High-level aminoglycoside-resistant enterococci. Colonization of nursing home and acute care hospital patients.

Enterococci with high-level resistance (HLR) to gentamicin sulfate and other aminoglycosides have emerged as pathogens in recent years. More than half of all current isolates of enterococci at the Ann Arbor (Mich) Veterans Administration (VA) Medical Center are HLR strains. We determined the rate of colonization with HLR enterococci in patients in the acute care hospital, the attached nursing home, and a private nursing home. We also studied the factors related to colonization and the molecular relatedness of strains of HLR enterococci in these settings. In the VA facilities, 47.4% of patients in the nursing home and 36.1% of patients in the acute care hospital were colonized, compared with a 4.3% colonization rate in the private nursing home. Intravenous or Foley catheters and bedridden status were associated with colonization in the acute care setting; the need for advanced nursing care and prior antibiotic therapy were associated with colonization in the nursing home. Environmental surfaces were contaminated with HLR enterococci in both VA settings. Plasmid analysis of HLR strains revealed identity between both patient and environmental strains in the nursing home care unit and the acute care hospital. Nursing home patients, with their high rate of colonization with HLR enterococci and their frequent movement into the acute care hospital, may play a role as a reservoir for subsequent transmission of HLR enterococci.

Nosocomial infection by gentamicin-resistant Streptococcus faecalis. An epidemiologic study.

Enterococci with high-level resistance to gentamicin account for 55% of clinical isolates of enterococci found in patients at the Ann Arbor Veterans Administration Medical Center. We prospectively studied cultures obtained from all 100 patients hospitalized from 1 December 1985 through 23 January 1986 on the surgical and thoracic intensive care units and a general medical floor. Ten patients' cultures grew colonies of gentamicin-resistant enterococci--six after admission to the intensive care units and four after hospitalization on the medical ward. The initial sites of colonization were the rectal and perineal areas in seven patients, sternal wound in one, urine in one, and the rectal and perineal areas as well as urine after Foley catheter insertion in one. Nine patients died and three of the deaths were associated with enterococcal infection. The acquisition of resistant strains was associated with previous and more frequent exposure to antimicrobial agents, and with geographic clustering of patients. Resistant enterococci were isolated from the hands of hospital personnel and were frequently isolated from environmental surfaces. Nosocomial acquisition and interhospital spread of gentamicin-resistant enterococci was shown to have occurred when plasmid content was used as an epidemiologic marker.