Serious infections due to "non-pathogenic" organisms of the genus Bacillus. Review of their status as pathogens

Genomic versus Plasmid-Borne Expression of Germinant Receptor Proteins in Bacillus cereus Strain 14579

Germinant receptors (GRs) are proteins in the spore-forming bacteria of Bacillus species that are crucial in triggering spore germination by sensing nutrients in the spores' environment. In the Gram-positive bacterium Bacillus cereus strain ATCC 14579, the GerR GR initiates germination with L-alanine. While we have expressed GerR subunits fused to reporter proteins from genes under control of their native promoter on plasmids in this B. cereus strain, here we sought increased flexibility in this work by studying genome integration and plasmid-borne inducible high level (over) expression. However, construction of chromosomal integrants to visualize and localize the GerR B subunit fused to fluorescent reporter protein SGFP2 was not successful in this B. cereus strain using constructs with either shorter (~600 bp) or longer (~1200 bp) regions of homology to the gerR operon. This failure was in contrast to successful IPTG-inducible expression of GerRB-SGFP2 from plasmid pDG148 in vegetative cells and dormant spores, as fluorescent GerRB-SGFP2 foci were present in vegetative cells and the protein was detected by Western blot analysis. In dormant spores, the fluorescence intensity with IPTG-inducible expression from pDG148-gerRB-SGFP2 was significantly higher than in wild type spores. However, the full length GerRB-SGFP2 protein was not detected in spores using Western blots. Clearly, there are still challenges in the construction of B. cereus strains harboring fluorescent reporter proteins in which tagged proteins are encoded by genes incorporated in the chromosome or on extrachromosomal expression plasmids.

Evaluation of microbial contamination on cuff syringe, cuff pressure gauge, and their surroundings in the operating room

Background

Some institutions reuse cuff syringes and do not periodically sterilize cuff pressure gauges. Pathogenic bacterial contamination of such equipment may increase the probability of pathogen transmission to patients during anesthetic procedures. Therefore, microbial contamination on cuff syringes, cuff pressure gauges, and their surroundings was assessed in the operating rooms of a university-affiliated tertiary care hospital in Japan.

Methods

This study was conducted between April and May 2019 in 14 operating suites at a hospital. The following sites in each operating suite were sampled: cuff syringe (inner/outer components), outer components of cuff pressure gauge, cuff syringe and cuff pressure gauge storage drawers, and computer mice. The swabs were directly streaked onto agar plates and incubated. Then, the bacterial species were identified using mass spectrometry.

Results

The highest bacterial isolation was observed in computer mice, followed by the outside of cuff pressure gauges and the drawers of cuff pressure gauges (92.9, 78.6, and 64.3%, respectively). Most of the identified bacteria belonged to the Bacillus species, with colonization rates of 85.7, 57.1, and 57.1% on computer mice, cuff pressure gauges, and cuff pressure gauge storage drawers, respectively. Coagulase-negative Staphylococcus was found in 35.7% of the specimens and was more prevalent on computer mice (71.4%), followed by on cuff pressure gauges (64.3%).

Conclusion

Anesthesiologists should be aware of the possible pathogen contamination risk from cuff syringes, cuff pressure gauges, or associated equipment and take appropriate infection control measures to minimize the risk of pathogenic transmission.

Investigation of a cluster of Bacillus cereus bacteremia in neonatal care units

BACKGROUND

Bacillus cereus is a well-known pathogen for self-limited foodborne illness, and rarely an opportunistic pathogen associated with invasive infections among immunocompromised patients. Nosocomial outbreaks have been rarely reported.

METHODS

Between August and November 2019, four preterm neonates in neonatal care units of a medical center developed late-onset B. cereus bacteremia. An investigation was carried out. Forty-eight environmental specimens were obtained from these neonatal units, skin surface and environmental objects of Patient 4 for the detection of this organism 19 days after the onset of illness of Patient 4. B. cereus isolates from Patient 4, five unrelated patients and environmental objects if identified were further characterized by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

RESULTS

All four infants survived after vancomycin-containing treatment. Patient 4 developed diffuse cerebritis, brain abscess with severe neurologic sequelae. Of the 48 environmental samplings, 26 specimens showed positive for B. cereus, with one major clone (sequence type 365) accounting for 73%. The isolate from Patient 4 (ST427) was identical to one isolate collected from environmental objects in the same unit. After extensive cleaning of the environment and re-institution of the sterilization procedure of hospital linens, which was ceased since two months before the outbreak, no more cases was identified in these units for at least one year.

