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

Invasive Streptococcus intermedius Infections in Children: Two Cases from a Pediatric Infectious Diseases Unit in Italy

In recent years, an increasing number of reports have described invasive infections caused by bacteria from Streptococcus anginosus group (SAGs). S. intermedius seems to be more related with pleuropulmonary infections and abscess of the brain and deep soft tissues, and it is more likely to cause suppurative and non-bacteremic infections compared to other members of the same genus. We present two clinical cases of invasive S. intermedius infections in pediatric patients: a liver abscess case and a pansinusitis case associated with bilateral otomastoiditis and parapharyngeal abscess complicated by acute mediastinitis, thrombophlebitis of the cavernous sinus, and thrombosis of the cranial tract of the ipsilateral jugular vein. In both cases, prompt broad-spectrum antibiotic therapy and operative drainage of the collections resulted in a good clinical response with full recovery.

Novel Use of Metagenomic Next-Generation Sequencing in Diagnosing Streptococcus intermedius Meningitis and Ventriculitis: A Case Report and Literature Review

Background

Streptococcus intermedius is a commensal microflora commonly found in various mucosal sites in the respiratory, gastrointestinal, and genitourinary tracts. It causes invasive suppurative infections including liver and brain abscesses along with thoracic empyema. However, it rarely causes meningitis without abscess formation.

Case Presentation

A 56-year-old immunocompetent man who presented with fever and headache. Bacterial meningitis was confirmed using cerebrospinal fluid analysis. Magnetic resonance imaging of the brain revealed leptomeningitis and ventriculitis. However, conventional methods, such as microbiological culture failed to identify the causative pathogens. Metagenomic next-generation sequencing of cerebrospinal fluid revealed the presence of S. intermedius. It allowed us the optimal treatment for him. The patient underwent antibiotic treatment with 6-week duration of ceftriaxone administration accompanied by surgical intervention, resulting in a favorable prognosis.

Conclusion

Herein, we report a rare case of meningitis and ventriculitis caused by S. intermedius using metagenomic next-generation sequencing. The patient recovered well after antibiotic treatment and surgery. We present this rare case and summarize previous studies to remind clinicians that timely identification of the pathogen and optimal treatment are crucial for management of S. intermedius-induced infections.

Paroxysmal sympathetic hyperactivity syndrome caused by Streptococcus intermedius meningoencephalitis in children: a case report and literature review

Introduction and importance

Paroxysmal sympathetic hyperactivity (PSH) syndrome often occurs with severe traumatic brain injury. However, it can also occur during infections, such as severe bacterial meningoencephalitis in children. Streptococcus intermedius is an aggressive, virulent, opportunistic pathogen. This species can cause meningoencephalitis in children, as reported in a few cases.

Case information

A five-year-old boy with no relevant past medical history was admitted to a hospital because of a fever and progressive disturbance of consciousness. His head computed tomography scan and magnetic resonance imaging revealed extensive brain damage and an intraventricular abscess. A next-generation sequencing technology test performed on his cerebrospinal fluid revealed that the child's meningoencephalitis was caused by S. intermedius. During treatment, the child had clinical manifestations such as fever, tachycardia, tachypnea, diaphoresis, and hypertension. Changes in muscle tone and abnormal posture, which were misdiagnosed as epilepsy at the early treatment stage, were also observed; however, anti-epileptic treatment was ineffective. The child was diagnosed with PSH and received the appropriate treatment, and his symptoms eventually improved.

Conclusions

To our knowledge, this is the first case report on PSH induced by S. intermedius meningoencephalitis. Early identification, diagnosis, and treatment of PSH are crucial.

Innumerable Culture-Negative Intracranial Abscesses in an Immunocompetent Young Male Diagnosed by 16s rRNA Gene Sequencing

Here, we present a case of a healthy young man with an initial presentation concerning for infectious encephalitis later found on neuroimaging to have extensive intracranial lesions. Pathological analysis of these lesions was consistent with a bacterial intraparenchymal abscess; however, cultures were negative for a causative organism. Results of gene sequencing from an abscess sample were consistent with Streptococcus intermedius infection. Streptococcus intermedius, a β-hemolytic gram-positive species of the Streptococcus anginosus group (SAG), is known to possess several virulence factors that promote abscess formation.

Misidentified Metastases: Diagnosing and Managing Pyogenic Liver Abscesses in a Breast Cancer Survivor

BACKGROUND Pyogenic liver abscesses are collections of pus of varying sizes within the liver. They are rare and often overlooked in developed countries, and if left untreated, they can be life-threatening. Therefore, early detection and treatment are crucial for favorable outcomes. Due to the atypical presentation, a high level of suspicion is necessary, as seen in our patient's case. CASE REPORT This report pertains to a 76-year-old woman who was diagnosed with sepsis resulting from multiple hepatic abscesses. Initially, the abscesses were mistaken for metastatic breast cancer liver disease due to her history of breast cancer in remission for 3 years. However, further imaging and biopsy revealed the initial diagnosis to be incorrect. She had initially presented with nonspecific abdominal pain and diarrhea. The initial computed tomography (CT) scan of the abdomen indicated the development of extensive hepatic lesions, thought to be associated with breast cancer, but subsequent magnetic resonance imaging (MRI) suggested liver abscesses. Ultrasound-guided aspiration confirmed the presence of liver abscesses, and subsequent culture of the aspirate revealed the growth of Streptococcus intermedius. The patient responded well to a 4-week course of antibiotic therapy. CONCLUSIONS This case report reviews the clinical presentation, risk factors, diagnosis, and management of multiple pyogenic liver abscesses, and shows the importance of using sound clinical reasoning in addressing diagnostic challenges of this nature.

Complete genome sequence of Streptococcus intermedius strain XH2169

Here, we report the complete genome sequence of Streptococcus intermedius strain XH2169 isolated from a blood sample in China. The genome comprises a single circular chromosome with a length of 1,944,282 bp. It harbored 1,891 coding gene sequences, 16 rRNA genes, 60 tRNA genes, and 3 noncoding RNA genes.

