Bacteroides fragilis spondylitis after suspected oral ulcer: a clinical case and comprehensive literature review.

This paper reports a case of Bacteroides fragilis induced spondylitis. Diagnosis was confirmed through blood culture and metagenomic sequencing of pus for pathogen detection. Due to persistent lumbar pain, surgical intervention became imperative, resulting in favorable postoperative outcomes. A detailed patient history revealed a severe episode of oral ulceration two weeks before symptom onset, although a direct link to the infection remained elusive. Leveraging insights from this case, we conducted a comprehensive literature review on B. fragilis spondylitis, elucidating clinical manifestations, diagnostic methodologies, and therapeutic strategies.

Clinical significance of Bacteroides fragilis as a potential prognostic factor in colorectal cancer.

INTRODUCTION: Bacteroides fragilis (B. fragilis) is considered to act in an anti-inflammatory manner on the intestinal tract. On the contrary, enterotoxigenic B. fragilis (ETBF), a subtype of B. fragilis, produces an enterotoxin (BFT; B. fragilis toxin), leading to asymptomatic chronic infections and colonic tumor formation. However, the impact of B. fragilis and ETBF on the clinical outcome of colorectal cancer (CRC) remains unclear. We aim to assess whether their presence affects the outcome in patients with CRC after curative resection. METHODS: We obtained 197 pairs of matched formalin-fixed paraffin-embedded samples from cancerous and adjacent non-cancerous tissues of patients with pathological stage (pstage) II and III CRC after curative resection. The presence of B. fragilis and ETBF were estimated using real-time polymerase chain reaction, and recurrence-free survival (RFS) and overall survival (OS) of the patients were analyzed. RESULTS: 16S rRNA for B. fragilis and bft DNA were detected in 120 (60.9%) and 12 (6.1%) of the 197 patients, respectively. B. fragilis-positive patients had better RFS than B. fragilis-negative patients, although that was not statistically significant. In subgroup analysis, better outcomes on RFS were observed in the presence of B. fragilis in pstage II and left-sided CRC. The association of B. fragilis positivity on OS was accentuated in the depth of T4 subgroup. No significant differences were observed in RFS and OS between ETBF and non-toxigenic B. fragilis. CONCLUSIONS: Our findings suggest that the presence of B. fragilis is associated with better outcomes in patients with pstage II and III CRC after curative resection.

Intra-spinal abscess due to Bacteroides fragilis and Klebsiella pneumoniae co-infection in a child with spinal dysraphism.

Bacteroides fragilis (B. fragilis) is an uncommon cause of spinal abscess. We present a case of an 18-month-old child, with spinal dysraphism-Spina bifida occulta, who developed intra-spinal abscess infection with B. fragilis and Klebsiella pneumoniae. Magnetic resonance imaging (MRI) of the brain and spine showed multiple abscesses extending through the presacral fistula into the spinal cord. Patient was surgically treated along with administration of antimicrobial agents (ceftriaxone and metronidazole), resulting in an excellent clinical outcome.

Identification of enterotoxigenic Bacteroides fragilis in patients with diarrhea: A study targeting 16S rRNA, gyrB and nanH genes.

