"Streptococcus milleri" endocarditis caused by Streptococcus anginosus

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.

Whole genome and RNA sequencing of oral commensal bacterium Streptococcus anginosus subsp. anginosus with vancomycin tolerance

"Antibiotic tolerance" promotes the rapid subsequent evolution of "antibiotic resistance," however, it is often overlooked because it is difficult to distinguish between tolerant and susceptible organisms. A commensal bacterium S. anginosus subsp. anginosus strain KHUD_S1, isolated from dental biofilm was found to exhibit a high MBC/MIC ratio of 32 against vancomycin. We observed KHUD_S1 cells exposed to vancomycin did not grow but maintained viability. Transmission electron microscope showed KHUD_S1 cells possessed a dense, thick capsule and maintained the cell wall integrity upon vancomycin exposure. To infer the underlying mechanisms of the vancomycin tolerance in KHUD_S1, we performed whole genome sequencing and RNA sequencing. The KHUD_S1 genome carried three genes encoding branching enzymes that can affect peptidoglycan structure through interpeptide bridge formation. Global gene expression profiling revealed that the vancomycin-induced downregulation of carbohydrate and inorganic ion transport/metabolism as well as translation is less prominent in KHUD_S1 than in the vancomycin susceptible strain KHUD_S3. Based on the transcriptional levels of genes related to peptidoglycan synthesis, KHUD_S1 was determined to have a 3D peptidoglycan architecture distinct from KHUD_S3. It was found that, under vancomycin exposure, the peptidoglycan was remodeled through changes in the interpeptide bridge and transpeptidation reactions. Collectively, these features of S. anginosus KHUD_S1, including a dense capsule and differential gene expression in peptidoglycan synthesis, may contribute to vancomycin tolerance. Our results showing the occurrence of vancomycin tolerance amongst oral commensal bacteria highlight the need for considering future strategies for screening of antibiotic tolerance as an effort to reduce antibiotic resistance.

Septic shock caused by Slackia exigua in a patient with diabetes

We report a case of septic shock caused by Slackia exigua, an obligatory anaerobic gram-positive rod, in an 82-year-old woman with diabetes. Dental assessment revealed a palatal lesion and untreated periodontitis. Although a resident species in the oral cavity and associated with localized disorders, S. exigua can cause extra-oral diseases, which can be fatal in individuals with risk factors, such as diabetes. Thus, control of oral lesions caused by S. exigua is important to prevent systemic infection.

Clinical Features and Outcomes of Streptococcus anginosus Group Infective Endocarditis: A Multicenter Matched Cohort Study

Background

Although Streptococcus anginosus group (SAG) endocarditis is considered a severe disease associated with abscess formation and embolic events, there is limited evidence to support this assumption.

Methods

We performed a retrospective analysis of prospectively collected data from consecutive patients with definite SAG endocarditis in 28 centers in Spain and Italy. A comparison between cases due to SAG endocarditis and viridans group streptococci (VGS) or Streptococcus gallolyticus group (SGG) was performed in a 1:2 matched analysis.

Results

Of 5336 consecutive cases of definite endocarditis, 72 (1.4%) were due to SAG and matched with 144 cases due to VGS/SGG. SAG endocarditis was community acquired in 64 (88.9%) cases and affected aortic native valve in 29 (40.3%). When comparing SAG and VGS/SGG endocarditis, no significant differences were found in septic shock (8.3% vs 3.5%, P = .116); valve disorder, including perforation (22.2% vs 18.1%, P = .584), pseudoaneurysm (16.7% vs 8.3%, P = .108), or prosthesis dehiscence (1.4% vs 6.3%, P = .170); paravalvular complications, including abscess (25% vs 18.8%, P = .264) and intracardiac fistula (5.6% vs 3.5%, P = .485); heart failure (34.7% vs 38.9%, P = .655); or embolic events (41.7% vs 32.6%, P = .248). Indications for surgery (70.8% vs 70.8%; P = 1) and mortality (13.9% vs 16.7%; P = .741) were similar between groups.

Conclusions

SAG endocarditis is an infrequent but serious condition that presents a prognosis similar to that of VGS/SGG.

An Unusual Case of Streptococcus anginosus Endocarditis in a Healthy Host With Bicuspid Aortic Valve

Streptococcus anginosus group (SAG) is a subgroup of viridans streptococci and can be found ubiquitously in normal human flora. SAG is known to form invasive pyogenic infection when it becomes pathogenic. Yet, SAG is a very rare cause of endocarditis, and there is a dearth of case reports on this topic. We present a rare case of native bicuspid aortic valve endocarditis secondary to S. anginosus that caused aortic insufficiency and ascending aortic aneurysm. To our knowledge, this is the first well-documented case report of community-acquired S. anginosus endocarditis on a bicuspid aortic valve in an immunocompetent patient. The patient first presented with cough that was likely due to bronchus irritation from a 5.5 x 5.2 cm ascending aortic aneurysm. He underwent aortic valve replacement with bovine bioprosthesis and ascending aortic aneurysm repairment and was treated with a two-week regimen of IV ceftriaxone and gentamicin followed by another four weeks of IV ceftriaxone. He was eventually discharged to a rehabilitation facility. SAG is usually susceptible to beta-lactam antibiotics. The prognosis of SAG infection is usually good, but progression to bacteremia carries a poor outcome.

An Extremely Rare Case of Streptococcus anginosus Bacteremia Associated With Colon Cancer and Infective Endocarditis

Streptococcus anginosus (S. anginosus) is a subgroup of viridans streptococci that tend to form a deep-seated abscess. These bacteria can be part of healthy human flora and commonly found in the gastrointestinal tract and oral cavity. Infective endocarditis is most commonly caused by Staphylococcus aureus and Streptococcus. Among the Streptococcus group, anginosus is extremely rare to cause endocarditis, and there are only a few case reports available. We present a patient with S. anginosus bacteremia who subsequently got diagnosed with metastatic colon cancer along with aortic and mitral valve endocarditis

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.

Aortic valve endocarditis with root abscess causing superior vena cava obstruction: a case report

Background

To our knowledge, we report the first case of endocarditis with root abscess causing compressive superior vena cava (SVC) obstruction.

