Anaerobic bacteriological profile of brain abscess in a tertiary care center in southern India

Augmented pathogen detection in brain abscess using metagenomic next-generation sequencing: a retrospective cohort study

Brain abscess is a severe infection characterized by the accumulation of pus within the brain parenchyma. Accurate identification of the causative pathogens is crucial for effective treatment and improved patient outcomes. This 10-year retrospective, single-center study aimed to compare the detection performance of conventional culture methods and metagenomic next-generation sequencing (mNGS) in brain abscess. We reviewed 612 patients diagnosed with brain abscess and identified 174 cases with confirmed etiology. The median age was 52 years, with 69.5% males. Culture tests predominately identified gram-positive bacteria, particularly Streptococcus spp. Gram-negative bacteria, including Klebsiella spp., were also detected. However, mNGS revealed a more diverse pathogen spectrum, focusing on anaerobes (e.g., Fusobacterium spp., Parvimonas spp., Porphyromonas spp., Prevotella spp., and Tannerella spp.). mNGS exhibited significantly higher overall pathogen-positive rates in pus samples (85.0% vs 50.0%, P = 0.0181) and CSF samples (84.2% vs 7.9%, P < 0.0001) compared to culture. Furthermore, the detection rates for anaerobes displayed a notable disparity, with mNGS yielding significantly higher positive detections in both pus samples (50.0% vs 10%, P = 0.0058) and CSF samples (18.4% vs 0%, P = 0.0115) when compared to culture methods. The assistance of mNGS in pathogen detection, particularly anaerobes in brain abscess, was evident in our findings. mNGS demonstrated the ability to identify rare and fastidious pathogens, even in culture-negative cases. These results emphasize the clinical value of mNGS as a supplement for brain abscess, enabling more comprehensive and accurate pathogen identification.IMPORTANCEThe accurate identification of pathogens causing brain abscess is crucial for effective treatment and improved patient outcomes. In this 10-year retrospective study, the detection performance of conventional culture methods and metagenomic next-generation sequencing (mNGS) was compared. The study analyzed 612 patients with brain abscess and confirmed etiology in 174 cases. The results showed that culture tests predominantly identified gram-positive bacteria, while mNGS unveiled a broader diverse pathogen spectrum, particularly anaerobes. The mNGS method exhibited significantly higher overall rates of pathogen positivity both in pus and cerebrospinal fluid (CSF) samples, surpassing the culture methods. Notably, mNGS detected a significantly higher number of anaerobes in both pus and CSF samples compared to culture methods. These findings underscore the clinical value of mNGS as a supplement for brain abscess diagnosis, enabling more comprehensive and accurate pathogen identification, particularly for rare and fastidious pathogens that evade detection by conventional culture methods.

Metagenomic next-generation sequencing identified a brain abscess caused by mixed oral anaerobe infection: A case report

Fusobacterium vincentii brain abscesses are relatively rare. Here, we report our treatment of an anaerobic brain abscess caused by a mixed infection of Parvimonas micra, Streptococcus constellatus, Fusobacterium vincentii, and Bacteroides heparinolyticus diagnosed by metagenomic next-generation sequencing (mNGS). This is the first reported case of Fusobacterium vincentii in a brain abscess. This case highlights the possibility that oral anaerobic microbes can cause a brain abscess and demonstrates that mNGS has the potential to be deployed to provide rapid infection diagnosis and rationalize antimicrobial therapy for brain abscesses.

Haemophilus aphrophilus and Eikenella corrodens Coinfection of Brain: An Unusual Case from China

Background

The HACEK group comprises Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae, are Gram-negative bacteria that are slow-growing and fastidious. These organisms are common causes of culture-negative endocarditis. However, brain abscesses caused by Haemophilus aphrophilus and E. corrodens have been rarely reported. The case we describe, which was promptly identified and successfully treated, will be meaningful for the diagnosis and treatment of such infectious diseases.

Case Presentation

Herein, we report a case of brain abscess in a young man who was infected with Haemophilus aphrophilus and E. corrodens. The patient was admitted to the hospital with sudden onset of vomiting, coma, and fever. Magnetic resonance imaging (MRI) of the brain and cerebrospinal fluid cell counts suggested cerebral abscess, he underwent drainage of the abscess and empirical antimicrobial therapy of meropenem (2 g every 8 hours) and linezolid (0.6 g every 12 hours) for more than 10 days without significant improvement. Metagenomic next-generation sequencing (mNGS) of drainage fluid and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) detection for isolated bacteria from samples suggested the presence of H. aphrophilus and E. corrodens. After 7 weeks of ceftriaxone (2 g every 12 hours) and meropenem (2 g every 8 hours) intravenously, the patient was discharged with a normal temperature and brain MRI showed improvement of the lesion.

