Do the beta-hemolytic non-group A streptococci cause pharyngitis?

Implication of the beta-hemolytic non-group A streptococci (BHNAS) as pharyngeal pathogens has been based predominantly on reports of a few outbreaks, small case clusters, and anecdotes. These organisms have long been noted to constitute a significant number of the beta-hemolytic streptococcal isolates from throats of symptomatic and asymptomatic patients in a variety of populations. Laboratory studies have demonstrated the usefulness of anaerobic atmosphere and prolonged incubation in maximizing isolation of the BHNAS. More recently, genetic studies have furthered our appreciation of the taxonomy and have defined two major groups: Streptococcus anginosus-milleri group and large-colony BHNAS; the latter can be further separated on the basis of serogrouping and biotyping. Recognition of this diversity gives justification to the reexamination of the epidemiology and disease course of BHNAS pharyngitis. Treatment studies will also be required if all or subsets of these organisms can be confirmed as pharyngeal pathogens.