CONCLUSIONS

We documented a cluster of B. cereus bacteremia involving four preterm infants, which might be associated with cessation of the procedure for linen sterilization and was successfully controlled by re-institution of this procedure.

A rare case of Bacillus megaterium soft tissues infection

Background and aim of the work:

To report the history and clinical presentation of a 60-year-old male who developed a rare soft tissue infection of the right leg caused by Bacillus megaterium and to perform a Literature review focusing on clinical manifestations and diagnostic difficulties of the aforementioned bacterium.

Methods:

Medical history and clinical presentation suggested the infectious etiology, which led to the surgical procedure of fistulectomy and to further histological and microbiological investigations with bacterial cultures.

Results:

The histological report tested negative for osteomyelitis. Bacterial cultures revealed Bacillus megaterium, which was sensitive to all antibiotics against which it was tested. The oral antibiotic therapy was set for 12 days with benefits. The patient has always been apyretic, inflammation indexes and white cells count have been within normal limits.

Conclusions:

This was a rare case of soft tissue infection caused by Bacillus megaterium known to be a “non-pathogenic” bacterium. The infection was likely acquired by the penetration through the injury wound. The combination of surgical and antibiotic therapy lead to complete skin healing and infection resolution at the 6-months follow up.

Bacillus cereus: Epidemiology, Virulence Factors, and Host-Pathogen Interactions

The toxin-producing bacterium Bacillus cereus is an important and neglected human pathogen and a common cause of food poisoning. Several toxins have been implicated in disease, including the pore-forming toxins hemolysin BL (HBL) and nonhemolytic enterotoxin (NHE). Recent work revealed that HBL binds to the mammalian surface receptors LITAF and CDIP1 and that both HBL and NHE induce potassium efflux and activate the NLRP3 inflammasome, leading to pyroptosis. These mammalian receptors, in part, contribute to inflammation and pathology. Other putative virulence factors of B. cereus include cytotoxin K, cereulide, metalloproteases, sphingomyelinase, and phospholipases. In this review, we highlight the latest progress in our understanding of B. cereus biology, epidemiology, and pathogenesis, and discuss potential new directions for research in this field.

Antibiotic resistance and inhibition mechanism of novel aminoglycoside phosphotransferase APH(5) from B. subtilis subsp. subtilis strain RK

Bacterial resistance towards aminoglycoside antibiotics mainly occurs because of aminoglycoside phosphotransferases (APHs). It is thus necessary to provide a rationale for focusing inhibitor development against APHs. The nucleotide triphosphate (NTP) binding site of eukaryotic protein kinases (ePKs) is structurally conserved with APHs. However, ePK inhibitors cannot be used against APHs due to cross reactivity. Thus, understanding bacterial resistance at the atomic level could be useful to design new inhibitors against such resistant pathogens. Hence, we carried out in vitro studies of APH from newly deposited multidrug-resistant organism Bacillus subtilis subsp. subtilis strain RK. Enzymatic modification studies of different aminoglycoside antibiotics along with purification and characterization revealed a novel class of APH, i.e., APH(5), with molecular weight 27 kDa approximately. Biochemical analysis of virtually screened inhibitor ZINC71575479 by coupled spectrophotometric assay showed complete enzymatic inhibition of purified APH(5). In silico toxicity study comparison of ZINC71575479 with known inhibitor of APH, i.e., tyrphostin AG1478, predicted its acceptable values for 96 h fathead minnow LC₅₀, 48 h Tetrahymena pyriformis IGC₅₀, oral rat LD₅₀, and developmental toxicity using different QSAR methodologies. Thus, the present study gives novel insight into the aminoglycoside resistance and inhibition mechanism of APH(5) by applying experimental and computational techniques synergistically.

