Susceptibility and emm type of Streptococcus pyogenes isolated from children with severe infection

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Pediatrics

Background:

• Invasive Streptococcus pyogenes infections pose a significant threat, particularly in pediatric populations.
• Understanding antimicrobial susceptibility is crucial for effective treatment of these infections.

Purpose of the Study:

• To determine the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of various antimicrobial agents against Streptococcus pyogenes strains from children with invasive infections.
• To evaluate the efficacy of different antibiotics, including carbapenems, against prevalent emm types of Streptococcus pyogenes.

Main Methods:

• Collected 12 strains of Streptococcus pyogenes from pediatric patients with invasive infections (2003-2012).
• Determined MICs and MBCs for penicillin G, ampicillin, cefotaxime, ceftriaxone, panipenem, meropenem, and doripenem.
• Classified strains by emm type, with emm1 and emm12 being the most prevalent.

Main Results:

• Carbapenems (panipenem, meropenem, doripenem) exhibited superior antimicrobial activity with very low MIC90/MBC90 values (≤0.004 to 0.008 μg/mL).
• Penicillin G and ceftriaxone also showed good activity, while ampicillin and cefotaxime were slightly less potent.
• The study included a diverse age range of pediatric patients, with half being younger than 5 years, including neonates.

Conclusions:

• Carbapenems are highly effective against contemporary strains of Streptococcus pyogenes causing invasive infections in children.
• The findings support the use of carbapenems for treating severe Streptococcus pyogenes infections, especially in pediatric cases.
• Continued surveillance of antimicrobial resistance patterns is essential for guiding clinical practice.