Streptococcus viridans infections

This patient was treated empirically with vancomycin alone because his physicians suspected that he had endocarditis, caused by Streptococcus of the viridans group. The history indicated that the origin of the infection was the patient s mouth. Three days later the results from the clinical microbiology laboratory showed that three blood cultures, taken at the time of admission, grew Enterococcus faecalis. susceptible to ampicillin, vancomycin, gentamicin, and streptomycin. 

In addition to S. pneumoniae, the viridans group of streptococci is also developing resistance to penicillin through the same mechanism, altered penicillin-binding proteins. In contrast, resistance has not developed in Streptococcus pyogenes, and both penicillins G and V are antibiotics of choice for systemic infections caused by this organism. 

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