Bacillus cereus, a volatile human pathogen

Targeting bacterial growth in biofilm conditions: rational design of novel inhibitors to mitigate clinical and food contamination using QSAR

Antimicrobial resistance (AMR) is a pressing global issue exacerbated by the abuse of antibiotics and the formation of bacterial biofilms, which cause up to 80% of human bacterial infections. This study presents a computational strategy to address AMR by developing three novel quantitative structure-activity relationship (QSAR) models based on molecular topology to identify potential anti-biofilm and antibacterial agents. The models aim to determine the chemo-topological pattern of Gram (+) antibacterial, Gram (-) antibacterial, and biofilm formation inhibition activity. The models were applied to the virtual screening of a commercial chemical database, resulting in the selection of 58 compounds. Subsequent in vitro assays showed that three of these compounds exhibited the most promising antibacterial activity, with potential applications in enhancing food and medical device safety.

Antimicrobial and Phylogenomic Characterization of Bacillus cereus Group Strains Isolated from Different Food Sources in Italy

Background:Bacillus cereus is a widespread environmental Gram-positive bacterium which is especially common in soil and dust. It produces two types of toxins that cause vomiting and diarrhea. At present, foodborne outbreaks due to Bacillus cereus group bacteria (especially Bacillus cereus sensu stricto) are rising, representing a serious problem in the agri-food supply chain. Methods: In this work, we analyzed 118 strains belonging to the Bacillus cereus group, isolated from several food sources, for which in vitro and in silico antibiotic resistance assessments were performed. Results: Many strains showed intermediate susceptibility to clindamycin, erythromycin, and tetracycline, suggesting an evolving acquisition of resistance against these antibiotics. Moreover, one strain showed intermediate resistance to meropenem, an antibiotic currently used to treat infections caused by Bacillus cereus. In addition to the phenotypic antimicrobial resistance profile, all strains were screened for the presence/absence of antimicrobial genes via whole-genome sequencing. There was inconsistency between the in vitro and in silico analyses, such as in the case of vancomycin, for which different isolates harbored resistance genes but, phenotypically, the same strains were sensitive. Conclusions: This would suggest that antibiotic resistance is a complex phenomenon due to a variety of genetic, epigenetic, and biochemical mechanisms.

Exertional heat stress promotes the presence of bacterial DNA in plasma: A counterbalanced randomised controlled trial

OBJECTIVES

The primary aim was to explore the impact of exertional-heat stress (EHS) promoted exercise-associated bacteraemia. A secondary aim was to examine if an amino acid beverage (AAB) intervention may mitigate exercise-associated bacteraemia.

DESIGN

Counterbalanced randomised control trial.

METHODS

Twenty endurance trained male participants completed two randomised EHS trials. On one occasion, participants consumed a 237 mL AAB twice daily for 7 days prior, immediately before and every 20 min during EHS (2 h running at 60 % V̇O2max in 35 °C). On the other occasion, a water volume control (CON) equivalent was consumed. Whole blood samples were collected pre- and immediately post-EHS, and were analysed for plasma DNA concentration by fluorometer quantification after microbial extraction, and bacterial relative abundance by next generation 16s rRNA gene sequencing.

RESULTS

Increased concentration of microbial DNA in plasma pre- to post-EHS was observed on CON (pre-EHS 0.014 ng/μL, post-EHS 0.039 ng/μL) (p < 0.001) and AAB (pre-EHS 0.015 ng/μL, post-EHS 0.031 ng/μL) (p < 0.001). The magnitude of change from pre- to post-exercise on AAB was 40 % lower, but no significant difference was observed versus CON (p = 0.455). Predominant bacterial groups identified included: phyla-Proteobacteria (88.0 %), family-Burkholderiaceae (59.1 %), and genus-Curvibacter (58.6 %). No significant variation in absolute and relative change in α-diversity and relative abundance for phyla, family, and genus bacterial groups was observed in AAB versus CON.

CONCLUSIONS

The increased presence of microbial-bacterial DNA in systemic circulation in response to EHS appears positive in all participants. An amino acid beverage supplementation period prior to and consumption during EHS did not provide significant attenuation of EHS-associated bacteraemia.

Genomic Insights into the Pathogenicity and Drug-Resistance of a Bacillus cereus Isolated from Human Teeth

Background

Bacillus cereus is a common bacterium found in the environment. Some strains can cause food poisoning, and very few can cause clinically severe infections, leading to death. Here, we characterized the genome sequence of B. cereus LIN78 isolated from teeth with deep caries and compared it with those of 25 other related species.

Methods

Third-generation sequencing technology, bacteriological analyses, biochemistry, and mass spectrometry were applied to characterize the drug-resistance genes and virulence factors of B. cereus LIN78.

Results

The complete genome sequence of B. cereus Lin78 consists of 5647 genes distributed on a circular chromosome, a 393 kbp plasmid, and 928 pseudogenes (37.4% of whole-genome DNA). The LIN78 genome contains 14 sets of 16s, 23s, and 5s ribosomal RNA operons; 106 tRNA genes, one tmRNA, 12 genomic islands, six prophases, 64 repeats; 37 antibiotic-resistant genes; and 1119 putative virulence genes, including enterotoxins and cytolysins. The B. cereus LIN78 genome carries multiple copies of non-ribosomal polypeptide synthetase (NRPS) and post-translationally modified peptides (RiPPs). Phylogenetic analysis of the 26 B. cereus strains showed that B. cereus LIN78 is evolutionarily closely related to B. thuringiensis ATCC 10792 and B. cereus ATCC 14579.

Conclusion

The newly isolated B. cereus carries many virulence genes, including enterotoxins and hemolysins, similar to B. anthracis, and multiple antibiotic resistance genes. These findings suggest that the strain has a potential risk of causing disease. Our studies are vital for further exploration of the evolution of B. cereus, its pathogenic mechanisms, and the control and treatment of bacterial infections.

Multi-omics analysis of gut microbiota and metabolites reveals contrasting profiles in domestic pigs and wild boars across urban environments

The gut microbiota plays a crucial role in host health and metabolism. This study explores the differences in gut microbiota and metabolites between domestic pigs (DP) and wild boars (WB) in urban environments. We analyzed gut microbial composition, metabolic profiles, virome composition, antibiotic resistance genes (ARGs), and human pathogenic bacteria (HPB) in both DP and WB. Our results revealed that DP exhibited a higher Firmicutes/Bacteroidetes ratio and were enriched in bacterial genera associated with domestication and modern feeding practices. Metabolomic analysis showed distinct profiles, with WB significantly enriched in the Pantothenate and CoA biosynthesis pathway, highlighting dietary and environmental influences on host metabolism. Additionally, DP had a distinct gut virome composition, particularly enriched in lytic phages of the Chaseviridae family. ARG analysis indicated a higher abundance of tetracycline resistance genes in DP, likely due to antibiotic use in pig farms. Furthermore, variations in HPB composition underscored potential health risks associated with contact with pig feces. These findings provide valuable insights into the microbial ecology of domestic pigs and wild boars, emphasizing the importance of these comparisons in identifying zoonotic pathogen transmission pathways and managing antibiotic resistance. Continued research in this area is essential for developing effective strategies to mitigate public health risks and promote sustainable livestock management practices.

Assessment of chlorine and hydrogen peroxide on airborne bacteria: Disinfection efficiency and induction of antibiotic resistance

Airborne pathogens severely threaten public health worldwide. Air disinfection is essential to ensure public health. However, excessive use of disinfectants may endanger environmental and ecological security due to the residual disinfectants and their by-products. This study systematically evaluated disinfection efficiency, induction of multidrug resistance, and the underlying mechanisms of disinfectants (NaClO and H2O2) on airborne bacteria. The results showed that airborne bacteria were effectively inactivated by atomized NaClO (>160 μg/L) and H2O2 (>320 μg/L) after 15 min. However, some bacteria still survived after disinfection by atomized NaClO (0-80 μg/L) and H2O2 (0-160 μg/L), and they exhibited significant increases in antibiotic resistance. The whole-genome sequencing of the resistant bacteria revealed distinct mutations that were responsible for both antibiotic resistance and virulence. This study also provided evidences and insights into possible mechanisms underlying the induction of antibiotic resistance by air disinfection, which involved intracellular reactive oxygen species formation, oxidative stress responses, alterations in bacterial membranes, activation of efflux pumps, and the thickening of biofilms. The present results also shed light on the role of air disinfection in inducing antibiotic resistance, which could be a crucial factor contributing to the global spread of antibiotic resistance through the air.

Bacterial diversity in Buruli ulcer lesions in Ghana

Background

Previous studies have demonstrated secondary microbial infection of Buruli ulcer (BUD) lesions before, during and after treatment. However, there is limited data on the bacterial diversity across treatment and their influence on clinical outcome. The present study aimed to investigate the relationship between bacterial diversity within BUD lesions and clinical outcome in affected individuals.

Methods

We investigated the bacterial diversity within lesions of individuals with PCR confirmed BUD from 5 endemic districts within central Ghana. Samples were collected longitudinally from lesions over treatment period. Microbiological analyses including isolation of bacteria, and species identification were performed using the VITEK 2 compact.

