ABSTRACT
Acinetobacter baumannii is one of the significant healthcare-associated meningitis agents characterized by multidrug resistance and a high mortality risk. Thirty-seven A. baumannii strains were isolated from thirty-seven patients of Moscow neuro-ICU with meningitis in 2013-2020. The death rate was 37.8%. Strain susceptibility to antimicrobials was determined on the Vitek-2 instrument. Whole-genome sequencing was conducted using Illumina technology; the sequence types (ST), capsular types (KL), lipooligosaccharide outer core locus (OCL), antimicrobial resistance genes, and virulence genes were identified. The prevalent ST was ST2, belonging to the international clone IC2, and rarer, ST1, ST19, ST45, ST78, ST106, and ST400, with prevalence of KL9 and OCL1. Twenty-nine strains belonged to multidrug-resistant (MDR) and eight extensively drug-resistant (XDR) categories. Genes conferring resistance to beta-lactams (blaPER, blaGES, blaADC, blaCARB, blaCTX-M, blaTEM, and blaOXA-types), aminoglycosides (aac, aad, ant, aph, and arm), tetracyclines (tet), macrolides (msr and mph), phenicols (cml, cat, and flo), sulfonamides (dfr and sul), rifampin (arr), and antiseptics (qac) were identified. Virulence genes of nine groups (Adherence, Biofilm formation, Enzymes, Immune evasion, Iron uptake, Regulation, Serum resistance, Stress adaptation, and Antiphagocytosis) were detected. The study highlights the heterogeneity in genetic clones, antimicrobial resistance, and virulence genes variability among the agents of A. baumannii meningitis, with the prevalence of the dominant international clone IC2.
ABSTRACT
Mycobacterium tuberculosis Beijing genotype associated with drug resistance is a growing public health problem worldwide. The aim of this study was the assessment of virulence for C57BL/6 mice after infection by clinical M. tuberculosis strains 267/47 and 120/26, which belong to the modern sublineages B0/W148 and Central Asia outbreak of the Beijing genotype, respectively. The sublineages were identified by the analysis of the strains' whole-genomes. The strains 267/47 and 120/26 were characterized as agents of pre-extensively drug-resistant (pre-XDR) and multidrug-resistant (MDR) tuberculosis, respectively. Both clinical strains were slow-growing in 7H9 broth compared to the M. tuberculosis H37Rv strain. The survival rates of C57BL/6 mice infected by 267/47, 120/26, and H37Rv on the 150th day postinfection were 10%, 40%, and 70%, respectively. Mycobacterial load in the lungs, spleen, and liver was higher and histopathological changes were more expressed for mice infected by the 267/47 strain compared to those infected by the 120/26 and H37Rv strains. The cytokine response in the lungs of C57BL/6 mice after infection with the 267/47, 120/26, and H37Rv strains was different. Notably, proinflammatory cytokine genes Il-1α, Il-6, Il-7, and Il-17, as well as anti-inflammatory genes Il-6 and Il-13, were downregulated after an infection caused by the 267/47 strain compared to those after infection with the H37Rv strain.
ABSTRACT
Klebsiella pneumoniae is an increasingly important hospital pathogen. Classical K. pneumoniae (cKp) and hypervirulent K. pneumoniae (hvKp) are two distinct evolutionary genetic lines. The recently ongoing evolution of K. pneumoniae resulted in the generation of hybrid hvKP-MDR strains. K. pneumoniae distinct isolates (n = 70) belonged to 20 sequence types with the prevalence of ST395 (27.1%), ST23 (18.6%), ST147 (15.7%), and ST86 (7.1%), and 17 capsular types with the predominance of K2 (31.4%), K57 (18.6%), K64 (10.0%), K1 (5.7%) were isolated from patients of the Moscow neurosurgery ICU in 2014-2019. The rate of multi-drug resistant (MDR) and carbapenem-resistant phenotypes were 84.3% and 45.7%, respectively. Whole-genome sequencing of five selected strains belonging to cKp (ST395K47 and ST147K64), hvKp (ST86K2), and hvKp-MDR (ST23K1 and ST23K57) revealed blaSHV, blaTEM, blaCTX, blaOXA-48, and blaNDM beta-lactamase genes; acr, oqx, kpn, kde, and kex efflux genes; and K. pneumoniae virulence genes. Selective pressure of 100 mg/L ampicillin or 10 mg/L ceftriaxone induced changes of expression levels for named genes in the strains belonging to cKp, hvKp, and hybrid hvKp-MDR. Obtained results seem to be important for epidemiologists and clinicians for enhancing knowledge about hospital pathogens.
