Pathogenic Determinants of Clinical Klebsiella Pneumoniae Strains Associated with Their Persistence in the Hospital Environment

Background: Klebsiella pneumoniae is considered an opportunistic pathogen associated with nosocomial infections occurring mainly in pediatric patients, such as premature infants placed in intensive care units. The aim of this study was to characterize K. pneumoniae strains isolated from different clinical sources based on their resistance to antibiotics and the presence of virulence factors associated with their persistence in the hospital environment. Methods: Fifty clinical strains of K. pneumoniae isolated from urine, blood, catheters, and cerebrospinal fluid sources were characterized. Susceptibility testing of antibiotics was performed by the Kirby-Bauer method (Clinical Laboratory Standards Institute, 2010). The ability to form a biofi lm was determined by the 96-well microplate method. Capsule and fi mbrial structures were visualized by transmission electron microscopy (TEM). Adherence was evaluated on A549 and HT29 cells. Assessment for the presence and expression of the ecpA, fi mH, and mrkA genes was performed by PCR and RT-PCR. Results: Clinical strains of K. pneumoniae were isolated from 48% of urine, 24% of blood, 18% of catheters, and 10% of cerebrospinal fl uid. Ninety-two percent of the strains showed resistance to cefpodoxime, whereas few strains showed resistance to imipenem and meropenem (4 and 2%, respectively). The extended spectrum-type beta-lactamase (ESBL) phenotype was identifi ed in 97% of the strains positive for resistance to third-generation cephalosporins. In addition, 88% of the strains were multidrug resistant. All strains were able to form biofi lms. Capsule and fi mbirial structures were visualized by TEM. Based on our adhesion assays, the A549 cell line was more