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

BACKGROUND: Bacillus cereus is a gram-positive rod bacterium that is responsible for food poisoning. It is naturally widely distributed, and thus often contaminates cultures. Although it is rarely considered responsible, it can cause serious infections under certain conditions. However, lethal infections, especially in immunocompetent patients, are rare. CASE PRESENTATION: A healthy 60-year-old man developed community-acquired B. cereus pneumonia and alveolar hemorrhage unveiled by abrupt chest pain and hemoptysis with no other advance symptoms. B. cereus induced silent alveolar destruction without any local or systemic inflammatory response. Although the lesion resembled lung anthrax, there was no evidence of Bacillus anthracis toxin. CONCLUSIONS: Some isolates of B. cereus can cause anthrax-like fulminant necrotizing pneumonia in immunocompetent patients. If this type of B. cereus were used as a means of bioterrorism, it may be quite difficult to recognize as bioterrorism. We should keep B. cereus in mind as a potential pathogen of fulminant human infectious disease.

[A sepsis case caused by a rare opportunistic pathogen: Bacillus pumilus]. / Nadir görülen firsatçi patojen Bacillus pumilus'un neden oldugu bir sepsis olgusu.

The high prevalence of Bacillus species in nature and the detection of these bacteria as contaminant in cultures may lead diagnostic dilemma, however they should still be considered as a pathogen particularly in case of repeated positive cultures from patients with risk factors. Bacillus pumilus is a bacteria, though rarely, been reported as the causative agent of various infections such as sepsis, endocarditis, skin infections and food poisoning in human. In this report, a sepsis case in an immunocompetent patient caused by B.pumilus was presented. A 38-year-old female patient was admitted to emergency service of our hospital with the complaints of headache, dizziness and diarrhea. She had not any risk factors except a history of heart valve replacement operation two years ago. In physical examination, she had abdominal retention, high fever and hypotension, together with the high levels of sedimentation rate (ESR) and C-reactive protein (CRP). The patient was hospitalized with the preliminary diagnosis of sepsis. Three sets of blood samples at two different periods were taken for the culture. All blood culture vials had a positive signal at the second day of incubation in BD BACTEC™ 9050 system, therefore subcultures were performed in sheep blood agar, chocolate agar and MacConkey agar, and incubated in aerobic and anaerobic conditions. Beta-haemolytic, gray-colored large colonies were isolated from anaerobic culture at the end of 18-24 hours incubation, and Gram staining from colonies showed gram-positive rods. The isolate was identified as B.pumilus with 99% accuracy rate by using BD Phoenix™ 100 identification system. This result was also confirmed by MALDI-TOF based VITEK® MS system and 16S rRNA sequencing by Illumina MiSeq® platform. Antibiotic susceptibility test performed by BD Phoenix™ 100 system and the isolate was found to be resistant against penicillin, while it was susceptible to vancomycin, erythromycin, clindamycin, levofloxacin, and trimethoprim-sulfamethoxazole. Initial treatment of patient was started with intravenous ceftriaxone and metronidazole empirically. Hypotension and fever returned to normal levels at the second and third days of the treatment, respectively. Metronidazole treatment was stopped at seventh day, and treatment was completed to 14 day with ceftriaxone alone. At the end of the treatment course, general condition of the patient was completely good, ESR and CRP were also decreased to normal levels. In conclusion, although most of the reported bloodstream infections that are caused by B.pumilus are intravascular catheter-related, artificial heart valves should also be considered as a risk factor even though vegetation was not detected in our patient.

Massive horizontal gene transfer, strictly vertical inheritance and ancient duplications differentially shape the evolution of Bacillus cereus enterotoxin operons hbl, cytK and nhe.

