Genotyping, antibiotic resistance and biofilm formation of Stenotrophomonas maltophilia clinical isolates from Serbia

Abstract

Stenotrophomonas maltophilia is an environmental bacterium and an opportunistic pathogen usually associated with healthcare-associated infections, which has recently been recognized as a global multidrug resistant organism. The aim of this study was genotyping and physiological characterization of S. maltophilia collected during the routine health care at The Institute for Mother and Child Health Care of Serbia “Dr Vukan Čupić“. It is the large, tertiary care pediatric hospital in Belgrade, Serbia, hosting the national reference cystic fibrosis (CF) center for pediatric and adult patients. We characterized 88 S. maltophilia strains, 42 strains of cystic fibrosis (CF) and 46 strains of non-cystic fibrosis (non-CF) origin isolated from 2013 to 2015 in order to investigate their genetic relatedness and phenotypic traits. Genotyping was performed using sequencing of 16S rRNA gene, Pulse Field Gel Electrophoresis (PFGE) and Multi locus sequencing typing (MLST) analysis. Sensitivity to five relevant antimicrobial agents was determined, namely trimethoprim/sulfamethoxazole (TMP/SMX), chloramphenicol, ciprofloxacin, levofloxacin and tetracycline. Surface characteristics, motility, biofilm formation and adhesion to mucin were tested in all strains. In addition, influence of different factors (temperature, pH, agitation and CO2) on biofilm formation, kinetics of selected biofilm producers and effect of TMP/SMX on formed biofilm were analyzed. Statistical approach was used to determine correlations between obtained results. All analyzed clinical isolates belong to S. maltophilia species with identity ranging from 95% to 99% with S. maltophilia strains from the NCBI database what was confirmed by sequencing of PCR products of amplified 16S rRNA gene...