Fatal community-acquired Bacillus cereus pneumonia in an immunocompetent adult man: a case report

Survival of community-acquired Bacillus cereus sepsis with venous sinus thrombosis in an immunocompetent adult man - a case report and literature review

BACKGROUND

Bacillus cereus infections in immunocompetent patients are uncommon and mainly observed in fragile patients. It can cause lethal infections with multiple organ dysfunction syndrome (MODS). However, a patient presenting as venous sinus thrombosis and survival without sequela has not been reported.

CASE PRESENTATION

A 20-year-old previously healthy male developed gastroenteritis after a meal, followed by fever, convulsions, and severe disturbance of consciousness. The patient had significant leukocytosis with a mildly elevated D-dimer, creatinine level, and respiratory failure. The CT(computed tomography) revealed fatal brain edema and subarachnoid hemorrhage. Previous blood culture in a local hospital revealed B. cereus, which was confirmed by mNGS(metagenomic next-generation sequencing) using blood and urine in our hospital. Accordingly, B. cereus sepsis with MODS were considered. Later, cerebral venous sinus thrombosis was proved. After anti-infection (linezolid 0.6 g, Q12h; and meropenem 1.0 g, Q8h), anti-coagulant (enoxaparin 6000U, Q12h), and other symptomatic treatments, the patient recovered completely without sequela at the 6-month follow-up.

CONCLUSIONS

This case suggests that in immunocompetent adults, there is still a risk of infection with B. cereus, causing severe MODS. Special attention should be paid to venous sinus thrombosis and subarachnoid hemorrhage in such cases, while, anti-coagulant is essential therapy.

Investigation of microorganisms in cannabis after heating in a commercial vaporizer

Introduction

There are concerns about microorganisms present on cannabis materials used in clinical settings by individuals whose health status is already compromised and are likely more susceptible to opportunistic infections from microbial populations present on the materials. Most concerning is administration by inhalation where cannabis plant material is heated in a vaporizer, aerosolized, and inhaled to receive the bioactive ingredients. Heating to high temperatures is known to kill microorganisms including bacteria and fungi; however, microbial death is dependent upon exposure time and temperature. It is unknown whether the heating of cannabis at temperatures and times designated by a commercial vaporizer utilized in clinical settings will significantly decrease the microbial loads in cannabis plant material.

Methods

To assess this question, bulk cannabis plant material supplied by National Institute on Drug Abuse (NIDA) was used to assess the impact of heating by a commercial vaporizer. Initial method development studies using a cannabis placebo spiked with Escherichia coli were performed to optimize culture and recovery parameters. Subsequent studies were carried out using the cannabis placebo, low delta-9 tetrahydrocannabinol (THC) potency and high THC potency cannabis materials exposed to either no heat or heating for 30 or 70 seconds at 190°C. Phosphate-buffered saline was added to the samples and the samples agitated to suspend the microorganism. Microbial growth after no heat or heating was evaluated by plating on growth media and determining the total aerobic microbial counts and total yeast and mold counts.

Results and discussion

Overall, while there were trends of reductions in microbial counts with heating, these reductions were not statistically significant, indicating that heating using standard vaporization parameters of 70 seconds at 190°C may not eliminate the existing microbial bioburden, including any opportunistic pathogens. When cultured organisms were identified by DNA sequence analyses, several fungal and bacterial taxa were detected in the different products that have been associated with opportunistic infections or allergic reactions including Enterobacteriaceae, Staphylococcus, Pseudomonas, and Aspergillus.

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.

Characterization of Bacillus cereus in Dairy Products in China

Bacillus cereus is a common and ubiquitous foodborne pathogen with an increasing prevalence rate in dairy products in China. High and unmet demands for such products, particularly milk, raise the risk of B. cereus associated contamination. The presence of B. cereus and its virulence factors in dairy products may cause food poisoning and other illnesses. Thus, this review first summarizes the epidemiological characteristics and analytical assays of B. cereus from dairy products in China, providing insights into the implementation of intervention strategies. In addition, the recent achievements on the cytotoxicity and mechanisms of B. cereus are also presented to shed light on the therapeutic options for B. cereus associated infections.

Sequential CRISPR-Based Screens Identify LITAF and CDIP1 as the Bacillus cereus Hemolysin BL Toxin Host Receptors

Bacteria and their toxins are associated with significant human morbidity and mortality. While a few bacterial toxins are well characterized, the mechanism of action for most toxins has not been elucidated, thereby limiting therapeutic advances. One such example is the highly potent pore-forming toxin, hemolysin BL (HBL), produced by the gram-positive pathogen Bacillus cereus. However, how HBL exerts its effects and whether it requires any host factors is unknown. Here, we describe an unbiased genome-wide CRISPR-Cas9 knockout screen that identified LPS-induced TNF-α factor (LITAF) as the HBL receptor. Using LITAF-deficient cells, a second, subsequent whole-genome CRISPR-Cas9 screen identified the LITAF-like protein CDIP1 as a second, alternative receptor. We generated LITAF-deficient mice, which exhibit marked resistance to lethal HBL challenges. This work outlines and validates an approach to use iterative genome-wide CRISPR-Cas9 screens to identify the complement of host factors exploited by bacterial toxins to exert their myriad biological effects.

An unusual case of massive hemoptysis due to Bacillus cereus necrotizing pneumonia

Bacillus cereus is a gram-positive bacillus that is ubiquitously present in the environment, often regarded as a contaminant when isolated in clinical testing. Cases of B. cereus causing lower respiratory tract infections are sparse, with less than 20 reported in the literature, and even fewer as a cause of massive hemoptysis. The majority of cases occur in the setting of an immunosuppressed patient. We describe a case of a 59-year-old male with esophageal adenocarcinoma undergoing chemotherapy presenting with a right upper lobe necrotizing pneumonia secondary to B. cereus with consequent massive hemoptysis.

Rapid Detection of Bacillus cereus Using Cross-Priming Amplification

Bacillus cereus is a spore-forming gastrointestinal pathogen that can cause life-threatening diseases. Here, a simple and effective assay to detect B. cereus was developed, using cross-priming amplification (CPA). Amplicons were detected using disposable cartridges that contained nucleic acid detection strips. The sensitivity of CPA assay for B. cereus was assessed using serial dilutions of genomic DNA, which indicated a detection limit of 3.6 × 10¹ CFU/mL. No cross-reactions were detected when genomic DNA extracted from 12 different B. cereus strains and 20 other bacterial foodborne strains were tested, suggesting that the assay is highly specific. Finally, we evaluated the practical applications of the CPA assay for the detection of B. cereus in 150 food samples and found that its sensitivity and specificity, compared with real-time PCR, were approximately 98.18 and 100%, respectively. In conclusion, CPA combined with nucleic acid detection strips is easy to perform, requires simple equipment, and offers highly specific and sensitive B. cereus detection.