From the Guidelines
Yes, very low level pertussis detected on a nasopharyngeal swab typically requires treatment, even with minimal bacterial load. The recommended treatment is a 5-day course of azithromycin (10 mg/kg on day 1, maximum 500 mg, followed by 5 mg/kg on days 2-5, maximum 250 mg daily) 1. Alternative antibiotics include clarithromycin (15 mg/kg/day divided twice daily for 7 days, maximum 1 g/day) or trimethoprim-sulfamethoxazole (8 mg/kg/day trimethoprim component, divided twice daily for 14 days) for those who cannot take macrolides. Key considerations for treatment selection include effectiveness, safety, tolerability, ease of adherence, and cost 1. Treatment should begin immediately after diagnosis, regardless of symptom duration, to reduce transmission risk. The patient should be considered infectious until completing 5 days of appropriate antibiotic therapy. Even low bacterial loads can cause disease transmission, and early treatment helps prevent spread to vulnerable populations like infants and immunocompromised individuals. While antibiotics may not significantly alter the course of illness if started late (after 2-3 weeks of symptoms), they remain important for reducing transmission risk in all cases. It's also important to consider prophylaxis for close contacts, particularly household members, as outlined in guidelines 1. However, the primary focus for the patient with a confirmed diagnosis is initiating appropriate antibiotic therapy as soon as possible to minimize the risk of transmission to others. Given the potential for severe outcomes in vulnerable populations, prioritizing treatment based on the most recent and highest quality evidence is crucial 1.
Key Points for Treatment:
- Azithromycin is recommended for 5 days as the first-line treatment.
- Clarithromycin or trimethoprim-sulfamethoxazole can be used as alternatives.
- Treatment should start immediately after diagnosis.
- The patient is considered infectious until 5 days of appropriate antibiotic therapy are completed.
- Early treatment is crucial to prevent spread to vulnerable populations.
Considerations for Choosing Antibiotics:
- Effectiveness against Bordetella pertussis.
- Safety profile, including potential side effects and drug interactions.
- Tolerability and ease of adherence to the treatment regimen.
- Cost of the antibiotic. Given these considerations and the evidence from 1, azithromycin is the preferred initial treatment due to its effectiveness, better tolerability, and fewer side effects compared to erythromycin.
From the FDA Drug Label
Erythromycin is effective in eliminating the organism from the nasopharynx of infected individuals, rendering them noninfectious Pertussis (whooping cough) caused by Bordetella pertussis.
Treatment is recommended for individuals with a detected level of Bordetella pertussis, as erythromycin is effective in eliminating the organism from the nasopharynx, rendering them noninfectious 2.
From the Research
Antibiotic Treatment for Pertussis
- Antibiotic treatment is intended to prevent transmission of pertussis to others and does not shorten the disease course or improve symptoms 3
- Azithromycin is the preferred antibiotic for treatment or prophylaxis 3
- Effective regimens for pertussis treatment include three days of azithromycin, seven days of clarithromycin, seven or 14 days of erythromycin estolate, and 14 days of erythromycin ethylsuccinate 4
- Short-term antibiotics (azithromycin for three days, clarithromycin for seven days, or erythromycin estolate for seven days) were equally effective with long-term antibiotic treatment (erythromycin estolate or erythromycin for 14 days) in the microbiological eradication of Bordetella pertussis from the nasopharynx 4
Detection of Bordetella pertussis
- A very low level of Bordetella pertussis detected on a nasopharyngeal swab may still require antimicrobial treatment to prevent transmission to others 3
- Polymerase chain reaction testing has replaced culture as the preferred confirmatory test for pertussis diagnosis 3
Comparison of Antibiotics
- Azithromycin is as effective as and better tolerated than erythromycin estolate for the treatment of pertussis 5
- Gastrointestinal adverse events were reported less frequently in azithromycin than in erythromycin estolate recipients 5
- Compliance with therapy was markedly better with azithromycin than with erythromycin 5
- Azithromycin was associated with significantly higher completion rates than erythromycin due to side effects 6