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2007 OMIG, Abstract 2

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TheRise and Fall of  Antibiotic Resistance in Pneumococcus after Mass Azithromycin Distributions for Trachoma
Sara Haug1,2, Vicky Cevallos1, Jenafir House1, Wondu Alemayu4, Takele Lakew4, Tina Rutar1,3, Jack Whitcher1,3, Bruce Gaynor1,3, Tom Lietman1,3 and the TEF trachoma team in Ethiopia (1: F.I. Proctor Foundation, UCSF, 2: UCSF School of Medicine, 3: Department of Ophthalmology, UCSF, 4: Orbis-Ethiopia)

Purpose:  To determine whether mass azithromycin distributions to treat Chlamydia trachomatis induce
resistance in Streptococcus pneumoniae, and to assess whether resistance declines after antibiotics are discontinued.
Methods:  The study was part of a village-randomized clinical trial in Ethiopia to evaluate efficacy of biannual mass azithromycin treatment for trachoma.  All individuals over 1-year of age were treated with a single dose of azithromycin.   Nasopharyngeal swabs were collected in 15 random children in each of 8 villages, 6 months after the 4th and 6th mass distribution, and 12-months after the 6th distribution.  Control samples were obtained in untreated villages randomly chosen from the same area.  All swabs were cultured for the presence of S. pneumoniae.  MIC tests were performed on S. pneumoniae isolates to establish the resistance profile to six different antibiotics. 
Results:  Untreated villages had 91% S. pneumoniae carriage and treated villages had 90% carriage on average.  Resistance in untreated villages was <1%.  Azithromycin resistance in treated villages was 27.9% after the 4th treatment, 74.7% after the 6th treatment, and 30.6% 12-months after the 6th treatment.  There was a mild increase in tetracycline resistance, but no significant change with other antibiotics.
Conclusions: The WHO recommends annual mass azithromycin distributions to treat infectious trachoma, and to date no detectable resistance has been seen in chlamydia.  Biannual mass distributions do generate significant pneumococcal resistance to macrolides.  Fortunately, our results suggest that this resistance is transient, and restricted to a class of antibiotics not frequently used in this area.  Since chlamydial infection has been nearly eliminated with these treatments, the benefits of mass azithromycin administration appear to far outweigh the negative aspects of treatment.

Grant support: That Man May See, the Osher Foundation, NIH-NIAID R21 AI 55752, the International Trachoma Initiative, the Bodri Foundation, Research to Prevent Blindness, and the Harper Inglis Trust.


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