Risk factors, antimicrobial susceptibility pattern and patient outcomes of Pseudomonas aeruginosa infection: A matched case-control study.

Abstract Background Pseudomonas aeruginosa is a leading nosocomial Gram-negative bacteria associated with prolonged hospitalization, and increased morbidity and mortality. Limited data exist regarding P. aeruginosa infection and outcome in patients managed in intensive care units (ICUs) in the Gulf countries. We aimed to determine the risk factors, antimicrobial susceptibility pattern and patient outcomes of P. aeruginosa infection in ICU. Methods In this matched case-control study, all P. aeruginosa infections that occurred >48 h after hospital admission between January 31st 2016 and December 31st 2018 at ICUs affiliated with King Abdulaziz Medical City, Riyadh were included. P. aeruginosa was identified using MALDI-TOF (Vitek-MS) by biomerieux, and the antimicrobial susceptibility testing was performed using an automated biomerieux VITEK® 2 Antimicrobial Susceptibility card. Results The study included 90 cases and 90 controls. Compared with controls, cases had significantly higher mean ICU stay and higher proportions with previous history of antimicrobial therapy, coronary artery disease, malignancy, hemodialysis, previous surgery, use of central line, urethral catheterization, nasogastric tube, and tracheostomy. In a multivariate conditional logistic regression analysis, factors independently associated with P. aeruginosa infection were ICU duration [Odds Ratio (OR) 9.05, 95%CI 2.53−32.27, p = .001], previous surgery (OR = 7.33, 95%CI 1.66−32.36, p = .009), tracheostomy (OR = 11.13, 95%CI 1.05−118.59, p = .046), urethral catheterization (OR = 7.38, 95%CI 1.21−45.11, p = .030) and use of aminoglycosides (OR = 10.59, 95%CI 1.14−98.13, p = .038). Approximately 41% of P. aeruginosa isolates were resistant to imipenem, while 36.7% were multidrug-resistant. Mortality was similar in both groups: 54(60%) cases and 51(56.7%) controls; p = .650. Conclusions The study identifies several potentially modifiable factors associated with P. aeruginosa infection in ICUs. Identification of these factors could facilitate case identification and enhance control measures.