Risk factors for carbapenem-nonsusceptible Pseudomonas aeruginosa: Case-control study.

The objective of this case case-control study was to identify risk factors for carbapenem-nonsusceptible Pseudomonas aeruginosa in adult acute care hospitalized patient at 2 large academic medical centers. Risk factors were evaluated using logistic regression within a generalized estimating equations framework to account for clustering of patients within study site. Of 1161 total isolates, 271 (23.3%) were carbapenem-nonsusceptible of which respiratory was the most common source (54.3%). In the multivariable model, intra-abdominal (P < 0.0001) and respiratory (P = 0.0014) sources were associated with a higher odds for carbapenem nonsusceptibility when compared to urine source. Prior positive culture (P < 0.0001), use of an antipseudomonal carbapenem in the prior 30 days (P < 0.0001) and culture collection in the intensive care unit (P < 0.0001) were also associated with increased odds for carbapenem-nonsusceptibility. Further studies to validate these findings are warranted.