Surface Contamination by Multidrug-Resistant Gram-Negative Bacteria in a Healthcare Facility: Resistance Determinants...

Hospital surfaces represent a major reservoir of multidrug-resistant Gram-negative bacteria (MDR-GNB), which contributes to healthcare-associated infections. This study characterized the occurrence, resistance determinants, and biofilm-forming behavior of MDR-GNB isolated from hospital surfaces in a Moroccan regional hospital. Samples were collected from multiple departments and subjected to phenotypic and molecular analysis to characterize antimicrobial resistance, resistance genes, and adhesion properties. Among the 154 sampled surfaces, 62% were contaminated with Gram-negative bacilli, predominantly Acinetobacter baumannii (39%), Escherichia coli (21%), and Enterobacter cloacae (11%). Based on molecular analyses, the key resistance genes were bla _NDM-1, bla _OXA-48, bla _VIM-1, and qacΔE1, and 73% of the isolates were multidrug resistant (a multiple antibiotic resistance index ≥ 0.6). The majority of the isolates (72.7%) were weak biofilm producers. The isolates adhered more strongly to hydrophobic materials (polyvinyl chloride and latex) than to hydrophilic glass (p < 0.001). Principal component analysis and hierarchical clustering linked antimicrobial resistance, biocide tolerance, and surface colonization. The co-occurrence of antibiotic- and disinfectant-resistance genes in MDR-GNB underlies their ability to persist in clinical environments. These findings support risk-based surface hygiene strategies that incorporate molecular surveillance, the selection of proper materials, and targeted disinfection protocols.