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

A systematic review of the effectiveness of cohorting to reduce transmission of healthcare-associated C. difficile and multidrug-resistant organisms

BACKGROUND

Cohorting of patients and staff is a control strategy often used to prevent the spread of infection in healthcare institutions. However, a comprehensive evaluation of cohorting as a prevention approach is lacking.

METHODS

We performed a systematic review of studies that used cohorting as part of an infection control strategy to reduce hospital-acquired infections. We included studies published between 1966 and November 30, 2019, on adult populations hospitalized in acute-care hospitals.

RESULTS

In total, 87 studies met inclusion criteria. Study types were quasi-experimental "before and after" (n = 35), retrospective (n = 49), and prospective (n = 3). Case-control analysis was performed in 7 studies. Cohorting was performed with other infection control strategies in the setting of methicillin-resistant Staphylococcus aureus (MRSA, n = 22), Clostridioides difficile infection (CDI, n = 6), vancomycin-resistant Enterococcus (VRE, n = 17), carbapenem-resistant Enterobacteriaceae infections (CRE, n = 22), A. baumannii (n = 15), and other gram-negative infections (n = 5). Cohorting was performed either simultaneously (56 of 87, 64.4%) or in phases (31 of 87, 35.6%) to help contain transmission. In 60 studies, both patients and staff were cohorted. Most studies (77 of 87, 88.5%) showed a decline in infection or colonization rates after a multifaceted approach that included cohorting as part of the intervention bundle. Hand hygiene compliance improved in approximately half of the studies (8 of 15) during the respective intervention.

CONCLUSION

Cohorting of staff, patients, or both is a frequently used and reasonable component of an enhanced infection control strategy. However, determining the effectiveness of cohorting as a strategy to reduce transmission of MDRO and C. difficile infections is difficult, particularly in endemic situations.

New applications of a portable isolation hood for use in several settings and as a clean hood

Background

We previously reported that we developed a compact and portable isolation hood that covers the top half of a patient sitting or lying in bed. The negative pressure inside the hood is generated by a fan-filter-unit (FFU) through which infectious aerosols from a patient are filtered. The outside area is kept clean which decreases the risk of nosocomial infections in hospital wards. We tried new applications of the hood.

Methods

The negative pressure hood was newly applied in an intensive care unit (ICU) as a place where a staff performs the practice of suctioning that generates much aerosol from the patient, as well as a waiting space for patients. Furthermore, the possibility that the hood can be converted to a positive pressure hood as a clean hood by switching the airflow direction of FFU was assessed. The cleaning efficacy of the inside of the hood was tested using an aerosolized cultured influenza virus tracer and an optimal airflow rate was determined according to the test results.

Results

The hood, named Barrihood, was found to be competent to be used (I) for tracheal suctioning in ICU, (II) as a waiting space for a child in a nursery who suddenly showed symptoms of the disease and waiting to be picked-up by the guardian, and (III) as a waiting space in a special outpatient clinic in a hospital for COVID-19 suspected cases to prevent dissemination of airborne pathogens. The positive pressure hood was also competent in keeping clean air quality that meets the standard class 100 of NASA's bio-clean room category.

Conclusions

The proposed new applications will broaden the range of the hood's usage. The isolation hood could be useful in many settings to protect people outside the hood from a patient inside, or to protect an individual inside from air particles outside the hood, such as airborne pathogens, allergens, or hazardous particulate matter like PM2.5.

Development of a lightweight, 'on-bed', portable isolation hood to limit the spread of aerosolized influenza and other pathogens

Background

The annual seasonal influenza epidemics in the winter season lead to many hospital admissions, increasing risks of nosocomial infections. Infectious diseases caused by contagious respiratory pathogens also pose a great risk to hospitals as has been seen in the current epidemic by a novel coronavirus infection. Such risk occurs in high density patient settings with few or no partitions, since the pathogens are transmitted by aerosols discharged from the patients. Possible interventions against the transmission are needed.

Methods

We developed a compact, lightweight, and portable hood designed to cover just the top half of a patient sitting or lying in bed, to limit the dissemination of infectious aerosols, constructed out of lightweight pipes, transparent plastic curtains, and a fan-filter-unit (FFU). The containment efficacy of the product was tested using an aerosolized cultured influenza virus tracer and an optimal airflow rate was determined according to the test results. It was tested for use in hospital wards during the 2016–2018 influenza seasons.

Results

The hood, named as Barrihood^®, had dimensions height 172 cm, width 97 cm, length 38 cm, weighed 26 kg, and easily strolled and unfolded from its stored to its fully operational state of length 125 cm within a few minutes by a single operator. Optimal operational airflow-rate of the FFU was 420 L/min for containment of the aerosol particles. Eighty-one uninfected patients remained for 176 cumulative person-days within 1–4 m of influenza-infected patients isolated within the hood, without acquiring influenza infection.

Conclusions

With the use of the hood, secondary influenza infection cases significantly decreased, compared to previous influenza seasons. It may be suited to hospitals with not enough/no negative pressure facilities, or without enough number of individual patient isolation rooms, and could contribute to decrease the risk of nosocomial infections.

A Discrete Event Simulation Model of Patient Flow in a General Hospital Incorporating Infection Control Policy for Methicillin-Resistant Staphylococcus Aureus (MRSA) and Vancomycin-Resistant Enterococcus (VRE)

BACKGROUND

Hospitalized patients are assigned to available staffed beds based on patient acuity and services required. In hospitals with double-occupancy rooms, patients must be additionally matched by gender. Patients with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) must be bedded in single-occupancy rooms or cohorted with other patients with similar MRSA/VRE flags.

METHODS

We developed a discrete event simulation (DES) model of patient flow through an acute care hospital. Patients are matched to beds based on acuity, service, gender, and known MRSA/VRE colonization. Outcomes included time to bed arrival, length of stay, patient-bed acuity mismatches, occupancy, idle beds, acuity-related transfers, rooms with discordant MRSA/VRE colonization, and transmission due to discordant colonization.

