Virginia D. Wells, MD; Edward S. Wong, MD; Barbara E. Murray, MD; Philip E. Coudron, PhD; Denise S. Williams, MT; Sheldon M. Markowitz, MD
▪ Objective: To investigate the risk factors, clinical features, molecular epidemiology, and treatment outcomes associated with an outbreak of infections due to beta-lactamase-producing, high-level gentamicin-resistant Enterococcus faecalis.
▪ Design: Case-control and molecular genetics study.
▪ Setting: Tertiary care Veterans Affairs hospital.
▪ Patients: Sixty-five patients infected or colonized with beta-lactamase-producing high-level gentamicin-resistant E. faecalis (case patients) were matched and compared with 65 randomly selected patients infected or colonized with beta-lactamase-negative, gentamicin-susceptible E. faecalis.
▪ Measurements and Main Results: During the 20-month study period, 124 of 1506 isolates (8.2%) of E. faecalis from 70 patients were found to produce beta-lactamase. Univariate analysis showed older age, higher APACHE II score, nosocomial acquisition, recent surgical procedure, total parenteral nutrition, and antibiotic treatment to be significantly associated with the acquisition of beta-lactamase-producing, high-level gentamicin-resistant E. faecalis. A multivariate analysis, done using stepwise multiple logistic regressions, showed that only two variables remained significant: an APACHE II score > 6 (odds ratio, 9.5; 95% Cl, 4.4 to 20.3) and antibiotic treatment (odds ratio, 10.2; Cl, 4.5 to 23.2). The mortality rate for case patients was 7.7% (5 of 65 patients; Cl, 1.2% to 14.2%); no control patient died. Of 23 infections occurring in case patients, 13 were treated with "inappropriate" antibiotics (regimens that included a beta-lactamase-unstable antibiotic); 2 patients improved and 11 had complete resolution of disease. "Appropriate" treatments (regimens that included a beta-lactamase-stable antibiotic) were used in 10 patients; 5 of 10 infections were fatal. Restriction enzyme digests of total chromosomal DNA showed nearly identical patterns for selected isolates of beta-lactamase-producing, high-level gentamicin-resistant E. faecalis, suggesting dissemination through the hospital of a single strain of E. faecalis.
▪ Conclusions: Fatal infections were observed despite treatment with beta-lactamase-stable antibiotics. The risk for infection or colonization with beta-lactamase-producing, high-level gentamicin-resistant E. faecalis was strongly associated with severe underlying disease (acute physiology and chronic health evaluation [APACHE] II score, > 6) and previous antibiotic treatment. These results may be useful in targeting high-risk patients for infection-control interventions.
Wells VD, Wong ES, Murray BE, et al. Infections Due to Beta-Lactamase-producing, High-Level Gentamicin-resistant Enterococcus faecalis. Ann Intern Med. 1992;116:285–292. doi: 10.7326/0003-4819-116-4-285
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Published: Ann Intern Med. 1992;116(4):285-292.
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