Metagenomic analysis of tarball-associated bacteria from Goa, India

The beaches of Goa state in India are frequently polluted with tarballs, specifically during pre-monsoon and monsoon seasons. Tarballs contain hydrocarbons, including polycyclic aromatic hydrocarbons, which pose significant environmental risks. Microbes associated with tarballs reportedly possess capabilities to degrade toxic hydrocarbons present in tarballs. In this study, bacterial diversity associated with tarballs from Vagator and Morjim beaches of north Goa was analysed based on V3-V4 regions of 16S rRNA gene sequenced using Illumina Miseq Platform. The Proteobacterial members were dominant in both Vagator (≥85.5%) and Morjim (≥94.0%) samples. Many of the identified taxa have been previously reported as hydrocarbon degraders (e.g. Halomonas, Marinobacter) or possible human pathogens (e.g. Acinetobacter, Klebsiella, Rhodococcus, Staphylococcus, Vibrio). This is the first study reported on a metagenomic analysis of bacteria associated with tarballs from Goa.

Spontaneous cerebral abscess due to Bacillus subtilis in an immunocompetent male patient: A case report and review of literature

BACKGROUND

Bacillus subtilis (B. subtilis) is considered a non-pathogenic microorganism of the genus Bacillus and a common laboratory contaminant. Only scarce reports of B. subtilis central nervous system infection have been reported, mainly in the form of pyogenic meningitis, usually in cases of direct inoculation by trauma or iatrogenically.

CASE SUMMARY

A 51-year-old man, with a free previous medical history, presented to the Emergency Department of our hospital complaining of recurrent episodes of left upper limb weakness, during the last month, which had been worsened the last 48 h. During his presentation in Emergency Department he experienced a generalized tonic-clonic grand mal seizure. Brain magnetic resonance imaging (MRI) scan with intravenous Gadolinium revealed a 3.3 cm × 2.7 cm lesion at the right parietal lobe surrounded by mild vasogenic edema, which included the posterior central gyrus. The core of the lesion showed relatively homogenous restricted diffusion. Post Gadolinium T1W1 image, revealed a ring-shaped enhancement. Due to the imaging findings, brain abscess was our primary consideration. Detailed examination for clinical signs of infectious foci revealed only poor oral hygiene with severe tooth decay and periodontal disease, but without detection of dental abscess. The patient underwent surgical treatment with right parietal craniotomy and total excision of the lesion. Pus and capsule tissue grew B. subtilis and according to antibiogram intravenous ceftriaxone 2 g bids was administered for 4 wk. The patient remained asymptomatic and follow-up MRI scan two months after operation showed complete removal of the abscess.

CONCLUSION

This case highlights the ultimate importance of appropriate oral hygiene and dental care to avoid potentially serious infectious complications and second, B. subtilis should not be considered merely as laboratory contaminant especially when cultivated by appropriate central nervous system specimen.

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.

Infective endocarditis due to Bacillus cereus in a pregnant female: A case report and literature review

Incidence of infective endocarditis during pregnancy is around 0.006% with high maternal and fetal mortality. Bacillus cereus is an extremely rare cause for endocarditis in intravenous drug abusers (IVDA) or those with valvular disease or devices such as pacemakers. We report a case of B. cereus endocarditis, which, to the best of our knowledge, has never been reported in pregnancy. A 30-year-old, 25-week pregnant female presented with right shoulder pain, swelling and erythema on the lateral aspect of deltoid muscle from large abscess over her deltoid muscle. She was found to have a vegetation on the native tricuspid valve. Cultures from abscess fluid and blood cultures grew B. cereus, she was appropriately treated with antimicrobials and had favorable outcomes. There are <20 cases of B. cereus endocarditis reported but none during pregnancy. When cultures grow unusual organisms the case must be thoroughly investigated. This case illustrates a rare situation (endocarditis in pregnancy) with an unusual outcome (B. cereus) on an uncommon valve (tricuspid valve).

Isolation and Characterization of Phages Infecting Bacillus subtilis

Bacteriophages have been suggested as an alternative approach to reduce the amount of pathogens in various applications. Bacteriophages of various specificity and virulence were isolated as a means of controlling food-borne pathogens. We studied the interaction of bacteriophages with Bacillus species, which are very often persistent in industrial applications such as food production due to their antibiotic resistance and spore formation. A comparative study using electron microscopy, PFGE, and SDS-PAGE as well as determination of host range, pH and temperature resistance, adsorption rate, latent time, and phage burst size was performed on three phages of the Myoviridae family and one phage of the Siphoviridae family which infected Bacillus subtilis strains. The phages are morphologically different and characterized by icosahedral heads and contractile (SIOΦ, SUBω, and SPOσ phages) or noncontractile (ARπ phage) tails. The genomes of SIOΦ and SUBω are composed of 154 kb. The capsid of SIOΦ is composed of four proteins. Bacteriophages SPOσ and ARπ have genome sizes of 25 kbp and 40 kbp, respectively. Both phages as well as SUBω phage have 14 proteins in their capsids. Phages SIOΦ and SPOσ are resistant to high temperatures and to the acid (4.0) and alkaline (9.0 and 10.0) pH.

