Incidence and mortality of brain abscess in Denmark: a nationwide population-based study

Influence of laboratory and radiographic parameters on the clinical presentation and outcome of surgically treated patients with primary brain abscesses

BACKGROUND

Brain abscesses can lead to severe clinical outcomes, including death. Most studies on brain abscesses focus either on patient cohorts including postsurgical/posttraumatic abscesses. This study aimed to assess the clinical presentation and postoperative outcomes in a homogeneous group of patients with primary, pyogenic brain abscesses who underwent surgical treatment.

METHODS

We retrospectively analyzed consecutive patients with pyogenic brain abscesses treated surgically at our center from 2008 to 2023. The primary endpoint was a modified Rankin Scale (mRS) score of ≥ 3 at discharge. Secondary endpoint was preoperative clinical status (mRS ≥ 3). We statistically correlated clinical, radiographic, and microbiological parameters with these endpoints.

RESULTS

A total of 60 patients (36.7% female) with a mean age of 48.5 ± 20.8 years were included in this study. Six patients (10.0%) had an unfavorable postoperative outcome, including two deaths (3.3%). Significant risk factors for poor outcomes included preoperative disturbance of consciousness (DOC) (p = 0.012) and elevated preoperative C-reactive protein (CRP) levels (p = 0.002). Larger abscess volume (37.4 mL vs. 16.1 mL, p = 0.065) and shorter mean distance to the ventricles (3 mm vs. 11.42 mm, p = 0.086) trended toward significance. The length of intensive care unit (ICU) stay was significantly longer for patients with unfavorable outcomes (p = 0.001). Upon admission, eighteen patients (30.0%) had an mRS score of ≥ 3. Elevated leukocyte count was identified as a significant risk factor for poor preoperative status (p = 0.007). Median clinical performance, measured by mRS, improved throughout the treatment course and during follow-up from 2 to 0.

CONCLUSIONS

Preoperative DOC and elevated CRP levels were identified as predictors of unfavorable outcomes. Elevated leukocyte count was a predictor for poor preoperative status.

Safe early switch to oral antibiotics in immunocompetent adults with intracranial bacterial suppurations: Retrospective of a 25-year experience in a tertiary care centre

BACKGROUND

Switching antibiotic therapy from intravenous to oral route (IVOS) has become the standard of care for many deep-seated infections. IVOS seems applicable to intracranial bacterial suppurations (ICBS) with a good safety profile but remains debated and has shown insufficient evidence to be recommended in the latest guidelines. We hypothesize that early IVOS is not associated with a poorer neurological prognosis.

MATERIAL

We conducted a single-center retrospective cohort study in a French tertiary hospital between October 1998 and June 2022. We included adult patients neuro-surgically treated for ICBS, who survived early hospitalization. The primary endpoint was to determine if outcome was associated with the duration of intravenous antibiotic therapy prior to IVOS. Secondary endpoints were total duration of antibiotic treatment, adverse effects and safety parameters.

RESULTS

We analysed data for 190 patients of whom 91 % underwent IVOS, after a median 9 days (IQR 5-15) of intravenous route. Patients with a favourable 6-month outcome (Glasgow Outcome Scale Extended ≥ 7) were more likely to receive shorter intravenous treatment (8 (IQR 5-15) versus 13 (IQR 5-23) days, p = 0.035). Patients having undergone early IVOS had fewer surgical revisions (p = 0.002). Treatment side effects did not differ between groups.

CONCLUSION

In patients with intracranial bacterial suppurations who have undergone surgery and are adequately monitored, switching from intravenous to oral antibiotics was not associated with a worse outcome, even when performed early. The absence of association between IVOS and death or poorer outcome requires confirmation in further studies.

Odontogenic brain abscess caused by Porphyromonas gingivalis and Streptococcus constellatus: a case report and review article

Background

Odontogenic brain abscess is a rare, but potentially fatal, central nervous system infection, with insidious onset and unclear etiology.

Methods

This case reports a 70-year-old male patient who developed an odontogenic brain abscess secondary to periodontal infection and underwent neurological surgery. Extract pus during surgery for the metagenomic next-generation sequencing (mNGS).

Results

The mNGS of pus samples obtained from brain abscess aspiration identified the periodontal pathogens Porphyromonas gingivalis and Streptococcus constellatus. Consequently, he was referred to the department of stomatology for further examination and treatment.

Conclusions

Our study found that major periodontal pathogens including P. gingivalis and S. constellatus were essential in the development of odontogenic brain abscesses; thus, timely intervention and preventive measures are important for treatment.

Dual RNA-seq reveals the complement protein C3-mediated host-pathogen interaction in the brain abscess caused by Staphylococcus aureus

This study aimed to elucidate the complement protein C3-mediated host-pathogen interaction in the brain abscess caused by Staphylococcus aureus infection. Dual RNA-seq was employed to analyze the transcriptomic differences between C3 deficiency and wild-type mice of S. aureus-induced brain abscess model, and then we investigated the potential regulatory pathways of S. aureus-host interaction mediated by C3 and S. aureus genes associated with the pathogenesis of brain abscess. Finally, C3 deficient-mice and hla mutants of S. aureus were used to verify the specific pathogen-host interaction. In the S. aureus-induced brain abscess mouse model, the transcriptomic analysis revealed significant changes in bacterial virulence factors, such as hemolysin. Based on these data, we predicted a regulatory network formed by genes like hrcA and dnaK, which represent a possible regulation mechanism of S. aureus responding to the host. Furthermore, we identified that hla was the C3 response gene in S. aureus. From the host perspective, we observed that the absence of C3 significantly impacted the host's inflammatory response, primarily by altering the gene expression of several key immune and inflammatory pathways. These findings suggest that C3 deficiency may impair the host's ability to recognize and respond to external pathogens. To the best of our knowledge, this study proposed that S. aureus may affect host immune response through C3, and C3 plays a critical role in regulating inflammation and immune signaling pathways in the brain abscess caused by S. aureus infection.IMPORTANCEIn this work, we employed immunofluorescence and Western blot analysis to reveal a significant upregulation of microglia-derived C3 in the brain abscess mice model caused by S. aureus infection. By integrating the individual RNA sequencing data of S. aureus and the dual RNA-seq data of S. aureus infection brain abscess mice model, the potential regulatory pathways between S. aureus and host were identified, and host C3 not only affects the immune response but also mediates the regulation network of S. aureus. This study provided the potential novel targets for therapeutic strategies in mitigating the effects of S. aureus infections and improving treatment outcomes.

Clinical characteristics, complications, and outcome of brain abscess treated by stereotactic aspiration: a retrospective analysis

BACKGROUND

The aim of this study was to investigate the clinical presentation, imaging features, and outcome of patients diagnosed with brain abscess and treated by stereotactic aspiration.

METHODS

We retrospectively analyzed the medical data of all consecutive patients diagnosed with brain abscess who underwent stereotactic aspiration in our department from 2015 to 2022. The demographic characteristics, clinical presentation, radiological data, microbial aetiology, and outcome were collected and analyzed using t-test or χ2 tests.

RESULTS

Overall, 120 patients were identified. The mean age was 49.7 years (range: 5-81); 59.2% were male. Seventy-nine patients (65.8%) had comorbidities, of which cardiovascular diseases was the most common. Most of the abscesses were solitary frontal or temporal lesions. A microbiological diagnosis was secured in 70 (58.3%) of cases, among which the majority were of the Streptococcus spp. Outcome was favorable in 107 (89.2%) of cases. The mortality rate during the initial hospital stay was 2.5%. A total of 10 individuals (8.3%) presented with preoperative delirium or coma, which was associated with an inferior clinical outcome compared to those who exhibited clear consciousness. (p = 0.01).

CONCLUSIONS

Stereotactic aspiration was a safe intervention with a low incidence of complications. The combination of stereotactic aspiration and antibiotic therapy was an effective treatment strategy for brain abscess. Patients who underwent stereotactic aspiration while in a state of disturbance of consciousness demonstrated a poorer outcome compared to those who were conscious.

CLINICAL TRIAL NUMBER

Not applicable.

Clinicodemographic and Radiological Features of Infective Ring-Enhancing Brain Lesions: A 4-Year Retrospective Study at a Tertiary Referral Center

Background

The diagnostic evaluation of ring-enhancing brain lesions (REBLs) is challenging, especially in immunocompromised patients. We conducted a retrospective study to describe the clinicodemographic and radiological features among patients presenting with REBLs to a tertiary referral center.

Methods

Radiological reports of all patients who underwent brain computed tomography or magnetic resonance (MR) imaging between 1 November 2013 and 31 October 2017 were filtered for terms indicative of REBLs. Infectious diseases physicians reviewed the medical records to confirm the diagnosis.