BACKGROUND: Bacillus cereus sensu lato comprises eight closely related species including the human pathogens Bacillus anthracis and Bacillus cereus. Within B. cereus sensu lato, chromosomally and plasmid-encoded toxins exist. While plasmid-mediated horizontal gene transfer of the emetic toxin, anthrax and insecticidal toxins is known, evolution of enterotoxin genes within the group has not been studied. RESULTS: We report draft genome assemblies of 25 strains, a phylogenetic network of 142 strains based on ANI derived from genome sequences and a phylogeny based on whole-genome SNP analysis. The data clearly support subdivision of B. cereus sensu lato into seven phylogenetic groups. While group I, V and VII represent B. pseudomycoides, B. toyonensis and B. cytotoxicus, which are distinguishable at species level (ANI border ≥ 96 %), strains ascribed to the other five species do not match phylogenic groups. The chromosomal enterotoxin operons nheABC and hblCDAB are abundant within B. cereus both isolated from infections and from the environment. While the duplicated hbl variant hbl a is present in 22 % of all strains investigated, duplication of nheABC is extremely rare (0.02 %) and appears to be phylogenetically unstable. Distribution of toxin genes was matched to a master tree based on seven concatenated housekeeping genes, which depicts species relationships in B. cereus sensu lato as accurately as whole-genome comparisons. Comparison to the phylogeny of enterotoxin genes uncovered ample evidence for horizontal transfer of hbl, cytK and plcR, as well as frequent deletion of both toxins and duplication of hbl. No evidence for nhe deletion was found and stable horizontal transfer of nhe is rare. Therefore, evolution of B. cereus enterotoxin operons is shaped unexpectedly different for yet unknown reasons. CONCLUSIONS: Frequent exchange of the pathogenicity factors hbl, cytK and plcR in B. cereus sensu lato appears to be an important mechanism of B. cereus virulence evolution, including so-called probiotic or non-pathogenic species, which might have consequences for risk assessment procedures. In contrast, exclusively vertical inheritance of nhe was observed, and since nhe-negative strains appear to be extremely rare, we suggest that fitness loss may be associated with deletion or horizontal transfer of the nhe operon.

[A Case of Delayed Vascular Injury as a Complication Related to Implanted Central Venous Port Catheter].

A 74-year-old woman with advanced gastric cancer was admitted to our hospital. A central venous (CV) port catheter was implanted into the right subclavian vein for preoperative chemotherapy and parenteral nutritional management. On the 35th day after implantation, she complained of diarrhea, fever and dyspnea. The chest radiograph showed a right-sided massive pleural effusion. As the patient progressively fell into severe respiratory distress, endotracheal intubation was performed for management of respiration by mechanical ventilation. Initially, given the patient's symptoms, she was diagnosed with septic shock. Therefore, after placement of a CV catheter through the right femoral vein, in consideration of the possibility of a port infection, she was treated with thoracentesis and infusion of antibiotics. The patient gradually recovered, and again received parenteral nutrition through the CV port catheter. After the infusion was administered, she complained of dyspnea. A CT scan of the chest revealed a right pleural effusion and displacement of the tip of the CV port catheter out of the wall of the superior vena cava. We diagnosed delayed vascular injury (DVI), and the CV port catheter was removed. She soon recovered with conservative treatment. We speculated that the initial respiratory symptoms such as the pleural effusion were caused by DVI. DVI should therefore be recognized as a complication related to implanted CV port catheters.

Seasonal trend and clinical presentation of Bacillus cereus bloodstream infection: association with summer and indwelling catheter.

Bacillus cereus, an opportunistic pathogen, can cause fatal infection. However, B. cereus bloodstream infections (BSIs) have not been well characterised. From 2008 to 2013, B. cereus isolates from all of the specimens and patients with B. cereus BSIs were identified. Environmental samples were collected to detect B. cereus contamination. We also characterised the clinical presentation of B. cereus BSI through analyses of risk factors for BSI and mortality. A total of 217 clinical B. cereus isolates was detected. Fifty-one patients with nosocomial infections were diagnosed as B. cereus BSI, and 37 had contaminated blood cultures. The number of B. cereus isolates and BSI patients was significantly greater from June to September than from January to April (4.9 vs. 1.5 per month and 1.2 vs. 0.2, respectively). All BSIs were nosocomial and related to central or peripheral vascular catheter. Urinary catheter [odds ratio (OR) 6.93, 95% confidence interval (CI) 2.40-20.0] was the independent risk factor associated with BSI patients when compared to patients regarded as contaminated. In-hospital mortality among BSI patients was 20% and was associated with urinary catheter (OR 34.7, 95 % CI 1.89-63.6) and higher Charlson index (OR 1.99, 95 % CI 1.26-3.12). The number of B. cereus isolates and BSI increased during summer. Inpatients with indwelling vascular or urinary catheters should be carefully monitored for potential B. cereus BSIs.

