Clindamycin-resistant among Staphylococcus aureus: Investigation into phenotypic and genotypic profiles

Area of Science:

• Microbiology
• Clinical Diagnostics
• Antimicrobial Resistance

Background:

• Antimicrobial resistance (AMR), especially from methicillin-resistant Staphylococcus aureus (MRSA), is a significant global health threat.
• Increasing resistance to macrolide lincosamide-streptogramin B (MLSB) antibiotics, including clindamycin, is observed in staphylococcal strains.
• Inducible MLSB (iMLSB) resistance is challenging to detect in standard laboratory tests, potentially leading to treatment failures.

Purpose of the Study:

• To evaluate the efficacy of the double disc diffusion (D test) for identifying inducible clindamycin resistance in Staphylococcus aureus.
• To investigate the prevalence of different MLSB resistance phenotypes and their genetic determinants in S. aureus isolates.

Main Methods:

• Phenotypic detection of inducible MLSB (iMLSB) resistance using the double disc diffusion (D test).
• Genotypic identification of resistance genes (erm (A, B, C) and msr) via singleplex PCR.

Main Results:

• Out of 161 S. aureus isolates, 26.1% were erythromycin-resistant, with 15.5% exhibiting the iMLSB phenotype.
• The MSB phenotype was observed in 9.9% of isolates, and one MRSA isolate showed constitutive MLSB (cMLSB) resistance.
• Genotypic analysis indicated ermC prevalence in 60% and msr in 40% of isolates.

Conclusions:

• The D-test is a dependable method for detecting inducible clindamycin resistance in clinical settings.
• Accurate identification of iMLSB is vital for effective antibiotic stewardship and treatment strategies.
• This approach supports appropriate antibiotic use in Qatar to combat AMR.