Milleri group streptococcus—a stepchild in the viridans family

Diversity of CRISPR-Cas type II-A systems in Streptococcus anginosus

Streptococcus anginosus is a commensal Streptococcal species that is often associated with invasive bacterial infections. However, little is known about its molecular genetic background. Many Streptococcal species, including S. anginosus, harbor clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems. A CRISPR-Cas type II-A system as well as a type II-C system have been reported for this species. To characterize the CRISPR-Cas type II systems of S. anginosus in more detail, we conducted a phylogenetic analysis of Cas9 sequences from CRISPR-Cas type II systems with a special focus on streptococci and S. anginosus. In addition, a phylogenetic analysis of S. anginosus strains based on housekeeping genes included in MLST analysis, was performed. All analyzed Cas9 sequences of S. anginosus clustered with the Cas9 sequences of CRISPR type II-A systems, including the Cas9 sequences of S. anginosus strains reported to harbor a type II-C system. The Cas9 genes of the CRISPR-Cas type II-C systems of other bacterial species separated into a different cluster. Moreover, analyzing the CRISPR loci found in S. anginosus, two distinct csn2 genes could be detected, a short form showing high similarity to the canonical form of the csn2 gene present in S. pyogenes. The second CRISPR type II locus of S. anginosus contained a longer variant of csn2 with close similarities to a csn2 gene that has previously been described in Streptococcus thermophilus. Since CRISPR-Cas type II-C systems do not contain a csn2 gene, the S. anginosus strains reported to have a CRISPR-Cas type II-C system appear to carry a variation of CRISPR-Cas type II-A harboring a long variant of csn2.

A Rare Case of Primary Purulent Pericarditis Caused by Streptococcus constellatus

Background: Bacteria-caused acute pericarditis is a very rare entity. It is usually associated with an underlying infection or compromised immune system. Primary purulent pericarditis in a previously healthy individual is highly unexpected; therefore, it is likely to have a delayed diagnosis and poor outcomes. Case: We report a case of an adult immunocompetent patient with primary bacterial pericarditis caused by a member of the commensal oral flora Streptococcus constellatus. The patient presented with septic shock and cardiac tamponade, and was further complicated with constrictive pericarditis, which was successfully treated with pericardiectomy. Conclusions: Bacterial pericarditis is a fulminant disease with a high mortality and complication rate. Fast recognition and prompt therapy are required to achieve a full recovery.

The Clinical Features and Management of Empyema Caused by Streptococcus constellatus

Background

Streptococcus constellatus, a commensal, plays an important role in purulent infections. It has been reported as aggressive pathogen causing pleural empyema. But the role of S. constellatus in empyema has not been taken seriously. There are no studies about clinical characteristics of empyema caused by S. constellatus domestically and abroad. This study aimed to explore the clinical features and management of empyema caused by S. constellatus.

Methods

A retrospective review of 9 patients diagnosed with empyema caused by S. constellatus in a hospital between January 2010 and August 2021 was performed.

Results

S. constellatus empyema were mostly seen in old males (66.7%) with comorbid diseases. The high-risk factors include diabetes mellitus, oral infection, and oral surgery. All were unilateral encapsulated empyema (right-side, 55.6%), diagnosed with pneumonia (bilateral pneumonia, 88.9%; ipsilateral lung abscess, 44.4%). 33.3% of patients had S. constellatus and anaerobes co-isolated. S. constellatus were sensitive to penicillin G, linezolid, levofloxacin, vancomycin, ceftriaxone, and chloramphenicol, resistant to erythromycin, tetracycline, and clindamycin. 33.3% of the patients needed ventilator support. The primary treatment to S. constellatus empyema was timely pus drainage, intravenous antibiotics, and enough nutrition support, intrapleural fibrinolytics and surgery (VAST recommended first) in necessity.

Conclusion

S. constellatus may cause pneumonia and lung abscess first and then spread to cause empyema mainly in old males with comorbid diseases. S. constellatus often co-isolated with anaerobes in empyema. Antibiotics should cover simultaneously both S. constellatus and anaerobes.

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.

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

Three distinct streptococcal species: Streptococcus anginosus, Streptococcus intermedius, and Streptococcus constellatus, belonging to the Streptococcus anginosus group (SAG), also known as Streptococcus milleri group, have been attracting clinicians and microbiologists, not only as oral commensals but also as opportunistic pathogens. For years they have been simply classified as so called viridans streptococci, and distinct species were not associated with particular clinical manifestations. Therefore, description of SAG members are clearly underrepresented in the literature, compared to other medically relevant streptococci. However, the increasing number of reports of life-threatening infections caused by SAG indicates their emerging pathogenicity. The improved clinical data generated with the application of modern molecular diagnostic techniques allow for precise identification of individual species belonging to SAG. This review summarizes clinical reports on SAG infections and systematizes data on the occurrence of individual species at the site of infection. We also discuss the issue of proper microbiological diagnostics, which is crucial for further clinical treatment.

The Role of SilX in Bacteriocin Production of Streptococcus anginosus

Streptococcus anginosus produces the novel antimicrobial peptide Angicin, which inhibits Gram positive microorganisms and is classified as a group IId bacteriocin. Production of Angicin is regulated by the quorum sensing system Sil (Streptococcus invasion locus), which is located adjacent to the bacteriocin gene cluster. Within this genetic region a typical CAAX protease is encoded, which was designated SilX. Nelfinavir, a HIV protease inhibitor, led to a concentration dependent reduction in antimicrobial activity, presumably through the inhibition of SilX. Concentrations exceeding 25 μM Nelfinavir caused a complete abolishment of bacteriocin activity against Listeria monocytogenes. These results are supported by the observation, that a SilX deletion mutant of S. anginosus strain BSU 1211 no longer inhibits the growth of L. monocytogenes. Antimicrobial activity could be restored by addition of synthetically synthesized mature SilCR, implying that SilX may be involved in the export and processing of the signal peptide SilCR. Some CAAX proteases have been reported to provide immunity against bacteriocins. However, in a radial diffusion assay the deletion mutant S. anginosus BSU 1211ΔSilX showed no sensitivity toward Angicin arguing against a role of SilX in the immunity of S. anginosus. The putative processing of the signal peptide SilCR indicates a novel function of the CAAX protease SilX, in the context of S. anginosus bacteriocin production.

