The Streptococcus anginosus group Often underestimated, unrecognized, and misidentified lassification, C, F or G and collectively nomenclature and referred to as the “Streptococcus Cidentification of the milleri” group. Unification of Streptococcus anginosus group these streptococci into a single (SAG) have been historically species, Streptococcus problematic and unreliable, anginosus, was later proposed, By Kerry Pierce, MS mainly due to variability in as this is the oldest approved bacteriological characteristics name for members in this group and clinical presentations. and, therefore, took precedence over the name “milleri.” Kerry Pierce is a Technical SAG was first discovered in Support Representative at 1956 by Guthof, when More recent molecular analysis Hardy Diagnostics. examining non-hemolytic shows three discrete DNA streptococcal species isolated homologies within SAG, She earned her Bachelor’s and Master’s Degrees at from oral infections. This group corresponding to three distinct Florida State University in included an assortment of strains: StreptococcusTallahassee. anginosusHer studies streptococci associated with were focused on molecular serious pathogenic infections. □ Streptococcus constellatus microbiology.Classification, nomenclature □ Streptococcus intermedius and identification of the Lancefield group reaction, along □ Streptococcus anginosus StreptococcusBefore joining anginosus Hardy, Kerry group with other common laboratory (SAG)held severalhave been college historically level techniques used problematicteaching positions and unreliable, for to identify “In general, members of SAG have a biology and microbiology. mainly due to variability in bacteria, are propensity to form abscesses and cause bacteriological characteristics inconsistent Kerry takes pride in serving invasive pyogenic infection, including head andand clinical assisting presentations. customers Thisat throughout the S. groupHardy was Diagnostics first discovered and has in anginosus group, and neck infection, brain abscesses, intra‐ 1956become by Guthof, involved in inreference various to making it thoracic and intra‐abdominal infections.” non-hemolyticwriting and training streptococcal difficult to assignments. classify these microorganisms. The species Members of this group are name, “milleri,” was chosen in phenotypically characterized honor of the microbiologist, by their microaerophilic or W.D. Miller, but was later anaerobic growth amended to include small beta- requirement, the formation of hemolytic, along with non- pin-point or “minute” sized hemolytic streptococci in groups colonies, and the frequent presence of a distinctive produce extracellular enzymes Head and neck infection by caramel-like smell when capable of degrading connective SAG is generally associated cultured on a solid agar tissue, including hyaluronidase, with dental origin and the medium. deoxyribonuclease, majority of these patients ribonuclease, gelatinase and usually require surgical Members of SAG are collagenase, may contribute intervention. Consequently, considered normal commensal greatly to their overall odontogenic infection cannot be flora in humans and are pathogenicity. ruled out in patients with SAG commonly isolated from the bacteremia of unknown source, oral cavity, oropharynx, The Streptococcus anginosus especially in patients with poor gastrointestinal tract and vagina. group is also known to release dental hygiene. However, these bacteria possess extracellular products that have the potential to cause a variety an immunosuppressive effect, of multiple body site infections further permitting them to in both human and animal hosts. survive and flourish within the confines of an abscess. After their initial isolation from oral infections, subsequent research on SAG confirmed their role in pathogenic oral and teeth infections, as well as their carcinogenic potential. Studies investigating the bacteriology of dental caries and abscesses show that members of SAG Figure 3: A CT scan of a SAG Figure 1: Streptococcus have been isolated from dental brain abscess from an 8 year old constellatus is a Group C beta aspirates, with some patients presenting with fever and hemolytic strep forming small showing nearly pure colony headache for one month. colonies on Blood Agar. It is a growth of SAG, while others member of the Streptococcus have a majority of SAG mixed anginosus group (SAG). Chronic alcohol consumption is with other oral anaerobes. a major risk factor for cancers Unlike other types of viridans of the upper digestive tract. In streptococci, members of SAG fact, the incidence of esophageal are oftentimes associated with cancer in alcoholics is bacteremia and abscess reportedly much higher than as formation; in general, treatment seen in the general population, of abscesses requires surgical suggesting the presence of intervention and drainage. The certain risk factors in chronic pathogenic mechanisms of this alcohol consumption-related group are not well known or carcinogenesis. Recent research completely understood, but it is into the concentration of S. widely believed that the anginosus present in the saliva presence of a polysaccharide of alcoholics compared to capsule helps these healthy patients or patients with opportunistic pathogens evade other types of chronic the body’s natural defense oral/digestive diagnoses systems and escape (esophageal cancer, phagocytosis prior to infection. periodontitis, gastritis, etc.) In addition, their ability to Figure 2: SAG is a common cause shows elevated levels of S. of dental abscesses. anginosus in the saliva of alcoholics, suggesting they have were recovered from blood. S. a higher than average risk for S. intermedius and S. constellatus anginosus infection. are more likely to cause abscesses than S. anginosus, In general, members of SAG while S. constellatus and S. have a propensity to form anginosus appear more likely to abscesses and cause invasive be polymicrobial. Previous pyogenic infection, including research also suggests that, head and neck infection, brain although S. intermedius is the abscesses, intra-thoracic and least commonly isolated intra-abdominal infections. species, it appears to be the Predisposing or underlying most pathogenic in terms of the conditions noted with infection etiology of disease. by SAG include previous surgery, trauma, diabetes, Other than pyogenic infection, immunodeficiency, and infective endocarditis has been In conclusion, members of malignancy, but may also be reported in a significant number SAG have a tendency to cause related to hygiene or the of patients with SAG abscess formation, but patient’s overall general health bacteremia; however, the condition as outlined above. incidence of infective different species have a endocarditis appears to be different propensity for declining. Current literature pyogenic infection. Therefore, suggests that endocarditis since the three species of SAG caused by beta-hemolytic are associated with different streptococci and SAG show that clinical manifestations and the majority of patients with symptoms, it is useful to SAG endocarditis also appear to identify these microorganisms in order to further investigate have underlying complications the etiology of disease and due to pre-existing heart optimize patient outcomes. diseases. Among the species of streptococci in the Streptococcus anginosus group, it is believed that S. anginosus is the most likely member to cause endocarditis. Studies using mouse models support the Figure 4: A gingival abscess finding that S. anginosus is more likely to cause Different species of SAG appear endocarditis, because this at differing rates and of different species is generally found in Figure 5: Hardy’s Rapid degrees of pathogenicity. higher cell densities within Anginosis ID Kit performs an Research shows that S. infected tissue. arginine decarboxylase (positive constellatus and S. anginosus seen in the second tube) and a are isolated at roughly the same Voges-Proskauer test (positive frequency from clinical seen in the fourth tube) to quickly specimens, but at a rate four place a strep within the anginosus times more often than S. group. intermedius. The majority of isolates were recovered from Consequently, Hardy exudates, aspirate or fluid Diagnostics has developed the samples, and additional isolates Rapid Anginosus Kit (Cat. no. identification of streptococcal usually harmless members of Z14) which can be used to isolates suspected of belonging the viridans streptococci. detect arginine decarboxylase to the anginosus group. This kit activity and perform the Voges- offers a simple method to Kerry Pierce, MS Proskauer test in as little as four quickly distinguish the possibly Santa Maria, California hours, to assist in the pathogenic SAG from the other .