Chapter 42: Infections: Bacterial & Spirochetal

BACTERIAL INFECTIONS

GROUP A STREPTOCOCCAL INFECTIONS

General Considerations

Group A streptococci (GAS) are common gram-positive bacteria producing a wide variety of clinical illnesses, including acute pharyngitis, impetigo, cellulitis, and scarlet fever. GAS can also cause pneumonia, septic arthritis, osteomyelitis, meningitis, and other less common infections. GAS infections may also produce postinfectious sequelae (rheumatic fever and poststreptococcal glomerulonephritis [PSGN]).

Almost all GAS are β-hemolytic. These organisms may be carried without symptoms on the skin and in the pharynx, rectum, and vagina. All GAS are sensitive to penicillin. Resistance to erythromycin is common in some countries and has increased in the United States.

Prevention

GAS pharyngitis usually occurs after contact with respiratory secretions of a person infected with GAS. Crowding facilitates spread of GAS and outbreaks of pharyngitis and impetigo occur. Prompt recognition and institution of antibiotics may decrease spread. Treatment with antibiotics prevents acute rheumatic fever.

Clinical Findings

A. Symptoms and Signs

1. Ear/nose/throat infections

The onset is insidious, with mild symptoms (low-grade fever, serous nasal discharge, and pallor). Otitis media is common. Exudative pharyngitis and cervical adenitis are uncommon in this age group.

Classic GAS pharyngitis presents with the sudden onset of fever, sore throat, headache, malaise, abdominal pain, and often vomiting. On examination, tonsillar exudate and tender anterior cervical adenopathy are usually noted. Petechiae are frequently seen on the soft palate.

2. Scarlet fever

In scarlet fever, the skin is diffusely erythematous and appears sunburned and roughened (sandpaper rash); most intense in the axillae, groin, and on the abdomen and trunk. It blanches except in the skin folds, which do not blanch and are pigmented (Pastia sign). The rash usually appears 24 hours after the onset of fever and rapidly spreads over the next 1–2 days. Desquamation begins on the face at the end of the first week and becomes generalized by the third week. Early in the infection, there is circumoral pallor and the surface of the tongue is coated white, with the papillae enlarged and bright red (white strawberry tongue). Subsequently desquamation occurs, and the tongue appears beefy red (strawberry tongue). Petechiae may be seen on any mucosal surfaces.