Central Nervous System Infections Due to Streptococcus anginosus Group: A Single-Center Case Series

BACKGROUND

The Streptococcus anginosus group is known for its pathogenicity and tendency for abscess formation. The S anginosus group also causes brain abscesses, yet few studies describe this presentation in the pediatric neurology literature. We describe 5 patients with central nervous system infection due to S anginosus group evaluated by child neurologists at the University of Iowa from 2014 to 2020.

METHODS

We performed a retrospective case series review of electronic medical records detailing the clinical presentation and course of pediatric patients with S anginosus group-associated central nervous system infection.

RESULTS

We identified 4 males and 1 female (8, 11, 14, 16, and 21 years). Brain imaging showed abscesses in 4 cases and empyema in 1. All underwent neurosurgical intervention and antibiotic treatment. Cultures obtained during the neurosurgical procedure grew S anginosus group (4 cases with Streptococcus intermedius and 1 with Streptococcus constellatus). An 8-year-old boy with a delayed diagnosis died from brain herniation.

CONCLUSIONS

Central nervous system infections due to the S anginosus group can be life-threatening. Neuroimaging plays a key role in the early identification of abscesses. Prompt surgical intervention and timely initiation of antibiotics are critical for optimal outcomes.

Distribution, Diversity and Roles of CRISPR-Cas Systems in Human and Animal Pathogenic Streptococci

Streptococci form a wide group of bacteria and are involved in both human and animal pathologies. Among pathogenic isolates, differences have been highlighted especially concerning their adaptation and virulence profiles. CRISPR-Cas systems have been identified in bacteria and many streptococci harbor one or more systems, particularly subtypes I-C, II-A, and III-A. Since the demonstration that CRISPR-Cas act as an adaptive immune system in Streptococcus thermophilus, a lactic bacteria, the diversity and role of CRISPR-Cas were extended to many germs and functions were enlarged. Among those, the genome editing tool based on the properties of Cas endonucleases is used worldwide, and the recent attribution of the Nobel Prize illustrates the importance of this tool in the scientific world. Another application is CRISPR loci analysis, which allows to easily characterize isolates in order to understand the interactions of bacteria with their environment and visualize species evolution. In this review, we focused on the distribution, diversity and roles of CRISPR-Cas systems in the main pathogenic streptococci.

The changing microbiology of neck abscesses in children: implications for antibiotic therapy

Objectives

To provide an update on the microbiology, sensitivity rates and antibiotic prescribing patterns for superficial neck lymph node abscesses at Scotland's largest paediatric tertiary centre. Findings were compared to historical data from our institution.

Methods

A retrospective case series was conducted of paediatric patients undergoing incision and drainage of a superficial neck lymph node abscess at the Royal Hospital for Children in Glasgow, from 2018 to 2021.

Results

Thirty-nine abscesses were identified. Methicillin-susceptible Staphylococcus aureus was the commonest micro-organism (28 per cent), followed by Streptococcus pyogenes (13 per cent). Eighty-two per cent of patients were administered a drug regimen containing co-amoxiclav. Only three children required a change in their antibiotics.

Conclusion

There was a significant change in causative micro-organisms, including a decrease in S aureus and an increase in the Streptococcus anginosus group. Empirical use of co-amoxiclav is recommended. In abscesses showing no clinical improvement, second-line options such as clindamycin, cefotaxime and vancomycin should be considered.

Angicin, a novel bacteriocin of Streptococcus anginosus

As a conserved defense mechanism, many bacteria produce antimicrobial peptides, called bacteriocins, which provide a colonization advantage in a multispecies environment. Here the first bacteriocin of Streptococcus anginosus, designated Angicin, is described. S. anginosus is commonly described as a commensal, however it also possesses a high pathogenic potential. Therefore, understanding factors contributing to its host colonization and persistence are important. A radial diffusion assay was used to identify S. anginosus BSU 1211 as a potent bacteriocin producer. By genetic mutagenesis the background of bacteriocin production and the bacteriocin gene itself were identified. Synthetic Angicin shows high activity against closely related streptococci, listeria and vancomycin resistant enterococci. It has a fast mechanism of action and causes a membrane disruption in target cells. Angicin, present in cell free supernatant, is insensitive to changes in temperature from - 70 to 90 °C and pH values from 2 to 10, suggesting that it represents an interesting compound for potential applications in food preservation or clinical settings.

Characterization of Esophageal Microbiota in Patients With Esophagitis and Esophageal Squamous Cell Carcinoma

Microbial imbalances have been well elucidated in esophageal adenocarcinoma. However, few studies address the microbiota in esophageal squamous cell carcinoma (ESCC) and esophagitis (ES). We aimed to explore the association of esophageal microbiota with these patients. Esophageal tissues were obtained from healthy controls and ES and ESCC patients undergoing upper endoscopy. 16S rRNA gene sequencing was applied to analyze the microbiome. The α and β diversity differences were tested by Tukey test and partial least squares-discriminant analysis (PLS-DA), respectively. Linear discriminant analysis effect size (LEfSe) analysis was performed to assess taxonomic differences between groups. A total of 68 individuals were enrolled (control = 21, ES = 15, ESCC = 32). Microbial diversity was significantly different between the ESCC patients and healthy controls by Chao1 index, Shannon index, and PLS-DA. Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria were the five dominant bacterial phyla among the three groups. Megamonas, Collinsella, Roseburia, and Ruminococcus_2 showed a significantly continuous decreasing trend from the control group to the ESCC group at the genus level. When compared with the control group, decreased Fusobacteria at phylum level and Faecalibacterium, Bacteroides, Curvibacter, and Blautia at genus level were detected. ESCC samples also displayed a striking reduction of Bacteroidetes, Faecalibacterium, Bacteroides, and Blautia in comparison with the ES patients. LEfSe analysis indicated a greater abundance of Streptococcus, Actinobacillus, Peptostreptococcus, Fusobacterium, and Prevotella in the ESCC group. Our study suggests a potential association between esophageal microbiome dysbiosis and ESCC and provides insights into potential screening markers for esophageal cancer.