RESULTS

Observed outcomes were well-approximated by model-generated outcomes for time-to-bed arrival (6.7 v. 6.2 to 6.5 h) and length of stay (3.3 v. 2.9 to 3.0 days), with overlapping 90% coverage intervals. Patient-bed acuity mismatches, where patient acuity exceeded bed acuity and where patient acuity was lower than bed acuity, ranged from 0.6 to 0.9 and 8.6 to 11.1 mismatches per h, respectively. Values for observed occupancy, total idle beds, and acuity-related transfers compared favorably to model-predicted values (91% v. 86% to 87% occupancy, 15.1 v. 14.3 to 15.7 total idle beds, and 27.2 v. 22.6 to 23.7 transfers). Rooms with discordant colonization status and transmission due to discordance were modeled without an observed value for comparison. One-way and multi-way sensitivity analyses were performed for idle beds and rooms with discordant colonization.

CONCLUSIONS

We developed and validated a DES model of patient flow incorporating MRSA/VRE flags. The model allowed for quantification of the substantial impact of MRSA/VRE flags on hospital efficiency and potentially avoidable nosocomial transmission.

Management of Inpatients Colonized or Infected With Antimicrobial-Resistant Bacteria in Hospitals in the United States

Background:

Although guidelines for multidrug-resistant organisms generally include recommendations for contact precautions and surveillance cultures, it is not known how frequently U.S. hospitals implement these measures on a routine basis and whether infectious diseases consultants endorse their use.

Methods:

The Emerging Infections Network surveyed its members, infectious diseases consultants, to assess their use of and support for contact precautions and surveillance cultures for routine management of multidrug-resistant organisms in their principal inpatient workplace. Specifically, members were asked about use of these strategies for methicillin-resistantStaphylococcus aureus, vancomycin-resistant enterococci, and multidrug-resistant, gram-negative bacilli on general wards, ICUs, and transplant units.

Results:

Overall, 400 (86%) of 463 respondents supported the routine use of contact precautions to control one or more multidrug-resistant organisms in at least one unit, and 89% worked in hospitals that use them. In contrast, 50% of respondents favored routine use of surveillance cultures to manage at least one multidrug-resistant organism in any unit, and 30% of respondents worked in hospitals that use them routinely in any unit. Members favored routine use of surveillance cultures significantly more in ICUs and transplant units than in general wards for each multidrug-resistant organism (P<.001).

Conclusions:

Most of the infectious diseases consultants endorsed the use of contact precautions for routine management of patients colonized or infected with multidrug-resistant organisms and work in hospitals that have implemented them. In contrast, infectious diseases consultants are divided about the role of routine surveillance cultures in multidrug-resistant organism management, and few work in hospitals that use them.

The Impact of a Single Ward for Cohorting Patients with Infection due to Multidrug-Resistant Organisms

Multidrug-resistant organisms (MDROs) are emerging and disseminating around the globe. The guidelines for the management of MDROs support the use of various interventions to reduce the burden of MDROs. We conducted a study to assess the impact of the creation of a unit for cohorting of patients with infection due to MDROs.

Hospital de Clínicas de Porto Alegre, a 795-bed university, public hospital, is located in the city of Porto Alegre in southern Brazil. In a quasi-experimental study, we assessed the impact of the creation of an MDRO unit for patient cohorting on the overall hospital incidence of infection due to MDROs.

The 34 beds of the unit were located in 16 rooms for adult MDRO-infected patients and 2 additional rooms for respiratory isolation. Patients were transferred to the unit when they were identified as infected or colonized with MDROs. The unit staff was trained for MDRO-infected patient care; unit staff, patients, and families attended weekly meetings for education about MDROs with a multidisciplinary team (doctors, nurses, pharmacists, and social assistants).

Emergence of Vancomycin-Resistant Enterococci in San Francisco Bay Area Hospitals During 1994 to 1998

Objective:

To determine the magnitude of van-comycin-resistant enterococci (VRE) in three counties in the San Francisco Bay area.

Design:

Active laboratory-based surveillance for VRE from January 1995 through December 1996 and a laboratory-based and hospital-based questionnaire survey for 1993 to 1994 and 1997 to 1998.

Setting:

All 33 general acute care hospitals in three counties in the San Francisco Bay area.

Participants:

Laboratories and infection control professionals serving these hospitals, and staff of the California Emerging Infections Program.

Results:

The number of hospitals reporting 1 or more patient clinical VRE isolates was 1 (3%) in 1993, 7 (21%) in 1994, 31 (94%) in 1995, and 33 (100%) in 1996 to 1998. The number of patient isolates increased from 1 in 1993 to 24 in 1994, 176 in 1995,429 in 1996, 730 in 1997, and 864 in 1998. Most VRE isolates in 1995 and 1996 were from urine and were not associated with serious clinical disease. However, the number of isolates from blood increased from 9 (6% of total) in 1995 to 44 (12% of the total) in 1996, 90 (14%) in 1997, and 100 (13%) in 1998.

Conclusions:

Our data document the rapid emergence and increase of VRE in all hospitals in three counties in the San Francisco Bay area during 1994 to 1998. Infection control measures for VRE together with antibiotic utilization programs should be implemented to limit further spread.

