Microbiological profiles of Gram-negative bacteria isolated from respiratory samples of mechanically ventilated patients at a tertiary Moroccan hospital

Background The prevalence of multidrug-resistant Gram-negative bacteria in mechanically ventilated patients poses a significant threat to treatment efficacy in Morocco. Mechanical ventilation saves many lives in the ICUs. However, treating bacterial infections with high levels of resistance is challenging, which can impact patient outcomes. Objectives to characterise the Gram-negative bacteria implicated in ventilator-associated pneumonia (VAP), focusing on their antimicrobial resistance profiles and phylogenetic relationships. Methods Seventy–eight isolates were collected from protected distal samples over two years; patients were under mechanical ventilation in the three adult ICUs of a Moroccan tertiary hospital. Isolates were identified using VITEK2. PFGE and FTIR determined genetic relationships, whereas the detection of genetic resistance determinants was carried out using PCR. Results Carbapenem-resistant Acinetobacter baumannii harbouring the bla - OXA-23 was the predominant Gram-negative bacterium. Klebsiella pneumoniae was the most prevalent among the Enterobacterales, with a high resistance rate to almost all antibiotics, due to the coexistence of ( bla) CTX-M-1, TEM, SHV , and OXA-48-like genes . Escherichia coli exhibited high resistance to ciprofloxacin (86%), ceftazidime (86%), and cotrimoxazole (71%). Proteus mirabilis was highly resistant to cotrimoxazole (60%) and ticarcillin (80%). Pseudomonas aeruginosa was resistant to carbapenems in 39% of cases, in which bla NDM and bla VIM were the only metallobetalactamase genes detected. In phylogenetic analysis, both FTIR and PFGE techniques underscored no epidemiological relationship among strains. Conclusion The prevalence of MDR and XDR bacteria among VAP cases in a tertiary hospital in Morocco is increasing, potentially due to the coexistence of antimicrobial resistance genes.