Usage of carbapenems significantly increase the rate of new colonisation due to antibiotic-resistant bacteria in hospitalised patients

Abstract number: O395

Tacconelli E., De Angelis G., Cataldo M., Mantengoli E., Spanu T., Pan A., Corti G., Radice A., Antinori S., Paradisi F., Carosi G., Antonelli M., Rossolini G., Cauda R.

Objectives: Accurate assessment of risk factors for colonisation with antibiotic resistant bacteria (ARB) is often confounded by scanty data on antibiotics use. The aims of the study were: to prospectively define the incidence of new colonisation due to ARB per 1,000 days of antibiotics; to determine mean time of acquisition; to measure patients'risk factors for acquiring ARB; and to compare genotypic patterns of the strains.

Methods: A 12-month prospective multicentre cohort study including all in-patients (pts) starting antibiotics was planned. Samples of nose and rectum were taken before and after starting antibiotics (day 2, 4, 7, 15, and 30). ARB included: meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and ciprofloxacin-resistant Pseudomonas aeruginosa (CR-PA). Pulsed-field gel electrophoresis was done to define genetic relatedness of the strains.

Results: In total, 6245 swabs from 864 pts were processed. The overall carriage rate of newly acquired ARB was 5%. The mean duration (days±standard deviation) of antibiotic therapy prior to the detection of a new colonisation was 8 (±4) for MRSA (range, 2–16), 6 (±6) for VRE (range, 2–19) and 9 (±8) for CR-PA (range, 2–28). The incidence of ARB per 1,000 days of therapy was 14 for carbapenems, 9 for glycopeptides, and 6 for cephalosporins of 3rd gen. and quinolones. Highest rates were observed for carbapenems in dialysed (29) and diabetic (28) pts and for 3rd gen. cephalosporins in pts with cronic renal impairment (27). Specific rates for MRSA were 8.2 per 1,000 days of macrolides, 7.9 of carbapenems, 3.2 of glycopeptides and 2.4 of cephalosporins. In the multivariate analysis length of hospitalisation >16 days (odds ratio [OR] 2.5, 95% confidence interval [CI] 1.2–5.1), HIV infection (OR 2.1, 95% CI 1.1–4.4), use of carbapenems (OR 2, 95% CI 1–3.8), and age >70 (OR 1.5, 95% CI 1.1–2) were significant predictors for new ARB acquisition (P < 0.05). All strains were genetically unrelated except for serial isolates from single patient.

Conclusions: The risk of ARB colonisation deeply varies during exposure to different antibiotics and is mainly related to pts underlying conditions and length of hospitalisation. Periodic screening of high risk pts undergoing antibiotics, in particular carbapenems, might be suggested.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
Back to top