Molecular determinants of antimicrobial resistance in <i>Klebsiella pneumoniae</i> isolates among geriatric patients in Chattogram, Bangladesh: a cross-sectional study

ABSTRACT Klebsiella pneumoniae (KPN) infections pose heightened risks in the geriatric population due to weakened immunity, prevalent comorbidities, potential exposure in long-term care settings, and increased likelihood of antibiotic resistance (ABR). The study focused on the prevalence and antibiotic resistance of KPN infections, the presence of ABR genes in KPN, and the genomic characterization of KPN obtained from geriatric patients in Chattogram. A total of 543 specimens were collected from four hospitals in Chattogram, along with demographic data from hospital records. Genomic DNA was extracted from multi-drug-resistant (MDR) KPN, and the presence of ABR genes , bla TEM-1 , sul-1 , aadB , bla NDM-1 , bla SHV-11 , and phoE was identified. To characterize the KPN genomes, two MDR KPN isolates were subjected to whole-genome sequencing (WGS), and the data were analyzed using bioinformatics tools to identify genomic determinants of ABR. KPN exhibited high resistance to ceftazidime (96%), cefuroxime (92%), and cefixime (83%), but sensitivity to colistin (79%) and amikacin (75%). MDR KPN was mostly detected in sputum (36%) and urine (27%) specimens, where the prevalence of ABR genes, blaTEM-1 , sul1 , aadB , blaNDM-1 , and blaSHV-11 were 28.2%, 17%, 6.17%, 56%, and 48% of these strains, respectively. These genomes exhibited distinct profiles for sequence types, ST420 and ST277 in Kpn007 and Kpn016, respectively, and ABR genes ( qnrS1 , blaCTX-M-15 , and blaSHV-27 ), virulence factors ( ybt , iuc1 , iro1 ), and contained both K (K20, K46) and O antigens (O1, O3b). MDR KPN in the geriatric population poses a serious health concern due to their increased vulnerability to infections and limited treatment options, requiring careful management. IMPORTANCE Multidrug resistance (MDR) and the hypervirulence nature of Klebsiella pneumoniae (KPN) in geriatric patients pose a critical health concern in nosocomial infections worldwide and result in high clinical complexity and mortality. The study investigated the factors for KPN infections and analyzed antimicrobial resistance profiles. More than 60% of Klebsiella pneumoniae isolates from geriatric patients were resistant to third- and fourth-generation cephalosporins, and most isolates carried bla NDM-1 and bla SHV-11 genes. Analyzing whole genomes of two KPNs, Kpn007 (ST277) was identified as a hypervirulent strain with aerobactin and yersinia siderophores, contributing to virulence, and Kpn016 (ST420) carried fluoroquinolone ( qnrS1 ), ESBL ( bla CTX-M-15 and bla SHV-27 ) resistance. Both genomes contained K antigens (K20 and K46) and O antigens (O1 and O3b).