Case summary

An 84-year-old gentleman with previous tissue aortic valve replacement presented with fevers and systemic upset. Blood cultures grew Streptococcus anginosus and transoesophageal echocardiogram identified prosthetic valve vegetations with an associated root abscess. Antibiotics were commenced and referral made for surgical consideration. Several days into treatment the patient developed clinical signs of SVC obstruction and computed tomography demonstrated an enlarging root abscess with SVC compression. The patient was discussed with local cardiothoracic centres, but surgery was not an option primarily due to abscess size and vascular involvement. Priority moved from active to palliative treatment given no improvement with antibiotics, unsuitability for surgery, and patient discomfort. Within several weeks, symptoms/signs of SVC obstruction actually improved, likely due to collateral venous circulation formation and the patient was discharged home with palliative care input.

Discussion

There are previous reports of SVC obstruction related to infected SVC thrombus, indwelling intravascular devices, and para-aortic abscess, but none related to infective endocarditis. Streptococcus anginosus endocarditis is rare but often associated with abscess formation, and male gender, increasing age, and previous surgery are recognized risk factors.

Streptococcus intermedius masquerading as fungal infective endocarditis

Infective endocarditis remains an important clinical entity with an incidence of 1.7–10/100 000 person years (Marks et al, 2015). Despite improvements in health care, it still results in significant morbidity and in-hospital mortality approaches 16% (Marks et al, 2015). There are likely multiple causes including late diagnosis, poor response to therapy and the challenges in identifying the causative pathogen and instigating the correct treatment. This is particularly the case for causative organisms that are difficult to culture or identify using routine laboratory methods. An example of this is Streptococcus intermedius, which belongs to the S. milleri group along with other two species (S. anginosus group and S. constellatus). It is a commensal organism that can turn into an opportunistic pathogen (Whiley et al, 1992). It is a rare cause of infective endocarditis and may initially present with abscesses in the liver, spleen or brain which may mimic fungal infection (Woo et al, 2004; Rashid et al, 2007; Tran et al, 2008). Difficulty in identifying this organism has led to the development of molecular testing to aid diagnosis. To the authors' knowledge, there are very few cases in the literature of infective endocarditis caused by S. intermedius that have been confirmed using 16S polymerase chain reaction (Woo et al, 2004). This article describes a patient presenting with S. intermedius infective endocarditis which was diagnosed using this method.

Invasive pyogenic infection and infective endocarditis due to Streptococcus anginosus: A case report

RATIONALE

Streptococcus anginosus mostly colonizes the digestive and genitourinary system, including the oropharyngeal region. It commonly causes invasive pyogenic infection, but less likely causes infective endocarditis (IE).

PATIENT CONCERNS

An 18-year-old woman who had an underlying mitral valve prolapse without mitral regurgitation presented to our hospital with low-grade fever, left leg weakness, and left abdominal pain. She was diagnosed with brain infarction and microabscess as well as IE. The patient totally recovered after the 6-week course of intravenous antibiotics.

DIAGNOSIS

Brain magnetic resonance imaging revealed brain infarction and microabscess. Abdominal computed tomography revealed splenic and left renal infarction. Three sets of blood culture were positive for S anginosus. Transthoracic echocardiogram identified mitral valve prolapse with moderate eccentric mitral valve regurgitation, and a 0.3 × 0.6-cm vegetation was found on the left mitral valve. All of these results meet the modified Duke criteria.

INTERVENTIONS

The abdominal pain and left leg weakness were improving after 2 weeks of intravenous antibiotics treatment. No neurological sequelae were noted after completing the 6-week course of medical treatment.

OUTCOMES

The patient was successfully treated and discharged after completing the 6-week intravenous antibiotics treatment.

LESSONS

IE should be considered in young patients with native valve disease who have prolonged fever. Though S anginosus commonly causes invasive pyogenic infection, patients with native valve disease should be checked for IE.

Bacteremia caused by Slackia exigua: A report of two cases and literature review

Slackia exigua is an obligate anaerobic coccobacillus associated with dental infection, but rarely causes extraoral infection. We report two cases of monomicrobial bacteremia caused by S. exigua isolated from two institutions. The first case involved community-acquired bacteremia associated with pleural empyema in a 69-year-old man. The second case involved hospital-acquired bacteremia secondary to postoperative intra-abdominal abscess in a 73-year-old man with primary intestinal diffuse large B-cell lymphoma. S. exigua was finally identified by 16S ribosomal RNA gene sequencing analyses in both cases. In the first case, our attempts to identify the organism using commercial identification kits for anaerobes resulted in inaccurate identification as Gemella morbillorum. However, S. exigua was promptly identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry in the second case. The epidemiology and clinical characteristics of S. exigua extraoral infection remain unclear because of the limitations in accurate identification and because only 19 cases of extraoral S. exigua infection have been reported previously, including four cases of bacteremia. Physicians should focus on this species, which can cause community-acquired infections and spread via various routes even in patients with no comorbidities. Further studies are needed to clarify the clinical characteristics of extraoral S. exigua infections.

Infections Caused by Group C and G Streptococcus (Streptococcus dysgalactiae subsp. equisimilis and Others): Epidemiological and Clinical Aspects

Streptococci carrying serogroup C and G antigens, and in particular, Streptococcus dysgalactiae subsp. equisimilis (SDSE), are emerging human pathogens that are increasingly isolated from patients with a myriad of infections that range from mundane to life-threatening. SDSE is microbiologically similar to Streptococcus pyogenes. These streptococci frequently cause infections of the throat and skin and soft tissues. Moreover, they may invade the bloodstream and disseminate widely to many deep tissue sites, including the endocardium. Life-threatening invasive infections due to SDSE, including the streptococcal toxic shock syndrome, occur most frequently in patients with severe underlying medical diseases. Treatment with penicillin is adequate under most circumstances, but treatment failure occurs. SDSE may also be resistant to other antibiotic classes including tetracyclines, macrolides, and clindamycin. Most human infections caused by groups C and G streptococci are transmitted from person to person, but infections due to Streptococcus equi subsp. zooepidemicus (and, rarely, to S. equi subsp. equi) are zoonoses. Transmission of these latter species occurs by animal contact or by contamination of food products and has been associated with the development of poststreptococcal glomerulonephritis. Members of the Streptococcus anginosus group, usually classified with the viridans group of streptococci, are associated with a variety of pyogenic infections.

