Viridans-group streptococcal infections in immunocompromised hosts

Viridans streptococci, a diverse group of streptococcal species, are important causes of sepsis and pneumonia in the neutropenic host and sepsis and meningitis in the neonate. The oral mucosa is the most common portal of entry. Among the factors that predispose to development of viridans streptococcal sepsis are: profound neutropenia; mucositis, especially oral mucositis; cytarabine (Ara-C) therapy, which seems to have an effect beyond its association with mucositis; young age; and trimethoprim-sulphamethoxazole or quinolone administration. Fever is usually more than 39 degrees C and prolonged for several days even though blood cultures are typically negative after 24 h of therapy. The majority of patients recover uneventfully if appropriate therapy is initiated early. However, fulminant septic shock may occasional occur at onset. Delayed shock 2 or 3 days after presentation may also occur despite administration of microbiologically effective antibiotics. In severe cases, adult respiratory distress syndrome may be manifested two or three days after the initial bacteremia. There is considerable variability among institutions, but the median death rate associated with viridans streptococcal sepsis is about 10%. Local susceptibility patterns should be used to guide initial therapy for suspected viridans streptococcal infections. Some isolates of viridans streptococci are resistant to penicillins and cephalosporins, in which case vancomycin is preferred. Recurrence during subsequent neutropenic episodes is not unusual.