OBJECTIVES: We aimed to identify the enterotoxigenic Bacteroides fragilis (ETBF) and bft subtypes among patients with diarrhea. In addition, we assessed whether DNA gyrase subunit B (gyrB) and neuraminidase (nanH) genes are useful determinants for identification of B. fragilis compared to 16S rRNA sequencing as a reference method. METHODS: The 530 fecal specimens were cultured on BBE agar. The colonies which supposed to be a member of B. fragilis group were subjected to 16S rRNA gene sequencing and PCR assays targeting the Bacteroides fragilis group (BFG), gyrB and nanH. The B. fragilis toxin (bft) gene and its subtype was detected by PCR. The specificity of PCR assays was calculated considering the 16S rRNA gene sequencing as the reference method. RESULTS: A total of 111 Gram-negative anaerobic coccobacilli were isolated from 530 fecal specimens using BBE agar. Of the 111 isolates, 100 (90.09%) were assumed to be a member of Bacteroides fragilis group as they yielded an amplicon through PCR using the group-specific primers (Bfra-F/g-Bfra-R). However, only 28 isolates out of 100 were definitively identified as species of Bacteroides using16S rRNA gene sequencing; of which 15 isolates were B. fragilis and the remaining 13 isolates were identified as B. thetaiotaomicron (n = 6), Parabacteroides distasonis (n = 3), B. vulgatus (Phocaeicola vulgatus) (n = 1), B. ovatus (n = 1), B. congonensis (n = 1) and B. nordii (n = 1). Among the 15 isolates of B. fragilis, 4 were found to be ETBF. Compared to the reference method, the specificity and accuracy of the PCR targeting gyrB gene (64.7% and 65%) was higher than of nanH (36.4% and 46%, respectively. CONCLUSIONS: This study demonstrated that more than one-fourth of B. fragilis isolates harbored bft gene and less than 1% of patients with diarrhea harbored ETBF. The slight agreement between the PCR assays -already used for identification of B. fragilis which targeting gyrB or nanH - and 16S rRNA gene sequencing as the reference method was noted.

Bacteroides fragilis vertebral osteomyelitis: A rare clinical entity.

Acute pyogenic vertebral osteomyelitis is mainly attributed to haematogenous spread of aerobic bacteria, while anaerobic osteomyelitis results from contiguous spread of polymicrobial infections through breaks in the gut mucosal barrier and involves the vertebral bodies in only about 2%-5%. Herein, we report two cases of vertebral osteomyelitis due to Bacteroides fragilis. It is noteworthy that cases of vertebral osteomyelitis due to Bacteroides fragilis have been attributed to the extension of intra-abdominal or pelvic floor infections. However, in the two cases described, there was no history of a previous medical intervention nor an intestinal or pelvic floor infection. Early recognition of the aetiological agent that causes vertebral osteomyelitis may lead to the timely treatment and therefore, may deter any neurosurgical/orthopaedic interventions.

High frequency of enterotoxigenic Bacteroides fragilis and Enterococcus faecalis in the paraffin-embedded tissues of Iranian colorectal cancer patients.

BACKGROUND: The association between specific bacteria and colorectal cancer (CRC) has been proposed. Only a few studies have, however, investigated this relationship directly in colorectal tissue with conflicting results. So, we aimed to quantitate Streptococcus gallolyticus, Fusobacterium spp, Enterococcus faecalis and enterotoxigenic Bacteroides fragilis (ETBF) in formalin-fixed and paraffin-embedded (FFPE) colorectal tissue samples of Iranian CRC patients and healthy controls. METHODS: A total of 80 FFPE colorectal tissue samples of CRC patients (n = 40) and healthy controls (n = 40) were investigated for the presence and copy number of above bacterial species using quantitative PCR. Relative quantification was determined using ΔΔCT method and expressed as relative fold difference compared to reference gene. RESULTS: Relative abundance and copy number of E. faecalis and ETBF were significantly higher in CRC samples compared to control group. E. faecalis was more prevalent than ETBF in tumor samples. Frequency of ETBF and E. faecalis in late stages (III/IV) of cancer was significantly higher than early stages (I/II). We did not detect a significant difference in abundance of S. gallolyticus and Fusobacterium spp between two groups. CONCLUSION: Our study revealed the higher concentration of E. faecalis and ETBF in FFPE samples of CRC patients than controls. However, additional investigations on fecal and fresh colorectal cancer tissue samples are required to substantiate this correlation.

What we actually know about the pathogenicity of Bacteroides pyogenes.

