Resistance patterns and virulence factors of Pseudomonas aeruginosa in hospitalized patients: A Saudi Arabian study

This study explores antibiotic resistance profiles in Pseudomonas aeruginosa infections among patients in a tertiary hospital in a developing nation. It aims to identify associated factors to enhance treatment strategies in the face of increasing resistance challenges. A retrospective observational study conducted at King Khalid Hospital, Saudi Arabia, from January 2019 to December 2020 analysed patients admitted with positive Pseudomonas aeruginosa cultures. It investigated Pseudomonas infection epidemiology, patient clinical characteristics, and antibiotic susceptibility patterns in 817 samples. A total of 817 patients were included, with a male predominance (63.8%). Common comorbidities included cardiovascular disease (53.7%), diabetes mellitus (36.3%), and cancer (14.8%). Invasive device use was frequent, with 41.1% having Foley catheters, 44.8% central lines, and 22.9% undergoing prolonged intubation. Most P. aeruginosa isolates (70.8%) were identified within three days of admission. Among 1,619 processed samples, sputum was the most common clinical specimen, while rectal swabs predominated among surveillance samples. Colistin (84.5%), amikacin (83.0%), and cefepime (73.2%) showed the highest susceptibility rates, while ceftazidime had the lowest (34.6%). MDR was observed in 73% of isolates and was significantly associated with tracheal intubation (p = 0.0003), central lines (p = 0.032), and hospital-onset infection (p < 0.001). Diabetes mellitus was linked to community-onset cases (p = 0.0457). Hospital-acquired cases were significantly associated with device use and dialysis. Phenotypically, phospholipase C was associated with non-MDR isolates, while biofilm formation correlated with MDR strains. Hemolysin and alkaline protease were not significantly linked to resistance. Genotypically, toxA and plcH were more prevalent in non-MDR isolates, while other virulence genes showed no significant differences. Biofilm production was significantly associated with the plcN gene. The study emphasises the critical prevalence of MDR Pseudomonas aeruginosa (73%), which is strongly linked to invasive medical devices and hospital-onset cases. High resistance to common antibiotics demands enhanced infection control, antimicrobial stewardship, and targeted strategies for high-risk patients to mitigate nosocomial infections and improve outcomes.