Fulminant septicemic syndrome of Bacillus cereus in a leukemic patient

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.

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.

Successful treatment of postsurgical meningitis caused by Bacillus cereus: a case report and literature review

Bacillus cereus is a spore-forming, gram-positive bacterium that is ubiquitous in the environment. Central nervous system involvement with B. cereus is rare. Despite aggressive treatment with broad-spectrum antibiotics and using them appropriately, the mortality is high. A 72-year-old patient suffered a central nervous system infection associated with postsurgical meningitis and was successfully treated with a novel antibiotic therapy. This study includes the first case report of postsurgical B. cereus meningitis in the last ten years. It provides a different line of treatment to the previous ones.

Bacillus cereus meningoencephalitis in an immunocompetent patient

Central nervous system (CNS) infection from Bacillus cereus (B. cereus) is rare and usually occurs in immunosuppressed patients or in a presence of invasive CNS devices. Our case reported here is a very rare case of an immunocompetent elderly patient without any CNS devices who was diagnosed with B. cereus meningoencephalitis and bacteremia. According to our patient, preceding gastrointestinal (GI) symptoms and trans-sphenoidal hypophysectomy could be the precipitating factors. A positive blood culture should not be concluded as a contamination but prompt repeating another set of blood culture for a better clinical judgment. Given its abrupt clinical course and high mortality rate, high index of suspicion for rapid detection and management is needed for a preferable clinical outcome. Empiric treatment with intravenous vancomycin is reasonable before a susceptibility result becomes available.

•

CNS infection from B. cereus is rare and usually associated with CNS devices or immunosuppression.

•

B. cereus can cause meningoencephalitis in immunocompetent elderly patients without CNS device.

•

B. cereus in blood culture is not always a contaminant. Repeating blood culture is recommended.

•

Empiric treatment with vancomycin should be started before a susceptibility result is available.

Rapidly fatal infection with Bacillus cereus/thuringiensis: genome assembly of the responsible pathogen and consideration of possibly contributing toxins

Bloodstream infection with Bacillus cereus/thuringiensis can be life threatening, particularly in patients who are severely immunocompromised. In this report we describe a case that progressed from asymptomatic to fatal over approximately 5 hours despite extensive resuscitation efforts. We identify the pathogen and assemble its genome, in which we find genes for toxins that may have contributed to the precipitous demise. In the context of this and other cases we discuss the possible indication for rapid appropriate antibiotic administration and potentially antitoxin treatment or toxin removal in fulminant illness in immunocompromised patients.

Acute necrotising gastritis in a 14-year-old girl

A 14-year-old female patient presented with acute generalised abdominal pain and two attacks of non-bilious vomiting for 2 days. She visited the emergency department and at presentation she was pale, dyspnaeic and there was no jaundice. Abdominal examination showed moderate abdominal distension with generalised abdominal tenderness. The bowel sounds were negative on auscultation. Plain abdominal X-ray showed hugely distended stomach with no free air detected in the peritoneal cavity. During laparotomy there was huge distension and gangrene of the stomach involving the whole stomach up to the fundus. Total gastrectomy done with roux-en-y reconstruction of the gastrointestinal continuity. The histopathological study of the sample showed gastric necrosis.

Bacillus cereus Typhlitis in a Patient with Acute Myelogenous Leukemia: A Case Report and Review of the Literature

Bacillus cereus is a Gram-positive rod that is now recognized as a rare cause of frank disease in the neutropenic hematologic malignancy patient. Because this pathogen is rarely isolated in clinical specimens, no large studies exist to guide the management of these acutely ill patients. Individual case reports and case series exist in the literature describing various clinical manifestations of B. cereus in the neutropenic patient including bacteremia/septicemia, pneumonia, meningitis/encephalitis, hepatic abscesses, and gastritis. In this report, we describe a case of typhlitis caused by B. cereus in a 74-year-old female with recently diagnosed acute myelogenous leukemia (AML), and we summarize the available English language literature to draw tentative conclusions regarding the clinical manifestations of this organism.

