Epidemiological and Clinical Insights into Genotypic Diversity, Antibiotic Resistance Determinants, and Capsular Types of <i>Klebsiella pneumoniae</i> Isolates from Hospitalized Patients in Amol, Northern Iran

Background: Klebsiella pneumoniae is a Gram-negative opportunistic pathogen and a common cause of nosocomial infections. The present study aimed to investigate the distribution, antibiotic resistance patterns, resistance genes, capsular types, and genotypes of K. pneumoniae isolates. Methods: A total of 872 clinical samples were collected from inpatients across various hospital wards in Amol, northern Iran. K. pneumoniae isolates were identified and tested for antibiotic susceptibility. Capsular typing and detection of resistance genes were performed, and enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) was used to type the isolates. Results: K. pneumoniae was isolated from 70 out of 872 samples (8.04%), with the highest prevalence in urine (58.6%) and sputum (25.7%). High resistance rates were observed against erythromycin (98.6%), ampicillin (92.9%), and cefazolin (68.6%), while no resistance to colistin was detected. Multidrug-resistant (MDR) was found in 55.71% of isolates, and 15.71% were extensively drug-resistant (XDR). Carbapenem-resistant K. pneumoniae (CRKP) accounted for 55.7% of the isolates. The most prevalent capsular type was the K57. Forty-eight resistance gene patterns were detected, with the tetB gene present in all isolates, whereas the mcr and blaVEB genes were not detected. ERIC-PCR genotyping revealed 24 different clusters in the phylogenetic dendrogram. Conclusion: This study highlights the prevalence of antibiotic-resistant K. pneumoniae strains exhibiting significant clonal diversity among isolates from hospital wards in Iran. The findings underscore the need for more stringent infection control measures and management practices related to the misuse of antibiotics to tame the rampant resistant K. pneumoniae in hospitals. These results are compatible with the globally prevailing phenomenon of increased resistance and further emphasize the necessity for sustained, in-depth intelligence-gathering processes and multicenter investigations to decode patterns on a regional and international scale.