The National Nosocomial Infections Surveillance (NNIS) System personnel report trends in antimicrobial-resistant pathogens. To validate select antimicrobial susceptibility testing results and to identify test methods that tend to produce errors, we conducted proficiency testing among NNIS System hospital laboratories.

NNIS System hospital laboratories in the United States.

Each laboratory received five organisms (ie, an imipenem-resistant Serratia marcescens, an oxacillin-resistant Staphylococcus aureus, a vancomycin-resistant Enterococcus faecalis, a vancomycin-intermediate Staphylococcus epidermidis, and an extended-spectrum beta-lactamase (ESβL)-producing Klebsiella pneumoniae). Testing results were compared with reference testing results from the Centers for Disease Control and Prevention.

Of 138 laboratories testing imipenem against the Serratia marcescens strain, 110 (80%) correctly reported minimum inhibitory concentrations (MICs) or zone sizes in the resistant range. All 193 participating laboratories correctly reported the Staphylococcus aureus strain as oxacillin resistant. Of the 193 laboratories, 169 (88%) reported correct MICs or zone sizes for the vancomycin-resistant Enterococcus faecalis. One hundred sixty-two (84%) of 193 laboratories demonstrated the ability to detect a vancomycin-intermediate strain of Staphylococcus epidermidis; however, disk diffusion performed poorly when testing both staphylococci and enterococci with vancomycin. Although laboratory personnel correctly reported nonsusceptible extended-spectrum cephalosporins and aztreonam results for K. pneumoniae, only 98 (51%) of 193 correctly reported this organism as an ESβL producer.

Overall, NNIS System hospital laboratory personnel detected most emerging resistance patterns. Disk diffusion continues to be unreliable for vancomycin testing of staphylococci and must be used cautiously for enterococci. Further education on the processing of ESβL-producing organisms is warranted.

Because patients with vancomycin-resistant Enterococcus bacteremia (VREB) usually have a higher severity of illness, it has been unclear whether VREB is worse than vancomycin-susceptible Enterococcus bacteremia (VSEB).

Data on morbidity and case fatality rates and costs were pooled from studies comparing VREB and VSEB, identified by Medline (January 1986 to April 2002) and meeting abstracts. Heterogeneity across studies was assessed with contingency table chi-square. Multivariate analyses (MVAs) controlling for other predictors were evaluated.

Thirteen studies compared case-fatality rates of VREB and VSEB. VREB case fatality was significantly higher (48.9% vs 19%; RR, 2.57; CI95, 2.27 to 2.91; attributable mortality = 30%). Five studies compared VREB with VSEB when bacteremia was the direct cause of death; VREB case fatality was significantly higher (39.1% vs 21.8%; RR, 1.79; CI95, 1.28 to 2.5; attributable mortality = 17%). Four MVAs found significant increases in case-fatality rates (OR 2.10 to 4.0), 3 showed trends toward increase (OR, 1.74 to 3.34 with wide confidence intervals), and 3 with low statistical power found no difference. VREB recurred in 16.9% versus 3.7% with VSEB (P < .0001). Three studies reported significant increases in LOS, costs, or both with VREB.

Most studies have had inadequate sample size, inadequate adjustment for other predictors of adverse outcomes, or both, but available data suggest that VREB is associated with higher recurrence, mortality, and excess costs than VSEB including multiple studies adjusting for severity of illness.

To determine whether there were differences in the microbiologic etiologies of ventilator-associated pneumonia in different clinical settings.

Observational retrospective cohort study of microbiologic etiologies of ventilator-associated pneumonia from 1998 to 2001 in a multi-hospital system. Microbiologic results were compared between hospitals and between different intensive care units (ICUs) within hospitals.

Three hospitals—one pediatric teaching hospital, one adult teaching hospital, and one community hospital— in one healthcare system in the midwestern United States.

Patients at the target hospitals who developed ventilator-associated pneumonia and for whom microbiologic data were available.

Seven hundred fifty-three episodes of ventilator-associated pneumonia had culture data available for review. The most common organisms at all hospitals were Staphylococcus aureus (28.4%) and Pseudomonas aeruginosa (25.2%). The pediatric hospital had higher proportions of Escherichia coli (9.5% vs 2.3%; P < .001) and Klebsiella pneumoniae (13% vs 3.1%; P < .001) than did the adult hospitals. In the pediatric hospital, the pediatric ICU had higher P. aeruginosa rates than did the neonatal ICU (33.3% vs 17%; P = .01). In the adult hospitals, the surgical ICU had higher Acinetobacter baumannii rates (10.2% vs. 1.7%; P < .001) than did the other ICUs.

