Arcanobacterium haemolyticum and streptococcal pharyngitis.

Arcanobacterium haemolyticum was recovered from 0.5% of throat cultures of 3,922 patients seeking medical attention because of sore throat. Most of the patients positive for A. haemolyticum were 15-25 years old, and had fever (80%), lymphadenopathy (67%), pharyngeal exudate (69%) or skin rash (23%). In this age group, 2% of the throat cultures proved positive for A. haemolyticum. All A. haemolyticum strains were susceptible to penicillin, erythromycin, cephalexin and clindamycin, but resistant to trimethoprim/sulphamethoxazole. In half of the patients with A. haemolyticum it was the only bacterial pathogen isolated, while in the remainder, beta-haemolytic streptococci were also detected. As expected, beta-haemolytic streptococci were much more frequent than A. haemolyticum in the throat cultures.