Utility of serial rectal swab cultures for detection of ceftazidime- and imipenem-resistant gram-negative bacili from patients in the intensive care unit

Forty-four patients receiving intensive care were studied prospectively to assess the utility of serial rectal swab cultures and clinical correlates o f resistance for Pseudomonas aeruginosa, Enterobacter spp., Citrobacter spp ., Morganella morganii, and Serratia marcescens strains resistant to ceftaz idime or imipenem. Strains of Pseudomonas aeruginosa, Enterobacter spp., Ci trobacter spp., or Morganella morganii were found in 26 of 44 (59%) patient s: 17 (65%) in clinical sites (11 with concomitant rectal isolates) and nin e (35%) in a rectal site only. Of 49 total isolates, 13 (26.5%) were resist ant: 10 (20.4%) to ceftazidime and three (6.1%) to imipenem. Surveillance r ectal swabs from 27 patients without a clinical isolate identified two pati ents with resistant organisms (15% of all resistant isolates). The majority of resistance to ceftazidime or imipenem among Pseudomonas or Enterobacter can be detected by the use of clinical specimens alone.