Group F streptococci in the pharynx: pathogens or innocent bystanders?

Area of Science:

• Microbiology
• Pediatric Infectious Diseases
• Bacteriology

Background:

• Beta-hemolytic streptococci (BHS) are common causes of bacterial pharyngitis.
• Lancefield group F BHS are less frequently implicated in human infections compared to group A BHS.
• Understanding the role of different BHS groups in pediatric pharyngitis is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To investigate the prevalence and clinical characteristics of Lancefield group F beta-hemolytic streptococci (BHS) isolated from children and adolescents with symptomatic pharyngitis.
• To compare the clinical presentation of pharyngitis caused by group F BHS with that caused by group A BHS.
• To assess the potential role of group F BHS as a cause of nonepidemic pharyngitis in the pediatric population.

Main Methods:

• Throat cultures were obtained from 46 children and adolescents presenting with symptomatic pharyngitis.
• Isolation of beta-hemolytic organisms, including group F BHS, often required microaerophilic conditions (oxygen deprivation using an anaerobe jar).
• Clinical data including fever and cervical adenopathy were compared between children with group F BHS isolates and a control group with group A BHS isolates.

Main Results:

• Moderate to heavy growth of group F BHS was observed in 46 pediatric patients with pharyngitis.
• Growth of these beta-hemolytic organisms frequently necessitated oxygen deprivation.
• Patients with group F BHS isolates were more likely to be adolescents and less likely to present with fever and cervical adenopathy compared to those with group A BHS.

Conclusions:

• Group F BHS may not be a primary cause of nonepidemic pharyngitis in the pediatric age group.
• Further research is needed, including comparing isolation rates in sick versus well children and evaluating serologic responses, to accurately determine the pathogenic role of group F BHS.
• Distinguishing between invasive infection and asymptomatic carriage of group F BHS is essential for understanding their clinical significance.