Acute suppurative thyroiditis due to Streptococcus anginosus leading to sepsis and acute respiratory distress syndrome: a case report

Acute suppurative thyroiditis (AST) is a rare but potentially life-threatening thyroid disease with a high mortality if left untreated. Thus, differentiation from other thyroid disorders is highly important in clinical practice. A 22-year-old male patient was admitted to a tertiary care hospital with cervical pain, palpitations, thyrotoxicosis, and an inhomogeneously enlarged right thyroid lobe. In view of the clinical findings, subacute thyroiditis (SAT) was suspected and treatment with glucocorticoids was started. After initial amelioration, the patient developed cervical erythema, fever, and recurrent pain. A CT scan showed extensive phlegmonous inflammation and abscess formation, suggestive of AST. We started immediate empiric antibiotic therapy and performed surgical drainage of the abscess formations. Subsequently, the patient developed hypoxic respiratory failure, leading to ICU admission and intermittent need for non-invasive ventilation. Blood and abscess cultures were positive for Streptococcus anginosus. If left untreated, AST represents a potentially life-threatening disease. Thus, in clinically doubtful cases, liberal further assessment by means of cervical CT scans or fine needle aspiration biopsy are strongly advised.

Presentation and outcomes of orbital cellulitis caused by Group F Streptococcus

PURPOSE:

To compare the presentation and outcomes of patients with orbital cellulitis requiring surgical intervention caused by the Group F Streptococcus (GFS) versus other bacteria. We hypothesize that patients with GFS infections have a more severe presentation and worse clinical outcomes compared to infections by other bacteria.

METHODS:

After Institutional Review Board approval at a large academic institutional center, 70 patients with culture-positive orbital cellulitis who required surgical intervention were identified. Clinical examinations before and after surgery as well as preoperative imaging with computed tomography and/or magnetic resonance imaging were reviewed. The study measures were preoperative and postoperative vision, motility, involved sinus disease, complications, and total hospital length of stay. Multiple imputation was used for missing data. Characteristics of patients were compared using Chi-square and Wilcoxon rank-sum.

RESULTS:

Nineteen patients (27%) had positive cultures for GFS and 51 patients (73%) had positive cultures for other bacterial species. There was no significant difference in visual acuity, motility, or inflammatory markers in patients with GFS compared to other patients. Patients with GFS were noted to have more sinus involvement on presentation compared to patients with other bacterial infections (P = 0.007).

CONCLUSION:

GFS associated orbital cellulitis is associated with significantly more sinus involvement, but has similar outcomes as orbital cellulitis from other bacterial species.

Conjunctival Commensal Isolation and Identification in Mice

The ocular surface was once considered immune privileged and abiotic, but recently it appears that there is a small, but persistent commensal presence. Identification and monitoring of bacterial species at the ocular mucosa have been challenging due to their low abundance and limited availability of appropriate methodology for commensal growth and identification. There are two standard approaches: culture based or DNA sequencing methods. The first method is problematic due to the limited recoverable bacteria and the second approach identifies both live and dead bacteria leading to an aberrant representation of the ocular space. We developed a robust and sensitive method for bacterial isolation by building upon standard microbiological culturing techniques. This is a swab-based technique, utilizing an "in-lab" made thin swab that targets the lower conjunctiva, followed by an amplification step for aerobic and facultative anaerobic genera. This protocol has allowed us to isolate and identify conjunctival species such as Corynebacterium spp., Coagulase Negative Staphylococcus spp., Streptococcus spp., etc. The approach is suitable to define commensal diversity in mice under different disease conditions.

Atypical Streptococcal Meningitis with Fatal Cerebrovascular Complications: A Case Report

Bacterial meningitis is an infectious pathology that remains a public health challenge. The most frequent etiological agent is Streptococcus pneumoniae, which is also associated with higher rates of mortality and sequels. However, less is known about the clinical presentation of atypical non-pneumoniae streptococcal meningitis. Here, we studied a 23-year-old man with no medical background who presented with projectile vomiting, states of consciousness alteration, unilateral cranial nerve palsy, and meningeal signs. Neuroimaging showed tonsillar herniation, regions of empyema, right transverse and sigmoid sinuses thrombosis, and multiple arterial subcortical infarcts. Cerebrospinal fluid suggested bacterial infection; blood and abscess cultures were positive for Streptococcus constellatus. The patient received antibiotics with no clinical improvement. He deteriorated over the following days, the abolishment of brainstem reflexes was observed, and brain death was declared. Streptococcal meningitis produced by atypical species is a potential cause of lethal cerebrovascular complications, even in immunocompetent patients.

Streptococcus anginosus group infections: Management and outcome at a tertiary care hospital

BACKGROUND

Data on patients with invasive Streptococcus anginosus group (SAG) infections is limited, as it's been considered commensal bacteria in the human microbiota. We conducted an analysis of SAG infections to assist clinicians in understanding their burden and clinical outcomes.

METHODS

A retrospective study of medical records, identifying invasive SAG bacteria of sterile-site isolates that were managed from May 2015 to April 2017, at a tertiary care hospital in Riyadh, Saudi Arabia. Demographic data, clinical presentation, site of infection, antibiotic use, and outcome were recorded and analyzed to identify factors associated with poor outcome and/or polymicrobial growth.

RESULTS

We identified 105 cases of SAG infections in adults, with 52% of the patients being male and the mean age of 52.4 years with comorbidities occurring in more than half of the cases such as diabetes (38%) and malignancy (15%). Overall mortality was 6%, and it was statistically associated with age older than 65 years, polymicrobial growth and a history of malignancy. The infection frequencies were skin and soft tissue infections (SSTI; 55%), intra-abdominal infections (24%), bacteremia (14%), genitourinary infections (8.5%), and pleuropulmonary infections (5%). Abscesses accounted for 68% of cases. Polymicrobial infection (46%) with Enterobacteriaceae and Gram-negative anaerobes coincided with SAG infection. Polymicrobial growth was significantly associated with abscess formation, intra-abdominal source of infections, and poor outcome. In addition, death in patients with SAG was statistically associated with patients older than 65 years of age and those with history of cancer or transplant.

