A Molecular detection of some capsular Serotypes Genes in multidrug resistance Klebsiella pneumonia classical and hyper virulent in Iraqi patients

Klebsiella pneumoniae is an opportunistic pathogenic bacterium and a major cause of nosocomial infections. This study aimed to detect selected capsular serotype genes in multidrug-resistant hypervirulent (hvKp) and classical (cKp) K. pneumoniae isolates from urinary tract infection (UTI) cases using conventional polymerase chain reaction (PCR). This cross-sectional study included 250 urine samples collected from male and female patients aged 18–65 years presenting with UTI symptoms. The study was conducted at Medical City Hospital, Baghdad, Iraq, from October 2023 to February 2024. Samples were cultured on MacConkey agar, nutrient agar, blood agar, and UTI medium for bacterial isolation. Identification was performed using standard biochemical tests and confirmed by the VITEK 2 compact system for antibiotic susceptibility profiling. The string test was used to differentiate hvKp from cKp strains. Capsular serotype genes K1 and K2 were detected in selected multidrug-resistant K. pneumoniae isolates using conventional PCR. Of the 250 urine samples, 201 (84.6%) showed positive bacterial growth. The mean patient age was 54 ± 12 years, with a higher prevalence of UTIs in females. Escherichia coli and K. pneumoniae were the most frequently isolated pathogens. Among the 62 K. pneumoniae isolates, 21 (33.9%) were identified as hvKp and 41 (66.1%) as cKp. Antibiotic susceptibility testing showed that 34% of cKp isolates were multidrug-resistant (MDR), while 90.4% of hvKp isolates exhibited MDR profiles. Molecular analysis of 42 selected MDR K. pneumoniae isolates (21 cKp and 21 hvKp) revealed that 19 of the cKp isolates harbored capsular genes—K1 in 11 isolates (57.9%) and K2 in 8 (42.1%). Among hvKp isolates, 18 carried capsular genes, with K1 in 7 isolates (39%) and K2 in 9 (50%). Conclusion: Hypervirulent K. pneumoniae isolates showed a higher frequency of multidrug resistance and extended-spectrum β-lactamase (ESBL) production compared to classical strains. The K1 and K2 capsular serotypes were predominant among hvKp isolates, while both were also present in cKp strains but at varying proportions.