Outbreak of severe Pseudomonas aeruginosa infections caused by a contaminated drain in a whirlpool bathtub.

During a 14-month period, 7 patients with hematological malignancies acquired serious infections caused by a single strain of multiply resistant Pseudomonas aeruginosa. A case-control study, culture surveys, and pulsed-field gel electrophoresis implicated a whirlpool bathtub on the unit as the reservoir. All case patients and 32% of control patients used this bathtub (P=.003). The epidemic strain was found only in cultures of samples taken from the bathtub. The drain of the whirlpool bathtub, which was contaminated with the epidemic strain, closed approximately 2.54 cm below the drain's strainer. Water from the faucet, which was not contaminated, became contaminated with P. aeruginosa from the drain when the tub was filled. The design of the drain allowed the epidemic strain to be transmitted to immunocompromised patients who used the whirlpool bathtub. Such tubs are used in many hospitals, and they may be an unrecognized source of nosocomial infections. This potential source of infection could be eliminated by using whirlpool bathtubs with drains that seal at the top.

Vancomycin-resistant Enterococcus faecium bacteremia: risk factors for infection.

We describe an outbreak of vancomycin-resistant Enterococcus faecium (vanA phenotype) bacteremia on the oncology ward of a tertiary care community hospital. In 10 of the 11 cases the patients had leukemia and were neutropenic (median duration of neutropenia, 21 days) at the time of bacteremia. On average, patients received six antibiotic agents for a total of 61 agent-days prior to development of vancomycin-resistant E. faecium bacteremia. The mortality rate was 73%. Molecular typing of 22 isolates revealed that the majority (83%) represented a common strain, indicating nosocomial spread. When the 11 cases were compared to 22 matched control patients, gastrointestinal colonization with vancomycin-resistant E. faecium (odds ratio [denominator, 0] infinity, P = .005) and the use of antimicrobial agents with significant activity against anaerobes (metronidazole, clindamycin, and imipenem; odds ratio infinity, P = .02) were found to be risk factors for the development of vancomycin-resistant E. faecium bacteremia. Since no proven therapy for such infection exists, there is an urgent need to identify effective measures to prevent and control the development of vancomycin-resistant E. faecium bacteremia.

Efficient detection and long-term persistence of the carriage of methicillin-resistant Staphylococcus aureus.

The natural history of the carriage of methicillin-resistant Staphylococcus aureus (MRSA) was examined in a 9-year retrospective cohort study of 102 known carriers. The populations studied consisted of patients admitted to a university hospital from 1989 through 1991; a review extending back to January 1983 was conducted. The focuses of the study included the duration of carriage among patients who were known to have carried MRSA previously and who were readmitted to the hospital (36 patients) and the optimal anatomic site for screening (66 patients). Cultures of the nares (sensitivity, 93%; negative predictive value, 95%) were considerably more valuable for the detection of MRSA colonization than were cultures of cutaneous sites of the axilla, groin, and perineum (sensitivity, < or = 39%; negative predictive value, < or = 69%). The estimated half-life of MRSA colonization in this special population of patients was approximately 40 months. Restriction enzyme analysis of plasmid types of paired isolates from the 12 patients with MRSA carriage persisting for > 12 months revealed five instances (42%) in which both isolates were of the same type. In summary, our results indicate that the majority of readmitted carriers harbor MRSA for > 3 years and that, in this population, culture of the anterior nares alone (with culture of wound or sputum, when present) is a valid and efficient method for the detection of persistent MRSA carriage.