Conclusion

Similar cases reported in previous studies were always associated with bacterial blood dissemination after dental surgery or myocarditis; however, the patient in our case had no any associated risk factors. As far as we know, this is the only case of central nervous system infection caused by H. aphrophilus and E. corrodens that has utilized combined mNGS and MALDI-TOF MS in the diagnosis.

Clinical analysis, diagnosis, and treatment strategies for otogenic brain abscesses

Objective: To explore the clinical features, diagnosis, and treatment strategies for otogenic brain abscesses (OBA). Methods: Clinical data from 10 patients with OBA were analyzed retrospectively. Clinical characteristics, diagnosis, and treatment experiences were summarized. Results: Two were first diagnosed in the Department of Otorhinolaryngology, 5 in Neurosurgery, and 3 in other departments. There were 6 cases of temporal lobe abscess and 4 cases of cerebellar abscesses. Five cases were accompanied by 1 or more intracranial complications. Headache is a common presentation in all cases. The main pathogenic bacteria were anaerobic bacteria. All patients had no previous ear or brain surgery history, and no history of traumatic brain injury, 7 received surgical treatment in the neurosurgery and/or otolaryngology department. Two patients died, the other 8 fully recovered and so were discharged. Conclusions: Diagnosis and treatment of OBA must involve multiple departments. Multidisciplinary consultation (MDT) is crucial to the success of the first OBA diagnosis. The diagnosis and treatment team develops personalized treatment plans by integrating MDT treatment opinions and combining the actual condition of patients, thereby making the diagnosis and treatment of OBA accurate and timely.

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.

Brain abscesses caused by anaerobic bacteria

OBJECTIVES

The objective of this study was to review the characteristics, causative bacteria, treatment and outcomes of brain abscesses due to anaerobes in our health setting.

METHODS

A retrospective analysis of all brain abscesses caused by anaerobic bacteria over the period 2005-2021 was performed.

RESULTS

Out of 300 brain abscesses identified during the study period, 31 were produced by anaerobic pathogens, either alone (monomicrobial infection) or together with aerobic and/or anaerobic bacteria (polymicrobial infection). The mean age of the 31 patients was 53 years, and 61.2% were male; 51.6% of infections were polymicrobial, with only four (12.9%) caused by anaerobic bacteria alone. Forty-three anaerobic bacteria were isolated: Cutibacterium acnes in thirteen (41.9%), Parvimonas micra in eight (25.8%), and Prevotella spp. in seven (22.5%). The most frequent etiologies were local neurosurgery (13/41.9%) and contiguous otogenic, oral, or sinus foci of infection (8/28.8%). Cancer was present in eight patients (28.8%), headaches in seventeen (54.8%), and fever in nine (28.8%). All patients received both surgery and antimicrobial therapy. The abscess was in the frontal region in 12 patients (38.7%) and in the parietal region in 11 (35.4%). A good outcome was obtained in all patients.

CONCLUSIONS

Anaerobes were isolated in 10.3% of patients with brain abscesses in our health setting, similar to other reports. C. acnes was the most frequently detected anaerobe, especially in neurosurgical patients.

Clinico-microbiological spectrum of anaerobic pyogenic infections in an Indian tertiary care teaching hospital: A two-year study

Introduction:

Anaerobes are important however the most neglected pathogens. Timely isolation of anaerobes can guide the clinician about the correct course of clinical treatment and thus reduce the mortality and also the problem of antimicrobial resistance.

Materials and Methods:

Tissue and/or pus aspirates were collected aseptically from infectious sites in the Robertson's cooked meat medium (RCM) and sent to anaerobic bacteriology laboratory for culture. Subcultures from RCM for each sample were done on neomycin blood agar and 5% sheep blood agar along with metronidazole disc (5μg). The plates were incubated in an anaerobic jar using GasPak for 72 hrs. The preliminary identification was performed by standard biochemical tests for both obligate and facultative anaerobic isolates. Speciations of obligate anaerobes were performed by Vitek 2 automated system.

Results:

Obligate anaerobes either single or polymicrobial were obtained in 38/216 (14.5 %) samples processed during the study period. Polymicrobial infections were reported in 21/216 (55.26%) samples and most commonly with obligate anaerobic gramnegative bacilli i.e. Prevotella-Porphyromonas and Bacteroides fragilis group. Most common monomicrobial anaerobic infections were observed with Veillonella spp. (n=4) and Porphyromonas spp. (n=4) followed by Bacteroides fragilis (n=3). Obligate anaerobes were predominantly isolated from skin and soft tissue infections (n=14) followed by surgical site infections (n=8).

Conclusion:

Although most of the infections are polymicrobial, a rise in the incidence of monomicrobial anaerobic infections has been noticed. Therefore, the performance of anaerobic cultures along with aerobic cultures is much needed for complete bacterial work-up of specimens from infectious sites and better patient management.