Bacillus cereus infection: 57 case patients and a literature review

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.

Biosynthesis Optimization of Antibacterial-Magnetic Iron Oxide Nanoparticles from Bacillus megaterium

The occurrence of antibiotic resistance on common bacterial agents and the need to use new generations of antibiotics have led to the use of various strategies for production. Taking inspiration from nature, using bio-imitation patterns, in addition to the low cost of production, is advantageous and highly accurate. In this research, we were able to control the temperature, shake, and synthesis time of the synthesis conditions of Bacillus megaterium bacteria as a model for the synthesis of magnetic iron nanoparticles and optimize the ratio of reducing salt to bacterial regenerating agents as well as the concentration of salt to create iron oxide nanoparticles with more favorable properties and produced with more antibacterial properties. Bacterial growth was investigated by changing the incubation times of pre-culture and overnight culture in the range of the logarithmic phase. The synthesis time, salt ratio, and concentration were optimized to achieve the size, charge, colloidal stability, and magnetic and antibacterial properties of nanoparticles. The amount of the effective substance produced by the bacteria was selected by measuring the amount of the active substance synthesized using the free radical reduction (DPPH) method. With the help of DPPH, the duration of the synthesis was determined to be one week. Characterizations such as UV-vis spectroscopy, FTIR, FESEM, X-ray, and scattering optical dynamics were performed and showed that the nanoparticles synthesized with a salt concentration of 80 mM and a bacterial suspension to salt ratio of 2:1 are smaller in size and have a light scattering index, a PDI index close to 0.1, and a greater amount of reducing salt used in the reaction during one week compared to other samples. Moreover, they had more antibacterial properties than the concentration of 100 mM. As a result, better characteristics and more antibacterial properties than common antibiotics were created on E. coli and Bacillus cereus.

Causal associations between human gut microbiota and osteomyelitis: a Mendelian randomization study

Background

Recent studies have emphasized the role of gut microbiota in the onset and progression of osteomyelitis. However, the exact types of gut microbiota and their mechanisms of action remain unclear. Additionally, there is a lack of theoretical support for treatments that improve osteomyelitis by altering the gut microbiota.

Methods

In our study, we utilized the largest genome-wide association study (GWAS) meta-analysis to date from the MiBioGen consortium, involving 13,400 participants. The GWAS data for osteomyelitis were sourced from the UK Biobank, which included 4,836 osteomyelitis cases and 486,484 controls. We employed a two-sample Mendelian randomization framework for a detailed investigation into the causal relationship between gut microbiota and osteomyelitis. Our methods included inverse variance weighting, MR-Egger, weighted median, and weighted mode approaches. Additionally, we applied Cochran's Q statistic to assess the heterogeneity of the instrumental variable.

Results

At the class level, Bacilli and Bacteroidia were positively correlated with the risk of osteomyelitis. At the order level, only Bacteroidales showed a positive association with osteomyelitis. At the genus level, an increased abundance of Butyricimonas, Coprococcus3, and Tyzzerella3 was positively associated with the risk of osteomyelitis, whereas Lachnospira was negatively associated. Sensitivity analyses showed no evidence of heterogeneity or pleiotropy.

Conclusion

This study reveals that classes Bacilli and Bacteroidia, order Bacteroidales, and genera Butyricimonas, Coprococcus3, and Tyzzerella3 are implicated in increasing the risk of osteomyelitis, while the genus Lachnospira is associated with a reduced risk. Future investigations are warranted to elucidate the precise mechanisms through which these specific bacterial groups influence the pathophysiology of osteomyelitis.

Persistent Bacillus cereus Bacteremia in an Immunocompetent Patient With a History of Polysubstance Abuse