Results

Out of 36 participants included, 80.5 % presented with ulcers on the lower limbs. Higher bacterial diversity was observed in ulcers compared to other clinical forms of BUD. There was a significant association between bacterial diversity and clinical outcome (p = 0.002). ESBL producing bacteria and MRSA were isolated in slow healing BUD lesions.

Conclusion

Higher diversity of secondary organisms colonizing BUD lesions may have an impact on clinical outcome in affected individuals. There is the need for the development of treatment guidelines for simultaneous management of M. ulcerans and other potential pathogens within lesions to improve clinical outcome.

Sliding motility of Bacillus cereus mediates vancomycin pseudo-resistance during antimicrobial susceptibility testing

BACKGROUND

The glycopeptide vancomycin is the antimicrobial agent-of-choice for the treatment of severe non-gastrointestinal infections with members of Bacillus cereus sensu lato (s.l.). Recently, sporadic detection of vancomycin-resistant phenotypes emerged, mostly for agar diffusion testing such as the disc diffusion method or gradient test (e.g. Etest®) method.

RESULTS

In this work, we were able to disprove a preliminarily assumed high resistance to vancomycin in an isolate of B. cereus s.l. using broth microdilution and agar dilution. Microscopic imaging during vancomycin susceptibility testing showed spreading towards the inhibition zone, which strongly suggested sliding motility. Furthermore, transcriptomic analysis using RNA-Seq on the nanopore platform revealed several key genes of biofilm formation (e.g. calY, tasA, krsEABC) to be up-regulated in pseudo-resistant cells, substantiating that bacterial sliding is responsible for the observed mobility. Down-regulation of virulence (e.g. hblABCD, nheABC, plcR) and flagellar genes compared with swarming cells also confirmed the non-swarming phenotype of the pseudo-resistant isolate.

CONCLUSIONS

The results highlight an insufficiency of agar diffusion testing for vancomycin susceptibility in the B. cereus group, and reference methods like broth microdilution are strongly recommended. As currently no guideline mentions interfering phenotypes in antimicrobial susceptibility testing of B. cereus s.l., this knowledge is essential to obtain reliable results on vancomycin susceptibility. In addition, this is the first report of sliding motility undermining accurate antimicrobial susceptibility testing in B. cereus s.l. and may serve as a basis for future studies on bacterial motility in susceptibility testing and its potential impact on treatment efficacy.

Fungal and bacterial species on biowaste workers' hands and inhalation zone, and potential airway deposition

This study aims to investigate the microbiological working environment of biowaste workers, focusing on airborne fungal and bacterial species exposure, size distribution, and species on workers' hands. The research, conducted across six plants with 45 personal exposure assessments, revealed a total of 150 bacterial species and 47 fungal species on workers' hands, including 19 and 9 species classified in risk class 2 (RC2), respectively. Workers' exposure analysis identified 172 bacterial and 32 fungal species, with several in RC2. In work areas, 55 anaerobic bacterial species belonging to RC2 were found. Different species compositions were observed in various particle size fractions, with the highest species richness for anaerobic bacteria in the fraction potentially depositing in the secondary bronchi and for fungi in the pharynx fraction. The geometric mean aerodynamic diameter (DG) of RC2 anaerobic bacteria was 3.9 µm, <1.6 µm for Streptomyces, 3.4 µm for Aspergillus, and 2.0 µm for Penicillium. Overlapping species were identified on workers' hands, in their exposure, and in work areas, with Bacillus amyloliquefaciens, Leuconostoc mesenteroides, Bacillus cereus, Enterococcus casseliflavus, and Aspergillus niger consistently present. While the majority of RC2 bacterial species lacked documented associations with occupational health problems, certain bacteria and fungi, including Bacillus cereus, Escherichia coli, Enterobacter, Klebsiella pneumonia, Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, Lichtheimia corymbifera, Lichtheimia ramosa, and Paecilomyces variotii, have previously been linked to occupational health issues. In conclusion, biowaste workers were exposed to a wide range of microorganisms including RC2 species which would deposit in different parts of the airways.

Antimicrobial Potential of Pomegranate and Lemon Extracts Alone or in Combination with Antibiotics against Pathogens

Amidst the growing concern of antimicrobial resistance as a significant health challenge, research has emerged, focusing on elucidating the antimicrobial potential of polyphenol-rich extracts to reduce reliance on antibiotics. Previous studies explored the antifungal effects of extracts as potential alternatives to conventional therapeutic strategies. We aimed to assess the antibacterial and antifungal effects of standardised pomegranate extract (PE) and lemon extract (LE) using a range of Gram-negative and Gram-positive bacteria and two yeast species. Additionally, we assessed the antimicrobial activities of common antibiotics (Ciprofloxacin, Imipenem, Gentamicin, and Ceftazidime), either alone or in combination with extracts, against Staphylococcus aureus and Escherichia coli. PE displayed substantial antibacterial (primarily bactericidal) and antifungal effects against most pathogens, while LE exhibited antibacterial (mostly bacteriostatic) and antifungal properties to a lesser extent. When compared with antibiotics, PE showed a greater zone of inhibition (ZOI) than Ciprofloxacin and Ceftazidime (p < 0.01) and comparable ZOI to Gentamicin (p = 0.4) against Staphylococcus aureus. However, combinations of either PE or LE with antibiotics exhibited either neutral or antagonistic effects on antibiotic activity against Staphylococcus aureus and Escherichia coli. These findings contribute to the existing evidence regarding the antimicrobial effects of PE and LE. They add to the body of research suggesting that polyphenols exert both antagonistic and synergistic effects in antimicrobial activity. This highlights the importance of identifying optimal polyphenol concentrations that can enhance antibiotic activity and reduce antibiotic resistance. Further in vivo studies, starting with animal trials and progressing to human trials, may potentially lead to recommendation of these extracts for therapeutic use.

An RPA-Assisted CRISPR/Cas12a Assay Combining Fluorescence and Lateral Flow Strips for the Rapid Detection of Enterotoxigenic Bacillus cereus

Bacillus cereus (B. cereus) is a foodborne pathogen that can produce tripartite enterotoxins, which can cause a variety of diseases after infection. It is critical to rapidly and accurately detect strains with enteropathogenic potential to safeguard human health. In this study, a dual-signal visualized detection platform with fluorescence assay and paper-based lateral flow assay (LFA) based on recombinase polymerase amplification (RPA), CRISPR/Cas12a system, and self-developed CRISPR nucleic acid test strips was constructed for enterotoxigenic B. cereus. The genes that encode two tripartite enterotoxins─nheA, nheB, and nheC for nonhemolytic enterotoxin and hblA, hblC, and hblD for hemolysin BL─were utilized as detection targets. The platform was capable of detecting six enterotoxin genes at the same genomic DNA level. The limits of detection for each gene were 10-3 ng/μL in fluorescence assay and 10-4 ng/μL in LFA. Furthermore, 101-102 CFU/mL of B. cereus in pure culture was detected. Additionally, a smartphone miniprogram could assist in evaluating the results in LFA. The platform demonstrated good utility by detecting B. cereus in food samples, including milk and rice. The results indicate that our RPA-CRISPR/Cas12a dual-signal visualized detection platform can quickly and easily detect B. cereus with three-component enterotoxin-producing potentials. The whole analytic process took less than 60 min without complex operation or expensive equipment.

Degradation of Toxins Derived from Foodborne Pathogens by Atmospheric-Pressure Dielectric-Barrier Discharge

Foodborne diseases can be attributed not only to contamination with bacterial or fungal pathogens but also their associated toxins. Thus, to maintain food safety, innovative decontamination techniques for toxins are required. We previously demonstrated that an atmospheric-pressure dielectric-barrier discharge (APDBD) plasma generated by a roller conveyer plasma device is effective at inactivating bacteria and fungi in foods. Here, we have further examined whether the roller conveyer plasma device can be used to degrade toxins produced by foodborne bacterial pathogens, including aflatoxin, Shiga toxins (Stx1 and Stx2), enterotoxin B and cereulide. Each toxin was spotted onto an aluminum plate, allowed to dry, and then treated with APDBD plasma applied by the roller conveyer plasma device for different time periods. Assessments were conducted using a competitive enzyme-linked immunosorbent assay (ELISA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results demonstrate a significant time-dependent decrease in the levels of these toxins. ELISA showed that aflatoxin B1 concentrations were reduced from 308.6 µg/mL to 74.4 µg/mL within 1 min. For Shiga toxins, Stx1 decreased from 913.8 µg/mL to 65.1 µg/mL, and Stx2 from 2309.0 µg/mL to 187.6 µg/mL within the same time frame (1 min). Enterotoxin B levels dropped from 62.67 µg/mL to 1.74 µg/mL at 15 min, and 1.43 µg/mL at 30 min, but did not display a significant decrease within 5 min. LC-MS/MS analysis verified that cereulide was reduced to below the detection limit following 30 min of APDBD plasma treatment. Taken together, these findings highlight that a range of foodborne toxins can be degraded by a relatively short exposure to plasma generated by an APDBD using a roller conveyer device. This technology offers promising advancements in food safety, providing a novel method to alleviate toxin contamination in the food processing industry.

