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Role of beta-hemolytic group C streptococci in pharyngitis: incidence and biochemical characteristics of Streptococcus equisimilis and Streptococcus anginosus in patients and healthy controls.

The biochemical characteristics and the isolation rates of the two Lancefield group C streptococcal species (S. equisimilis and S. anginosus) from patients with pharyngitis and asymptomatic controls were compared. Some 239 strains of beta-hemolytic group C streptococci were isolated from 1,480 patients (209 strains) with pharyngitis and 227 controls (30 strains). A total of 44 strains displayed broad hemolysis, were Voges-Proskauer test negative, and produced glucuronidase. Some 72.7% of these strains also fermented ribose. A second group of 159 strains was Voges-Proskauer test positive and glucuronidase negative; 98.8% also displayed minute hemolysis and only 3.7% fermented ribose. These two groups represent typical large-colony S. equisimilis and small-colony S. anginosus, respectively. A small number of strains (36 in total) exhibited intermediate characteristics; morphologically, all 36 strains resembled S. anginosus, but 6 strains biochemically resembled S. equisimilis. No strains of S. equisimilis fermented sorbitol (unlike S. zooepidemicus) and all fermented trehalose (unlike S. equi). The structural carbohydrate profiles of S. equisimilis and S. anginosus both included galactosamine (consistent with their being group C organisms), but the profiles were not distinguishable. In total, 78.5% of strains from controls and 83.3% of strains from patients were determined to be the species S. anginosus. S. equisimilis was isolated from 3.0% of patients and 2.2% of controls, and S. anginosus was isolated from 11.1% of patients and 11.0% of controls. Thus, S. equisimilis and S. anginosus are both members of the normal flora of asymptomatic individuals. The incidence and biochemical characteristics of these two species are similar in patients who are healthy and those who have disease. However, a companion article provides clinical evidence associating S. equisimilis (but not s. anginosus) with pharyngitis.

Adult↗

Characteristics of Streptococcus milleri and Streptococcus mitior from infected dental root canals.

Morphological and physiological characteristics of 103 streptococcal isolates obtained from positive routine cultures of material from dental root canals at filling, were studied. The majority of the isolates were those which at a primary identification not fullfilled the criteria of enterococci, Strep. sanguis, Strep. mutans or Strep. salivarius. Only a few representative strains of the latter types were included in the study as a control of the method. The resemblance of the 103 isolates to 38 reference strains were assessed with numerical methods. The isolates formed 9 clusters with reference strains occurring in all but one. Of the isolates which it was intended to identify and characterize with numerical taxonomic analysis, all but one joined one of 3 clusters and were identified as Strep. milleri or Strep. mitior (mitis). The most useful cultural characteristics to dfferentiate the two species were growth on the sulphonamide containing MC-agar and 7.5% bile blood agar by Strep. milleri and production of hydrogen peroxide by Strep. mitior. The characteristics of the strains in the nine 80-phenons are given in Table 2. Other characteristics that appeared to be of interest for differentiating Strep. milleri from Strep. mitior and these two species from other viridans streptococci are underlined in Table 2. Strep. milleri seems not earlier to have been reported to occur in infected root canals. The occurrence of Strep. milleri is in agreement with the data given on serological groups found among streptococcal isolates from routine root canal cultures. Little is known about the occurrence and distribution of Strep. milleri in the human oral cavity, which therefore warrant further investigations.

Dental Pulp Cavity↗