ANTIBIOTIC SUSCEPTIBILITY IN THE SURGICAL INTENSIVE-CARE UNIT COMPARED WITH THE HOSPITAL-WIDE ANTIBIOGRAM

Objective: To compare the antibiotic susceptibility of bacterial isola tes from patients in the sugical intensive care unit (SICU) with hospi tal-wide bacterial susceptibility. Design: Retrospective cohort analyt ic study. Setting: Eight-bed SICU in a university-affiliated teaching hospital. Patients: All hospitalized patients with culture results pos itive for microorganisms. Interventions: None. Main Outcome Measures: Antibiotic susceptibility data were collected retrospectively for all bacterial isolates from SICU patients during July 1, 1994, to June 30, 1995. All duplicate and surveillance cultures were eliminated from th e data set. Susceptibility testing was conducted using our standard la boratory methods. Results were compared with the hospital-wide antibio gram (HWA) for the same time period. Comparisons were made using the c hi(2) test with Yates correction or the Fisher exact test, as appropri ate; Staphylococcus aureus (HWA, n=494; SICU, n=71) was significantly less susceptible to oxacillin (51% vs 28%; P < .001), ciprofloxacin (5 0% vs 25%; P < .001), erythromycin (46% vs 23%, P < .001), and clindam ycin (51% vs 27%; P < .001) in the SICU, Coagulase-negative staphyloco cci (HWA, n=339; SICU, n=37) were significantly less susceptible to ox acillin (33% vs 16%; P=.04) and clindamycin (57% vs 34%; P=.02). Pseud omonas aeruginosa (HWA, n=513; SICU, n=96) was less susceptible to imi penem (85% vs 74%, P=.01) and more susceptible to ticarcillin-clavulan ic acid (88% vs 100%, P<.001) in the SICU. Escherichia coli (HWA, n=47 4; SICU, n=36) was more susceptible to most penicillin-derivative anti biotics in the SICU (ampicillin [68% vs 83%, P=.06], ticarcillin [65% vs 86%, P=.01], mezlocillin [76% vs 95%, P=.01], and ticarcillin-clavu lanic acid [88% vs 100%, P=.02]). Conclusions: The 2 most commonly iso lated bacterial pathogens in the SICU (S aureus and P aeruginosa) had significantly different susceptibility patterns compared with the HWA. Surprisingly, E coli isolated in the SICU tended to be more susceptib le to penicillin-derivative antibiotics. These data indicate that empi ric antibiotic choices in the SICU may be better guided by unit-specif ic antibiograms.