The aim of the study was to evaluate the pathogenic potential of Bacteroides pyogenes, rarely identified in clinical laboratories anaerobic bacteria. To increase the knowledge about this poorly understood anaerobic microorganism, the study also includes cases of infections described so far in the literature. Only the use of 16S rRNA sequencing and mass spectrometry technique allowed the identification of B. pyogenes from clinical specimens. We reported 13 severe human infections caused by B. pyogenes. Bacteria were cultured from the wound after biting by animals, chronic infections within the oral cavity, from patients with histologically or radiological proven osteomyelitis, surgical site infection, and from urine sample collected after a urological procedure. Most (9/13) of the patients required hospitalization. Almost 70% of them needed urgent admission via the emergency room. Two inpatients due to a life-threatening condition were admitted to the intensive care unit. Almost 50% of isolates were resistant to penicillin. All resistant to penicillin strains were isolated from skin and mucous membrane infections.

First case of an invasive Bacteroides dorei infection detected in a patient with a mycotic aortic aneurysm-raising a rebellion of major indigenous bacteria in humans: a case report and review.

BACKGROUND: Bacteroides dorei is an anaerobic gram-negative bacterium first described in 2006. Because of the high similarity in mass spectra between B. dorei and Bacteroides vulgatus, discriminating between these species is arduous in clinical practice. In recent decades, 16S rRNA gene sequencing has been a complementary method for distinguishing taxonomically close bacteria, including B. dorei and B. vulgatus, at the genus and species levels. Consequently, B. dorei has been shown to contribute to some diseases, including type 1 autoimmune diabetes mellitus and atherosclerotic diseases. However, there are no reports on invasive infectious diseases caused by B. dorei. This report describes the first case of direct invasion and colonisation of human tissue by B. dorei, thus providing a warning regarding the previously proposed application of B. dorei as a live biotherapeutic for atherosclerotic diseases. CASE PRESENTATION: A 78-year-old Japanese man complained of intermittent chest/back pain and was diagnosed with a mycotic thoracic aortic aneurysm by enhanced computed tomography on admission. Despite strict blood pressure control and empirical antibiotic therapy, the patient's condition worsened. To prevent aneurysmal rupture and eliminate infectious foci, the patient underwent surgical treatment. The resected specimen was subjected to tissue culture and 16S rRNA gene sequencing analysis to identify pathogenic bacteria. A few days after the surgery, culture and sequencing results revealed that the pathogen was B. dorei/B. vulgatus and B. dorei, respectively. The patient was successfully treated with appropriate antibacterial therapy and after improvement, was transferred to another hospital for rehabilitation on postoperative day 34. There was no recurrence of infection or aneurysm after the patient transfer. CONCLUSIONS: This report describes the first case of invasive infectious disease caused by B. dorei, casting a shadow over its utilisation as a probiotic for atherosclerotic diseases.

Rapid detection and surveillance of cfiA-positive Bacteroides fragilis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

OBJECTIVES: To perform surveillance of cfiA-positive Bacteroides fragilis using new subtyping software module, MALDI Biotyper Subtyping Module (MBT Subtyping Module), on MALDI-TOF MS system, and to evaluate the detection ability of the module. METHODS: cfiA-positive strains were presumed using the module against B. fragilis isolated between 2006 and 2019. The cfiA gene was confirmed using PCR. In cfiA-positive B. fragilis, the insertion sequence (IS) elements were examined and the MBT STAR-BL assay was performed to examine meropenem hydrolysis activity. RESULTS: Of the 396 B. fragilis strains included, the MBT Subtyping Module detected 33 presumptive cfiA-positive strains (8.3%), of which 32 harbored the cfiA gene. The sensitivity and specificity of the MBT Subtyping Module for detecting cfiA-positive B. fragilis were 100.0% and 99.7%, respectively. Of the 32 strains harboring the cfiA gene, seven strains possessed IS elements, which were thought to induce high cfiA expression. Meropenem hydrolysis was detected in all seven strains that were positive for both cfiA and IS elements, and they exhibited resistance to meropenem and imipenem. The overall non-susceptibility rates to meropenem and imipenem were 84.8% and 36.4%, respectively, in the 33 presumptive cfiA-positive strains. CONCLUSION: The MBT Subtyping Module can detect cfiA-positive B. fragilis rapidly and accurately, supporting its use for surveillance of cfiA-positive B. fragilis in clinical settings.