Fulminant Bacillus cereus septicaemia with multiple organ ischaemic/haemorrhagic complications in a patient undergoing chemotherapy for acute myelogenous leukaemia

Bacillus cereus is a Gram-positive spore-forming rod widely found in the environment and is thought to be a frequent source of contamination. This micro-organism is reportedly a significant pathogenic agent among immunocompromised individuals. Furthermore, multiple cases of fulminant septicaemia have been reported among individuals receiving chemotherapy for acute myelogenous leukaemia. In some cases, B. cereus septicaemia was associated with multiple haemorrhages. We, herein, describe a patient with an extremely acute course of B. cereus septicaemia characterised by haemorrhage and infarction of multiple organs, which led to his death. Our findings suggest that delayed treatment of B. cereus in patients with haematologic malignancies undergoing chemotherapy may result in extremely poor outcomes; thus, immediate empirical treatment with vancomycin should be considered.

Molecular Characterization and Risk Assessment of Bacillus cereus Sensu Lato Isolated from Ultrahigh-Temperature and Pasteurized Milk Marketed in Rio de Janeiro, Brazil

The presence of Bacillus cereus in milk is a major concern in the dairy industry. In this study 27 Bacillus cereus sensu lato isolates from pasteurized and ultrahigh-temperature (UHT) milk (24 whole UHT and 4 pasteurized samples) collected at supermarket chains in Rio de Janeiro, Brazil, were evaluated to assess the potential risk for food poisoning. Toxigenic and virulence profiles were defined by gene-specific PCR. Affiliation to phylogenetic groups was assigned by panC sequencing. Microbiological analysis revealed the presence of B. cereus s.l. in eight (33.3%) brands (six brands of UHT and two brands of pasteurized milk). Twenty-seven isolates were recovered (13 B. cereus and 14 Bacillus thuringiensis ). Predominant toxigenic patterns were type I (contains all toxin genes except ces) and type II (does not contain cytK and ces), with seven (25.9%) isolates each. Predominant virulence patterns were type 2 (does not contain hlyII or shp) and type 3 (contains all virulence genes), with five (18.5%) isolates each. All isolates belonged to phylogenetic groups III and IV. Presence of hbl, piplc, and sph was associated with group IV isolates. Our results suggest that B. thuringiensis and B. cereus sensu stricto should be considered potential foodborne pathogens. Because the majority of the milk isolates studied have the potential to cause food poisoning because of the high prevalence of toxin and virulence genes and the specific phylogenetic group affiliations, these milk products can be potentially hazardous for human consumption.

Bacillus cereus bacteraemia: comparison between haematologic and nonhaematologic patients

Bacillus cereus bacteraemia can be severe, especially among patients with haematologic malignancy. We retrospectively reviewed first episodes of true B. cereus bacteraemia (more than one positive bottle plus signs of infection) at our institution between 1997 and 2013 with the aim to compare haematologic versus nonhaematologic patients and analyse episodes with complicated outcome. Among 56 episodes of positive-blood cultures for B. cereus, 21 were considered significant. Median age was 54 years (range 23-82 years). Ten patients (48%) had a haematologic malignancy; all were neutropenic at the time of B. cereus bacteraemia. Nonhaematologic patients were either intravenous drug users (n = 3, 14%), polytraumatized (n = 3, 14%) or had multiple chronic comorbidities (n = 5, 24%). Most episodes were hospital acquired (15, 71%). Sources of bacteraemia were intravascular catheter (n = 11, 52%), digestive tract (n = 6, 29%), drug injection (n = 3, 14%) and wound (n = 1, 5%). Adequate antibiotic therapy was provided to 18 patients (86%) during a median of 17 days (range 2-253 days). The intravascular catheter was removed in eight cases (42%). Three haematologic patients had a complicated course with neurologic complications (meningoencephalitis and cerebral abscesses). Complications appeared to be associated with catheter infection (100% of complicated cases vs. 29% of noncomplicated cases). In conclusion, B. cereus bacteraemia can have a complicated course in a subset of patients, mainly those with haematologic malignancy. Catheter infection may be associated with a worse outcome with frequent neurologic complications.

Murine model of Bacillus cereus gastrointestinal infection

Bacillus cereus is a spore-forming micro-organism responsible for foodborne illness. In this study, we focus on the host response following intragastric challenge with a pathogenic B. cereus strain (B10502) isolated from a foodborne outbreak. C57BL/6J female mice were infected by gavage with strain B10502. Controls were administered with PBS. Infection leads to significant modification in relevant immune cells in the spleen, Peyer's patches (PP) and mesenteric lymph nodes (MLN). These findings correlated with an increase in the size of PP as compared with uninfected controls. Histological studies showed that B. cereus infection increased the ratio of intestinal goblet cells and induces mononuclear cell infiltrates in spleen at 5 days post-infection. Evaluation of cytokine mRNA expression demonstrated a significant increase in IFN-γ in MLN after 2 days of infection. The present work demonstrates that infection of mice with vegetative B. cereus is self-limited. Our findings determined relevant cell populations that were involved in the control of the pathogen through modification of the ratio and/or activation.