CONCLUSION

SSTIs and intra-abdominal infections are the most common clinical presentations in our cohort. Bacteremia was uncommon; however, the prognosis is less favorable. Overall susceptibility to penicillin was 91%, therefore β-lactam antibiotics are the drug of choice and additional coverage for anaerobic and gram-negative bacteria should be considered for intra-abdominal collection and solid or organ abscesses.

Draft Genome Sequence of Streptococcus anginosus UMB7768, Isolated from a Woman with Recurrent UTI Symptoms

Streptococcus anginosus recently was implicated as a pathogen involved in urinary tract infections. A strain of S. anginosus was isolated from the female urogenital tract. Here, we present the draft genome sequence of S. anginosus strain UMB7768.

Streptococcus anginosus recently was implicated as a pathogen involved in urinary tract infections. A strain of S. anginosus was isolated from the female urogenital tract. Here, we present the draft genome sequence of S. anginosus strain UMB7768.

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

Streptococcus intermedius is a β-hemolytic Gram-positive member of the Streptococcus anginosus group (SAG). Despite being a part of the normal microbiota, it is one of the most common pathogens associated with brain and liver abscesses and thoracic empyema, increasing as a result the morbidity and mortality rates in affected patients. Though there are numerous published case reports on S. intermedius infections, it is still understudied compared to other SAG members. Our knowledge of the genomic factors contributing to its dissemination to the brain and abscess development is also limited to few characterized genes. In this review, we summarize our current knowledge on S. intermedius identification methods, virulence factors, and insight provided by the whole-genome and correlate patients’ metadata, symptoms, and disease outcome with S. intermedius infections in 101 recent case reports obtained from PubMed. This combined information highlights the gaps in our understanding of S. intermedius pathogenesis, suggesting future research directions to unveil the factors contributing to abscess development.

COMPLICATED PNEUMONIA WITH EMPYEMA CAUSED BY STREPTOCOCCUS ANGINOSUS IN A CHILD

Objective:

To highlight the pathogenicity of Streptococcus anginosus, which is rare in pediatric patients, but can cause severe infections that are known to have a better outcome when treated early with interventional procedures and prolonged antibiotic therapy.

Case

description: The patient is a 6-year-old boy with global developmental delay, examined in the emergency room due to fever and respiratory distress. The physical examination and diagnostic workout revealed complicated pneumonia with empyema of the left hemithorax; he started antibiotic therapy and underwent thoracic drainage. Pleural fluid cultures grew Streptococcus anginosus. On day 11, the child had a clinical deterioration with recurrence of fever, hypoxia, and respiratory distress. At this point, considering the causative agent, he was submitted to video-assisted thoracoscopic decortication, with good progress thereafter.

Comments:

Streptococcus anginosus is a commensal bacterium of the human oral cavity capable of causing severe systemic infections. Although reports of complicated thoracic infections with this agent are rare in the pediatric population, they have been increasing in adults. Streptococcus anginosus has a high capacity to form abscess and empyema, requiring different therapeutic approaches when compared to complicated pneumonia caused by other agents.

Heterogeneity of Streptococcus anginosus ß-hemolysis in relation to CRISPR/Cas

Streptococcus anginosus is a commensal of the oral mucosa that can cause severe invasive infections. A considerable proportion of Streptococcus anginosus strains are ß-hemolytic due to the presence of an SLS-like gene cluster. However, the majority of strains do not display ß-hemolysis. To investigate ß-hemolysin heterogeneity in S. anginosus, we determined the presence of sag genes and correlated it with the presence of CRISPR/Cas genes in a collection of ß-hemolytic and non-ß-hemolytic strains. All of the ß-hemolytic strains carried the sag gene cluster. In contrast to other streptococci, clinical S. anginosus strains that do not display ß-hemolysis do not harbor sag genes. Phylogenetic analysis of the ß-hemolytic strains revealed that they belong to two previously defined clusters within S. anginosus. Correlation with CRISPR/Cas genes showed a significant difference for the presence of CRISPR/Cas in ß-hemolytic versus non-ß-hemolytic isolates. The presence of the CRISPR/Cas type IIA or type IIC locus is associated with the absence of sag genes; in 65% of the non-ß-hemolytic strains a CRISPR/Cas locus was found, while only 24% of ß-hemolytic strains carry CRISPR/Cas genes. Further analysis of the spacer content of the CRISPR systems revealed the presence of multiple self-targeting sequences directed against S. anginosus genes. These results support the hypothesis that horizontal gene transfer is involved in the acquisition of ß-hemolysin genes and that CRISPR/Cas may limit DNA uptake in S. anginosus.

Co-infection with Streptococcus anginosus and Mycobacterium tuberculosis in an immunocompetent pediatric patient. A case report

BACKGROUND

Simultaneous infection in tuberculosis (TB) is rare. The mixed infection between Streptococcus anginosus group (SAG) and M. tuberculosis (MTB) has not been reported in children. The aim of this report was to describe a pediatric case with a pulmonary abscess caused by the duality SAG-MTB co-infection.

CASE PRESENTATION

An 11-year-old boy with an acute onset of throbbing pain of two-day evolution located in the anterior chest wall. The patient reported a history of fever, cough and rhinorrhea during the last seven days. An anterior chest radiography revealed a heterogenic opacity at the lower right lobe while the lateral projection showed an obliteration at the anterior diaphragmatic insertion. Parenteral Ceftriaxone (100 mg/kg/day) and Dicloxacillin (200 mg/kg/day) was started. The abscess was subsequently drained and analyzed. After a year of follow-up, the patient remained asymptomatic.

CONCLUSION

This case represents the first reported case of pulmonary co-infection involving MTB and SAG in an immunocompetent pediatric patient.

The Pathogenesis Of Streptococcus anginosus In Aerobic Vaginitis

Background

Aerobic vaginitis (AV) is a newly defined type of bacterial vaginitis, but its pathogenesis is not yet clear. Streptococcus anginosus appears as an emerging pathogen in recent case reports, and colonizes in vagina of patients with AV. In this study, we investigate the pathogenesis of S. anginosus in AV.

