Distribution of multi-resistant Gram-negative versus Gram-positive bacteria in the hospital inanimate environment

We prospectively studied the difference in detection rates of multi-resistant Gram-positive and multi-resistant Gram-negative bacteria in the inanimate environment of patients harbouring these organisms. Up to 20 different locations around 190 patients were surveyed. Fifty-four patients were infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) and 136 with multi-resistant Gram-negative bacteria. The environmental detection rate for MRSA or VRE was 24.7% (174/705 samples) compared with 4.9% (89/1827 samples) for multi-resistant Gram-negative bacteria (P<0.001). Gram-positive bacteria were isolated more frequently than Gram-negatives from the hands of patients (P<0.001) and hospital personnel (P=0.1145). Environmental contamination did not differ between the intensive care units (ICUs) and the general wards (GWs), which is noteworthy because our ICUs are routinely disinfected twice a day, whereas GWs are cleaned just once a day with detergent. Current guidelines for the prevention of spread of multi-resistant bacteria in the hospital setting do not distinguish between Gram-positive and Gram-negative isolates. Our results suggest that the inanimate environment serves as a secondary source for MRSA and VRE, but less so for Gram-negative bacteria. Thus, strict contact isolation in a single room with complete barrier precautions is recommended for MRSA or VRE; however, for multi-resistant Gram-negative bacteria, contact isolation with barrier precautions for close contact but without a single room seems sufficient. This benefits not only the patients, but also the hospital by removing some of the strain placed on already over-stretched resources.     

Control of vancomycin-resistant enterococci at a community hospital: efficacy of patient and staff cohorting.

OBJECTIVE: To evaluate the efficacy of patient and staff cohorting to control vancomycin-resistant enterococci (VRE) at an Indianapolis community hospital. DESIGN: To interrupt transmission of VRE, a VRE point-prevalence survey of hospital inpatients was conducted, and VRE-infected or -colonized patients were cohorted on a single ward with dedicated nursing staff and patient-care equipment. To assess the impact of the intervention, staff compliance with contact isolation procedures was observed, and the VRE point-prevalence survey was repeated 2 months after the cohort ward was established. RESULTS: Following the establishment of the cohort ward, VRE prevalence among all hospitalized inpatients decreased from 8.1% to 4.7% (25 positive cultures among 310 patients compared to 13 positive cultures among 276 patients, P=.14); VRE prevalence among patients whose VRE status was unknown before cultures were obtained decreased from 5.9% to 0.8% (18 positive cultures among 303 patients compared to 2 positive cultures among 262 patients, P=.002); and observed staff-patient interactions compliant with published isolation recommendations increased (5 [22%] of 23 interactions compared to 36 [88%] of 41 interactions, P<.0001). CONCLUSIONS: Our data suggest that, in hospitals with endemic VRE or continued VRE transmission despite implementation of contact isolation measures, establishing a VRE cohort ward may be a practical and effective method to improve compliance with infection control measures and thereby to control epidemic or endemic VRE transmission.     

Efficacy of infection control strategies to reduce transmission of vancomycin-resistant enterococci in a tertiary care hospital in Korea: a 4-year follow-up study.

To determine the effectiveness of infection control strategies to reduce transmission of vancomycin-resistant enterococci (VRE), a cohort study was performed in a university hospital. Contact precautions alone were not effective in reducing transmission of VRE. Strict isolation of affected patients in private rooms, in addition to use of contact precautions, showed a significantly improved reduction in the transmission of VRE.     

An outbreak of vancomycin-resistant enterococci in a hematology-oncology unit: control by patient cohorting and terminal cleaning of the environment.

We describe the impact of enhanced infection control interventions on controlling the spread of vancomycin-resistant enterococci (VRE) in our hematology-oncology unit. Between April and September 1998, 13 patients on this unit were identified as having VRE. In addition to contact precautions, other measures that were needed to control the outbreak included closure of the unit to new admissions, creation of a cohort of VRE-positive patients and staff, and thorough cleaning of patients' rooms with 0.5% sodium hypochlorite.     

