Investigation of carbapenemase and ESBL status, capsule serotypes, and clinical distribution of virulence genes in Klebsiella pneumoniae isolates

Authors : Başak Baykara, Hamdullah Suphi Bayraktar, Fariz Selimli
Pages : 1153-1162
Doi:10.17826/cumj.1781009
View : 84 | Download : 208
Publication Date : 2025-12-22
Article Type : Research Paper
Abstract :Purpose: This study aimed to (i) determine the prevalence of capsule serotypes and virulence genes in Klebsiella pneumoniae clinical isolates obtained from the Çukurova region of Turkey, and (ii) assess their relationship with carbapenemase and extended-spectrum β-lactamase (ESBL) production. Materials and Methods: A total of 353 K. pneumoniae isolates were recovered from various clinical specimens of both inpatients and outpatients. Carbapenem susceptibility and ESBL production were initially evaluated using an automated antimicrobial susceptibility testing system and subsequently confirmed by the Kirby–Bauer disc diffusion assay and the combined disc method, following EUCAST 2025 guidelines. Genomic DNA was extracted from overnight cultures, and species identification was verified using PCR targeting the 16S–23S ITS region. Capsule serotypes and virulence-associated genes were detected through specific PCR-based assays. Results: Carbapenemase and ESBL production were identified in 26.1% (n = 92) and 23.2% (n = 82) of isolates, respectively, with 17.3% (n = 61) co-producing both enzymes. Capsule serotypes were detected in 11.6% of isolates, predominantly K2 (5.1%, n = 18) and K5 (6.5%, n = 23), whereas K1 was not found. The frequencies of virulence genes were as follows: mrkD (90%), fimH-1 (80%), ybtS (92%), iutA (78%), rmpA (10%), and iroN (2%). A statistically significant association was observed between antimicrobial resistance phenotypes and selected virulence genes, including mrkD, ybtS, and iutA. Conclusion: The findings reveal the distribution of capsule serotypes and virulence determinants among K. pneumoniae isolates circulating in the Çukurova region. These results highlight the importance of sustained molecular surveillance to inform infection control strategies and optimize antimicrobial stewardship.
Keywords : Karbapenemaz, Kapsül serotipi, GSBL, Hastane kökenli enfeksiyonlar, Klebsiella pneumoniae, Virulans genleri

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