Materials and methods

(1) We collected 41 vaginal specimens from 21 healthy, fertile women with normal vaginal flora (NM), 10 with bacterial vaginosis (BV) and 10 with AV; their microbiome structure was analysed by 16S rRNA gene sequencing. (2) S. anginosus and vaginal epithelial cells were cocultured in vitro, and cytotoxicity was tested by an LDH kit. (3) The S. anginosus virulence gene sag was knocked out, and the cytotoxicity of the mutant in vaginal epithelial cells was tested.

Results

(1) The microbiome structure of AV was dramatically different from that of BV and NM. The predominant genera of the three groups were Streptococcus spp., Gardnerella spp. and Lactobacillus spp. Streptococcus spp. were significantly more abundant in AV than in BV (95% CI [0.1391, 0.8676], P<0.01) and NM (95% CI [0.1391, 0.8676], P<0.01). (2) S. anginosus was the dominant species in AV (95% CI [0.04672, 0.1097], P<0.01). (3) The mean cytotoxicity of S. anginosus in vaginal epithelial cells was 58.34% for the wild type (WT) and 16.43% for the mutant; this difference was significant (95% CI [−60.55, −23.28], P<0.01).

Conclusion

S. anginosus was the predominant microorganism in patients with AV in our study. S. anginosus caused vaginal epithelial cell lysis, indicating that S. anginosus is an AV pathogen. The S. anginosus virulence gene sag is vital for vaginal epithelial cell lysis.

Traditional culture methods fail to detect principle pathogens in necrotising soft tissue infection: a case report

OBJECTIVE

Necrotising soft tissue infections (NSTIs) progress rapidly and mortality remains high, ranging from 10% to 30%, representing a significant challenge for health professionals. Early accurate diagnosis is crucial because timely and aggressive surgical intervention remains the number one indicator for a better clinical outcome. Understanding the microbial background of NSTIs would aid early diagnosis.

PRESENTATION

We present a case of NSTI, in a seemingly healthy adult male, originating from a tooth abscess. The NSTI progressed rapidly, and eventually covered the patient's chest and abdominal skin and underlying soft tissue.

RESULTS

Traditional blood and tissue culture only found Group C Streptococcus where 16S sequencing detected abundant Prevotella spp., a more likely causal organisms of the NSTI. The use of antibiotics with the approriate anaerobe coverage, in combination with timely surgical intervention, contributed to the ultimate successful clinical outcome. Complete wound healing and successful graft was achieved within one month of diagnosis of the microbes present.

CONCLUSION

While surgical intervention remains the most important consideration in treatment of NSTI, correct identifcation of the microbial flora could also contribute to successful treatment.

Comparative Analysis of Gut Microbiota Among the Male, Female and Pregnant Giant Pandas (Ailuropoda Melanoleuca)

The giant panda (GP) was the most endangered species in China, and gut microbiota plays a vital role in host health. To determine the differences of the gut microbiota among the male, female and pregnant GPs, a comparative analysis of gut microbiota in GPs was carried out by 16S rRNA and ITS high-throughput sequencing. In 16S rRNA sequencing, 435 OTUs, 17 phyla and 182 genera were totally detected. Firmicutes (53.6%) was the predominant phylum followed by Proteobacteria (37.8%) and Fusobacteria (7.1%). Escherichia/Shigella (35.9%) was the most prevalent genus followed by Streptococcus (25.9%) and Clostridium (11.1%). In ITS sequencing, 920 OTUs, 6 phyla and 322 genera were also detected. Ascomycota (71.3%) was the predominant phylum followed by Basidiomycota (28.4%) and Zygomycota (0.15%). Purpureocillium (4.4%) was the most prevalent genus followed by Cladosporium (2.5%) and Pezicula (2.4%). Comparative analysis indicated that the male GPs harbor a higher abundance of phylum Firmicutes than female GPs with the contribution from genus Streptococcus. Meanwhile, the female GPs harbor a higher abundance of phylum Proteobacteria than male GPs with the contribution from genus Escherichia/ Shigella. In addition, the shift in bacteria from female to pregnant GPs indicated that phylum Firmicutes increased significantly with the contribution from Clostridium in the gut, which may provide an opportunity to study possible associations with low reproduction of the GPs.

A Rare Case of Myonecrosis with Soft-Tissue Emphysema in a Diabetic Foot Caused by Streptococcus anginosus Isolated in Pure Culture: A Case Study

Streptococcus anginosus (SAG) is a known human pathogen and member of the Streptococcus milleri group. SAG is a known bacterial cause of soft-tissue abscesses and bacteremia and is an increasingly prevalent pathogen in infections in patients with cystic fibrosis. We describe a rare case of SAG as an infectious agent in a case of nonclostridial myonecrosis with soft-tissue emphysema. This is the only case found in the literature of SAG cultured as a pure isolate in this type of infection and was associated with a prolonged course of treatment in an otherwise healthy patient.

Microbiology and clinical characteristics of viridans group streptococci in patients with cancer

This study assessed the microbiology, clinical syndromes, and outcomes of oncologic patients with viridans group streptococci isolated from blood cultures between January 1st, 2013 and December 31st, 2016 in a referral hospital in Mexico using the Bruker MALDI Biotyper. Antimicrobial sensitivity was determined using BD Phoenix 100 according to CLSI M100 standards. Clinical information was obtained from medical records and descriptive analysis was performed.

Forty-three patients were included, 22 females and 21 males, aged 42 ± 17 years. Twenty (46.5%) patients had hematological cancer and 23 (53.5%) a solid malignancy. The viridans group streptococci isolated were Streptococcus mitis, 20 (46.5%); Streptococcus anginosus, 14 (32.6%); Streptococcus sanguinis, 7 (16.3%); and Streptococcus salivarius, 2 (4.7%). The main risk factors were pyrimidine antagonist chemotherapy in 22 (51.2%) and neutropenia in 19 (44.2%) cases, respectively. Central line associated bloodstream infection was diagnosed in 18 (41.9%) cases. Septic shock occurred in 20.9% of patients, with an overall mortality of 18.6%. Only four S. mitis revealed penicillin-resistance.