Thrombus Tango: Hypercoagulable State With a Right Atrial Mass and Superimposed Persistent Bacteremia

Bacillus cereus is an uncommon nosocomial bacteria, typically dismissed as a contaminant. This case is a unique scenario in which B. cereus bacteremia persisted despite appropriate treatment. Further investigation revealed the presence of a right atrial thrombus believed to harbor a biofilm responsible for the sustained bacteremia. Clearance of the thrombus using the AngioVac system (AngioDynamics, Inc., Latham, NY) led to the resolution of blood cultures, and subsequently, the patient was discharged with a six-week course of intravenous (IV) antibiotics.

A case of prosthetic valve endocarditis and aortic abscess due to Bacillus cereus

Bacillus cereus (B. cereus) is commonly found in the environment and is often considered a blood culture contaminant. However, in patients with specific risk factors such as intravenous drug use, central venous access catheters, immunosuppression, or prosthetic valves, B. cereus can cause severe infections. Herein, we present a case of prosthetic valve endocarditis (PVE) caused by B. cereus in an 84-year-old woman with a history of aortic valve replacement for aortic stenosis five years earlier. She presented with anorexia, and her physical examination revealed tenderness in the left upper quadrant of the abdomen. Blood culture grew B. cereus, and a CT scan showed splenic infarction, raising suspicion of PVE. Transesophageal echocardiogram (TEE) revealed an abscess around the left coronary cusp of the aortic valve and a 15 mm vegetation. Due to the patient's high risk for post-operative complications and her unwillingness to undergo surgery, the surgery was deferred. Instead, she was successfully treated with six weeks of intravenous vancomycin and discharged home. Follow-up TEE demonstrated resolution of the vegetation and valvular abscess. At her six-month post-discharge evaluation, no signs of active infection were noted including fever or worsening heart failure. Although surgery is typically recommended for most cases of PVE, conservative treatment can be considered as an alternative option for selected patients.

Exploring the Genomic Landscape of Bacillus paranthracis PUMB_17 as a Proficient Phosphatidylcholine-Specific Phospholipase C Producer

Phospholipases find versatile applications across industries, including detergent production, food modification, pharmaceuticals (especially in drug delivery systems), and cell signaling research. In this study, we present a strain of Bacillus paranthracis for the first time, demonstrating significant potential in the production of phosphatidylcholine-specific phospholipase C (PC-PLC). The investigation thoroughly examines the B. paranthracis PUMB_17 strain, focusing on the activity of PC-PLC and its purification process. Notably, the PUMB_17 strain displays extracellular PC-PLC production with high specific activity during the late exponential growth phase. To unravel the genetic makeup of PUMB_17, we employed nanopore-based whole-genome sequencing and subsequently conducted a detailed genome annotation. The genome comprises a solitary circular chromosome spanning 5,250,970 bp, featuring a guanine-cytosine ratio of 35.49. Additionally, two plasmids of sizes 64,250 bp and 5845 bp were identified. The annotation analysis reveals the presence of 5328 genes, encompassing 5186 protein-coding sequences, and 142 RNA genes, including 39 rRNAs, 103 tRNAs, and 5 ncRNAs. The aim of this study was to make a comprehensive genomic exploration that promises to enhance our understanding of the previously understudied and recently documented capabilities of Bacillus paranthracis and to shed light on a potential use of the strain in the industrial production of PC-PLC.

Bacillus cereus cereolysin O induces pyroptosis in an undecapeptide-dependent manner

Bacillus cereus is a clinically significant foodborne pathogen that causes severe gastrointestinal and non-gastrointestinal disease. Cereolysin O (CLO) is a putative virulence factor of B. cereus, and its function remains to be investigated. In this study, we examined the biological activity of CLO from a deep sea B. cereus isolate. CLO was highly toxic to mammalian cells and triggered pyroptosis through NLRP3 inflammasome-mediated caspase 1 and gasdermin D activation. CLO-induced cell death involved ROS accumulation and K+ efflux, and was blocked by serum lipids. CLO bound specifically to cholesterol, and this binding was essential to CLO cytotoxicity. The structural integrity of the three tryptophan residues in the C-terminal undecapeptide was vital for CLO to interact with membrane lipids and cause membrane perforation. Taken together, these results provided new insights into the molecular mechanism of B. cereus CLO-mediated cytotoxicity.

Whole Genome Sequencing Reveals Antimicrobial Resistance and Virulence Genes of Both Pathogenic and Non-Pathogenic B. cereus Group Isolates from Foodstuffs in Thailand

Members of the Bacillus cereus group are spore-forming Gram-positive bacilli that are commonly associated with diarrheal or emetic food poisoning. They are widespread in nature and frequently present in both raw and processed food products. Here, we genetically characterized 24 B. cereus group isolates from foodstuffs. Whole-genome sequencing (WGS) revealed that most of the isolates were closely related to B. cereus sensu stricto (12 isolates), followed by B. pacificus (5 isolates), B. paranthracis (5 isolates), B. tropicus (1 isolate), and "B. bingmayongensis" (1 isolate). The most detected virulence genes were BAS_RS06430, followed by bacillibactin biosynthesis genes (dhbA, dhbB, dhbC, dhbE, and dhbF), genes encoding the three-component non-hemolytic enterotoxin (nheA, nheB, and nheC), a gene encoding an iron-regulated leucine-rich surface protein (ilsA), and a gene encoding a metalloprotease (inhA). Various biofilm-associated genes were found, with high prevalences of tasA and sipW genes (matrix protein-encoding genes); purA, purC, and purL genes (eDNA synthesis genes); lytR and ugd genes (matrix polysaccharide synthesis genes); and abrB, codY, nprR, plcR, sinR, and spo0A genes (biofilm transcription regulator genes). Genes related to fosfomycin and beta-lactam resistance were identified in most of the isolates. We therefore demonstrated that WGS analysis represents a useful tool for rapidly identifying and characterizing B. cereus group strains. Determining the genetic epidemiology, the presence of virulence and antimicrobial resistance genes, and the pathogenic potential of each strain is crucial for improving the risk assessment of foodborne B. cereus group strains.

Neuroinvasive Bacillus cereus Infection in Immunocompromised Hosts: Epidemiologic Investigation of 5 Patients With Acute Myeloid Leukemia

Background

Bacillus cereus is a ubiquitous gram-positive rod-shaped bacterium that can cause sepsis and neuroinvasive disease in patients with acute leukemia or neutropenia.

Methods

A single-center retrospective review was conducted to evaluate patients with acute leukemia, positive blood or cerebrospinal fluid test results for B cereus, and abnormal neuroradiographic findings between January 2018 and October 2022. Infection control practices were observed, environmental samples obtained, a dietary case-control study completed, and whole genome sequencing performed on environmental and clinical Bacillus isolates.

Results

Five patients with B cereus neuroinvasive disease were identified. All patients had acute myeloid leukemia (AML), were receiving induction chemotherapy, and were neutropenic. Neurologic involvement included subarachnoid or intraparenchymal hemorrhage or brain abscess. All patients were treated with ciprofloxacin and survived with limited or no neurologic sequelae. B cereus was identified in 7 of 61 environmental samples and 1 of 19 dietary protein samples-these were unrelated to clinical isolates via sequencing. No point source was identified. Ciprofloxacin was added to the empiric antimicrobial regimen for patients with AML and prolonged or recurrent neutropenic fevers; no new cases were identified in the ensuing year.

Conclusions

B cereus is ubiquitous in the hospital environment, at times leading to clusters with unrelated isolates. Fastidious infection control practices addressing a range of possible exposures are warranted, but their efficacy is unknown and they may not be sufficient to prevent all infections. Thus, including B cereus coverage in empiric regimens for patients with AML and persistent neutropenic fever may limit the morbidity of this pathogen.

Biological control of tomato early blight in Pakistan using local rhizobacteria

BACKGROUND

The biocontrol potential of soil microbes can reduce the extensive use of hazardous synthetic fungicides. This study was designed to find a strain of rhizobacteria indigenous to Pakistan with potential biocontrol against early blight of tomato caused by Alternaria solani and to characterize its biocontrol mechanisms.

RESULTS

Among 88 strains tested for antagonism against A. solani on agar media, S27, Dt10 and 423, identified by 16S rRNA sequencing as strains of Bacillus amyloliquefaciens, B. cereus and Stenotrophomonas rhizophila, respectively, were the most inhibitory. When applied to detached tomato leaflets in Petri dish assays, the strains reduced lesion development by over 30% compared to the control. In greenhouse pot trials, the bacterial strains reduced early blight severity by over 50%. In three field trials, all three strains applied to tomato foliage slowed early blight disease progress and reduced disease severity, with B. amyloliquefaciens S27 reducing the area under the disease progress curve by up to 70%. All three strains showed protease, catalase and oxidase activities in vitro, but none produced β-1,3-glucanase and only B. cereus Dt10 showed slight chitinase activity. In a greenhouse experiment in which the bacteria were applied to tomato foliage prior to pathogen inoculation, bacteria-treated leaves had higher β-1,3-glucanase and chitinase levels than leaves inoculated only with the pathogen, indicating priming induction of response.

