Clinical and microbiological outcomes in patients with Streptococcus anginosus group bacteraemia identified through use of a rapid microarray assay

Abstract

Limited data exist evaluating outcomes in patients with serious Streptococcus anginosus group infections, particularly bacteraemia. A retrospective, single-centre cohort study was conducted to characterize potential risk factors along with clinical and microbiological outcomes in patients with S. anginosus group bacteraemia (SAGB). Adult inpatients with SAGB identified using the Verigene Gram-positive blood culture assay between March 2013 and April 2014 were included. Patients aged j18 or .89 years, those with SAGB identified at an outside facility and those who were incarcerated were excluded. Differences between groups were explored using a Wilcoxon rank-sum test, x 2 test, Student's t-test or Fisher's exact test as appropriate and a two-tailed P value of j0.05 was considered statistically significant. The 34 patients who met the inclusion criteria were 57¡14 (mean¡SD) years old and had a median Charlson co-morbidity index of 4 [interquartile range (IQR) 1-6] and 10 (29 %) were immunosuppressed at baseline. Almost half (47 %) had received antibiotics in the previous 90 days. Twelve (35 %) patients had gastrointestinal malignancies and the commonest source of bacteraemia was the gastrointestinal tract (53 %). The primary species responsible for SAGB was S. anginosus (68 %), and overall susceptibility to penicillin was 91 %. Patients were most often treated with a b-lactam/blactamase inhibitor combination (36 %) for a duration of 8 (IQR 4-13) days. Length of stay (LOS) and infection-related LOS were 10 (IQR 5-17) and 9 (IQR 4-12) days, respectively. Twenty [59 %] patients achieved a clinical cure, while 29 (85 %) achieved a microbiological cure. Four (12 %) patients died and one patient was readmitted within 30 days. In the largest cohort of patients with SAGB to date, gastrointestinal malignancies may have been an important risk factor for SAGB, while rapid identification via a microarray assay likely contributed to improved disease recognition and timely pharmacological and non-pharmacological therapy.

The Clinical View on Streptococcus anginosus Group – Opportunistic Pathogens Coming Out of Hiding

“…There is no gold standard for the identification of SAG. Cultivation methods and the available biochemical test are not sufficient for precise identification of the species, therefore it is necessary to use molecular techniques ( Wenzler et al, 2015 ; Kragha, 2016 ). Among them, two 16S rRNA real-time PCR assays were developed.…”

“…The authors revealed that the source of S. anginosus group infections is usually the gastrointestinal tract (GI). The study by Wenzler et al (2015) found 18 cases (53% of 34 patients) with a gastrointestinal source of bacteremia; therefore, sepsis could have originated from an unidentified source of the GI tract. Siegman-Igra et al (2012) reported 215 cases of SAG infections, the most common sources being the liver and other intraabdominal abscesses.…”

Streptococcus anginosus and Phalangeal Osteomyelitis: An Unusual Presentation

“…Chatelain et al corroborated these findings and also noticed a high number of radical reconstructive procedures (2/3) [ 4 ]. Regarding antibiotic choice, S. anginosus is almost always susceptible to penicillin and in most published literature beta-lactam antibiotics are the treatment of choice for SAG infections [ 7 , 15 ]. The adequate duration of antibiotic treatment has not been established yet.…”

“…Other additional circumstances that support the hematogenous spread of the infection are the patients' comorbidities. Hematogenous i n f e c t i o n s a r e p r e d o m i n a n t l y e n c o u n t e r e d i n immunocompromised and diabetics [9], and S. anginosus infections are mostly found in male adults with a history of cirrhosis, neoplasia, diabetes mellitus, and smoking [7,14,15]. The treatment of osteomyelitis consists of antibiotics, adequate surgical debridement, and bone fixation [2,9].…”

Aciduricity and acid tolerance mechanisms of <i>Streptococcus anginosus</i>

“…Further, iNOS upregulation has been detected in cancer tissues (Doi et al, 1999;Marrogi et al, 2000;Zhang et al, 1998) and could be a risk factor for carcinogenesis (Ambs et al, 1999;Giardiello et al, 1993;Iwasaki et al, 1997;Jadeski and Lala, 1999). Because the environments of these organs are generally mild acidic conditions (Fallingborg, 1999;Hassen et al, 2015;Khutoryanskiy, 2015;O'Hanlon et al, 2013), the aciduricity of S. anginosus can be a pathogenicity trait, allowing the microorganism to promote infection in an acidic condition followed by an aberrant infection at other body sites, or systemic infections (Mak et al, 2011;Shah et al, 2017;Wenzler et al, 2015).…”