Taking oral antibiotics to treat acne tripled a patient’s risk of developing pharyngitis, according to a study published online Nov. 21 in Archives of Dermatology.
However, using topical antibiotics for acne had no such effect, said Dr. David J. Margolis of the department of dermatology and the department of epidemiology and biostatistics, University of Pennsylvania, Philadelphia, and his associates.
Previous retrospective cohort studies and cross-sectional studies have noted an association between acne therapy with oral antibiotics and pharyngitis, but no prospective study has examined the issue until now. Dr. Margolis and his colleagues conducted one cross-sectional study involving 266 patients seen on a single occasion and one prospective longitudinal study involving 579 different patients seen over the course of a school year.
In the cross-sectional study, male and female graduate and postgraduate students (mean age 21 years) reported whether they were currently using antibiotics for acne and whether they had pharyngitis, currently or within the preceding month, that was severe enough to warrant a visit to a health care provider.
Of the 15 students who said they were taking oral antibiotics for acne, 10 (66.7%) had current or recent pharyngitis, compared with 82 of the 251 students (32.7%) who were not taking oral antibiotics.
Thus, the rate of pharyngitis was more than twice as high among subjects taking oral antibiotics as among those who weren’t taking the drugs in the cross-sectional study.
In the prospective longitudinal study, male and female students (mean age also 21 years) reported during three survey periods whether they were taking antibiotics for acne and whether they had pharyngitis within the preceding month that was severe enough to warrant a visit to a health care provider.
A total of 11.3% of subjects taking oral antibiotics reported having pharyngitis, compared with 3.3% of subjects who weren’t taking oral antibiotics for acne.
Thus, in the prospective longitudinal study, the rate of pharyngitis was more than 3 times higher among subjects taking oral antibiotics than the rate among those who weren’t taking them, the investigators said (Arch. Dermatol. 2011 Nov. 21 [doi:10.1001/archdermatol.2011.355]).
In contrast, rates of pharyngitis were not significantly higher among subjects using topical antibiotics for acne than among those not using any antibiotics.
Before conducting the two studies, Dr. Margolis and his associates had postulated that the use of oral antibiotics may have changed the microbial flora in the throat – for example, increasing pharyngeal colonization with group A streptococcus, "with a resulting increase in the frequency of symptomatic infection."
They proposed that the drugs may have acted by reducing the presence of less virulent organisms known to prevent colonization with group A strep, such as Streptococcus salivarius.
Contrary to that hypothesis, however, there was no association between pharyngeal colonization with either of those organisms and oral antibiotic use in the two studies.
The studies were limited in that they relied on students’ self reports both of antibiotic use and health care visits for pharyngitis; the student health clinic would not reveal the contents of students’ medical histories because of privacy concerns. In addition, the two studies may have missed some confounding risk factor that could be associated with both pharyngitis and antibiotic use, such as smoking status, the researchers said.
The National Institutes of Health supported the two studies. No financial conflicts of interest were reported.