"Presentation: A 16-year-old boy was referred to a hospital emergency department by his general practitioner after presenting with fever (39ºC), rigors and left-sided pleuritic chest pain.
Investigations and history: A chest x-ray showed left lower lobe pneumonia. The boy reported that he was allergic to amoxycillin and cephalosporins (as a child he had developed a rash to these agents). He had been taking daily doxycycline for the previous three months to treat mild acne, which had not responded to self-selected, over-the-counter preparations.
Management and course: He was treated with intravenous erythromycin because of his reported β-lactam allergies, but continued to be unwell, with ongoing fevers and rigors.
The day after admission, both sputum and blood cultures grew Streptococcus pneumoniae. After 48 hours, antibiotic sensitivity results showed that the isolate was intermediate-resistant to penicillin, and resistant to both erythromycin and tetracycline. The antibiotic treatment was changed to vancomcyin.
His fever resolved over the next 12 hours, and he made a slow but full recovery over the next week.
This patient developed a life-threatening infection with an antibiotic-resistant strain of S. pneumoniae. Because he was likely to be allergic to β-lactams, few options remained for therapy.
If not allergic to β-lactams, he could have been treated with intravenous penicillin, which remains effective therapy for pneumonia and septicaemia caused by S. pneumoniae strains with intermediate penicillin resistance.
Carriage of the resistant strain probably resulted from the long-term doxycycline therapy. Long-term use of any antibiotic for acne is likely to select resistant strains not only of Propionibacterium acnes, but also of other bacteria carried by the patient. Because doxycycline is broad-spectrum, its use helps select strains resistant to other antibiotics, such as erythromycin.
Mild to moderate acne can usually be successfully treated with combined topical therapy with benzoyl peroxide and retinoic acid, after discussion with a GP on optimal application.21 Antibiotics should not be prescribed unless absolutely necessary."
Medical Journal of Australia, Sept 2002