Bacillus cereus G9241 S-layer assembly contributes to the pathogenesis of anthrax-like disease in mice.

Bacillus cereus G9241, the causative agent of anthrax-like disease, harbors virulence plasmids encoding anthrax toxins as well as hyaluronic acid (HA) and B. cereus exopolysaccharide (BPS) capsules. B. cereus G9241 also harbors S-layer genes, including homologs of Bacillus anthracis surface array protein (Sap), extractable antigen 1 (EA1), and the S-layer-associated proteins (BSLs). In B. anthracis, S-layer proteins and BSLs attach via their S-layer homology domains (SLH) to the secondary cell wall polysaccharide (SCWP) in a manner requiring csaB, a predicted ketalpyruvate transferase. Here we used a genetic approach to analyze B. cereus G9241 S-layer assembly and function. Variants lacking the csaB gene synthesized SCWP but failed to retain Sap, EA1, and BSLs in the bacterial envelope. The B. cereus G9241 csaB mutant assembled capsular polysaccharides but displayed an increase in chain length relative to the wild-type strain. This phenotype is likely due to its inability to deposit BslO murein hydrolase at divisional septa. During growth under capsule-inducing conditions, B. cereus G9241 assembled BSLs (BslA and BslO) and the Sap S-layer protein, but not EA1, in the envelope. Finally, csaB-mediated assembly of S-layer proteins and BSLs in B. cereus G9241 contributes to the pathogenesis of anthrax-like disease in mice.

Possible contamination of organ preservation fluid with Bacillus cereus: the United Kingdom response.

We describe here the United Kingdom (UK) response following the recent international recall of an organ preservation fluid owing to potential Bacillus cereus contamination. This fluid is used for the transport of solid organs and pancreatic islet cells for transplant. We detail the response mechanisms, including the initial risk stratification, investigatory approaches, isolate analysis and communications to professional bodies. This report further lays out the potential need for enhanced surveillance in UK transplant patients.

A deep-sea pathogenic Bacillus subtilis isolate employs different strategies to escape the killing of teleost and murine complements.

Bacillus subtilis subsp. subtilis G7 was isolated from a deep-sea hydrothermal vent and is pathogenic to pathogenic to fish (Japanese flounder) and mice. G7 is able to survive in host sera and phagocytes. In this study, we investigated the underlying mechanism of G7 serum resistance. We found that (i) the remaining complement activity was very low in G7-incubated flounder serum but high in G7-incubated mouse serum; (ii) cleaved C3 and C5 components were detected on flounder serum-incubated G7 but not on mouse serum-incubated G7; (iii) abundant uncleaved C5 was localized in G7-incubated mouse, but not flounder, serum; (iv) G7-incubated flounder, but not mouse, serum exhibited strong chemotactic activity; (v) pre-treatment with low-dose lysozyme abolished the serum resistance of G7. Hence, G7 activates flounder complement but is protected from complement-mediated destruction by its cell wall structure, while G7 prevents the activation of mouse complement. These results indicate that G7 employs different mechanisms to avoid the complement killing of different hosts.

Periorbital cellulitis caused by Bacillus thuringiensis.

PURPOSE: Periorbital cellulitis is an inflammation of the lids and periorbital tissues without signs of true involvement such as proptosis or limitation of eye movement. METHODS: Bacillus thuringiensis is a Gram-positive, spore-forming soil bacterium with the ability to produce insecticidal crystal proteins. B thuringiensis is an extremely rare causative organism of orbital and periorbital infections. However, it was rarely seen isolated in pediatric cases with preseptal cellulites. Ocular infections of this bacteria quickly progress, within 12-48 hours from inoculation, leading to endophthalmitis or panophthalmitis and irreversible vision loss. RESULTS: Periorbital cellulitis should be recognized promptly and treated carefully. Hospitalization, prompt systemic antibiotic therapy, and careful monitoring for signs of sepsis and local invasion are critical. CONCLUSIONS: We report a rare presentation of periorbital cellulitis caused by B thuringiensis.