CONCLUSION

Three rhizobacteria strains have the potential to control early blight of tomato under Pakistan's growing conditions, with B. amyloliquefaciens S27 being the most promising candidate for commercial development. Antagonism and induction of the priming response may be mechanisms of biocontrol by the bacterial strains. © 2023 Society of Chemical Industry.

Creating a Framework for Treating Autoimmune Gastritis-The Case for Replacing Lost Acid

Autoimmune gastritis (AIG) is characterized by the destruction of gastric parietal cells, resulting in hypochlorhydria and eventual achlorhydria, as oxyntic glands in the corpus are destroyed and become atrophic. The permanent loss of gastric acid has many impacts-both theoretical and documented. The most concerning of these are hypergastrinemia and increased N-nitroso compounds, both of which increase the risk of gastric cancers. While known deficiencies of B12 and iron are often replaced in AIG, acid is not. Moreover, patients with AIG are often prescribed acid suppression for a stomach that is decidedly no longer acidic, worsening the sequelae of gastric atrophy. Betaine hydrochloride (BHCL) is a short-acting acidifying agent, available over the counter in capsule form. Mealtime acid supplementation has an historic basis and could ameliorate many AIG-related gastrointestinal symptoms. Theoretically, acidification could also reduce the potential for hypergastrinemia and the production of N-nitroso compounds, consequently reducing the risk of gastric cancers. Supplemental vitamin C may also help in preventing gastric N-nitroso formation, regardless of the gastric pH. This narrative review describes the functions of gastric acid in gastrointestinal and immune health, documents the effects of hypochlorhydria in AIG, and proposes potential options for safely re-establishing the acid milieu of the stomach for patients with AIG.

Disruption and recovery of outdoor bioaerosols before, during, and after the COVID-19 outbreak at a campus in Central China: pathogen composition, particle size distribution, influencing factors, and exposure risk

Before (2019), during (2020), and after (2021) the COVID-19 outbreak, different response methods and measures were taken on campuses to control the spread of COVID-19 within schools. These response methods may have changed the outdoor bioaerosol characteristics, which may affect staff and student health. Therefore, we analyzed the bacterial concentrations, particle size distribution, microbial populations, exposure risks, and environmental influences of bioaerosols at a campus before, during, and after the COVID-19 outbreak. This study used eight-stage Andersen samplers to collect and analyze culturable bacteria in bioaerosols from various locations, high-throughput sequencing to analyze microbial species, principal component analysis to compare differences in samples, RDA to investigate the effects of environmental factors on bioaerosols, and hazard quotient (HQ) and BugBase to evaluate human health risks. The study findings revealed that average bacterial concentrations before, during, and after COVID-19 were 75 CFU m-3, 136 CFU m-3, and 78 CFU m-3, respectively. Moreover, the average percentage of bacteria attached to PM2.5 was 49.2%, 42.7%, and 29.9%, respectively. High-throughput sequencing revealed that species composition changed significantly during the three years of COVID-19. The proportion of Pantoea and Bacillus increased with the development of COVID-19 and these became the dominant strains after COVID-19, whereas Pseudomonas had the maximum proportion during COVID-19. Both risk assessment and BugBase phenotype prediction results indicated that the potential pathogenic risk was the highest in the outdoor environment of the campus during COVID-19 and that bioaerosol contamination was the most severe compared to the outdoor bioaerosol characteristics of the campus recovered after COVID-19.

Mango Peels as an Industrial By-Product: A Sustainable Source of Compounds with Antioxidant, Enzymatic, and Antimicrobial Activity

Plant waste materials are important sources of bioactive compounds with remarkable health-promoting benefits. In particular, industrial by-products such as mango peels are sustainable sources of bioactive substances, with antioxidant, enzymatic, and antimicrobial activity. Appropriate processing is essential to obtain highly bioactive compounds for further use in generating value-added products for the food industry. The objective of the study was to investigate and compare the biological activity of compounds from fresh and dried mango peels obtained by different conventional methods and unconventional extraction methods using supercritical fluids (SFE). The highest total phenolic content (25.0 mg GAE/g DW) and the total content of eight phenolic compounds (829.92 µg/g DW) determined by LC-MS/MS were detected in dried mango peel extract obtained by the Soxhlet process (SE). SFE gave the highest content of proanthocyanidins (0.4 mg PAC/g DW). The ethanolic ultrasonic process (UAE) provided the highest antioxidant activity of the product (82.4%) using DPPH radical scavenging activity and total protein content (2.95 mg protein/g DW). Overall, the dried mango peels were richer in bioactive compounds (caffeic acid, chlorogenic acid, gallic acid, catechin, and hesperidin/neohesperidin), indicating successful preservation during air drying. Furthermore, outstanding polyphenol oxidase, superoxide dismutase (SOD), and lipase activities were detected in mango peel extracts. This is the first study in which remarkable antibacterial activities against the growth of Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) were evaluated by determining the microbial growth inhibition rate after 12 and 24 h incubation periods for mango peel extracts obtained by different methods. Ethanolic SE and UAE extracts from dried mango peels resulted in the lowest minimum inhibitory concentrations (MIC90) for all bacterial species tested. Mango peels are remarkable waste products that could contribute to the sustainable development of exceptional products with high-added value for various applications, especially as dietary supplements.

Meat and meat products as potential sources of emerging MDR Bacillus cereus: groEL gene sequencing, toxigenic and antimicrobial resistance

BACKGROUND

Bacillus cereus is implicated in severe foodborne infection in humans. This study intended to assess the occurrence, groEL gene sequencing, biofilm production, and resistance profiles of emerged multidrug resistant (MDR) B. cereus in meat and meat product samples. Moreover, this work highlights the virulence and toxigenic genes (hblABCD complex, nheABC complex, cytK, ces, and pc-plc) and antimicrobial resistance genes (bla1, tetA, bla2, tetB, and ermA).

METHODS

Consequently, 200 samples (sausage, minced meat, luncheon, beef meat, and liver; n = 40 for each) were indiscriminately collected from commercial supermarkets in Port Said Province, Egypt, from March to May 2021. Subsequently, food samples were bacteriologically examined. The obtained isolates were tested for groEL gene sequence analysis, antibiotic susceptibility, biofilm production, and PCR screening of toxigenic and resistance genes.

RESULTS

The overall prevalence of B. cereus among the inspected food samples was 21%, where the highest predominance was detected in minced meat (42.5%), followed by beef meat (30%). The phylogenetic analysis of the groEL gene exposed that the examined B. cereus strain disclosed a notable genetic identity with other strains from the USA and China. Moreover, the obtained B. cereus strains revealed β-hemolytic activity, and 88.1% of the recovered strains tested positive for biofilm production. PCR evidenced that the obtained B. cereus strains usually inherited the nhe complex genes (nheA and nheC: 100%, and nheB: 83.3%), followed by cytK (76.2%), hbl complex (hblC and hblD: 59.5%, hblB: 16.6%, and hblA: 11.9%), ces (54.7%), and pc-plc (30.9%) virulence genes. Likewise, 42.9% of the examined B. cereus strains were MDR to six antimicrobial classes and encoded bla1, bla2, ermA, and tetA genes.

CONCLUSION

In summary, this study highlights the presence of MDR B. cereus in meat and meat products, posing a significant public health risk. The contamination by B. cereus is common in minced meat and beef meat. The molecular assay is a reliable fundamental tool for screening emerging MDR B. cereus strains in meat and meat products.

A Novel Prophage-like Insertion Element within yabG Triggers Early Entry into Sporulation in Clostridium botulinum

Sporulation is a finely regulated morphogenetic program important in the ecology and epidemiology of Clostridium botulinum. Exogenous elements disrupting sporulation-associated genes contribute to sporulation regulation and introduce diversity in the generally conserved sporulation programs of endospore formers. We identified a novel prophage-like DNA segment, termed the yin element, inserted within yabG, encoding a sporulation-specific cysteine protease, in an environmental isolate of C. botulinum. Bioinformatic analysis revealed that the genetic structure of the yin element resembles previously reported mobile intervening elements associated with sporulation genes. Within a pure C. botulinum culture, we observed two subpopulations of cells with the yin element either integrated into the yabG locus or excised as a circular DNA molecule. The dynamics between the two observed conformations of the yin element was growth-phase dependent and likely mediated by recombination events. The yin element was not required for sporulation by C. botulinum but triggered an earlier entry into sporulation than in a related isolate lacking this element. So far, the yin element has not been found in any other C. botulinum strains or other endospore-forming species. It remains to be demonstrated what kind of competitive edge it provides for C. botulinum survival and persistence.

Surely you can't B. cereus: Bacillus cereus infection resulting in spontaneous pseudoaneurysm of a nonaccessed arteriovenous graft

Vascular graft infections are a well-described complication of loop arteriovenous grafts (AVGs) placed for hemodialysis access and are reported to occur in 0.5% to 6.0% of AVGs. The most common microorganisms implicated in these infections are the Staphylococcus species. We present a case of a chronically nonaccessed graft rupture caused by an indolent B. cereus colonization, which is usually a foodborne contaminant. The finding of this organism as the causal agent in an AVG infection warrants further research into the potential emergence of the Bacillus species as a contributing factor in the morbidity and mortality resulting from AVG infection.

