MDR Pseudomonas aeruginosa in Burn Units of Iraq: Resistance Trends, Biofilm Quantification Using Microtiter OD, Predictor of Clinical Outcomes

Abstract

This study aimed to evaluate resistance patterns, longitudinal trends, biofilm production, and clinical determinants of mortality for Pseudomonas aeruginosa isolates from burn units. A multicenter longitudinal observational study included burn patients in whom Pseudomonas aeruginosa was first isolated in a non-recurring setting. The study included 360 burn patients. The majority of the cohort was male (63.1%) with a mean age of 31 years (interquartile range 20–44 years) and a mean burned body surface area of ​​27% (interquartile range 18–41 years). The highest resistance rates were recorded for the following antibiotic classes: ciprofloxacin (61.9%), levofloxacin (59.4%), and aztreonam (57.5%). Resistance rates for carbapenems were 40.3%, for imipenem 43.3%, and for meropenem 43.3%. Bacteria producing biofilms in high density constituted 22.5% of the total bacteria, with a high proportion of multidrug-resistant bacteria (77.8%) and a high proportion of non-drug-resistant bacteria (21.0%) (p < 0.001 and p = 0.002, respectively). In-hospital mortality was 13.6%, with a higher incidence in DTR (28.6 vs 11.8; p = 0.002), a lower incidence in DTR (strong biofilm 19.8 vs 11.7; p = 0.041), and a lower incidence in experimentally ineffective biofilm (25.9 vs 8.9; p < 0.001). Bacteremia was also present (50.0 vs 9.6; p < 0.001). The model demonstrated good discrimination (area under the curve = 0.83). Strong biofilm formation was strongly associated with multidrug resistance/direct immune response and was an independent predictor of mortality. Improving experimental treatment in accordance with more recent unit-specific protocols, antibiotic data, strengthening infection prevention policies, and integrating them with supervisory recommendations are important to reduce harmful procurement.