Prevalence of inducible clindamycin resistance in macrolide-resistant Staphylococcus spp

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Macrolide resistance is a growing problem in Staphylococcus aureus and coagulase-negative staphylococci (CoNS).
• Inducible clindamycin resistance (ICR) can lead to treatment failures if not detected.
• Phenotypic characterization is crucial for understanding resistance mechanisms.

Purpose of the Study:

• To investigate the prevalence of inducible clindamycin resistance in Staphylococcus aureus and CoNS isolates.
• To compare the frequency of inducible versus constitutive macrolide resistance phenotypes.
• To emphasize the need for routine screening for ICR in staphylococcal infections.

Main Methods:

• Phenotypic testing of macrolide-resistant Staphylococcus aureus (n=45) and CoNS (n=75) isolates.
• Isolates collected from a Greek hospital between January 2002 and December 2003.
• Assessment for inducible and constitutive clindamycin resistance patterns.

Main Results:

• In Staphylococcus aureus, constitutive macrolide resistance (60%) was most common, followed by inducible resistance (35%).
• In CoNS, the inducible resistance phenotype (50%) was more prevalent than the constitutive phenotype (41%).
• A significant incidence of inducible clindamycin resistance was observed in both bacterial groups.

Conclusions:

• Inducible clindamycin resistance is a significant finding in staphylococcal isolates from this Greek hospital.
• Screening all staphylococcal isolates is necessary to distinguish ICR from true susceptibility.
• Accurate identification of ICR is vital for appropriate antibiotic selection and patient management.