Chapter 130. Streptococcal and Enterococcal Infections (Part 13) Infection with Viridans Streptococci: Treatment Isolates from neutropenic patients with bacteremia are often resistant to penicillin; thus these patients should be treated presumptively with vancomycin until the results of susceptibility testing become available. Viridans streptococci isolated in other clinical settings usually are sensitive to penicillin. Abiotrophia Species (Nutritionally Variant Streptococci) Occasional isolates cultured from the blood of patients with endocarditis fail to grow when subcultured on solid media. These nutritionally variant streptococci require supplemental thiol compounds or active forms of vitamin B 6 (pyridoxal or pyridoxamine) for growth in the laboratory. The nutritionally variant streptococci are generally grouped with the viridans streptococci because they cause similar types of infections. However, they have been reclassified on the basis of 16S ribosomal RNA sequence comparisons into a separate genus, Abiotrophia, with two species: A. defectivus and A. adjacens. Infection with Nutritionally Variant Streptococci: Treatment Treatment failure and relapse appear to be more common in cases of endocarditis due to nutritionally variant streptococci than in those due to the usual viridans streptococci. Thus the addition of gentamicin (1 mg/kg every 8 h for patients with normal renal function) to the penicillin regimen is recommended for endocarditis due to the nutritionally variant organisms. Other Streptococci S. suis is an important pathogen in swine and has been reported to cause meningitis in humans, usually in individuals with occupational exposure to pigs. Strains of S. suis associated with human infections have generally reacted with Lancefield group R typing serum and sometimes with group D typing serum as well. Isolates may be α- or β-hemolytic and are sensitive to penicillin. S. iniae, a pathogen of fish, has been associated with infections in humans who have handled live or freshly killed fish. Cellulitis of the hand is the most common form of human infection, although bacteremia and endocarditis have been reported. Anaerobic streptococci, or peptostreptococci, are part of the normal flora of the oral cavity, bowel, and vagina. Infections caused by the anaerobic streptococci are discussed in Chap. 157. Further Readings Bisno AL et al: Practice guidelines for the diagnosis and management of group A streptococcal pharyngitis. Clin Infect Dis 35:113, 2002 [PMID: 12087516] ——— , Stevens DL: Streptococcal infections of skin and soft tissues. N Engl J Med 334:240, 1996 Carapetis JR et al: The global burden of group A streptococcal diseases. Lancet Infect Dis 5:685, 2005 [PMID: 16253886] Centers for Disease Control and Prevention: Prevention of perinatal group B streptococcal disease. MMWR 51(RR-11):1, 2002 Gassas A et al: Predictors of viridans streptococcal shock syndrome in bacteremic children with cancer and stem- cell transplant recipients. J Clin Oncol 22:1222, 2004 [PMID: 15051769] Gibbs RS et al: Perinatal infections due to group B streptococ ci. Obstet Gynecol 104:1062, 2004 [PMID: 15516403] Jackson LA et al: Risk factors for group B streptococcal disease in adults. Ann Intern Med 123:415, 1995 [PMID: 7639440] Kauffman CA: Therapeutic and preventative options for the management of vancomycin- resistant enterococcal infections. J Antimicrob Chemother 51(Suppl3):iii23, 2003 Kaul R et al: Intravenous immunoglobulin therapy for streptococcal toxic shock syndrome— a comparative observational study. The Canadian Streptococcal Study Group. Clin Infect Dis 28:800, 1999 [PMID: 10825042] The Prevention of Invasive Group A Streptococcal Infections Workshop Participants: Prevention of invasive group A streptococcal disease among household contacts of case patients and among postpartum and postsurgical patients: Recommendations from the Centers for Disease Control and Prevention. Clin Infect Dis 35:950, 2002 Bibliography Working Group on Severe Streptococcal Infections: Defining the group A streptococcal toxic shock syndrome: Rationale and consensus definitions. JAMA 269:390, 1993 . Chapter 130. Streptococcal and Enterococcal Infections (Part 13) Infection with Viridans Streptococci: Treatment Isolates. Invasive Group A Streptococcal Infections Workshop Participants: Prevention of invasive group A streptococcal disease among household contacts of case patients and among postpartum and postsurgical patients:. Control and Prevention. Clin Infect Dis 35:950, 2002 Bibliography Working Group on Severe Streptococcal Infections: Defining the group A streptococcal toxic shock syndrome: Rationale and consensus