Reoccurrence of
Culture-Positive Pertussis in an Infant Initially Treated With Azithromycin
and Steroids
Epidemiologic studies have revealed an increase in the rate of
pertussis infection despite massive vaccination.1,
2 Since no curative treatment is available,
antibacterial therapy with erythromycin, 40 to 50 mg/kg, 4 times per day for
2 weeks, is recommended in reducing the length of the illness and in
limiting the spread of the infection.3
Newly developed macrolides with improved absorption, longer half-lives, and
fewer adverse effects, combined with encouraging efficacy trials, have
demonstrated the superiority of new macrolides over erythromycin in upper
respiratory tract infections.4
This has led to a switch from erythromycin to the newly available macrolides
for the treatment of pertussis. The superiority of short-term treatment with
the newly developed macrolides over the conventional long-term erythromycin
treatment has been demonstrated.5,
6
Report of a Case
A 2-month-old boy was admitted for paroxysmal whooping cough, which began
1 week before admission. The mother and grandmother complained of a mild
cough and rhinorrhea. Neither apnea nor cyanosis was noted during the cough
paroxysm. The child had been vaccinated as scheduled but had not received
the diphtheria-tetanus-pertussis (DTP) vaccine. A complete blood cell count
revealed a hemoglobin level of 12.8 g/dL and a white blood cell count of
39.6 
103/µL, with 76%
lymphocytes. A nasopharyngeal wash culture and polymerase chain reaction for
Bordetella pertussis were positive; IgA and IgM were negative for
organisms.
During the child's first days of hospitalization, the cough attack
worsened. A dose of dexamethasone (0.1 mg/kg) and a 5-day course of
azithromycin (10 mg/kg) were started. The immediate family members were also
examined for pertussis (Table
1). After 1 week of hospitalization, the child's condition improved, the
cough paroxysm diminished, and the patient was discharged to his home. The
parents were advised to have the child vaccinated in the future with
diphtheria and tetanus as recommended. One month after his first admission,
the child was readmitted for the recurrence of the paroxysmal cough, which
was accompanied by perioral cyanosis. A polymerase chain reaction culture
and serologic test results for IgM and IgG were positive for B pertussis.
The child started receiving erythromycin (50 mg/kg) for 2 weeks and was
released from the hospital in good condition. Family members were retested
for pertussis and the results were negative (Table
1). On follow-up, the child did well, without signs of recurrence.
Comment
To the best of our knowledge, this is the first reported case of
azithromycin treatment failure for B pertussis. Although steroid
administration may have played a role, the reason for the treatment failure
is not clear. The B pertussis strains retrieved from the patient and
family were sensitive to azithromycin (Kirby-Bauer Disk-Diffusion method).
Because the pulsed-field gel electrophoresis strain differentiation
technique was not available, it is not clear whether the reinfecting B
pertussis was of the same strain. The short time (3 weeks) between the
first admission and the second points to the lack of eradication of the B
pertussis bacteria from the first infection. The adults in the family
were treated for pertussis, and cultures obtained tested negative for
organisms at the second episode; therefore, the family members were not
likely to be the origin of reinfection. The azithromycin dose given to the
child and family was 10 mg/kg. A higher dose may be necessary to prevent the
possibility of eradication failure. It seems that long-term erythromycin
should still be considered as the treatment of choice for pertussis in
infants. The relatively small sample sizes and lack of depth of existing
clinical trials portends the need for additional investigations comparing
new macrolides with erythromycin for treatment of pertussis in infants.
Jordan M. Steinberg, MSc
Haifa
Isaac Srugo, MD
Pediatric Infectious Diseases
Bnai Zion Medical Center
PO Box 4940
Haifa, Israel 31048
(e-mail: srugoi@tx.technion.ac.il)
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We thank Mihir Patel for his dedicated assistance in preparation of the
manuscript.
