Upper respiratory tract infection in Thai adults: prevalence and prediction of bacterial causes, and effectiveness of using clinical practice guidelines.

BACKGROUND Antibiotics are over-prescribed for Upper Respiratory tract Infection (URI). Uncertainty in differentiating bacterial from viral infection is the main reason for this practice. More evidence is needed to encourage proper use of antibiotics for URI. OBJECTIVES 1) To determine the prevalence of Group A beta-hemolytic Streptococci (GAS) in adults with URI and clinical features associated with GAS infection. 2) To evaluate the effectiveness of management of adults with URI using the Clinical Practice Guideline (CPG). MATERIAL AND METHOD A prospective study was conducted on adult out-patients with URI at Siriraj Hospital from April to October 2004. Throat swab cultures were performed in all participants. Patients were assessed and managed according to CPG adapted from principles of appropriate antibiotic use for treatment of acute upper respiratory tract infections in adults endorsed by the Centers for Disease Control and Prevention, USA. Clinical outcomes were evaluated by telephone interviews. RESULTS Out of 292 patients enrolled, 55.5% had non-specific URI/common cold, 32.2% had pharyngitis/ tonsillitis, 11% had acute bronchitis and only 1.4% had acute sinusitis. The overall prevalence of GAS infection was 7.9%. GAS was isolated in 16% of the patients with pharyngitis/tonsillitis; and only 3.7% and 3.1% of the patients with non-specific URI/common cold and acute bronchitis respectively. Clinical manifestations associated with GAS were: 1)fever (T > or = 37.8 C), 2) exudate on the pharynx or tonsil, 3) tender cervical lymphadenopathy, and 4) absence of cough. The presence of < or = 3 of 4 criteria had high negative predictive value of 94.2%. None of the patients with non-specific URI/common cold, acute bronchitis and acute sinusitis had > or = 3 of 4 criteria. The clinical responses were not significantly different between those who received or did not receive antibiotics. Most of the patients had good clinical response by day 7. CONCLUSION The prevalence of GAS infection in adults with URI was 7.9%. The clinical features of T > or = 37.8 C, exudate on pharynx or tonsil, tender cervical lymphadenopathy, and absence of cough were significantly found in the patients with GAS infection. Management of adults with URI using the CPG was effective and safe.