Food poisoning associated with emetic-type of Bacillus cereus in Korea.

Bacillus cereus can cause diarrheal and emetic types of food poisoning but little study has been done on emetic type of food poisoning in Korea. The objective of this study was to report on the emetic type of food poisoning associated with B. cereus in Korea. The toxin gene profile, toxin production, and antibiotic resistance of B. cereus isolates were investigated in this study. B. cereus was detected in three out of four samples, while the other food poisoning bacteria were not detected. All isolates (KUGH 10, 11, and 12) presented nhe A, B, and C diarrheal toxin genes (755, 743, and 683 bp), detected using NHA, NHB, and NHC primers, and ces emetic toxin gene (1271 bp), detected using CES primer, and produced nonhemolytic enterotoxin and emetic toxin (cereulide), detected using immunochemical assay and high performance liquid chromotography/mass spectrometry (HPLC/MS) analysis. All emetic-associated isolates were resistant to beta-lactam antibiotics. Most important finding in this study was that the risk of emetic-type B. cereus food poisoning has existed in Korea. This suggested that the food poisoning caused by B. cereus producing emetic and diarrheal toxins should be constantly evaluated to prevent misdiagnosis between emetic and diarrheal types of food poisoning.

Ba813 harboring Bacillus cereus, genetically closely related to Bacillus anthracis, causing nosocomial bloodstream infection: Bacterial virulence factors and clinical outcome.

Bacillus cereus commonly causes catheter-related bloodstream infections (BSIs) in hospital settings, and occasionally occurs fatal central nervous system (CNS) complications. B. cereus harboring Ba813, a specific chromosomal marker of Bacillus anthracis, has been found in patients with severe infection and nosocomial BSI. However, the bacteriological profile and clinical feature of Ba813 (+) B. cereus are unclear. Fifty-three patients with B. cereus BSI were examined. Isolates were evaluated for Ba813, B. anthracis-related and food poisoning-related virulence, multilocus sequencing typing, and biofilm formation. Patients' clinical records were reviewed retrospectively. The 53 isolates were comprised of 29 different sequence types in two distinct clades. Seventeen of the 53 (32%) B. cereus isolates including five sequence types possessed Ba813 and were classified into Clade-1/Cereus-III lineage which is most closely related to Anthracis lineage. No B. cereus possessed B. anthracis-related virulence genes. Ba813 (+) strains showed a lower prevalence of enterotoxin genes than Clade-2 strains (n = 4), but no difference from Clade-1. Ba813 (+) strains showed significantly lower biofilm formation than Clade-1/non-Cereus-III (n = 22) and Clade-2 strains, respectively. Compared to Clade-1/non-Cereus-III and Clade-2 B. cereus, Ba813 (+) strains were isolated more frequently from elderly patients, patients with indwelling central venous catheter rather than peripheral venous catheter, and patients who remained in the hospital for longer before BSI onset. No significant differences in disease severity or mortality were observed. Though two of the ten Ba813 (-) strains in Clade-1/Cereus III were isolated from the patients with CNS complication, no significant difference was observed in the bacterial profile and clinical characteristics among Clade-1/Cereus III strains. In conclusion, our report suggested that Ba813-harboring B. cereus strains, genetically closely related to B. anthracis, were abundant among B. cereus strains in the hospital setting, and might cause catheter-related nosocomial BSI. However, it did not affect the clinical outcomes.

Bacillus Calmette-Guerin infection following intravesical instillation: Does the strain matter?