Clinical features and risk factors for development of Bacillus bacteremia among adult patients with cancer: a case-control study

PURPOSE

Bacillus species have been frequently reported in recent decades as true pathogens among cancer patients. The purpose of this study was to evaluate the clinical features and risk factors of Bacillus bacteremia among adult patients with cancer.

METHODS

A case-control study was performed to identify the risk factors of Bacillus bacteremia among adult patients with cancer at a 1,950-bed tertiary care university hospital. Electronic medical records were reviewed for individuals who were diagnosed with Bacillus bacteremia during the period of January 1995 through December 2012. Each case was matched to two controls with cancer and non-Bacillus bacteremia. Logistic regression model was used to identify independent risk factors for Bacillus bacteremia development.

RESULTS

A total of 86 patients with Bacillus bacteremia were included and compared with 172 control patients. The presence of a central venous catheter and use of extended-spectrum cephalosporin within 1 month were identified to be independent risk factors for the development of Bacillus bacteremia. Hospital stays longer than 14 days, a history of hematopoietic stem cell transplantation, and prior use of glycopeptides had a negative association.

CONCLUSIONS

The presence of a central venous catheter and prior use of extended-spectrum cephalosporin within 1 month were independent risk factors for the development of Bacillus bacteremia in adult cancer patients.

Interaction between Bacillus cereus and cultured human enterocytes: effect of calcium, cell differentiation, and bacterial extracellular factors

Bacillus cereus interaction with cultured human enterocytes and the signaling pathways responsible for the biological effects of the infection were investigated. Results demonstrate that calcium depletion increases the ability of strains T1 and 2 to invade cells. Bacteria associated in greater extent to undifferentiated enterocytes and extracellular factors from strain 2 increased its own association and invasion. Inhibitors of signaling pathways related to phosphorylated lipids (U73122 and wortmannin) were able to significantly reduce cytoskeleton disruption induced by B. cereus infection. Adhesion of strain T1 decreased in the presence of U73122 and of wortmannin, as well as when those inhibitors were used together. In contrast, invasion values were diminished only by U73122. Results show that different factors are involved in the interaction between B. cereus and cultured human enterocytes. Following infection, disruption of the cytoskeleton could facilitate invasion of the eukaryotic cells.

Meningitis due to Bacillus cereus: A case report and review of the literature

Bacillus cereus is infrequently associated with invasive central nervous system (CNS) disease. Infection is associated with conditions that lead to reduced host immunity and provide direct access to the CNS, such as spinal anesthesia and ventricular tubes and shunts. A case of ventriculitis secondary to B cereus in a patient receiving intrathecal chemotherapy is reported, along with a review of the current literature. B cereus can colonize medical devices, thus posing a risk for invasive disease. Despite aggressive treatment with broad-spectrum anti-infectives, the mortality of CNS invasive B cereus is high. Clinicians should not dismiss Gram-positive rods resembling Bacillus species from normally sterile sites as contaminants in critically ill patients. Appropriate antibiotic therapy should be promptly initiated to limit morbidity and mortality.

Bacillus cereus is infrequently associated with invasive central nervous system (CNS) disease. Infection is associated with conditions that lead to reduced host immunity and provide direct access to the CNS, such as spinal anesthesia and ventricular tubes and shunts. A case of ventriculitis secondary to B cereus in a patient receiving intrathecal chemotherapy is reported, along with a review of the current literature. B cereus can colonize medical devices, thus posing a risk for invasive disease. Despite aggressive treatment with broad-spectrum anti-infectives, the mortality of CNS invasive B cereus is high. Clinicians should not dismiss Gram-positive rods resembling Bacillus species from normally sterile sites as contaminants in critically ill patients. Appropriate antibiotic therapy should be promptly initiated to limit morbidity and mortality.

Utility of PCR amplification and DNA microarray hybridization of 16S rDNA for rapid diagnosis of bacteremia associated with hematological diseases

OBJECTIVES

The rapid diagnosis of bacteremia is crucial for patient management including the choice of antimicrobial therapy, especially in cases of hematological disease, because neutropenia occurs frequently during antineoplastic chemotherapy or disease progression. We describe a rapid detection and identification system that uses universal PCR primers to amplify a variable region of bacterial 16S ribosomal DNA (rDNA), followed by DNA microarray hybridization.

