Virulence Genes and Genomic Features of Colistin Resistant <em>Klebsiella pneumoniae</em> Colonizing the Intestinal Tracts of Hospitalized Patients in a Tertiary Hospital, Uganda.

Klebsiella pneumoniae is a leading cause of healthcare acquired infections. The severity of the infections is multifactorial including virulence and antimicrobial resistance properties. The objective of the study was to investigate the virulence determinants of K. pneumoniae strains colonizing patients hospitalized in the intensive care units (ICU) of a tertiary hospital in Uganda. A hospital based cross-sectional study involving 103 patients admitted in the ICU of Mulago National Referral hospital was conducted from January 2022 to April 2022. A total of 31 identified clinical strains of K. pneumoniae isolated from rectal swabs of the same number of patients were characterized. Susceptibility testing of colistin was performed by broth microdilution method, thereafter, 5 colistin resistant K. pneumoniae were purposefully selected for whole genome sequencing. Bioinformatics analysis was performed using established web-based tools to detect virulence genes, sequence type and other genomic features. Numerous virulence factor genes related to pathogenicity of K. pneumoniae were identified. They ranged from those related to colonization to those of persistence and dissemination including capsule genes (wzi), siderophore systems; yersiniabactin (ybt15), aerobactin (iutA), enterobactin (entC, entD, entF, entS, fepB, fepD, fepG, fes), and salmochelin (iroN), secretion systems; type II (T2SS) and type VI (T6SS-1). Furthermore, the isolates harbored outer membrane protein (ompA) gene, biofilm synthesis gene (fimH) and several adhesion genes. The results demonstrate the dual-risk of K. pneumoniae strains combining high level of virulence and colistin resistance which is a great concern as it leads to unmanageable infection outbreaks with high morbidity and mortality.