Extraintestinal infections are rare with Bacillus cereus and include endocarditis, pneumonia, and meningoencephalitis. It has been primarily reported in immunosuppressed individuals with hematological malignancies and rarely in people who inject drugs (PWIDs). Herein, we report the case of a healthy adult woman with no underlying conditions except for injection drug use who presented with signs of meningitis. A 40-year-old female intravenous (IV) drug addict presented to the hospital with a chief complaint of severe headache. She had a fever of 38 °C, and her neurological examination was unremarkable. Laboratory results were significant for a white blood cell (WBC) count of 20.0 × 10⁹/L (reference range: 4.5 to 11.0 × 10⁹/L) and urine toxicology that was positive for amphetamines and cocaine. A lumbar puncture showed a total of 1,736 nucleated cells/µL, 88% neutrophils, a glucose level of 73 mg/dL, and a significantly elevated protein level of 155 mg/dL. B. cereus grew in blood cultures and cerebrospinal fluid (CSF) cultures. Once the growth of B. cereus was identified in the CSF, intravenous vancomycin was started. After leaving against medical advice (AMA), the patient presented again to the hospital, and a lumbar puncture was repeated. Cerebrospinal fluid showed total nucleated cells of 13 cells/µL, but the patient remained bacteremic. An echocardiogram, computerized tomography (CT) of the abdomen and pelvis, and tagged white blood cell scan could not identify a source for the bacteremia. Despite receiving two weeks of IV vancomycin, her blood cultures remained consistently positive for B. cereus without identifying a clear source of infection. Although B. cereus rarely affects the central nervous system, there have been a few cases where immunosuppression has been linked to the infection. We report an unusual case of a patient who continued to be bacteremic despite a thorough search for a source of B. cereus infection and IV vancomycin treatment. As a result, we raise the possibility of addictive behavior due to the patient's pattern of leaving the hospital against medical advice and returning with recurrent bacteremia. A thorough history and careful search for a source of infection are required when B. cereus grows persistently in blood cultures.

A Case of Persistent Bacillus cereus Bacteremia Responding to a Combination of Vancomycin and Gentamicin

A 56-year-old woman with a history of connective tissue disease developed fever, and Bacillus cereus (B. cereus) was detected in blood cultures. Therefore, treatment with vancomycin (VCM) was initiated. Since her blood cultures persistently detected B. cereus despite peripheral intravenous catheter replacement and VCM treatment, concomitant treatment with gentamicin (GM) was started. Blood cultures then became negative. Persistent B. cereus bacteremia responded to combination therapy with VCM and GM. This combination therapy may increase the risk of developing renal dysfunction, but the risk can be mitigated by appropriate therapeutic drug monitoring (TDM) and dose adjustments to achieve successful treatment.

A Peek into the Bacterial Microbiome of the Eurasian Red Squirrel (Sciurus vulgaris)

Sciurus vulgaris (the Eurasian red squirrel) is native to Europe and Asia, but due to habitat destruction or fragmentation, interspecific competition, and infectious diseases, especially in European island areas the species finds itself at the brink of extinction. The repopulation of such bare habitats requires healthy squirrel specimens, either translocated from other wild habitats or reintroduced to the wilderness following captive breeding. Captivity, nonetheless, has shown an immense capacity to reshape the structure of wild species’ microbiota, adapting it to the less diverse diet and fewer environmental challenges. Therefore, assessing the differences between “wild” and “captive” microbiota in this species could elucidate if special living conditions are needed in order to augment the survival rate of specimens reintroduced into the wild. Furthermore, the microflora profile of the normal flora of healthy red squirrels raised in captivity could support clinicians in addressing infectious diseases episodes and also raise awareness on the zoonotic risk. Hence, this study aimed at documenting the bacterial species carried by S. vulgaris, disclosing overall similarities and variability patterns of the microbiota identified in individuals from two different living environments. We anticipated that the bacterial community would be less diverse in individuals raised in captivity, owing to their restrictive diet and to unchanging conditions in the enclosure. We also hypothesized that there would be a higher prevalence of zoonotic microorganisms in the captive animals, due to the proximity of humans and of other domestic species. To test this, samples (n = 100) were taken from five body regions of 20 red squirrels, both free-ranging and bred in captivity, processed by classical microbiology techniques, and further identified by biochemical assay (VITEK®2 Compact System). A relatively poor bacterial community, comprising 62 bacterial strains belonging to 18 species and 8 different genera, was identified. Most of these microorganisms were reported for the first time in S. vulgaris. With no discrimination between living environments, the highest prevalence (p < 0.001), was registered in Staphylococcus sciuri (60%; 12/20), followed by Escherichia coli (45%; 9/20) and Bacillus cereus (35%; 7/20). The results suggest unremarkable differences in diversity and richness of the resident aerobic microbiota of S. vulgaris, in relation to the living environment.

