Aetiology of acute pharyngitis: the role of atypical bacteria

In order to establish the role of atypical bacteria and compare characteristics of different infectious agents in acute pharyngitis, 127 patients with acute pharyngitis (66 males; median age, 5.33 years; range, 6 months to 14 years) and 130 healthy subjects of similar sex and age were studied. Serology with paired samples and PCR on nasopharyngeal aspirates and throat cultures were used to identify bacteria and viruses. Viruses were identified in 43 patients (33.8%) and five controls (3.8%; P < 0.0001), potential bacterial pathogens in 34 patients (26.8%) and 26 controls (20%; P = 0.256) and mixed viral/bacterial pathogens in 26 patients (20.5%) and none of the controls (P < 0.0001). The main aetiological agents were adenovirus, respiratory syncytial virus (RSV), Mycoplasma pneumoniae, Streptococcus pyogenes and Chlamydia pneumoniae. M. pneumoniae was the agent found most frequently as a single pathogen. A history of recurrent pharyngitis, having older siblings and a negative outcome were significantly more common among patients with acute M. pneumoniae infection than among those with infections due to other pathogens or healthy controls. This study demonstrates that: (i) adenovirus and RSV have a prominent role in acute pharyngitis; (ii) S. pyogenes is found frequently, but it is not possible to distinguish simple carriers from patients with a true infection; (iii) M. pneumoniae appears to be able to cause acute pharyngitis per se; and (iv) C. pneumoniae seems to be mainly a co-pathogen. To avoid the risk of an incorrect therapeutic approach, simple laboratory investigations that allow rapid identification of M. pneumoniae infections are urgently needed.