Pathological changes of highly pathogenic Bacillus cereus on Pelodiscus sinensis

An outbreak of a disease with a high mortality rate occurred in a Chinese Softshell Turtle (Pelodiscus sinensis) farm in Hubei Province. This study isolated a highly pathogenic Bacillus cereus strain (Y271) from diseased P. sinensis. Y271 has β hemolysis, containing both Hemolysin BL (hblA, hblC, and hblD), Non-hemolytic enterotoxin, NHE (nheA, nheB, and nheC), and Enterotoxin FM (entFM) genes. Y271 is highly pathogenic against P. sinensis with an LD50 = 6.80 × 103 CFU/g weight. B. cereus was detected in multiple tissues of the infected P. sinensis. Among them, spleen tissue showed the highest copy number density (1.54 ± 0.12 × 104 copies/mg). Multiple tissues and organs of diseased P. sinensis exhibited significant pathological damage, especially the spleen, liver, kidney, and intestine. It showed obvious tissue structure destruction, lesions, necrosis, red blood cells, and inflammatory cell infiltration. B. cereus proliferating in the spleen, liver, and other tissues was observed. The intestinal microbiota of the diseased P. sinensis was altered, with a greater abundance of Firmicutes, Fusobacterium, and Actinomyces than in the healthy group. Allobaculum, Rothia, Aeromonas, and Clostridium abundance were higher in the diseased group than in the healthy group. The number of unique microbial taxa (472) in the disease group was lower than that of the healthy group (705). Y271 was sensitive to multiple drugs, including florfenicol, enrofloxacin, neomycin, and doxycycline. B. cereus is the etiological agent responsible for the massive death of P. sinensis and reveals its potential risks during P. sinensis cultivation.

Risk factors associated with infection-related mortality of Bacillus cereus bacteremia in hematologic disorders

The mortality risk factors in B. cereus bacteremia in hematologic disorders are still unknown. In this study, patients with B. cereus bacteremia in hematologic disorders were selected in St. lukes international hospital and from electronic databases. A total of 176 patients [median age, 41 years (3-88 years); 99 (56%) males] were included. Of these patients, 141 (80%) had acute leukemia, and 93 (53%) died. Univariate analysis showed that neutropenia, CNS, gastrointestinal, and respiratory infections/symptoms were significantly associated with infection-related death. Meanwhile, glycopeptide use and management with source control were protective factors. Multivariate logistic regression analysis showed that infection-related death was significantly associated with CNS [odds ratio (OR): 3.49, 95% confidence interval (CI) 1.25-9.80], gastrointestinal (OR: 5.22, 95% CI 1.82-8.99), and respiratory infections/symptoms (OR: 8.98, 95% CI 1.62-49.9), as well as glycopeptide use (OR: 0.10, 95% CI 0.03-0.31) and source control (OR: 0.11, 95% CI 0.03-0.37). In conclusion, early glycopeptide administration and source control should be performed upon detection of infections suspicious for B. cereus.

Virulence-related genotypic differences among Bacillus cereus ocular and gastrointestinal isolates and the relationship to endophthalmitis pathogenesis

Background

Bacillus cereus (Bc) can cause self-limiting gastrointestinal infections, but when infecting the eye, can cause rapid and irreversible blindness. This study investigated whether clinical ocular and gastrointestinal Bc isolates differed in terms of virulence-related genotypes and endophthalmitis virulence.

Methods

Twenty-eight Bc ocular, gastrointestinal, and laboratory reference isolates were evaluated. Hemolysis assays were performed to assess potential differences in hemolytic activity. The presence of twenty Bc virulence-related genes was assessed by PCR. A subset of ocular and gastrointestinal isolates differing in PCR positivity for 5 virulence genes was compared to strain ATCC14579 in an experimental murine model of endophthalmitis. At 8 hours post infection, retinal function was evaluated by electroretinography, and intraocular bacterial concentrations were determined by plate counts.

Results

Gastrointestinal Bc isolates were more hemolytic than the Bc ocular isolates and ATCC14579 (p < 0.0001). Bc ocular isolates were more frequently PCR-positive for capK, cytK, hblA, hblC, and plcR compared to the gastrointestinal isolates (p ≤ 0.0002). In the endophthalmitis model, mean A-wave retention did not differ significantly between eyes infected with ATCC14579 and eyes infected with the selected ocular or gastrointestinal isolates (p ≥ 0.3528). Similar results were observed for mean B-wave retention (p ≥ 0.0640). Only one diarrheal isolate showed significantly greater B-wave retention when compared to ATCC14579 (p = 0.0303). No significant differences in mean A-wave (p ≥ 0.1535) or B-wave (p ≥ 0.0727) retention between the selected ocular and gastrointestinal isolates were observed. Intraocular concentrations of ATCC14579 were significantly higher than the selected ocular isolate and 3 of the gastrointestinal isolates (p ≤ 0.0303). Intraocular concentrations of the selected ocular isolate were not significantly different from the gastrointestinal isolates (p ≥ 0.1923).

Conclusions

Among the subset of virulence-related genes assessed, 5 were significantly enriched among the ocular isolates compared to gastrointestinal isolates. While hemolytic activity was higher among gastrointestinal isolates, retinal function retention and intraocular growth was not significantly different between the selected ocular and gastrointestinal isolates. These results suggest that Bc strains causing gastrointestinal infections, while differing from ocular isolates in hemolytic activity and virulence-related gene profile, are similarly virulent in endophthalmitis.

Bacillus cereus: A review of "fried rice syndrome" causative agents

"Fried rice syndrome" originated from the first exposure to a fried rice dish contaminated with Bacillus cereus. This review compiles available data on the prevalence of B. cereus outbreak cases that occurred between 1984 and 2019. The outcome of B. cereus illness varies dramatically depending on the pathogenic strain encounter and the host's immune system. B. cereus causes a self-limiting, diarrheal illness caused by heat-resistant enterotoxin proteins, and an emetic illness caused by the deadly toxin named cereulide. The toxins together with their extrinsic factors are discussed. The possibility of more contamination of B. cereus in protein-rich food has also been shown. Therefore, the aim of this review is to summarize the available data, focusing mainly on B. cereus physiology as the causative agent for "fried rice syndrome." This review emphasizes the prevalence of B. cereus in starchy food contamination and outbreak cases reported, the virulence of both enterotoxins and emetic toxins produced, and the possibility of contaminated in protein-rich food. The impact of emetic or enterotoxin-producing B. cereus on public health cannot be neglected. Thus, it is essential to constantly monitor for B. cereus contamination during food handling and hygiene practices for food product preparation.

Contamination of Plant Foods with Bacillus cereus in a Province and Analysis of Its Traceability

Bacillus cereus is an important zoonotic foodborne conditional pathogen. It is found in vegetables, dairy products, rice, and other foods, thereby greatly endangering human health. Investigations on B. cereus contamination in China primarily focus on raw milk, dairy products, meat, and others, and limited research has been conducted on plant-based foodstuffs. The rapid development of sequencing technology and the application of bioinformatics-related techniques means that analysis based on whole-genome sequencing has become an important tool for the molecular-epidemiology investigation of B. cereus. In this study, we investigated the contamination of B. cereus in six types of commercially available plant foods from eight regions of a province. The molecular epidemiology of the isolated B. cereus was analyzed by whole-genome sequencing. We aimed to provide fundamental data for the surveillance and epidemiology analysis of B. cereus in food products in China. The rapid traceability system of B. cereus established in this study can provide a basis for rapid molecular epidemiology analysis of B. cereus, as well as for the prevention and surveillance of B. cereus. Moreover, it can also be expanded to monitoring and rapid tracing of more foodborne pathogens.

The importance of the PapR7 C-terminus and amide protons in mediating quorum sensing in Bacilluscereus

The opportunistic human pathogen Bacillus cereus controls the expression of key infection-promoting phenotypes using bacterial quorum sensing (QS). QS signal transduction within the species is controlled by an autoinducing peptide, PapR7, and its cognate receptor, PlcR, indicating that the PlcR:PapR interface is a prime target for QS inhibitor development. The C-terminal region of the peptide (PapR7; ADLPFEF) has been successfully employed as a scaffold to develop potent QS modulators. Despite the noted importance of the C-terminal carboxylate and amide protons in crystallographic data, their role in QS activity has yet to be explored. In this study, an N-methyl scan of PapR7 was conducted in conjunction with a C-terminal modification of previously identified B. cereus QS inhibitors. The results indicate that the amide proton at Glu6 and the C-terminal carboxylate are important for effective QS inhibition of the PlcR regulon. Through β-galactosidase and hemolysis assays, a series of QS inhibitors were discovered, including several capable of inhibiting QS with nanomolar potency. These inhibitors, along with the structure-activity data reported, will serve as valuable tools for disrupting the B. cereus QS pathway towards developing novel anti-infective strategies.