Bloodstream infection caused by Bacteroides denticanum, a close relative of Bacteroides pyogenes, misidentified by MALDI TOF- mass spectrometry.

Bacteroides pyogenes can cause infections in humans. We describe a case of bloodstream infection caused by Bacteroides denticanum that probably originated from a dog bite. MALDI-TOF MS misidentified this new species as B. pyogenes. Subsequent analysis using the 16S rRNA sequencing approach identified the species as B. denticanum.

A Novel Selective Medium for Isolation of Bacteroides fragilis from Clinical Specimens.

A novel Bacteroides fragilis selective (BFS) medium, consisting of a brain heart infusion agar base supplemented with yeast extract, cysteine hydrochloride, bile salts, vitamin K, hemin, glucose, esculin, ferric ammonium citrate, bromothymol blue, gentamicin, kanamycin, and novobiocin, was evaluated. When BFS agar was tested with a collection of 303 bacteria of different genera, it allowed the growth of B. fragilis as large yellow colonies, with blackening of the medium after 48 h of anaerobic incubation, while the growth of most other anaerobes, facultative anaerobes, and aerobes was inhibited. In a prospective comparison of BFS agar with a routinely used medium (neomycin blood agar) in 1,209 clinical specimens, 60 B. fragilis bacteria were detected on BFS agar while 46 were detected on the routine agar (McNemar's test, P = 0.008). In conclusion, this novel medium may be added to improve the recovery of B. fragilis in clinical specimens and to facilitate surveillance of antimicrobial-resistant strains.

Orthopedic infections caused by obligatory anaerobic Gram-negative rods: report of two cases.

Anaerobic bone and joint infections are uncommon, although the number of anaerobic infections is presumably underestimated because of difficulties with isolation and identification of obligate anaerobes. This study describes two cases of complicated Bacteroides fragilis peri-implant infection of the lumbar spine, infection of the hip and osteomyelitis. Bacteria were identified with the use of a mass spectrometer, VITEK MS system. Drug susceptibility was performed with the use of E-test. The EUCAST breakpoints were used for interpretation with B. fragilis ATCC 25285 as a control. In the two described cases clinical samples were collected for microbiological examination intraoperatively and simultaneously empirical treatment was applied. B. fragilis was isolated in monoculture or in a combination with other bacteria. The treatment was continued according to the susceptibility tests. In a case one clindamycin failure was observed and clindamycin resistance of the isolate was likely due to inadequate time of therapy. Difficulties in collecting an adequate samples and culturing anaerobic bacteria cause that not all infections are properly recognized. In a successful therapy, identification and determination of the susceptibility of the pathogen are essential as well as an appropriate surgical debridement.

First report of metronidazole resistant, nimD-positive, Bacteroides stercoris isolated from an abdominal abscess in a 70-year-old woman.

We here present the first case of a metronidazole resistant nimD positive Bacteroides stercoris. The isolate originated from a polymicrobial intra-abdominal abscess in a 70-year-old woman. The nimD gene was detected by use of whole-genome shotgun sequencing and the subsequent use of the ResFinder 2.1 web service.

Fatal sepsis caused by multidrug-resistant Bacteroides fragilis, harboring a cfiA gene and an upstream insertion sequence element, in Japan.

