Characteristics and properties of Serratia marcescens isolated in bacteremia in children

Introduction. Serratia marcescens is an opportunistic gram-negative microorganism, currently has been detected with increasing frequency in various clinical biomaterials from sick persons is the causative agent of nosocomial infections. The aim of the work is to determine microbiological and clinical features of S. marcescens in bloodstream infections in children. Materials and methods. Nineteen isolates of S. marcescens were isolated from blood cultures. Antibiotic sensitivity was determined by broth microdilution method. Carbapenemase gene were determined using real-time polymerase chain reaction. Biofilm formation was studied on abiotic surfaces using polystyreneplates. Population diversity was determined by multilocus genotypic analysis. Results. Carbapenems, fosfomycin and biseptol showed the highest antimicrobial activity in vitro. Resistance to aminoglycosides, aztreonam, cefepime, and ticarcillin/clavulanate was over 50%. According to PCR data, only OXA-48 carbapenemases were found in 11% of isolates, NDM — in 5%, and a combination of carbapenemases — in 15%. Biofilms of moderate intensity were formed in 13 (68%) isolates, and weak biofilms — in 6 (32%). According to the genotypic analysis, a large proportion of isolates with multiple resistance were included in one group. All of them were singled out over one year from one department — perhaps there was a single source. In 3 cases, patients were diagnosed with sepsis, 1 of them had an unfavourable outcome. Bacteremia occurred on the 3rd day after the initial isolation of S. marcescens. An unfavourable outcome occurred on the 10th day of bacteremia. S. marcescens in this case had multiple resistance and a combination of resistance genes, also belonged to genotypic group I, which is often found in our work. Conclusion. S. marcescens in bloodstream infections is a serious problem for pediatric patients. Natural resistance to polymyxins, as well as acquired resistance to carbapenems and aminoglycosides, cause particular alertness and attention to this microbial agent.