Klebsiella pneumoniae clinical isolates: extended spectrum β-lactamase production, biofilm formation, and virulence factors

Abstract

Klebsiella pneumoniae, a Gram-negative bacterium that has emerged as a significant global threat, has been implicated in nosocomial infections. The objectives of this investigation encompassed: i) assessment of extended spectrum ß-lactamase (ESBL) synthesis and other forms of antibiotic resistance, ii) characterization of biofilm formation, adhesin (fimH), and capsule (uge) virulence genes, and iii) exploration of the existence of Class-1 integron (intI1) within the isolates. A total of 120 K. pneumoniae were obtained from clinical specimens and identified with automatic Vitek®2 compact systems. The rates of resistance to various antibiotics were as follows: levofloxacin 89.1%, amoxicillin-clavulanic acid 69.1%, ceftazidime 60%, fosfomycin 59.1%, aztreonam 57.5%, nalidixic acid 56.6%, piperacillin-tazobactam 54.1%, tobramycin 44.1%, chloramphenicol 40%, gentamycin and meropenem 39.1%, imipenem 35.8%. Combined disc testing identified 28 isolates (23.3%) as ESBL-producing K. pneumoniae. The frequency of genes encoding ESBLs is reported as follows: bla_TEM 10 (8.3%), bla_SHV 42 (35%), and bla_CTX-M-I 23 (19.1%). The virulence genes encountered in isolates were adhesin and capsule, 22.5% fimH and 21.6% uge, respectively. The intI1 gene was detected in 70 (58.3%) isolates. Biofilm analysis revealed that 58 isolates (48.3%) were biofilm producers. This study is important for preventing K. pneumoniae infection as it reveals the relationship between antibiotic resistance of isolates, virulence factors, and biofilm formation.