Management of Group A [beta]-hemolytic streptococcal pharyngotonsillitis in children

Journal of Family Practice, Dec, 2006 by Itzhak Brook, Joseph E. Dohar

Acute pharyngotonsillitis is one of the most common infections encountered by pediatricians and family physicians. According to the US Vital Health Statistics report, acute pharyngotonsillitis is responsible for more than 6 million office visits each year by children younger than 15 years of age and an additional 1.8 million visits by adolescents and young adults aged 15 to 24 years. (1) Most children with acute pharyngotonsillitis have symptoms that can be attributed to infection with a respiratory virus, such as adenovirus, influenza virus, parainfluenza virus, rhinovirus, and respiratory syncytial virus. (2,3) However, in approximately 30% to 40% of cases, acute pharyngotonsillitis is of bacterial etiology. (4) Group A [beta]-hemolytic streptococci (GABHS) are responsible for most bacterial cases of acute pharyngotonsillitis, although other pathogens, such as Neisseria gonorrhoeae, Arcanobacterium haemolyticum, Mycoplasma pneumoniae, and Chlamydia pneumoniae, may be the causative agents in sporadic cases. (5) Pharyngotonsillitis caused by these latter pathogens can sometimes be distinguished from that caused by GABHS by considering the patient's medical history in concert with the clinical presentation. In some cases, acute pharyngotonsillitis may have an idiopathic etiology. An accurate diagnosis of GABHS infection is important because it is the only common form of acute pharyngotonsillitis for which antibiotic therapy is definitely indicated. (3) Antibiotic therapy can shorten the clinical course of GABHS pharyngotonsillitis, reduce the rate of transmission, and prevent suppurative and nonsuppurative complications, such as peritonsillar abscess and acute rheumatic fever. (2) Although the threat of rheumatic fever is much lower for children in the United States than in developing nations, preventing rheumatic fever and the spread of disease is the primary goal of antibiotic therapy in GABHS pharyngotonsillitis treatment and a cornerstone of practice guidelines.

Diagnosis of GABHS Pharyngotonsillitis

The presence of GABHS pharyngotonsillitis may be suspected on the basis of clinical findings, and the diagnosis should be confirmed by laboratory testing (FIGURE 1). (3,6) GABHS infections usually occur in children aged 5 to 15 years during the winter and early spring in temperate climates. Symptoms frequently include acute throat pain, severe pain on swallowing, and fever, but headache, nausea, vomiting, and abdominal pain may also be present, especially in younger children. Clinical examination shows tonsillopharyngeal erythema, sometimes with exudate, and tender, enlarged anterior cervical lymph nodes (lymphadenitis). Other findings may also be present, including a scarlatiniform rash and palatal petechiae. Unfortunately, these signs and symptoms are not specific for GABHS pharyngotonsillitis and consequently are not sufficient for making an accurate diagnosis. On the other hand, a viral rather than a bacterial etiology is strongly suggested by the absence of fever or by the presence of certain clinical features, such as conjunctivitis, cough, hoarseness, coryza, anterior stomatitis, discrete ulcerative lesions, viral exanthem, and diarrhea.

[FIGURE 1 OMITTED]

When GABHS pharyngotonsillitis is suspected, a laboratory test--either throat culture or rapid antigen detection test (RADT)--should be conducted to document the presence of GABHS in the pharynx and confirm the diagnosis. (3,6) The culture of a throat swab on a sheep blood agar plate remains the gold standard and, when properly performed, has a sensitivity of 90% to 95% for detecting GABHS in the pharynx. Because culture results are not available for at least 1 day, RADTs were developed to permit the more timely identification of GABHS on a throat swab. The RADTs detect a carbohydrate antigen unique to GABHS by enzyme, optical immunoassay techniques, or the presence of unique gene sequences by chemiluminescent DNA probes. Compared to throat culture, most available RADTs have a specificity of [greater than or equal to] 95%, making false-positive results unlikely. (3) Therapeutic decisions, therefore, can be made reliably from a positive RADT result. Rapid identification of GABHS permits earlier antibiotic therapy, thus reducing the risk of transmission and allowing children to return sooner to school. (2) However, the sensitivity of RADTs is in the range of 80% to 90%, which raises the possibility of false-negative results. Therefore, the Infectious Diseases Society of America (IDSA) recommends that negative RADT results in children and adolescents be confirmed with a throat culture, unless the physician has documented in his or her practice that the RADT that is being used provides results comparable to those provided by throat culture. (3)

Accurately diagnosing GABHS pharyngotonsillitis and treating with appropriate antibiotic therapy provides positive benefits, including prevention of complications such as acute rheumatic fever and tonsillar abscess, shortened clinical course, and decreased contagiousness. Conversely, improper diagnosis may result in negative consequences, including unnecessary antibiotic prescriptions that confer increased health care costs and contribute to the development of bacterial resistance, as well as adding the risk of adverse side effects, including allergic reactions from the antibiotic itself. (7)