Here, we report a case of fatal sepsis resulting from an intra-abdominal infection caused by a Bacteroides fragilis strain containing a CfiA4 metallo-ß-lactamase and an upstream insertion sequence (IS) element. Meropenem was used as empiric therapy for septic shock as a result of the intra-abdominal infection, although two rounds of carbapenem treatment had been administered previously. B. fragilis was isolated from two anaerobic blood culture bottles 4 days after the onset of septic shock. Susceptibility testing revealed that the isolate was non-susceptible to all tested agents except metronidazole and tigecycline. The isolate gave a positive result in ethylenediaminetetraacetic acid and carbapenem inactivation tests, but a negative result in a double-disk synergy test using sodium mercaptoacetate. Next-generation whole-genome sequencing indicated the presence of the cfiA4, emrG and emrF genes. PCR indicated the presence of an IS element upstream of the cifA4 gene. Although carbapenem-resistant B. fragilis isolates have previously been reported, clinical sepsis by this organism is considered rare. In Japan, as in most countries worldwide, routine susceptibility testing and the detection of metallo-ß-lactamases is not carried out in anaerobic organisms, including B. fragilis. The emergence of carbapenem resistance during therapy should be monitored, as B. fragilis strains containing the cfiA gene show decreased sensitivity during carbapenem therapy. Therefore, susceptibility testing and appropriate antibiotic stewardship are required in cases of anaerobic bacterial infections.

Temporomandibular Joint Septic Arthritis and Mandibular Osteomyelitis Arising From an Odontogenic Infection: A Case Report and Review of the Literature.

Septic arthritis of the temporomandibular joint (TMJ) has been infrequently reported in the literature. Some investigators believe that this condition is under-reported because it is underdiagnosed. Misdiagnosis or late diagnosis of this condition can lead to serious morbidity, including fistula formation, intracranial abscess, fibrous or bony ankylosis, temporal bone or condylar osteomyelitis, growth alteration, and several others. This report describes a case of septic TMJ arthritis arising from direct spread of an odontogenic infection with subsequent development of mandibular osteomyelitis. The purpose of this case report is to 1) increase awareness of an underdiagnosed condition, 2) establish the seriousness of this infection, 3) for the first time report on a case of TMJ septic arthritis caused by Bacteroides infection, and 4) provide a review of the relevant literature.

Screening for enterotoxigenic Bacteroides fragilis in stool samples.

Bacteroides fragilis is a commensal bacterium found in the gut of most humans, however enterotoxigenic B. fragilis strains (ETBF) have been associated with diarrhoea and colorectal cancer (CRC). The purpose of this study was to establish a method of screening for the Bacteroides fragilis toxin (bft) gene in stool samples, as a means of determining if carriage of ETBF is detected more often in CRC patients than in age-matched healthy controls. Stool samples from 71 patients recently diagnosed with CRC, and 71 age-matched controls, were screened by standard and quantitative PCR using primers specific for the detection of the bft gene. Bacterial template DNA from stool samples was prepared by two methods: a sweep, where all colonies growing on Bacteroides Bile Esculin agar following stool culture for 48 h at 37 °C in an anaerobic environment were swept into sterile water and heat treated; and a direct DNA extraction from each stool sample. The bft gene was detected more frequently from DNA isolated from bacterial sweeps than from matched direct DNA extractions. qPCR was found to be more sensitive than standard PCR in detecting bft. The cumulative total of positive qPCR assays from both sample types revealed that 19 of the CRC patients had evidence of the toxin gene in their stool sample (27%), compared to seven of the age-matched controls (10%). This difference was significant (P = 0.016). Overall, ETBF carriage was detected more often in CRC patient stool samples compared to controls, but disparate findings from the different DNA preparations and testing methods suggests that poor sensitivity may limit molecular detection of ETBF in stool samples.

First case report of a human sepsis involving a recently identified anaerobic agent: Bacteroides faecis.

Up until now, Bacteroides faecis, a Gram-negative, anaerobic, non-motile, nonsporeforming rod has been principally described as a commensal microbe isolated from the feces of healthy adults. We report the first case of human Bacteroides faecis sepsis after removal of suspected post-colonic ischemia colonized epicardic electrodes. Electrodes and blood cultures both grew Gram-negative anaerobic rods but usual phenotypic methods and 16S rARN gene sequencing failed to ensure its species identification. B. faecis was finally identified using hsp60 gene sequencing. Because this species is not well-known and is difficult to identify, it may have been overlooked or misidentified in previous studies.

A case of Bacteroides pyogenes bacteremia secondary to liver abscess.