Results

Over the 4-year study period, there were 42 patients with infective REBLs and 249 with neoplastic REBLs. Pyogenic brain abscesses (PBAs) (20 of 42 [47.6%]) were the most common cause of infective REBLs, followed by tuberculous brain abscesses (TBAs) (9 of 42 [21.4%]) and Nocardia brain abscesses (NBAs) (6 of 42 [14.3%]). The patients were predominantly male, with a mean age of 55.2 years. Fewer than half were febrile at presentation. Cerebrospinal fluid investigations established the microbiological diagnosis in fewer than half of those who underwent lumbar puncture or extraventricular drain insertion. Conversely, brain biopsy yielded the microbiological diagnosis in almost all patients (16 of 17) who underwent the operation. Median white blood cell counts and C-reactive protein were higher in those with PBAs or NBAs than in those with TBAs. All with PBAs and NBAs who underwent MR imaging had diffusion-weighted imaging-hyperintense lesions, compared with only about half of those with TBAs.

Conclusions

Our study has revealed important distinguishing features between infective REBLs and neoplastic REBLs and between PBAs, TBAs, and NBAs.

Clinical features and outcome of brain abscess after introduction of CT and MRI: A meta-analysis

OBJECTIVE

To describe the clinical features and outcome of brain abscess since introduction of computerised tomography and magnetic resonance imaging.

METHODS

MEDLINE and Embase were searched using "brain abscess" or "cerebral abscess" from 1970 through 2023 and analyses restricted to study populations hospitalised after 1980. Single-variable meta-analyses were done using a random-effects model.

RESULTS

A total of 21,840 patients from 209 studies were included. The mean age was 34 years (95% confidence interval [CI] 30-38) and 11,817/17,406 (66%, 95% CI 64-67) were male. The aetiologies were consistent across time and continents with Streptococcus spp. 2064/6393 (32%, 95% CI 28-36), Staphylococcus spp. 1061/6393 (14%, 95% CI 12-16), and Gram-negative enteric bacteria 696/6393 (9%, 95% CI 7-11) as the most common. Predisposing conditions included otitis media/mastoiditis 1909/6433 (27%, 95% CI 22-33), immunocompromise 1022/4652 (19%, 95% CI 14-24), sinusitis 565/3725 (16%, 95% CI 12-20), and neurosurgery 745/4927 (16%, 95% CI 12-20). The case-fatality was 2444/18,991 (12%, 95% CI 11-14) and good recovery was found in 3419/5409 (63%, 95% CI 58-68).

CONCLUSIONS AND RELEVANCE

Brain abscess remains a disease predominantly occurring in men and is caused by contiguous or distant infections. Case fatality and outcome have not improved during recent decades.

Streptococcus intermedius: an underestimated pathogen in brain infection?

Streptococcus intermedius is an oral commensal organism belonging to the Streptococcus anginosus group (SAG). S. intermedius causes periodontitis as well as invasive, pyogenic infection of the central nervous system, pleural space or liver. Compared with other SAG organisms, S. intermedius has a higher mortality as well as a predilection for intracranial infection, suggesting it is likely to possess virulence factors that mediate specific interactions with the host resulting in bacteria reaching the brain. The mechanisms involved are not well described. Intracranial suppuration (ICS) due to S. intermedius infection can manifest as an abscess within the brain parenchyma, or a collection of pus (empyema) in the sub- or extra-dural space. These infections necessitate neurosurgery and prolonged antibiotic treatment and are associated with a considerable burden of morbidity and mortality. The incidence of ICS is increasing in several settings, with SAG species accounting for an increasing proportion of cases. There is a paucity of published literature regarding S. intermedius pathogenesis as well as few published genomes, hampering molecular epidemiological research. This perspective evaluates what is known about the clinical features and pathogenesis of ICS due to S. intermedius and explores hypothetical explanations why the incidence of these infections may be increasing.

Experimental animal models for brain abscess: a systematic review

BACKGROUND

Brain abscess (BA) is a rare, but severe infection and experimental BA animal models may prove crucial for advances in treatment. This review describes the development of experimental BA models and the clinical advances obtained from these, in a historical perspective.

MATERIAL AND METHODS

Experimental BA studies from inception until June 15, 2022, were included by searching the PubMed and Embase databases. Inclusion required the use of an experimental BA animal model. Non-bacterial BA models, in vitro studies, veterinarian case-reports, and articles written in non-English language were excluded. Bias was not systematically assessed, and the review was not registered at the PROSPERO.

RESULTS

79 studies were included. The majority of animal BA models have been based on small rodents using Staphylococcus aureus. The models have delineated the natural development of BA and provided detailed descriptions of the histopathological characteristics consisting of a necrotic centre surrounded by layers of inflammatory cells and fibroblasts encapsulated by a dense collagenous layer. Radiological studies of animal BA have been shown to correlate with the corresponding stages of human BA in both computed tomography and magnetic resonance imaging and may guide diagnosis as well as the timing of neurosurgical intervention. Moreover, pharmacokinetic studies of the intracavitary penetration of various antimicrobials have helped inform medical treatment of BA. Other studies have examined the diverse effects of corticosteroids including decreased cerebral oedema, intracranial pressure, and intracavitary drug concentration, whereas concerns on decreased or weakened capsule formation could not be confirmed. Finally, studies on the immunological response to BA have highlighted potential future immunomodulatory targets.

CONCLUSIONS

Animal models have been vital for improvements in the management of BA. Experimental BA models resembling human disease including polymicrobial infection by oral cavity flora in large animals are needed.

Profiles of primary brain abscesses and their impact on survival: An international ID-IRI study

OBJECTIVES

This study of 331 primary brain abscess (PBA) patients aimed to understand infecting agents, predisposing factors, and outcomes, with a focus on factors affecting mortality.

METHODS

Data were collected from 39 centers across 16 countries between January 2010 and December 2022, and clinical, radiological, and microbiological findings, along with their impact on mortality, were analyzed.

RESULTS

The patients had a mean ± SD age of 46.8 ± 16.3 years, with a male predominance of 71.6%. Common symptoms included headache (77.9%), fever (54.4%), and focal neurological deficits (53.5%). Gram-positive cocci were the predominant pathogens, with Viridans group streptococci identified as the most frequently isolated organisms. All patients received antimicrobial therapy and 71.6% underwent interventional therapies. The 42-day and 180-day survival rates were 91.9% and 86.1%, respectively. Significant predictors of 42-day mortality included intravenous drug addiction (HR: 6.02, 95% CI: 1.38-26.26), malignancy (HR: 3.61, 95% CI: 1.23-10.58), confusion (HR: 2.65, 95% CI: 1.19-5.88), and unidentified bacteria (HR: 4.68, 95% CI: 1.76-12.43). Significant predictors of 180-day mortality included malignancy (HR: 2.70, 95% CI: 1.07-6.81), confusion (HR: 2.14, 95% CI: 1.11-4.15), temporal lobe involvement (HR: 2.10, 95% CI: 1.08-4.08), and unidentified bacteria (HR: 3.02, 95% CI: 1.49-6.15).

CONCLUSION

The risk of death in PBA extends beyond the infection phase, with different factors influencing the 42-day and 180-day mortality rates. Intravenous drug addiction was associated with early mortality, while temporal lobe involvement was associated with late mortality.

Changes in the epidemiology of pediatric brain abscesses pre- and post-COVID-19 pandemic: a single-center study

BACKGROUND

An increased incidence of brain abscesses was observed post-COVID-19 pandemic. However, it remains unclear how the COVID-19 pandemic influenced the epidemiology of brain abscesses. This study aimed to investigate changes in the epidemiology of brain abscesses pre- and post-COVID-19 pandemic.

METHODS

A retrospective study of demographic, clinical, radiological, and laboratory characteristics of patients with brain abscesses in Children's Hospital of Soochow University from 2015-2023 was performed.

RESULTS

A total of 34 patients were admitted to the hospital during the study. The post-COVID-19 cohort had an average of 5.5 cases/year, which is a 129.2% increase compared to the pre-COVID-19 cohort's average of 2.4 cases/year. Additionally, the rates of fever upon admission (86.36% vs 50%, p = 0.04) and experiencing high-grade fever within 6 weeks before admission (40.91% vs 8.33%, p = 0.044) were significantly increased. A potential rise in the rate of intensive care unit admission was observed (36.36% vs 8.33%, p = 0.113). The average value of globulin in the post-COVID cohort was significantly higher compared to the pre-COVID cohort (31.60 ± 5.97 vs 25.50 ± 5.08, p = 0.009). Streptococcal infections were the predominant cause of brain abscesses in both cohorts (40% vs 43.75%, p = 0.57).

CONCLUSIONS

There was a significant increase in the number of brain abscess patients after the COVID-19 pandemic. This underscores the importance of children receiving the streptococcal vaccine.

