Brain abscesses in children are uncommon but serious conditions. Bifidobacterium species, typically considered commensal organisms of the oral cavity, gastrointestinal tract, and female genital tract, are rarely implicated in invasive infections. We present a case of multiple brain abscesses caused by Bifidobacterium spp. in a previously healthy 11-year-old male, secondary to contiguous spread from chronic left-sided paranasal sinusitis with ethmoid bone erosion. Neuroimaging demonstrated left frontal abscesses with marked perilesional edema, ring enhancement and midline shift, together with opacification of the left maxillary, ethmoid and frontal sinuses. Bifidobacterium spp. was the only organism isolated from both the brain abscess aspirate and the sinus samples. The patient was treated with burr-hole aspiration of the abscesses and same-session endoscopic sinus surgery, followed by six weeks of intravenous crystalline penicillin G. He achieved full clinical recovery without neurological sequelae, with stable residual changes on follow-up MRI. To our knowledge, this is the first detailed case report of a brain abscess caused by Bifidobacterium spp. in a previously healthy pediatric patient. This case highlights the potential of this typically commensal organism to cause serious central nervous system infection via contiguous spread from the paranasal sinuses.

Clostridioides difficile infection (CDI) remains a major cause of antibiotic-associated diarrhea and colitis, with a high rate of recurrence. Current CDI treatments rely largely on antibiotics that perpetuate dysbiosis or on microbiota-based interventions with limited accessibility, emphasizing the need to explore novel, targeted microbiota-derived therapies. Probiotics have emerged as a potential approach for the prevention and management of CDI, owing to their capacity to modulate the gut microbiota and host immune responses. Among them, bifidobacteria are prominent commensal anaerobes of the human gut with well-documented health-promoting properties. Although their role in CDI has been less extensively explored than that of other probiotic microorganisms, accumulating evidence suggests that bifidobacteria may exert both direct antagonistic effects against C. difficile and indirect benefits through the restoration of eubiosis and attenuation of inflammation. This review summarizes recent in vitro, in vivo, and clinical studies investigating the effects of bifidobacteria in the context of CDI. We discuss mechanisms including inhibition of C. difficile growth and toxin activity, modulation of host inflammatory responses, and interactions with the intestinal microbiota. Particular attention is given to studies published over the past decade. Overall, bifidobacteria emerge as promising candidates for future probiotic or microbiota-based interventions targeting CDI, although further well-designed clinical trials are needed to establish their efficacy and optimal modes of use.

We previously identified an intact Enterobacteriaceae-derived plasmid (pCA17) in the draft genome sequence of C. acnes strain CA17. In the absence of this isolate for laboratory confirmation, we performed in silico analyses, including comparative gene synteny, replicon typing, GC content, and CAI analysis, supporting pCA17 as a likely contaminant.

Clostridium tetani, the causative agent of tetanus, is an important pathogen in human and veterinary medicine. This study characterized three C. tetani isolates from black vultures (Coragyps atratus) in Brazil, using whole-genome sequencing. The chromosomal and plasmid genomes were highly conserved, showing low SNP variability among the isolates. ANI and dDDH analyses confirmed that all isolates belonged to C. tetani. Virulence-associated genes (TeNT, colT, and tly) were detected in all isolates. Phylogenetic analysis indicated that these isolates were closely related to strains recovered from food and human clinical sources.

Staphylococcus saccharolyticus is a slow-growing anaerobic coagulase-negative staphylococcus and a rare cause of bloodstream infections. We report the case of a previously healthy 35-year-old woman who presented with fever and headache. One anaerobic bottle from each of two separately collected blood culture sets became positive after 53 h, and S. saccharolyticus was identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; both aerobic bottles remained negative. No focus of infection was detected. Repeat cultures drawn on day 3, before vancomycin treatment was started, were already negative. The patient received ceftriaxone for 3 days, vancomycin for 4 days, and oral clindamycin for 8 days, and recovered without relapse. The minimum inhibitory concentrations were obtained using a panel developed for aerobically growing gram-positive cocci and were reported without categorical interpretation, as no breakpoints have been validated for this species. Detection in two separately collected sets may represent true bacteremia even in the absence of an implanted device or comorbidity.

The role of type 2 immunity in protection against C. difficile infection (CDI) has recently become better appreciated, prompting further exploration into mechanistic underpinnings of host response to infection. Though it is known that abundance of type 2 effector cells negatively correlates with CDI severity in mice and humans and that experimental treatment with those effectors or type 2-promoting cytokines protects against severe disease, the underlying signaling pathways and downstream functions of effector cells remain unclear. Group 2 innate lymphoid cells (ILC2s), eosinophils, and alternatively activated macrophages (AAMs) have been identified as mediators of type 2 protection in CDI. ILC2s have been the most well-characterized thus far, as their stimulation by type 2 alarmins induces downstream effects on immune and epithelial cell processes. Eosinophils may contribute to enhanced tissue repair, immunomodulation, or antimicrobial effects during CDI, but their functional roles have not yet been defined. Alternatively activated macrophages may also contribute to tissue repair, though more mechanistic work must be performed to determine this. In this mini-review, we summarize existing knowledge of type 2-mediated protection in CDI and identify open areas of research and potential cells and signaling molecules of interest for future functional and mechanistic interrogation. Given the demonstrated importance of type 2 immunity in human and experimental CDI, these studies will be essential in the development of immunotherapeutic interventions for acute and recurrent CDI.