an outbreak of multidrug-resistant Acinetobacter baumannii-calcoaceticus colonization and infection in an intensive care unit (ICU) without closing the ICU or placing patients in isolation.

OBJECTIVE: To describe the control of multidrug-resistant Acinetobacter baumannii-calcoaceticus (MDRABC) colonization and infection in an intensive care unit (ICU). SETTING: An 18-bed ICU in a large tertiary care teaching hospital in London. INTERVENTIONS: After recognition of the outbreak, a range of infection control measures were introduced over several months that were primarily aimed at reducing environmental contamination with the outbreak strain. Strategies included use of a closed tracheal suction system for all patients receiving mechanical ventilation, use of nebulized colistin for patients with evidence of mild to moderate ventilator-associated pneumonia, improved availability of alcohol for hand decontamination, and clearer designation of responsibilities and strategies for cleaning equipment and the environment in the proximity of patients colonized or infected with MDRABC. RESULTS: The outbreak lasted from June 2001 through November 2002 and involved 136 new cases of MDRABC infection or colonization. The number of newly diagnosed cases per month reached a maximum of 15 in February 2002, and the number of new cases slowly decreased over the next 9 months. CONCLUSION: This outbreak was controlled by emphasizing the control of environmental reservoirs and did not require recourse to ward closure or placement of affected patients in isolation.     

Antimicrobial therapy for methicillin-resistant Staphylococcus aureus colonization in residents and staff of a Veterans Affairs nursing home care unit.

OBJECTIVE: To evaluate the effect of antimicrobial therapy on patients and staff colonized with methicillin-resistant Staphylococcus aureus (MRSA) in a skilled nursing facility and to assess the role of the environment as a potential reservoir for MRSA in the nursing home setting. DESIGN: As part of a comprehensive program to control an MRSA outbreak in a nursing home, patients and staff colonized with MRSA received 1 of 3 antimicrobial decolonization regimens depending upon the site and extent of colonization. Followup cultures were performed during therapy and on days 2, 7, 14, and 30 following the completion of therapy. Cultures of the patients' inanimate environment (pajamas, sheet, and floor) were obtained during and after therapy. Antimicrobial susceptibility tests were performed on 54 MRSA isolates obtained before and 44 MRSA isolates recovered after therapy. SETTING: A 120-bed Veterans Affairs nursing home care unit. PARTICIPANTS: Thirty-six patients and 7 staff nurses colonized with MRSA at 1 or more sites. INTERVENTION: Decolonization therapy with rifampin, trimethoprim-sulfamethoxazole, and clindamycin used alone or in various combinations for 5 or 10 days in conjunction with other infection control measures employed to combat the MRSA outbreak. RESULTS: Twenty (56%) of the 36 NHCU patients were either persistently colonized or became recolonized with MRSA during the 30-day followup period. Positive cultures on day 3 during therapy frequently identified patients who subsequently exhibited persistent or recurrent colonization. Before therapy, 92% of MRSA isolates were susceptible to rifampin, whereas only 43% of the isolates obtained after therapy were susceptible. Sixteen (80%) of 20 patients with persistent or recurrent colonization had rifampin-resistant strains of MRSA isolated after therapy. Twenty-three (18%) of 125 environmental cultures obtained during and after therapy from patients who exhibited persistent or recurrent colonization were positive for MRSA, in contrast to 9 (8%) of 107 from patients who were successfully decolonized. CONCLUSIONS: The decolonization component of the outbreak control program was judged to be ineffective and potentially hazardous because colonization persisted or recurred in more than half of the patients, and substantial antimicrobial resistance was noted in MRSA stains isolated after therapy. Resistance, especially to rifampin, and possibly re-acquisition of MRSA from other human or environmental sources were 2 factors that appeared to impede the decolonization effort.     

Outbreak of methicillin-resistant Staphylococcus aureus colonization and infection in a neonatal intensive care unit epidemiologically linked to a healthcare worker with chronic otitis.

OBJECTIVE: To describe the investigation and interventions necessary to contain an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection in a neonatal intensive care unit (NICU). DESIGN: Retrospective case finding that involved prospective performance of surveillance cultures for detection of MRSA and molecular typing of MRSA by repetitive-sequence polymerase chain reaction (rep-PCR). SETTING: Level III NICU in a tertiary care center. PARTICIPANTS: Three neonates in a NICU were identified with MRSA bloodstream infection on April 16, 2004. A point prevalence survey identified 6 additional colonized neonates (attack rate, 75% [9 of 12 neonates]). The outbreak strain was phenotypically unusual. INTERVENTIONS: Cohorting and mupirocin therapy were initiated for neonates who had acquired MRSA during the outbreak. Contact precautions were introduced in the NICU, and healthcare workers (HCWs) were retrained in cleaning and disinfection procedures and hand hygiene. Noncolonized neonates and newly admitted patients had surveillance cultures performed 3 times per week. RESULTS: Two new colonized neonates were identified 1 month later. HCW X, who had worked in the NICU since June 2003, was identified as having chronic otitis. MRSA was isolated from cultures of swab specimens from HCW X's ear canal and nares. HCW X was epidemiologically linked to the outbreak. Molecular typing (by rep-PCR) confirmed that the isolates from HCW X and from the neonates were more than 90% similar. Retrospective review of NICU isolates revealed that the outbreak strain was initially cultured from a neonate 2 months after HCW X began working on the unit. The epidemic strain was eradicated after removing HCW X from patient care in the NICU. CONCLUSION: An outbreak of MRSA colonization and infection in a NICU was epidemiologically linked to a HCW with chronic otitis externa and nasal colonization with MRSA. Eradication was not achieved until removal of HCW X from the NICU. Routine surveillance for MRSA may have allowed earlier recognition of the outbreak and is now standard practice in our NICU.     