Comparative analysis of Bacillus cereus group isolates' resistance using disk diffusion and broth microdilution and the correlation between antimicrobial resistance phenotypes and genotypes

Bacillus cereus group isolates (n = 85) were screened for phenotypic resistance to 18 antibiotics using broth microdilution and CLSI M45 Bacillus spp. breakpoints. The susceptibility to 9 out of 18 antibiotics was tested also using disk diffusion method and M100 Staphylococcus spp. breakpoints. Overall, a high prevalence of susceptibility to clinically relevant antibiotics was identified using broth microdilution. For most tested antibiotics, a poor correlation was found between zones of inhibition and minimum inhibitory concentrations. Using the broth microdilution results as a reference for comparison, we identified high error rates and low categorical agreement between results produced using disk diffusion and broth microdilution for the seven tested antibiotics with defined breakpoints. This suggests that disk diffusion should be avoided for AST of B. cereus group isolates. Further, we detected antimicrobial resistance genes with ARIBA and ABRIcate to calculate the sensitivity and specificity for predicting phenotypic resistance determined using broth microdilution based on the presence of detected antimicrobial resistance genes (ARGs). ARGs with poor sensitivity and high specificity included rph (rifampicin, 0%, 93%), mph (erythromycin, 0%, 99%), bla1 (penicillin, 29%, 100), and blaZ (penicillin, 56%, 100%). Compared to penicillin, bla1 and blaZ had lower specificity for the prediction of ampicillin resistance. Overall, none of the ARGs had both high sensitivity and specificity, suggesting the need for further study of the mechanisms underlying phenotypic antimicrobial resistance in the B. cereus group. IMPORTANCE Bacillus cereus group includes human pathogens that can cause severe infections requiring antibiotic treatment. Screening of environmental and food isolates for antimicrobial resistance can provide insight into what antibiotics may be more effective therapeutic options based on the lower prevalence of resistance. Currently, the comparison of antimicrobial susceptibility testing results using the disk diffusion method is complicated by the fact that many previous studies have used Staphylococcus spp. breakpoints to interpret their results. In this study, we compared the results of disk diffusion interpreted using the Staphylococcus spp. breakpoints against the results of broth microdilution interpreted using Bacillus spp. breakpoints. We demonstrated that the disk diffusion method does not produce reliable results for B. cereus group isolates and should therefore be avoided. This study also provides new insight into poor associations between the presence of antimicrobial resistance genes and resistance phenotypes for the B. cereus group.

The pathogenic biomarker alcohol dehydrogenase protein is involved in Bacillus cereus virulence and survival against host innate defence

Bacillus cereus is a spore forming bacteria recognized among the leading agents responsible for foodborne outbreaks in Europe. B. cereus is also gaining notoriety as an opportunistic human pathogen inducing local and systemic infections. The real incidence of such infection is likely underestimated and information on genetic and phenotypic characteristics of the incriminated strains is generally scarce. We have recently analyzed a large strain collection of varying pathogenic potential. Screening for biomarkers to differentiate among clinical and non-clinical strains, a gene encoding an alcohol dehydrogenase-like protein was identified among the leading candidates. This family of proteins has been demonstrated to be involved in the virulence of several bacterial species. The relevant gene was knocked out to elucidate its function with regards to resistance to host innate immune response, both in vitro and in vivo. Our results demonstrate that the adhB gene plays a significant role in resistance to nitric oxide and oxidative stress in vitro, as well as its pathogenic ability with regards to in vivo toxicity. These properties may explain the pathogenic potential of strains carrying this newly identified virulence factor.

Biofertilizer microorganisms accompanying pathogenic attributes: a potential threat

Application of biofertilizers containing living or dormant plant growth promoting bacterial cells is considered to be an ecofriendly alternative of chemical fertilizers for improved crop production. Biofertilizers opened myriad doors towards sustainable agriculture as they effectively reduce heavy use of chemical fertilizers and pesticides by keeping soils profuse in micro and macronutrients, regulating plant hormones and restraining infections caused by the pests present in soil without inflicting environmental damage. Generally, pathogenicity and biosafety testing of potential plant growth promoting bacteria (PGPB) are not performed, and the bacteria are reported to be beneficial solely on testing plant growth promoting characteristics. Unfortunately, some rhizosphere and endophytic PGPB are reported to be involved in various diseases. Such PGPB can also spread virulence and multidrug resistance genes carried by them through horizontal gene transfer to other bacteria in the environment. Therefore, deployment of such microbial populations in open fields could lead to disastrous side effects on human health and environment. Careless declaration of bacteria as PGPB is more pronounced in research publications. Here, we present a comprehensive report of declared PGPB which are reported to be pathogenic in other studies. This review also suggests the employment of some additional safety assessment protocols before reporting a bacteria as beneficial and product development.