METHODS

Probes for 72 microorganisms including most causal clinical pathogens were spotted onto a microarray plate. The DNA microarray and conventional methods of identification were applied to 335 cultures from patients with hematological diseases.

RESULTS

Forty-one samples (12.2%) tested positive by conventional blood culture test in a few days, while 40 cases (11.9%) were identified by the new method within 24 h. The sensitivity and specificity of this new method were 93% and 99%, respectively, compared with conventional blood culture testing.

CONCLUSIONS

PCR combined with a DNA microarray is useful for the management of febrile patients with hematological diseases.

Bacillus cereus catheter related bloodstream infection in a patient with acute lymphoblastic leukemia

Bacillus cereus infection is rarely associated with actual infection and for this reason single positive blood culture is usually regarded as contamination . However it may cause a number of infections, such catheter-related bloodstream infections. Significant catheter-related bloodstream infections (CRBSI) caused by Bacillus spp. are mainly due to B. cereus and have been predominantly reported in immunocompromised hosts. Catheter removal is generally advised for management of infection. In this report, catheter-related bacteremia caused by B. cereus in a patient with acute lymphoblast c leukemia (ALL) in Istanbul Medical Faculty was presented.

Bacillus cereus, a volatile human pathogen

Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal non-gastrointestinal-tract infections. The pathogenicity of B. cereus, whether intestinal or nonintestinal, is intimately associated with the production of tissue-destructive exoenzymes. Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases. The major hurdle in evaluating B. cereus when isolated from a clinical specimen is overcoming its stigma as an insignificant contaminant. Outside its notoriety in association with food poisoning and severe eye infections, this bacterium has been incriminated in a multitude of other clinical conditions such as anthrax-like progressive pneumonia, fulminant sepsis, and devastating central nervous system infections, particularly in immunosuppressed individuals, intravenous drug abusers, and neonates. Its role in nosocomial acquired bacteremia and wound infections in postsurgical patients has also been well defined, especially when intravascular devices such as catheters are inserted. Primary cutaneous infections mimicking clostridial gas gangrene induced subsequent to trauma have also been well documented. B. cereus produces a potent beta-lactamase conferring marked resistance to beta-lactam antibiotics. Antimicrobials noted to be effective in the empirical management of a B. cereus infection while awaiting antimicrobial susceptibility results for the isolate include ciprofloxacin and vancomycin.

Spatial localization of bacteria controls coagulation of human blood by 'quorum acting'

Blood coagulation often accompanies bacterial infections and sepsis and is generally accepted as a consequence of immune responses. Though many bacterial species can directly activate individual coagulation factors, they have not been shown to directly initiate the coagulation cascade that precedes clot formation. Here we demonstrated, using microfluidics and surface patterning, that the spatial localization of bacteria substantially affects coagulation of human and mouse blood and plasma. Bacillus cereus and Bacillus anthracis, the anthrax-causing pathogen, directly initiated coagulation of blood in minutes when bacterial cells were clustered. Coagulation of human blood by B. anthracis required secreted zinc metalloprotease InhA1, which activated prothrombin and factor X directly (not via factor XII or tissue factor pathways). We refer to this mechanism as 'quorum acting' to distinguish it from quorum sensing--it does not require a change in gene expression, it can be rapid and it can be independent of bacterium-to-bacterium communication.

Fulminant septicemia of Bacillus cereus resistant to carbapenem in a patient with biphenotypic acute leukemia

We report a case of fulminant septicemia with Bacillus cereus resistant to carbapenem. A 33-year-old man was suffering from febrile neutropenia (FN) on day 15 after the start of remission-induction therapy for biphenotypic acute leukemia under gut decontamination with polymyxin B and nystatin. Meropenem, a carbapenem, was administered according to the guideline for FN. Two days later (on day 17), he complained of severe abdominal pain, lost consciousness, went into sudden cardiopulmonary arrest, and died. Autopsy showed multiple spots of hemorrhage and necrosis caused by bacterial plaque in the brain, lungs, and liver. B. cereus was isolated from a blood sample obtained in the morning on day 17 and it was after his death that the isolated B. cereus was revealed to be resistant to carbapenem. B. cereus obtained from blood samples has been reported to be usually sensitive to carbapenem and also to vancomycin, new quinolones, and clindamycin. If B. cereus resistant to carbapem increases, our method of gut decontamination with polymyxin B and nystatin may have to be changed to one containing a new quinolone for the prevention of septicemia. Careful watching to determine whether B. cereus resistant to carbapem increases may be also important for empiric therapy, because carbapenem is often selected as the initial therapy for FN in patients with severe neutropenia.

