A high prevalence of mupirocin and macrolide resistance determinant among Staphylococcus aureus strains isolated from...

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Burn Care

Background:

• Staphylococcus aureus infections pose a significant threat to burn patients.
• Antibiotic resistance in S. aureus complicates treatment, especially in vulnerable populations.

Purpose of the Study:

• To investigate the antibiotic resistance profile of S. aureus isolates from burn patients.
• To identify the prevalence and genetic basis of methicillin, erythromycin, and mupirocin resistance.
• To characterize inducible and constitutive clindamycin resistance mechanisms.

Main Methods:

• Polymerase Chain Reaction (PCR) and multiplex-PCR were used to detect resistance genes (mecA, mupA, erm genes).
• Antibiotic susceptibility testing was performed for methicillin, erythromycin, and mupirocin.
• Phenotypic characterization of constitutive and inducible clindamycin resistance.

Main Results:

• High resistance rates were observed: methicillin (58.5%), erythromycin (58%), and mupirocin (40%).
• Ninety-five percent of isolates carried one or more erm genes, with ermA, ermC, and ermB being most common.
• Constitutive and inducible clindamycin resistance were found in 75% and 25% of macrolide-resistant isolates, respectively.
• The mupA gene was present in 25% of isolates.
• A strong correlation was noted between resistance to methicillin, erythromycin, and mupirocin.

Conclusions:

• Burn units may be experiencing an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) with high-level resistance to mupirocin and erythromycin.
• Understanding the genetic basis of resistance (ermA, ermC, ermB, mupA) is crucial for guiding treatment strategies.
• Urgent infection control measures are needed to manage resistant S. aureus strains in burn patients.