Rare Simultaneous Left and Right-Sided Native Valve Infective Endocarditis Caused by Rare Bacterium

Simultaneous left and right-sided native valve infective endocarditis (IE) is rare. Staphylococcus aureus was the predominant organism for bilateral IE. Shunt diseases are common risk factors of both-sided IE. Streptococcus anginosus (S. anginosus) is usually associated with pyogenic infections, but rarely a cause of IE. Here we present an extremely rare case of simultaneous left and right-sided native valve IE affecting the mitral and tricuspid valves caused by S. anginosus in an adult patient that has not been reported in the literature previously, particularly without the most frequent predisposing factors of IE. A 66-year-old man was admitted due to generalized fatigue, chills, malaise, and intermittent fevers for 1 year. A grade III-IV/VI systolic murmur at the mitral area and a III/VI systolic murmur at the tricuspid area were noted on physical examination. Laboratory evaluation revealed an elevated erythrocyte sedimentation rate and C-reactive protein level, and high fasting blood glucose. Blood culture was positive for S. anginosus. Echocardiography revealed vegetations in both sides of the heart: a large mitral valve vegetation with severe mitral regurgitation, as well as another vegetation on the tricuspid valve with moderate regurgitation. The case highlights a rare pathogen of both-sided IE, a rare presentation of S. anginosus infection, and several points worthy of note in echocardiography of IE.

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.

Isolated Streptococcus intermedius pulmonary nodules

•

S. intermedius infections can have extended hospital stays, but did not occur here.

•

Abscess/empyema formation, typical in S. intermedius infection, did not occur here.

•

A unique demographic of S. intermedius infection is shown, compared to literature.

Streptococcus intermedius, a member of the Streptococcal anginosus group of alpha-hemolytic streptococci, remains a notable infectious agent causing necrotizing pneumonia and abscesses. We report a case of a young male with pulmonary nodules found to have Streptococcus intermedius and no other underlying hepatic or dental history who was treated with ceftriaxone and avoided surgical intervention. A review of the literature reveals cases that are typically treated with a combined surgical and medical approach. These same cases often involve middle aged to elderly individuals who have a past history of tobacco use, alcoholic liver cirrhosis and/or poor dentition. This case stands out given the patient’s atypical presentation.

[Streptococcus milleri: An unusual cause of skull extensive osteomyelitis in an immunocompetent patient]

INTRODUCTION

Streptococcus milleri (Streptococcus anginosus, intermedius and constellatus) are commensal organisms, which can become pathogenic and cause infection with frequent abscess formation, local or metastatic extension. Osteomyelitis of the skull has been rarely reported in this type of infection.

CASE REPORT

Skull osteomyelitis due to Streptococcus milleri is reported in a 61-year-old immunocompetent man without any medical history, occurring 10 months after a head injury without any wound or complication at initial presentation. A progressive right parieto-occipital headache with worsening and increased acute phase reactants evoked a giant cell arteritis. After few days of corticosteroid therapy (0.5 mg/kg/day), diagnosis of subcutaneous abscess associated to an extensive osteomyelitis of the skull due to Streptococcus milleri was diagnosed. The outcome was favorable after drainage of one liter of pus, irrigation, debridement and antibiotherapy by amoxicillin for 8 weeks.

CONCLUSION

It is necessary to discuss the differential diagnosis of giant cell arteritis particularly when symptoms are unusual. Even a short-term corticosteroid therapy may dramatically exacerbate an undetected infection.

Complications of Acute Sinusitis in Children

OBJECTIVE: To review the demographic, microbiologic, and outcome data for children with complications of acute sinusitis.

STUDY DESIGN AND SETTING: Retrospective review of children admitted with complications of acute sinusitis from January 1995 to July 2002 to a tertiary care children's hospital.

RESULTS: One hundred four patients were reviewed with the following complications: orbital cellullitis (51), orbital abscesses (44), epidural empyemas (7), subdural empyemas (6), intracerebral abscesses (2), meningitis (2), cavernous sinus thrombosis (1), and Pott's puffy tumors (3). Sixty-six percent were males ( P < 0.001), and 64.4% presented from November to March ( P < 0.001). Patients with isolated orbital complications were younger than patients with intracranial complications (mean, 6.5 versus 12.3 years), had a shorter stay (mean, 4.2 versus 16.6 days), and had shorter duration of symptoms (mean, 5.4 versus 14.3 days; all P < 0.0001). Complete resolution was documented for 54/55 patients with restricted ocular motility, 7/8 with visual loss, 3/3 patients with a nonreactive pupil, 7/7 with neurological deficits, and 2/4 with seizures. The most common organism isolated was Streptococcus milleri (11/36 patients with surgical cultures). No mortalities occurred, and persistent morbidity occurred in 4 patients (3.8%).

CONCLUSIONS: Despite significant deficits on presentation, permanent morbidity was low. Streptococcus milleri is a common pathogen with complications of sinusitis in children.

Multiple Brain Abscesses due to Streptococcus anginosus: Prediction of Mortality by an Imaging Severity Index Score

An elderly patient with altered mental status, brain abscesses, ventriculitis, and empyemas died of septic shock and brain abscesses secondary to Streptococcus anginosus despite aggressive treatment. An imaging severity index score with a better prognostic value than the Glasgow coma scale predicted mortality in this patient.

A case of bacteremia caused by Dialister pneumosintes and Slackia exigua in a patient with periapical abscess

Dialister pneumosintes and Slackia exigua are both obligatory anaerobe and known to be associated with periodontal diseases and other oral infection. We report a case of blood stream infection caused by D. pneumosintes and S. exigua. This occurred in a 78-year-old female patient that presented with general weakness and fever. We revealed that she had a periapical abscess. The blood culture was positive for D. pneumosintes and S. exigua; however, identifying them was challenging. Ultimately, 16S rRNA sequencing was used to identify the organisms. The patient recovered after being treated with ceftriaxone and clindamycin. To the best of our knowledge, this is the first report of bacteremia caused by mixed infection of D. pneumosintes and S. exigua.