Multi-Omics Analysis Reveals Dietary Fiber's Impact on Growth, Slaughter Performance, and Gut Microbiome in Durco × Bamei Crossbred Pig

Dietary fiber (DF) is an important nutrient component in pig's diet that remarkably influences their growth and slaughter performance. The ability of pigs to digest DF depends on the microbial composition of the intestinal tract, particularly in the hindgut. However, studies on how DF alters the growth and slaughter performance of pigs by shaping the gut microbial composition and metabolites are still limited. Therefore, this study aimed to investigate the effects of DF on microbial composition, functions, and metabolites, ultimately altering host growth and slaughter performance using Durco × Bamei crossbred pigs supplemented with 0%, 10%, 17%, and 24% broad bean silage in the basic diet. We found that the final weight, average daily gain, fat, and lean meat weight significantly decreased with increasing DF. Pigs with the lowest slaughter rate and fat weight were observed in the 24% fiber-supplemented group. Gut microbial communities with the highest alpha diversity were formed in the 17% fiber group. The relative abundance of fiber-degrading bacteria, bile acid, and succinate-producing bacteria, including Prevotella sp., Bacteroides sp., Ruminococcus sp., and Parabacteroides sp., and functional pathways, including the butanoate metabolism and the tricarboxylic acid [TCA] cycle, significantly increased in the high-fiber groups. The concentrations of several bile acids significantly decreased in the fiber-supplemented groups, whereas the concentrations of succinate and long-chain fatty acids increased. Our results indicate that a high-fiber diet may alter the growth and slaughter performance of Durco × Bamei crossbred pigs by modulating the composition of Prevotella sp., Bacteroides sp., Ruminococcus sp., Parabacteroides sp., and metabolite pathways of bile acids and succinate.

Case Report: An Unusual Case of Lemierre's Syndrome Presenting as Influenza B-Induced Myositis Complicated by Streptococcus intermedius Infection

Lemierre's syndrome (LS) is a rare and severe complication primarily associated with the bacteria Fusobacterium necrophorum and characterized by an oropharyngeal infection leading to bacteremia and septic thrombophlebitis. We present a case of an 89-year-old patient with a history of hypertension who initially presented with type B influenza infection and neck pain. She subsequently developed a neck abscess with thrombosis of the internal jugular vein. We believe this to be the first reported case in the literature of LS secondary to Streptococcus intermedius presenting after infection with type B influenza. As more atypical LS cases emerge, it is becoming increasingly clear that this condition can manifest in a number of ways. This unique case highlights the importance of considering LS as a differential diagnosis for patients of all ages presenting with neck pain and Streptococcus intermedius infection.

Extensive Parapharyngeal Abscess in a 4-Month-Old Infant

Parapharyngeal abscess in an infant is a very rare condition. We present the case of a 4-month-old girl with large masses on the neck's left side. Computed tomography showed an extensive parapharyngeal abscess. Left tonsillectomy was performed under general anesthesia from a transoral approach, followed by an incision and evacuation of the abscess from the parapharyngeal space. Microbiological analysis identified a massive occurrence of Streptococcus intermedius.

Pediatric Community-Acquired Brain Abscesses: A Single-center Retrospective Study

The European Society for Clinical Microbiology and Infectious Diseases recommends 3rd generation cephalosporins and metronidazole for empirical treatment of community-acquired brain abscesses. In 53 retrospectively analyzed pediatric patients with community-acquired brain abscesses at a German University Hospital Staphylococcus aureus was identified as a relevant pathogen (21%). Therefore, it may be reasonable to cover S. aureus when selecting empirical therapy.

A Report of Two Cases of Meningoencephalitis Caused by Streptococcus intermedius

Objective

In this paper, we analyzed the clinical data of patients with meningoencephalitis caused by Streptococcus intermedius to understand better the clinical characteristics of the disease and recommend auxiliary diagnostic mode as well as treatment experience.

Methods

We reviewed the clinical data of two patients admitted to our department in 2019 with meningoencephalitis caused by S. intermedius.

Results

Two female patients were examined, one of whom had a history of radiotherapy for nasopharyngeal carcinoma while the other had no underlying disease. These two patients were admitted with symptoms of meningoencephalitis. Cerebrospinal fluid examinations revealed elevated levels of leukocytes and protein. After treatment with meropenem, the condition improved for a brief time, but then worsened with a decline in mental status and limb movement. Blood and cerebrospinal fluid cultures demonstrated the absence of pathogenic bacteria, while genome sequencing of cerebrospinal fluids revealed the presence of S. intermedius. Cranial magnetic resonance imaging revealed multiple cerebral abscesses (CAs). After coadministration of linezolid as an anti-infective, clinical symptoms gradually improved, and the CAs shrank on follow-up imaging. The condition exhibited a pattern of improvement-deterioration-improvement.

Conclusion

Meningoencephalitis caused by S. intermedius is complex and prone to fluctuation and formation of multiple CAs. The definitive clinical diagnosis of this disease can be aided by genome sequencing technology, and early clarification of the etiology combined with the use of potent antibiotics is effective.

Challenging Diagnosis of Streptococcus intermedius-Associated Empyema in an Immunocompetent Adult: A Case Report and Literature Review

The significance of Streptococcus intermedius in infectious diseases, especially pleural infections, is gaining recognition. While traditional risk factors like dental procedures and immunosuppression remain pivotal in differential diagnosis, there is an emerging recognition of unconventional clinical presentations and risk factors linked to infections by S. intermedius. This shift compels medical professionals to broaden their diagnostic and therapeutic strategies, underscoring the intricate and evolving nature of managing infections associated with this opportunistic bacterium. We describe the case of a 48-year-old immunocompetent woman with untreated hypertension who experienced a 15-day episode of right-sided chest pain, which worsened with a sudden onset of dyspnea, yet her daily activities remained unaffected. Physical examination suggested a pleuropulmonary syndrome due to significant pleural effusion, with a computed tomography (CT) scan of the lungs revealing about 50% effusion on the right side. Laboratory tests indicated elevated inflammatory markers. Ultrasound-guided thoracentesis extracted purulent fluid compatible with empyema, necessitating the placement of a pleural drain and multiple pleural cavity lavages using alteplase, which led to the removal of substantial infected fluid. Culture of the pleural fluid identified S. intermedius, which was pansusceptible. Treatment with intravenous ceftriaxone was administered, resulting in a favorable clinical outcome. This case highlights the critical nature of recognizing atypical clinical presentations and managing complex bacterial infections in the pleural space.

Rapidly Progressing Intramedullary Spinal Cord Abscess: A Case Report

Intramedullary spinal cord abscess is a rare and severe infectious disease characterized by devastating neurological deficits. We report a case of cervical intramedullary spinal cord abscess in a 74-year-old diabetic male with a 3-day history of neck pain and weakness in the right lower extremity. Magnetic resonance imaging revealed a ring-shaped contrast lesion in C3-C6 of the cervical spinal cord with extensive edema. Further, 1 day after admission, he became comatose (Glasgow Coma Scale E1VtM1), and a computed tomography head scan revealed hydrocephalus. Despite emergency ventricular drainage, the patient's level of consciousness remained unchanged. Magnetic resonance imaging performed 1 day after surgery revealed bilateral intracranial extension of the abscess into the thalamus and caudate nucleus. The patient died 19 days after admission. Our report is the first case of extensive brain abscess development over a short period. Based on our experience, prompt administration of antibiotics and emergency abscess drainage of the cervical cord (and ventricular drainage, if necessary) are recommended in cases of neurological deterioration in patients with cervical intramedullary spinal cord abscess.