The relationship of a clonal outbreak of Enterococcus faecium vanA to methicillin-resistant Staphylococcus aureus incidence in an Australian hospital

Australian isolates of vancomycin-resistant enterococci (VRE) have been widely scattered geographically, predominantly polyclonal and of the VanB phenotype. Forty-nine VRE were isolated from 47 patients in our hospital from October 1996 to December 1999. Forty-four of these VRE were Enterococcus faecium with a vanA glycopeptide resistance genotype. Four isolates were pathogenic. Thirty-five VRE were from an outbreak in the Renal and Infectious Diseases Units over a four-month period. Pulsed-field gel electrophoresis (PFGE) demonstrated that 41 of the 49 VRE were indistinguishable or closely related. Enhanced environmental cleaning, strict contact isolation of colonized patients and reducing inpatient admissions terminated the epidemic. Cohorting of methicillin-resistant Staphylococcus aureus (MRSA)-positive patients was restricted because VRE patients occupied the isolation facilities. This resulted in a statistically significant increase in MRSA infections across the hospital. VRE epidemics have the ability to influence the epidemiology of other nosocomial pathogens when infection control resources are exhausted.     

A hospital epidemic of vancomycin-resistant Enterococcus: risk factors and control.

OBJECTIVE: To determine risk factors for vancomycin-resistant Enterococcus (VRE) colonization during a hospital outbreak and to evaluate Centers for Disease Control and Prevention (CDC)-recommended control measures. DESIGN: Epidemiological study involving prospective identification of colonization and a case-control study. SETTING: A university hospital. PARTICIPANTS: Patients on eight wards involved in outbreak from late 1994 through early 1995. METHODS: Cases were matched by ward and culture date with up to two controls. Risk factors were evaluated with four multivariate models using conditional logistic regression. The first evaluated proximity to other VRE patients and isolation status. The second evaluated proximity to unisolated VRE cases and three variables independently predictive after adjustment for proximity. The third evaluated seven significant univariate predictors in addition to proximity to unisolated VRE in backward, stepwise logistic regression. The fourth assessed proximity to VRE with all other variables collected, clustered in a principal components analysis. Pulsed-field gel electrophoresis was performed to assess clonality of two outbreak strains. RESULTS: The incidence of transmission declined significantly after CDC guidelines were implemented. Proximity to unisolated VRE cases during the prior week was a significant predictor of acquisition in each of four multivariate models. Other significant risk factors in multivariate models included a history of major trauma and treatment with metronidazole. Pulsed-field gel electrophoresis confirmed the clonality of two outbreak strains. CONCLUSIONS: VRE was transmitted between patients during a hospital epidemic, with proximity to previously unisolated VRE patients being an important risk factor. Weekly surveillance cultures and contact isolation of colonized patients significantly reduced spread     

Nosocomial outbreak of vancomycin-resistant Enterococcus faecium at a German university pediatric hospital

Nosocomial Infections caused by vancomycin-resistant enterococci (VRE) are an emerging threat to critically ill patients. At the University Hospital Eppendorf, VRE were isolated from 38 patients between August 1993 and April 1997, of whom 32 were hospitalized at the Department of Pediatrics. Pulsed-field gel electrophoresis revealed that 26 Enterococcus faecium isolates from patients of the Department of Pediatrics were identical or closely related, and that isolates from three additional patients of the same department were possibly related. All of these isolates were of vanA genotype. They were resistant to glycopeptides, ampicillin, ciprofloxacin, clindamycin, and erythromycin. Most isolates displayed high-level resistance to gentamicin, but all remained susceptible to quinupristin/dalfopristin. Implementation of stringent hand disinfection and environmental disinfection policies, as well as measures for patient isolation contained this first outbreak of VRE at a German Children's hospital, which emphasizes the importance of hygienic measures for the control of nosocomial spread of these organisms.     