Infective endocarditis with left to right intracardiac fistula due to Streptococcus anginosus - a rare complication caused by an even rarer bacterium

Although infective endocarditis (IE) has been described in reports dating from the Renaissance, the diagnosis still challenges and the outcome often surprises. In the course of time, diagnostic criteria have been updated and validated to reduce misdiagnosis. Some risk factors and epidemiology have shown dynamic changes since degenerative valvular disease became more predominant in developed countries, and the mean age of the affected population increased. Despite streptococci have been being well known as etiologic agents, some groups, although rare, have been increasingly reported (e.g., Streptococcus milleri.) Intracardiac complications of IE are common and have a worse prognosis, frequently requiring surgical treatment. We report a case of a middle-aged diabetic man who presented with prolonged fever, weight loss, and ultimately severe dyspnea. IE was diagnosed based on a new valvular regurgitation murmur, a positive blood culture for Streptococcus anginosus, an echocardiographic finding of an aortic valve vegetation, fever, and pulmonary thromboembolism. Despite an appropriate antibiotic regimen, the patient died. Autopsy findings showed vegetation attached to a bicuspid aortic valve with an associated septal abscess and left ventricle and aortic root fistula connecting with the pulmonary artery. A large thrombus was adherent to the pulmonary artery trunk and a pulmonary septic thromboemboli were also identified.

Evaluation of 16SpathDB 2.0, an automated 16S rRNA gene sequence database, using 689 complete bacterial genomes

Interpretation of 16S rRNA sequences is a difficult problem faced by clinical microbiologists and technicians. In this study, we evaluated the updated 16SpathDB 2.0 database, using 689 16S rRNA sequences from 689 complete genomes of medically important bacteria. Among these 689 16S rRNA sequences, none was wrongly identified, with 35.8% reported as a single bacterial species having >98% identity with the query sequence (category 1), 63.9% reported as more than 1 bacterial species having >98% identity with the query sequence (category 2), 0.3% reported to the genus level (category 3), and none reported as no match (category 4). For the 16S rRNA sequences of non-duplicated bacterial species reported as category 1 or 2, the percentage of bacterial species reported as category 1 was significantly higher for anaerobic Gram-positive/Gram-negative bacteria than aerobic/facultative anaerobic Gram-positive/Gram-negative bacteria. 16SpathDB 2.0 is a user-friendly and accurate database for 16S rRNA sequence interpretation in clinical laboratories.

First report of brain abscess caused by a satelliting phenotypic variant of Helcococcus kunzii

Helcococcus kunzii was isolated from a brain abscess in a diabetic patient with cholesteatoma and demonstrated satellitism around Staphylococcus aureus in culture. This is the first reported case of severe central nervous system infection due to H. kunzii and the first description of a satelliting phenotypic variant of this organism.

Actinomyces naeslundii and Eikenella corrodens as rare causes of liver abscesses

A 48-year-old man with an unremarkable medical history was admitted with vague conditions of fever, chills, myalgias and malaise. Physical examination was remarkable for only scleral icterus. Laboratory evaluation revealed elevated aminotransferases, alkaline phosphatase and bilirubin. Imaging demonstrated two masses in the right lobe of his liver, which were ultimately drained and cultures demonstrated Actinomyces and Eikenella. He continued to have fever on broad-spectrum antibiotics until catheter drainage of the abscesses was performed. He was eventually discharged in improved condition on amoxicillin-clavulanate. His aminotransferases, alkaline phosphatase and bilirubin continued to improve and he remained afebrile and asymptomatic. A repeat CT 2 months after discharge demonstrated resolution of the abscesses. Actinomyces and Eikenella are rare causes of liver abscesses and treatment requires drainage and an extended course of antibiotics. The polymicrobial character typical of liver abscesses makes antibiotic therapy challenging when cultures reveal rare organisms such as Actinomyces and Eikenella.

Streptococcus hongkongensis sp. nov., isolated from a patient with an infected puncture wound and from a marine flatfish

A bacterium, HKU30T, was isolated from the infected tissue of a patient with wound infection after puncture by a fish fin. Cells are facultative anaerobic, non-spore-forming, non-motile, Gram-positive cocci arranged in chains. Colonies were non-haemolytic. The strain was catalase, oxidase, urease and Voges–Proskauer test negative. It reacted with Lancefield’s group G antisera and was resistant to optochin. It grew on bile aesculin agar and in 5 % NaCl. It was unidentified by three commercial identification systems. 16S rRNA gene sequence analysis indicated that the bacterium shared 98.2, 97.7, 97.4 and 97.1 % nucleotide identities with Streptococcus iniae , Streptococcus pseudoporcinus , Streptococcus parauberis and Streptococcus uberis , respectively. The DNA G+C content was 35.6±0.9 mol% (mean±sd). In view of the occupational exposure of the patient, an epidemiological study was performed to isolate the bacterium from marine fish. Two strains, with similar phenotypic and genotypic characteristics to those of HKU30T, were isolated from a three-lined tongue sole (Cynoglossus abbreviatus) and an olive flounder (Paralichthys olivaceus) respectively. Phylogenetic analysis of four additional housekeeping genes, groEL, gyrB, sodA and rpoB, showed that the three isolates formed a distinct branch among known species of the genus Streptococcus , being most closely related to S. parauberis (CCUG 39954T). DNA–DNA hybridization demonstrated ≤53.8 % DNA relatedness between the three isolates and related species of the genus Streptococcus . A novel species, Streptococcus hongkongensis sp. nov., is proposed. The type strain is HKU30T ( = DSM 26014T = CECT 8154T).

Subgingival microflora in inflammatory bowel disease patients with untreated periodontitis

OBJECTIVE

To analyze the subgingival microflora composition of inflammatory bowel disease (IBD) patients with untreated chronic periodontitis and compare them with systemically healthy controls also having untreated chronic periodontitis.

METHOD

Thirty IBD patients [15 with Crohn's disease (CD) and 15 with ulcerative colitis (UC)] and 15 control individuals participated in the study. All patients had been diagnosed with untreated chronic periodontitis. From every patient, subgingival plaque was collected from four gingivitis and four periodontitis sites with paper points. Samples from the same category (gingivitis or periodontitis) in each patient were pooled together and stored at -70 °C until analysis using a checkerboard DNA-DNA hybridization technique for 74 bacterial species.