Legislative Mandates for Use of Active Surveillance Cultures to Screen for Methicillin-ResistantStaphylococcus aureusand Vancomycin-Resistant Enterococci: Position Statement From the Joint SHEA and APIC Task Force

Legislation aimed at controlling antimicrobial-resistant pathogens through the use of active surveillance cultures to screen hospitalized patients has been introduced in at least 2 US states. In response to the proposed legislation, the Society for Healthcare Epidemiology of America (SHEA) and the Association of Professionals in Infection Control and Epidemiology (APIC) have developed this joint position statement. Both organizations are dedicated to combating healthcare-associated infections with a wide array of methods, including the use of active surveillance cultures in appropriate circumstances. This position statement reviews the proposed legislation and the rationale for use of active surveillance cultures, examines the scientific evidence supporting the use of this strategy, and discusses a number of unresolved issues surrounding legislation mandating use of active surveillance cultures. The following 5 consensus points are offered. (1) Although reducing the burden of antimicrobial-resistant pathogens, including methicillin-resistantStaphylococcus aureus(MRSA) and vancomycin-resistant enterococci (VRE), is of preeminent importance, APIC and SHEA do not support legislation to mandate use of active surveillance cultures to screen for MRSA, VRE, or other antimicrobial-resistant pathogens. (2) SHEA and APIC support the continued development, validation, and application of efficacious and cost-effective strategies for the prevention of infections caused by MRSA, VRE, and other antimicrobial-resistant and antimicrobial-susceptible pathogens. (3) APIC and SHEA welcome efforts by healthcare consumers, together with private, local, state, and federal policy makers, to focus attention on and formulate solutions for the growing problem of antimicrobial resistance and healthcare-associated infections. (4) SHEA and APIC support ongoing additional research to determine and optimize the appropriateness, utility, feasibility, and cost-effectiveness of using active surveillance cultures to screen both lower-risk and high-risk populations. (5) APIC and SHEA support stronger collaboration between state and local public health authorities and institutional infection prevention and control experts.

Institutional Control Measures to Curtail the Epidemic Spread of Carbapenem-Resistant Klebsiella pneumoniae: A 4-Year Perspective

Objective.

To describe the implementation of an institution-wide, multiple-step intervention to curtail the epidemic spread of carbapenem-resistant Klebsiella pneumoniae (CRKP).

Design.

Consecutive intervention analyses.

Patients and Setting.

All patients admitted to a 775-bed tertiary care medical center in Jerusalem, Israel, from 2006 through 2010.

Interventions.

The effects of 4 interventions were assessed: (1) a policy of isolation for patients colonized or infected with CRKP in single rooms, which was started in March 2006; (2) cohorting of CRKP patients with dedicated nursing staff and screening of patients neighboring a patient newly identified as a carrier of CRKP, which was started in March 2007; (3) weekly active surveillance of intensive care unit patients, which was started during August 2008; and (4) selective surveillance of patients admitted to the emergency department, which was started in March 2009. Interrupted regression analysis and change-point analysis were used to assess the effect of each intervention on the CRKP epidemic.

Results.

Patient isolation alone failed to control the spread of CRKP, with incidence increasing to a peak of 30 new cases per 1,000 hospital beds per month. Institution of patient cohorting led to a steep decline in the incidence of CRKP acquisition (P< .001). Introduction of active surveillance interventions was followed by a decrease in the incidence of CRKP-positive clinical cultures but an increase in the incidence of CRKP-positive screening cultures. The mean prevalence of CRKP positivity for the period after cohorting began showed a statistically significant change from the mean prevalence in the preceding period (P< .001).

Conclusions.

The cohorting of patients with dedicated staff, combined with implementation of focused active surveillance, effectively terminated the epidemic spread of CRKP. Cohorting reduced cross-infection within the hospital, and active surveillance allowed for earlier detection of carrier status. Both interventions should be considered in attempts to contain a hospital epidemic.

Comorbidities and disease severity as risk factors for carbapenem-resistant Klebsiella pneumoniae colonization: report of an experience in an internal medicine unit

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an emerging multidrug-resistant nosocomial pathogen, spreading to hospitalized elderly patients. Risk factors in this setting are unclear. Our aims were to explore the contribution of multi-morbidity and disease severity in the onset of CRKP colonization/infection, and to describe changes in epidemiology after the institution of quarantine-ward managed by staff-cohorting.

Methods and Findings

With a case-control design, we evaluated 133 CRKP-positive patients (75 M, 58 F; mean age 79±10 years) and a control group of 400 CRKP-negative subjects (179 M, 221 F; mean age 79±12 years) admitted to Internal Medicine and Critical Subacute Care Unit of Parma University Hospital, Italy, during a 10-month period. Information about comorbidity type and severity, expressed through Cumulative Illness Rating Scale-CIRS, was collected in each patient. During an overall 5-month period, CRKP-positive patients were managed in an isolation ward with staff cohorting. A contact-bed isolation approach was established in the other 5 months. The effects of these strategies were evaluated with a cross-sectional study design. CRKP-positive subjects had higher CIRS comorbidity index (12.0±3.6 vs 9.1±3.5, p<0.0001) and CIRS severity index (3.2±0.4 vs 2.9±0.5, p<0.0001), along with higher cardiovascular, respiratory, renal and neurological disease burden than control group. CIRS severity index was associated with a higher risk for CRKP-colonization (OR 13.3, 95%CI6.88–25.93), independent of comorbidities. Isolation ward activation was associated with decreased monthly incidence of CRKP-positivity (from 16.9% to 1.2% of all admissions) and infection (from 36.6% to 22.5% of all positive cases; p = 0.04 derived by Wilcoxon signed-rank test). Mortality rate did not differ between cases and controls (21.8% vs 15.2%, p = 0.08). The main limitations of this study are observational design and lack of data about prior antibiotic exposure.

Conclusions

Comorbidities and disease severity are relevant risk factors for CRKP-colonization/infection in elderly frail patients. Sanitary measures may have contributed to limit epidemic spread and rate of infection also in internal medicine setting.

Quarantine, isolation, and cohorting: from cholera to Klebsiella

BACKGROUND

Isolation is defined as the separation of persons with communicable diseases from those who are healthy. This public health practice, along with quarantine, is used to limit the transmission of infectious diseases and provides the foundation of current-day cohorting.

METHODS

Review of the pertinent English-language literature.

