Efflux-Mediated Macrolide Resistance in Clinical Streptococcus Isolates: A Comparative Molecular Study

Area of Science:

• Microbiology
• Molecular Epidemiology
• Antimicrobial Resistance

Background:

• Efflux-mediated macrolide resistance in Streptococcus poses a growing global health concern.
• Limited molecular epidemiological data exist for this resistance mechanism in the United Arab Emirates (UAE).

Purpose of the Study:

• To investigate efflux pump-mediated macrolide resistance mechanisms in clinical Streptococcus isolates from the UAE.
• To characterize the prevalence of specific resistance genes, including mef(A/E), msr(D), and tet(K).

Main Methods:

• A cross-sectional study of 100 clinical isolates (99 Streptococcus, 1 Enterococcus) from the UAE.
• Antimicrobial susceptibility testing (MIC determination) and PCR for resistance genes (mef(A/E), msr(D), tet(K)) with sequencing.
• Comparative genomic analysis with publicly available Streptococcus genomes from India and Saudi Arabia.

Main Results:

• 39% of isolates were resistant to erythromycin and 31% to clindamycin.
• The mef(A/E) gene was detected in 31% of isolates and was the strongest predictor of macrolide resistance (OR = 18.7, p < 0.001).
• Significant regional differences in mef(A/E) prevalence were observed: 31% (UAE), 87% (India), 0% (Saudi Arabia).

Conclusions:

• This study provides the first molecular characterization of efflux-mediated macrolide resistance in UAE Streptococcus isolates.
• The predominance of mef(A/E)-mediated resistance highlights its clinical significance in the region.
• Active surveillance and targeted antimicrobial stewardship are crucial for managing this resistance.