Identification of mutations resulting in derepression of the intermedilysin gene by sequential mutagenesis of its promoter region in Streptococcus intermedius

Streptococcus intermedius secretes the human-specific cytolysin intermedilysin (ILY), a crucial factor in the pathogenicity of this bacterium. Previously, we reported that a lactose phosphotransferase repressor (LacR) represses ily expression, and that its mutation increases ILY production. Interestingly, UNS40, a strain isolated from a liver abscess, produces high levels of ILY despite the absence of mutations in the lacR promoter and coding regions. Our results showed that a G > A mutation at the -90th position from the transcription start point in the UNS40 ily promoter region increased hemolytic activity and decreased the binding ability to LacR. To elucidate the regions involved in the repression of ily expression, we generated mutant strains, in which point or deletion mutations were introduced into the ily promoter region, and then compared their hemolytic activity. Among the point mutations, -120 C > A and -90 G > A and their flanking mutations increased hemolytic activity. These results indicated that these mutations may increase the virulence of S. intermedius.

Necrotizing fasciitis and fatal septic shock associated with Streptococcus constellatus

Streptococcus constellatus is usually a benign, commensal bacteria but has increased incidence in blood cultures and abscesses. This pathogenic involvement is most prevalent in individuals with underlying medical conditions, such as solid tumors and type 2 diabetes mellitus, as well as in cases of community-acquired infections. We report a 43-year-old male with a right medial thigh ulcer and necrotic scrotal skin. The wound culture from surgical debridement grew Streptococcus constellatus, and histology was consistent with stage III necrotizing fasciitis. Regardless of etiology, the mortality rate of patients with necrotizing fasciitis is greatly decreased with early intervention and thorough surgical debridement.

Clinical characteristics and mortality rates of bacteremia caused by Streptococcus anginosus group: A retrospective study of 84 cases at a tertiary hospital in South Korea

The Streptococcus anginosus group (SAG) is a subgroup of viridans streptococci comprising three species: S. anginosus, S. constellatus, and S. intermedius. SAG usually resides in the oral cavity and colonizes the throat, and the gastrointestinal and genitourinary tracts. SAG can form abscesses in various parts of the body; however, the clinical features of SAG infection are not clear. Here, we reviewed the medical records of all SAG bacteremia patients aged over 18 years who were diagnosed between January 2010 and December 2021 at a tertiary university hospital. We then compared clinical characteristics, source of infection, need for surgical or interventional treatment, and 28-day mortality rates among each species of SAG. Differences in percentages between groups were compared using a proportion test, and differences between mean values were assessed using the Kruskal-Wallis test with post-hoc Bonferroni correction. In total, 84 cases of SAG bacteremia (40 S. anginosus cases, 31 S. constellatus cases, and 13 S. intermedius cases) were identified. The most common comorbidity was diabetes mellitus (n = 26, 31%), and the most common source was hepatobiliary infection (n = 30, 35.7%). Polymicrobial bacteremia was observed in 22.6% (19/84) of cases. Twenty-eight day mortality due to S. anginosus bacteremia was 12.5%; no deaths were reported in the S. constellatus and S. intermedius groups. However, the difference among the groups was not significant (p = 0.054). Hepatobiliary infection was the most common source of SAG bacteremia. In addition, S. anginosus bacteremia resulted in more severe disease and higher mortality rates than S. constellatus or S. intermedius bacteremia.

Esophageal Perforation Presenting Initially as Multiple Brain Abscesses Secondary to Streptococcus intermedius

Brain abscess is a life-threatening infection that can occur secondary to contiguous or hematogenous spread. Several underlying conditions can lead to brain abscesses, such as dental infection, otitis media, sinusitis, and immunosuppression. Esophageal perforation leading to brain abscesses is extremely rare. We report a rare case of a 32-year-old man who presented to the emergency department with progressive headaches and upper-extremity weakness. Upon further evaluation, computed tomography (CT) revealed multiple brain abscesses secondary to Streptococcus intermedius infection. The patient eventually underwent esophagogastroduodenoscopy (EGD), which showed a perforation in the middle third of the esophagus. This case highlights the importance of considering esophageal perforation as a predisposing condition for brain abscesses.

Streptococcus intermedius: From a Normal Oral Commensal to a Life-Threatening Organism

Subdural empyema is a collection of pus in the subdural space between the dura mater and the arachnoid. It carries very high morbidity and mortality as it can spread anywhere in the brain; however, the risk can be mitigated with appropriate surgical and medical intervention. Being protected by the skull, cranial infections are usually preceded by a significant risk factor, either an external invader such as skull fractures secondary to trauma, penetrating injury, prior surgery, or, more commonly, in more than 50% of cases, due to spread of an internal infection such as ear or sinus infections. Anaerobic and aerobic bacteria can cause subdural empyema. Both gram-positive and gram-negative bacteria are notorious for developing this kind of infection; for example, different groups of gram-positive streptococci and staphylococci, gram-negative Haemophilus influenza, and other gram-negative bacilli can cause subdural empyema. While streptococci are more frequent with sinus infection causing subdural empyema, staphylococci are associated with skin invasion secondary to either head trauma or cranial surgery. Streptococcus intermedius is a gram-positive alpha-hemolytic pathogen belonging to the larger Streptococcus anginosus group that itself is a subgroup from viridans streptococci, aka Streptococcus milleri. Streptococcus intermedius is an oral commensal flora and is considered to be a low-virulence bacteria in immunocompetent patients but can be associated with significant morbidity and mortality. Subdural empyema tends to occur more often in immunocompromised patients such as diabetic patients, those with human immunodeficiency virus infection, and those using immunosuppressive medications. The clinical course ranges from indolent to fulminant. The size and location of the abscess play a role in clinical presentation. Headache is the most common presenting symptom, but patients can also present with fever, nausea, seizure, or altered mental status. Diagnosis can be obtained with CT and MRI scans of the brain. Prompt drainage of the abscess and lengthy antibiotics improve the prognosis significantly. Our case highlights a rare origin of subdural empyema from the direct spread of a skin abscess.

Comparison of endoscopic sinus sampling versus intracranial sampling for microbiological diagnosis of intracranial infection in children: a case series and literature review

INTRODUCTION

Intracranial infection is often associated with contiguous sinus infection, with Streptococcus intermedius being the most common pathogen. Microbiological assessment is possible via sinus or intracranial sampling. While a sinus approach is minimally invasive, it is not clear whether this yields definitive microbiological diagnosis leading to optimized antimicrobial therapy and avoidance of intracranial surgery.