RESULTS

Mass isolation developed during the medieval Black Death outbreaks in order to protect ports from the transmission of epidemics. In the mid-1800s, infectious disease hospitals were opened. It now is clear that isolation and cohorting of patients and staff interrupts the transmission of disease. Over the next century, with the discovery of penicillin and vaccines against many infectious agents, the contagious disease hospitals began to close. Today, we find smaller outbreaks of microorganisms that have acquired substantial resistance to antimicrobial agents. In the resource-limited hospital, a dedicated area or region of a unit may suffice to separate affected from unaffected patients.

CONCLUSION

Quarantine, or cohorting when patients are infected with the same pathogen, interrupts the spread of infections, just as the contagious disease hospitals did during the epidemics of the 18th and 19th centuries.

Health care-associated infection outbreak investigations by the Centers for Disease Control and Prevention, 1946-2005

Since 1946, Centers for Disease Control and Prevention (CDC) personnel have investigated outbreaks of infections and adverse events associated with delivery of health care. CDC Epidemic Intelligence Service officers have led onsite investigations of these outbreaks by systematically applying epidemiology, statistics, and laboratory science. During 1946-2005, CDC Epidemic Intelligence Service officers conducted 531 outbreak investigations in facilities across the United States and abroad. Initially, the majority of outbreaks involved gastrointestinal tract infections; however, in later years, bloodstream, respiratory tract, and surgical wound infections predominated. Among pathogens implicated in CDC outbreak investigations, Staphylococcus aureus, Enterococcus species, Enterobacteriaceae, nonfermentative Gram-negative bacteria, or yeasts predominated, but unusual organisms (e.g., the atypical mycobacteria) were often included. Outbreak types varied and often were linked to transfer of colonized patients or health care personnel between facilities (multihospital outbreaks), national distribution of contaminated products, use of invasive medical devices, or variances in practices and procedures in health care environments (e.g., intensive care units, water reservoirs, or hemodialysis units). Through partnerships with health care facilities and local and state health departments, outbreaks were terminated and lives saved. Data from investigations invariably contributed to CDC-generated guidelines for prevention and control of health care-associated infections.

Effective cohorting and "superisolation" in a single intensive care unit in response to an outbreak of diverse multi-drug-resistant organisms

BACKGROUND

Cohorting patients in dedicated hospital wards or wings during infection outbreaks reduces transmission of organisms, yet frequently, this may not be feasible because of inadequate capacity, especially in the intensive care unit (ICU). We hypothesized that cohorting isolation patients in one geographic location in a single ICU and using enhanced isolation procedures ("superisolation") can prevent the further spread of highly multi-drug-resistant organisms (MDRO).

METHODS

Six patients dispersed throughout our Surgical Trauma Burn ICU had infections with carbapenem-resistant, non-clonal gram-negative MDRO, namely Klebsiella pneumoniae, Citrobacter freundii, Stenotrophomonas maltophilia, Aeromonas hydrophilia, Proteus mirabilis, Pseudomonas aeruginosa, and Providencia rettgeri. Five of the six patients also had simultaneous isolation of vancomycin-resistant enterococci (VRE). Under threat of unit closure and after all standard isolation procedures had been enacted, these six patients were moved to the front six beds of the unit, the front entrance was closed, and all traffic was redirected through the back entrance. Nursing staff were assigned to either two isolation or two non-isolation patients. In accordance with the practice of Semmelweis, rounds were conducted so as to end at the rooms of the patients with the most highly-resistant bacterial infections.

RESULTS

A few months after these interventions, all six patients had been discharged from the ICU (three alive and three dead), and no new cases of infection with any of their pathogens (based on species and antibiogram) or VRE occurred. The mean ICU stay and overall hospital length of stay for these six patients were 78.3 days and 117.2 days respectively, with a mortality rate of 50%.

CONCLUSION

Cohorting patients to one area and altering work routines to minimize contact with patients with MDRO (essentially designating a "high-risk" zone) may be beneficial in stopping patient-to-patient spread of highly resistant bacteria without the need for a dedicated isolation unit.

Increased risk of vancomycin-resistant enterococcus (VRE) infection among patients hospitalized for inflammatory bowel disease in the United States

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) infection has become an increasingly common hospital-acquired infection in U.S. hospitals. Patients with inflammatory bowel disease (IBD) frequently require hospitalization and therefore may be at increased risk of nosocomial infections.

METHODS

We used the Nationwide Inpatient Sample (NIS) to identify admissions for IBD (n = 116,842) between 1998 and 2004. We compared the prevalence of VRE in this group to that of non-IBD gastrointestinal (GI) inpatients and general inpatients and assessed for associations between VRE and hospital mortality, length of stay, and total charges.

RESULTS

The crude VRE prevalence was 2.1/10,000 in hospitalized IBD patients, 1.3/10,000 in non-IBD GI patients, and 0.9/10,000 in general inpatients. After adjustment for confounders, IBD inpatients were at increased risk of VRE compared to the non-IBD GI (adjusted odds ratio [aOR] 1.65; 95% confidence interval [CI]: 1.03-2.64) and general inpatient (aOR 2.37; 95% CI: 1.31-4.27) groups. Among IBD patients, there was a higher prevalence of VRE infection in those who had surgery (4.4/10,000 versus 1.7/10,000; P < 0.04) and total parenteral nutrition (6.9/10,000 versus 1.8/10,000; P < 0.003). VRE infection was not associated with an increase in mortality (0% versus 0.7%, P = 0.8); however, it was associated with 3-fold higher total hospital charges ($63,517 versus $21,918 USD; P < 0.0001) and increased average length of stay in hospital (16.1 versus 6.1 days; P < 0.0001).

CONCLUSIONS

Hospitalized IBD patients have increased susceptibility to VRE that is associated with increased economic burden. This study reinforces the importance of measures to prevent nosocomial infection, particularly in the vulnerable IBD population.

