What are the clinical effects on chronic carriers of Group A Streptococcus (GAS)?

From the Guidelines

Chronic carriers of Group A Streptococcus (GAS) typically experience no clinical symptoms or adverse health effects from their carrier state, and treatment is generally not recommended unless they have a history of rheumatic fever, live in communities with high rates of rheumatic fever or invasive GAS disease, or during outbreaks of GAS infections. These individuals harbor the bacteria in their throat or on their skin without developing infection or illness, and the carrier state can persist for weeks to months, with approximately 10-20% of school-aged children being asymptomatic carriers 1.

Key Points

• Chronic carriers of GAS are unlikely to spread the organism to their close contacts and are at very low risk, if any, for developing suppurative complications or nonsuppurative complications (e.g., acute rheumatic fever) 1.
• The carrier state exists because GAS can persist intracellularly or within biofilms where standard antibiotics may not reach effective concentrations, and carriers typically have adequate immunity that prevents clinical disease while allowing bacterial colonization.
• When treatment is indicated, clindamycin (20-30 mg/kg/day divided TID for 10 days, max 900 mg/day) or rifampin plus penicillin regimens are often more effective than standard penicillin alone, as outlined in the 2012 update by the Infectious Diseases Society of America 1.
• Helpful clues to differentiate a GAS carrier with an intercurrent viral infection from a patient with acute streptococcal pharyngitis include patient age, season, local epidemiological characteristics, and the precise nature of the presenting signs and symptoms.

Treatment Considerations

• Antibiotics are not generally recommended for chronic carriers, but may be considered in specific situations, such as during a community outbreak of acute rheumatic fever, acute poststreptococcal glomerulonephritis, or invasive group A streptococcal infection 1.
• Treatment regimens for chronic carriers of GAS, as outlined in the 2012 guideline, include oral clindamycin, penicillin and rifampin, amoxicillin-clavulanic acid, and intramuscular benzathine penicillin G, with specific dosing and duration recommendations 1.

From the Research

Clinical Effects on Chronic Carriers of Group A Strep

Chronic carriers of Group A strep are individuals who have a prolonged presence of Group A β-haemolytic Streptococcus (GAS) in the pharynx without evidence of infection or inflammation. The clinical effects on these carriers can be summarized as follows:

• Chronic GAS carriers have a low risk of immune-mediated complications 2
• Persistent pharyngeal carriage often raises management issues, and the management greatly depends on whether the individual belongs to a 'high-risk' group or not 2
• Chronic GAS pharyngeal carriage is quite common, affecting 10-20% of school-aged children, and the pathogenesis of carriage has been related to the pharynx microflora and to special properties of GAS 2

Treatment Options

The treatment options for chronic carriers of Group A strep include:

• Penicillin plus rifampin and clindamycin monotherapy have been recommended for eradication 2
• Limited evidence of effectiveness of azithromycin has been reported 2
• Surgical intervention is not indicated 2
• Antibiotics have a limited effect in the treatment of GABHS pharyngitis, and the results do not demonstrate that other antibiotics are more effective than penicillin 3, 4

Complications and Risks

The complications and risks associated with chronic carriers of Group A strep include:

• Immune-mediated complications, although the risk is low 2
• Suppurative complications, acute rheumatic fever, and post-streptococcal glomerulonephritis, although data on these complications are scarce 3, 4
• Adverse events associated with antibiotic treatment, such as those reported with azithromycin and macrolides 3, 4