Elimination of epidemic methicillin-resistant Staphylococcus aureus from a university hospital and district institutions,Finland

From August 1991 to October 1992, two successive outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) occurred at a hospital in Finland. During and after these outbreaks, MRSA was diagnosed in 202 persons in our medical district; >100 cases involved epidemic MRSA. When control policies failed to stop the epidemic, more aggressive measures were taken, including continuous staff education, contact isolation for MRSA-positive patients, systematic screening for persons exposed to MRSA, cohort nursing of MRSA-positive and MRSA-exposed patients in epidemic situations, and perception of the 30 medical institutions in that district as one epidemiologic entity brought under surveillance and control of the infection control team of Turku University Hospital. Two major epidemic strains, as well as eight additional strains, were eliminated; we were also able to prevent nosocomial spread of other MRSA strains. Our data show that controlling MRSA is possible if strict measures are taken before the organism becomes endemic. Similar control policies may be successful for dealing with new strains of multiresistant bacteria, such as vancomycin-resistant strains of S. aureus.     

Rapid control of an outbreak of vancomycin-resistant enterococci in a French university hospital

Vancomycin-resistant enterococci (VRE) are emerging in French hospitals. A VRE outbreak occurred in our hospital, prompting efforts to eradicate the organism. The following interventions were implemented simultaneously to control the outbreak: (1) creation of a VRE control committee; (2) cohorting of VRE carriers in a dedicated ward; (3) extensive screening of contact patients; (4) use of a sensitive technique for detecting VRE in rectal samples; (5) intervention of a dedicated team to reduce consumption of selected antibiotics; (6) information for, and education of, all hospital staff; and (7) electronic tracking of in-hospital transfer and readmission of VRE carriers and contact patients. Over a four-week period following admission of the index case, 37 carriers of a single strain of vanA vancomycin-resistant Enterococcus faecium were identified across seven units. A single additional readmitted contact patient was identified later. Of the 39 VRE-positive patients, two had urinary tract infections and 37 were colonised. Of the 32 patients with known VRE stool concentrations, 23 had low and nine high concentrations. One low-concentration patient precipitated transmission in another unit. This aggressive, co-ordinated, multifaceted strategy was successful in halting a widespread VRE outbreak in our hospital.     

Discrimination between epidemic and non-epidemic glycopeptide-resistant E. faecium in a post-outbreak situation

Vancomycin-resistant enterococci (VRE) have been isolated in increasing numbers. Hospital-adapted VRE exhibit relatively high pathogenicity by expressing factors like enterococcal surface protein (Esp), which facilitates epidemic spread. By contrast, 'community-acquired' VRE show low pathogenicity and non-epidemic features. In 2004 and 2005 an extended outbreak of VRE occurred at a university hospital in Southwestern Germany and an infection control programme was implemented to confine the outbreak. Pulsed-field gel electrophoresis (PFGE), esp PCR, multiple-locus variable number of tandem repeat analysis (MLVA), purK1 typing and multiple-locus sequence typing (MLST) were performed on representative VRE isolates. Twenty-six non-epidemic and two epidemic VRE types (MLST203, MLST280) were identified by PFGE. Seven of the non-outbreak VRE types were esp gene negative, whereas 19 non-outbreak and both epidemic VRE types were esp positive. Eight MLVA types were identified. MLVA type 1 included five PFGE types and MLVA type 159 included 16 PFGE types. Currently there is no efficient method available to identify non-epidemic VRE and avoid unnecessary isolation of patients. More than 50% non-epidemic clones were esp positive; nevertheless, esp PCR appears to be the most promising approach to identify non-epidemic VRE.     