Controlling antimicrobial resistance in the hospital

Most evidence-based methods to control the spread of antimicrobial resistance have been developed and applied to the hospital setting. Strategies to control the emergence and spread of antimicrobial resistance in hospitals can be categorized as either infection control or antibiotic stewardship strategies. Infection control is the discipline focused on preventing the spread of infections within the health care setting; antibiotic stewardship can help minimize the emergence of multidrug-resistant organisms by promoting prudent use of antibiotics. This article describes different infection control and antibiotic management strategies that can be used to control antimicrobial resistance in hospital settings.

Epidemiology and control of an outbreak of vancomycin-resistant enterococci in the intensive care units

PURPOSE

This study was aimed to describe a vancomycin-resistant enterococci (VRE) outbreak across three intensive care units (ICUs) of a Korean hospital from September 2006 to January 2007 and the subsequent control strategies.

MATERIALS AND METHODS

We simultaneously implemented multifaceted interventions to control the outbreak, including establishing a VRE cohort ward, active rectal surveillance cultures, daily extensive cleaning of environmental surfaces and environmental cultures, antibiotic restriction, and education of hospital staff. We measured weekly VRE prevalence and rectal acquisition rates and characterized the VRE isolates by polymerase chain reaction (PCR) of the vanA gene and Sma1-pulsed-field gel electrophoresis (PFGE).

RESULTS

During the outbreak, a total of 50 patients infected with VRE were identified by clinical and surveillance cultures, and 46 had vancomycin-resistant Enterococcus faecium (VREF). PFGE analysis of VREF isolates from initial two months disclosed 6 types and clusters of two major types. The outbreak was terminated 5 months after implementation of the interventions: The weekly prevalence rate decreased from 9.1/100 patients-day in September 2006 to 0.6/100 by the end of January 2007, and the rectal acquisition rates also dropped from 6.9/100 to 0/100 patients-day.

CONCLUSION

Our study suggests that an aggressive multifaceted control strategy is a rapid, effective approach for controlling a VRE outbreak.

Compliance in cystic fibrosis: an examination of infection control guidelines

The goal of this research was to begin the process of evaluating acceptability of infection control (IC) recommendations to CF patients and their families, determine whether compliance with IC guidelines differs from compliance with traditional CF medical treatment with respect to the variables predictive of compliance, and assess which patients are most likely to comply with IC recommendations. Participants were recruited during routine outpatient visits at a regional CF center located in a pediatric hospital. The sample included 44 child and adolescent patients, aged 9-18 years and their guardian, and 27 adult patients. All patients completed questionnaires and interviews. Results of this preliminary study suggest that many individuals with CF are unaware of or unconcerned with the risks involved in infection transmission via social contact with other CF patients. Further, most participants reported that they could benefit from friendships with other CF patients. Health belief variables were found to be predictive of compliance with both IC guidelines and traditional medical treatments in the adult and parent sample, but not in the child sample. Possible explanations for study findings are discussed and recommendations for future research on IC compliance are highlighted.

Legislative mandates for use of active surveillance cultures to screen for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci: Position statement from the Joint SHEA and APIC Task Force

Legislation aimed at controlling antimicrobial-resistant pathogens through the use of active surveillance cultures to screen hospitalized patients has been introduced in at least 2 US states. In response to the proposed legislation, the Society for Healthcare Epidemiology of America (SHEA) and the Association for Professionals in Infection Control and Epidemiology, Inc., (APIC) have developed this joint position statement. Both organizations are dedicated to combating health care-associated infections with a wide array of methods, including the use of active surveillance cultures in appropriate circumstances. This position statement reviews the proposed legislation and the rationale for use of active surveillance cultures, examines the scientific evidence supporting the use of this strategy, and discusses a number of unresolved issues surrounding legislation mandating use of active surveillance cultures. The following 5 consensus points are offered. (1) Although reducing the burden of antimicrobial-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), is of preeminent importance, the APIC and the SHEA do not support legislation to mandate use of active surveillance cultures to screen for MRSA, VRE, or other antimicrobial-resistant pathogens. (2) The SHEA and the APIC support the continued development, validation, and application of efficacious and cost-effective strategies for the prevention of infections caused by MRSA, VRE, and other antimicrobial-resistant and antimicrobial-susceptible pathogens. (3) The APIC and the SHEA welcome efforts by health care consumers, together with private, local, state, and federal policy makers, to focus attention on and formulate solutions for the growing problem of antimicrobial resistance and health care-associated infections. (4) The SHEA and the APIC support ongoing additional research to determine and optimize the appropriateness, utility, feasibility, and cost-effectiveness of using active surveillance cultures to screen both lower-risk and high-risk populations. (5) The APIC and the SHEA support stronger collaboration between state and local public health authorities and institutional infection prevention and control experts.

Prävention und Kontrolle der Ausbreitung von Vancomycin-resistenten Enterokokken

The incidence of vancomycin-resistant enterococci (VRE), especially E. faecium, is increasing in several German hospitals and some facilities have experienced VRE outbreaks. The German National Nosocomial Infection Surveillance System has also noticed a sharp increase in the incidence of nosocomial VRE infections per 10,000 patients from 0.5 in 2003 to 11.0 in 2005 accompanied by a rise in VRE-associated mortality. However, the reasons of this increase remain unknown. As VRE may cause severe nosocomial infections, transmission must be restricted. This article provides the guidelines as defined by the workshop of the German Society for Hygiene and Microbiology for the prevention of VRE transmission in both, endemic and epidemic, settings. The following topics are discussed: indication for VRE screening, microbiological diagnostics, general infection control measures (isolation precautions and use of protective clothing) and additional hygiene measures in the nosocomial VRE outbreak setting.

Effectiveness of barrier precautions and surveillance cultures to control transmission of multidrug-resistant organisms: a systematic review of the literature

BACKGROUND

Despite the priority placed on preventing transmission of multidrug-resistant organisms (MDROs) in health care facilities, there is a lack of consensus among recommended infection control guidelines. We focused on control measures that have a great potential to affect patient care, patient services, and hospital cost/resources: barrier precautions/patient isolation and surveillance cultures.