Implication of a Key Region of Six Bacillus cereus Genes Involved in Siroheme Synthesis, Nitrite Reductase Production and Iron Cluster Repair in the Bacterial Response to Nitric Oxide Stress

Bacterial response to nitric oxide (NO) is of major importance for bacterial survival. NO stress is a main actor of the eukaryotic immune response and several pathogenic bacteria have developed means for detoxification and repair of the damages caused by NO. However, bacterial mechanisms of NO resistance by Gram-positive bacteria are poorly described. In the opportunistic foodborne pathogen Bacillus cereus, genome sequence analyses did not identify homologs to known NO reductases and transcriptional regulators, such as NsrR, which orchestrate the response to NO of other pathogenic or non-pathogenic bacteria. Using a transcriptomic approach, we investigated the adaptation of B. cereus to NO stress. A cluster of 6 genes was identified to be strongly up-regulated in the early phase of the response. This cluster contains an iron-sulfur cluster repair enzyme, a nitrite reductase and three enzymes involved in siroheme biosynthesis. The expression pattern and close genetic localization suggest a functional link between these genes, which may play a pivotal role in the resistance of B. cereus to NO stress during infection.

The interaction between flagellin and the glycosphingolipid Gb3 on host cells contributes to Bacillus cereus acute infection

Bacillus cereus

is an opportunistic pathogen that can cause emetic or diarrheal foodborne illness. Previous studies have identified multiple pathogenic B. cereus strains and characterized a variety of virulence factors. Here, we demonstrate that the virulence and lethality of B. cereus for mammalian cells and host animals involve the interaction of B. cereus flagellin proteins and the host-cell-surface-localized glycosphingolipid Gb3 (CD77, Galα1-4Galβ1-4Glcβ1-Cer). We initially found that B. cereus infection was less lethal for Gb3-deficiencient A4galt^−/- mice than for wild-type mice. Subsequent experiments established that some factor other than secreted toxins must account of the observed differential lethality: Gb3-deficiencient A4galt^−/- mice were equally susceptible to secreted-virulence-factor-mediated death as WT mice, and we observed no differences in the bacterial loads of spleens or livers of mice treated with B. cereus strain vs. mice infected with a mutant variant of incapable of producing many secreted toxins. A screen for host-interacting B. cereus cell wall components identified the well-known flagellin protein, and both flagellin knockout strain assays and Gb3 inhibitor studies confirmed that flagellin does interact with Gb3 in a manner that affects B. cereus infection of host cells. Finally, we show that treatment with polyclonal antibody against flagellin can protect mice against B. cereus infection. Thus, beyond demonstrating a previously unappreciated interaction between a bacterial motor protein and a mammalian cell wall glycosphingolipid, our study will provide useful information for the development of therapies to treat infection of B. cereus.

The cytotoxic potential of Bacillus cereus strains of various origins

B. cereus is a human pathogen associated with food poisoning leading to gastrointestinal disorders, as well as local and severe systemic infections. The pathogenic spectrum of B. cereus ranges from strains used as probiotics in humans to lethal highly toxic strains. In this study, we gathered a collection of 100 strains representative of the pathological diversity of B. cereus in humans, and characterized these strains for their cytotoxic potential towards human cells. We analyzed the correlation between cytotoxicity to epithelial and macrophage cells and the combination of 10 genes suspected to play a role during B. cereus virulence. We highlight genetic differences among isolates and studied correlations between genetic signature, cytotoxicity and strain pathological status. We hope that our findings will improve our understanding of the pathogenicity of B. cereus, thereby making it possible to improve both clinical diagnosis and food safety.

The Food Poisoning Toxins of Bacillus cereus

Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.

Assessment and molecular characterization of Bacillus cereus isolated from edible fungi in China

Background

Bacillus cereus is a foodborne pathogen commonly found in nature and food and can cause food spoilage and health issues. Although the prevalence of B. cereus in foods has been reported worldwide, the extent of contamination in edible fungi, which has become increasingly popular as traditional or functional food, is largely unknown. Here we investigated the prevalence, toxin genes’ distribution, antibiotic resistance, and genetic diversity of B. cereus isolated from edible fungi in China.