METHODS

A retrospective review of a prospectively collected electronic departmental database identified patients between 2019 and 2022. Further demographic and microbiological information was obtained from electronic patient records and laboratory management systems.

RESULTS

Thirty-one patients were identified with intracranial subdural and/or epidural empyema and concurrent sinus involvement during the 3-year study period. The median age of onset was 10 years with a slight male predominance (55%). All patients had intracranial sampling with 15 patients undergoing sinus sampling in addition. Only 1 patient (7%) demonstrated identical organism(s) grown from both samples. Streptococcus intermedius was the most common pathogen in intracranial samples. Thirteen patients (42%) had mixed organisms from their intracranial cultures and 57% of samples undergoing bacterial PCR identified additional organisms, predominantly anaerobes. Sinus samples had a significant addition of nasal flora and Staphylococcus aureus which was rarely grown from intracranial samples. Of concern, 7/14 (50%) of sinus samples did not identify the main intracranial pathogen diagnosed on intracranial culture and additional PCR. Literature review identified 21 studies where sinus drainage was used to treat intracranial empyemas, with only 6 authors reporting concurrent microbiology results. This confirmed our cohort to be the largest comparative study in the current literature. No center has observed a greater than 50% concordance in microbiological diagnoses.

CONCLUSION

Endoscopic sinus surgery may have therapeutic benefit, but it is not an appropriate approach for microbiological diagnosis in pediatric subdural empyemas. High rates of contaminating nasal flora can lead to misdiagnosis and inappropriate treatment. Routine addition of 16S rRNA PCR to intracranial samples is recommended.

Clinical Reasoning: An Older Woman With Headaches and Lethargy After a Fall

In this case, a 77-year-old woman presented with generalized weakness, difficulty ambulating, lethargy, loss of appetite, and headaches after a mechanical fall. This case discusses the management of acute neurologic emergencies such as subdural hematoma, status epilepticus, and bacterial meningitis. Potential etiologies for stroke and CNS infection are highlighted. Readers are led through the diagnostic approach to a patient presenting with a complex array of neurologic symptoms causing rapid clinical decompensation.

An Ex-Vivo Model for Investigating Bacterial Extrusion from Infected Root Canals during Masticatory Function

INTRODUCTION

The extrusion of bacteria from infected root canals may lead to increase in symptoms, expansion of periapical lesions, and contribution to systemic diseases. The aim of this study is to investigate a potential proof-of-concept model to study the extent to which bacteria can escape from infected root canals under dynamic loading (simulated chewing).

METHODS

The study was completed in 2 experiments performed at 2 institutions. Biofilms of Streptococcus intermedius in the first experiment and S. intermedius and Actinomyces naeslundii were allowed to grow in root canals of single-rooted extracted teeth for 3 weeks. The roots of the teeth were suspended in a small chamber containing dental transport medium and were mounted on a lower sample holder of a chewing simulator. In the experimental group, simulated chewing cycles equivalent to 1 year of function were conducted, and then bacterial migration was quantified and compared with stationary teeth.

RESULTS

All experimental samples of the loading group revealed bacterial penetration in both experiments. Several of the unloaded samples revealed no bacterial penetration. In the first experiment, a significantly higher number of bacteria were able to escape into the periapex of the loaded group compared with the unloaded group (P = .017). In the second experiment, there was no significant difference between the 2 bacterial species used in the amount of extruded bacteria; however, there was a highly significant effect for occlusal loading (P = .0001).

CONCLUSIONS

The potential for occlusal forces to enhance bacterial extrusion from infected root canals should be further explored.

Hepatic Abscess in Inflammatory Bowel Disease: A Systematic Scoping Review of an Overlooked Entity

Background

Liver abscess is one of the hepatobiliary manifestations of inflammatory bowel disease (IBD) that has been scarcely described in the literature.

Objectives

To conduct a scoping review to provide a detailed description of the occurrence of hepatic abscess in patients with IBD and summarize the observed clinical features.

Methodology

Searches were carried out using relevant keywords in Medline (via PubMed) and Web of Science from inception until June 13, 2022. Only articles that reported the occurrence of hepatic abscess in patients with IBD were included.

Results

Forty-eight publications (40 case reports and 8 case series) were included, representing 73 patients with IBD who were radiologically or intraoperatively diagnosed with hepatic abscess. Patients with Crohn's disease were more predisposed to developing hepatic abscess than patients with ulcerative colitis (79.5% vs. 20.5%, respectively). Furthermore, pyogenic liver abscess was found to be more prevalent (57.9%) compared with aseptic (38.7%) and amebic (3.2%) abscesses. No clear relation was found between death or prolonged hospital stay in terms of the clinical presentation or management plan, as mortality was reported in different age groups with different managements.

Conclusion

To date, there is no consensus regarding the appropriate management of hepatic abscess as an extraintestinal manifestation of IBD. However, the condition shares several features with liver abscess diagnosed among the general population.

Osteomyelitis caused by Streptococcus intermedius in immunocompetent adults - a case report and systematic literature review

Hematogenous osteomyelitis caused by Streptococcus intermedius is rare, particularly in immunocompetent adults. The aim of this paper is to provide an overview of the clinical presentation, prognosis as well as treatment of this disease, with the focus on immunocompetent adults. Six medical literature libraries were searched to identify studies reporting on Streptococcus intermedius induced hematogenous osteomyelitis in immunocompetent adults. In addition, we presented a case of a 44-year-old man from our institution that is illustrative for this disease. Four case reports describing four patients were identified by this systematic literature review. Hence, the data of five patients (including our case) were assessed. The most common presenting symptom was localised pain, followed by fever. Portal entries were found in two patients (general periodontitis and necrotic dentition). The localisations of osteomyelitis were diverse: femoral (two patients), lumbar spine (two patients), and the iliac bone (one patient). Treatment strategies varied strongly, but antibiotics (penicillins) were administered in each case, and two patients underwent surgical debridement. Follow-up ranged from 2 weeks to more than 6 months; one patient died from septic shock. Only a very limited number of immunocompetent adults with Streptococcus intermedius induced hematogenous osteomyelitis have been described. Based on the available data, we summarised the clinical presentation, prognosis as well as treatment of hematogenous osteomyelitis caused by Streptococcus intermedius in this patient population.

Streptococcus intermedius Brain Abscess with Lung Abscess and Aortic Valve Endocarditis: A Case Report and Literature Review

Streptococcus intermedius is frequently associated with brain and liver abscesses, while pleuropulmonary infections are considered rarer. Even less frequent is the association of lung and brain abscesses due to this agent with infective endocarditis. We describe the case of a 40-year-old man complaining of cough, fever, and headache who was diagnosed with a brain abscess due to S. intermedius, a concomitant lung abscess, and aortic native valve endocarditis. He was treated with surgical drainage of the brain abscess and a 4-week course of intravenous ceftriaxone, followed by oral amoxicillin/clavulanate, obtaining healing of the lesions without relapse of the infection.