Brain abscesses: the first report of disseminated Nocardia beijingensis infection in an immunocompetent individual in China

Nocardia is widely distributed in the natural environment and typically cause opportunistic infections. However, it is important to note that the pathogenicity of different Nocardia species may vary significantly. Here we reported the first case of brain abscess caused by Nocardia beijingensis (N. beijingensis) infection in China. A 70-year-old male immunocompetent individual came to our hospital for treatment due to headache. After examination, it was found that he had a brain abscess caused by N. beijingensis. By utilizing a combination of surgical intervention and antibiotic therapy, the patient ultimately achieved full recovery. In addition, we isolated this strain and displayed its ultrastructure through scanning electron microscopy. The phylogenetic tree was analyzed by 16 S rRNA sequence. A literature review of N. beijingensis infections in all immunocompetent and immunocompromised patients was presented. It highlighted that abscess formation appears to be a common manifestation of N. beijingensis infection, and N. beijingensis has become an emerging pathogen in immunocompetent individuals.

Fatigue and depression at 8 weeks and 1 year after bacterial brain abscess and their relationship with cognitive status

A bacterial brain abscess (BA) is a focal brain infection with largely unknown long-term implications. This prospective study assessed the frequency of fatigue and symptoms of depression at 8 weeks and 1 year after BA and examined the relationship between fatigue, depressive symptoms, and cognitive status. Twenty BA-patients (age 17-73; 45% female) were assessed for fatigue, depression, memory, and executive functions. Fatigue rates were 40-65% at 8 weeks and 25-33% at 1 year on various fatigue questionnaires. Patient Health Questionnaire indicated symptoms of depression in 10% at the 8-week follow-up only. Relevant comorbidities and vocational outcomes were not associated with fatigue or symptoms of depression. Mean fatigue scores improved significantly between the two-time points. Greater fatigue was related to subjective problems with working memory, inhibition, self-monitoring, and emotional control and worse objective verbal memory performance. Symptoms of depression were associated with one out of two fatigue measures. We conclude that fatigue is common in the first year after BA, and higher levels of fatigue are related to more cognitive problems. Symptoms of clinical depression were rare. These findings underscore fatigue as an important consequence of BA and emphasize the necessity for targeted rehabilitation interventions.

Cognitive and everyday functioning after bacterial brain abscess: a prospective study of functional recovery from 8 weeks to 1 year post-treatment

OBJECTIVE

A bacterial brain abscess may damage surrounding brain tissue by mass effect, inflammatory processes, and bacterial toxins. The aim of this study was to examine cognitive and functional outcomes at 8 weeks and 1 year following acute treatment.

METHODS

Prospective study of 20 patients with bacterial brain abscess (aged 17-73 years; 45% females) with neuropsychological assessment at 8 weeks and 1 year post-treatment. Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) and Patient Competence Rating Scale (PCRS) were used to assess everyday functioning and administered to patients and informants.

RESULTS

Cognitive impairment was found in 30% of patients at 8 weeks and 22% at 1 year. Significant improvements were seen on tests of perceptual reasoning, attention, verbal fluency, and motor abilities (p < 0.05). At 1 year, 45% had returned to full-time employment. Nevertheless, patients and their informants obtained scores within the normal range on measures of everyday functioning (PCRS and BRIEF-A) at 8 weeks and 1 year. No significant improvements on these measures emerged over time.

CONCLUSION

Residual long-term cognitive impairment and diminished work ability affected 22% and 45% of patients one year after BA. Persistent cognitive impairment emphasizes the importance of prompt acute treatment and cognitive rehabilitation.

Paraclostridium tenue Causing an Anaerobic Brain Abscess Identified by Whole-Metagenome Sequencing: A Case Report

When treating anaerobic brain abscesses, healthcare professionals often face the difficulty of identifying the causal pathogens, necessitating empiric therapies with uncertain efficacy. We present the case of a 57-year-old woman who was admitted to our hospital with a fever and headache. Brain magnetic resonance imaging revealed a hemorrhagic lesion with wall enhancement at the left hemisphere on contrast-enhanced T1-weighted imaging. Cerebrospinal fluid examination showed pleocytosis (23 cells/μL), an elevated protein level (125 mg/dL), and decreased glucose level (51 mg/dL; blood glucose was 128 mg/dL). Intracerebral hemorrhage accompanied by a brain abscess was clinically suspected. The patient received empirical treatment with intravenous meropenem and vancomycin for 2 weeks. However, conventional bacterial culture tests failed to identify the pathogen. We then performed shotgun sequencing and ribosomal multilocus sequence typing, which identified Paraclostridium tenue. Based on this finding, we de-escalated to benzylpenicillin potassium for 4 weeks, leading to a 2.5-year remission of the anaerobic brain abscess. Therefore, Paraclostridium can be a causative pathogen for brain abscesses. Furthermore, whole-metagenome sequencing is a promising method for detecting rare pathogens that are not identifiable by conventional bacterial culture tests. This approach enables more targeted treatment and contributes to achieving long-term remission in clinical settings.

Geriatric nutritional risk index has a prognostic value for recovery outcomes in elderly patients with brain abscess

Background

The Geriatric Nutritional Risk Index (GNRI) is a straightforward and objective tool for nutritional screening in older patients and has been demonstrated to possess prognostic predictive value in several diseases. Nonetheless, there is a lack of research on the nutritional risk associated with brain abscess in the older. This study aimed to evaluate the prevalence of nutritional risk among these patients by GNRI and to investigate its potential prognostic value for clinical outcomes.

Materials and methods

From August 2019 to April 2023, 100 older patients diagnosed with brain abscess were enrolled in this single-center prospective cohort study, which evaluated the prognostic value of the Geriatric Nutritional Risk Index (GNRI) in elderly brain abscess patients. Data collected included demographic, and clinical characteristics at admission and calculated the GNRI, and the Glasgow Outcome Scale (GOS) score 6 months post-discharge. A GOS score of 5 was considered indicative of a good recovery, whereas scores ranging from 1 to 4 were classified as poor recovery.

Results

The results revealed that 48% of older brain abscess patients were at risk of malnutrition according to the GNRI. These patients had significantly higher post-admission C-reactive protein (CRP) levels (p = 0.017), more comorbidities (p < 0.001), and higher age-adjusted Charlson Comorbidity Index (aCCI) scores (p < 0.001) compared to those without nutritional risk. Spearman correlation analysis showed that GNRI scores were negatively correlated with CRP levels, comorbidities, and aCCI scores, and positively correlated with Glasgow Outcome Scale (GOS) scores (Spearman's ρ = 0.624, p < 0.001). Multivariate logistic regression revealed that lower GNRI values were linked to reduced GOS levels (OR = 0.826, 95% CI: 0.775-0.880). ROC analysis determined a GNRI threshold of 97.50 for predicting poor recovery, with 90.57% sensitivity and 87.23% specificity.

Conclusion

The older brain abscess patients exhibited a high malnutrition risk. GNRI showed an important predictive value for recovery in older patients, which could be helpful in clinical intervention and rehabilitation.

Update and approach to patients with brain abscess

PURPOSE OF REVIEW

The epidemiology of brain abscess has changed in recent decades. Moreover, acute and long-term management remains challenging with high risks of mortality and neurological sequelae. This review describes recent advances in epidemiology, diagnosis, and treatment of brain abscess.

RECENT FINDINGS

The incidence of brain abscess is increasing, especially among elderly individuals. Important predisposing conditions include dental and ear-nose-throat infections, immuno-compromise, and previous neurosurgery. Molecular-based diagnostics have improved our understanding of the involved microorganisms and oral cavity bacteria including anaerobes are the predominant pathogens. The diagnosis relies upon a combination of magnetic resonance imaging, neurosurgical aspiration or excision, and careful microbiological examinations. Local source control by aspiration or excision of brain abscess combined with long-term antimicrobials are cornerstones of treatment. Long-term management remains important and should address neurological deficits including epilepsy, timely diagnosis and management of comorbidities, and potential affective disorders.

SUMMARY

A multidisciplinary approach to acute and long-term management of brain abscess remains crucial and source control of brain abscess by neurosurgery should be pursued whenever possible. Numerous aspects regarding diagnosis and treatment need clarification. Nonetheless, our understanding of this complicated infection is rapidly evolving.

Chronic suppurative otitis media

Chronic suppurative otitis media (CSOM) is a leading global cause of potentially preventable hearing loss in children and adults, associated with socioeconomic deprivation. There is an absence of consensus on the definition of CSOM, which complicates efforts for prevention, treatment, and monitoring. CSOM occurs when perforation of the tympanic membrane is associated with severe or persistent inflammation in the middle ear, leading to hearing loss and recurrent or persistent ear discharge (otorrhoea). Cholesteatoma, caused by the inward growth of the squamous epithelium of the tympanic membrane into the middle ear, can also occur. The optimal treatment of discharge in CSOM is topical antibiotics. In resource-limited settings where topical antibiotics might not be available, topical antiseptics are an alternative. For persistent disease, surgery to repair the tympanic membrane or remove cholesteatoma might offer long-term resolution of otorrhoea and potential improvement to hearing. Recent developments in self-fitted air-conduction and bone-conduction hearing aids offer promise as new options for rehabilitation.

