Macrolide resistance in Streptococcus pyogenes and its correlation with T-type.

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Erythromycin is a key antibiotic for treating streptococcal infections.
• Historically, macrolide resistance in streptococci has been infrequent, primarily linked to serotype T-12.
• Understanding current resistance patterns is crucial for effective treatment strategies.

Purpose of the Study:

• To investigate the prevalence and characteristics of macrolide resistance in Japanese streptococcal strains between 1979 and 1980.
• To correlate erythromycin resistance with specific streptococcal T-types.
• To determine the minimum inhibitory concentrations (MICs) of erythromycin in resistant strains.

Main Methods:

• A 2-year survey (1979-1980) of streptococcal strains isolated across Japan.
• Macrolide resistance testing, focusing on erythromycin.
• Correlation of resistance patterns with streptococcal T-serotypes.
• Determination of MICs for erythromycin-resistant isolates.

Main Results:

• Serotype T-12 strains exhibited high resistance to erythromycin.
• Erythromycin resistance was also detected in T-4 and T-1 serotypes.
• 2.8% of strains showed moderate resistance (MICs 1.56-12.5 µg/mL).
• 25.5% of strains displayed high resistance (MIC ≥ 100 µg/mL).

Conclusions:

• Erythromycin resistance in streptococci, particularly serotype T-12, is a significant concern.
• Resistance is not limited to T-12, with T-4 and T-1 serotypes also affected.
• The study highlights the need for ongoing surveillance of antimicrobial resistance in clinically relevant bacteria.