Clinical features of Streptococcus intermedius infection in children: a case series study

Introduction

Streptococcus intermedius is an opportunistic pathogen associated with prolonged hospital stays and high mortality rates in adults. However, little is currently known about the clinical features of Streptococcus intermedius infection in children.

Methods

This retrospective case series study included 40 children diagnosed with Streptococcus intermedius, confirmed through bacterial cultures or high-throughput sequencing. Antibiotic resistance was assessed through susceptibility testing. The site and clinical manifestations were evaluated for all patients.

Results

The common infection sites were the abdominal cavity, skin and soft tissue, intracranial, and invasive pulmonary, with the abdominal cavity being the most frequently affected. The drug susceptibility test showed 100% sensitivity to ceftriaxone, levofloxacin, chloramphenicol, vancomycin, and linezolid, 92.6% sensitivity to penicillin, 73.3% resistance to erythromycin, and 76.7% resistance to clindamycin. Besides antibiotic therapy, surgical intervention or pus drainage was often necessary. Lung imaging of four patients revealed pulmonary abscesses, nodules, or encapsulated pleura. Two cases yielded positive culture results, while three were identified as positive through high-throughput nucleotide sequencing of pleural effusion.

Discussion

In children with Streptococcus intermedius infection, emphasis should be placed on the risk of pus or abscess formation. In cases of pulmonary abscess and pleural effusion, especially in male children, Streptococcus intermedius should be suspected even if the culture is negative. Improvements in high-throughput nucleotide sequencing are required to reduce misdiagnosis rates.

Characterization of Lung and Oral Microbiomes in Lung Cancer Patients Using Culturomics and 16S rRNA Gene Sequencing

Recently, microbiota dysbiosis in lung cancer has attracted immense attention. Studies on lung microbes are mostly based on sequencing, which has left the potentially functional bacteria with extremely low abundance uncovered. In this study, we characterized and compared the lung and oral cavity microbiotas using culturomics and 16S rRNA gene sequencing. Of the 198 bacteria identified at the species level from bronchoalveolar lavage fluid (BALF) samples, Firmicutes was predominant (39.90%). Twenty bacterial species isolated from BALF samples were present in at least half of the patients and were also highly abundant in oral samples. Of all isolated strains, Streptococcus and Veillonella were highly dominant. The abundance of Prevotella and Veillonella decreased from the oral cavity to the lung, whereas that of Pseudomonas increased. Linear discriminant analysis effect size demonstrated that Prevotella was more abundant in the healthy samples than in the cancerous ones, which is in accordance with the isolation of Prevotella oralis only from the healthy group using culturomics. Moreover, Gemella sanguinis and Streptococcus intermedius were isolated only from the non-small-cell lung cancer (NSCLC) group, and 16S rRNA gene sequencing showed that they were higher in the NSCLC than in the small-cell lung cancer group. Furthermore, while Bacillus and Castellaniella were enriched in lung adenocarcinoma, Brucella was enriched in lung squamous cell carcinoma. Overall, alterations were observed in the microbial community of patients with lung cancer, whose diversity might be site and pathology dependent. Using culturomics and 16S rRNA gene amplicon sequencing, this study has provided insights into pulmonary and oral microbiota alterations in patients with lung cancer. IMPORTANCE The relationship between lung microbiota and cancer has been explored based on DNA sequencing; however, culture-dependent approaches are indispensable for further studies on the lung microbiota. In this study, we applied a comprehensive approach combining culturomics and 16S rRNA gene amplicon sequencing to detect members of the microbiotas in saliva and BALF samples from patients with unilateral lobar masses. We found alterations in the microbial community of patients with lung cancer, whose diversity might be site and pathology dependent. These features may be potential bacterial biomarkers and new targets for lung cancer diagnosis and treatment. In addition, a lung and oral microbial biobank from lung cancer patients was established, which represents a useful resource for studies of host-microbe interactions.

Risk factors of brain abscess in neonatal meningitis: a propensity score-matched study

Brain abscess is a rare but life-threatening complication of meningitis. The purpose of this study was to identify clinical features and potentially relevant factors of brain abscess in neonates with meningitis. This study was a propensity score-matched case-control study of neonates with brain abscess and meningitis in a tertiary pediatric hospital between January 2010 and December 2020. A total of 16 neonates with brain abscess were matched to 64 patients with meningitis. Demography, clinical characteristics, laboratory results, and pathogens were collected. Conditional logistic regression analyses were performed to identify the independent risk factors associated with brain abscess. The most common pathogen we found in the brain abscess group was Escherichia coli. Risk factors of brain abscess were identified: multidrug-resistant bacterial infection (OR, 11.204; 95% CI, 2.315-54.234; p = 0.003), C-reactive protein (CRP) > 50 mg/L (OR, 11.652; 95% CI, 1.799-75.470; p = 0.010).  Conclusion: The risk factors of brain abscess are multidrug-resistant bacterial infection and CRP > 50 mg/L. Monitoring the level of CRP is essential. Bacteriological culture and rational use of antibiotics are necessary for the prevention of MDR bacterial infection as well as the occurrence of brain abscess. What is Known: • Morbidity and mortality of neonatal meningitis have declined, but brain abscess associated with neonatal meningitis is still life-threatening. What is New: • This study investigated relevant factors related to brain abscess. • It is important for neonatologists to perform prevention, early identification, and appropriate interventions for neonates with meningitis.

Septic Arthritis of the Atlanto-Occipital Joint Caused By S. Intermedius in a 5-Year-Old Girl: A Case Report

Septic arthritis of the atlanto-occipital joint caused by Streptococcus intermedius is extremely rare. We present the first case report of this entity in a fully immunocompetent 5-year-old girl. The magnetic resonance imaging and blood tests were consistent with septic arthritis, so she started empirical antibiotic therapy. Septic arthritis should be excluded in children with torticollis, fever and neck pain.

Robust cross-cohort gut microbiome associations with COVID-19 severity

Although many recent studies have examined associations between the gut microbiome and COVID-19 disease severity in individual patient cohorts, questions remain on the robustness across international cohorts of the biomarkers they reported. Here, we performed a meta-analysis of eight shotgun metagenomic studies of COVID-19 patients (comprising 1,023 stool samples) and 23 > 16S rRNA gene amplicon sequencing (16S) cohorts (2,415 total stool samples). We found that disease severity (as defined by the WHO clinical progression scale) was associated with taxonomic and functional microbiome differences. This alteration in gut microbiome configuration peaks at days 7-30 post diagnosis, after which the gut microbiome returns to a configuration that becomes more similar to that of healthy controls over time. Furthermore, we identified a core set of species that were consistently associated with disease severity across shotgun metagenomic and 16S cohorts, and whose abundance can accurately predict disease severity category of SARS-CoV-2 infected subjects, with Actinomyces oris abundance predicting population-level mortality rate of COVID-19. Additionally, we used relational diet-microbiome databases constructed from cohort studies to predict microbiota-targeted diet patterns that would modulate gut microbiota composition toward that of healthy controls. Finally, we demonstrated the association of disease severity with the composition of intestinal archaeal, fungal, viral, and parasitic communities. Collectively, this study has identified robust COVID-19 microbiome biomarkers, established accurate predictive models as a basis for clinical prognostic tests for disease severity, and proposed biomarker-targeted diets for managing COVID-19 infection.

