A new Streptococcus group A M-29 variant isolated during a suspected common-source epidemic

Area of Science:

• Microbiology
• Epidemiology
• Public Health

Background:

• Acute pharyngitis outbreaks can pose significant public health challenges.
• Group A Streptococcus (GAS) is a common cause of bacterial pharyngitis.
• Identifying novel strains is crucial for effective outbreak management.

Purpose of the Study:

• To investigate the cause of a large acute pharyngitis epidemic at an Israeli military base in 1988.
• To characterize the specific strain of group A Streptococcus responsible for the outbreak.
• To discuss the implications of unusual Streptococcus strains in food-borne disease outbreaks.

Main Methods:

• Epidemiological investigation of the outbreak, including analysis of the epidemic curve.
• Microbiological analysis of throat swabs from affected individuals.
• Serotyping of group A Streptococcus isolates to identify M protein variants.

Main Results:

• The epidemic presented with clinical features of acute pharyngitis and followed a common-source outbreak pattern, likely food-borne.
• Throat swabs confirmed the presence of group A Streptococcus in a sample of cases.
• All nine analyzed isolates belonged to a single strain with a novel M-29 protein variant.

Conclusions:

• The 1988 Israeli military base outbreak was attributed to a distinct, previously undescribed strain of group A Streptococcus.
• The findings underscore the importance of monitoring and characterizing unusual Streptococcus strains, particularly in food-borne transmission scenarios.
• Further research into the epidemiology and virulence of novel GAS strains is warranted.