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Updated: Mar 25, 2026
Genome-wide Gene Deletions in Streptococcus sanguinis by High Throughput PCR
Published on: November 23, 2012
Isolation of Streptococcus pyogenes from children with pharyngitis and emm type analysis
Azar D Khosravi1, Nasim Ebrahimifard2, Ahmad Shamsizadeh3
1Health Research Institute, Infectious, and Tropical Diseases Research Center, Ahvaz, Iran; Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Background:
The group A streptococcus (GAS) M protein, encoded by the emm gene, acts as a major virulence factor. Emm-typing is the GAS gold standard molecular typing and is based on the DNA sequence of the nucleotides of the emm gene. The aim of the present study was to isolate GAS from patients and to detect the emm types of the isolates using emm typing.
Methods:
A total of 1000 throat samples were collected from patients with pharyngitis referred to Aboozar Children's Hospital in Ahvaz, Iran. We performed antimicrobial susceptibility testing on all isolates using the Kirby-Bauer disk diffusion method. Additionally, amplification of the emm gene was performed using polymerase chain reaction using the standard primers and described protocol.
Results:
From all throat samples screened, 25 isolates (2.5%) were identified as GAS. Antibiotic susceptibility testing revealed that all the GAS isolates were susceptible to penicillin and erythromycin, but 44% showed resistance to vancomycin. Based on polymerase chain reaction for the emm gene, the obtained emm types were: emm-3, observed in 20 isolates (80%); emm-1 observed in four isolates (16%); and emm-75 observed in one isolate (4%).
Conclusion:
The result of the present study showed that penicillin and erythromycin are still the most effective antibiotics against the organism. The emm typing revealed that emm type-3 was detected in most of the isolates from patients with purulent pharyngitis. On the basis of the findings of this study, we may conclude that emm typing provides new insights on the genetic diversity of the M proteins, and is of demonstrable value for molecular studies of GAS.
Insights
Group A Streptococcus (GAS) emm typing identified emm type-3 as the most prevalent in Iranian patients with pharyngitis. Penicillin and erythromycin remain effective treatments, while vancomycin resistance was noted in 44% of isolates.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Group A Streptococcus (GAS) M protein is a key virulence factor.
- Emm-typing, based on emm gene sequencing, is the gold standard for GAS molecular typing.
- Understanding GAS emm types is crucial for epidemiological studies and disease control.
Purpose of the Study:
- To isolate GAS from patients with pharyngitis.
- To determine the emm types of the isolated GAS strains.
- To assess antibiotic susceptibility patterns of GAS isolates.
Main Methods:
- Collection of 1000 throat samples from patients with pharyngitis.
- Antimicrobial susceptibility testing using the Kirby-Bauer disk diffusion method.
- Polymerase chain reaction (PCR) amplification of the emm gene for typing.
Main Results:
- 25 GAS isolates (2.5%) were identified.
- All isolates were susceptible to penicillin and erythromycin.
- 44% of isolates exhibited vancomycin resistance.
- Emm typing revealed emm type-3 (80%), emm type-1 (16%), and emm type-75 (4%).
Conclusions:
- Penicillin and erythromycin are effective against GAS isolates in this region.
- Emm type-3 is the predominant type among GAS causing pharyngitis in the studied population.
- Emm typing offers valuable insights into GAS genetic diversity and aids molecular epidemiology.