A case report of multiple abscesses caused by Streptococcus intermedius

Streptococcus intermedius is a beta-hemolytic, non-motile, catalase-negative, gram-positive member of the Streptococcus anginosus group. When compared to other members of this group like S. anginosus and Streptococcus constellatus, S. intermedius infections are more substantial. In this case, we present a 47-year-old male patient who was found to have S. intermedius abscesses in his lungs, liver, and brain. The treatment of choice for these abscesses is a combination of drainage, surgery, and antibiotic therapy.

Clinical Microbial Identification of Severe Oral Infections by MALDI-TOF Mass Spectrometry in Stockholm County: an 11-Year (2010 to 2020) Epidemiological Investigation

Growing evidence suggests that oral infections can modify the course of systemic diseases. To date, epidemiological data on microbial oral infections are scarce. Here, we performed a comprehensive analysis of the trend and microbial diversity in oral infection specimens referred for clinical microbiology analysis from 2010 to 2020. The microbes were isolated by culture and were identified via matrix-assisted laser desorption ionization-time of flight mass spectrometry technology (MALDI-TOF MS) throughout the study period. A total of 1,014 referred samples from dental clinics in Stockholm County with dentoalveolar abscesses and jaw osteomyelitis being the main reason were identified. Overall, the microbial composition was dominated by Firmicutes (51%), followed by Bacteroidetes (19%), Proteobacteria (12%), and Actinobacteria (5%). At the genus level, Streptococcus spp. (36%), Prevotella spp. (18%), and Staphylococcus spp. (11%) were among the most frequently reported. Interestingly, a strong increase in trend was noted for Streptococcus anginosus, Streptococcus mitis, Streptococcus sanguinis, Eikenella corrodens, Actinomyces spp., Aggregatibacter aphrophilus, Staphylococcus epidermidis, and Granulicatella adiacens during the study time (R = 0.66 to 0.89, P < 0.05), and a minor increase was noted for Enterococcus faecalis and Klebsiella spp., whereas steady levels were noted for most of the others. The present study shows the diversity of bacteria that have been involved in dental infections during the last decade in the capital of Sweden, as well as the emerging oral microbiota trend, with clear clinical implications on the oral-systemic link. IMPORTANCE Oral diseases and associated microbes are a risk factor for systemic diseases and can change the courses of these diseases. To date, epidemiological data on microbial oral infections are scarce, and longitudinal reports are lacking. We present for the first time the microbial composition of severe oral bacterial infections determined via the MALDI-TOF mass spectrometry technique in a comprehensive study between 2010 and 2020 (11 years) in Stockholm County. The trend and microbial diversity of oral infections were analyzed on referred clinical microbiological samples and were processed by standardized protocols. Trend increase was noted for Streptococcus anginosus, Streptococcus mitis, Streptococcus sanguinis, Eikenella corrodens, Actinomyces spp., Aggregatibacter aphrophilus, Staphylococcus epidermidis, Granulicatella adiacens, Enterococcus faecalis, and Klebsiella spp. Our results provide new insights into the diversity and trend of oral microbiota that were involved in serious oral infections over the past decade in the capital of Sweden and may influence the oral-systemic link.

Pyogenic brain abscess associated with an incidental pulmonary arteriovenous malformation

Pulmonary arteriovenous malformations (PAVMs) are rare and often asymptomatic vascular anomalies that can be associated with serious neurological consequences due to right-to-left shunting. We report a case of a woman in her 80s without substantial medical history who presented with a headache, weakness and personality changes, and was found to have a pyogenic brain abscess requiring emergent neurosurgical evacuation. The abscess grew oral flora, suspected to have reached the brain via an incidentally discovered PAVM. With drainage and antibiotics, the patient achieved a full recovery and the PAVM was embolised. To our knowledge, this is the oldest presentation of a PAVM-associated brain abscess in the published literature. Older patients may present without the typical signs and symptoms of a given illness, which complicates accurate diagnosis and treatment. Primary care physicians can help facilitate timely care and positive clinical outcomes.

Virulence factors of Streptococcus anginosus - a molecular perspective

Streptococcus anginosus together with S. constellatus and S. intermedius constitute the Streptococcus anginosus group (SAG), until recently considered to be benign commensals of the human mucosa isolated predominantly from oral cavity, but also from upper respiratory, intestinal, and urogenital tracts. For years the virulence potential of SAG was underestimated, mainly due to complications in correct species identification and their assignment to the physiological microbiota. Still, SAG representatives have been associated with purulent infections at oral and non-oral sites resulting in abscesses formation and empyema. Also, life threatening blood infections caused by SAG have been reported. However, the understanding of SAG as potential pathogen is only fragmentary, albeit certain aspects of SAG infection seem sufficiently well described to deserve a systematic overview. In this review we summarize the current state of knowledge of the S. anginosus pathogenicity factors and their mechanisms of action.

Streptococcus intermedius Acute Meningitis in an Immunocompetent Child

Streptococcus intermedius is a commensal bacterium increasingly associated with brain abscesses. It can infect the brain through a direct extension of an inflammatory process or a hematogenous route. Meningitis due to this pathogen is sporadic and has not been described in children before. We report a case of an immunocompetent 6-year-old boy who developed bacterial meningitis due to S. intermedius .

Septic shock from multiple intra-abdominal Streptococcus constellatus abscesses unamenable to percutaneous drainage

Streptococcus constellatus are gram-positive cocci belonging to the Streptococcus milleri group that have a propensity to cause bacteremia and abscesses, especially in immunocompromised patients. Here, we report the case of a 39-year-old male who was initially admitted to the hospital for diabetic ketoacidosis. During the hospitalization, he developed sepsis and blood cultures grew Streptococcus constellatus. CT imaging revealed multiple hepatic abscesses. A periapical abscess of the left mandibular central incisor found on CT Scan of face was identified as the likely source of infection. IR-guided drainage was performed however the patient went on to develop septic shock despite attempted source control and IV antibiotic therapy. Repeat imaging showed persistent hepatic abscesses in addition to new intraperitoneal abscesses necessitating exploratory laparotomy, drainage and abdominal washout. Fluid cultures grew Streptococcus constellatus and common enteric flora. Our report highlights the need for high clinical suspicion in cases of Streptococcus constellatus bacteremia to obtain diagnostic imaging for any abscess formation. Prolonged antibiotic therapy is a must and imaging guided or surgical drainage may be needed.

