Complications of Untreated Streptococcal Infections
Untreated streptococcal infections can lead to serious suppurative and non-suppurative complications including acute rheumatic fever, acute glomerulonephritis, peritonsillar abscess (quinsy), and invasive infections, with potentially significant impacts on morbidity and mortality. 1
Types of Complications
Complications of untreated streptococcal infections can be categorized into two main groups:
1. Suppurative (Local) Complications
- Peritonsillar abscess (quinsy) - A polymicrobial infection occurring mainly in young adults, with Group A Streptococcus as the main causative organism 1
- Acute otitis media - Infection of the middle ear 1
- Cervical lymphadenitis - Inflammation of lymph nodes in the neck 1
- Mastoiditis - Infection of the mastoid air cells behind the ear 1
- Acute sinusitis - Inflammation of the paranasal sinuses 1
2. Non-Suppurative (Systemic) Complications
- Acute rheumatic fever (ARF) - An inflammatory disease that can affect the heart, joints, skin, and brain, occurring 2-3 weeks after untreated Group A streptococcal pharyngitis 1
- Acute post-streptococcal glomerulonephritis - Kidney inflammation occurring a few weeks after streptococcal infection 1, 2
- Streptococcal toxic shock syndrome - A severe systemic infection with multi-organ involvement 3
- Necrotizing fasciitis - Rapidly spreading infection of the fascia ("flesh-eating disease") 3
Risk Factors for Complications
The risk of developing complications varies based on several factors:
- Age - Children under 15 years have higher carriage rates of Group A Streptococcus (10.9%) compared to adults (0.6-2.3%), potentially increasing their risk of complications 1
- Previous history - Patients with a history of rheumatic fever are at higher risk for recurrence 1
- Immunocompromised status - Higher risk of invasive disease 1
- Valvular heart disease - Increased risk of complications 1
- Streptococcal strain - Different serotypes are associated with different complications; rheumatogenic and nephritogenic strains typically belong to different serotypes 2, 4
Timing and Prevention
- Acute rheumatic fever can be prevented if appropriate antibiotic therapy is initiated within 9 days of symptom onset 1
- Post-streptococcal glomerulonephritis can develop regardless of antibiotic treatment 1
- The incidence of rheumatic fever is very low in developed countries but remains several times higher in tropical and developing countries 5
Treatment Considerations
To prevent these complications, appropriate antibiotic therapy is crucial:
- First-line treatment: Penicillin V or amoxicillin for 10 days 6, 7
- For penicillin-allergic patients: Clindamycin, azithromycin, or clarithromycin 6
- Importance of completing treatment: The full 10-day course must be completed to prevent complications, especially rheumatic fever 7
Special Populations
- Children under 3 years often present with fever, mucopurulent rhinitis, excoriated nares, and diffuse adenopathy rather than classic exudative pharyngitis 1
- Adults have a lower risk of first-time acute rheumatic fever even with untreated streptococcal pharyngitis, but can still develop other complications 1
Clinical Pearls and Pitfalls
- Pitfall: Assuming that all sore throats require antibiotics. Only 5-15% of adult cases and 20-30% of pediatric cases of pharyngitis are caused by Group A Streptococcus 1, 8
- Pitfall: Discontinuing antibiotics when symptoms improve. The full 10-day course is necessary to eradicate the organism and prevent complications 7
- Pearl: Patients are considered non-contagious after 24 hours of appropriate antibiotic therapy 6
- Pearl: Carriers of Group A Streptococcus (asymptomatic colonization) have an extremely low risk of developing post-streptococcal complications 1
By promptly identifying and properly treating streptococcal infections, these potentially serious complications can be largely prevented, significantly reducing associated morbidity and mortality.