Risk Factors for Intestinal Carriage of Pseudomonas aeruginosa on Admission to a Medical Service.
Background: Intestinal carriage is a reservoir for invasive infection with Pseudomonas aeruginosa (PA) and for its dissemination. The prevalence of colonization of healthy persons outside of or on entry to hospitals is generally low. Screening for intestinal carriage of PA on admission to a medical service was conducted in order to better understand the epidemiology of PA, to define risk factors for intestinal colonization and to help design infection control measures. Methods: Patients were screened on admission (convenience sample). Rectal swabs were cultured into enrichment broth, and after overnight incubation plated onto MacConkey agar containing 2µg/ml amphotericin B and 1µg/ml ceftriaxone. Bacteria growing after 48 h were identified to species level using the Vitek 2 system. Univariate and multivariate analyses were performed. Results: 135 patients were screened (52% males, median age 78 y). PA was isolated from 43 patients (carrier rate 31.8%). Variables associated with PA carriage by univariate analysis were: ischemic heart disease (OR 3.1, p = 0.002), nursing home residence (OR 3.6, p = 0.008) and bladder catheter (OR 3.3, p = 0.03). Recent hospital discharge and antibiotic treatment were not significantly associated with carriage of PA. In multivariate analysis, ischemic heart disease (OR 3.2, 95% CI 1.4-6.9, p = 0.003) and nursing home residence (OR 3.6, 95% CI 1.2-10.3, p = 0.01) were independently associated with carriage of PA. Conclusions: PA carriage rate on admission to our medical service is high. The strong association between ischemic heart disease and intestinal colonization by PA has not been previously described; Possible modulation of mucosal resistance to colonization by drugs such as salicylic acid requires further investigation.
Full conference title:
43rd Interscience Conference on Antimicrobial Agents