METHODS

We conducted a systematic review of the literature and published English-language guidelines pertaining to the use of barrier precautions/patient isolation and surveillance cultures to prevent the transmission of MDROs. The recommendations made by the published guidelines were summarized and compared. The primary research studies identified through our literature search were evaluated for study quality. We then summarized the outcomes of the studies with the highest quality scores and made recommendations for future work.

RESULTS

A total of 29 studies were included in our assessment of study quality; of those, 7 studies were of high quality.

CONCLUSION

This systematic review identified key gaps in the literature including a need for greater monitoring of implementation of the interventions, more cost analyses of interventions, determining the independent contribution of specific interventions, and identifying the minimum interventions needed to reduce transmission.

Preventing Transmission of Multidrug-Resistant Bacteria in Health Care Settings: A Tale of Two Guidelines

Two guidelines for the control of multidrug-resistant organisms in health care facilities have appeared during the past 3 years--one from the Society for Healthcare Epidemiology of America and one, in draft form, from the Healthcare Infection Control Practices Advisory Committee of the Centers for Disease Control and Prevention. These guidelines reflect universal concern in the infection-control community about today's unprecedented levels of activity of multidrug-resistant organisms and about inadequate or inconsistent application of potentially effective control measures. The 2 guidelines provide detailed reviews of pertinent issues and evidence-based, rated recommendations, which overlap considerably. Recommendations regarding indications for active surveillance cultures and the extent of their use constitute the major divergence. Although implementation of comprehensive control plans for multidrug-resistant organisms advocated by both guidelines will require health care facilities to confront difficult programmatic issues, aggressive and widespread adoption of control measures for multidrug-resistant organisms is urgently needed.

Identification of glycopeptide-resistant enterococci by VITEK 2 system and conventional and real-time polymerase chain reaction

Glycopeptide-resistant enterococci (GRE) are important causes of nosocomial infections in the United States and in Europe. Rapid detection of GRE is essential for the implementation of appropriate control measures to prevent the spread of GRE. In this study, we compared the reliability of 3 different methods, VITEK 2 automated system (bioMérieux), a conventional multiplex polymerase chain reaction (m-PCR) protocol, and a real-time PCR protocol performed on the LightCycler system (Roche) for identification of GRE in the routine microbiology laboratory. Species identification and glycopeptide resistance determination was tested with 80 enterococcal isolates with different glycopeptide resistance phenotypes. With the VITEK 2 system, 39% of the strains were correctly identified to species level. Resistance to vancomycin was detected in all isolates; however, discrepancies occurred in the correct detection of teicoplanin resistance. The PCR protocols proved to be suitable for detecting clinically relevant GRE; 90% of the isolates studied were correctly identified with the conventional m-PCR and 100% of vanA and vanB isolates with the real-time PCR protocol, respectively. High specificity and rapidity make the real-time PCR assays superior tools for identification of GRE in clinical samples; however, they do not have the ability to detect vanC.

Three surveillance strategies for vancomycin-resistant enterococci in hospitalized patients: detection of colonization efficiency and a cost-effectiveness model

OBJECTIVE

To evaluate the cost-effectiveness and detection sensitivity associated with three active surveillance strategies for the identification of patients harboring vancomycin-resistant enterococci (VRE) to determine which is the most medically and economically useful.

DESIGN

Culture for VRE from 200 consecutive stool specimens submitted for Clostridium difficile culture. Following this, risk factors were assessed for patients whose culture yielded VRE, and a cost-effectiveness evaluation was performed using a decision analytic model with a probabilistic analysis.

SETTING

A 688-bed, tertiary-care facility in Chicago, Illinois, with approximately 39,000 annual admissions, 7,000 newborn deliveries, 56,000 emergency department visits, and 115,000 home care and 265,000 outpatient visits.

SUBJECTS

All stool specimens submitted to the clinical microbiology laboratory for C. difficile culture from hospital inpatients.

RESULTS

From 200 stool samples submitted for C. difficile testing, we identified 5 patients with VRE in non-high-risk areas not screened as part of our routine patient surveillance. Medical record review revealed that all 5 had been hospitalized within the prior 2 years. Three of 5 had a history of renal impairment. The strategy that would involve screening the greatest number of patients (all those with a history of hospital admission in the prior 2 years) resulted in highest screening cost per patient admitted (dollars 2.48), lower per patient admission costs (dollars 480), and the best survival rates.

CONCLUSION

An expanded VRE surveillance program that encompassed all patients hospitalized within the prior 2 years was a cost-effective screening strategy compared with a more traditional one focused on high-risk units.

Impact of a formulary switch from ticarcillin-clavulanate to piperacillin-tazobactam on colonization with vancomycin-resistant enterococci

BACKGROUND

The prevalence of vancomycin-resistant enterococci (VRE) is increasing, despite infection control measures. Limited data link ticarcillin-clavulanate to higher VRE prevalence.

METHODS

Active surveillance for VRE was conducted before and after a formulary switch from ticarcillin-clavulanate to piperacillin-tazobactam. Rectal swabs were obtained serially in 863 adult patients admitted to intensive care units (ICUs) between November 1, 2000 and September 30, 2004.

RESULTS

In the postswitch period, 38 of 497 (7.6%) patients acquired VRE versus 42 of 366 (11.5%) patients in the preswitch period. Survival analysis showed an overall hazard ratio (HR) of .68 postswitch versus preswitch ( P = .07), with the greatest change in the surgical ICU (HR = .17, P = .006). Multivariate analysis showed an overall HR = .51 ( P = .004). Hospital-wide, nonstool VRE clinical cultures fell from 39 (.58/1000 patient days) in the 10-month preswitch period to 27 (.33/1000 patient days) in the 12-month postswitch period. Infection control practices and use of other antibiotics remained stable.