Epidemiologic increase of various genotypes of vancomycin-resistant Enterococcus faecium in a university hospital

After a report of a possible relationship between an outbreak of vancomycin-resistant enterococci (VRE) in a nearby hospital and earlier admission of two of the patients with this VRE in the University Medical Centre of Utrecht (UMCU), the Netherlands, an extensive search for VRE carriers was started in the UMCU. In the study period of two months, VRE carriership was diagnosed in 51 patients in nine of the 11 wards investigated. Twenty-six patients in eight wards were colonized with the same VRE genotype as in the nearby hospital; spread was demonstrated in three wards. In addition, six patients of one ward were colonized with a second genotype and seven other patients with a third genotype, while 12 patients were carriers of a unique genotype. Most carriers were found in the internal medicine/nephrology and dialysis ward. Far-reaching measures (such as cohort nursing, admission stops, use of gowns and gloves, disinfection and restriction of use of vancomycin) taken in the four wards where spread was demonstrated, appeared effective but in three wards, spread was again demonstrated later. Frequent readmissions and transfers of patients appear to play an important part in this matter. None of the 51 colonized patients developed a serious VRE infection.     

Ultra-sonic nebulizers as a potential source of methicillin-resistant Staphylococcus aureus causing an outbreak in a university tertiary care hospital

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) occurred on a head and neck surgical (HNS) ward of a university hospital in Amsterdam. The outbreak lasted from May 2000 until November 2000, and MRSA spread to two intensive care units. Amplified fragment length polymorphism analysis indicated that a single clone was responsible for the outbreak. Phage-typing indicated that this clone was of a type that was uncommon in The Netherlands. Strict isolation of patients, according to the Dutch national guidelines, was instituted. During the outbreak, surveillance culture specimens, from patients, healthcare workers, and the environment, were obtained at regular intervals. MRSA was found in the dust filters of nebulizers through which air from the room was filtered and subsequently humidified. These nebulizers were used to humidify tracheostomies. The dust filters were not maintained according to the guidelines. Restricted use and cleaning and disinfection of all ultra-sonic nebulizers led to termination of the outbreak. The outbreak illustrates that to terminate transmission of outbreak strains of MRSA, meticulous measures are necessary, which not only include strict isolation precautions, but also decontamination of the environment. In addition, it demonstrates the necessity of adhering to cleaning and disinfection guidelines for all medical and nursing equipment used in the hospital.     

Effectiveness of a multifaceted infection control policy in reducing vancomycin usage and vancomycin-resistant enterococci at a tertiary care cancer centre

We undertook a prospective cohort study to evaluate the role of a multifaceted infection control policy including the use of a "vancomycin order form," in decreasing the transmission of vancomycin-resistant enterococci (VRE). In January 1997, a multifaceted infection-control policy was implemented amongst patients admitted to the M. D. Anderson Cancer Center in whom neutropenic fever developed or who were found to be colonized or infected with VRE. As part of this programme, we initiated the use of a vancomycin order form to reduce the use of empirical vancomycin. The total incidence of VRE infections declined from 0.437/1000 patient days in 1996-97 to 0.229/1000 patient days in 1998-99 (P=0.008). The VRE bloodstream infections declined from 0.338/1000 patient days in 1996-97 to 0.181/1000 patient days in 1998-99 (P=0.027). Empiric vancomycin use decreased from 416 g/1000 patient days in 1996-97 to 208 g/1000 patient days in 1998-99 (P<0.001), resulting in a decreased vancomycin cost from $2561 US dollars/1000 patient days in 1996-97 to $1195 US dollars/1000 patient days in 1997-98 (P<0.001). We conclude that a multifaceted infection control policy incorporating the use of a vancomycin order form can effectively decrease the use of empirical vancomycin and can play a role in limiting the spread of VRE in an endemic setting.     

Implications of colonization of vancomycin-resistant enterococci (VRE) in renal dialysis patients. Learning to live with it?