Emergence of NDM-1-producing Raoultella ornithinolytica from reservoir water in Northeast Thailand

Background and Aim

Antibiotic resistance is a major global health threat. The increasing prevalence of drug-resistant bacteria poses a serious challenge to the effective treatment of infections in both humans and animals. Water is a major source of human and animal exposure to bacteria, and the presence of drug-resistant bacteria in water could present a severe threat to public health and animal production. This study investigated the presence of drug-resistant bacteria in Lam Pao Dam (LPD) water in Kalasin, Thailand.

Materials and Methods

Ampicillin-resistant strains were obtained from LPD water and identified using 16s rDNA sequencing. Antibiotic resistance genes were detected by polymerase chain reaction using specific primers. The presence of antibiotic-resistant bacteria was evaluated using 16s amplicon analysis. The minimum inhibitory concentration (MIC) of Raoultella ornithinolytica strains against antibiotics was determined.

Results

A total of 12 R. ornithinolytica, 4 Bacillus cereus, and 4 Enterococcus faecalis isolates were resistant to ampicillin. Almost all R. ornithinolytica strains harbored blaSHV and blaOXA genes, and two strains also harbored the blaNDM-1 gene. All four E. faecalis strains harbored the blaIMP gene. The most abundant species in the LPD sample was Exiguobacterium indicum, followed by E. faecalis and R. ornithinolytica. The MICs of 10 R. ornithinolytica strains against five antibiotics revealed that all strains were resistant to ampicillin but susceptible to meropenem, doripenem, ertapenem, and imipenem.

Conclusion

These findings suggest a high prevalence of drug-resistant bacteria in LPD water. This is a cause for concern, as it could spread antibiotic-resistant infections in the community.

Coinfection of Malaria and Bacterial Pathogens among Acute Febrile Patients in Selected Clinics in Ghana

Malaria remains the leading cause of acute febrile illness (AFI) in Africa despite successful control measures and programs. Acute febrile illnesses can be misdiagnosed as malaria as a result of the overlapping spectrum of nonspecific symptoms or may not be pursued because of limited diagnostic capabilities. This study investigated potential etiologies of AFIs in Ghana and determined the relationship between coinfection between malaria and Q fever, leptospirosis, and culturable bacteria in febrile patients. Participants were enrolled between July 2015 and December 2019 from four Ghanaian military treatment facilities. Of the 399 febrile participants, 222 (55.6%) males and 177 (44.6%) females were enrolled. Malaria was diagnosed in 275 (68.9%) participants. Malaria coinfection occurred with leptospirosis, Q fever, and blood-cultured bacteria in 11/206 (5.3%), 24/206 (11.7%), and 6/164 (3.7%) participants, respectively. Among the 124 malaria-negative samples, the positivity rates were 4.1% (3/74), 8.1% (6/74), and 3.6% (2/56) for leptospirosis, Q fever, and bacterial pathogens isolated from blood culture, respectively. The majority of documented clinical signs and symptoms were not significantly associated with specific diseases. Approximately 10% of malaria-positive participants also had evidence suggesting the presence of a bacterial coinfection. Therefore, even in the case of a positive malaria test, other pathogens contributing to febrile illness should be considered. Understanding the frequency of malaria coinfection and other etiological agents responsible for AFIs will improve diagnosis and treatment and better inform public health knowledge gaps in Ghana.

Endospore production of Bacillus spp. for industrial use

The increased occurrence of antibiotic resistance and the harmful use of pesticides are a major problem of modern times. A ban on the use of antibiotics as growth promoters in animal breeding has put a focus on the probiotics market. Probiotic food supplements are versatile and show promising results in animal and human nutrition. Chemical pesticides can be substituted by biopesticides, which are very effective against various pests in plants due to increased research. What these fields have in common is the use of spore-forming bacteria. The endospore-forming Bacillus spp. belonging to this group offer an effective solution to the aforementioned problems. Therefore, the biotechnological production of sufficient qualities of such endospores has become an innovative and financially viable field of research. In this review, the production of different Bacillus spp. endospores will be reviewed. For this purpose, the media compositions, cultivation conditions and bioprocess optimization methods of the last 20 years are presented and reflected.

Advancing understanding of microbial biofilms through machine learning-powered studies

Microbial biofilms are prevalent in various environments and pose significant challenges to food safety and public health. The biofilms formed by pathogens can cause food spoilage, foodborne illness, and infectious diseases, which are difficult to treat due to their enhanced antimicrobial resistance. While the composition and development of biofilms have been widely studied, their profound impact on food, the food industry, and public health has not been sufficiently recapitulated. This review aims to provide a comprehensive overview of microbial biofilms in the food industry and their implication on public health. It highlights the existence of biofilms along the food-producing chains and the underlying mechanisms of biofilm-associated diseases. Furthermore, this review thoroughly summarizes the enhanced understanding of microbial biofilms achieved through machine learning approaches in biofilm research. By consolidating existing knowledge, this review intends to facilitate developing effective strategies to combat biofilm-associated infections in both the food industry and public health.

Rare case of bacteremia due to Lysinibacillus sphaericus in a person living with HIV

Lysinibacillus sphaericus, as an insect pathogen, is a ubiquitous Gram-positive bacterium present in the environment. It is often considered to be contaminating bacteria. L. sphaericus has been reported to cause infectious diseases in humans relatively rarely. We report a rare case of bacteremia due to L. sphaericus in a person living with HIV, which is also the first reported case of bacteremia caused by L. sphaericus in China. L. sphaericus easily causes infection in immunocompromised individuals. We found that L. sphaericus and Lysinibacillus fusiformis could not be distinguished by their 16S ribosomal RNA gene sequence. We performed a genome-wide analysis of the isolated strains of this case and predicted the virulence factors. Finally, L. sphaericus was confirmed. According to antimicrobial susceptibility test, the strain was found to be sensitive to levofloxacin and vancomycin but resistant to penicillin. Greater attention to L. sphaericus infection should be paid and immunocompromised populations should be protected from L. sphaericus infection.

Sterilizing orthodontic appliances: A systematic review and meta-analysis on the available methods

Infection control is essential to protect both the doctor and the patient by preventing the spread of infectious diseases. There is no exception in the field of dentistry, particularly in orthodontics, where numerous appliances are used for a variety of functions and also because the mouth cavity has the highest concentration of bacteria of any body part. Through this systematic review, we aimed to assess the various methods of sterilization employed in an orthodontic setting. Using relevant keywords, reference searches, and citation searches, the databases such as PubMed, MEDLINE, Web of Science, Cochrane, and Scopus were all searched; a total of 206 documents were found, of which 113 were initially selected. The remaining 23 distinct papers were initially made available after 90 publications that were identical to or similar to one another were eliminated. The final selection was made from eight documents that met all inclusion and exclusion requirements. The existing methods of sterilization were found to be competent in dealing with the microorganisms found in a typical orthodontic setting. The chemical method of sterilization was the norm in most of the studies that we assessed, with glutaraldehyde and peracetic acid (PAA) being the most commonly employed compounds for disinfection. PROSPERO Registration Number: CRD42022380831.

The quorum-sensing peptidic inhibitor rescues host immune system eradication: A novel infectivity mechanism

Subverting the host immune system is a major task for any given pathogen to assure its survival and proliferation. For the opportunistic human pathogen Bacillus cereus (Bc), immune evasion enables the establishment of potent infections. In various species of the Bc group, the pleiotropic regulator PlcR and its cognate cell-cell signaling peptide PapR7 regulate virulence gene expression in response to fluctuations in population density, i.e., a quorum-sensing (QS) system. However, how QS exerts its effects during infections and whether PlcR confers the immune evading ability remain unclear. Herein, we report how interception of the QS communication in Bc obliterates the ability to affect the host immune system. Here, we designed a peptide-based QS inhibitor that suppresses PlcR-dependent virulence factor expression and attenuates Bc infectivity in mouse models. We demonstrate that the QS peptidic inhibitor blocks host immune system-mediated eradication by reducing the expression of PlcR-regulated major toxins similarly to the profile that was observed for isogenic strains. Our findings provide evidence that Bc infectivity is regulated by QS circuit-mediated destruction of host immunity, thus reveal a interesting strategy to limit Bc virulence and enhance host defense. This peptidic quorum-quenching agent constitutes a readily accessible chemical tool for studying how other pathogen QS systems modulate host immunity and forms a basis for development of anti-infective therapeutics.