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.

Combined Bacillus licheniformis and Bacillus subtilis infection in a patient with oesophageal perforation

Species of the genus Bacillus are a common laboratory contaminant, therefore, isolation of these organisms from blood cultures does not always indicate infection. In fact, except for Bacillus anthracis and Bacillus cereus, most species of the genus Bacillus are not considered human pathogens, especially in immunocompetent individuals. Here, we report an unusual presentation of bacteraemia and mediastinitis due to co-infection with Bacillus subtilis and Bacillus licheniformis, which were identified by 16S RNA gene sequencing, in a patient with an oesophageal perforation.

Bacillus species infective arthritis after knee arthroscopy

BACKGROUND

Bacillus species infection of the joints is a very rare occurrence, with sporadic reports in the medical literature.

CASE REPORT

A 67-year-old woman with osteoarthritis developed infection in the knee joint after arthroscopy. Percutaneous needle aspiration of articular fluid performed post-operatively showed a positive culture for Bacillus species. The diagnosis of septic arthritis was, however, not confirmed as the results were considered contamination. Failure of treatment with beta-lactam antibiotics on two occasions and successful cure of infective arthritis by long-term administration of a fluoroquinolone confirmed iatrogenic clinical joint infection with Bacillus species.

CONCLUSION

Any clinically suspected joint infection must be treated as septic arthritis until proved otherwise.

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.

Liver abscess and sepsis with Bacillus pantothenticus in an immunocompetent patient: A first case report

Bacillus species are aerobic, gram-positive, spore forming rods that are usually found in the soil, dust, streams, and other environmental sources. Except for Bacillus. anthracis (B. anthracis), most species display low virulence, and only rarely cause infections in hosts with weak or damaged immune systems. There are two case reports of B. cereus as a potentially serious bacterial pathogen causing a liver abscess in an immunologically competent patient. We herein report a case of liver abscess and sepsis caused by B. pantothenticus in an immunocompetent patient. Until now, no case of liver abscess due to B. pantothenticus has been reported.

Control of insects by bacteria

All bacteria in microbial insecticides are species ofBacillusand form spores since they have to survive in the environment and on the shelf. They can be formulated as wettable powders, suspensions and dusts for application with conventional pest control machinery. All are safe to man and virtually all non-target organisms. Development costs are relatively low, but host specificity greatly restricts markets, the largest beingca. 2000 tons per annum in the West forB. thuringiensis. All act only after ingestion, a disadvantage because there is no contact action and usually only larvae are attacked. Three main groups have special features that determine their commercial success.

TheB. popilliaegroup is produced onlyin vivowhich limits production by three small firms. The Japanese beetle has been controlled in grassland in the warm parts of the USA by single applications of spores in heaps, spaced 2 m each way. The bacterium spreads slowly to untreated areas, is very persistent and kills only by infection.

TheB. thuringiensisgroup kills larvae of Lepidoptera, mosquitoes and blackflies, mainly by gut poisoning with a protein crystal toxin. It rapidly paralyses mouthparts and gut, stopping crop damage. It is readily produced by deep liquid fermentation, but does not persist and needs repeated application during the pest season. Products containing no beta exotoxin can be applied at unlimited dosage to food crops up to harvest. Only one application is needed for stored grain. After 20 years' use of strains against Lepidoptera, a different strain is now used commercially against mosquitoes and blackflies (only 5 years after its discovery), although improvements in formulation for aquatic application are needed. A recent new product based on the beta exotoxin is used in Finland only against flies in pig houses because it has some vertebrate toxicity.

TheB. sphaericusgroup is similar toB. thuringiensis, except that its proteinaceous toxin is different, is situated in the spore wall in strain 1593, and attacks only mosquitoes. Now at the pilot production stage, its commercial future depends on whether it is more potent thanB. thuringiensisagainst certain species and whether it can recycle to give effective extended mosquito control in some environments.