Our results are similar to those of other series, identifying these bacteria as emerging pathogens with significant morbidity and mortality in oncologic patients. The MALDI-TOF system increased the rate of viridans group streptococci isolation in this population.

Regulation of the β-hemolysin gene cluster of Streptococcus anginosus by CcpA

Streptococcus anginosus is increasingly recognized as an opportunistic pathogen. However, our knowledge about virulence determinants in this species is scarce. One exception is the streptolysin-S (SLS) homologue responsible for the β-hemolytic phenotype of the S. anginosus type strain. In S. anginosus the expression of the hemolysin is reduced in the presence of high glucose concentrations. To investigate the genetic mechanism of the hemolysin repression we created an isogenic ccpA deletion strain. In contrast to the wild type strain, this mutant exhibits hemolytic activity in presence of up to 25 mM glucose supplementation, a phenotype that could be reverted by ccpA complementation. To further demonstrate that CcpA directly regulates the hemolysin expression, we performed an in silico analysis of the promoter of the SLS gene cluster and we verified the binding of CcpA to the promoter by electrophoretic mobility shift assays. This allowed us to define the CcpA binding site in the SLS promoter region of S. anginosus. In conclusion, we report for the first time the characterization of a potential virulence regulator in S. anginosus.

Streptococcus anginosus endocarditis and multiple liver abscesses in a splenectomised patient

An unusual case of infective endocarditis and concurrent multiple liver abscesses both caused by Streptococcus anginosus in a splenectomised patient is reported. The microorganism is a very rare cause of endocarditis and its presentation with multiple liver abscesses is highly unusual. It was initially misdiagnosed as Streptococcus sanguinis and issues relating to the different clinical presentations of S. anginosus including the rare cases of endocarditis, the role of the patient's splenectomy and problems that may contribute to its potential laboratory misidentifications are discussed.

A rare case of pyogenic pericarditis secondary to Streptococcus constellatus

We report an extremely rare case of purulent pericarditis caused by the normally commensal oral flora, Streptococcus constellatus, a viridans Streptococcal species and member of the S. anginosus group (previously also known by the eponymous 'S. milleri', for American Willoughby Dayton Miller). This case is a previously healthy 71-year-old immunocompetent woman from Arizona who presented with a 5-day history of progressive shortness of breath and chest tightness, and subjective fever and chills, but without history of nausea, vomiting, night sweats, recent travel, autoimmune disease or sick contacts. Early recognition and intervention of purulent pericarditis allow patients like the one outlined in this case to achieve full recovery.

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

Streptococcus anginosus is considered a human commensal but improvements in species identification in recent years have highlighted its role as an emerging pathogen. However, our knowledge about the pathogenicity mechanisms in this species is scarce. One reason for this is the lack of published genetic manipulation techniques in the S. anginosus group. To establish a novel mutation technique we investigated the competence system of S. anginosus and created a Cre-recombinase-based mutation method that allows the generation of markerless gene deletions in S. anginosus. In silico analysis of the competence system demonstrated that S. anginosus encodes homologues for the vast majority of genes that are known to be essential for the transformation of S. pneumoniae. Analysis of transformation kinetics confirmed that S. anginosus SK52 possesses an S. pneumoniae-like competence development with a rapid increase of competence after treatment with Competence Stimulating Peptide (CSP), reaching a maximum transformation efficiency of 0.24% ± 0.08%. The combination of CSP-induced transformation and the Cre-lox system allows the efficient and fast creation of markerless gene deletions and will facilitate the investigation of the pathogenicity of S. anginosus on a genetic level.

Cerebellar abscesses, infective endocarditis and bacteraemia due to a rare pathogen: Streptococcus constellatus

Intracranial infections may result from contiguity, such as mastoiditis or acute otitis media, or from haematogenous dissemination from an infectious source. Streptococcus constellatus, a coccus from the normal genital, oral and gastrointestinal flora, has a tendency to form abscesses, but not to cause infective endocarditis (IE). Also, S. constellatus is an extremely rare causative agent of brain abscess. We report the case of a woman with a colorectal tumour who presented with IE and cerebellar abscesses due to a S. constellatus bacteraemia.

How to become a killer, or is it all accidental? Virulence strategies in oral streptococci

Streptococci are a diverse group of Gram-positive microorganisms sharing common virulence traits and similar strategies to escape the oral niche and establish an infection in other parts of the host organism. Invasive infection with oral streptococci is "a perfect storm" that requires the concerted action of multiple biotic and abiotic factors. Our understanding of streptococcal pathogenicity and infectivity should probably be less mechanistic and driven not only by the identification of novel virulence factors. The observed diversity of the genus, including the range of virulence and pathogenicity mechanisms, is most likely the result of interspecies interactions, a massive horizontal gene transfer between streptococci within a shared oral niche, recombination events, selection of specialized clones, and modification of regulatory circuits. Selective pressure by the host and bacterial communities is a driving force for the selection of virulence traits and shaping the streptococcal genome. Global regulatory events driving niche adaptation and interactions with bacterial communities and the host steer research interests towards attempts to define the oral interactome on the transcriptional level and define signal cross-feeding and co-expression and co-regulation of virulence genes.

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

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.

Streptococcus anginosus Group Bacterial Infections

BACKGROUND

The Streptococcus anginosus group (SAG) causes a variety of infections in adults. To better understand the burden of SAG infections and their associated morbidity and mortality, we conducted a retrospective analysis of these infections in adults at a tertiary care center.

METHODS

A retrospective review of all cultures positive for SAG in adults and a corresponding review of the patients' medical records were conducted at a tertiary care facility in central New York. Patients with these cultures during the period of January 2007-December 2011 were included. Demographic data, area of residence, clinical features and underlying illnesses, site of infection, length of hospital stay, antibiotic susceptibility and antibiotic therapy were recorded and analyzed.

RESULTS

There were 332 SAG cases; most patients were males (59%), mean age of 47 years and 84% lived in urban areas. Overall mortality was 3% with underlying conditions common such as diabetes (25%), hypertension (31%) and immunodeficiency (22%). Most of the infections were related to skin and soft tissue (72%) and polymicrobial (70%) with gram-negative anaerobes and Enterobacteriaceae commonly isolated with SAG.