ChatGPT fails challenging the recent ESCMID brain abscess guideline

BACKGROUND

With artificial intelligence (AI) on the rise, it remains unclear if AI is able to professionally evaluate medical research and give scientifically valid recommendations.

AIM

This study aimed to assess the accuracy of ChatGPT's responses to ten key questions on brain abscess diagnostics and treatment in comparison to the guideline recently published by the European Society for Clinical Microbiology and Infectious Diseases (ESCMID).

METHODS

All ten PECO (Population, Exposure, Comparator, Outcome) questions which had been developed during the guideline process were presented directly to ChatGPT. Next, ChatGPT was additionally fed with data from studies selected for each PECO question by the ESCMID committee. AI's responses were subsequently compared with the recommendations of the ESCMID guideline.

RESULTS

For 17 out of 20 challenges, ChatGPT was able to give recommendations on the management of patients with brain abscess, including grade of evidence and strength of recommendation. Without data prompting, 70% of questions were answered very similar to the guideline recommendation. In the answers that differed from the guideline recommendations, no patient hazard was present. Data input slightly improved the clarity of ChatGPT's recommendations, but, however, led to less correct answers including two recommendations that directly contradicted the guideline, being associated with the possibility of a hazard to the patient.

CONCLUSION

ChatGPT seems to be able to rapidly gather information on brain abscesses and give recommendations on key questions about their management in most cases. Nevertheless, single responses could possibly harm the patients. Thus, the expertise of an expert committee remains inevitable.

Brain Abscess Caused by Oral Cavity Bacteria: A Nationwide, Population-based Cohort Study

BACKGROUND

Oral cavity bacteria are the most frequent etiology of brain abscess. Yet, data on the clinical presentation and outcome are scarce.

METHODS

We performed a nationwide, population-based study comprising all adults (aged ≥18 years) with brain abscess due to oral cavity bacteria in Denmark from 2007 through 2020. Prognostic factors for unfavorable outcome (Glasgow outcome scale, 1-4) were examined using modified Poisson regression to compute adjusted relative risks (RRs) with 95% confidence intervals (CIs).

RESULTS

Among 287 identified patients, the median age was 58 years (interquartile range, 47-66), and 96 of 287 (33%) were female. Preexisting functional impairment was absent or mild in 253 of 280 (90%), and risk factors for brain abscess included immunocompromise in 95 of 287 (33%), dental infection in 68 of 287 (24%), and ear-nose-throat infection in 33 of 287 (12%). Overall, a neurological deficit was present in 246 of 276 (86%) and in combination with headache and fever in 64 of 287 (22%). Identified microorganisms were primarily the Streptococcus anginosus group, Fusobacterium, Actinomyces, and Aggregatibacter spp., and 117 of 287 (41%) were polymicrobial. Unfavorable outcome occurred in 92 of 246 (37%) at 6 months after discharge and was associated with antibiotics before neurosurgery (RR, 3.28; 95% CI, 1.53-7.04), rupture (RR, 1.89; 95% CI, 1.34-2.65), and immunocompromise (RR, 1.80; 95% CI, 1.29-2.51), but not with specific targeted antibiotic regimens. Identified dental infection was associated with favorable prognosis (RR, 0.58; 95% CI, .36-.93).

CONCLUSIONS

Brain abscess due to oral cavity bacteria often occurred in previously healthy individuals without predisposing dental infections. Important risk factors for unfavorable outcome were rupture and immunocompromise. However, outcome was not associated with specific antibiotic regimens supporting carbapenem-sparing strategies.

Brain abscess - A rare confounding factor for diagnosis of post-traumatic epilepsy after lateral fluid-percussion injury

OBJECTIVE

To assess the prevalence of brain abscesses as a confounding factor for the diagnosis of post-traumatic epilepsy (PTE) in a rat model of lateral fluid-percussion-induced (FPI) traumatic brain injury (TBI).

METHODS

This retrospective study included 583 rats from 3 study cohorts collected over 2009-2022 in a single laboratory. The rats had undergone sham-operation or TBI using lateral FPI. Rats were implanted with epidural and/or intracerebral electrodes for electroencephalogram recordings. Brains were processed for histology to screen for abscess(es). In abscess cases, (a) unfolded cortical maps were constructed to assess the cortical location and area of the abscess, (b) the abscess tissue was Gram stained to determine the presence of gram-positive and gram-negative bacteria, and (c) immunostaining was performed to detect infiltrating neutrophils, T-lymphocytes, and glial cells as tissue biomarkers of inflammation. In vivo and/or ex vivo magnetic resonance images available from a subcohort of animals were reviewed to evaluate the presence of abscesses. Plasma samples available from a subcohort of rats were used for enzyme-linked immunosorbent assays to determine the levels of lipopolysaccharide (LPS) as a circulating biomarker for gram-negative bacteria.

RESULTS

Brain abscesses were detected in 2.6% (15/583) of the rats (6 sham, 9 TBI). In histology, brain abscesses were characterized as vascularized encapsulated lesions filled with neutrophils and surrounded by microglia/macrophages and astrocytes. The abscesses were mainly located under the screw electrodes, support screws, or craniectomy. Epilepsy was diagnosed in 60% (9/15) of rats with an abscess (4 sham, 5 TBI). Of these, 67% (6/9) had seizure clusters. The average seizure frequency in abscess cases was 0.436 ± 0.281 seizures/d. Plasma LPS levels were comparable between rats with and without abscesses (p > 0.05).

SIGNIFICANCE

Although rare, a brain abscess is a potential confounding factor for epilepsy diagnosis in animal models of structural epilepsies following brain surgery and electrode implantation, particularly if seizures occur in sham-operated experimental controls and/or in clusters.

Clinical features, etiologies, and outcomes of central nervous system infections in intensive care: A multicentric retrospective study in a large Brazilian metropolitan area

PURPOSE

The goal of this study was to investigate severe central nervous system infections (CNSI) in adults admitted to the intensive care unit (ICU). We analyzed the clinical presentation, causes, and outcomes of these infections, while also identifying factors linked to higher in-hospital mortality rates.

MATERIALS AND METHODS

We conducted a retrospective multicenter study in Rio de Janeiro, Brazil, from 2012 to 2019. Using a prediction tool, we selected ICU patients suspected of having CNSI and reviewed their medical records. Multivariate analyses identified variables associated with in-hospital mortality.

RESULTS

In a cohort of 451 CNSI patients, 69 (15.3%) died after a median 11-day hospitalization (5-25 IQR). The distribution of cases was as follows: 29 (6.4%) had brain abscess, 161 (35.7%) had encephalitis, and 261 (57.8%) had meningitis. Characteristics: median age 41 years (27-53 IQR), 260 (58%) male, and 77 (17%) HIV positive. The independent mortality predictors for encephalitis were AIDS (OR = 4.3, p = 0.01), ECOG functional capacity limitation (OR = 4.0, p < 0.01), ICU admission from ward (OR = 4.0, p < 0.01), mechanical ventilation ≥10 days (OR = 6.1, p = 0.04), SAPS 3 ≥ 55 points (OR = 3.2, p = 0.02). Meningitis: Age > 60 years (OR = 234.2, p = 0.04), delay >3 days for treatment (OR = 2.9, p = 0.04), mechanical ventilation ≥10 days (OR = 254.3, p = 0.04), SOFA >3 points (OR = 2.7, p = 0.03). Brain abscess: No associated factors found in multivariate regression.

CONCLUSIONS

Patients' overall health, prompt treatment, infection severity, and prolonged respiratory support in the ICU all significantly affect in-hospital mortality rates. Additionally, the implementation of CNSI surveillance with the used prediction tool could enhance public health policies.

Brain abscess from oral microbiota approached by metagenomic next-generation sequencing: A case report and review of literature

BACKGROUND

Brain abscess is a serious and potentially fatal disease caused primarily by microbial infection. Although progress has been made in the diagnosis and treatment of brain abscesses, the diagnostic timeliness of pathogens needs to be improved.

CASE SUMMARY

We report the case of a 54-year-old male with a brain abscess caused by oral bacteria. The patient recovered well after receiving a combination of metagenomic next-generation sequencing (mNGS)-assisted guided medication and surgery.

CONCLUSION

Therefore, mNGS may be widely applied to identify the pathogenic microorganisms of brain abscesses and guide precision medicine.