Vancomycin-resistant enterococci (VRE) commonly colonize, but less frequently infect, debilitated patients, such as those on chronic renal dialysis. The emergence of VRE amongst our cohort of renal replacement therapy patients posed considerable challenges in our attempts to prevent spread. Although 60 of 451 (13%) patients became colonized, only two patients required systemic antibiotics for confirmed or suspected invasive infection. Mortality and inpatient stay was greater in VRE-positive compared with VRE-negative patients (50% versus 10%) and patients who were screened on three or more occasions were likely to remain positive (e.g. 56% of patients screened on six occasions were positive). The application of recommended guidelines for the control of VRE, however, severely disrupted our renal dialysis programme and therefore had to be abandoned. As patients on renal dialysis are more likely to acquire VRE, remain colonized, require antibiotics and require regular inpatient or outpatient care more frequently than other patients, control measures should be adapted to minimize spread but not disrupt important and essential medical services.     

Effect of targeted surveillance for control of methicillin-resistant Staphylococcus aureus in a community hospital system.

OBJECTIVE: To examine the cost associated with targeted surveillance for methicillin-resistant Staphylococcus aureus (MRSA) and the effect of such surveillance on the rate of nosocomial MRSA infection in a community hospital system. DESIGN: A before-and-after study comparing the rate of MRSA infection before (BES) and after (AES) the initiation of expanded surveillance. Cost-effectiveness was calculated as the difference between the cost savings associated with preventing nosocomial MRSA bacteremias and surgical site infections AES and the cost of MRSA cultures and contact isolation for patients colonized with MRSA. SETTING AND PARTICIPANTS: Patients in a 400-bed tertiary-care facility (Roper Hospital) and a 180-bed suburban hospital (St. Francis Hospital), both in Charleston, South Carolina.Interventions. Beginning in September 2001, patients were screened for MRSA colonization upon admission to the intensive care unit and weekly thereafter. In July 2002, surveillance was expanded to include targeted screening of patients admitted to general wards who were at risk of MRSA colonization. Colonized patients were placed in contact isolation. RESULTS: The mean rate of nosocomial MRSA infection decreased at Roper (0.76 cases per 1,000 patient-days BES and 0.45 per 1000 patient-days AES; P = .05) and at St. Francis (0.73 cases per 1,000 patient-days BES and 0.57 cases per 1000 patient-days AES; P=.35). Surveillance was cost-effective, preventing 13 nosocomial MRSA bacteremias and 9 surgical site infections, for a savings of 1,545,762 US dollars. CONCLUSIONS: Targeted surveillance for MRSA colonization was cost-effective and provided substantial benefits by reducing the rate of nosocomial MRSA infections in a community hospital system.     

SHEA guideline for preventing nosocomial transmission of multidrug-resistant strains of Staphylococcus aureus and enterococcus.

BACKGROUND: Infection control programs were created three decades ago to control antibiotic-resistant healthcare-associated infections, but there has been little evidence of control in most facilities. After long, steady increases of MRSA and VRE infections in NNIS System hospitals, the Society for Healthcare Epidemiology of America (SHEA) Board of Directors made reducing antibiotic-resistant infections a strategic SHEA goal in January 2000. After 2 more years without improvement, a SHEA task force was appointed to draft this evidence-based guideline on preventing nosocomial transmission of such pathogens, focusing on the two considered most out of control: MRSA and VRE. METHODS: Medline searches were conducted spanning 1966 to 2002. Pertinent abstracts of unpublished studies providing sufficient data were included. RESULTS: Frequent antibiotic therapy in healthcare settings provides a selective advantage for resistant flora, but patients with MRSA or VRE usually acquire it via spread. The CDC has long-recommended contact precautions for patients colonized or infected with such pathogens. Most facilities have required this as policy, but have not actively identified colonized patients with surveillance cultures, leaving most colonized patients undetected and unisolated. Many studies have shown control of endemic and/or epidemic MRSA and VRE infections using surveillance cultures and contact precautions, demonstrating consistency of evidence, high strength of association, reversibility, a dose gradient, and specificity for control with this approach. Adjunctive control measures are also discussed. CONCLUSION: Active surveillance cultures are essential to identify the reservoir for spread of MRSA and VRE infections and make control possible using the CDC's long-recommended contact precautions.     

