Clinical Microbiology and Antimicrobial Chemotherapy. 2024; 26(4):496-504
To analyze and compare multidrug-resistant Klebsiella pneumoniae (KP) strains isolated from different sites of the same patients.
A total of 30 KP strains isolated from 15 patients treated in intensive care and surgical units in 2020–2021 were studied. Two strains isolated from one child were selected for analyses. One strain was isolated from a clinically significant site (blood/urine/wound/endotracheal aspirate or sputum), the other from a monitoring site (stool). Antibiotic susceptibility was determined using the broth microdilution method. The presence of beta-lactamase genes of the IMP, NDM, VIM, KPC, OXA-48, CTX-M groups and the mcr-1 gene were detected by real-time PCR. The virulence genes and K1/K2 capsular serotypes were determined by multiplex PCR with detection in 2% agarose gel. Biofilms were grown using flat-bottomed polystyrene plates followed by fixation, staining, elution and result detection. Sequence types (ST) were determined by multilocus sequence typing (MLST).
Most of KP strains were recognized as extensively drug-resistant pathogens (83.3%), five (16.7%) isolates were classified as multidrug-resistant pathogens. Carbapenemase production was detected in 86.7% strains. Carbapenem resistance was associated with OXA-48 carbapenemases (69.2%). Metallobeta-lactamases (MBL) of the NDM group were found in six (23.1%) strains. In two isolates, a combination of NDM and OXA-48 carbapenemases was discovered. Extended spectrum beta-lactamases (ESBLs) of the CTX-M group were detected in 93.3% isolates. All strains had the mrkD and entB virulence genes. The ybtS gene was found in 66.7% isolates. Eight (26.7%) strains harbored the iutA gene. The rmpA gene was detected in two isolates. Four isolates belonged to K2 serotype. The ability to form biofilms was detected in 93.3% strains. Most of the isolates produced biofilms of moderate intensity (57.1%), low-intensity biofilms were detected in 35.7% of isolates, and two strains formed strong biofilms. STs were represented by ST395 (40%), ST307 (20%), ST37 (20%), ST198 (6.7%), ST866 (6.7%), ST147 (6.7%).
The strains isolated from one patient had the same resistance and virulence determinants, belonged to the same sequence types and formed biofilms of the same intensity. The findings suggest that infections in the clinically significant site and the monitoring site were caused by the same KP strain.