Intensive selection from natural isolates has improved potency 100 to 600 fold. This selective effort must be maintained and improved by genetic manipulation, which can be used to develop greater potential, particularly since DNA coding for the crystal toxin is carried on plasmids. This also gives speculative hope that the toxin may be incorporated into natural aquatic bacteria for mosquito control and into plants for protection against lepidopterous larvae. A great advantage is that these bacteria do not harm beneficial fauna to cause pest resurgence. At present, the main use lies in integrated pest control systems, although bacteria are not likely to supplant chemical insecticides on a large scale in the near future.

Central venous catheter infection with Bacillus pumilus in an immunocompetent child: a case report

BACKGROUND

Bacillus organisms are common laboratory contaminants. The majority of Bacillus bacteraemias are transient and not clinically significant. Clinically significant infection due to Bacillus species is rare and mostly due to Bacillus cereus infections in immuno-compromised hosts.

CASE PRESENTATION

We report a case of central venous catheter infection with Bacillus pumilus in an immunocompetent child with tufting enteropathy on long-term parenteral nutrition (PN). There were three episodes of central venous catheter infection with Bacillus pumilus in three months. Despite adequate and appropriate use of intravenous antibiotics, the infection failed to clear resulting in the need for removal of the catheter for complete cure.

CONCLUSION

Bacillus species can cause clinically significant central venous catheter infection, even in an immunocompetent host. Despite adequate antibiotic treatment, the central venous catheter may need removal for complete cure.

Bacillus cereus: The Forgotten Pathogen

BACKGROUND

Infection with Bacillus cereus is generally associated with gastrointestinal effects of food poisoning linked to infected rice. Isolates of B. cereus in hospital and clinical settings from any material other than vomitus or feces are commonly dismissed as contaminants.

CASE REPORT

We report a case of B. cereus surgical site infection after fasciotomy in a healthy 31 year-old man admitted to the orthopedic ward with a comminuted fracture of the tibia. No source was identified.

CONCLUSIONS

This report highlights the risk of surgical site infection with an unlikely bacterium known to contaminate surgical materials. It stresses the importance of vigilance against this infrequent but potentially serious non-gastrointestinal bacillary infection, as organisms dismissed initially as contaminants may lead to rapid clinical deterioration. The use of antimicrobial agents with nosocomial coverage, even of non-nosocomial pathogens, is considered in the treatment of postoperative surgical site infections.

Fate and dissemination of Bacillus subtilis spores in a murine model

Bacterial spores are being consumed as probiotics, although little is known about their efficacy or mode of action. As a first step in characterizing spore probiotics, we have studied the persistence and dissemination of Bacillus subtilis spores given orally to mice. Our results have shown that spores do not appear to disseminate across the mucosal surfaces. However, we found that the number of spores excreted in the feces of mice was, in some experiments, larger than the original inoculum. This was an intriguing result and might be explained by germination of a proportion of the spore inoculum in the intestinal tract, followed by limited rounds of cell growth and then sporulation again. This result raises the interesting question of whether it is the spore or the germinated spore that contributes to the probiotic effect of bacterial spores.

Clinical manifestations of Bacillus cereus meningitis in newborn infants

Bacillus cereus (B. cereus) meningitis sometimes occurs in patients with risk factors, which are associated with central nervous system (CNS) anomalies, surgical or anaesthetic access to CNS. We observed two cases of B. cereus meningitis in neonates without such risk factors. The clinical courses of both neonates were fulminant, and routine antibiotic therapy failed. Intracranial haemorrhage was evident at autopsy. According to the previous neonatal case reports and our experience, we found that six of seven neonates were premature babies admitted to the neonatal intensive care unit, five died within a week of onset of the disease, and six had intracranial haemorrhage. We speculate that B. cereus meningitis may occur in neonates, even without any of the risk factors previously described in adult case reports, and that the clinical manifestations of the meningitis might be characterized by the high incidence of intracranial haemorrhage and poor mortality.

Bacillus cereus infections among oncology patients at a children's hospital

BACKGROUND

Bacillus cereus can cause severe infections in immunocompromised persons.

METHODS

We report 3 cases of bacteremia/septicemia (1 fatal) among oncology patients in a children's hospital. Because all cases occurred during a 10-day period, a common source outbreak was suspected. An epidemiologic investigation was performed. Molecular comparison of patient and environmental isolates was performed by using pulsed-field gel electrophoresis.

RESULTS

After an extensive investigation, no common hospital source could be found. Pulsed-field gel electrophoresis proved that the isolates were not related.

