Pus-Forming Infections in an Advanced Care Hospital in Morocco: Enterobacterales Dominance With High Burden of...

Background and aim Pus-forming infections are a common cause of morbidity and are increasingly complicated by rising antimicrobial resistance (AMR). This study aimed to describe the bacteriological profile and antimicrobial resistance patterns of bacteria isolated from specimens in an advanced care hospital in Morocco, with a focus on multidrug resistant gram negative bacilli. Methods We conducted a single-centre, observational cross-sectional study from July 2024 to October 2025 in an advanced care hospital in Marrakech, Morocco. All pus specimens (fine-needle aspirates and wound swabs) received in the microbiology laboratory were processed using standard culture methods. Isolates were identified with the Phoenix™ M50 system, and antimicrobial susceptibility testing was conducted by Phoenix™ M50 and disk diffusion, interpreted according to Comité de l'Antibiogramme de la Société Française de Microbiologie (CA-SFM)/European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2025 guidelines. Categorical variables were expressed as counts and percentages; comparisons of proportions were made using the chi-square test or Fisher's exact test when appropriate, with p < 0.05 considered significant. Results Among 469 specimens, 269 yielded bacterial growth (culture positivity rate 57.35%), corresponding to 309 isolates. Most culture positive patients were male (84.01%) and between 60-80 years (55.39%); 92.6% were inpatients. Fine needle aspirates had a higher positivity rate than swabs (60.1% vs 44.2%; p = 0.01). Infections were mainly monomicrobial (83.27%). Gram-negative organisms were the most frequent (66.66%), while gram-positive organisms represented 33.33%. The most frequent pathogens were Escherichia coli (24.59%), Staphylococcus aureus (19.74%), Pseudomonas aeruginosa (12.62%), and Klebsiella pneumoniae (9.70%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in S. aureus was 14.75%; resistance to penicillin G among staphylococci was very high, whereas all staphylococcal and enterococcal isolates remained susceptible to vancomycin and linezolid. Among Enterobacterales (n = 163), 33.74% were resistant to third-generation cephalosporins, and 20.85% expressed an extended-spectrum β-lactamase-producing (ESBL) phenotype; AmpC production was detected in 12.88% overall and in 43.47% of AmpC prone-species. Carbapenem resistance was observed in 24 Enterobacterales (14.72%). In P. aeruginosa, resistance to ceftazidime and/or carbapenems was modest (7.69%), and all isolates were susceptible to amikacin and colistin, whereas 75.0% of Acinetobacter spp. showed extensive drug resistance, with colistin as the only active agent. Conclusions The present study shows that pus-forming infections were dominated by Gram-negative organisms and showed a high burden of ESBL, AmpC and carbapenem-resistant Enterobacterales, contrasting with relatively preserved susceptibility in P. aeruginosa and extensive drug resistance in Acinetobacter spp. Fine-needle aspirates outperformed superficial swabs for pathogen detection. These findings support the use of deep sampling whenever feasible, regular updating of local antibiograms, and rational use of antimicrobial agents, particularly regarding third-generation cephalosporins and carbapenems, to optimize empirical therapy for pus-forming infections in this setting.