Journal Reviews

Lai KK, Kelly AL, Melvin ZS, et al. Failure to eradicate vancomycin-resistant enterococci in a University hospital and the cost of barrier precautions. Infect Control Hosp Epidemiol 1998; 19:647-652.

Despite considerable effort and expense, the presence of vancomycin-resistant enterococci (VRE) could not be eradicated in a tertiary care teaching hospital, the authors report.

"VRE poses serious therapeutic problems, and, once it has spread beyond a geographically isolated group of patients, eradication becomes difficult, labor intensive, and expensive," they found. "Control of VRE may require the cooperation of an interdisciplinary group to improve continual compliance with good infection control practices."

Infection control interventions included placement of patients with VRE in private rooms; use of strict contact isolation; cohorting of patients and nursing staff; and prohibiting of equipment sharing. Researchers monitored compliance with a vancomycin restriction policy and hand washing, and assessed the adequacy of environmental cleaning. The interventions decreased the number of new cases of VRE, but total eradication of VRE was not achieved. Compliance with the room-cleaning protocol was 91% (141/155 observations). Overall, hand washing compliance was 71%, but was only 51% following interactions with patients who were not under isolation.

"Poor hand washing practices, environmental contamination, and sharing of equipment all played a role," they note. "Hand washing compliance among health care personnel after contact with patients not in isolation was poor. Because approximately 40% of VRE-colonized patients were discovered by rectal-culture surveillance, these patients could have acted as a reservoir for transmission of VRE before their cultures were known to be positive."

An interdisciplinary group of clinicians worked to enforce good hand washing, improve environmental cleaning, discontinue sharing of equipment, and improve the appropriate use of vancomycin. Following these efforts, the number of new VRE cases was decreased from five a month to three.

"Controlling a VRE epidemic can be costly," the authors conclude. "Extra expenses for gloves and gowns alone exceeded $11,000 a year after the epidemic began. Our estimate of the cost of isolation did not include the need for private rooms, cost due to extended length of stay secondary to VRE acquisition, special housekeeping procedures, extra equipment for designated use, treatment of VRE infection, surveillance of colonized patients, and the hidden social costs of patient isolation and the emotional impact on family members."

Still, colonization with VRE predisposes patients to VRE infections, including bacteremia, the authors note, citing another study that found that a mean duration of hospitalization for patients with nosocomial enterococcal bacteremia was 83 days compared to 44 days for matched control.

"The cost savings in the prevention of an episode of VRE bacteremia makes the $10,000 in extra expense in barrier precautions seem insignificant," the authors emphasize.

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Villers D, Espaze E, Coste-Burel M, et al. Nosocomial Acinetobacter baumannii infections: Microbiological and clinical epidemiology. Ann Intern Med 1998; 129:182-189.

In the past decade, Acinetobacter baumannii has emerged as an important nosocomial pathogen that is often resistant to numerous antimicrobial agents and can cause life-threatening infections in patients with altered host-defense mechanisms. In addition, it has a tendency toward cross-transmission, especially in intensive care units, where numerous outbreaks have occurred.

To study the epidemiology of A. baumannii infections and assess the relation between fluoroquinolone use and the persistence of multidrug-resistant clones, the authors conducted three case-control studies and a retrospective cohort study in a 20-bed medical and surgical intensive care unit.

A. baumannii was isolated from 45 patients in urine (31%), the lower respiratory tract (26.7%), wounds (17.8%), blood (11.1%), skin (6.7%), cerebrospinal fluid (4.4%), and sinus specimens (2.2%). One death was due to A. baumannii infection. Antimicrobial resistance pattern and molecular typing were used to characterize isolates. The incidence of A. baumannii infection and the use of fluoroquinolones were calculated annually. Initially, 28 patients developed A. baumannii infection. Eleven isolates had the same antimicrobial susceptibility profile, genotypic profile, or both (epidemic cases), and 17 were heterogeneous (endemic cases).

A surgical procedure done in an emergency operating room was the main risk factor for epidemic cases, whereas previous receipt of a fluoroquinolone was the only risk factor for endemic cases. The opening of a new operating room combined with the restriction of fluoroquinolone use contributed to a transitory reduction in the incidence of infection. The disappearance of the epidemic strain from the ICU after the original operating room was closed suggests that the room may have been the primary reservoir for the epidemic strain, which in turn led to secondary transmission in the ICU, the authors note.

"Our study showed that previous receipt of a fluoroquinolone was an independent risk factor for endemic A. baumannii infection and that the selection pressure caused by the indiscriminate use of fluoroquinolones was responsible for the persistence of multidrug-resistant clones over at least five years," they concluded. "The parallelism between the amount of fluoroquinolones prescribed and the number of cases of A. baumannii infection clearly shows a dose-response gradient: the greater the consumption of fluoroquinolones, the stronger the selection pressure."

A companion editorial in the same issue (Jarvis WR, McDonald LC. Linking antimicrobial use to nosocomial infections: The role of a combined laboratory-epidemiology approach. Ann Intern Med 1998; 129:245-246) credits the study for showing the value of combining laboratory and epidemiologic investigations to address the complex challenges of antibiotic resistance in a changing health care system.

"Meeting the challenge to investigate and understand increasingly complex nosocomial infections, however, will require increased collaboration among all members of the investigation team," the editorial notes. "Their report serves as an excellent example of what may be achieved when the disciplines of clinical medicine, laboratory investigation, and hospital epidemiology are fully integrated in the investigation of nosocomial outbreaks."