Clinical Microbiology and Antimicrobial Chemotherapy. 2015; 17(3):227-234
To assess antimicrobial resistance of gram-negative microorganisms causing complicated intra-abdominal infections (IAI) in Russia.
This was a multicenter (a total of 21 cities), prospective, microbiological study to collect Gram-negative pathogens from patients with complicated IAI. Identification was performed using MALDITOF mass spectrometry. Minimal inhibitory concentrations (MICs) of antibiotics were determined by dilution method according to the current CLSI and EUCAST guidelines.
A total of 1908 isolates of gram-negative pathogens was obtained (357 isolates in community-acquired IAI, and 1551 isolates in nosocomial IAI). Enterobacteriaceae were the most common pathogens of IAI: 318 (89.1%) isolates in community-acquired IAI, and 821 (52.9%) isolates in nosocomial IAI. The remaining pathogens represented non-fermenting microorganisms (P. aeruginosa, A. baumannii). ESBL production was found in 45.4% of all Enterobacteriaceae, and the majority of them (92.6%) were nosocomial strains. ESBL production in community-acquired and nosocomial isolates was 11.9% and 58.3%, respectively. Carbapenems, irrespective of ESBL production or site of infection, exhibited highest activity against isolated microorganisms (susceptibility: 94.0% to 100%). Tigecycline resistance among community-acquired and nosocomial Enterobacteriaceae isolates was 0.6% and 10.2%, respectively. Resistance rates of community-acquired Enterobacteriaceae isolates to gentamicin, fluoroquinolones, III–IV generation cephalosporins, and penicillin/beta-lactamase inhibitor combinations were 18.2%, 18.2%, 16.4% and 28.1%, respectively. Resistance rates of the nosocomial pathogens to the listed above antimicrobials were 52.4%, 49.3%, 60.1% and 62.0%, respectively. Colistin was found to be the only active antibiotic against >90% of nosocomial isolates of P. aeruginosa and A. baumannii.
Taking into account high rates of ESBL production among Enterobacteriaceae, which are the main pathogens of complicated IAI, carbapenems should be considered as the most appropriate empiric treatment option for both community-acquired (in patients with risk factors for resistant pathogens), and nosocomial infections. Due to extremely high resistance of P. aeruginosa и A. baumannii, antimicrobial therapy of nosocomial IAI caused by these pathogens should be chosen based on the local susceptibility data.