Multifocal brain abscesses caused by invasive Streptococcus intermedia: A case report

Multifocal brain abscesses caused by invasive Streptococcus intermedia are relatively rare. Here, we present a 67-year-old male was admitted to the hospital for unconsciousness and fever. The computed tomography (CT) examination showed multiple intracranial space-occupying and “cavity-like” changes in the right lower lung. The examination of cerebrospinal fluid (CSF) was consistent with typical bacterial meningitis, CSF analyses revealed leukocytosis (10,300 × 10⁶/L), elevated protein levels (140.39 mg/dL), decreased glucose levels (0.27 mmol/L), and normal chloride concentration level (120.2 mmol/L), however, pathogens were not detected in the cultures. Then, the CSF and sputum samples were analyzed using meta-genomic next-generation sequencing (mNGS), and S. intermedia was detected in both samples. We adjusted the use of antibiotics according to the results of mNGS in time. After anti-infective treatment, the patient achieved good treatment results in a very short time. This case highlights the mNGS can identify pathogens of brain abscess, and provide strong evidence for clinical diagnosis and treatment strategy.

A maternal higher-complex carbohydrate diet increases bifidobacteria and alters early life acquisition of the infant microbiome in women with gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with considerable imbalances in intestinal microbiota that may underlie pathological conditions in both mothers and infants. To more definitively identify these alterations, we evaluated the maternal and infant gut microbiota through the shotgun metagenomic analysis of a subset of stool specimens collected from a randomized, controlled trial in diet-controlled women with GDM. The women were fed either a CHOICE diet (60% complex carbohydrate/25% fat/15% protein, n=18) or a conventional diet (CONV, 40% complex carbohydrate/45% fat/15% protein, n=16) from 30 weeks' gestation through delivery. In contrast to other published studies, we designed the study to minimize the influence of other dietary sources by providing all meals, which were eucaloric and similar in fiber content. At 30 and 37 weeks' gestation, we collected maternal stool samples; performed the fasting measurements of glucose, glycerol, insulin, free fatty acids, and triglycerides; and administered an oral glucose tolerance test (OGTT) to measure glucose clearance and insulin response. Infant stool samples were collected at 2 weeks, 2 months, and 4-5 months of age. Maternal glucose was controlled to conventional targets in both diets, with no differences in Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). No differences in maternal alpha or beta diversity between the two diets from baseline to 37 weeks' gestation were observed. However, women on CHOICE diet had higher levels of Bifidobacteriaceae, specifically Bifidobacterium adolescentis, compared with women on CONV. Species-level taxa varied significantly with fasting glycerol, fasting glucose, and glucose AUC after the OGTT challenge. Maternal diet significantly impacted the patterns of infant colonization over the first 4 months of life, with CHOICE infants showing increased microbiome alpha diversity (richness), greater Clostridiaceae, and decreased Enterococcaceae over time. Overall, these results suggest that an isocaloric GDM diet containing greater complex carbohydrates with reduced fat leads to an ostensibly beneficial effect on the maternal microbiome, improved infant gut microbiome diversity, and reduced opportunistic pathogens capable of playing a role in obesity and immune system development. These results highlight the critical role a maternal diet has in shaping the maternal and infant microbiome in women with GDM.

The first case of Streptococcus intermedius brain abscess with hemophagocytic histiocytosis

Background

Hemophagocytic lymphohistiocytosis (HLH) is a rare but potentially life-threatening immune syndrome associated with an excessive systemic inflammatory response. Viral infection caused HLH is the most common secondary HLH, but there are relatively few reports of HLH caused by bacterial infection. The present study is the first case of HLH caused by Streptococcus intermedia meningitis.

Case presentation

The patient is an 11-year-old and 9-month-old boy. The main symptoms are fever, headache, and vomiting. The imaging finding of the brain is cerebritis and brain abscess. The cerebrospinal fluid (CSF) routine test showed increased nucleated cells, but the smear and culture of CSF were negative. The metagenomics next-generation sequencing (mNGS) of CSF detected Streptococcus intermedius, and the body temperature of the children returned to normal after antibiotic treatment according to etiology. One week later, the child developed fever again, with Kawasaki disease-like manifestations. After high-dose immunoglobulin therapy, the body temperature returned to normal again. The routine blood test showed a progressive decrease in leukocytes and platelets, and bone marrow biopsy detected histiocytes phagocytosed blood cells. Then infection-associated hemophagocytic syndrome (IAHS) was diagnosed, high-dose methylprednisolone and sequential therapy were given and the patient’s recovery was encouraging.

Conclusions

Our case shows that HLH can also be secondary to Streptococcus intermediate infection, and early bone marrow biopsy is the golden standard for HLH diagnosis. mNGS can improve the detection sensitivity for pathogens when traditional pathogenic tests are negative. Conventional chemotherapy regimens may not be required for IAHS when high-dose glucocorticoids and immunoglobulin therapy are effective.

Streptococcus intermedius Bacteremia and Pyogenic Liver Abscess in a Patient With No Risk Factors

This case report depicts a 39-year-old male with no significant past medical history who was admitted for fever of unknown origin and sepsis. He was then found to have Streptococcus intermedius bacteremia and pyogenic liver abscess. The treatment course was complicated by pleural empyema leading to readmission. The case presented here adds to the medical literature, where a clear underrepresentation has been noted, and outlines a unique case of S. intermedius liver abscess complicated by pleural empyema in a patient without significant medical history, risk factors, or typical physical exam findings.

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.

Intramedullary spinal cord abscess associated with right-to-left shunt via right superior vena cava draining into left atrium: A case report

RATIONALE

Intramedullary spinal cord abscess (ISCA) is a rare but treatable bacterial infection of the central nervous system, and the etiology in no less than 40% of the cases is cryptogenic. Although a few cases of ISCA in individuals with a right-to-left shunt (RL shunt) have been reported, only few arguments focused on the association between RL shunt and ISCA have been provoked. The right superior vena cava (RSVC) draining into the left atrium (LA) is an uncommon systemic venous anomaly that results in an RL shunt, and this anomaly causes several types of neurological complication such as stroke or brain abscess. We report the first case of ISCA associated with RSVC-LA RL shunt.

