Antibiotic Susceptibility Evaluation of Group A Streptococcus Isolated from Children with Pharyngitis: A Study from
Shirin Sayyahfar1, Alireza Fahimzad2, Amir Naddaf3
1Division of Pediatric Infectious Diseases, Departement of Pediatrics, Ali Asghar Children Hospital, Iran University of Medical Sciences, Tehran, Iran.
Insights
Group A Streptococcus (GAS) in Iranian children shows high resistance to erythromycin and azithromycin, necessitating careful antibiotic selection. Penicillin G remains effective, but local surveillance is crucial for optimal treatment strategies.
Area of Science:
- Microbiology
- Infectious Diseases
- Pediatrics
Background:
- Group A Streptococcus (GAS) pharyngitis is a common childhood infection.
- Antibiotic resistance in GAS impacts treatment efficacy.
- Evaluating local antibiotic susceptibility patterns is essential for guiding clinical practice.
Purpose of the Study:
- To assess the antibiotic susceptibility of Group A Streptococcus (GAS) strains.
- To determine resistance patterns to commonly prescribed antibiotics for GAS pharyngitis in children in Iran.
Main Methods:
- Prospective study of children aged 3-15 with acute tonsillopharyngitis.
- GAS identification using standard microbiological techniques and Lancefield grouping.
- Antimicrobial susceptibility testing via disk diffusion and broth dilution methods.
Main Results:
- 30% of 200 children had GAS-positive throat cultures.
- All GAS isolates were susceptible to penicillin G.
- High resistance rates observed for erythromycin (33.9%), azithromycin (57.6%), and clarithromycin (33.9%).
- Significant resistance also noted for clindamycin (13.5%) and ofloxacin (32.2%).
- 8.4% of strains showed resistance to rifampin.
Conclusions:
- High GAS resistance to macrolides and other antibiotics necessitates judicious antibiotic use in Iran.
- Physicians should be cautious with antibiotic prescriptions to mitigate rising resistance.
- Continuous local surveillance is vital for identifying effective therapeutic options for GAS infections.
Background:
The aim of this study was to evaluate the antibiotic susceptibility of Group A streptococcus (GAS) to antibiotics usually used in Iran for treatment of GAS pharyngitis in children.
Materials And Methods:
From 2011 to 2013, children 3-15 years of age with acute tonsillopharyngitis who attended Mofid Children's Hospital clinics and emergency ward and did not meet the exclusion criteria were enrolled in a prospective study in a sequential manner. The isolates strains from throat culture were identified as GAS by colony morphology, gram staining, beta hemolysis on blood agar, sensitivity to bacitracin, a positive pyrrolidonyl aminopeptidase (PYR) test result, and the presence of Lancefield A antigen determined by agglutination test. Antimicrobial susceptibility was identified by both disk diffusion and broth dilution methods.
Results:
From 200 children enrolled in this study, 59 (30%) cases were culture positive for GAS. All isolates were sensitive to penicillin G. The prevalence of erythromycin, azithromycin, and clarithromycin resistance by broth dilution method was 33.9%, 57.6%, and 33.9%, respectively. Surprisingly, 8.4% of GAS strains were resistant to rifampin. In this study, 13.5% and 32.2% of the strains were resistant to clindamycin and ofloxacin, respectively.
Conclusion:
The high rate of resistance of GAS to some antibiotics in this study should warn physicians, especially in Iran, to use antibiotics restrictedly and logically to prevent the rising of resistance rates in future. It also seems that continuous local surveillance is necessary to achieve the best therapeutic option for GAS treatment.
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