RESULTS

Multiple-comparison analysis showed that the groups differed in bacterial counts for Bacteroides ureolyticus, Campylobacter gracilis, Parvimonas micra, Prevotella melaninogenica, Peptostreptococcus anaerobius, Staphylococcus aureus, Streptococcus anginosus, Streptococcus intermedius, Streptococcus mitis, Streptococcus mutans, and Treponema denticola (P<0.001). CD patients had significantly higher levels of these bacteria than UC patients either in gingivitis or in periodontitis sites (P<0.05). CD patients harbored higher levels of P. melaninogenica, S. aureus, S. anginosus, and S. mutans compared with controls both at gingivitis and at periodontitis sites (P<0.05). UC patients harbored higher levels of S. aureus (P=0.01) and P. anaerobius (P=0.05) than controls only in gingivitis sites.

CONCLUSION

Our study showed that even with similar clinical periodontal parameters, IBD patients harbor higher levels of bacteria that are related to opportunistic infections in inflamed subgingival sites that might be harmful for the crucial microbe-host interaction.

Multiple liver abscesses with isolation of Streptococcus intermedius related to a pyogenic dental infection in an immuno-competent patient

Introduction

Streptococcus intermedius - a member of the Streptococcus anginosus group - is part of the normal microbial flora of the oral cavity. Despite being regarded as a harmless apathogenic commensal, Streptococcus intermedius has been described to cause abscesses in various locations of the body.

Case Presentation

We report the clinical case and course of treatment of a 18-year-old male patient presenting with multiple hepatic abscesses associated with an untreated pyogenic dental infection.

Conclusion

Streptococcus intermedius can cause liver abscesses emerging from dental infectious foci even in previously healthy patients without underlying innate or aquired immunodeficiency. The case illustrates the potential danger and underestimated risk associated with untreated dental infections.

Human pathogenic streptococcal proteomics and vaccine development

Gram-positive streptococci are non-motile, chain-forming bacteria commonly found in the normal oral and bowel flora of warm-blooded animals. Over the past decade, a proteomic approach combining 2-DE and MS has been used to systematically map the cellular, surface-associated and secreted proteins of human pathogenic streptococcal species. The public availability of complete streptococcal genomic sequences and the amalgamation of proteomic, genomic and bioinformatic technologies have recently facilitated the identification of novel streptococcal vaccine candidate antigens and therapeutic agents. The objective of this review is to examine the constituents of the streptococcal cell wall and secreted proteome, the mechanisms of transport of surface and secreted proteins, and describe the current methodologies employed for the identification of novel surface-displayed proteins and potential vaccine antigens.

First report of spontaneous intrapartum Atopobium vaginae bacteremia

We report the first case of spontaneous intrapartum Atopobium vaginae bacteremia identified by 16S rRNA gene sequencing. The bacterium was misidentified by RapID ANA II, API Rapid ID 32A, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The likely source of bacteremia was the female genital tract. In invasive infections caused by A. vaginae, β-lactams and clindamycin are the antibiotics of choice, as most strains are resistant to metronidazole.

Clinical and microbiological characteristics of bacteremia caused by Eggerthella, Paraeggerthella, and Eubacterium species at a university hospital in Taiwan from 2001 to 2010

We describe 16 patients with bacteremia caused by Eggerthella lenta (n = 7), Paraeggerthella hongkongensis (n = 3), Eubacterium limosum (n = 4), Eubacterium callanderi (n = 1), and concomitant Eubacterium limosum/Eggerthella lenta (n = 1). Nine (56%) patients had polymicrobial bacteremia. The overall 60-day mortality rate was 19%, and all deaths occurred in patients with E. lenta bacteremia.

Automated identification of medically important bacteria by 16S rRNA gene sequencing using a novel comprehensive database, 16SpathDB

Despite the increasing use of 16S rRNA gene sequencing, interpretation of 16S rRNA gene sequence results is one of the most difficult problems faced by clinical microbiologists and technicians. To overcome the problems we encountered in the existing databases during 16S rRNA gene sequence interpretation, we built a comprehensive database, 16SpathDB (http://147.8.74.24/16SpathDB) based on the 16S rRNA gene sequences of all medically important bacteria listed in the Manual of Clinical Microbiology and evaluated its use for automated identification of these bacteria. Among 91 nonduplicated bacterial isolates collected in our clinical microbiology laboratory, 71 (78%) were reported by 16SpathDB as a single bacterial species having >98.0% nucleotide identity with the query sequence, 19 (20.9%) were reported as more than one bacterial species having >98.0% nucleotide identity with the query sequence, and 1 (1.1%) was reported as no match. For the 71 bacterial isolates reported as a single bacterial species, all results were identical to their true identities as determined by a polyphasic approach. For the 19 bacterial isolates reported as more than one bacterial species, all results contained their true identities as determined by a polyphasic approach and all of them had their true identities as the "best match in 16SpathDB." For the isolate (Gordonibacter pamelaeae) reported as no match, the bacterium has never been reported to be associated with human disease and was not included in the Manual of Clinical Microbiology. 16SpathDB is an automated, user-friendly, efficient, accurate, and regularly updated database for 16S rRNA gene sequence interpretation in clinical microbiology laboratories.

Leptotrichia hongkongensis sp. nov., a novel Leptotrichia species with the oral cavity as its natural reservoir

A straight, non-sporulating, Gram-variable bacillus (HKU24(T)) was recovered from the blood culture of a patient with metastatic breast carcinoma. After repeated subculturing in BACTEC Plus Anaerobic/F blood culture broth, HKU24(T) grew on brucella agar as non-hemolytic, pinpoint colonies after 96 h of incubation at 37 degrees C in an anaerobic environment and aerobic environment with 5% CO2. Growth was enhanced with a streak of Staphylococcus aureus. HKU24(T) was non-motile and catalase-negative, but positive for alkaline phosphatase, beta-glucosidase, and alpha-glucosidase. It hydrolyzed phenylphosphonate and reduced resazurin. 16S rRNA, groEL, gyrB, recA, and rpoB sequencing showed that HKU24(T) occupies a distinct phylogenetic position among the Leptotrichia species, being most closely related to Leptotrichia trevisanii. Using HKU24(T) groEL, gyrB, recA, and rpoB gene-specific primers, fragments of these genes were amplified from one of 20 oral specimens. Based on phenotypic and genotypic characteristics, we propose a new species, Leptotrichia hongkongensis sp. nov., to describe this bacterium.

Osteoradionecrosis contains a wide variety of cultivable and non-cultivable bacteria

Background

Direct microscopy, anaerobic culture and DNA–DNA hybridization have previously demonstrated an association between microorganisms and osteoradionecrosis (ORN). The purpose of our study was to use culture independent molecular techniques to detect bacteria in necrotic bone lesions of the mandible after radiation therapy.