Results

Six hundred and ninety-nine edible fungi samples were collected across China, with 198 (28.3%) samples found to be contaminated by B. cereus, with an average contamination level of 55.4 most probable number (MPN)/g. Two hundred and forty-seven B. cereus strains were isolated from the contaminated samples. Seven enterotoxin genes and one cereulide synthetase gene were detected. The detection frequencies of all enterotoxin genes were ≥ 80%, whereas the positive rate of the cesB gene in B. cereus was 3%. Most isolates were resistant to penicillins, β-lactam/β-lactamase inhibitor combinations, cephems, and ansamycins, but were susceptible to penems, aminoglycosides, macrolides, ketolide, glycopeptides, quinolones, phenylpropanol, tetracyclines, lincosamides, streptogramins, and nitrofurans. Meanwhile, 99.6% of all isolates displayed multiple antimicrobial resistance to three or more classes of antimicrobials. Using genetic diversity analysis, all isolates were defined in 171 sequence types (STs), of which 83 isolates were assigned to 78 new STs.

Conclusions

This study provides large-scale insight into the prevalence and potential risk of B. cereus in edible fungi in China. Approximately one-third of the samples were contaminated with B. cereus, and almost all isolates showed multiple antimicrobial resistance. Detection frequencies of all seven enterotoxin genes were equal to or more than 80%. These new findings may indicate a need for proper pre-/post-processing of edible fungi to eliminate B. cereus, thereby preventing the potential risk to public health.

Bacterial contamination of protective lead garments in an operating room setting

Background

Protective lead garments (PLG) worn in the operating room are a potential source for bacterial colonisation and thus may increase the risk of intraoperative infection. The clinical significance of such bacterial contamination has yet been established. Although disinfection protocols have been employed, their effectiveness is also unknown.

Objective

We sought to describe and compare the bacterial profile of PLGs with a focus on common pathogens involved in surgical site infections (SSI) and prosthetic joint infections (PJI).

Methods

We studied body aprons and neck-thyroid protective shields. We sampled 20 body aprons and 21 neck PLGs, swabbing the inside and outside of the PLGs. Swabs were cultured on different media and the results were assessed and compared.

Results

Of PLGs, 87.8% were contaminated. The neck-thyroid shield PLGs was generally more contaminated than body apron PLGs and exhibited significantly higher loads of Staphylococcus epidermidis (P = 0.048). Other pathogen cultured were Micrococcus spp., Acinetobacter lwoffii (A. lwoffii), Bacillus species (Bacillus spp.), Moraxella osloensis (M. osloensis) and Pseudomonas stutzeri (P. stutzeri). No other common pathogens associated with SSI or PJI were detected.

Conclusions

PLGs are heavily contaminated despite regular cleaning protocols. Neck PLGs are highly contaminated with potentially infectious agents. As neck PLGs are often directly exposed above the surgical sterile gown and the surgical field, measures should be undertaken to reduce their exposure and bacterial load, perhaps by suggesting users consider avoiding the use of intraoperative fluoroscopy when possible or alternatively supporting the use of body exhaust suits when PLGs are needed.

Prevalence, Virulence Feature, Antibiotic Resistance and MLST Typing of Bacillus cereus Isolated From Retail Aquatic Products in China

Bacillus cereus is one of the most important foodborne pathogenic microorganisms, which can lead to gastrointestinal and non-gastrointestinal diseases. However, the potential risk of B. cereus in aquatic products in China has not been comprehensively evaluated yet. In this study, a total of 860 aquatic samples from three types of retail aquatic products were collected from 39 major cities in China from 2011 to 2016. The contamination, distribution of virulence genes, antibiotic resistance and genetic diversity of B. cereus isolates were measured and analyzed. Of all the samples, 219 (25.47%) were positive for B. cereus and 1.83% (4/219) of the samples had contamination levels of more than 1,100 most probable number (MPN)/g. Different isolates had virulence potential, within which 59.6% (164/275) contained all three kinds of enterotoxin genes (nhe, hbl, and cytK-2) and 5.1% (14/275) possessed cereulide encoding gene cesB. The antimicrobial resistance profiles revealed the universal antibiotic resistance to rifampin and most β-lactams, suggesting the necessity to continuously monitor the antibiotic resistance of B. cereus in aquatic products and to control drug use in aquaculture. In sum, our study indicates the potential hazards of B. cereus isolated from aquatic products to customers and may provide a reference for clinical treatment caused by B. cereus.

