Streptococcus milleriGroup Isolates from Blood Cultures: Consider Surgical Sepsis

Predicting bacteremia caused by Streptococcus anginosus group: A new scoring method

BACKGROUND

Viridans group streptococci (VGS) are the most common causative organisms of infective endocarditis. Among VGS, the Streptococcus anginosus group (SAG) is often associated with abscess formation, and delayed diagnosis leads to increased morbidity and mortality. This study aims to examine the factors associated with SAG bacteremia and develop a predictive scoring method.

METHODS

This single-center retrospective case-control study of patients with VGS bacteremia compared the background and clinical characteristics between the SAG and non-SAG groups. The univariate analysis used the χ² test and t-test. The multivariate analysis was conducted using logistic regression.

RESULTS

Out of 161 patients, 95 had SAG and 66 had non-SAG bacteremia. Age > 63 years: 2 points (odds ratio [OR] = 3.52, 95% confidence interval [CI]: 1.64-7.54); solid tumor: 2 points (OR = 4.44, 95% CI: 1.42-6.77); C-reactive protein > 7.61 mg/dL: 3 points (OR = 5.40, 95% CI: 2.49-11.72), and white blood cell count > 8550/μL: 2 points (OR = 2.76, 95% CI: 1.29-2.91) were found to be independently associated with SAG bacteremia. After totaling the above variables and adding 1 point for diabetes mellitus, the area under the receiver operating curve was 0.81 (95% CI: 0.74-0.88). The sensitivity and specificity were 51% and 88%, respectively, at a cut-off of 6 points.

CONCLUSIONS

In patients with VGS bacteremia, a score of 6 points or higher using this method predicts SAG with high specificity.

Multiple Hepatic Abscesses Secondary to Streptococcus anginosus Infection: A Case Report and Review of the Literature

Hepatic abscesses are rare and generally present as solitary lesions in immunocompromised patients. The development of multiple hepatic abscesses in an immunocompetent patient is relatively uncommon. We report a rare case of a 73-year-old woman who presented with fever and right upper quadrant abdominal tenderness. Laboratory findings were significant for leukocytosis, transaminitis, and elevated inflammatory markers. Peripheral blood culture grew Streptococcus anginosus. Computed tomography of the abdomen and pelvis (CT A/P) revealed multiple hypoattenuating ill-defined cystic lesions in the liver consistent with abscesses formation; this was confirmed by magnetic resonance cholangiopancreatography (MRCP). The patient underwent appropriate treatment with antibiotics. Upon a three-week follow-up, the patient’s symptoms subsided, and her laboratory parameters normalized. Although Streptococcus anginosus is a normal gastrointestinal flora, it has the potential to form abscesses. Our report indicates the importance of considering Streptococcus anginosus in the differential diagnosis. Management includes four to six weeks of antibiotic therapy together with drainage of larger abscesses.

Multiple liver abscesses and bacteremia caused by Streptococcus constellatus infection: a case report

The Streptococcus milleri group (SMG) comprises commensal mucosal bacteria. Pyogenic liver abscesses due to hematogenous SMG infection are rare but can be observed even in healthy patients. In such cases, physicians should consider the existence of primary lesions that allow penetration of the SMG.

Bloodstream infections caused by Streptococcus anginosus group bacteria: A retrospective analysis of 78 cases at a Japanese tertiary hospital

OBJECTIVES

To investigate the characteristics of Streptococcus anginosus group (SAG) bacteremia in recent years, we conducted a retrospective cohort study and compared its findings with the data from previous studies.

METHODS

All patients with positive blood cultures from May 2005 to September 2014 in a tertiary care center with 925 beds were included.

RESULTS

There were 78 cases of SAG bacteremia (51 cases men; median age, 68 years) during the study period. The most common comorbidities were solid tumors in 32.1% of the patients. The most common infection source was hepatobiliary in one-third of all cases. Other infection sites included the following: intra-abdominal (12.8%), thoracic (10.3%), musculoskeletal (9%), urinary tract (7.7%), soft tissues (7.7%), and cervicofacial (6.4%). Susceptibility to penicillin, clindamycin and erythromycin were 100% (78/78), 95% (70/74) and 85% (39/46), respectively. Surgery along with systemic antibiotic treatment was administered in 53% of the cases. In-hospital mortality was 14.1%.

CONCLUSION

The clinical sources of the SAG bacteria were diverse, and hepatobiliary infection was the most common source of infection. In more than half of the patients, surgical treatment was performed. Susceptibility to penicillin was 100%, but susceptibility to erythromycin was lower than that reported in previous studies.

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

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 ≤ 18 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, χ2 test, Student's t-test or Fisher's exact test as appropriate and a two-tailed P value of ≤ 0.05 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 β-lactam/β-lactamase 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.