European society of Clinical Microbiology and Infectious Diseases guidelines on diagnosis and treatment of brain abscess in children and adults

SCOPE

These European Society of Clinical Microbiology and Infectious Diseases guidelines are intended for clinicians involved in diagnosis and treatment of brain abscess in children and adults.

METHODS

Key questions were developed, and a systematic review was carried out of all studies published since 1 January 1996, using the search terms 'brain abscess' OR 'cerebral abscess' as Mesh terms or text in electronic databases of PubMed, Embase, and the Cochrane registry. The search was updated on 29 September 2022. Exclusion criteria were a sample size <10 patients or publication in non-English language. Extracted data was summarized as narrative reviews and tables. Meta-analysis was carried out using a random effects model and heterogeneity was examined by I2 tests as well as funnel and Galbraith plots. Risk of bias was assessed using Risk Of Bias in Non-randomised Studies - of Interventions (ROBINS-I) (observational studies) and Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) (diagnostic studies). The Grading of Recommendations Assessment, Development and Evaluation approach was applied to classify strength of recommendations (strong or conditional) and quality of evidence (high, moderate, low, or very low).

QUESTIONS ADDRESSED BY THE GUIDELINES AND RECOMMENDATIONS

Magnetic resonance imaging is recommended for diagnosis of brain abscess (strong and high). Antimicrobials may be withheld until aspiration or excision of brain abscess in patients without severe disease if neurosurgery can be carried out within reasonable time, preferably within 24 hours (conditional and low). Molecular-based diagnostics are recommended, if available, in patients with negative cultures (conditional and moderate). Aspiration or excision of brain abscess is recommended whenever feasible, except for cases with toxoplasmosis (strong and low). Recommended empirical antimicrobial treatment for community-acquired brain abscess in immuno-competent individuals is a 3rd-generation cephalosporin and metronidazole (strong and moderate) with the addition of trimethoprim-sulfamethoxazole and voriconazole in patients with severe immuno-compromise (conditional and low). Recommended empirical treatment of post-neurosurgical brain abscess is a carbapenem combined with vancomycin or linezolid (conditional and low). The recommended duration of antimicrobial treatment is 6-8 weeks (conditional and low). No recommendation is offered for early transition to oral antimicrobials because of a lack of data, and oral consolidation treatment after ≥6 weeks of intravenous antimicrobials is not routinely recommended (conditional and very low). Adjunctive glucocorticoid treatment is recommended for treatment of severe symptoms because of perifocal oedema or impending herniation (strong and low). Primary prophylaxis with antiepileptics is not recommended (conditional and very low). Research needs are addressed.

Early switch to oral antimicrobials in brain abscess: a narrative review

BACKGROUND

Early switch to oral antimicrobials has been suggested as a treatment strategy in patients with brain abscess, but the practice is controversial.

OBJECTIVES

This review aimed to summarize the background, current evidence, and future perspectives for early transition to oral antimicrobials in patients with brain abscess.

SOURCES

The review was based upon a previous systematic review carried out during the development of the ESCMID guidelines on diagnosis and treatment of brain abscess. The search used 'brain abscess' or 'cerebral abscess' as text or MESH terms in PubMed, EMBASE, and the Cochrane Library. Studies included in the review were required to be published in the English language within the last 25 years and to have a study population of ≥10 patients. Other studies known by the authors were also included.

CONTENT

In this review, the background for some experts to suggest early transition to oral antimicrobials in patients with mild and uncomplicated brain abscess was clarified. Next, results from observational studies were summarized and limitations discussed. Indirect support for early oral treatment of brain abscess was described with reference to other serious central nervous system infections and general pharmacological considerations. Finally, variations within and between countries in the use of early transition to oral antimicrobials in patients with brain abscess were highlighted.

IMPLICATIONS

Early transition to oral antimicrobials in patients with uncomplicated brain abscess may be of benefit for patients due to convenience of treatment and potential decreased risks associated with prolonged hospitalization and intravenous lines. The strategy may also confer a more rational allocation of healthcare resources and decrease expenses. However, the benefit/risk ratio for this strategy remains unresolved at present.

Multiple Abscesses in the Frontal, Temporal and Brainstem regions in a 4.5-year-Old Girl- An Illustrative Case Report

Background

Brainstem located abscesses are rare in the pediatric population. Diagnosis of brain abscess can be challenging as patients may present with nonspecific symptoms and the classical triad of headache, fever, and focal neurological deficit is not always present. Treatment can be conservative or a combination of surgical intervention with antimicrobial therapy.

Case Description

We present the first case of a 4.5-year-old girl with acute lymphoblastic leukemia that developed infective endocarditis (IE) and subsequently developed 3 suppurative collections (frontal, temporal, and brainstem). The patient had negative cerebrospinal, blood, and pus culture growth and subsequently underwent burr-hole drainage of the frontal and temporal abscesses with a 6-week course of intravenous antibiotic therapy with an uneventful postoperative course. At 1 year, the patient is left with minor right lower limb hemiplegia and no cognitive sequelae.

Conclusion

The decision to surgically intervene for brainstem abscesses is dependent on surgeon and patient factors including the presence of multiple collections, midline shift, the aim of source identification in sterile cultures, and the patient's neurological condition. Patients with hematological malignancies should be monitored closely for IE which is a risk factor for hematogenous spread of brainstem located abscesses.

Central nervous system abscesses and empyemas in England: epidemiological trends over five decades

OBJECTIVES

To report on population-based epidemiological trends in central nervous system (CNS) abscesses and empyemas in England over five decades.

METHODS

Trend analyses of age-sex-specific hospital admission and death rates using routinely collected English national hospital discharge records, mortality records, and annual population denominators from 1968 to 2019.

RESULTS

Hospital admission rates for CNS abscesses and empyemas were stable in England until the late 1980s. In the last two decades of the study period (1999-2019), first-time admissions increased from 1.24 per 100,000 population in 1999 (95% confidence interval [CI] 1.14-1.35) to 2.86 in 2019 (95% CI 2.72-3.01). Admission rates were highest among infants and older adults, and were higher for males than females. There were small but significant increases in annual mortality rates for CNS abscesses and empyemas over the last two decades of the study period after accounting for population ageing, but mortality remained low at around 0.1-0.2 per 100,000 population. Mortality increased with advancing age; deaths in childhood were extremely rare. Case fatality rates where a relevant diagnosis was recorded as either the underlying or contributing cause were 4.3% and 9.7% respectively.

CONCLUSIONS

The increase in CNS abscesses and empyemas in England might reflect improved case ascertainment, but the likelihood of a true rise in incidence should be considered.

Cerebral abscesses with odontogenic origin: a population-based cohort study

Objectives

Recent studies have indicated that cerebral abscess (CA) patients with odontogenic origin are on the rise. However, CA patients are often poorly characterized and with an unknown etiologic background. The purpose of this study is to identify and characterize CA patients that may have an odontogenic origin based on microbiologic, radiographic, and/or clinical findings.

Materials and methods

This is a population-based cohort study analyzing retrospective and prospective data from CA patients. Radiographic examinations of panoramic radiographs (PRs) or computed tomography (CT) scans were conducted. CA patients characterized with odontogenic origin required the fulfilment of the following criteria on admission: (1) Oral pathologic conditions were the only bacterial infections present, (2) oral microorganisms were isolated in the purulent exudate from the brain, and (3) radiographically and/or clinical recordings of oral pathologic conditions.

Results

A total of 44 patients could be included in this study of which 25 (57%) were characterized as having CA with a likely odontogenic origin. Type two diabetes (T2D) (p = 0.014) and microorganisms of the Streptococcus anginosus group (SAG) (p < 0.01) were overrepresented in patients with CAs of odontogenic origin.

Conclusions

Odontogenic infections may cause CAs to a greater extent than previously assumed. T2D was overrepresented among patients with odontogenic CA. When microorganisms of the SAG were isolated from the brain pus, CA patients had a predisposing odontogenic or sinus infection.

Clinical relevance

The identification of patients with a likely odontogenic CA will contribute to understanding the etiology of the infectious disease and highlighting the importance of preserving oral health.

Risk of Psychiatric Disorders, Use of Psychiatric Hospitals, and Receipt of Psychiatric Medication in Patients With Brain Abscess in Denmark

BACKGROUND

It is unknown whether patients diagnosed with brain abscess have an increased risk of psychiatric disorders.

METHODS

In this nationwide, population-based matched cohort study from Denmark, we compared the incidence of psychiatric disorders, use of psychiatric hospitals, and receipt of psychiatric medications between patients diagnosed with brain abscess and individuals from the general population, matched on date of birth, sex, and residential area.