Genomic and Phylogenetic Analysis of Bacillus cereus Biovar anthracis Isolated from Archival Bone Samples Reveals Earlier Natural History of the Pathogen

(1) Background: Bacillus cereus biovar anthracis (Bcbva) was the causative agent of an anthrax-like fatal disease among wild chimpanzees in 2001 in Côte d'Ivoire. Before this, there had not been any description of an anthrax-like disease caused by typically avirulent Bacillus cereus. Genetic analysis found that B. cereus had acquired two anthrax-like plasmids, one a pXO1-like toxin producing plasmid and the other a pXO2-like plasmid encoding capsule. Bcbva caused animal fatalities in Cameroon, Democratic Republic of Congo, and the Central African Republic between 2004 and 2012. (2) Methods: The pathogen had acquired plasmids in the wild and that was discovered as the cause of widespread animal fatalities in the early 2000s. Primate bones had been shipped out of the endemic zone for anthropological studies prior to the realized danger of contamination with Bcbva. Spores were isolated from the bone fragments and positively identified as Bcbva. Strains were characterized by classical microbiological methods and qPCR. Four new Bcbva isolates were whole-genome sequenced. Chromosomal and plasmid phylogenomic analysis was performed to provide temporal and spatial context to these new strains and previously sequenced Bcbva. Tau and principal component analyses were utilized to identify genetic and spatial case patterns in the Taï National Park anthrax zone. (3) Results: Preliminary studies positively identified Bcbva presence in several archival bone fragments. The animals in question died between 1994 and 2010. Previously, the earliest archival strains of Bcbva were identified in 1996. Though the pathogen has a homogeneous genome, spatial analyses of a subset of mappable isolates from Taï National Park revealed strains found closer together were generally more similar, with strains from chimpanzees and duikers having the widest distribution. Ancestral strains were located mostly in the west of the park and had lower spatial clustering compared to more recent isolates, indicating a local increase in genetic diversity of Bcbva in the park over space and time. Global clustering analysis indicates patterns of genetic diversity and distance are shared between the ancestral and more recently isolated type strains. (4) Conclusions: Our strains have the potential to unveil historical genomic information not available elsewhere. This information sheds light on the evolution and emergence of a dangerous anthrax-causing pathogen.

Bacteria exposed to antiviral drugs develop antibiotic cross-resistance and unique resistance profiles

Antiviral drugs are used globally as treatment and prophylaxis for long-term and acute viral infections. Even though antivirals also have been shown to have off-target effects on bacterial growth, the potential contributions of antivirals to antimicrobial resistance remains unknown. Herein we explored the ability of different classes of antiviral drugs to induce antimicrobial resistance. Our results establish the previously unrecognized capacity of antivirals to broadly alter the phenotypic antimicrobial resistance profiles of both gram-negative and gram-positive bacteria Escherichia coli and Bacillus cereus. Bacteria exposed to antivirals including zidovudine, dolutegravir and raltegravir developed cross-resistance to commonly used antibiotics including trimethoprim, tetracycline, clarithromycin, erythromycin, and amoxicillin. Whole genome sequencing of antiviral-resistant E. coli isolates revealed numerous unique single base pair mutations, as well as multi-base pair insertions and deletions, in genes with known and suspected roles in antimicrobial resistance including those coding for multidrug efflux pumps, carbohydrate transport, and cellular metabolism. The observed phenotypic changes coupled with genotypic results indicate that bacteria exposed to antiviral drugs with antibacterial properties in vitro can develop multiple resistance mutations that confer cross-resistance to antibiotics. Our findings underscore the potential contribution of wide scale usage of antiviral drugs to the development and spread of antimicrobial resistance in humans and the environment.

Agonistic antibacterial potential of Loigolactobacillus coryniformis BCH-4 metabolites against selected human pathogenic bacteria: An in vitro and in silico approach

Lactic acid bacteria are known to produce numerous antibacterial metabolites that are active against various pathogenic microbes. In this study, bioactive metabolites from the cell free supernatant of Loigolactobacillus coryniformis BCH-4 were obtained by liquid-liquid extraction, using ethyl acetate, followed by fractionation, using silica gel column chromatography. The collected F23 fraction effectively inhibited the growth of pathogenic bacteria (Escherichia coli, Bacillus cereus, and Staphylococcus aureus) by observing the minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC). The evaluated values of MIC were 15.6 ± 0.34, 3.9 ± 0.59, and 31.2 ± 0.67 μg/mL and MBC were 15.6 ± 0.98, 7.8 ± 0.45, and 62.5 ± 0.23 μg/mL respectively, against the above-mentioned pathogenic bacteria. The concentration of F23 fraction was varying from 1000 to 1.9 μg/mL. Furthermore, the fraction also exhibited sustainable biofilm inhibition. Using the Electrospray Ionization Mass Spectrometry (ESI-MS/MS), the metabolites present in the bioactive fraction (F23), were identified as phthalic acid, myristic acid, mangiferin, 16-hydroxylpalmatic acid, apigenin, and oleandomycin. By using in silico approach, docking analysis showed good interaction of identified metabolites and receptor proteins of pathogenic bacteria. The present study suggested Loigolactobacillus coryniformis BCH-4, as a promising source of natural bioactive metabolites which may receive great benefit as potential sources of drugs in the pharmacological sector.

Metaproteomic Analysis of Nasopharyngeal Swab Samples to Identify Microbial Peptides in COVID-19 Patients

During the COVID-19 pandemic, impaired immunity and medical interventions resulted in cases of secondary infections. The clinical difficulties and dangers associated with secondary infections in patients necessitate the exploration of their microbiome. Metaproteomics is a powerful approach to study the taxonomic composition and functional status of the microbiome under study. In this study, the mass spectrometry (MS)-based data of nasopharyngeal swab samples from COVID-19 patients was used to investigate the metaproteome. We have established a robust bioinformatics workflow within the Galaxy platform, which includes (a) generation of a tailored database of the common respiratory tract pathogens, (b) database search using multiple search algorithms, and (c) verification of the detected microbial peptides. The microbial peptides detected in this study, belong to several opportunistic pathogens such as Streptococcus pneumoniae, Klebsiella pneumoniae, Rhizopus microsporus, and Syncephalastrum racemosum. Microbial proteins with a role in stress response, gene expression, and DNA repair were found to be upregulated in severe patients compared to negative patients. Using parallel reaction monitoring (PRM), we confirmed some of the microbial peptides in fresh clinical samples. MS-based clinical metaproteomics can serve as a powerful tool for detection and characterization of potential pathogens, which can significantly impact the diagnosis and treatment of patients.

Core genome multilocus sequence typing scheme for Bacillus cereus group bacteria

Core genome multilocus sequence typing (cgMLST) employs a strategy where the set of orthologous genes common to all members of a group of organisms are used for phylogenetic analysis of the group members. The Bacillus cereus group consists of species with pathogenicity towards insect species as well as warm-blooded animals including humans. While B. cereus is an opportunistic pathogen linked to a range of human disease conditions, including emesis and diarrhoea, Bacillus thuringiensis is an entomopathogenic species with toxicity toward insect larvae, and therefore used as a biological pesticide worldwide. Bacillus anthracis is a classical obligate pathogen causing anthrax, an acute lethal condition in herbivores as well as humans, and which is endemic in many parts of the world. The group also includes a range of additional species, and B. cereus group bacteria have been subject to analysis with a wide variety of phylogenetic typing systems. Here we present, based on analyses of 173 complete genomes from B. cereus group species available in public databases, the identification of a set of 1568 core genes which were used to create a core genome multilocus typing scheme for the group which is implemented in the PubMLST system as an open online database freely available to the community. The new cgMLST system provides unprecedented resolution over existing phylogenetic analysis schemes covering the B. cereus group.

Retrospective surveillance of viable Bacillus cereus group contaminations in commercial food and feed vitamin B2 products sold on the Belgian market using whole-genome sequencing

Bacillus cereus is a spore-forming bacterium that occurs as a contaminant in food and feed, occasionally resulting in food poisoning through the production of various toxins. In this study, we retrospectively characterized viable B. cereus sensu lato (s.l.) isolates originating from commercial vitamin B₂ feed and food additives collected between 2016 and 2022 by the Belgian Federal Agency for the Safety of the Food Chain from products sold on the Belgian market. In total, 75 collected product samples were cultured on a general medium and, in case of bacterial growth, two isolates per product sample were collected and characterized using whole-genome sequencing (WGS) and subsequently characterized in terms of sequence type (ST), virulence gene profile, antimicrobial resistance (AMR) gene profile, plasmid content, and phylogenomic relationships. Viable B. cereus was identified in 18 of the 75 (24%) tested products, resulting in 36 WGS datasets, which were classified into eleven different STs, with ST165 (n = 10) and ST32 (n = 8) being the most common. All isolates carried multiple genes encoding virulence factors, including cytotoxin K-2 (52.78%) and cereulide (22.22%). Most isolates were predicted to be resistant to beta-lactam antibiotics (100%) and fosfomycin (88.89%), and a subset was predicted to be resistant to streptothricin (30.56%). Phylogenomic analysis revealed that some isolates obtained from different products were closely related or even identical indicating a likely common origin, whereas for some products the two isolates obtained did not show any close relationship to each other or other isolates found in other products. This study reveals that potentially pathogenic and drug-resistant B. cereus s.l. can be present in food and feed vitamin B₂ additives that are commercially available, and that more research is warranted to assess whether their presence in these types of products poses a threat to consumers.

