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

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

Genomic features of resistant <i>Klebsiella pneumonia</i>, isolated from the bloodstream and cerebrospinal fluid of pediatric hospital patients

Introduction. Carbapenemase-producing Klebsiella pneumoniae (CP-Kp), which are international high-risk clones, have become a problem of utmost importance. CP-Kps, adapting to the hospital environment, evolve into convergent pathotypes. Such variants combine traits of two genetic lineages: multidrug resistant (MDR) and hypervirulent. The pathotypes, along with MDR K. pneumoniae, pose an exceptional threat to young patients during systemic infection. The objective of this study is the detailed molecular genetic analysis of MDR isolates of K. pneumoniae detected during the monitoring of resistant Gram-negative bacteria at the National Medical Research Center for Children’s Health in 2014–2021. Materials and methods. Whole-genome sequencing with a subsequent bioinformatics analysis of eight MDR isolates from the bloodstream and cerebrospinal fluid. Results. MDR isolates belonged to 4 sublineages (SL): SL307, SL395, SL29 and SL1198. In the genomes of 6 pangrug-resistant (PDR) isolates, genes associated with resistance to all categories of antibiotics recommended for Enterobacteriaceae therapy were identified. Plasmids were present in all genomes. In 6 isolates, plasmids contained heavy metal ion resistance operons in addition to antibiotic resistance genes. Prophages within the plasmids were also involved in the transfer of resistance genes. The ST395 isolate from the cerebrospinal fluid belonged to the convergent pathotype in terms of resistance and virulence. Comparison of genomes within SLs revealed recombination events in the K- and O-locus regions and the Yersiniabactin operon. Conclusion. Thus, in a sample of resistant K. pneumoniae isolated from bloodstream and cerebrospinal fluid, 6 PDR isolates were detected, one of which belongs to the convergent pathotype ST395