Changes in mitochondrial perilipin 3 and perilipin 5 protein content in rat skeletal muscle following endurance training and acute stimulated contraction

NEW FINDINGS

What is the central question of this study? The aim was to determine whether mitochondrial protein content of perilipin 3 (PLIN3) and perilipin 5 (PLIN5) is increased following endurance training and whether mitochondrial PLIN5 protein is increased to a greater extent in endurance-trained rats when compared with sedentary rats following acute contraction. What is the main finding and its importance? Mitochondrial PLIN3 but not PLIN5 protein was increased in endurance-trained compared with sedentary rats, suggesting a mitochondrial role for PLIN3 due to chronic exercise. Contrary to our hypothesis, acute mitochondrial PLIN5 protein was similar in both sedentary and endurance-trained rats. Endurance training results in an increased association between skeletal muscle lipid droplets and mitochondria. This association is likely to be important for the expected increase in intramuscular fatty acid oxidation that occurs with endurance training. The perilipin family of lipid droplet proteins, PLIN(2-5), are thought to play a role in skeletal muscle lipolysis. Recently, results from our laboratory demonstrated that skeletal muscle mitochondria contain PLIN3 and PLIN5 protein. Furthermore, 30 min of stimulated contraction induces an increased mitochondrial PLIN5 content. To determine whether mitochondrial content of PLIN3 and PLIN5 is altered with endurance training, Sprague-Dawley rats were randomized into sedentary or endurance-trained groups for 8 weeks of treadmill running followed by an acute (30 min) sciatic nerve stimulation to induce lipolysis. Mitochondrial PLIN3 protein was ∼1.5-fold higher in red gastrocnemius of endurance-trained rats compared with sedentary animals, with no change in mitochondrial PLIN5 protein. In addition, there was an increase in plantaris intramuscular lipid storage. Acute electrically stimulated contraction in red gastrocnemius from sedentary and endurance-trained rats resulted in a similar increase of mitochondrial PLIN5 between these two groups, with no net change in PLIN3 in either group. Plantaris intramuscular lipid content decreased to a similar extent in sedentary and endurance-trained rats. These results suggest that while total mitochondrial PLIN5 content is not altered by endurance training, PLIN5 does have an acute role in the mitochondrial fraction during muscle contraction. Conversely, mitochondrial PLIN3 does not change acutely with muscle contraction, but PLIN3 content was increased following endurance training, indicating a role in chronic adaptations of skeletal muscle.

Passive transfer of protection against Bacillus anthracis infection in a murine model

Passive transfer of lymphocytes and sera from mice immunised using two different formulations containing recombinant protective antigen (rPA) have been used to further elucidate the mechanism of protection against Bacillus anthracis infection. The results demonstrated that an antibody response maybe important in protection against B. anthracis infection, under the conditions tested. The results provide further data for the development of an improved anthrax vaccine.

Human immune responses to the UK human anthrax vaccine

The IgG anti-protective antigen subclass antibody response of individuals who had been infected with anthrax was compared with that of healthy individuals immunized with the UK licensed anthrax vaccine. The predominant subclass in both groups was IgG1. In addition, IgG3 was seen in convalescent serum while vaccinees produced IgG2, IgG3 and IgG4 subclass. The significance of these results is discussed. Further work is required to determine the role of antibodies in mediating protective immunity in man.

Immune correlates of protection against anthrax

Bacillus anthracis protective antigen (PA) has been produced from a recombinant B. subtilis and its efficacy, when combined with the Ribi adjuvant (MPL-TDW-CWS) or alhydrogel, has been compared with that of the licensed UK human vaccine, in guinea pigs challenged with aerosolized Ames strain spores. Recombinant PA combined with the Ribi adjuvant performed as well as PA from B. anthracis cultures in previous reports (Ivins & Welkos 1986; Ivins et al. 1990; Turnbull et al. 1991; Jones et al. 1996; McBride et al. 1998) giving protection in 100% of animals exposed to the highest challenge dose of the Ames strain of B. anthracis that can be administered practically (retained lung doses of approximately 106 spores). In attempts at identifying markers of protection in immunized individuals, rPA in combination with the Ribi adjuvant induced a marker IgG2 response in guinea pigs with no significant differences in IgG1 levels when compared with other vaccine formulations (McBride et al. 1998). In BALBc mice, rPA with the Ribi adjuvant induced a higher IgG2a response compared with rPA with anhydrogel and the human vaccine. To examine the role of anti-PA-specific antibodies in protection, guinea pig sera is being passively transferred into guinea pigs and SCID mice, followed by protection. Similarly, B- and T-lymphocytes from immunized BALB/c mice are being separately and passively transferred into SCID mice with subsequent challenge. The neutralizing ability of the PA-specific antibodies is being studied using an in vitro macrophage lysis assay.