Hydrophilic sulfurized nanoscale zero-valent iron for enhancing in situ biocatalytic denitrification: Mechanisms and long-term column studies

The aim of this study was to investigate the effects of hydrophilic sulfur-modified nanoscale zero-valent iron (S-nZVI) as a biocatalyst for denitrification. We found that the denitrifying bacteria Cupriavidus necator (C. necator) promoted Fe corrosion during biocatalytic denitrification, reducing surface passivation and sulfur species leaching from S-nZVI. As a result, S-nZVI exhibited a higher synergistic factor (f_syn = 2.43) for biocatalytic NO₃^- removal than nanoscale zero-valent iron (nZVI, f_syn = 0.65) at an initial nitrate concentration of 25 mg L^-1-N. Based on kinetic profiles, SO₄^2- was the preferred electron acceptor over NO₃^- when using C. necator and S-nZVI for biocatalytic denitrification. Up-flow column experiments demonstrated that biocatalytic denitrification using S-nZVI achieved a total nitrogen removal capacity of up to 2004 mg L^-1 for 127 d. Notably, microbiome taxonomic profiling showed that the addition of S-nZVI to the groundwater promoted the growth of Geobacter, Desulfosporosinus, Streptomyces, and Simplicispira spp in the column experiments. Most of those microbes can reduce sulfate, promote denitrification, and match the batch kinetic profile obtained using C. necator. Our results not only discover the great potential of S-nZVI as a biocatalyst for enhancing denitrification via microbial activation but also provide a deep understanding of the complicated abiotic-biotic interaction.

Development of an Online Genome Sequence Comparison Resource for Bacillus cereus sensu lato Strains Using the Efficient Composition Vector Method

An automated method was developed for differentiating closely related B. cereus sensu lato (s.l.) species, especially biopesticide Bacillus thuringiensis, from other human pathogens, B. anthracis and B. cereus sensu stricto (s.s.). In the current research, four typing methods were initially compared, including multi-locus sequence typing (MLST), single-copy core genes phylogenetic analysis (SCCGPA), dispensable genes content pattern analysis (DGCPA) and composition vector tree (CVTree), to analyze the genomic variability of 23 B. thuringiensis strains from aizawai, kurstaki, israelensis, thuringiensis and morrisoni serovars. The CVTree method was the best option to be used for typing B. thuringiensis strains since it proved to be the fastest method, whilst giving high-resolution data about the strains. In addition, CVTree agrees well with ANI-based method, revealing the relationship between B. thuringiensis and other B. cereus s.l. species. Based on these data, an online genome sequence comparison resource was built for Bacillus strains called the Bacillus Typing Bioinformatics Database to facilitate strain identification and characterization.

Pathogenicity and Genomic Characterization of a Novel Genospecies, Bacillus shihchuchen, of the Bacillus cereus Group Isolated from Chinese Softshell Turtle (Pelodiscus sinensis)

The Chinese softshell turtle (CST; Pelodiscus sinensis) is a freshwater aquaculture species of substantial economic importance that is commercially farmed across Asia, particularly in Taiwan. Although diseases caused by the Bacillus cereus group (Bcg) pose a major threat to commercial CST farming systems, information regarding its pathogenicity and genome remains limited. Here, we investigated the pathogenicity of Bcg strains isolated in a previous study and performed whole-genome sequencing. Pathogenicity analysis indicated that QF108-045 isolated from CSTs caused the highest mortality rate, and whole-genome sequencing revealed that it was an independent group distinct from other known Bcg genospecies. The average nucleotide identity compared to other known Bcg genospecies was below 95%, suggesting that QF108-045 belongs to a new genospecies, which we named Bacillus shihchuchen. Furthermore, genes annotation revealed the presence of anthrax toxins, such as edema factor and protective antigen, in QF108-045. Therefore, the biovar anthracis was assigned, and the full name of QF108-045 was Bacillus shihchuchen biovar anthracis. In addition to possessing multiple drug-resistant genes, QF108-045 demonstrated resistance to various types of antibiotics, including penicillins (amoxicillin and ampicillin), cephalosporins (ceftifour, cephalexin, and cephazolin), and polypeptides, such as vancomycin.

Lonicera japonica Thunb. as a promising antibacterial agent for Bacillus cereus ATCC14579 based on network pharmacology, metabolomics, and in vitro experiments

Lonicera japonica Thunb. has attracted much attention for its treatment of bacterial and viral infectious diseases, while its active ingredients and potential mechanisms of action have not been fully elucidated. Here, we combined metabolomics, and network pharmacology to explore the molecular mechanism of Bacillus cereus ATCC14579 inhibition by Lonicera japonica Thunb. In vitro inhibition experiments showed that the Lonicera japonica Thunb.'s water extracts, ethanolic extract, luteolin, quercetin, and kaempferol strongly inhibited Bacillus cereus ATCC14579. In contrast, chlorogenic acid and macranthoidin B had no inhibitory effect on Bacillus cereus ATCC14579. Meanwhile, the minimum inhibitory concentrations of luteolin, quercetin, and kaempferol against Bacillus cereus ATCC14579 were 15.625 μg mL-1, 31.25 μg mL-1, and 15.625 μg mL-1. Based on the previous experimental basis, the metabolomic analysis showed the presence of 16 active ingredients in Lonicera japonica Thunb.'s water extracts and ethanol extracts, with differences in the luteolin, quercetin, and kaempferol contents between the water extracts and ethanol extracts. Network pharmacology studies indicated that fabZ, tig, glmU, secA, deoD, nagB, pgi, rpmB, recA, and upp were potential key targets. Active ingredients of Lonicera japonica Thunb. may exert their inhibitory effects by inhibiting ribosome assembly, the peptidoglycan biosynthesis process, and the phospholipid biosynthesis process of Bacillus cereus ATCC14579. An alkaline phosphatase activity assay, peptidoglycan concentration assay, and protein concentration assay showed that luteolin, quercetin, and kaempferol disrupted the Bacillus cereus ATCC14579 cell wall and cell membrane integrity. Transmission electron microscopy results showed significant changes in the morphology and ultrastructure of the cell wall and cell membrane of Bacillus cereus ATCC14579, further confirming the disruption of the cell wall and cell membrane integrity of Bacillus cereus ATCC14579 by luteolin, quercetin, and kaempferol. In conclusion, Lonicera japonica Thunb. can be used as a potential antibacterial agent for Bacillus cereus ATCC14579, which may exert its antibacterial activity by destroying the integrity of the cell wall and membrane.

Chemical Composition of the Cinnamomum malabatrum Leaf Essential Oil and Analysis of Its Antioxidant, Enzyme Inhibitory and Antibacterial Activities

Cinnamomum species are a group of plants belonging to the Lauraceae family. These plants are predominantly used as spices in various food preparations and other culinary purposes. Furthermore, these plants are attributed to having cosmetic and pharmacological potential. Cinnamomum malabatrum (Burm. f.) J. Presl is an underexplored plant in the Cinnamomum genus. The present study evaluated the chemical composition by a GC-MS analysis and antioxidant properties of the essential oil from C. malabatrum (CMEO). Further, the pharmacological effects were determined as radical quenching, enzyme inhibition and antibacterial activity. The results of the GC-MS analysis indicated the presence of 38.26 % of linalool and 12.43% of caryophyllene in the essential oil. Furthermore, the benzyl benzoate (9.60%), eugenol (8.75%), cinnamaldehyde (7.01%) and humulene (5.32%) were also present in the essential oil. The antioxidant activity was indicated by radical quenching properties, ferric-reducing potential and lipid peroxidation inhibition ex vivo. Further, the enzyme-inhibitory potential was confirmed against the enzymes involved in diabetes and diabetic complications. The results also indicated the antibacterial activity of these essential oils against different Gram-positive and Gram-negative bacteria. The disc diffusion method and minimum inhibitory concentration analysis revealed a higher antibacterial potential for C. malabatrum essential oil. Overall, the results identified the predominant chemical compounds of C. malabatrum essential oil and its biological and pharmacological effects.

Bacillus cereus in the Artisanal Cheese Production Chain in Southwestern Mexico

BACKGROUND

Bacillus cereus is associated with milk, dairy product, and dairy farm contamination. The aim of this study was to characterize strains of B. cereus in the small-scale artisanal cheese production chain in southwestern Mexico.

METHODS

130 samples were collected. B. cereus isolation was performed on Mannitol Egg Yolk Polymyxin (MYP) agar. Genotyping, enterotoxigenic profile, and determination of genes involved in the formation of B. cereus biofilm were performed by PCR. An antimicrobial susceptibility test was made by broth microdilution assay. The phylogenetic analysis was performed by amplification and sequencing of 16s rRNA.

RESULTS

B. cereus sensu lato was isolated and molecularly identified in 16 samples and B. cereus sensu stricto (B. cereus) was the most frequently isolated and identified species (81.25%). Of all the isolated B. cereus sensu lato strains, 93.75% presented at least one gene for some diarrheagenic toxins, 87.5% formed biofilms, and 18.75% were amylolytic. All B. cereus sensu lato strains were resistant to beta-lactams and folate inhibitors. A close phylogenetic relationship between isolates was found between the cheese isolates and the air isolates.

CONCLUSIONS

Strains of B. cereus sensu lato were found in small-scale artisanal cheeses on a farm in southwestern Mexico.