Antimicrobial resistance of gram-negative pathogens isolated from hospitalized patients in Rostov region

Abstract

Objective. To evaluate resistance rates to carbapenems and III–IV generation cephalosporins among gramnegative bacteria, including production of carbapenemases and extended-spectrum beta-lactamases (ESBL). Materials and Methods. A total of 460 gram-negative bacteria isolated from hospitalized patients aged 1 to 85 years from 8 medical institutions of Rostov-on-Don and the region from April 2018 to December 2019 were tested by conventional microbiological methods. The most common acquired carbapenemases genes were determined by real-time PCR using commercial kits (Central Research Institute of Epidemiology, Russia). Results. The tested isolates included 180 (39.1%) isolates of K. pneumoniae, 87 (18.9%) – E. coli, 101 (22.0%) – A. baumannii and 92 (20.0%) – P. aeruginosa. K. pneumoniae and E. coli isolates exhibited the high resistance rates to cefotaxime – 96.7% and 71.2%, to ceftazidime – 95.5% and 54.0%, and to cefepime – 95.5% and 54.0%, respectively. ESBL production was detected in 35.0% and 78.2% of K. pneumoniae and E.coli isolates, respectively. K. pneumoniae and E. coli isolates were resistant to imipenem, meropenem, and ertapenem: 57.8% and 3.4%; 55.0% and 2.3%; 60.0% and 4.6%, respectively. Carbapenemase production was detected in 27.8% of K. pneumoniae and 4.6% of E. coli isolates. The most common beta-lactamases were metallo-beta-lactamases (NDM) and serine carbapenemases (OXA-48). A. baumannii isolates showed the high resistance rates to imipenem and meropenem (87.1% and 85.1%). The most common beta-lactamases were metallo-beta-lactamases (NDM) and serine carbapenemases (OXA-24/40 and OXA-23). P. aeruginosa isolates also showed the high resistance to carbapenems – imipenem (61.9%) and meropenem (58.7%). The most common betalactamases were metallo-beta-lactamases (VIM) and GES-5. Conclusions. The results of this microbiological study indicate the extremely high prevalence of aerobic gram-negative bacteria in different infections. A. baumannii, P. aeruginosa, K. pneumoniae and E. coli isolates being resistant to third- and fourth-generation cephalosporins and carbapenems are particularly dangerous, especially due to production of ESBL and carbapenemases. The most clinically important are OXA and NDM beta-lactamases.

Keywords

• antimicrobial resistance
• gram-negative bacteria
• beta-lactams
• carbapenemases
• metallo-betalactamases