Coagulase-negative staphylococci in air samples from operating theatres

Area of Science:

• Microbiology
• Environmental Health
• Clinical Science

Background:

• Coagulase-negative staphylococci (CNS) are common skin flora and potential opportunistic pathogens.
• The presence and characteristics of airborne CNS in operating theatres are crucial for infection control.
• Understanding CNS behavior, including adherence and antibiotic resistance, is vital for preventing surgical site infections.

Purpose of the Study:

• To identify and characterize coagulase-negative staphylococci (CNS) isolated from the air of operating theatres.
• To investigate the adherence properties of CNS strains to glass surfaces.
• To assess the antibiotic susceptibility and phage sensitivity of different CNS species and adherence-positive/negative isolates.

Main Methods:

• Air sampling in operating theatres to collect bacterial isolates.
• Identification of CNS species using standard microbiological techniques.
• Assessment of bacterial adherence to glass surfaces.
• Disk-diffusion assays for antibiotic sensitivity testing (penicillin, tetracycline, erythromycin).
• Phage sensitivity testing for Staphylococcus warneri and S. haemolyticus.

Main Results:

• Out of 449 CNS isolates, Staphylococcus epidermidis and Staphylococcus haemolyticus were the most prevalent species.
• 52.3% of CNS strains exhibited adherence to glass; S. epidermidis predominantly showed adherent growth, while S. haemolyticus largely did not.
• Significant differences in sensitivity to penicillin, tetracycline, and erythromycin were observed between adherence-positive and negative isolates.
• Staphylococcus haemolyticus demonstrated higher resistance to antibiotics compared to S. epidermidis.
• Staphylococcus warneri was most sensitive to phages, whereas S. haemolyticus was least sensitive.

Conclusions:

• Airborne CNS in operating theatres, particularly S. epidermidis and S. haemolyticus, present varied characteristics influencing infection risk.
• Bacterial adherence to surfaces may correlate with differential antibiotic resistance patterns.
• S. haemolyticus exhibits greater antibiotic resistance and lower phage sensitivity than S. epidermidis, highlighting species-specific concerns for hospital environments.