Approach

Antibiotic treatment of pertussis and judicious use of antimicrobial agents for post-exposure prophylaxis will eradicate Bordetella pertussis from the nasopharynx of infected people (symptomatic or asymptomatic), preventing transmission to susceptible people.[34] While antimicrobials administered during the catarrhal stage may reduce the duration and severity of disease, treatment initiated after paroxysms are established may have no clinical effect.[1]​​[2][10]

Treatment is recommended for patients within 3 weeks of cough onset, and within 6 weeks for pregnant women, immunocompromised people, infants younger than 1 year, or those at high risk of severe pertussis.[30]​ Treatment prior to test results should be considered if the clinical history is suggestive of pertussis or the patient is at high risk of severe pertussis because of the highly transmissible nature of the infection and potential delays in obtaining diagnostic test results.

First-line treatment for suspected or confirmed cases of pertussis is a macrolide antibiotic (azithromycin, clarithromycin, erythromycin).[10][27][30]​ Azithromycin and clarithromycin are generally preferred because of fewer adverse drug effects and more convenient dosing regimens. Macrolides are contraindicated in patients with a history of hypersensitivity to any agent in this class and should be used cautiously in patients with a prolonged QT interval or who are receiving other agents associated with QTc prolongation. These drugs inhibit the CYP3A class of cytochrome P450 enzymes, and co-administration with another agent that is metabolised by these enzymes may alter the metabolism of the concomitantly administered drug. The use of erythromycin and azithromycin in young infants has been associated with an increased risk of infantile hypertrophic pyloric stenosis, but the benefits of azithromycin are considered to outweigh risks in this age group.[10][27][30]

Trimethoprim/sulfamethoxazole may be used in patients aged ≥2 months if macrolides are contraindicated or if a macrolide-resistant B pertussis strain is identified.[10][27]

Young infants (aged <1-2 months) are at high risk for severe pertussis, including life-threatening complications such as apnoea. Providers should anticipate this possibility and consider hospitalising these children for observation and treatment.

Treatment for infants aged <1 month

Azithromycin is the preferred treatment for infants less than aged 1 month.[10][27]​​ Erythromycin is an alternative. The use of erythromycin and azithromycin in young infants has been associated with an increased risk of infantile hypertrophic pyloric stenosis. The benefits of treatment, however, are considered to outweigh the small risk of pyloric stenosis in this age group. Antibiotic regimens may vary in different locations and you should consult your local guidance. Clarithromycin is not recommended in this age group in the US, but is the preferred therapy in the UK, where erythromycin is not recommended for treatment of young infants because of its association with hypertrophic pyloric stenosis. Trimethoprim/sulfamethoxazole is contraindicated in patients aged <2 months and preterm infants because it may displace bilirubin from protein binding sites, potentially leading to hyperbilirubinaemia.[10][27]

Treatment for infants and children aged ≥1 month and adults

Azithromycin, clarithromycin, and erythromycin are equally effective; the choice of agent should consider contraindications, the potential for adverse events and drug interactions, tolerability, and ease of adherence to the regimen prescribed. Azithromycin and clarithromycin are generally better tolerated, and have more convenient dosing regimens.[10] Antibiotic regimens may vary in different locations and you should consult your local guidance.​

Trimethoprim/sulfamethoxazole may be used in patients aged ≥2 months if macrolides are contraindicated or if a macrolide-resistant B pertussis strain is identified.[30] Sulfa antibiotics may displace bilirubin from protein binding sites, potentially leading to hyperbilirubinaemia and kernicterus in neonates and young infants. Use is contraindicated in infants aged <2 months and preterm infants.[10][27]

Patients with pertussis should be excluded from healthcare, childcare, and school settings until they have completed at least 5 days of antimicrobial treatment, or for 21 days from the onset of cough if they are untreated.[1][10]​ This recommendation is consistent with current US guidelines, including the Centers for Disease Control and Prevention (CDC) Pink Book and the American Academy of Pediatrics (AAP), as well as mandates from many state health departments.[1][10][35]​ It is important to refer to the specific public health recommendations in your area to confirm the required time for returning to work, school, or childcare, as guidance may vary. Standard and droplet infection prevention precautions are appropriate for hospitalised patients for the same intervals.

Treatment for pregnant patients

Of the macrolides, clarithromycin should not be used in pregnant women unless the benefits outweigh the risks and no alternative therapy is available. In the UK, erythromycin is preferred for the treatment of pregnant women; clarithromycin and azithromycin are not recommended.[27]

An increased risk of congenital malformations following maternal use of trimethoprim/sulfamethoxazole during pregnancy has been observed. It should be used during pregnancy only if the benefits outweigh the risks to the fetus, especially during the first trimester.

Symptomatic treatments

Antimicrobial therapy early in the course of infection may reduce the severity and duration of cough but is not effective when initiated after the catarrhal stage. The cough is often refractory to conventional adjunctive therapies. Currently there is insufficient evidence to support the use of dexamethasone, salbutamol, or diphenhydramine for symptomatic treatment of cough.[36]

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