Bacillus cereus, the causative agent of an emetic type of food-borne illness

Bacillus cereus is the causative agent of two distinct forms of gastroenteritic disease connected to food-poisoning. It produces one emesis-causing toxin and three enterotoxins that elicit diarrhea. Due to changing lifestyles and eating habits, B. cereus is responsible for an increasing number of food-borne diseases in the industrial world. In the past, most studies concentrated on the diarrhoeal type of food-borne disease, while less attention has been given to the emetic type of the disease. The toxins involved in the diarrhoeal syndrome are well-known and detection methods are commercially available, whereas diagnostic methods for the emetic type of disease have been limited. Only recently, progress has been made in developing identification methods for emetic B. cereus and its corresponding toxin. We will summarize the data available for the emetic type of the disease and discuss some new insights in emetic strain characteristics, diagnosis, and toxin synthesis.

Bacillus cereus central line infection in an immunocompetent child with hemophilia

Bacillus species are increasingly recognized as pathogens in immunocompromised patients. The authors report a case of Bacillus cereus infection of a central line in an immunocompetent patient with hemophilia, which required line removal for complete cure.

Fatal Bacillus cereus sepsis following resolving neutropenic enterocolitis during the treatment of acute leukemia

Bacillus cereus is increasingly being acknowledged as a serious bacterial pathogen in immunosuppressed hosts. We report a case of fatal B. cereus sepsis in a patient with newly diagnosed acute leukemia following resolving neutropenic enterocolitis. Gastrointestinal complaints are common during induction chemotherapy, yet some antimicrobial coverage suitable for generalized neutropenia is not optimal for the eradication of B. cereus. This case demonstrates that, in the neutropenic patient with gastrointestinal complaints or in the setting of resolving neutropenic enterocolitis, it is important to anticipate possible B. cereus infection and sepsis.

Brain abscesses resulting from Bacillus cereus and an Aspergillus-like mold

An 11-year-old boy with alveolar rhabdomyosarcoma of the thigh experienced three instances of catheter-related bacteremia resulting from After two episodes of seizures, two low-density lesions in the right parietal lobe and the left corpus callosum with enhanced pericavitary opacity were detected. The catheter was removed. A brain biopsy sample grew and revealed dichotomously branched septate hyphae compatible with The patient was treated with ceftriaxone and liposomal amphotericin B for 12 and 52 weeks, respectively, until biopsy-confirmed resolution of the infections.

Bacillus cereus bacteremia and meningitis in immunocompromised children

Two cases of Bacillus cereus meningitis in immunocompromised children at our hospital within a 2-month period prompted us to review B. cereus--related invasive disease. We identified 12 patients with B. cereus isolated in blood cultures from September 1988 through August 2000 at our institution. Three of these patients also had B. cereus isolated from CSF specimens; 1 additional patient had possible CNS involvement (33%, group A), whereas 8 patients had no evidence of CNS involvement (67%, group B). Patients in group A were more likely to have neutropenia at the onset of sepsis and were more likely to have an unfavorable outcome. They were also more likely to have received intrathecal chemotherapy in the week before the onset of their illness. Two patients from group A died. One survived with severe sequelae. The fourth patient had mild sequelae at follow-up. No sequelae or deaths occurred among patients in group B. In patients with unfavorable outcomes, the interval from the time of recognition of illness to irreversible damage or death was short, which demonstrates a need for increased awareness, early diagnosis, and more-effective therapy, particularly that which addresses B. cereus toxins.

Bacillus cereus fatal bacteremia and apparent association with nosocomial transmission in an intensive care unit

Bacillus cereus has sometimes been implicated in food poisoning and in opportunistic infections of seriously ill patients. This report describes an unusual case of persistent bacteremia and multiple organ failure associated with B. cereus in a patient admitted to our institution for lung cancer. The patient was undergoing treatment with an antimicrobial agent (imipenem) that was shown to be effective against the micro-organism in vitro. No portal of entry for the strain was detected. After treatment with vancomycin, also shown to be effective in vitro, no clinical improvement was noted and the patient died. Molecular studies showed that the same strain caused an episode of pseudobacteremia in another patient admitted to the same ICU room.