CONCLUSION

Sporadic infections in immunocompromised persons do occur and can be associated with significant morbidity.

Bacillus cereus prosthetic valve endocarditis

Bacillus cereus is a ubiquitous organism that often contaminates microbiological cultures but rarely causes serious infections. Reports of B. cereus endocarditis are infrequent. Infection in patients with valvular heart disease is associated with significant mortality and morbidity. We describe a case of B. cereus endocarditis involving a mechanical mitral prosthesis that resolved after replacement of the prosthetic valve. We also review the previous cases reported in the literature.

beta-Hemolytic streptococci and other beta-hemolytic organisms in apical periodontitis and severe marginal periodontitis

Thirteen teeth with necrotic pulps and apical periodontitis and nine severe periodontal pockets were cultured for presence of beta-hemolytic streptococci and other beta-hemolytic organisms. Samples were dispersed and plated on two non-selective and one selective growth media and incubated anaerobically and in 10% CO2 in air. A total of 59 beta-hemolytic colonies were purified and identified. Eight beta-hemolytic streptococcal isolates were obtained from three of the severe marginal periodontitis sites. All were identified as belonging to the Streptococcus sanguis group. No beta-hemolytic streptococci were detected in apical periodontitis samples. Twenty obligately anaerobic isolates were detected, all of which were known periodontal and endodontic pathogens. Isolates from apical periodontitis sites were identified as Propionibacterium acnes, Actinomyces naeslundii, Actionomyces odontolyticus and Peptostreptococcus micros, while severe marginal periodontal sites contained the same species with the addition of Actinomyces viscosus and Actinomyces meyeri. Of 19 staphylococci and micrococci, Staphylococcus epidermidis was the predominant isolate in both apical periodontitis and severe marginal periodontitis sites. However, less commonly known organisms such as Staphylococcus cohnii and Micrococcus sp. were identified in severe marginal periodontitis sites. The isolation of Bacillus sp. (12 isolates) in one severe marginal periodontitis and two apical periodontitis subjects was especially interesting, warranting consideration of this organism as a legitimate isolate and potential pathogen in oral disease.

Infection with Bacillus cereus after close-range gunshot injuries

Three patients were admitted with close-range gunshot wounds of the knee and lower leg, inflicted in all three cases through clothing. At admission, all of the patients were given antibiotics (cefuroxime and metronidazole) to prevent streptococcal and anaerobic infection. All of the patients developed severe tissue infection with Bacillus cereus within days of admission. In one case, the organism was also recovered from the blood. B. cereus is capable of causing severe infection after trauma and its ubiquity in the environment allows it easy access to gunshot wounds. Its potent production of beta-lactamase renders penicillins and cephalosporins predictably ineffective. The early administration of a non-beta-lactam drug (such as ciprofloxacin) should be considered in cases where Bacillus cereus is isolated from traumatic wounds.

Brain abscess due to Bacillus macerans following a penetrating periorbital injury

We report a case of a brain abscess due to Bacillus macerans and Clostridium sp. following a penetrating periorbital injury by a wooden branch. Intracranial penetration by and retention of a foreign body were not suspected initially, and neurological symptoms developed only 2.5 months later. Previously reported cases of brain abscesses due to Bacillus species are reviewed.

Recovery of uncommon bacteria from blood: association with neoplastic disease

Table 6 is a summary of the organisms discussed with a listing of the environmental source, the endogenous source, the predisposing factors including neoplasms, and the postulated mechanisms by which the organism can gain access to the circulation. The evidence considered indicates that the entrance of one of these microorganisms into the bloodstream of a human being depends on the presence of multiplicity of predisposing factors. In the majority of cases of bacteremia due to one of these unusual organisms, two or more predisposing factors are present. Certain predisposing factors, such as cancer chemotherapy or intravenous catheterization, often provide a barrier break, while others, such as liver disease, may render the host immune system less capable of clearing organisms from the circulation. For organisms such as Campy-lobacter, Listeria, and Salmonella spp., attributes that allow the invasion of a healthy host are present and seem to be enhanced by the simultaneous presence of a predisposing condition, such as liver disease, in the host. Although somewhat fragmentary, a number of individual case reports describe bacteremia due to one of these organisms occurring weeks to years after surgery and after other therapeutic measures had effected a supposed cure of a cancer. It may be speculated that cancer patients, even after a cure, are still susceptible to bloodstream invasion by one of the aforementioned organisms by virtue of the presence of one or more predisposing metabolic, physiologic, or immunologic factors, even though these factors may be cryptic. The predominance of hematologic malignancies among cases of bacteremia due to these unusual organisms is also apparent. Although, as pointed out by Keusch (169), the reduction in the performance of immune function in hematologic malignancies compared with solid tumors is likely to be responsible, other associations of certain organisms with specific neoplasms warrant further examination. The frequency of bloodstream infections of Salmonella typhimurium and Capno-cytophaga canimorsus in Hodgkin's disease patients seems likely due to a particular mechanism which infection by these species is favored. The specific nature of these mechanisms remains to be determined. The recovery of any unusual bacterium from blood should warrant a careful consideration of the possibility of underlying disease, especially cancer. Microbiologists should advise clinicians of the unusual nature of the identified organism and provide the counsel that certain neoplastic processes, often accompanied by neutropenia, render the human host susceptible to invasion by almost any bacterium. The recovery of such organisms as C. septicum or S. bovis should prompt the clinician to aggressively seek to identify an occult neoplasm if one has not yet been diagnosed.