CONCLUSIONS

We present the largest study, thus far, reviewing the clinical presentation, management and outcome of infections due to the SAG of organisms. Notable findings from our study are the low mortality associated with SAG infection, and the propensity to present as a skin and tissue and polymicrobial infection. Our findings will assist clinicians in managing patients with SAG infections and recognizing that S anginosus may be one of several organisms responsible for infection.

Pyogenic Pericarditis and Cardiac Tamponade Due to Streptococcus anginosus in a Combat Theater

Streptococcus anginosus group pericarditis is rare. A 24-year-old male soldier presented for care at a military clinic in Afghanistan with shock and cardiac tamponade requiring emergent pericardial drainage and aeromedical evacuation. We review the patient's case, the need for serial pericardial drainage, and the available literature on this disorder.

The sil Locus in Streptococcus Anginosus Group: Interspecies Competition and a Hotspot of Genetic Diversity

The Streptococcus Invasion Locus (Sil) was first described in Streptococcus pyogenes and Streptococcus pneumoniae, where it has been implicated in virulence. The two-component peptide signaling system consists of the SilA response regulator and SilB histidine kinase along with the SilCR signaling peptide and SilD/E export/processing proteins. The presence of an associated bacteriocin region suggests this system may play a role in competitive interactions with other microbes. Comparative analysis of 42 Streptococcus Anginosus/Milleri Group (SAG) genomes reveals this to be a hot spot for genomic variability. A cluster of bacteriocin/immunity genes is found adjacent to the sil system in most SAG isolates (typically 6–10 per strain). In addition, there were two distinct SilCR peptides identified in this group, denoted here as SilCR_SAG-A and SilCR_SAG-B, with corresponding alleles in silB. Our analysis of the 42 sil loci showed that SilCR_SAG-A is only found in Streptococcus intermedius while all three species can carry SilCR_SAG-B. In S. intermedius B196, a putative SilA operator is located upstream of bacteriocin gene clusters, implicating the sil system in regulation of microbe–microbe interactions at mucosal surfaces where the group resides. We demonstrate that S. intermedius B196 responds to its cognate SilCR_SAG-A, and, less effectively, to SilCR_SAG-B released by other Anginosus group members, to produce putative bacteriocins and inhibit the growth of a sensitive strain of S. constellatus.

Comparative Genome Analysis of the Daptomycin-Resistant Streptococcus anginosus Strain J4206 Associated with Breakthrough Bacteremia

Streptococcus anginosus is a member of the normal oral flora that can become a pathogen causing pyogenic infections in humans. The genome of daptomycin-resistant strain J4206, originally isolated from a patient suffering from breakthrough bacteremia and septic shock at the University of Texas Health Science Center at San Antonio, was determined. The circular genome is 2,001,352 bp long with a GC content of 38.62% and contains multiple mobile genetic elements, including the phage-like chromosomal island SanCI that mediates a mutator phenotype, transposons, and integrative conjugative elements. Daptomycin resistance involves multiple alterations in the cell membrane and cell wall, and unique features were identified in J4206 that may contribute to resistance. A cluster of capsular polysaccharide (CPS) genes for choline metabolism and transport are present that may help neutralize cell surface charges, destabilizing daptomycin binding. Further, unique J4206 genes encoding sortases and LPXTG-target proteins that are involved in cell wall modification were present. The J4206 genome is phylogenetically closely related to the recently reported vancomycin-resistant SA1 strain; however, these genomes differ with SNPs in cardiolipin synthetase, histidine kinase yycG, teichoic acid modification genes, and other genes involved in cell surface modification. Transmission electron microscopy showed that the cell walls of both strains J4206 and SA1 were significantly thicker and more electron dense than daptomycin- and vancomycin-sensitive strain J4211. This comparative genomic study has identified unique genes as well as allelic variants in the J4206 genome that are involved in cell surface modification and thus might contribute to the acquisition of daptomycin resistance.

Draft Genome Sequence of Streptococcus anginosus BVI, a New Vaginal Pathogen Candidate

Streptococcus anginosus is a pathogen implicated in urogenital and gastroinstestinal tract infections. Here, we report the draft genome sequence of S. anginosus BVI, isolated from a bacterial vaginosis patient attending a prenatal care unit in Cali, Colombia. The genome sequence of BVI consists of 2,014,025 bp, encoding 2,008 predicted proteins.

Epidemiologic and Microbiologic Characteristics of Occult Bacteremia Among Febrile Children in Southern Israel, Before and After Initiation of the Routine Antipneumococcal Immunization (2005-2012)

BACKGROUND

Little is known about the incidence and dynamics of occult bacteremia (OB) among infants/young children following the introduction of pneumococcal conjugate vaccines (PCVs) into the national immunization program in Israel in 2009-2010. The aim of this study was to characterize the epidemiologic and microbiologic picture of OB among febrile infants/children aged 3-36 months in southern Israel, before and after PCVs introduction.

METHODS

Retrospective study enrolling all infants/young children attending the emergency room of a tertiary medical center in southern Israel with fever without source, discharged, and reported with a positive blood culture.

RESULTS

Of 453 true bacteremias, 89 (19.6%) were defined as OB. OB rate was 0.22%; a significant decrease was recorded in OB rates, with the highest rate during 2005 (0.34%) and the lowest during 2011 (0.15%). OB cases decreased in post-PCV (2010-2012) versus prevaccination period (2005-2009) from 66/22,256 cases (0.3%) to 23/13,213 cases (0.17%; p = 0.03). Most frequent single OB pathogens were Streptococcus pneumoniae, Streptococcus viridans spp., and Kingella kingae (39.3%, 10.1%, and 9.0%, respectively); Enterobacteriaceae spp. were isolated in 10 cases (11.2%). No changes were recorded in S. pneumoniae-OB cases; K. kingae-OB decreased significantly (p = 0.047). None of the S. pneumoniae serotypes isolated during 2011-2012 belonged to 13-valent PCV (PCV13). An increase in non PCV13 serotypes was recorded during 2011-2012 (3/3, 100% vs. 7/32, 21.9%, p = 0.01).

