Pediatric bacteremia and CNS infections associated with <i>klebsiella pneumoniae</i>: molecular genetic characteristics and clinical features

Abstract

Klebsiella pneumoniae is one of the most significant and life-threatening pathogen of nosocomial infections. This opportunistic microorganism can cause infections of the bloodstream, respiratory tract, urinary tract, skin and soft tissues, inflammation of meninges of the brain and spinal cord, leading to elevated hospital mortality. The purpose of our study was a retrospective analysis of molecular genetic characteristics of K. pneumoniae isolated from blood and liquor samples as well as to describe clinical features in bacteremia and CNS infections. According to the results of assessed clinical data, K. pneumoniae isolates were selected from 64 children suffered from surgical pathology (congenital heart defects — 30%, abdominal pathology — 39%, severe combined trauma — 12%) and somatic diseases accompanied by antibacterial and/or glucocorticosteroid therapy — 14%. The minimum suppressive concentrations of antibiotics were determined by the broth micro-dilution method. Carbapenemases were detected by real time polymerase chain reaction. Virulence genes and capsule serotypes K1/K2 were assessed by multiplex PCR. Biofilms were grown using flat-bottomed polystyrene plates, followed by coloring, fixation, elution and data detection. The population diversity was assessed by multilocus sequence typing. Bacteremia and CNS infections associated with K. pneumoniae were fatal in 25% of cases. A substantial portion of the isolates demonstrated the phenotype of extremely drug resistance (XDR) — 43%, the phenotype of multidrug resistance (MDR) was shown in 16% of the isolates. The blaCTX-M cephalosporinase gene was found in 85% of the strains. The main determinant of resistance to carbapenems was the blaOXA-48 gene (33%); the blaNDM gene was detected in 9% of strains. The combination of blaOXA-48 and blaNDM was found in 7% of isolates. The study of biofilm production showed that moderate ability to form biofilms was shown in 61%, strong — 21%, and weak — 15% isolates. Two isolates (3%) did not form biofilms. The virulence genes entB and mrkD were detected in 100% of isolates, ybtS — in 78%. The iutA gene was found in 18% of the strains. Two isolates showed the presence of the kfu gene. Seven isolates belonged to the K2 serotype. 27 different genotypes were found in K. pneumoniae isolates examined. The most common were: ST307 — 21%, ST395 — 12%, ST48 — 7%, ST39 — 6% and ST29 — 6%. Infections of the bloodstream and central nervous system associated with K. pneumoniae have great importance in clinical practice. This microorganism is able to long persist on biotic and abiotic surfaces, has a wide natural and acquired resistance to antibiotics.