The management of impalement injury

Four cases of impalement injury are described. The principles of management are discussed, these being minimal manipulation of the object before and during transport, preoperative planning, a multidisciplinary approach, and wound care.

Bacillus cereus and related species

Bacillus cereus is a gram-positive aerobic or facultatively anaerobic spore-forming rod. It is a cause of food poisoning, which is frequently associated with the consumption of rice-based dishes. The organism produces an emetic or diarrheal syndrome induced by an emetic toxin and enterotoxin, respectively. Other toxins are produced during growth, including phospholipases, proteases, and hemolysins, one of which, cereolysin, is a thiol-activated hemolysin. These toxins may contribute to the pathogenicity of B. cereus in nongastrointestinal disease. B. cereus isolated from clinical material other than feces or vomitus was commonly dismissed as a contaminant, but increasingly it is being recognized as a species with pathogenic potential. It is now recognized as an infrequent cause of serious nongastrointestinal infection, particularly in drug addicts, the immunosuppressed, neonates, and postsurgical patients, especially when prosthetic implants such as ventricular shunts are inserted. Ocular infections are the commonest types of severe infection, including endophthalmitis, panophthalmitis, and keratitis, usually with the characteristic formation of corneal ring abscesses. Even with prompt surgical and antimicrobial agent treatment, enucleation of the eye and blindness are common sequelae. Septicemia, meningitis, endocarditis, osteomyelitis, and surgical and traumatic wound infections are other manifestations of severe disease. B. cereus produces beta-lactamases, unlike Bacillus anthracis, and so is resistant to beta-lactam antibiotics; it is usually susceptible to treatment with clindamycin, vancomycin, gentamicin, chloramphenicol, and erythromycin. Simultaneous therapy via multiple routes may be required.

Bacillus species pseudobacteremia traced to contaminated gloves used in collection of blood from patients with acquired immunodeficiency syndrome

Ten nonpathogenic Bacillus isolates were obtained from blood cultures collected over a 2-year period. Eight of these isolates were from patient with acquired immunodeficiency syndrome, and seven were recovered from blood cultures obtained in outpatient clinics. Five cases occurred during a 5-month period. These five cases were clinically evaluated, and the Bacillus isolates were characterized. The same Bacillus species was isolated from nonsterile gloves from the same lot worn by phlebotomists for blood collection in the outpatient clinics during this period, implicating the gloves as the cause of this pseudoepidemic. Awareness of the nonsterile nature of gloves used by laboratory personnel should be considered in the evaluation of Bacillus spp. in blood cultures.

Bacteremia and infection of a hip prosthesis caused by Bacillus alvei

Of the 34 Bacillus species described, 10 have been reported to cause infection in humans and 6 are insect pathogens. We report a case of an infected prosthetic hip caused by Bacillus alvei, only the third documented case of human infection with this organism.

Nosocomial bacteremia caused by Bacillus species

During a six year period, 11 cases of bacteremia caused by Bacillus spp. were observed corresponding to 1% of all bacteremic episodes in our hospital. Most patients had cancer as underlying disease. All cases of positive blood cultures were associated with a clinical syndrome compatible with sepsis including high fever. None of the subsequent deaths could be related to the bacteremia caused by Bacillus spp. Four of eight cases of Bacillus subtilis bacteremia were associated with the absorption of an oral preparation containing Bacillus subtilis spores, which was administered empirically in some units of the hospital to reduce what was considered to be tube-feeding related diarrhea.