Design

Bacterial DNA was extracted from eight deep medullar specimens from resected mandibles (six cases), including one patient with relapse. 16S rRNA genes were PCR amplified, cloned, transformed into Escherichia coli and sequenced to determine species identity and closest relatives.

Results

From the analysis of 438 clones, 59 predominant species were detected, 27% of which have not been cultivated. The predominant species detected from radionecrotic mandibles were Campylobacter gracilis, Streptococcus intermedius, Peptostreptococcus sp. oral clone FG014, uncultured bacterium clone RL178, Fusobacterium nucleatum, and Prevotella spp. The study demonstrated intersubject variability of the bacteria present in ORN. In contrast to the diverse bacterial profile detected in primary infection, only a few members of the oral indigenous flora were identified from the relapse case.

Conclusions

Diverse bacterial profiles in specimens of ORN in marrow spaces of the mandible were detected by culture independent molecular techniques. To better understand the pathogenesis and to improve the therapy of the infection, detection of all members of the complex bacterial flora associated with ORN is necessary.

Prospective surveillance of streptococcal sore throat in a tropical country

BACKGROUND

Acute rheumatic fever and rheumatic heart disease cause a high burden of disease in Fiji and surrounding Pacific Island countries, but little is known about the epidemiology of group A streptococcal (GAS) pharyngitis in the region. We designed a study to estimate the prevalence of carriage of beta-hemolytic streptococci (BHS) and the incidence of BHS culture-positive sore throat in school aged children in Fiji.

METHODS

We conducted twice-weekly prospective surveillance of school children aged 5 to 14 years in 4 schools in Fiji during a 9-month period in 2006, after an initial phase of pharyngeal swabbing to determine the prevalence of BHS carriage.

RESULTS

We enrolled 685 children. The prevalence of GAS carriage was 6.0%, while the prevalence of group C streptococcal (GCS) and group G streptococcal (GGS) carriage was 6.9% and 12%, respectively. There were 61 episodes of GAS culture-positive sore throat during the study period equating to an incidence of 14.7 cases per 100 child-years (95% CI, 11.2-18.8). The incidence of GCS/GGS culture-positive sore throat was 28.8 cases per 100 child-years (95% CI, 23.9-34.5). The clinical nature of GAS culture-positive sore throat was more severe than culture-negative sore throat, but overall was mild compared with that found in previous studies. Of the 101 GAS isolates that emm sequence typed there were 45 emm types with no dominant types. There were very few emm types commonly encountered in industrialized nations and only 9 of the 45 emm types found in this study are emm types included in the 26-valent GAS vaccine undergoing clinical trials.

CONCLUSIONS

GAS culture-positive sore throat was more common than expected. Group C and group G streptococci were frequently isolated in throat cultures, although their contribution to pharyngeal infection is not clear. The molecular epidemiology of pharyngeal GAS in our study differed greatly from that in industrialized nations and this has implications for GAS vaccine clinical research in Fiji and other tropical developing countries.

Streptococcus intermedius causing infective endocarditis and abscesses: a report of three cases and review of the literature

Background

Streptococcus intermedius is a member of the Streptococcus anginosus group. Clinical disease with S. intermedius is characterized by abscess formation and rarely endocarditis. Identification of Streptococcus intermedius is difficult, leading to the development of molecular methods to more accurately identify and characterize this organism.

Case presentation

Over a period of 6 months we encountered three cases of invasive Streptococcus intermedius infection presenting as hepatic abscesses, brain abscess, and endocarditis. We confirmed our microbiologic diagnosis through 16S sequencing and found a common virulence gene in each case.

Conclusion

Our report illustrates three different clinical manifestations due to Streptococcus intermedius infection that can be encountered in healthy individuals in a community hospital setting. To our knowledge, this is the first case of Streptococcus intermedius endocarditis confirmed by 16S sequencing analysis. The use of molecular methods may allow a better understanding of the epidemiology and pathogenesis of this organism.

Bacteremia associated with toothbrushing and dental extraction

BACKGROUND

Antibiotic prophylaxis recommendations for the prevention of infective endocarditis are based in part on studies of bacteremia from dental procedures, but toothbrushing may pose a greater threat. The purpose of this study was to compare the incidence, duration, nature, and magnitude of endocarditis-related bacteremia from single-tooth extraction and toothbrushing and to determine the impact of amoxicillin prophylaxis on single-tooth extraction.

METHODS AND RESULTS

In this double-blind, placebo-controlled study, 290 subjects were randomized to (1) toothbrushing, (2) single-tooth extraction with amoxicillin prophylaxis, or (3) single-tooth extraction with identical placebo. Blood was drawn for bacterial culturing and identification at 6 time points before, during, and after these interventions. The focus of our analysis was on bacterial species reported to cause infective endocarditis. We identified 98 bacterial species, 32 of which are reported to cause endocarditis. Cumulative incidence of endocarditis-related bacteria from all 6 blood draws was 23%, 33%, and 60% for the toothbrushing, extraction-amoxicillin, and extraction-placebo groups, respectively (P<0.0001). Significant differences were identified among the 3 groups at draws 2, 3, 4, and 5 (all P<0.05). Amoxicillin resulted in a significant decrease in positive cultures (P<0.0001).

CONCLUSIONS

Although amoxicillin has a significant impact on bacteremia resulting from a single-tooth extraction, given the greater frequency for oral hygiene, toothbrushing may be a greater threat for individuals at risk for infective endocarditis.

Identification of species of viridans group streptococci in clinical blood culture isolates by sequence analysis of the RNase P RNA gene, rnpB

OBJECTIVES

Viridans group streptococci (VGS) cause severe diseases such as infective endocarditis and septicaemia. Genetically, VGS species are very close to each other and it is difficult to identify them to species level with conventional methods. The aims of the present study were to use sequence analysis of the RNase P RNA gene (rnpB) to identify VGS species in clinical blood culture isolates, and to compare the results with the API 20 Strep system that is based on phenotypical characteristics.

METHODS

Strains from patients with septicaemia or endocarditis were analysed with PCR amplification and sequence analysis of the rnpB gene. Clinical data were registered as well.

