Acidosis associated with dietotherapy of maple syrup urine disease

Abstract

carditis? The negative culture may result from inoculation of clinical specimens onto media which do not support the growth of certain fastidious bacteria. Nutritionally deficient streptococci have recently been recognized to be responsible for some cases of culture-negative endocarditis. Although the incidence of infections produced by these bacteria is unknown, nutritionally deficient streptococci must be considered by the clinician and xhe clinical microbiologist in patients who present with evidence of endocarditis but with sterile blood cultures. It is unlikely that such bacteria will be recovered in standard blood culture flasks utilized in most hospitals. For the isolation of such streptococci from blood cultures, media must contain L-cysteine -~ or be supplemented with 0.001% pyridoxal H C l or 0.01% pyridoxamine dihydrochloridel; these growth factors are readily available. Nutritionally deficient streptococci exhibit variable susceptibility to penicillin G. Isolates may be susceptible to penicillin G when tested in unsupplemented media, but resistant to this antibiotic when media supplemented with 0.001% pyridoxal HC1 are employed? Penicillin alone may be ineffective in endocarditis due to these streptococci, but the combination of penicillin G and streptomycin may be synergistically effective in such infections? Since susceptibi l i t f testing in unsupplemented media may be inaccurate, therapy with a combination of penicillin G and streptomycin should be administered until sensitivity testing in appropriately supplemented media can be performed.