Microbiologic etiologies of ventilator-associated pneumonia vary between and within hospitals. Knowledge of these differences can improve selection of initial antimicrobial regimens, which may decrease mortality.

To describe the implementation of the Canadian contingency plan for viral hemorrhagic fever (VHF) in response to a suspected case.

A 300-bed, tertiary-care, university-affiliated hospital.

A 32-year-old Congolese woman admitted to the hospital with suspected VHF in February 2001. Contact evaluation included hospital healthcare workers and laboratory staff.

Enhanced isolation precautions were implemented in the patient care setting to prevent nosocomial transmission. Contact tracing and evaluation of close and high-risk contacts with symptoms was conducted. Laboratory precautions included barrier precautions and diversion of specimens. Communication occurred to both hospital employees and the media.

Three high-risk contacts, 13 close contacts, and 60 casual contacts were identified. Two close contacts became symptomatic and required evaluation. Challenging process issues included tracing of laboratory specimens, decontamination of laboratory equipment, and internal and external communication. After 5 days, a transmissible VHF of public health consequence was ruled out in the index case.

Contingency plans for VHF can be implemented in an efficient and feasible manner. Contact tracing, laboratory issues, internal communication, and media interest can be anticipated to be the key challenges.

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.

Medline searches were conducted spanning 1966 to 2002. Pertinent abstracts of unpublished studies providing sufficient data were included.

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.

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.

To evaluate the impact of an interventional multidisciplinary antibiotic management program on expenditures for antibiotics and on the incidence of nosocomial infections caused by Clostridium difficile and antibiotic-resistant pathogens during 7 years.

Prospective study with comparison with preintervention trends.

University-affiliated teaching hospital.

All adult inpatients.

A multidisciplinary antibiotic management program to minimize the inappropriate use of third-generation cephalosporins was implemented in 1991. Its impact was evaluated prospectively. The incidence of nosocomial C. difficile and resistant Enterobacteriaceae infections as well as the rate of vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) were compared with those of National Nosocomial Infections Surveillance System hospitals of similar size.

Following implementation of the program, there was a 22% decrease in the use of parenteral broad-spectrum antibiotics (P < .0001) despite a 15% increase in acuity of patient care during the following 7 years. Concomitantly, there was a significant (P= .002) decrease in nosocomial infections caused by C. difficile and a significant (P = .02) decrease in nosocomial infections caused by resistant Enterobacteriaceae. The program also appeared to have a favorable impact on VRE rates without a sustained impact on MRSA rates.

These results suggest that an ongoing multidisciplinary antibiotic management program may have a sustained beneficial impact on both expenditures for antibiotics and the incidence of nosocomial infection by C. difficile and resistant bacterial pathogens.

To determine the costs of the interventions aimed at controlling the 4-month outbreak and to determine the attributable length of stay (LOS) associated with infection and colonization with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae.

A retrospective cost analysis was conducted from the hospital perspective. A micro-costing approach was employed. The LOS of four groups of hospitalized patients were compared with each other. National Perinatal Information Center criteria were used to stratify infants for severity of risk. The LOS of each group was compared with that of a national sample of similarly stratified infants.

A level III-IV, 45-bed neonatal intensive care unit.

Infant groups were infected (n = 8), colonized (n = 14), concurrent cohort (n = 54), and prior cohort (n = 486).

The cost of the outbreak totaled $341,751. The largest proportion of costs was related to healthcare worker time providing direct patient care (2,489 hours at a cost of $146,331). Infected and colonized neonates had longer LOS than either the concurrent cohort or the prior cohort (P < .001). Compared with the national sample, infected infants had a 48.5-day longer mean LOS (95% confidence interval [CI95], 1.7 to 95.2), whereas the prior cohort's mean LOS was 6 days shorter (CI95, -9.4 to -2.9).

This study increases the understanding of the burden of these multidrug-resistant organisms. Further research is needed to estimate the societal costs of these infections and the cost-effectiveness of preventive interventions.