RESULTS

We included 435 patients diagnosed with brain abscess and 3909 individuals in the comparison cohort: 61% were male and median age was 54 years. Patients diagnosed with brain abscess were more likely to suffer from comorbidity. The risk of a hospital diagnosis of psychiatric disorders was increased the first 5 years of observation. In the subpopulation, who had never been in contact with psychiatric hospitals or received psychiatric medication before study inclusion, the risk of developing psychiatric disorders was close to that of the background population, especially when we excluded dementia from this outcome. There was a substantial increase in the receipt of anxiolytics and antidepressants. The difference in the proportion of individuals who received anxiolytics and antidepressants increased from 4% (95% confidence interval [CI], 0%-7%) and 2% (95% CI, -1% to 5%) 2 years before study inclusion to 17% (95% CI, 12%-21%) and 11% (95% CI, 7%-16%) in the year after study inclusion.

CONCLUSIONS

Patients with brain abscess without prior psychiatric disorders or receipt of psychiatric medicine are not at increased risk psychiatric disorders diagnosed in psychiatric hospitals, but they have an increased receipt of psychiatric medication.

Invasive procedures and risk of brain abscess: a nationwide, population-based case-control study

OBJECTIVES

It is unknown whether invasive procedures are associated with brain abscess.

METHODS

Nationwide, population-based, matched case-control study of patients with culture verified brain abscess in Denmark from 1989 to 2016. Exposure was invasive procedures 0-6 months before study inclusion.

RESULTS

We identified 435 patients and 3909 controls. The level of comorbidity was higher among patients with brain abscess than among controls. A total of 48 cases (11%) had one or more invasive procedures 0-6 months before study inclusion (adjusted odds ratios (aOR) of 3.6 (95% confidence interval (CI): 2.5-5.1), a population attributable fractions of 8% (95% CI: 7-9)). In primary care, ear, nose and throat (ENT) procedures were associated with brain abscess (aOR of 4.0 (95% CI: 2.0-8.0)), but gastrointestinal endoscopies were not (aOR of 1.0 (95% CI: 0.3-3.2)). No bronchoscopies were performed in primary care. In the hospital-based setting, ENT procedures, bronchoscopies and gastrointestinal endoscopies were associated with an increased risk of brain abscess (aOR of 14.5 (95% CI: 4.8-43.8), 20.3 (95% CI: 3.8-110.1) and 3.4 (95% CI: 2.0-5.6), respectively).

CONCLUSIONS

The association between invasive procedures and brain abscess was more pronounced in the hospital-based setting than in primary care.

Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study

OBJECTIVE

Intracranial abscesses are relatively uncommon, but can result in significant mortality and morbidity. Whilst many potential causes of brain abscesses are recognised, in many cases the origin of infection remains clinically unidentified. Our objective was to investigate the role of bacteria found in the oral cavity in the development of brain abscesses.

METHODS

A retrospective analysis was performed using data from 87 patients admitted to a single UK neurosurgical unit with brain abscesses over a 16-year period. Using microbiological data obtained from abscess sampling and peripheral cultures, species of bacteria were categorised in patients where no primary source of infection was identified (NSI) for their brain abscess (n = 52), or where an infective source (ISI) was identified. The microbiological data was then screened to identify common oral bacteria in each group.

RESULTS

Brain abscesses from the ISI group (n = 35) demonstrated a significantly lower preponderance of oral bacteria (n = 8), than the NSI group (n = 29) (p < 0.05). Brain abscesses from the NSI group also had significantly higher counts of Streptococcus anginosus compared to ISI (p < 0.05), with brain abscesses being most common in the frontal and parietal lobes for both ISI and NSI.

CONCLUSIONS

These findings suggest that the oral cavity could be considered as a source of occult infection in cases of brain abscess where no clear cause has been identified. Future studies should include oral screening and microbiome analysis to better understand the mechanisms involved and develop approaches for prevention.

CLINICAL SIGNIFICANCE STATEMENT

Oral bacteria may be an under-recognised cause of brain abscesses. Careful review of oral health in brain abscess patients may help establish causation, particularly in patients with no cause for their abscess identified. Good levels of oral health may help prevent the development of brain abscesses in some individuals.

Surgical aspiration versus excision for intraparenchymal abscess: a systematic review and Meta-analysis

Brain abscesses are associated with considerable morbidity and mortality, requiring timely intervention to achieve favourable outcomes. With the advent of high-resolution computed tomography (CT) imaging, mortality following both aspiration and excision of brain abscesses has improved markedly. As a result, there has been a marked shift in neurosurgical practice with aspiration eclipsing excision as the favoured first-line modality for most abscesses. However, this trend lacks sufficient supporting evidence, and this systematic review and meta-analysis seeks to compare aspiration and excision in the treatment of brain abscess. Twenty-seven studies were included in the systematic review, and seven comparative papers in meta-analysis. Aspiration was the chosen technique for 67.5% of patients. Baseline characteristics from the studies included only in the systematic review demonstrated that abscesses treated by aspiration were typically larger and in a deeper location than those excised. In the meta-analysis, we initially found no significant difference in mortality, re-operation rate, or functional outcome between the two treatment modalities. However, sensitivity analysis revealed that excision results in lower re-operation rate. On average, the included studies were of poor quality with average Methodological Index for Non-Randomized Studies (MINORS) scores of 10.3/16 and 14.43/24 for non-comparative and comparative papers respectively. Our study demonstrates that excision may offer improved re-operation rate as compared to aspiration for those abscesses where there is no prior clinical indication for either modality. However, no differences were found with respect to mortality or functional outcome. Evidence from the literature was deemed low quality, emphasizing the need for further investigation in this field, specifically in the form of large, well-controlled, comparative trials.

Development of posttraumatic frontal brain abscess in association with an orbital roof fracture and odontogenic abscess: A case report

Background:

Brain abscess is a potentially fatal condition. Orbital fractures caused by penetrating injury may be associated with intracranial infection. Such complication associated with blunt trauma, orbital roof fractures, and odontogenic abscesses is exceedingly rare.

Case Description:

We report the case of a 40-year-old transgender female with a frontal abscess presenting several weeks following a motor vehicle crash from which she suffered multiple facial fractures and an odontogenic abscess. On computed tomography scan, the patient had multiple right-sided facial fractures, including a medial orbital wall fracture and a right sphenoid fracture extending into the superior orbital roof. There was hemorrhage notable in the right frontal lobe. Communication with the ethmoid sinuses likely provided a conduit for bacterial spread through the orbit and into the intracranial and subdural spaces.

Conclusion:

Skull base fractures that communicate with a sinus, whether it be frontal, ethmoid, or sphenoid may increase the risk of brain abscess, especially in patients who develop an odontogenic abscess. Surgical repair of the defect is essential, and treating patients prophylactically with antibiotics may be beneficial.

Rare brain and pulmonary abscesses caused by oral pathogens started with acute gastroenteritis diagnosed by metagenome next-generation sequencing: A case report and literature review

Odontogenic brain and pulmonary abscesses are extremely rare infectious diseases. It is mainly caused by the upward or downward transmission of local infection or blood-borne spread. In recent years, with the wide application of some novel testing methods in clinical practice, the diagnosis of unexplained infections such as odontogenic abscesses in different organs has gradually become clear. We report a case of a 21-year-old male who was healthy and had not received any oral treatment before onset. He started with acute gastroenteritis-related symptoms, then developed meningitis-related symptoms seven days later with septic shock. No obvious abscess lesions were found on head computed tomography (CT) at admission, and the etiology was not clear by routine examination, which was very easy to misdiagnose as a serious infection caused by intestinal pathogens. But odontogenic pathogens were found both in his blood and cerebrospinal fluid through metagenomic next-generation sequencing (mNGS) analysis. Subsequently, rechecked imaging examination displayed multiple brain and pulmonary abscesses. Finally, it was diagnosed as an odontogenic brain and pulmonary abscess. After an extremely lengthy anti-infection course (13 weeks of intravenous antibiotics plus 2 weeks of oral antibiotics) and surgery, the patient was improved and discharged from the hospital. From this case, we could see that the development of new diagnostic technologies such as mNGS plays an important role in the early and confirmed diagnosis of diseases previously difficult to diagnose such as odontogenic polymicrobial infections and ultimately helps to improve the prognosis of these patients.

Aspiration Surgery with Appropriate Antibiotic Treatment Yields Favorable Outcomes for Bacterial Brain Abscess

BACKGROUND

Even in the era of advanced medical treatment, brain abscess still has a high mortality rate. At our institution, brain abscess has been treated mainly using stereotactic or echo-guided aspiration followed by relatively long-term antibiotic treatment, achieving favorable outcomes. To evaluate the efficacy of our strategy involving less-invasive aspiration surgery and long-term selective antibiotic administration for brain abscess, a single-institution series of cases was investigated.

METHODS

We retrospectively reviewed and analyzed the medical records of 25 cases of brain abscess treated at Saitama Medical University Hospital between 2008 and 2021. The patients comprised 16 men and 9 women aged between 39 and 85 years (median 62 years). Neurosurgical intervention was performed for 23 (92.0%) of the patients and the remaining 2 received antibiotics alone.

