The pyogenic potential of the different Streptococcus anginosus group bacterial species: retrospective cohort study

Abstract

Streptococcus anginosus Group (SAG) bacteria are common causes of pyogenic infections (PIs). We examined the association between SAG species and the presence of a PI through a retrospective, observational, cohort study, between the years 2009 and 2015. All adults with clinically significant SAG infections in one hospital in Israel were assessed for association between SAG species and the presence of a PI defined as an abscess, empyema, or deep/organ space surgical site infection. Risk factors for PI were assessed using multivariate backward stepwise logistic regression analysis. We identified 263 patients with significant SAG infections, 182 (69%) of which were caused by S. anginosus, 45 (17·1%) by S treptococcus constellatus and 36 (13·7%) by S treptococcus intermedius. The mean age of the patients was 56·8 ± 19·1 years. PIs were identified among 160 (60%) of the patients and were mostly non-bacteraemic (147/160, 91·8%), while most non-PI patients had bacteraemia (70/103, 68%). S. anginosus and S. constellatus were associated with a significantly lower incidence of PI than S. intermedius, OR 0·18 (95% CI 0·06-0·53) and 0·14 (0·04-0·48), respectively. Patients with PI were younger and, in general, had less co-morbidities. S. intermedius was associated with pyogenic non-bacteraemic infections, while S. anginosus and S. constellatus were associated with bacteraemia with no abscess or empyema formation. These data may indicate differences in virulence mechanisms of these SAG bacteria.

From Normal Flora to Brain Abscesses: A Review of Streptococcus intermedius

“…Similarly, Kobo et al (2017) reported greater S. intermedius isolation from pyogenic infections (86.1%, n = 31) as compared to non-pyogenic infections (13.9%, n = 5). Another study correlated specific body sites with S. intermedius infection which prominently affected the central nervous system (62.1%, n = 18), followed by abdominal or pelvic sites (13.8%, n = 4), skin, soft tissues, bone (13.8%, n = 4), and head and neck infections (10.3%, n = 3) (Whiley et al, 1992).…”

Complicated Pneumonia With Empyema Caused by Streptococcus Anginosus in a Child

“…5 They are associated with abdominal, central nervous system, and pleuropulmonary infections; 6,7 S. anginosus is often found in blood cultures with or without identification of the primary site of infection. 5,8 Importantly, while S. anginosus is increasingly recognized as a significant cause of pulmonary infections in adults, studies reporting its identification in the pediatric population are rare.…”

The competence system of Streptococcus anginosus and its use for genetic engineering

“…The Streptococcus anginosus group (SAG) consists of three species, Streptococcus anginosus , Streptococcus constellatus and Streptococcus intermedius . Although bacterial species of this group are commensals residing on mucosal membranes of the oral cavity, the gastrointestinal and the urogenital tract, they have been increasingly isolated from invasive infections in recent years . Difficulties to cultivate and identify the SAG correctly at the species level contributed to a misinterpretation of their pathogenic potential in older investigations .…”