Molecular characterization of Klebsiella pneumoniae isolates from stool specimens of outpatients in sentinel hospitals Beijing, China, 2010–2015

BACKGROUND Klebsiella pneumoniae (K. pneumoniae) is an opportunistic pathogen associated with community-acquired infections and nosocomial infections. From 2010 to 2015, K. pneumoniae testing was included into the exiting diarrhea-syndrome surveillance with objective to estimate the prevalence of K. pneumoniae in diarrhea-syndrome patients, test antibiotics susceptibility and investigate molecular characteristics. METHODS Stool specimens from diarrhea-syndrome outpatients were cultured and identified the pathogens by the Vitek2 Compact instrument. The isolated K. pneumoniae strains were tested for antibiotics susceptibility by minimal inhibitory concentration (MIC) method, and subtyped by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). RESULTS 22 K. pneumoniae strains were identified from 4340 stool specimens of outpatients who visited sentinel hospitals in Beijing during 2010-2015. All strains were sensitive to gentamicin, nalidixic acid, ciprofloxacin, ceftriaxone, cefotaxime, cefepime, imipenem. The highest resistance rate of K. pneumoniae strains was 100% to amoxicillin-clavulanate, followed by 72.7% to ampicillin. These 22 K. pneumoniae strains were characterized into 21 different PFGE types and 20 MLST types with less similarity. CONCLUSIONS The detection rate of K. pneumoniae in stool specimens from outpatients with diarrhea syndromes was about 0.5% in Beijing. Less similarity of the isolated strains indicated the unlikely long-term circulating of K. pneumoniae in the community. ST23 was the most common genotype. Drug resistance of the community-acquired K. pneumoniae was not a serious problem in comparing with hospital-acquired infections. High vigilance in the community-acquired K. pneumoniae strains and investigation of pathogens' microbiological characteristics are valuable for signals detection for drug resistance in population and strains variation.