RESULTS

One hundred and thirty two VGS clinical blood culture isolates from patients with septicaemia (n=95) or infective endocarditis (n=36) were analysed; all but one were identified by rnpB. Streptococcus oralis, Streptococcus sanguinis and Streptococcus gordonii strains were most common in the patients with infective endocarditis. In the isolates from patients with haematological diseases, Streptococcus mitis and S. oralis dominated. In addition in 76 of the isolates it was possible to compare the results from rnpB analysis and the API 20 Strep system. In 39/76 (51%) of the isolates the results were concordant to species level; in 55 isolates there were no results from API 20 Strep.

CONCLUSION

Sequence analysis of the RNase P RNA gene (rnpB) showed that almost all isolates could be identified. This could be of importance for evaluation of the portal of entry in patients with septicaemia or infective endocarditis.

AI-2 quorum sensing affects antibiotic susceptibility in Streptococcus anginosus

OBJECTIVES

The concern over rising antibiotic resistance necessitates exploration of alternative approaches in antimicrobial therapy. Bacterial communities use the auto-inducer 2 (AI-2) quorum sensing signal at a specific threshold level for intra- and interspecies communication in order to regulate virulence behaviour. AI-2 signal production occurs in bacteria that possess a luxS homologue. In this study, we investigate for the first time the association between AI-2 signalling and susceptibility to antibiotics.

METHODS

Streptococcus anginosus wild-type and its isogenic luxS mutant SA001 were exposed to erythromycin and ampicillin. Susceptibility to erythromycin and ampicillin was determined by measuring the cell density and viability. Complementation assays were conducted by exposing the mutant to wild-type supernatant or to the AI-2 precursor molecule dihydroxy-2,3-pentanedione (DPD).

RESULTS

Disruption of luxS in S. anginosus resulted in a mutant with increased susceptibility to erythromycin and ampicillin. Supernatant from S. anginosus wild-type partially restored growth of SA001 in the presence of the two antibiotics. DPD restored growth of the luxS mutant in the presence of erythromycin and ampicillin to values similar to that of S. anginosus wild-type.

CONCLUSIONS

Our results indicate that luxS-based AI-2 communication is associated with antibiotic susceptibility. Targeting the AI-2 signal communication may present a novel approach in antimicrobial therapy.

Medical and surgical management of subperiosteal orbital abscess secondary to acute sinusitis in children

OBJECTIVE

To evaluate the presentations and outcomes of pediatric subperiosteal orbital abscesses (SPOA) secondary to acute sinusitis.

STUDY DESIGN

Case series

SETTING

Tertiary children's hospital.

PATIENTS

Forty-three admissions diagnosed with SPOA by clinical presentation and contrast enhanced computed tomography (CECT) were retrospectively reviewed.

MAIN OUTCOME MEASURES

Clinical presentations, CECT dimensions, treatment, outcomes, and microbiology.

RESULTS

Eighteen/43 (42%) patients resolved their infection with medical management only, including five children older than nine. Twenty-five/43 (58%) children underwent surgical drainage. Purulence was identified in 22 of 25 surgical patients, and the most common organism was Streptococcus milleri (7 patients). Compared to 22 patients with drained purulence, the 18 patients with abscesses managed medically had significant differences for: chemosis in 2/18 (11.1%) versus 14/22 (63.6%, p=0.001), proptosis in 10/18 (55.6%) versus 20/22 (90.9%, p=0.025), elevated intraocular pressure (IOP) in 0/18 (0%) versus 11/22 (50%, p<0.001), severe restriction of extraocular movements in 1/18 (5.6%) versus 12/22 (54.5%, p=0.002), and length of stay (4.3 versus 5.8 days, p=0.038). The dimensions of medial SPOA managed medically were significantly smaller on CECT compared to surgically drained purulent SPOA: width (0.25 versus 1.46cm, p<0.001), height (0.73 versus 1.35cm, p=0.002), and length (1.1 versus 1.86cm, p=0.004). Persistent morbidities occurred in no patients managed medically and in 2/25 (8%) managed surgically.

CONCLUSIONS

Children with small medial SPOA without significant ocular signs may be managed medically with favorable outcomes. Proposed criteria for medical management of medial SPOA include: (1) normal vision, pupil, and retina; (2) no ophthalmoplegia; (3) IOP<20mmHg; (4) proptosis of 5mm or less; and (5) abscess width of 4mm or less. In contrast to prior series, older children with SPOA were managed successfully with medical therapy.

Bacterial Profile and Burden of Periodontal Infection in Subjects With a Diagnosis of Acute Coronary Syndrome

BACKGROUND

Periodontitis has been identified as a potential risk factor in cardiovascular diseases. It is possible that the stimulation of host responses to oral infections may result in vascular damage and the inducement of blood clotting. The aim of this study was to assess the role of periodontal infection and bacterial burden as an explanatory variable to the activation of the inflammatory process leading to acute coronary syndrome (ACS).

METHODS

A total of 161 consecutive surviving cases admitted with a diagnosis of ACS and 161 control subjects, matched with cases according to their gender, socioeconomic level, and smoking status, were studied. Serum white blood cell (WBC) counts, high- and low-density lipoprotein (HDL/LDL) levels, high-sensitivity C-reactive protein (hsC-rp) levels, and clinical periodontal routine parameters were studied. The subgingival pathogens were assayed by the checkerboard DNA-DNA hybridization method.

RESULTS

Total oral bacterial load was higher in the subjects with ACS (mean difference: 17.4x10(5); SD: 10.8; 95% confidence interval [CI]: 4.2 to 17.4; P<0.001), and significant for 26 of 40 species including Porphyromonas gingivalis, Tannerella forsythensis, and Treponema denticola. Serum WBC counts, hsC-rp levels, Streptococcus intermedius, and Streptococcus sanguis, were explanatory factors to acute coronary syndrome status (Nagelkerke r2=0.49).

CONCLUSION

The oral bacterial load of S. intermedius, S. sanguis, Streptococcus anginosus, T. forsythensis, T. denticola, and P. gingivalis may be concomitant risk factors in the development of ACS.

Globicatella bacteraemia identified by 16S ribosomal RNA gene sequencing

BACKGROUND

Globicatella are streptococcus-like organisms that have been rarely isolated from clinical specimens. Their epidemiology and clinical significance remain largely unknown.