CONCLUSIONS

VRE acquisition appeared to decrease in association with a formulary change from ticarcillin-clavulanate to piperacillin-tazobactam.

Antimicrobial susceptibility testing of vancomycin-resistant Enterococcus by the VITEK 2 system, and comparison with two NCCLS reference methods

We evaluated the automated VITEK 2 system (bioMérieux) for antimicrobial susceptibility testing of vancomycin-resistant Enterococcus (VRE). The results obtained with the VITEK 2 system were compared to those obtained using two NCCLS reference methods. The VITEK 2 system produced MICs for penicillin G, erythromycin and vancomycin that were very similar to those of the reference agar-dilution test with all results being within a twofold dilution. When MICs of teicoplanin for these isolates were measured by the agar-dilution method and VITEK 2 system, there was one ‘very major’ error and seven ‘minor’ errors. There were no ‘major’ errors for any of the antibiotics tested. When the results obtained by the micro broth-dilution method were compared with those obtained by the VITEK 2 system, there was one ‘very major’ error for teicoplanin by the VITEK 2 system, as was the case with the agar-dilution method. There were two ‘minor’ errors for erythromycin and seven ‘minor’ errors for teicoplanin. There were no ‘major’ errors for any of the antibiotics tested. The 35 VRE strains identified phenotypically by the VITEK 2 Advanced Expert System included nine of Enterococcus faecalis and 23 of Enterococcus faecium. Neither Enterococcus avium nor Enterococcus hirae were identified. A total of 32 phenotypes were classified into 22 VanA and 10 VanB strains. PCR genotyping demonstrated 23 vanA + and nine vanB + strains. There were differences between the VITEK 2 system results and those of PCR. Overall, 54.3 % of the test results were obtained within 7 h. All MIC values for the 35 VRE isolates were determined within 13 h of completing incubation. The VITEK 2 system is a simple method for accurately detecting vancomycin-resistant strains of Enterococcus and can be used to rapidly determine MICs.

Co-carriage rates of vancomycin-resistant Enterococcus and extended-spectrum beta-lactamase-producing bacteria among a cohort of intensive care unit patients: implications for an active surveillance program

OBJECTIVE

To assess the co-colonization rates of extended-spectrum beta-lactamase (ESBL)-producing bacteria and vancomycin-resistant Enterococcus (VRE) obtained on active surveillance cultures.

DESIGN

Prospective cohort study.

SETTING

Medical and surgical intensive care units (ICUs) of a tertiary-care hospital.

PATIENTS

Patients admitted between September 2001 and November 2002 to the medical and surgical ICUs at the University of Maryland Medical System had active surveillance perirectal cultures performed. Samples were concurrently processed for VRE and ESBL-producing bacteria.

RESULTS

Of 1,362 patients who had active surveillance cultures on admission, 136 (10%) were colonized with VRE. Among these, 15 (positive predictive value, 11%) were co-colonized with ESBL. Among the 1,226 who were VRE negative, 1,209 were also ESBL negative (negative predictive value, 99%). Among the 1,362 who had active surveillance cultures on admission, 32 (2%) were colonized with ESBL. Among these, 15 (47%) were co-colonized with VRE. Of the 32 patients colonized with ESBL, 10 (31%) had positive clinical cultures for ESBL on the same hospital admission. For these 10 patients, the surveillance cultures were positive an average of 2.7 days earlier than the clinical cultures.

CONCLUSIONS

Patients who are colonized with VRE can also be co-colonized with other antibiotic-resistant bacteria such as ESBL-producing bacteria. Our study is the first to measure co-colonization rates of VRE and ESBL-producing bacteria. Isolating VRE-colonized patients would isolate 47% of the ESBL-colonized patients without the need for further testing. Hence, active surveillance for VRE should also theoretically diminish the amount of patient-to-patient transmission of ESBL-producing bacteria.

Detection of Vancomycin‐Resistant Enterococci Before and After Antimicrobial Therapy: Use of Conventional Culture and Polymerase Chain Reaction

Antimicrobial therapy can increase the colonization density of gastrointestinal vancomycin-resistant enterococci (VRE). Among previously VRE-colonized patients, we evaluated VRE colonization before and after initiation of antimicrobial therapy by means of polymerase chain reaction (PCR) and culture. Perianal swab samples were obtained at admission to the hospital and after receipt of antimicrobial therapy. At admission, 12 (21%) of 56 patients were culture positive, and 17 (30%) had vanA or vanB genes detected by PCR. Culture results showed that 25 (86%) of 29 culture-negative patients from whom a second swab sample was obtained remained culture negative, 2 (6.9%) had a relapse of colonization with a strain related to the previously colonizing strain type (2 and 6 days after admission), and 2 (6.9%) tested positive for a previously undetected strain type (16 and 19 days after admission). PCR at admission detected VRE in 1 of the 2 patients who later relapsed. Patients with negative results of culture of the initial swab sample and of PCR were unlikely to relapse after receipt of antimicrobial therapy.

Inter-hospital dissemination of glycopeptide-resistant Enterococcus faecalis in Brazil

The antimicrobial susceptibility patterns of 73 glycopeptide-resistant Enterococcus faecalis isolates from nine hospitals in Brazil were analysed by the disk diffusion method and Etests. Isolates were typed by pulsed-field gel electrophoresis (PFGE), and vancomycin resistance genes were detected by PCR. The isolates shared a single major PFGE pattern, with six subtypes, and all were positive for vanA. These results indicate the occurrence of inter-hospital dissemination of glycopeptide-resistant E. faecalis in São Paulo, and raise concerns about the rapid dissemination of this pathogen throughout Brazil.

Comparison of PCR assay to culture for surveillance detection of vancomycin-resistant enterococci

Direct multiplex PCR assay using vanA and vanB primers, which provides rapid results, was more sensitive than culture on selective media for samples collected by rectal swab (20 of 46 versus 8 of 46; P < 0.001) or perianal swab (17 of 58 versus 12 of 58; P = 0.059) for the detection of gastrointestinal colonization by vancomycin-resistant enterococci.