Bacillus cereus bacteremia in a patient with an abdominal stab wound

Bacillus cereus is a gram positive microorganism commonly involved in gastrointestinal infection but capable of causing severe infections and bacteremia. We describe here a case of bacteremia caused by B. cereus in a previously healthy young woman admitted to the intensive care unit following emergency surgery due to a penetrating abdominal stab wound and subsequent hepatic lesion. She developed fever during admission and cultures were taken. B. cereus was isolated in blood and hepatic fluid collection cultures. Treatment was adjusted according to the isolate, with good clinical results. It is important to highlight the pathogenic potential of this microorganism and not underestimate it as a contaminant when it is isolated from blood samples.

Bacillus cereus isolated from a positive bone tissue culture in a patient with osteolysis and high-titer anti-interferon-γ autoantibodies: A case report

RATIONALE

Bacillus cereus (B cereus) is an aerobic or facultative anaerobic gram-positive, spore-forming bacterium. It can cause fatal disease and generally manifests as 3 distinct syndromes: food intoxication, localized infection, and systemic infection. It is a rare infection that can occur in immunocompetent persons with osteolytic and high-titer anti-IFN-γ autoantibodies.

PATIENT CONCERNS

We reported a case of an HIV-negative 24-year old man with an interrupted fever and a 20-day history of progressive ache in the right thigh and high-titer anti-IFN-γ autoantibodies. Magnetic resonance imaging, X-radiography, high-resolution computed tomography, and 3-dimensional reconstruction of the bone showed multiple lucent defects with moth-eaten destruction of the bone and cortical substance of bone in the right femur. Emission CT showed significantly increased uptake in the femur.

DIAGNOSIS AND INTERVENTIONS

The patient was originally misdiagnosed with osteosarcoma; acute osteomyelitis was also considered. He received intravenous piperacillin, sulbactam, and levofloxacin during hospitalization; however, he did not respond to the 3-week antibiotic course and his condition worsened. After cultures from incisional biopsy specimens were obtained from the femoral cavity, B cereus-induced osteomyelitis was diagnosed. He received intravenous injections of moxifloxacin 400 mg qd for 4 weeks and oral moxifloxacin 400 mg qd for 8 weeks.

OUTCOMES

The patient's symptoms and signs improved. His X-radiography, HRCT, MRI, and 3-dimensional reconstruction of the bone showed absolute absorption in the right femur. However, the anti-IFN-γ autoantibody titer was still high. No recurrence was observed after 24 months of follow-up. He is still undergoing follow-up at this time.

LESSONS

This is the first case involving a patient with B cereus infection showing a high titer of anti-IFN-γ autoantibodies. B cereus infection can involve the bone, leading to osteolysis in HIV-negative individuals. Although this patient was HIV-negative and had no other comorbidities, the presence of high titer anti-IFN-γ autoantibodies may be the primary reason for B cereus infection. Clinicians should pay more attention to the identification of osteolytic destruction caused by tumor and infection.

Mechanism of action of the moonlighting protein EfTu as a Substance P sensor in Bacillus cereus

The striking feature of the ubiquitous protein EfTu (Thermo unstable ribosomal Elongation factor) is its moonlighting (multifunctional) activity. Beyond its function at the ribosomal level it should be exported to the bacterial surface and act as an environmental sensor. In Bacillus cereus, and other cutaneous bacteria, it serves as a Substance P (SP) receptor and is essential for bacterial adaptation to the host. However, the modus operandi of EfTu as a bacterial sensor remains to be investigated. Studies realized by confocal and transmission electron microscopy revealed that, in the absence of an exogenous signal, EfTu is not exposed on the bacterial surface but is recruited under the effect of SP. In addition, SP acts as a transcriptional regulator of the tuf gene encoding for EfTu. As observed using gadolinium chloride, an inhibitor of membrane mechanosensitive channels (Msc), Msc control EfTu export and subsequently the bacterial response to SP both in terms of cytotoxicity and biofilm formation activity. Microscale thermophoresis revealed that in response to SP, EfTu can form homopolymers. This event should occur after EfTu export and, as shown by proteo-liposome reconstruction studies, SP appears to promote EfTu polymers association to the membrane, leading subsequently to the bacterial response. Molecular modeling suggests that this mechanism should involve EfTu unfolding and insertion into the bacterial cytoplasmic membrane, presumably through formation of homopolymers. This study is unraveling the original mechanism action of EfTu as a bacterial sensor but also reveals that this protein should have a broader role, including in eukaryotes.