RESULTS

Among the neurosurgery patients, 22 (95.7%) underwent echo-guided or stereotactic aspiration, and only 1 underwent craniotomy. Anaerobic bacteria were detected in 11 patients. In the surgical and conservative groups, the median duration of antibiotic treatment was 16 weeks and 23 weeks, respectively. Since 2014 when metronidazole first became available, it has replaced meropenem to cover anaerobic bacteria. The overall mortality rate was 4.0% and a favorable outcome (Glasgow Outcome Scale 4 or 5) was achieved in 76% of the patients. There was no surgical mortality or morbidity.

CONCLUSIONS

Most patients underwent aspiration surgery and achieved favorable outcomes. Along with antibiotic treatment for a sufficiently long period to cover anaerobes, this approach can be expected to yield good results.

Plasma Microbial Cell-Free DNA (CF-DNA) Next-Generation Sequencing in Diagnosing Intracranial Abscesses: Pathophysiology and a Scoping Review of the Literature

Plasma microbial cell-free DNA (cf-DNA) from next-generation sequencing (NGS) provides improved sensitivity and specificity compared to standard microbial blood cultures. cf-DNA sequencing also has an improved turnaround time (TAT) and allows quicker commencement of antibiotics in life-threatening infections such as a brain abscess. Brain abscesses carry significant morbidity and mortality. Empiric treatment and management are critical in improving functional neurological outcomes. Reported here is the case of a severe central nervous system (CNS) infection with multiple ring-enhancing lesions seen throughout the cerebrum on magnetic resonance imaging (MRI). Standard microbial blood cultures were inconclusive and definitive identification of the pathogen was achieved through microbial cf-DNA NGS.  Brain abscesses develop in four distinct phases: early cerebritis, late cerebritis, early capsule formation, and late capsule formation. The pathogenesis of cerebral abscess involves direct parenchymal inflammation of the pathogen, the recruitment of inflammatory CNS cell types (microglia, inflammatory astrocytes, etc), and the chemotaxis of immune cells. cf-DNA is released into the bloodstream in response to pathogen opsonization and immune-mediated cell death. A scoping literature review includes cases of intracranial abscesses diagnosed via cf-DNA NGS.

Odontogenic brain abscess due to Anaerococcus prevotii infections: A case report and review article

BACKGROUND

Odontogenic brain abscess is a rare case primarily caused by normal flora such as Anaerococcus prevotii.

CASE PRESENTATION

A 60-years-old Indonesian female complained of severe left side headaches, hearing loss, a decrease of consciousness, several episodes of nausea and vomiting, and hemiparesis dextra for 5 days. Three months previously, she performed dental operative procedures on the left side of the first and second lower molar and debridement of phlegmon on the left side of the mouth. Head CT scan suggests multiple brain abscesses or high-grade glioma, non-communicating hydrocephalus and suggestive mastoiditis. The patient underwent excision surgery and abscess culture, which resulted in Anaerococcus prevotii. The patient received a metronidazole antibiotic, and on the seventh day, his condition improved.

DISCUSSION

Identifying bacterial infection in the brain abscess is crucial for effective treatment. Abscess removal in the brain and antibiotics are treatments for brain abscesses.

CONCLUSION

Odontogenic brain abscess caused by Anaerococcus prevotii infection effectiveness with surgical excision and antibiotics.

Brain Abscess and Risk of Cancer: A Nationwide Population-Based Cohort Study

Background and objectives:

Underlying occult cancer could potentially explain some of the observed increased long-term mortality among brain abscess patients.

Methods:

Nationwide, population-based healthcare registries were used to examine long-term risks of cancer in brain abscess patients from 1982 through 2016 compared with a population comparison cohort individually matched (10:1) on age, sex, and residence. Cumulative incidences and adjusted cause-specific hazard rate ratios (HRR) with 95% confidence intervals (CIs) for cancer were computed. Potential confounding by family-related factors was explored by comparing cumulative incidences of cancer among siblings of both groups.

Results:

Among 1,384 brain abscess patients (37% female, median age 50 years, IQR 33-63), cancer was observed in 218 (16%) compared with 1,657/13,838 (12%) in the comparison cohort yielding an adj. HRR of 2.09 (95% CI 1.79-2.45). Median time to diagnosis of cancer was 1.8 years (IQR 0.02-9.1) in brain abscess patients and 8.6 years (IQR 3.9-15.9) in comparison cohort. Among brain abscess patients, central nervous system and eye cancer was diagnosed in 59 (4.3%), of which 47/59 (80%) occurred within 90 days of the admission date, metastasizing cancer in 54 (3.9%), respiratory tract cancer in 48 (3.5%), and gastro-intestinal cancer in 36 (2.6%). Results remained consistent in almost all subgroups and in sensitivity analyses. Accounting for competing risk of death, the 1-, 5-, 10-, and 35-year cumulative incidence of cancer was 7% (95% CI 6-8), 11% (95% CI 9-12), 13% (95% CI 11-15), and 24% (95% CI 20-27) in brain abscess patients compared with 0.7% (95% CI 0.6-0.9), 4% (95% CI 4-5), 8% (95% CI 8-9), and 25% (95% CI 23-27) in the comparison cohort. The cumulative incidences of cancer among siblings of brain abscess patients was 10% and 12% among siblings of the comparison cohort.

Discussion:

Brain abscess was associated with substantially increased risk of cancer during the first ten years after diagnosis.

Brain abscess in immunocompetent patients: recent findings

PURPOSE OF REVIEW

We conducted a systematic review of the literature to update findings on the epidemiology and the management of cerebral abscesses in immunocompetent patients.

RECENT FINDINGS

Observational studies suggest that the overall prognosis has improved over the last decades but mortality rates remain high. Several parameters may contribute to a better prognosis, including the identification of common risk factors for brain abscess, the systematic use of brain MRI at diagnosis, the implementation of appropriate neurosurgical and microbiological techniques for diagnosis, the optimization of the antibacterial treatment based on epidemiology and pharmacokinetic/pharmacodynamic studies, and a long-term follow-up for detection of secondary complications. Outcome research on brain abscess is mainly based on observational studies. Randomized controlled trials have yet to be performed to identify clinically relevant interventions associated with improved patient-centered outcomes.

SUMMARY

Our review highlights the importance of a multidisciplinary approach to optimize brain abscess management both at the acute phase and in the long-term. Randomized controlled studies are urgently needed to identify interventions associated with improved outcomes.

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.

Dentist's visits and risk of brain abscess: a nationwide, population-based case control study

BACKGROUND

Brain abscesses are frequently caused by oral cavity bacteria, but whether dental status and invasive dental procedures are important risk factors is unknown.

METHODS

A nationwide, population-based, case-control study examined the association between dentist's visits and invasive dental procedures and risk of brain abscess caused by oral cavity bacteria from 1989-2016. Date of brain abscess diagnosis was considered the index date. Using risk-set sampling, 10 population controls per case were individually matched by age, sex, and residential area. Conditional logistic regression was used to compute odds ratios (OR) with 95% confidence intervals (CIs), adjusted for comorbidity (aOR).

RESULTS

We identified 362 patients with culture-proven brain abscess caused by oral cavity bacteria. The median age was 53 years (IQR 39 - 65) and 220/362 (61%) were male. Invasive dental procedures within six months before the index date was observed in 21/362 (6%) brain abscess patients and 179/3257 (5%) population controls yielding an aOR of 1.07 (95% CI 0.67-1.70). A total of 213/362 (59%) brain abscess patients had visited their dentist within one year before the index date compared with 1944/3257 (60%) of population controls corresponding to an aOR of 0.99 (95% CI 0.77-1.26). Using no dentist's visits as reference, we observed aOR's of 0.95 (95% CI 0.64-1.40) for 1-2 visits within three years of the index date and 1.01 (95% CI 0.76-1.35) for 3 or more visits.

CONCLUSIONS

Recent invasive dental procedures and number of dentist's visits were not associated with culture verified brain abscess caused by oral cavity bacteria.

Rapid Diagnosis of Central Nervous System Scedosporiosis by Specific Quantitative Polymerase Chain Reaction Applied to Formalin-Fixed, Paraffin-Embedded Tissue

Scedosporium (S.) apiospermum is a typical mold causing cerebral abscesses, often after near-drowning. Infections are associated with high morbidity and mortality due to diagnostic challenges including the need for prolonged incubation of cultures. In addition, histopathological differentiation from other filamentous fungi, including Aspergillus fumigatus, may not be possible, excluding early specific diagnosis and targeted therapy. Polymerase chain reaction (PCR) on tissue samples can rapidly identify fungi, leading to an earlier adequate treatment. Due to an extensive spectrum of causative fungi, broad-range PCRs with amplicon sequencing have been endorsed as the best DNA amplification strategy. We herein describe a case with brain abscesses due to S. apiospermum in a 66-year-old immunocompromised female patient. While broad-range PCR failed to identify a fungal pathogen from a cerebral biopsy demonstrating hyaline mold hyphae, specific quantitative PCR (qPCR) identified Scedosporium and ruled out Aspergillus, the most prevalent agent of central nervous system mold infection. A panel of specific qPCR assays, guided by the morphology of fungal elements in tissue or as a multiplex assay, may be a successful molecular approach to identify fungal agents of brain abscesses. This also applies in the presence of negative broad-range fungal PCR, therefore providing diagnostic and therapeutic potential for early specific management and improvement of patient clinical outcome.