PATIENT CONCERNS

A 36-year-old man developed progressive paraparesis, dysuria, and spontaneous pain in the lumbar region and lower extremities. Spinal magnetic resonance imaging revealed an intramedullary lesion extended from Th12 to L2 with ring-shaped gadolinium enhancement. Cerebrospinal fluid (CSF) study exhibited a marked pleocytosis, and CSF culture grew Streptococcus intermedius. Cardiovascular computed tomography angiography identified RSVC-LA RL shunt, which caused transient acute cardiac syndrome due to air embolus.

DIAGNOSES

The patient was diagnosed with ISCA associated with an RSVC-LA RL shunt.

INTERVENTIONS

The patient was treated with a combination of intravenous administration of meropenem and vancomycin in a daily dose of 6 and 2.5 g, respectively, followed by intravenous administration of ampicillin in a daily dose of 750 mg. The intravenous antibiotic therapy was continued for 37 days.

OUTCOMES

A favorable neurological outcome was obtained by the intravenous antibiotic therapy, and recurrence of infection was prevented by continuous oral antibiotic therapy for 18 months.

LESSONS

With a literature review of ISCA associated with RL shunt, we insist that screening for RSVC-LA is beneficial to patients who are diagnosed with cryptogenic ISCA as its identification leads to appropriate preventive therapy.

An Eight Year Clinico-Microbiological Retrospective Study on Brain Abscesses in India

Background:

Intracranial abscesses have been a diagnostic and therapeutic challenge since time immemorial for both the microbiologists and the neurosurgeons. There is paucity of detailed studies documenting the infecting organism causing brain abscesses in South India.

Aims:

The study aimed at identifying and assessing the prevalence of aerobic, anaerobic bacteria and fungi associated with brain abscesses at a tertiary care hospital in South India.

Methods and Material:

Eight years data was collected from the records of culture reports from 2007 to 2010 and 2013 to 2018. The corresponding clinical case records were retrieved for the assessment of risk factors. Risk factors of brain abscess development were assessed based on clinical cases records.

Results:

Data from 140 brain abscess cases obtained over a period of 8 years were analyzed. Out of the 140 samples, 66 (47.14%) were culture positive in which 33 (50%) had single aerobic/facultative anaerobic bacteria, 20 (30.3%) had mixture of more than one aerobic/facultative anaerobic bacteria, 12 (18.18%) had single obligate anaerobic bacteria and 1(1.5%) sample had Mycobacterium tuberculosis isolated. Among the total 92 isolates, Pseudomonas aeruginosa (21/92, 23%) and Staphylococcus aureus (20/92, 22%) predominated. Bacteroides fragilis group was the most common obligate anaerobe isolated. There were no fungal isolates. As there were various isolates isolated, hence there is heterogeneity of isolates detected Neuroanatomically, parietal lobe (45/140, 32%) was the most common location. Otogenic infection was the major risk factor for parietal and temporal lobe abscess (P value < .05).

Conclusions:

It has become essential for the microbiologists to be aware of unusual isolates from brain abscess and its complex nature. Obscurity and difficulty in their microbiological diagnosis calls for more such detailed studies.

Culture on Selective Media and Amplicon-Based Sequencing of 16S rRNA from Spontaneous Brain Abscess-the View from the Diagnostic Laboratory

Forty-one stored samples from cases of spontaneous brain abscess were investigated to gain insight into the natural history, causative agents, and relevant laboratory diagnostics of a rare infection. Samples from a larger collection were selected based on retrospective analysis of patient records. All samples were subjected to amplicon sequencing of 16S rRNA gene fragments. Supplementary culture on selected media was performed as suggested by bioinformatics analysis. For three cases, no microorganism was disclosed, while Toxoplasma gondii, Aspergillus fumigatus, and various bacteria were the cause of 1, 2, and 35 cases, respectively. Bacterial infections were monomicrobial in 20 cases and polymicrobial in 15; the microorganisms of the latter cases were restricted to residents of cavum oris. Amplicon sequencing did not further enhance the importance of the Streptococcus anginosus group, which was involved in 17 cases, and the single primer set used may be suboptimal for amplification of Actinomyces and Nocardia. But, amplicon-based sequencing unquestionably expanded the number of polybacterial infections, with focus on the Fusobacterium nucleatum group, Parvimonas, and Porphyromonas. Culture on selective media confirmed the presence of F. nucleatum group bacteria, which attained a prominence in spontaneous brain abscess similar to the S. anginosus group. Metagenomics is a powerful tool to disclose the spectrum of agents in polymicrobial infections, but a reliable cutoff value for substantial detection is complex. Commercial media for isolation of F. nucleatum group bacteria from mixed infections are available, and these pathogens should be carefully characterized. Isolation of Parvimonas and Porphyromonas in polymicrobial infections has not been resolved. IMPORTANCE Polymicrobial brain abscess is a challenge to the clinical microbiology laboratory due to the aggregative nature of the dental and oral microbiota. Because polymicrobial infections may escape detection by conventional culture methods, directed therapy toward a single detected bacterium is problematic. Amplicon-based sequencing provides important clues to these infections, but only cultured microorganisms can be fully characterized, subjected to antimicrobial susceptibility testing, and formally named. By use of specific selective culture plates, we successfully isolated bacteria of the Fusobacterium nucleatum group, and these bacteria rose to the same prominence as the widely recognized pathogen, the Streptococcus anginosus group. Named and unnamed members of the Fusobacterium nucleatum group must be further investigated to gain insight into a rare but grave disease.

Cerebral abscess with Streptococcus intermedius as a complication of pelvic inflammatory disease in the setting of intrauterine device use

A 43-year-old healthy female with no significant medical problems except for recently diagnosed pelvic inflammatory disease presented to our hospital with acute onset, severe head and neck pain. Brain imaging revealed a rim-enhancing lesion consistent with an abscess. The patient underwent successful surgical removal of the abscess and its capsule. Intraoperative cultures grew Streptococcus intermedius and she was discharged with a plan for four weeks of intravenous ceftriaxone.

Streptococcus intermedius causing cellulitis of the penile shaft complicated with abscess formation and rupture after dry humping sex

Penile cellulitis with abscess formation then rupture is an extremely rare presentation. This is a case report of a penile shaft abscess caused by Streptococcus intermedius after 'dry humping' sexual activities. A 34-year-old healthy man was presented with painful penile swelling for 3 weeks after initial 'dry humping' and later penovaginal intercourse. He was admitted to the hospital for intravenous antibiotics treatment, but a penile abscess was developed and ruptured within 24 hours. Urgent penile exploration revealed localised abscess and S. intermedius was isolated. The wound healed by secondary intention. However, his admission was complicated by acute kidney injury, probably due to vancomycin. Therefore, longer inpatient supportive care was required before discharge. Given this severe complication of primary penile cutaneous infection by S. intermedius, our case would raise awareness of this normal flora in abscess development at the male genital region, and the importance for the patient seeking prompt medical advice and physicians administrating appropriate antibiotics.