Control of endemic vancomycin-resistant Enterococcus among inpatients at a university hospital

We sought to determine the ability of surveillance cultures and isolation of vancomycin-resistant Enterococcus (VRE)-colonized patients to control nosocomial VRE infection and colonization during a 5-year period (November 1994 through October 1999). During this period, VRE colonization was limited to 0.82% of admissions. The incidence of VRE infection was 0.12 cases per 1000 patient-days (attack rate, 0.07%). Colonized patients were first identified by surveillance (95%) or routine clinical cultures (5%); 14% of colonized patients had a positive clinical culture a median of 15 days after a positive surveillance culture. Ten percent of colonized patients were identified by surveillance at the time of transfer from another health care facility. Identification of these colonized patients was associated with reduction from a peak incidence rate of 2.07% to a rate of 1.25% and stabilization at this lower level. The use of surveillance cultures to identify and isolate patients with asymptomatic colonization can provide sustained control of the spread of VRE within a health care facility.

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.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

Vancomycin-resistant enterococci: a road map on how to prevent the emergence and transmission of antimicrobial resistance

Nosocomial acquisition of microorganisms resistant to multiple antibiotics represents a threat to patient safety. Here we review the mechanisms that have allowed highly resistant strains belonging to the Enterococcus genus to proliferate within our health-care institutions. These mechanisms indicate that decreasing the prevalence of resistant organisms requires active surveillance, adherence to vigorous isolation, hand hygiene and environmental decontamination measures, and effective antibiotic stewardship. We suggest how to tailor such a complex, multidisciplinary program to the needs of a particular health-care setting so as to maximize cost-effectiveness.

Cost-effectiveness of perirectal surveillance cultures for controlling vancomycin-resistant Enterococcus

BACKGROUND

Several hospitals opting not to use active surveillance cultures to identify carriers of vancomycin-resistant Enterococcus (VRE) have reported that adoption of other parts of the Centers for Disease Control and Prevention guideline for controlling VRE has had little to no impact. Because use of surveillance cultures and contact isolation controlled a large outbreak at this hospital, their costs were estimated for comparison with the excess costs of VRE bacteremias occurring at a higher rate at a hospital not employing these measures.

SETTING

Two university hospitals.

METHODS

Inpatients deemed high risk for VRE acquisition at this hospital underwent weekly perirectal surveillance cultures. Estimated costs of cultures and resulting isolation during a 2-year period were compared with the estimated excess costs of more frequent VRE bacteremias at another hospital of similar size and complexity not using surveillance cultures to control spread throughout the hospital.

RESULTS

Of 54,052 patients admitted, 10,400 had perirectal swabs taken. Cultures and isolation cost an estimated $253,099. VRE culture positivity was limited to 193 (0.38%) and VRE bacteremia to 1 (0.002%) as compared with 29 bacteremias at the comparison hospital. The estimated attributable cost of VRE bacteremia at the comparison hospital of $761,320 exceeded the cost of the control program at this hospital by threefold.

CONCLUSIONS

The excess costs of VRE bacteremia may justify the costs of preventive measures. The costs of VRE infections at other body sites, of deaths from untreatable infections, and of dissemination of genes for vancomycin resistance also help to justify the costs of implementing an effective control program.

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.

Nurses' experience with vancomycin-resistant enterococci (VRE)

The emergence and spread of resistant organisms, in particular vancomycin-resistant enterococci (VRE), is an issue facing all staff in acute hospitals. This study explored how nurses coped with the responsibility of halting further spread of this organism during an outbreak. VRE-positive patients were cohorted with nurses who cared for them in an endeavour to contain the spread of VRE. The majority of nurses found the situation extremely stressful because of the need to act as 'gatekeepers' responsible for educating and monitoring the practices of staff and visitors. The nurses reported that they felt they were inadequately supported, were blamed for the outbreak, and that they had an increased workload as they took on duties of other staff. The results reinforce the need for a multidisciplinary team approach to education and control of VRE, more support for nursing staff cohorted with VRE-positive patients, and stringent adherence to infection control measures by all hospital staff.

Consequences of inaction: importance of infection control practices

The increasing prevalence of antimicrobial-resistant pathogens in health care facilities is due in large part to overuse of antibiotics and poor compliance with recommended infection control practices. To control the spread of such pathogens, health care facilities must reduce overuse and abuse of antibiotics, and they must implement new multidisciplinary programs to improve hand hygiene practices among health care workers and improve compliance with recommended barrier precautions.

Vancomycin-resistant enterococci: mechanisms and clinical observations

Enterococci are not generally regarded as highly virulent bacterial pathogens. However, resistance to many antimicrobial drugs complicates treatment of enterococcal infections. Acquired resistance to high concentrations of glycopeptide antibiotics, specifically vancomycin, has exacerbated this problem. This article seeks to concisely review the mechanisms of that resistance and its effects on clinical management of enterococcal infections, as well as clinical microbiology and infection control.

Clinical and epidemiological features of Enterococcus casseliflavus/flavescens and Enterococcus gallinarum bacteremia: a report of 20 cases

The clinical significance of intrinsically vancomycin-resistant enterococci is not yet fully established, as these organisms are infrequently recovered from clinical specimens. We report our experience with 20 cases of Enterococcus gallinarum and Enterococcus casseliflavus/flavescens bacteremia in humans from 1992 through 1998. Sixteen cases of bacteremia were caused by E. gallinarum. Underlying conditions were present in 19 (95%) of the patients and included malignancy, receipt of transplant, and Caroli's disease. Polymicrobial bacteremia was present in 9 patients (45%). E. gallinarum and E. casseliflavus/flavescens, although they are infrequently isolated from clinical specimens, may cause serious invasive infections.