Pearls & Oy-sters: Cerebral Abscess Secondary to Pulmonary Arteriovenous Malformation in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant condition which is linked to a myriad of neurological complications arising from vascular malformations of the brain, spinal cord, and lungs. Our case describes a previously healthy 3-year-old male who presented to hospital with fever of unknown origin and was found to have a brain abscess stemming from a pulmonary arteriovenous malformation (PAVM). This etiology was identified after a period of diagnostic delay; the medical team was suspicious for a proximal embolic source due to the presence of multiple tiny infarcts seen on MRI brain, but transthoracic echocardiogram and head and neck angiogram were unremarkable. Fortunately, an enhanced CT chest was performed, identifying a moderately-sized PAVM. PAVMs are associated with intracranial abscesses due to shunting and loss of the normal filtering effects of the lung capillary bed. Impaired pulmonary filtration can permit paradoxical thromboemboli and septic microemboli to enter systemic circulation, predisposing patients with PAVMs to cerebral abscess and ischemic stroke. Screening for PAVMs with contrast enhanced echocardiogram or enhanced CT chest may be considered in patients with cryptogenic brain abscess or recurrent embolic stroke of unknown origin. PAVMs are often associated with hereditary hemorrhagic telangiectasia (HHT). As many features of HHT have delayed clinical manifestation, genetic testing for HHT should be considered in patients with PAVM, even in the absence of other clinical features. In our case, genetic testing returned positive, confirming a new diagnosis of HHT type 1.

Partial oral antibiotic treatment for bacterial brain abscess: an open-label randomized non-inferiority trial (ORAL)

Background

The advised standard treatment for bacterial brain abscess following surgery is 6 to 8 weeks of intravenous (IV) antibiotic treatment, but an early switch to oral antibiotic treatment has been suggested to be equally effective.

Methods

This investigator-initiated, international, multi-center, parallel group, open-label, randomized (1:1 allocation) controlled trial will examine if oral treatment after 2 weeks of IV antibiotic therapy is non-inferior to standard 6–8 weeks of IV antibiotics for bacterial brain abscess in adults (≥ 18 years of age). The study will be conducted at hospitals across Denmark, the Netherlands, France, Australia, and Sweden. Exclusion criteria are severe immunocompromise or impaired gastro-intestinal absorption, pregnancy, device-related brain abscesses, and brain abscess caused by nocardia, tuberculosis, or Pseudomonas spp. The primary objective is a composite endpoint at 6 months after randomization consisting of all-cause mortality, intraventricular rupture of brain abscess, unplanned re-aspiration or excision of brain abscess, relapse, or recurrence. The primary endpoint will be adjudicated by an independent blinded endpoint committee. Secondary outcomes include extended Glasgow Outcome Scale scores and all-cause mortality at end of treatment as well as 3, 6, and 12 months since randomization, completion of assigned treatment, IV catheter associated complications, durations of admission and antibiotic treatment, severe adverse events, quality of life scores, and cognitive evaluations. The planned sample size is 450 patients for a one-sided alpha of 0.025 and a power of 90% to exclude a difference in favor of standard treatment of more than 10%. Date of initiation of first study center was November 3, 2020, with active recruitment for 3 years and follow-up for 1 year of all patients.

Discussion

The results of this study may guide future recommendations for treatment of bacterial brain abscess. If early transition to oral antibiotics proves non-inferior to standard IV treatment, this will provide considerable health and costs benefits.

Trial registration

ClinicalTrials.gov NCT04140903, first registered 28.10.2019. EudraCT number: 2019-002845-39, first registered 03.07.2019

Analysis of 93 Brain Abscess Cases to Review the Effect of Intervention to Determine the Feasibility of the Management Protocol: A Tertiary Care Perspective

Context

Brain abscess is a suppurative process within the brain parenchyma, which remains a challenge for clinicians. Surgical excision or aspiration combined with prolonged antibiotics (usually 4-8 weeks) or only conservative management remains the treatment of choice.

Aims

The purpose of this study is to analyze the epidemiology of brain abscess and to determine the potential factors leading to better outcomes.

Settings and Design

This was a retrospective analysis of 93 patients undergoing various treatment options for brain abscess in a tertiary care center.

Materials and Methods

Their preoperative status, etiology, and microbiological and clinical outcomes were analyzed.

Statistical Analysis Used

Statistical analysis was done by Chi-square, one-way analysis of variance, and post hoc Newman-Keuls multiple comparison test wherever applicable using SPSS software.

Results

Among 93 brain abscess cases, only 21 cases had a diameter <2.5 cm. Among them, conservative treatment was done for 38% of patients (8/21), aspiration for 47.6% (10/21) of patients, and excision for only 3 (14.2%) of cases. About 37.5% (3/8) persons among these conservatively managed patients had recurrence. None of the patients of <2.5 cm abscess having surgical management had recurrence or any new neurological deficits postsurgery during the 6-month follow-up.

Conclusions

There was a significantly high recurrence among the nonsurgically treated patients with lesions <2.5 cm and there was no recurrence or neurological deficit after aspiration among these patients. Probably, aspiration has better results among these patients contrary to previous recommendations of antibiotic therapy alone.

Diagnostics with clinical microbiome-based identification of microorganisms in patients with brain abscesses-a prospective cohort study

Brain abscesses are often polymicrobial and of unclear primary origin. Here, we compare the use of next-generation sequencing (NGS) technology with classical microbiological diagnostics for identification of clinically relevant microorganisms and describe the microbiome profiling with respect to the primary source of brain abscess. Thirty-six samples from 36 patients, with primary brain abscesses, were subjected to both culture- and 16S/18S rRNA Sanger sequencing-based diagnostics ("standard methods") and compared to a 16S/18S amplicon-based NGS, which were also subjected to a microbiome diversity analyses. Forty-seven species were identified with "standard methods" compared to 96 species with NGS, both confirming and adding to the number of species identified (p < 0.05). The variation of the brain abscess microbiome diversity was not continuous but could be stratified comparing the presumable origin of infection ("dental," "sinus," "disseminated," or "unknown"). Alpha diversity did not differ (p > 0.05) between groups while beta diversity differed significantly (p = 0.003) comparing disseminated vs the other presumable origin of infection. Interesting, clustering was also detected between "dental" and "sinusitis," although not significantly (p = 0.07). Microbiome-based diagnostics can increase sensitivity without losing specificity. The bacterial beta diversity differed between the presumably origin of the brain abscess and might help to clarify the primary source of infection.

Risk factors for unfavorable clinical outcomes in patients with brain abscess in South Korea

Background

Brain abscess can be life-threatening and manifest various neurological findings, although the mortality rate has decreased recently. We investigated the risk factors for unfavorable outcomes of patients with brain abscess.

Methods

A retrospective cohort study examined patients with brain abscess seen from May 2005 to December 2018 in a tertiary care hospital in Seoul, South Korea. We reviewed the medical records for clinical findings, therapeutic modalities, and prognostic factors of brain abscess. Unfavorable clinical outcomes were defined as death, moderate to severe disability with neurological deficits, or vegetative state at 1 year or at the time of discharge from outpatient follow-up.

Results

The study enrolled 135 patients: 65.2% were males; the mean age was 56 years. 35.6% had unfavorable outcomes. In multivariate analysis, higher Sequential Organ Failure Assessment (SOFA) (p < 0.001), pre-existing hemiplegia (p = 0.049), and higher Charlson comorbidity index (CCI) (p = 0.028) were independently associated with unfavorable outcomes.

Conclusions

Higher SOFA, pre-existing hemiplegia and higher Charlson comorbidity index were significant risk factors for unfavorable clinical outcomes in patients with brain abscess.

Persistent brainstem abscess requiring repeat microsurgical drainage: case report

In this paper, we present a patient who was treated for a pontine abscess at our institution. This patient underwent sub-occipital craniotomy for microscopic abscess drainage after which cultures grew Streptococcus intermedius. She was treated with antibiotics but failed to show clinical improvement and was taken back to the operating room for repeat abscess drainage. Clinical improvement was seen after the second operation. This case report describes open surgical technique as a safe and effective way of treating brainstem abscess.