The best hospital practices for controlling methicillin-resistant Staphylococcus aureus: on the cutting edge.

OBJECTIVE: A performance improvement task force of Rhode Island infection control professionals was created to develop an epidemiologic model of statewide consistent infection control practices that could reduce the spread of methicillin-resistant Staphylococcus aureus (MRSA). DESIGN: This model encompasses screening protocols, isolation techniques, methods of cohorting positive patients, decolonization issues, postexposure follow-up, microbiology procedures, and standardized surveillance methodologies. These "best practice guidelines" include three categories of recommendations that define priority levels based on the availability of scientific data. SETTING: From 1995 through 2000, several Rhode Island hospitals experienced a fivefold increase in nosocomial acquisition of MRSA PARTICIPANTS: Rhode Island infection control professionals are a highly interactive group in the unique position of sharing patients and ultimately experiencing similar trends and problems. INTERVENTION: The task force collaborated on developing the best hospital infection control practices to prevent and control the spread of MRSA in Rhode Island. RESULTS: The task force met with local infectious disease physicians and representatives from the Rhode Island Department of Health, the Hospital Association of Rhode Island, and Rhode Island Quality Improvement Partners. Discussions identified numerous and diverse MRSA control practices, issues of consensus, and approaches to resolving controversial methods of reducing the spread of MRSA. The guidelines regarding the best hospital practices for controlling MRSA were finalized 8 months later. CONCLUSION: These guidelines were distributed to all chief executive officers of Rhode Island hospitals by the Rhode Island Department of Health in December 2001. They were issued separate and apart from any regulations, with the intent that hospitals will adopt them as best hospital practices in an attempt to control MRSA.     

Experience of vancomycin-resistant enterococci in a children's hospital

Vancomycin resistant enterococci (VRE) are increasingly important nosocomial pathogens. This paper describes our experience of the epidemiology and clinical impact of VRE in the two years since the occurrence of our first case of VRE infection. Following introduction of surveillance, gastrointestinal colonization with VRE was detected in 38.3% of Haematology/Oncology and 11.1% of Hepatology/Gastroenterology patients, but in only 2.3% of children in the Paediatric Intensive Care and 1.5% of children in the Renal Unit. Only five patients with gastrointestinal colonization subsequently developed clinical infection with VRE, giving an annual incidence of 7.5%. A further six children were colonized at extra-intestinal sites. Twelve children had clinical infections with VRE, of whom three (25%) died. Contamination of bedspaces was found in association with 2/3 (66.7%) children with extraintestinal colonization and 5/7 (71.4%) children with clinical infections, compared with 6/28 (21.4%) cases of gastrointestinal colonization. In the latter group, bedspace contamination was usually associated with widespread contamination of the ward with VRE and may have been the cause rather than the result of patients acquiring VRE. Originally we employed control measures based closely on the North American HICPAC guidelines, but our control strategy has since evolved in response to epidemiological and clinical observations.     

Nosocomial outbreak of vancomycin-resistant Enterococcus faecium at a German University Pediatric Hospital

Nosocomial Infections caused by vancomycin–resistant enterococci (VRE) are an emerging threat to critically ill patients. At the University Hospital Eppendorf, VRE were isolated from 38 patients between August 1993 and April 1997, of whom 32 were hospitalized at the Department of Pediatrics. Pulsed-field gel electrophoresis revealed that 26 Enterococcus faecium isolates from patients of the Department of Pediatrics were identical or closely related, and that isolates from three additional patients of the same department were possibly related. All of these isolates were of vanA genotype. They were resistant to glycopeptides, ampicillin, ciprofloxacin, clindamycin, and erythromycin. Most isolates displayed high–level resistance to gentamicin, but all remained susceptible to quinupristin/dalfopristin. Implementation of stringent hand disinfection and environmental disinfection policies, as well as measures for patient isolation contained this first outbreak of VRE at a German Children's hospital, which emphasizes the importance of hygienic measures for the control of nosocomial spread of these organisms.