CONCLUSION

OB rates decreased significantly following the introduction of PCVs. S. pneumoniae was the most frequent isolated pathogen in OB, but in lower percentages compared with the medical literature. No PCV13 serotypes were detected as a cause of OB during 2011-2012.

Case-control study of pneumonia patients with Streptococcus anginosus group bacteria in their sputum

BACKGROUND AND OBJECTIVE

In recent years, Streptococcus anginosus group (SAG) bacteria are becoming increasingly recognized as important pneumonia-causing pathogens. Although several small studies have been reported, the features of SAG pneumonia remain unclear, because the identification of SAG from sputum cultures is not routinely performed in most microbiology laboratories. The aim of this study was to elucidate the clinical characteristics of SAG pneumonia.

PATIENT AND METHODS

This was a retrospective case-control study utilizing data obtained in our hospital between September 2009 and June 2016. We investigated 31 patients with SAG pneumonia (PWP), and also assessed the difference between the 31 PWP and 37 patients without pneumonia (PWOP) in whose sputum SAG was detected.

RESULTS

Seventy-one percent of the patients were men and the median age was 78 years in the PWP. Univariate analysis indicated that the PWP were significantly more often a bed-ridden (p < 0.01) with comorbid aspiration than were the PWOP (p < 0.05). Among the PWP, nursing and healthcare-associated pneumonia (NHCAP) was the more common type of pneumonia (54.8%). S. anginosus was detected significantly more frequently in sputum cultures of PWP than PWOP (p < 0.01), and multiple pathogens were detected more frequently in PWP (p < 0.01). Streptococcus constellatus was the most frequently detected pathogen in patients with a single bacterial infection. Empyema was observed only in patients with multiple bacteria.

CONCLUSIONS

SAG should be recognized as important causative pathogens of pneumonia, particularly among elderly patients with underlying disease associated with aspiration. NHCAP was the more common type of SAG pneumonia in this study.

Streptococcus anginosus (milleri) Group Strains Isolated in Poland (1996-2012) and their Antibiotic Resistance Patterns

Streptococcus anginosus, Streptococcus intermedius and Streptococcus constellatus form a group of related streptococcal species, namely the Streptococcus Anginosus Group (SAG). The group, previously called "milleri" had been rarely described until 1980/1990 as source of infections. Nowadays SAG bacteria are often described as pathogens causing predominantly purulent infections. The number of infections is highly underestimated, as SAG strains are often classified in the microbiology laboratory as less virulent "viridans streptococci" Epidemiological situation regarding SAG infections in Poland has been unrecognized, therefore we performed a retrospective analysis of strains isolated between 1996 and 2012. Strains suspected of belonging to SAG were re-identified using an automated biochemical approach (Vitek2) and MALDI-TOF MS. We performed first analysis of antibiotic resistance among SAG strains isolated in Poland using automated methods (Vitek2), disk diffusion tests and E-Tests. We also performed PCR detection of resistance determinants in antibiotic resistant strains. Clonal structure of analyzed strains was evaluated with PFGE and MLVF methods. All three species are difficult to distinguish using automated diagnostic methods and the same is true for automated MIC evaluation. Our analysis revealed SAG strains are rarely isolated in Poland, predominantly from purulent infections. All isolates are very diverse on the genomic level as estimated by PFGE and MLVF analyses. All analyzed strains are sensitive to penicillin, a substantial group of strains is resistant to macrolides and the majority of strains are resistant to tetracycline.

Streptococcus milleri and Recurrent Intra-Abdominal Abscesses: A Case Report and Literature Review

We report a case of recurrent intra-abdominal abscesses as a postoperative complication following diverticular perforation in which Streptococcus milleri (SM) was isolated. SM is evaluated here as a potent pyogenic organism commonly associated with intra-abdominal abscess especially in the postoperative setting. With the commonly adopted conservative management, the challenges of recurrence and prolonged hospital stay experienced in the indexed case as well as many other previous reports are highlighted. We also present a recommendation of the need for a more intensive approach of SM-related abscess drainage along with areas that would benefit further research.

The clinical features of respiratory infections caused by the Streptococcus anginosus group

BACKGROUND

The Streptococcus anginosus group (SAG) play important roles in respiratory infections. It is ordinarily difficult to distinguish them from contaminations as the causative pathogens of respiratory infections because they are often cultured in respiratory specimens. Therefore, it is important to understand the clinical characteristics and laboratory findings of respiratory infections caused by the SAG members. The aim of this study is to clarify the role of the SAG bacteria in respiratory infections.

METHODS

A total of 30 patients who were diagnosed with respiratory infections which were caused by the SAG bacteria between January 2005 and February 2015 were retrospectively evaluated.

RESULTS

Respiratory infections caused by the SAG were mostly seen in male patients with comorbid diseases and were typically complicated with pleural effusion. Pleural effusion was observed in 22 (73.3%) patients. Empyema was observed in half of the 22 patients with pleural effusion. S. intermedius, S. constellatus and S. anginosus were detected in 16 (53.3 %), 11 (36.7 %) and 3 (10.0 %) patients, respectively. Six patients had mixed-infections. The duration from the onset of symptoms to the hospital visit was significantly longer in "lung abscess" patients than in "pneumonia" patients among the 24 patients with single infections, but not among the six patients with mixed-infection. The peripheral white blood cell counts of the "pneumonia" patients were higher than those of the "lung abscess" patients and S. intermedius was identified significantly more frequently in patients with pulmonary and pleural infections (pneumonia and lung abscess) than in patients with bacterial pleurisy only. In addition, the patients in whom S. intermedius was cultured were significantly older than those in whom S. constellatus was cultured.

CONCLUSIONS

Respiratory infections caused by the SAG bacteria tended to be observed more frequently in male patients with comorbid diseases and to more frequently involve purulent formation. In addition, S. intermedius was mainly identified in elderly patients with having pulmonary infection complicated with pleural effusion, and the aspiration of oral secretions may be a risk factor in the formation of empyema thoracis associated with pneumonia due to S. intermedius.

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.