Fulminant septicaemic syndrome of Bacillus cereus: three case reports

Three patients with acute leukaemia, who were severely neutropenic and iatrogenically immunosuppressed post-chemotherapy, developed rapidly fatal septicaemic shock and coma caused by Bacillus cereus (B. cereus). The illness was marked by two phases: a mild febrile illness lasting 6-14 h and accompanied by subtle symptoms of autonomic sympathetic nervous system overactivity, and a second short fulminant one, marked by high fever of 40-41 degrees C accompanied by major central nervous system disturbances, and ending with deep coma and brain stem dysfunction. One patient developed the sepsis in spite of 4 days of coverage with amikacin. In the other two patients, amikacin was commenced at the earliest phase of the infection, but failed to influence the outcome. This form of B. cereus sepsis in neutropenic patients seems to be caused by strains capable of causing bacteraemia and meningitis and has the ability to produce a substance that causes leptomeningeal and neuronal necrosis. Lack of early clinical and laboratory markers inevitably leads to death. Use of antibiotics effective against B. cereus and capable of achieving high concentrations in the cerebrospinal fluid. and identification and neutralization of the necrotizing substance may hopefully help to reverse this fatal illness.

Bacillus cereus causing fulminant sepsis and hemolysis in two patients with acute leukemia

PURPOSE

Hemolysis is so rarely associated with Bacillus cereus sepsis that only two very well documented cases have been reported. This article reports two unusual cases of Bacillus cereus sepsis with massive intravascular hemolysis in patients who had acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

A 20-year-old woman who was 9 weeks pregnant experienced a relapse of ALL. A therapeutic abortion was performed. During week 4 of reinduction the patient had abdominal pain, nausea, and vomiting, with severe neutropenia but no fever. Her condition deteriorated rapidly with cardiovascular collapse, acute massive intravascular hemolysis, and death within hours of the onset of symptoms. Blood cultures were positive for Bacillus cereus. Postmortem histologic examination and cultures revealed Bacillus cereus and Candida albicans in multiple organs. The second patient, a 10-year-old girl, presented with relapsed T-cell ALL. In the second week of reinduction, she had abdominal pain followed by hypotension. Again, no fever was noted. Laboratory studies showed intravascular hemolysis 12 hours after admission. Aggressive support was promptly initiated. Despite disseminated intravascular coagulation; cardiovascular, hepatic, and renal failure; and multiple intracerebral hypodense lesions believed to be infarcts, the patient recovered fully and resumed reinduction therapy.

CONCLUSIONS

Bacillus cereus infection can have a fulminant clinical course that may be complicated by massive intravascular hemolysis. This pathogen should be suspected in immunosuppressed patients who experience gastrointestinal symptoms and should not be precluded by the absence of fever, especially if steroids such as dexamethasone are being given. Exchange transfusion may be lifesaving in Bacillus cereus septicemia associated with massive hemolysis.

A novel sensitive bioassay for detection of Bacillus cereus emetic toxin and related depsipeptide ionophores

Of the toxins produced by Bacillus cereus, the emetic toxin is likely the most dangerous but, due to the lack of a suitable assay, the least well known. In this paper, a new, sensitive, inexpensive, and rapid bioassay for detection of the emetic toxin of B. cereus is described. The assay is based on the loss of motility of boar spermatozoa upon 24 h of exposure to extracts of emetic B. cereus strains or contaminated food. The paralyzed spermatozoa exhibited swollen mitochondria, but no depletion of cellular ATP or damage to plasma membrane integrity was observed. Analysis of the purified toxin by electrospray tandem mass spectrometry showed that it was a dodecadepsipeptide with a mass fragmentation pattern similar to that described for cereulide. The 50% effective concentration of the purified toxin to boar spermatozoa was 0.5 ng of purified toxin ml of extended boar semen-1. This amount corresponds to 10(4) to 10(5) CFU of B. cereus cells. No toxicity was detected for 27 other B. cereus strains up to 10(8) CFU ml-1. The detection limit for food was 3 g of rice containing 10(6) to 10(7) CFU of emetic B. cereus per gram. Effects similar to those provoked by emetic B. cereus toxin were also induced in boar spermatozoa by valinomycin and gramicidin at 2 and 3 ng ml of extended boar semen-1, respectively. The symptoms provoked by the toxin in spermatozoa indicated that B. cereus emetic toxin was acting as a membrane channel-forming ionophore, damaging mitochondria and blocking the oxidative phosphorylation required for the motility of boar spermatozoa.