Objective Using molecular typing of S.aureus (SAUR) and E.cloacae (ECLO), prospectively evaluate nosocomial bacterial pathogen source and spread in a population-based study of ICU patients. Methods: From 4/1/96 to 9/30/96, tracheal aspirates (TASP) from intubated ICU patients at SFGH were cultured at admission and regularly until extubation. All infecting/ colonizing isolates of SAUR and ECLO were also obtained from all ICU patients during the same time interval. SAUR isolates were genetically fingerprinted using PFGE of chromosomal ONA after restriction digest with Sma I; ECLO were similarly fingerprinted using Xba I. Results: 279 of 486 (57.4%) ICU patients were intubated. 94 patients had a TASP culture within 48 hrs of admission. 25 (26.5%) had SAUR in TASP at admission (index isolates); 23 SAUR index isolates were typed and 20 clones were found (3 were found twice). Of 18 patients with SAUR clinical isolates, 4 had SAUR identical to an index isolate. 3/25 patients with SAUR in TASP at admission developed SAUR infection with the same fingerprint (1 bacteremia/pnuemonia, 2 pneumonia). 8 patients acquired TASP SAUR colonization (not disease) in the ICU; 1 with an isolate identical to an index isolate. ECLO was isolated in TASP from 4 patients at admission; 13 patients acquired TASP ECLO (2 with identical strains that did not match the 4 index isolates). 5/17 (29%) patients with TASP ECLO developed nosocomial pneumonia most likely attributed to ECLO. Conclusions: Intubated ICU patients were often colonized with SAUR at admission and may be sources of person-to-person SAUR spread (5/23 typed index strains were later isolated from 1 or more ICU patients). SAUR disease was associated with colonization at admission but not later acquisition. Unlike SAUR, TASP ECLO was usually acquired after admission, acquisition was associated with infection, and did not appear to be readily transmitted person-to-person suggesting endogenous flora. Compared to antibiograms, molecular typing was useful in identifying otherwise occult person-to-person spread of pathogens in this ICU.
|Original language||English (US)|
|Number of pages||1|
|Journal||Clinical Infectious Diseases|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Microbiology (medical)
- Infectious Diseases