PURPOSE: It seems that antibiotics rarely affect the course of the pertussis when they are given in the paroxysmal phase. We specified the kinds of drugs, including antibiotics, and the duration of administration in all patients with pertussis and compared the efficacy of antibiotic therapy between the catarrhal phase and paroxysmal phase.
METHODS: We encountered two outbreaks of Bordetella pertussis infection in universities. The outbreaks occurred between April 25 and August 1, 2010, with eight students, four laboratory staff and eight family members reporting a primary complaint of cough. We diagnosed B. pertussis infection by serology using paired serum samples and a PCR assay. All patients were treated with clarithromycin (400 mg/day) for seven days and tulobuterol (2 mg/day) for 14 days. The treatment group differences were tested using t-test and the significance level was set at 5% (two-sided).
RESULTS: Clinical findings and laboratory data in adult patients with B. pertussis infection demonstrated non-specific cough and normal WBC and lymphocyte count. The patients who received clarithromycin prior to 14 days after clinical onset demonstrated a significantly shorter duration of cough symptoms than the patients who received clarithromycin at 14 days or more after clinical onset (duration of cough after administration of clarithromycin: 16.6±6.88 days versus 32.1±5.68 days, p = 0.0039; duration of total cough after clinical onset: 23.1±6.88 days versus 54.9±6.65 days, p = 0.0005).
CONCLUSIONS: The clinical findings of adult pertussis are different from pertussis in children. The efficacy of macrolide therapy clearly differed between the catarrhal phase and paroxysmal phase. Macrolide antibiotics can improve clinical symptoms of pertussis when they are given early, that is, during the incubation period or in the early catarrhal phase (1 to 2 weeks after onset). When prescribed later, there is less benefit.
CLINICAL IMPLICATIONS: Cough is a quite common symptom and is treated symptomatically without a definitive diagnosis. Physicians should consider B. pertussis in the differential diagnosis of an outbreak of non-specific respiratory infection even in adult populations.
DISCLOSURE: The following authors have nothing to disclose: Naoyuki Miyashita, Kazunobu Ouchi, Niro Okimoto
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