Association of Bacillus circulans with non-diabetic foot infection in Bangladeshi patient

Bombyx mori as a model for Niallia circulans pathogenicity

Increasing incidences of resistance to antibiotics by pathogenic bacteria is a worldwide concern and isolation of antibiotic-resistant strains of Niallia circulans (formerly known as Bacillus circulans), an opportunistic human pathogen, has been reported. Due to their lack of ethical constraints as well as their cost-effective rearing, invertebrates have been commonly used to study infection by bacteria pathogenic to humans. In this study, we demonstrate that a foodborne strain of N. circulans kills larvae of the silkworm, Bombyx mori within 48 h after hemolymph injection. The infected larvae turned black with an increase in the phenoloxidase (PO) activity in the hemolymph. Midgut injection of N. circulans resulted in the killing of larvae within 96 h. A significant increase in bacterial load was observed in the hemolymph 12 h after infection. The viable hemocyte number decreased to 48% within 12 h of injection. RT-qPCR analysis revealed that upon hemolymph infection with N. circulans the expression of the antimicrobial peptide (AMP) genes, Bmdefensin-B and Bmgloverin-3, were upregulated 2.5- and 1.8-fold, respectively, whereas 1.6-fold upregulation was observed for BmToll-2 in the larval fat body. Therapeutic effects of antibiotics like tetracycline, imipenem, ceftriaxone, ampicillin, and clindamycin were observed against N. circulans in the Bombyx larvae with varying efficacies. Results from this study suggest that larvae of B. mori can be used as infection models for screening therapeutics that are effective against N. circulans.

First report of spondylodiscitis caused by Bacillus circulans in an immunocompetent patient: Clinical case and review of the literature

Bacillus circulans is mainly considered an opportunistic pathogen in immunocompromised patients. However, many different infections have been described in the literature: bacteremia, abscesses, meningitis, endophthalmitis, and wound infections. We observed a spondylodiscitis caused by Bacillus circulans in an immunocompetent patient. To date, this is the first case reported in literature. Vertebral osteomyelitis represents for clinicians a challenging infection to manage and treat, because of its insidious and indolent course. The diagnosis is frequently difficult and can often be delayed for several months and initially be misdiagnosed and mismanaged. For this reason, the clinical case was described and all published cases of infection caused by Bacillus circulans were reviewed.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 13: suitability of taxonomic units notified to EFSA until September 2020

The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of biological agents, intended for addition to food or feed, to support the work of EFSA's Scientific Panels. It is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of knowledge, safety concerns and antimicrobial resistance. Safety concerns identified for a taxonomic unit (TU) are, where possible, confirmed at strain or product level, and reflected by 'qualifications'. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS TUs. Of the 36 microorganisms notified to EFSA between April and September 2020, 33 were excluded; seven filamentous fungi (including Aureobasidium pullulans based on recent taxonomic insights), one Clostridium butyricum, one Enterococcus faecium, three Escherichia coli, one Streptomyces spp. and 20 TUs that had been previously evaluated. Three TUs were evaluated; Methylorubrum extorquens and Mycobacterium aurum for the first time and Bacillus circulans was re-assessed because an update was requested in relation to a new mandate. M. extorquens and M. aurum are not recommended for QPS status due to the lack of a body of knowledge in relation to use in the food or feed chain and M. aurum, due to uncertainty concerning its pathogenicity potential. B. circulans was recommended for QPS status with the qualifications for 'production purposes only' and 'absence of cytotoxic activity'.

Insights into Antagonistic Interactions of Multidrug Resistant Bacteria in Mangrove Sediments from the South Indian State of Kerala

Antibiotic resistance is a global issue which is magnified by interspecies horizontal gene transfer. Understanding antibiotic resistance in bacteria in a natural setting is crucial to check whether they are multidrug resistant (MDR) and possibly avoid outbreaks. In this study, we have isolated several antibiotic-resistant bacteria (ARB) (n = 128) from the mangroves in Kerala, India. ARBs were distributed based on antibiotics (p = 1.6 × 10^-5). The 16S rRNA gene characterization revealed dominance by Bacillaceae (45%), Planococcaceae (22.5%), and Enterobacteriaceae (17.5%). A high proportion of the isolates were MDR (75%) with maximum resistance to methicillin (70%). Four isolates affiliated to plant-growth promoters, probiotics, food, and human pathogens were resistant to all antibiotics indicating the seriousness and prevalence of MDR. A significant correlation (R = 0.66; p = 2.5 × 10^-6) was observed between MDR and biofilm formation. Antagonist activity was observed in 62.5% isolates. Gram-positive isolates were more susceptible to antagonism (75.86%) than gram-negative (36.36%) isolates. Antagonism interactions against gram-negative isolates were lower (9.42%) when compared to gram-positive isolates (89.85%). Such strong antagonist activity can be harnessed for inspection of novel antimicrobial mechanisms and drugs. Our study shows that MDR with strong biofilm formation is prevalent in natural habitat and if acquired by deadly pathogens may create havoc in public health.