AIMS

To describe two cases of Globicatella bacteraemia identified by 16S ribosomal RNA (rRNA) gene sequencing.

METHODS

Two unidentified streptococcus-like bacteria isolated from blood cultures of patients were subject to 16S rRNA gene sequencing.

RESULTS

Two cases of Globicatella bacteraemia were identified by 16S rRNA gene sequencing. In the first case, a gram positive coccus was isolated from the blood culture of an 80 year old woman with diabetes mellitus and nosocomial sepsis, who died the day after developing the bacteraemia. The bacterium was unidentified by conventional phenotypic tests, the Vitek (gram positive identification) and the ATB expression (ID32 Strep) systems. In the second case, a similar bacterium was isolated from the blood culture of a 92 year old woman with polymicrobial acute pyelonephritis complicated by septic shock, who subsequently recovered after antibiotic treatment. 16S rRNA gene sequencing of the two isolates showed 0.5% nucleotide difference from that of G. sulfidifaciens and 0.7% nucleotide difference from that of G. sanguinis, indicating that they were Globicatella species.

CONCLUSIONS

Because Globicatella is rarely encountered in clinical microbiology laboratories, it may have been overlooked or misidentified in these cases. 16S rRNA gene sequencing is a useful tool to better characterise the epidemiology and clinical significance of Globicatella.

Brain abscess in children

OBJECTIVES

Brain abscess is a serious life-threatening complication of several diseases. The objective of this study was to look at the clinical profile of patients, predisposing conditions, microbiology and outcome of children suffering from brain abscess.

METHODS

Thirty children aged less than 15 years were reviewed. There were 15 males and 15 females. The mean age of presentation was 5.6+/-4.4 years.

RESULTS

The duration of illness at the time of admission was 17.6+/-24.6 days. Typically patients presented with fever, vomiting, headache and seizures. The predisposing conditions found were cyanotic congenital heart disease in 11 (37%) of children, meningitis in 6 (20%), septicemia in 7 (23%) and no underlying cause was found in 5 (17%) children. The most common microbe in children with cyanotic congenital heart disease was of the Streptococcus milleri group (52%). Computerized tomography confirmed the diagnosis and the most common location of the abscess was the parietal lobe of the cerebral hemisphere. All abscesses were large, more than 2 cm in diameter and were aspirated surgically. Excision was performed in 6 children. Five children expired, one due to a intracranial bleeding and the others due to severe cerebral edema and tentorial herniation. Complications were seen in 20 children and 16 had sequelae, hemiparesis in 11 and seizure disorder in 5.

CONCLUSION

Brain abscess is a serious infection with poor outcome if diagnosed late. Delayed surgical drainage has high morbidity and mortality. The threshold for diagnosis should be low, particularly in children with a predisposing condition like cyanotic congenital heart disease.

Clinical, phenotypic, and genotypic evidence for Streptococcus sinensis as the common ancestor of anginosus and mitis groups of streptococci

In 2002, we reported the discovery of a novel species of viridans streptococcus, Streptococcus sinensis. Recently, we reported the isolation of two more strains of S. sinensis. Clinically, S. sinensis is a definite cause of infective endocarditis, a characteristic mainly pertaining to the mitis group of streptococci. Phenotypically, two of the three S. sinensis isolates were Lancefield group F, a characteristic of the anginosus group. However, none of the three strains possess the caramel smell typical of this group of streptococci. Biochemically, S. sinensis was identified in 56% of the time as members of the anginosus group, and in 33% of the time as members of the mitis group. These clinical and phenotypic properties should be governed by the presence/absence or expressivity of particular genes in the S. sinensis genome. Genotypically, phylogenetic analysis using 16S rRNA gene sequences showed that S. sinensis branched out as the first branch in the anginosus group, implying that it is the ancestor of the other members of this group. However, the bootstrap value for S. sinensis clustered with members of the anginosus group is only 47%, meaning that it is often not clustered with members of this group, but the mitis group. Furthermore, the differences in the 16S rRNA gene sequences between S. sinensis and Streptococcus intermedius (3.7%) and those between S. sinensis and Streptococcus gordonii (3.6%) are almost the same. All these indicated that it is very likely that S. sinensis is the common ancestor of the anginosus and mitis groups of streptococci. Complete genome sequencing of S. sinensis and comparative genomics studies on the S. sinensis genome and genomes of members in the anginosus and mitis groups should reveal clues to the underlying genotypic differences that govern the different phenotypic properties of the two groups of streptococci, such as why streptococci of the anginosus group are prone to cause abscess formation but not infective endocarditis as compared to other viridans streptococci.

Culture results of heart valves resected because of streptococcal endocarditis: insights into duration of treatment to achieve valve sterilization

OBJECTIVES

To analyse the culture results of heart valves removed following streptococcal endocarditis in order to gain insight into the duration of treatment required for valve sterilization.

PATIENTS AND METHODS

Retrospective review of 131 episodes of streptococcal endocarditis: 94 due to alpha-haemolytic streptococci; 15 due to beta-haemolytic streptococci; 10 due to nutritionally deficient streptococci; eight due to the Streptococcus anginosus group and four due to Streptococcus pneumoniae. Patients had their valves removed during antimicrobial treatment. Culture results were analysed with respect to duration of treatment before surgery.

RESULTS

For alpha-haemolytic streptococci, 17 (18%) valves were culture-positive and 77 (82%) culture-negative after a median (range) of 4 (1-20) and 16 (4-58) days of treatment, respectively, P < 0.001. For beta-haemolytic streptococci, two valves (13%) were culture-positive; both patients had received < or = 4 days of treatment. Four patients (40%) with nutritionally deficient streptococci were culture-positive, and had received < or = 8 days of treatment. For the S. anginosus group, two valves (25%) were culture-positive; both patients had received < or = 4 days of treatment before operation. Overall, only one of 131 (0.8%) valves was culture-positive after 14 days of treatment. All valves infected with beta-haemolytic streptococci, nutritionally deficient streptococci and the S. anginosus group, who were treated for more than 8 days before surgery, were culture-negative.

CONCLUSIONS

Our findings support current treatment guidelines for endocarditis caused by alpha-haemolytic streptococci. We suggest that the recommended duration of treatment for endocarditis resulting from other streptococci may be excessive and treatment trials evaluating 2 and 4 week regimens are justified.