From the Guidelines
Yes, a patient can develop a peritonsillar abscess without having group A streptococcal (Strep A) infection. While Strep A is a common cause of peritonsillar abscesses, these infections are often polymicrobial, involving multiple types of bacteria 1. Other causative organisms include anaerobic bacteria (such as Fusobacterium, Peptostreptococcus, and Bacteroides species), other streptococcal species, Staphylococcus aureus, and Haemophilus influenzae. Peritonsillar abscesses typically develop as a complication of acute tonsillitis, when infection spreads beyond the tonsil into the surrounding tissue, creating a collection of pus between the tonsil and its capsule.
Key Points
- Risk factors include untreated or inadequately treated tonsillitis, poor oral hygiene, smoking, and immunocompromised states.
- Treatment generally involves drainage of the abscess (either by needle aspiration or incision and drainage) combined with antibiotics.
- Common antibiotic regimens include amoxicillin-clavulanate (875/125 mg twice daily for 10-14 days), clindamycin (300-450 mg four times daily for 10-14 days), or a combination of penicillin and metronidazole to cover both aerobic and anaerobic organisms 1.
Considerations
- Evidence suggests that antibiotics may prevent complications from group A streptococcal infection, including acute rheumatic fever, peritonsillar abscess, and further spread of group A Streptococcus in outbreaks 1.
- However, little evidence supports the prevention of acute glomerulonephritis 1.
- Antibiotics are not recommended for chronic group A Streptococcus carriers because they are unlikely to spread infection to close contacts and are at little or no risk for complications 1.
From the Research
Peritonsillar Abscess without Strep A
- A peritonsillar abscess can develop without the presence of Streptococcus pyogenes (Strep A) 2, 3, 4, 5.
- The bacteriology of peritonsillar abscesses can vary, with multiple organisms often being isolated from a single sample 2, 3, 4, 5.
- Studies have shown that other microorganisms such as Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, Enterococcus species, Prevotella, Porphyromonas, Fusobacterium, and Peptostreptococcus can be associated with peritonsillar abscesses 2, 3, 4, 5.
- Anaerobic bacteria can be isolated from most abscesses, and the identification of anaerobes has been shown to increase in recent years 3, 4.
- The management of peritonsillar abscesses typically involves aspiration or surgical drainage, followed by appropriate antibiotic therapy, which should be effective against both aerobes and anaerobes 2, 6, 3, 4, 5.
Causative Pathogens
- Streptococcus viridans and Klebsiella pneumoniae have been identified as common microorganisms in peritonsillar abscesses 4.
- Fusobacterium necrophorum and Prevotella melaninogenica are also commonly isolated anaerobes 5.
- The isolation rate of anaerobes has increased in recent years, highlighting the importance of considering anaerobic coverage in antibiotic therapy 4.