PURPOSE: Intravesical BCG is the standard treatment of non-muscle invasive bladder cancer. No difference has yet been reported in the safety profiles of the various BCG strains. METHODS: A nationwide multidisciplinary retrospective survey was conducted between January 2013 and December 2016 to identify cases of BCG infection and differentiate them based on the type of BCG strain used. RESULTS: Forty patients were identified (BCG RIVM 28; other strains 8; unknown 4). Patients treated with BCG RIVM were less severely ill, with fewer occurrences of septic shock (3.6% vs. 50%, P=0.003) and ICU admission (7.1% vs. 62.5%, P=0.003). A higher frequency of pulmonary miliaries (71.4% vs. 12.5%, P=0.005) but lower transaminase levels (mean AST 65 vs. 264 U/L, P=0.001) were observed in these patients. No difference in terms of recovery was reported. CONCLUSION: The type of BCG strain could correlate with the frequency and severity of subsequent BCG infections.

The YvfTU two-component system is involved in plcR expression in Bacillus cereus.

BACKGROUND: Most extracellular virulence factors produced by Bacillus cereus are regulated by the pleiotropic transcriptional activator PlcR. Among strains belonging to the B. cereus group, the plcR gene is always located in the vicinity of genes encoding the YvfTU two-component system. The putative role of YvfTU in the expression of the PlcR regulon was therefore investigated. RESULTS: Expression of the plcR gene was monitored using a transcriptional fusion with a lacZ reporter gene in a yvfTU mutant and in its B. cereus ATCC 14579 parental strain. Two hours after the onset of the stationary phase, a stage at which the PlcR regulon is highly expressed, the plcR expression in the yvfTU mutant was only 50% of that of its parental strain. In addition to the reduced plcR expression in the yvfTU mutant, a few members of the PlcR regulon showed a differential expression, as revealed by transcriptomic and proteomic analyses. The virulence of the yvfTU mutant in a Galleria mellonella insect model was slightly lower than that of the parental strain. CONCLUSION: The YvfTU two-component system is not required for the expression of most of the virulence factors belonging to the PlcR regulon. However, YvfTU is involved in expression of plcR, a major regulator of virulence in B. cereus.

Molecular identification of Exiguobacterium acetylicum as the aetiological agent of bacteraemia.

A case of catheter-related bacteraemia caused by Exiguobacterium acetylicum is reported in an elderly patient. The availability of sequence-based methods facilitated rapid identification and expanded the spectrum of diseases attributed to coryneform bacteria and specifically to the genus Exiguobacterium.

Toxinogenic Bacillus pumilus and Bacillus licheniformis from mastitic milk.

To elucidate the occurrence of heat-stable toxin-producing strains among mastitic Bacillus isolates, 100 milk samples of mastitic cows from different parts of Finland were screened. Bacillus was identified as the major organism in 23 samples. Toxinogenic Bacillus isolates identified by sperm cell motility inhibition assay were isolated from six samples. Four isolates belonged to the species Bacillus pumilus and two to Bacillus licheniformis. The toxic substances were heat-stable and soluble to methanol thus being of non-protein nature. The methanol extracted substances disrupted the sperm cell plasma membrane permeability barrier at exposure concentrations of 1-15 microg ml(-1) (B. pumilus) or 20-30 microg ml(-1) (B. licheniformis). The toxic properties of the two mastitic B. licheniformis strains were similar to those of B. licheniformis strains known to produce the lipopeptide lichenysin A and the synthetase genes lchAA, lchAB and lchAC for lichenysin were found in the mastitic strains by PCR. Toxin synthetase genes for the syntheses of lichenysin or surfactin were searched but not found in the toxic B. pumilus strains. The ribopatterns of the mastitic B. pumilus and B. licheniformis isolates were similar to those of the toxinogenic strains described earlier from food poisoning incidents and contaminated indoor air. B. licheniformis and B. pumilus survive pasteurization and other heat treatments as spores. Toxin-producing strains of these species in the dairy production chain may thus be of food safety concern.

Social and sexual behaviours aid transmission of bacteria in birds.

