Streptococcal infections diagnosis

As streptococcal cellulitis is indistinguishable clinically from staphylococcal cellulitis, administration of a semisynthetic penicillin (nafrillin or oxacillin) or first-generation cephalosporin (cefazolin) is recommended until a definitive diagnosis, by skin or blood cultures, can be made (Table 47-4). If documented to be a mild cellulitis secondary to streptococci, oral penicillin VK, or intramuscular procaine penicillin may be administered. More severe streptococcal infections should be treated with IV antibiotics (such as ceftriaxone 50 to 100 mg/kg as a single dose). 

Agglutination reactions have many applications in clinical medicine that can be used to type blood cells for transfusion, to identify bacterial cultures, and to detect the presence and relative amount of specific antibody in a patient s serum. For example agglutination of antibody-coated latex beads has become a popular commercial method for the rapid diagnosis of various conditions such as pregnancy and streptococcal infections. 

Choice of antimicrobial follows automatically from the clinical diagnosis because the causative organism is always the same, and is virtually always sensitive to the same drug, e.g. meningococcal septicaemia (benzylpenicillin), some haemolytic streptococcal infections, e.g. scarlet fever, erysipelas (benzylpenicillin), typhus (tetracycline), leprosy (dapsone with rifampicin). 

Guarner J, Sumner J, Paddock CD, et al. Diagnosis of invasive group A streptococcal infections by using immunohistochemical and molecular assays. Am J Clin Pathol. 2006 126 148-155. 

Apart from this modest, localized form, a generalized skin condition is observed in rare cases, as well as systemic forms with endocarditis. Differential diagnosis must be made with erysipelas, a febrile streptococcal infection with a rapid extension. The disease does not leave any immunity and re-infection is therefore possible. The bacteria responsible can be cultured from bioptic cells obtained from the margins of the lesion or from the blood in systemic forms. The disease can be treated with penicillin or tetracycline for 1 week. 

Barnham M, Kerby J, Skillin J (1980) An outbreak of streptococcal infection in a chicken factory. J Hyg Camb 84 71-75 Bennet JH (1975) The false positive diagnosis skin disorders that mimic an occupational dermatitis. Cutis 15 410-411... 

Bisno AL, Gerber MA, Gwaltney JM Jr, et al. Practice guidelines for the diagnosis and management of group A streptococcal pharyngitis. Infectious Diseases Society of America. Clin Infect Dis 2002 35(2) 113-125. 

Kaplan, E.L. (1971) Diagnosis of streptococcal pharyngitis differentiation of active infection from carrier state in the symptomatic child. J Infect Dis 123 490-501. 

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