Prevalence and emm typing of multi-drug resistant Streptococcus pyogenes in tertiary care health settings.

Abstract

Background: Streptococcus pyogenes causes diverse infections, including pharyngitis and invasive diseases. Emerging resistance to β-lactams and macrolide poses a significant public health threat in developing countries. This study examines the prevalence, antibiotic susceptibility, and emm types of S. pyogenes strains isolated from hospitals in Khyber Pakhtunkhwa (KP), Pakistan.

Methods: A total of 4,062 clinical samples, including throat swabs, blood, pus, and biopsies, were collected from eight hospitals. S. pyogenes was isolated and identified using standard microbiological techniques. Antibiotic susceptibility tests and Minimum Inhibitory Concentrations (MIC) were investigated using the disc diffusion method and Epsilometer test (E-test), respectively. PCR and DNA sequencing were used to determine the emm typing of the isolates.

Results: Of the 4,062 samples, 471 were positive for S. pyogenes (11.5%). The most common emm types identified were emm12 (16%), emm4 (13%), and emm1 (12%). Isolates from the throat samples predominantly yielded emm1. However, emm12 was most common in biopsy and blood samples, and emm4 was frequently isolated from pus. High resistance to erythromycin (8%) and tetracycline (8%) and no resistance to meropenem, vancomycin, and teicoplanin were recorded. Penicillin resistance ranged from 0.6% to 7.2%, with MIC distribution between 0.07-2.9 mg/L. Factors including low financial status (AOR = 3.18, 95% CI = 1.60-6.32, P = 0.05), self-medication with unprescribed antibiotics (AOR = 5.45, 95% CI = 2.60-11.22, P = 0.04), and presence of comorbidities (AOR = 9.13, 95% CI = 2.54-26.54, P = 0.03) were significantly associated with increased risk of infection.

Conclusion: The emm typing results revealed significant genetic diversity among S. pyogenes isolates, with emm12, emm4, and emm1 being the most prevalent types in KP. This diversity, along with the observed antibiotic resistance patterns, underscores the need for ongoing surveillance and targeted treatment strategies to effectively manage S. pyogenes infections in the region.