Klebsiella pneumoniae (KP) represents one of the main causative agents of opportunistic infections. KP associated infectious diseases can be local, for example, pneumonia, and generalized, including severe, often life-threatening conditions (meningitis, sepsis). Besides the chromosomal genome with a variety of different genetic loci, KP contains an additional plasmid genome which endues it with important biological properties. That’s why KP strains can be opportunistic, hypervirulent, and resistant to antimicrobials. In this literature review, literature data on the molecular resistant mechanisms, virulence factors and infectious diseases caused by KP is discussed.

Objective - assessment of RT-PCR for the detection of carbapenem-resistance genes in gram-negative bacteria. A total, 499 strains of gram-negative microorganisms isolated in two pediatric hospitals in 2019-2020 were studied. Species identification was performed using MALDI-ToF mass-spectrometry (Bruker Daltonics, Germany). Meropenem and imipenem minimal inhibitory concentration (MIC) was determined by E-test method (BioMerieux, France). The presence of acquired carbapenemase genes of IMP, NDM, VIM, KPC, OXA-48, OXA-23, OXA-40, OXA-58-groups was determined by RT-PCR. Klebsiella pneumoniae (34%), Escherichia coli (4%), Serratia marcescens (6%) and other members of Enterobacterales (6%), also gram-negative non-glucose-fermenting bacteria Acinetobacter baumannii (14%), Pseudomonas aeruginosa (36%) were found among selected strains. Carbapenemase production was found in 385 isolates (77%). The main mechanism determining carbapenem resistance in P. aeruginosa was the production of blaVIM (100%). A. baumanii strains harbored OXA-23 (55%) and OXA-40 (45%) carbapenemases. The major determinant of carbapenem resistance in K. pneumoniae isolates was OXA-48 carbapenemase, detected in 63% strains, 13% of the strains possessed blaNDM-group, 16% isolates had a combination of blaNDM-group and blaOXA-48-like. Carbapenemase of KPC-group was found in 8% K. pneumoniae strains. OXA-48 carbapenemase prevailed (95%) among S. marcescens strains. Most of E. coli isolates harbored metallo-beta-lactamase NDM (89%). Other members of Enterobacterales most often had OXA-48 carbapenemase (57%), 39% of the isolates carried blaNDM-group. In one strain, a combination of blaNDM-group and blaOXA-48-like was discovered. RT-PCR is a fast and reliable method for the detection of acquired carbapenemases and can be recommended for routine use in bacteriological laboratories.

Introduction. Infections of the bloodstream and central nervous system (CNS) caused by Pseudomonas aeruginosa are associated with a serious patient conditions and are often accompanied by high mortality.Aim. Molecular genetic characterization of P. aeruginosa isolated from positive samples of blood cultures and cerebrospinal fluid of patients under 18 years of age from intensive care units of hospitals.Materials and methods. We conducted a retrospective study of bacteremia and CNS infection cases associated with P. aeruginosa from 2014 to 2021. 24 clinical isolates of P. aeruginosa from positive blood cultures and CSF were analyzed. MICs of antibiotics were determined by serial microdilution in broth. Identification of the genes of carbapenemase was carried out using real-time PCR. Virulence genes were determined by PCR. Population diversity was assessed by MLST.Results. More than 70% of isolates showed resistance to carbapenem antibiotics. The phenotype of multiple drug resistance had 25% of the isolates. Extreme resistance was shown by 54% of isolates. The detection rate of metallo-β-lactamases (MBL) was 54%. Based on PCR data, 33% of the strains were found to have the ExoU type, and 67% had the ExoS type. According to MLST, 16 genotypes were identified. The structure was dominated by two sequence types ST654 (29%) and ST235 (12.5%). The structure of patients was dominated by children with surgical pathology — 16 cases, and there were eight somatic patients. Fatal outcome was observed in 28% of cases with bacteremia and CNS infection associated with P. aeruginosa.Conclusion. P. aeruginosa isolates from positive blood cultures and CSF samples are highly resistant to antibiotics; virulence genes were found in all isolates. Strains of high epidemic risk prevailed in the studied sample. More than a quarter of the described clinical cases had an unfavorable outcome.

Urinary tract infections are the second most common infections in children with spreading of antimicrobial resistance among uropathogens currently poses a high epidemiological threat.Purpose. Analysis of species prevalence and the presence of genetic determinants of antibiotic resistance.Materials and methods. In the study 215 midstream urine samples were retrospectively analyzed. Samples were obtained during 2017 and 2019 from patients aged 4 weeks to 17 years at the National Medical Research Center for Children's Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation.Results. Species of pathogen were identified in 93 samples, while the bacterial composition of other samples was classified as «intestinal flora» (n = 17), «coccus flora» (n = 16) or «mixed flora» (n = 89). The most common types of uropathogens in monopathogenic infections in 2017 and 2019 were Escherichia coli (37.5% and 29.2%, respectively). Among infections caused by multiple pathogens, the most common etiological agents were Pseudomonas aeruginosa and Staphylococcus spp. Among all studied samples, 31.9% contained CTX-M-like genes, 5% VIM genes, 1.8% NDM genes, and 3.0% — OXA-48-like genes, and 5.6% of samples contained two and more genetic determinants associated with resistance, with the most prevalent gene combination being the combination of CTX-M- and OXA-48-like genes. In 69 samples with identified species of uropathogens, resistance profile to antimicrobial, determined by microbiological methods, correlated with detected resistance genetic determinants.Conclusion. Authors suggest that introduction of testing for the presence of genes associated with antibacterial resistance to general clinical practice would not only provide an opportunity to conduct epidemiological monitoring of the genetic determinants of antibiotic resistance, but also provide an opportunity to select the correct timely treatment of childhood bacteriuria caused by antibiotic-resistant infectious agents.