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Query: UMLS:C0014118 (endocarditis)
 15,629 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The viridans streptococci are a heterogeneous group of organisms frequently associated with microbial endocarditis. Isolates from consecutive patients with endocarditis due to viridans streptococci who were seen at The New York Hospital from 1944 to 1955 and from 1970 to 1978 were speciated, and the relative frequencies and patterns of sus ceptibility to penicillin were determined. Vitamin B6-dependent streptococci, classified as Streptococcus mitior, accounted for 5%-6% of microbial endocarditis in both time periods. Since these nutritional variants require the active forms of vitamin B6 for growth in routein media, they can be responsible for culture-negative endocarditis. Media must be supplemented with either pyridoxal hydrochloride or pyridoxamine dihydrochloride (the active forms of vitamin B6) for isolation, identification, and subsequent testing of susceptibility to antimirobial agents. Pyridoxine hydrochloride does not support the growth of these organisms in vitro.
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PMID:Viridans streptococcal endocarditis: the role of various species, including pyridoxal-dependent streptococci. 55 16

Vitamin B6-dependent viridans streptococci were isolated from two patients with microbial endocarditis. Because of their unique requirement for pyridoxal hydrochloride, these organisms did not grow normally in the media usually used in diagnostic laboratories. When tested in supplemented media, both strains were resistant to penicillin G and relatively sensitive to streptomycin. Penicillin-streptomycin synergy was demonstrated in vitro as well as in experimental endocarditis. These laboratory findings confirmed the clinical observations in these two patients that penicillin-streptomycin therapy should be used in vitamin B6-dependent streptococcal endocarditis. Nutritionally varient streptococci may be important pathogens in microbial endocarditis and must be considered in patients with suggestive clinical findings but negative blood cultures.
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PMID:Antimicrobial therapy of vitamin B6-dependent streptococcal endocarditis. 88 95