Understanding the behavioural mechanisms that mediate pathogen transmission in social hosts like birds could provide the empirical bases for explaining the epidemiological dynamics of zoonotic infections in vertebrates. By experimentally infecting the feathers and cloaca of captive zebra finches (Taeniopygia guttata), with the bacterium Bacillus licheniformis PWD1 (BL), we examined the self-contamination and horizontal transmission of birds sharing the same environment. We also examined whether sexual transmission of bacteria is gender biased. Our results show that bacteria placed on the plumage of the birds lead to self and allo-infections of the bird guts, possibly through preening behaviours and bacterial ingestion. Furthermore, we found that sexual transmission of the bacteria was asymmetrical, being higher when males are the transmitting sex. Our results suggest the existence of an oral-faecal-genital route of bacterial transmission for avian hosts, wherein bacteria present on feathers infect their host guts through self and allo-preening and bacterial ingestion. Gut bacteria can then be transmitted sexually with transmission rate being higher when males are the infected sex.

Acute inflammation and loss of retinal architecture and function during experimental Bacillus endophthalmitis.

Rapid vision loss and explosive inflammation are devastating consequences of Bacillus endophthalmitis that have not been well defined. We therefore analyzed the evolution of intraocular inflammation and loss of retinal architecture and function during experimental Bacillus endophthalmitis. Mice were intravitreally injected with 100 CFU of B. cereus, and eyes were analyzed for bacterial growth, retinal function, architectural changes and retinal cellular stress, inflammatory cytokines, and infiltrating cells. Retinal electrophysiologic and structural changes began as early as 4 to 6 hr postinfection. Significant declines in retinal function paralleled the loss of retinal architecture. Glial fibrillary acidic protein (GFAP) was detected in retina, indicating potential stress. Polymorphonuclear leukocyte (PMN) infiltration into the vitreous began as early as 4 hr postinfection, coinciding with a significant increase in TNF-alpha in the eye. These results indicated that acute inflammation and detrimental architectural and electrophysiologic changes in the retina began earlier than once thought, suggesting that therapeutic intervention should be given at the earliest possible time to avoid vision loss during Bacillus endophthalmitis.

Bacillus endophthalmitis: roles of bacterial toxins and motility during infection.

PURPOSE: Bacillus endophthalmitis is a highly explosive infection of the eye that commonly results in rapid inflammation and vision loss, if not loss of the eye itself, within a few days. Quorum-sensing-controlled toxins are essential to virulence during infection. Another unique characteristic of this disease is the ability of Bacillus to replicate rapidly and migrate to all parts of the eye. This study was conducted to determine the combined roles of toxins and motility during Bacillus endophthalmitis. METHODS: Rabbit eyes were injected intravitreally with approximately 100 cfu of wild type, nonmotile, or nonmotile/quorum-sensing-deficient Bacillus thuringiensis. Infection courses were analyzed by biomicroscopy, histology, electroretinography, and quantitation of bacteria and inflammatory cells. RESULTS: Infection with wild type B. thuringiensis resulted in complete retinal function loss by 18 hours after infection, whereas nonmotile B. thuringiensis infections required 30 hours to achieve a reduction of >90% in retinal function. Further attenuation of infection resulted from infection with the nonmotile/quorum-sensing-deficient B. thuringiensis strain, with approximately 90% retinal function loss occurring at 36 hours. Overall, the nonmotile and nonmotile/quorum-sensing-deficient mutants were significantly less virulent than wild-type B. thuringiensis. CONCLUSIONS: The results demonstrate that, in addition to quorum-sensing-controlled toxin production, bacterial migration within the eye contributed to the rapidly fulminant and destructive course of Bacillus endophthalmitis. Motility and quorum-sensing may therefore represent possible targets for the development of therapies designed to attenuate the devastating effects of Bacillus in the eye during endophthalmitis.

Multilocus sequence typing reveals that Bacillus cereus strains isolated from clinical infections have distinct phylogenetic origins.

Eight strains of Bacillus cereus isolated from bacteremia and soft tissue infections were assigned to seven sequence types (STs) by multilocus sequence typing (MLST). Two strains from different locations had identical STs. The concatenated sequences of the seven STs were aligned with 65 concatenated sequences from reference STs and a neighbor-joining tree was constructed. Two strains were distantly related to all reference STs. Three strains were recovered in a clade that included Bacillus anthracis, B. cereus and rare Bacillus thuringiensis strains while the other three strains were assigned to two STs that were more closely affiliated to most of the B. thuringiensis STs. We conclude that invasive B. cereus strains do not form a single clone or clonal complex of highly virulent strains.