Bacillus species

The genus Bacillus is a diverse group of gram-positive, spore-forming aerobic bacilli. B anthracis, the agent of anthrax, is primarily an animal pathogen but is capable of causing human infection, most commonly of the skin or lungs. B cereus, a well-recognized cause of gastroenteritis, may occasionally cause epidemics in health institutions. Both B cereus and other Bacillus species are increasingly recognized as opportunistic pathogens in the hospitalized patient. This report is intended as a comprehensive review of the bacteriology, clinical features, and therapy of Bacillus spp infections. Nosocomial epidemics and transmission will be highlighted.

In vitro susceptibility of Bacillus spp. to selected antimicrobial agents

Although often dismissed as contaminants when isolated from blood cultures, Bacillus spp. are increasingly recognized as capable of causing serious systemic infections. As part of a clinical-microbiological study, 89 strains of Bacillus spp. isolated from clinical blood cultures between 1981 and 1985 had their species determined and were tested for antimicrobial agent susceptibility to 18 antibiotics. Species of isolates were determined by the API 50CH and API 20E systems. Bacillus cereus (54 strains) was the most common species isolated, followed by B. megaterium (13 strains), B. polymyxa (5 strains), B. pumilus (4 strains), B. subtilis (4 strains), B. circulans (3 strains), B. amyloliquefaciens (2 strains), B. licheniformis (1 strain), and Bacillus spp. (3 strains). Microdilution MIC susceptibility tests revealed all B. cereus strains to be susceptible to imipenem, vancomycin, chloramphenicol, gentamicin, and ciprofloxacin. Non-B. cereus strains were most susceptible to imipenem, vancomycin, LY146032, and ciprofloxacin. Disk susceptibility testing suggested that B. cereus was rarely susceptible to penicillins, semisynthetic penicillins, or cephalosporins with the exception of mezlocillin. In contrast, many non-B. cereus strains were susceptible to penicillins, semisynthetic penicillins, and cephalosporins, but marked variability was noted among species.

Clinical features and therapeutic interventions in 17 cases of Bacillus bacteremia in an immunosuppressed patient population

We retrospectively examined episodes of Bacillus bacteremia at a hospital with a large proportion of immunosuppressed patients. Seventeen episodes in 9.5 years met our case definition: two of two bottles of one blood culture or one of two bottles of two or more separately obtained blood cultures drawn on the same date. During the same period, there were 59 additional episodes in which a single blood culture had only one of two bottles positive for Bacillus species. Only 2 of 59 such episodes resulted in recurrent bacteremia (3%), as compared with 5 of 17 episodes meeting our case definition (29%) (P = 0.004). In four of five episodes complicated by recurrent bacteremia and in which appropriate antibiotics were used, a Hickman-Broviac catheter was in place and was not removed. We suggest that our case definition permits the differentiation of infection from contamination based on outcome and that patients with Bacillus bacteremia have chronic venous catheters removed as well as receive antibiotic treatment.

Methods for distinguishing gram-positive from gram-negative bacteria

Lysis by KOH and hydrolysis of L-alanine-4-nitroanilide were compared with the Gram reaction of aerobic, microaerophilic, and anaerobic bacteria. Both tests correlated well with the Gram reaction with nonfermentative bacilli and Bacillus species, whereas they did not correlate with nonsporulating anaerobes. Only campylobacteria were KOH positive and L-alanine-4-nitroanilide and gram negative.

Fulminating panophthalmitis due to exogenous infection with Bacillus cereus: report of 4 cases

Bacillus cereus is a seldom recognised but important cause of panophthalmitis. Although most reported cases have been the result of endogenous infection, we have recently seen 4 cases that followed ocular trauma. In each instance a fulminating panophthalmitis developed, accompanied by fever and leucocytosis. Despite prompt therapy all eyes were rapidly lost. In view of the selective antibiotic sensitivities of this organism and the fulminating course of the disease, conventional approaches to therapy, including standard prophylactic antibiotic regimens, are unlikely to be successful in such cases. Analysis of our cases suggest that ocular infection with B. cereus has certain features that may allow a provisional diagnosis to be made before isolation of the organism. Early recognition and prompt institution of effective therapy may lead to salvage of these eyes in the feature.