Bacteroides pyogenes, a non-spore-forming, anaerobic, gram-negative rod, is a component of the oral flora of animals and has, on occasion, been reported to cause human infection through dog or cat bites. We report the first case of B. pyogenes bacteremia secondary to liver abscess with no history of an animal bite. The microorganism was identified by 16S rRNA sequencing.

Anaerobic bacteraemia: a 10-year retrospective epidemiological survey.

In order to identify current trends in anaerobic bacteraemia, a 10-year retrospective study was performed in the University Hospital Brussel, Belgium. All clinically relevant bacteraemia detected from 2004 until 2013 were included. Medical records were reviewed in an attempt to define clinical parameters that might be associated with the occurrence of anaerobic bacteraemia. 437 of the isolated organisms causing anaerobic bacteraemia were thawed, subcultured and reanalyzed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). There were an average of 33 cases of anaerobic bacteraemia per year during 2004-2008 compared to an average of 27 cases per year during 2009-2013 (P = 0.017), corresponding to a decrease by 19% between the first and the latter period. Also, the total number of cases of anaerobic bacteraemia per 100,000 patient days decreased from 17.3 in the period from 2004 to 2008 to 13.7 in the period 2009 to 2013 (P = 0.023). Additionally, the mean incidence of anaerobic bacteraemia decreased during the study period (1.27/1000 patients in 2004 vs. 0.94/1000 patients in 2013; P = 0.008). In contrast, the proportion of isolated anaerobic bacteraemia compared to the number of all bacteraemia remained stable at 5%. Bacteroides spp. and Parabacteroides spp. accounted for 47.1% of the anaerobes, followed by 14.4% Clostridium spp., 12.6% non-spore-forming Gram-positive rods, 10.5% anaerobic cocci, 8.2% Prevotella spp. and other Gram-negative rods and 7.1% Fusobacterium spp. The lower gastrointestinal tract (47%) and wound infections (10%) were the two most frequent sources for bacteraemia, with the origin remaining unknown in 62 cases (21%). The overall mortality rate was 14%. Further studies focusing on the antimicrobial susceptibility and demographic background of patients are needed to further objectify the currently observed trends.

Fecal detection of enterotoxigenic Bacteroides fragilis.

Bacteroides fragilis is a common colonic symbiote of which one subtype, enterotoxigenic Bacteroides fragilis (ETBF), causes inflammatory diarrhea. However, asymptomatic ETBF colonization is common. Through its primary virulence factor, B. fragilis toxin (BFT), ETBF causes asymptomatic, chronic colitis in C57BL/6 mice and increased colon tumorigenesis in multiple intestinal neoplasia mice. Human studies suggest an association between ETBF infection, inflammatory bowel disease, and colon cancer. Additional studies on ETBF epidemiology are, therefore, crucial. The goal of this study is to develop a reliable fecal diagnostic for ETBF. To develop a sensitive assay for ETBF, we tested multiple protocols on mouse stools spiked with serially diluted ETBF. Each assay was based on either touchdown or quantitative polymerase chain reaction (qPCR) and used primers targeted to bft to detect ETBF. Using touchdown PCR or qPCR, the mean ETBF detection limit was 1.55 × 10(6) colony-forming units (CFU)/g stool and 1.33 × 10(4) CFU/g stool, respectively. Augmentation of Bacteroides spp. growth in fecal samples using PYGB (Peptone Yeast Glucose with Bile) broth enhanced ETBF detection to 2.93 × 10(2) CFU/g stool using the touchdown PCR method and 2.63 × 10(2) CFU/g stool using the qPCR method. Fecal testing using combined culture-based amplification and bft touchdown PCR is a sensitive assay for the detection of ETBF colonization and should be useful in studying the role of ETBF colonization in intestinal diseases, such as inflammatory bowel disease and colon cancer. We conclude that touchdown PCR with culture-based amplification may be the optimal ETBF detection strategy, as it performs as well as qPCR with culture-based amplification, but is a less expensive technique.