Epidemiology of infections caused by multidrug-resistant gram-negative bacteria in adult hospitalized patients at Siriraj Hospital.

OBJECTIVE: To investigate the clinical characteristics, risk factors, outcomes, antibiotic treatment and complications of hospitalized patients infected with multi-drug resistant (MDR) gram-negative bacteria in Siriraj Hospital.

MATERIAL AND METHOD: A cross sectional study was performed in all hospitalized patients at Siriraj Hospital who had positive culture for Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii during February to May 2012. Clinical characteristics, risk factors and outcomes of MDR gram-negative bacteria were analyzed.

RESULTS: The prevalence of overall MDR gram-negative bacteria was 48.8%. The percentage of MDR organism was 37.8% for Extended Spectrum Beta Lactamase (ESBL)-producing Enterobactericeae, 39.3% for carbapenem-resistant P. aeruginosa and 88.7% for MDR A. baumannii. Infections caused by MDR organisms were associated with admission to medical wards, respiratory tract origin and hospital onset of infection. The significant risk factor of overall MDR organism infection was previous antibiotic use within 1 year (adjusted odd ratio 6.818, 95% CI = 1.337-34.770). Rate of inappropriate antibiotic use was 56.7% for initial empirical regimen and under treatment was significantly higher in MDR group. The 30-day and 90-day survival rates of MDR group were significant lower than non-MDR group (58.8% vs. 75.0%, p = 0.013 at 30th day and 43% vs. 63%, p = 0.012 at 90th day). Antibiotic associated adverse effect found 42.9% in MDR group and 20.0% in non-MDR group (p < 0.001).

CONCLUSION: The strongest risk factor for acquiring MDR gram-negative infection was previous antibiotic use. Inadequate empirical antimicrobial treatment was common in patients infected with MDR pathogens, resulting in unfavorable outcome and mortality.