Analysis of Phenotypic Diversity and Antibiotic Resistance in Staphylococcus spp. Isolated from Hospital Surfaces in Iraq

Hospitals acquire dangerous transmission routes because their environmental surfaces become permanent breeding grounds for all Staphylococcus species which include methicillin-resistant strains. Hardly any data are available on Iraqi hospital settings that would include detailed phenotypic virulence characterization combined with susceptibility testing. To achieve this objective, a study was carried out in a hospital under the teaching category located in Baghdad. The total number of 250 swabs from high-touch surfaces across ward zones (bed rails, ventilator panels, nursing stations, door handles, infusion pumps, tray tables) was collected. The researchers performed standard bacteriology and biochemical testing through three different procedures which included Mannitol Salt Agar testing and Gram staining and catalase/coagulase examination. The automated identification system VITEK-2 was used to create simulated species confirmation for testing purposes on a selection of swabs. CLSI 2023 disk diffusion method was used to determine the antimicrobial susceptibility further supporting the use of cefoxitin to infer methicillin resistance. Phenotypic virulence assays included microtiter plate biofilm (crystal violet), hemolysin on blood agar, and slime production on Congo red agar. Data were analyzed in SPSS v.28; chi-square/Fisher exact and ANOVA were used where appropriate, with p<0.05 considered significant. Results: Staphylococcus spp. were isolated from 120 of the 250 samples examined (48.0% positivity). The distribution of the species was: S. aureus 45 (37.5%), S. epidermidis 40 (33.3%), S. haemolyticus 20 (16.7%), S. hominis 8 (6.7%), S. saprophyticus 7 (5.8%). Resistance to methicillin (with cefoxitin as a surrogate) was observed in 44.2% (53/120) of the samples in total: MRSA accounted for 20/45 (44.4%) and MR-CoNS for 33/75 (44.0%). Resistance was most common in the case of erythromycin (51.7%) and least in the case of vancomycin (0.0%) and linezolid (3.3%). Biofilm producers were strong in 45 isolates (37.5%) and were related to methicillin resistance (χ2 test, p = 0.0038). No significant differences regarding erythromycin resistance were observed between S. aureus and CoNS (p = 0.22); however, ciprofloxacin resistance was borderline significant for higher rates in CoNS (p = 0.053). Conclusion: The surfaces that were frequently touched in this teaching hospital in Iraq were contaminated with a high number of Staphylococcus spp., and a big part of the isolates was methicillin-resistant as well as biofilm- producing. These results highlight the necessity for specific environmental cleaning, regular monitoring combining resistance and phenotypic virulence profiling, and strengthening of infection prevention measures to reduce HAI risk.