Molecular characterization of serotype and virulence genes of Pseudomonas aeruginosa isolated from patients admitted at two hospitals in Addis Ababa, Ethiopia

Introduction. Pseudomonas aeruginosa contains a wide range of extracellular and cell-associated virulence factors that support its pathogenesis. The most variable portion of lipopolysaccharide, O-polysaccharide, confers serogrouping and is crucial for virulence. Gap Statement. Despite their importance, P. aeruginosa serotypes and associated virulence factors are not well described at the level of strains obtained from Ethiopian clinical samples. Aim. To characterize the serotypes and virulence factors of P. aeruginosa isolates from patients admitted to two hospitals Addis Ababa, Ethiopia. Methodology. Whole-genome sequencing was performed to characterize genes responsible for serotypes and virulence factors. Results. Eight distinct serotypes were identified, with O6 (50%) and O11 (14.1%) being the most common and O9 (1.6%) being the least common. Serotype O6 was the most frequent serotype in all infections, and the percentage of O11 (38.5%) was high in burn wound isolates. The percentage of multidrug resistance was 56.6%. High levels of resistance to ciprofloxacin (51.8%) and ceftazidime (50.6%) and low levels of resistance to ceftazidime-avibactam (4.8%) were observed. Multidrug-resistant phenotypes were more common for the O11 (88.9%) and O5 (66.7%) serotypes. There were four (6.3%) exoU+ strains and one (1.6%) exoU+exoS+ multidrug-resistant strain, all of which were O11 serotypes. The frequencies of toxA, exoY, pilA and exoT were 93.8%, 96.9%, 17.2% and 96.9 %, respectively. Conclusion. This study showed the presence of highly virulent multidrug-resistant P. aeruginosa strains in Ethiopia, and continuous molecular surveillance is essential for monitoring the spread of these strains and creating efficient management strategies.