Investigation and management of an outbreak of multidrug-carbapenem-resistant Acinetobacter baumannii in Cambridge, UK

Multidrug-resistant Acinetobacter baumannii resistant to carbapenems (MRAB-C) has become endemic in many hospitals in the UK. We describe an outbreak of MRAB-C that occurred on two intensive care units using ORION criteria (Outbreak Reports and Intervention studies Of Nosocomial infection). All patients colonised or infected with MRAB-C were included. Enhanced infection control precautions were introduced in Phase 1 of the outbreak. The adult neurosciences critical care unit (NCCU) was partially closed in Phase 2 and strict patient segregation, barrier nursing and screening thrice weekly was introduced. When control was achieved, NCCU was reopened (Phase 3) with post-discharge steam cleaning and monthly cleaning of extract and supply vents. There were 19 cases, 16 on NCCU and three on the general intensive care unit (ICU). Mean age was 52 years, with six cases being female. All patients were mechanically ventilated and ten had either an extraventricular drain or intracranial pressure monitoring device in place. Four patients developed a bacteraemia, with one further case of ventriculitis. Nine patients had no clinical evidence of infection and four were identified initially on screening. Ten patients were treated; there were eight deaths. Environmental samples showed heavy contamination throughout NCCU. MRAB-C affects critically ill patients and is associated with high mortality. This outbreak was controlled by early involvement of management, patient segregation, screening of patients and the environment, and increased hand hygiene environmental cleaning and clinical vigilance. A multidisciplinary approach to outbreak control is mandatory.     

An epidemiological survey of methicillin-resistant Staphylococcus aureus in a tertiary referral hospital

Over a 30-month period from July 1995 to December 1997, new detections of methicillin-resistant Staphylococcus aureus (MRSA) were prospectively studied in a tertiary referral hospital. The aims of the study were to determine the incidence of colonization of patients admitted to each of the hospital's 39 clinical units and ascertain where each patient had become colonized. Epidemiological information (time to detection, ward movement, admission to other hospitals, data on MRSA isolations in hospital wards) and phage typing were used by the hospital's infection control unit to make this determination. Routine containment procedures included cohorting, flagging and triclosan body washes. Surveillance cultures were collected infrequently. Patients known to be colonized with MRSA were excluded from orthopaedic and haematology wards. During the study period, 995 patients were found to be newly colonized. The incidence of colonization varied from nil to 72 per 1000 admissions, being highest in the main intensive care unit and in services which frequently used that unit. The incidence of colonization in elective orthopaedic surgery (< 1 per 1000) and haematology (3 per 1000) was very low. Determining the place where patients acquired MRSA was made difficult by the high frequency of endemic phage types and frequent patient transfer between wards. Epidemiological data suggested that the main intensive care unit and surgical wards nursing patients with colorectal, urological and vascular diseases were the places where most patients became colonized. MRSA was never acquired by patients nursed in wards which practised an exclusion policy towards patients known to be colonized with MRSA. Our data suggest that in tertiary referral hospitals, where MRSA is not only endemic but frequently imported from other hospitals, it is possible to establish areas where MRSA is never acquired.     

环境筛查系列措施对ICU物体表面多重耐药菌检出率的影响

目的 探讨多重耐药菌环境筛查对降低重症监护病房(ICU)物体表面耐甲氧西林金黄色葡萄球菌(MRSA)和耐碳青霉烯类鲍曼不动杆菌(CRAB)的效果.方法 2018年9—11月为基线调查期;2018年12月—2019年8月为干预期,干预期每季度进行常规筛查,及时反馈,加强环境清洁消毒及相关知识培训;比较干预前后环境物体表面...     

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.     

An outbreak of multiply-resistant Klebsiella pneumoniae in the Grampian region of Scotland

A predominantly hospital-based outbreak of multiply-resistant Klebsiella pneumoniae capsular type K₂ (MRK) expressing expanded spectrum β-lactamase (ESBL) activity and fully sensitive only to the carbapenems and amikacin is described. The organism was isolated from 283 patients between March 1992 and September 1995. The outbreak started in the intensive care unit (ICU) of a major acute hospital and spread through surgical wards, a medical ward, a geriatric unit in a separate hospital and various other local hospitals. Environmental screening revealed extensive ward contamination. The decline of the outbreak after the spring of 1995 coincided with the re-emphasis of standard infection control procedures and the launch of a works programme aimed at addressing underlying sites of environmental contamination. Of the 283 cases, 166 (59·0%) were detected through a specially instigated case finding programme. The MRK caused 11 cases of septicaemia, two postoperative intra-abdominal abscesses, one case of postoperative meningitis, 102 cases of urinary tract infection and 28 wound infections and was isolated from the respiratory tracts of five patients with ventilator associated pneumonia. The difficulty in controlling the outbreak is ascribed to heavy environmental contamination, frequent inter- and infra-hospital patient transfers and prolonged carriage of the outbreak strain.