Bacillus cereus, a serious cause of nosocomial infections: Epidemiologic and genetic survey

Bacillus cereus is the 2^nd most frequent bacterial agent responsible for food-borne outbreaks in France and the 3^rd in Europe. In addition, local and systemic infections have been reported, mainly describing individual cases or single hospital setting. The real incidence of such infection is unknown and information on genetic and phenotypic characteristics of the incriminated strains is generally scarce. We performed an extensive study of B. cereus strains isolated from patients and hospital environments from nine hospitals during a 5-year study, giving an overview of the consequences, sources and pathogenic patterns of B. cereus clinical infections. We demonstrated the occurrence of several hospital-cross-contaminations. Identical B. cereus strains were recovered from different patients and hospital environments for up to 2 years. We also clearly revealed the occurrence of inter hospital contaminations by the same strain. These cases represent the first documented events of nosocomial epidemy by B. cereus responsible for intra and inter hospitals contaminations. Indeed, contamination of different patients with the same strain of B. cereus was so far never shown. In addition, we propose a scheme for the characterization of B. cereus based on biochemical properties and genetic identification and highlight that main genetic signatures may carry a high pathogenic potential. Moreover, the characterization of antibiotic resistance shows an acquired resistance phenotype for rifampicin. This may provide indication to adjust the antibiotic treatment and care of patients.

The Bacterial Mfd Protein Prevents DNA Damage Induced by the Host Nitrogen Immune Response in a NER-Independent but RecBC-Dependent Pathway

Production of reactive nitrogen species is an important component of the host immune defence against bacteria. Here, we show that the bacterial protein Mfd (Mutation frequency decline), a highly conserved and ubiquitous bacterial protein involved in DNA repair, confers bacterial resistance to the eukaryotic nitrogen response produced by macrophage cells and during mice infection. In addition, we show that RecBC is also necessary to survive this stress. The inactivation of recBC and mfd genes is epistatic showing that Mfd follows the RecBC repair pathway to protect the bacteria against the genotoxic effect of nitrite. Surprisingly given the role of Mfd in transcription-coupled repair, UvrA is not necessary to survive the nitrite response. Taken together, our data reveal that during the eukaryotic nitrogen response, Mfd is required to maintain bacterial genome integrity in a NER-independent but RecBC-dependent pathway.

Central Venous Access Device-Related Bacillus Cereus Endocarditis: A Case Report and Review of the Literature

Bacillus cereus typically presents as a gastrointestinal infection, but rarely manifests as systemic disease. This report describes a case of B. cereus-related endocarditis that presented as a sickle cell crisis and bacteremia. Initial clinical suspicion was for laboratory contamination of blood cultures. The case herein described is intended to demonstrate an uncommon presentation of B. cereus infection and highlights the value of an aggressive need to further investigate and interpret unexpected blood culture findings in clinical practice, early adequate antimicrobial therapy, prompt diagnosis, and consideration to urgent surgical interventions in such cases.

The global regulator CodY is required for the fitness of Bacillus cereus in various laboratory media and certain beverages

The impact of gene mutations on the growth of the cells can be studied using pure cultures. However, the importance of certain proteins and pathways can be also examined via co-culturing wild type and its mutant derivative. Here, the relative fitness of a mutant strain that lacks the global nitrogen regulator, CodY, was examined in Bacillus cereus, a food poisoning Gram-positive bacterium. Fitness measurements revealed that the ΔcodY strain was outcompeted when cocultured with the wild-type ATCC 14579 under various rich laboratory medium, and also when inoculated in certain beverages. In nutrient-poor minimal medium, the ΔcodY mutant had comparable fitness to the wild-type strain. Interestingly, the relative fitness of the ΔcodY strain was antagonistic when it was cultivated in apple or orange juices due to unknown properties of these beverages, highlighting the importance of chemical composition of the test medium during the bacterial fitness measurements.