Definitive identification of Bacillus anthracis--a review

The word 'problem' is seen with some frequency in relation to clear differentiation between Bacillus anthracis and B. cereus. In fact, although the close relationship of these two species is undisputed, it is only in the case of a few borderline isolates, rarely encountered in practice, that any sort of identification problem exists. Until recently this was only important to the taxonomist who found it unsatisfactory not to be able to identify definitively such isolates. To most others, if the isolate was unable to produce anthrax in a laboratory animal, it was discarded as irrelevant without being named, or it was called B. cereus or given a name such as B. anthracis similis, or even a totally unrelated name. More recently, in view of the new light in which B. anthracis is increasingly seen, resulting from its putative association with bioaggression, clear identification has become a more critical issue. This paper reviews the current state of the art and suggests the way forward for the future.

World Health Organization activities on anthrax surveillance and control

The achievements of a World Health Organization Anthrax Working Group, established in 1990, have been the production of two editions of guidelines on anthrax surveillance and control and the formulation of templates to assist countries in the construction of their surveillance and control programmes. The latter was made possible by the active participation of the Department of Animal Production and Health, Ministry of Agriculture, Food and Fisheries, Zambia and the Livestock Development Programme, Mongu, Western Province, Zambia in a model country programme designed by the Working Group for the purpose. This paper elaborates on these achievements, particularly the lessons learned from the experience of Western Province, Zambia.

Protective efficacy of a recombinant protective antigen against Bacillus anthracis challenge and assessment of immunological markers

The efficacy of recombinant Bacillus anthracis Protective Antigen (rPA) produced in Bacillus subtilis and formulated in Alhydrogel or MPL-TDM-CWS (Ribi adjuvant) has been tested and compared to the licensed UK human vaccine in guinea pigs challenged by the aerosol route with the Ames strain of B. anthracis. rPA combined with the Ribi adjuvant was found to be the only formulation to provide 100% protection from challenge. Analysis of immunological parameters in the individual animals revealed significant differences between the rPA/Ribi vaccine group and rPA/Alhydrogel and human vaccine groups for antigen specific lymphocyte proliferation, PA neutralisation and antigen specific IgG2 levels, but indicated no significant differences in PA-specific IgG1 levels. rPA formulated in Alhydrogel induced a mainly IgG1 response whilst the rPA/Ribi vaccine produced a predominantly IgG2 response.

Airborne movement of anthrax spores from carcass sites in the Etosha National Park, Namibia

Tests for airborne movement of anthrax spores downwind from three heavily contaminated carcass sites were carried out under a range of wind conditions. Anthrax spores were detected in just three of 43 cyclone or gelatin filter air samples taken at distances of 6, 12 and 18 m from the sites. In addition, nine positives resulted during sampling sessions in which the site was mechanically disturbed, with a further five positives being found in sessions subsequent to those in which the site had been disturbed. The three positive samples not related to man-made disturbance were associated with the highest winds experienced during the study. Despite colony counts exceeding 100 on the culture plates in three instances, calculations showed that these represented very low worst case probable spore inhalation rates for animals or humans exposed to such levels. The low number of positives, the clear pattern of rapidly declining numbers of anthrax spores with distance downwind from the centres of the sites apparent on settle plates, and the persisting levels of contamination despite wind and rain, collectively suggest that the anthrax spores were associated with fairly heavy particles, although this was not seen by electron microscopy on soil samples from the sites. Overall, the findings are interpreted as indicating that it is very unlikely that Etosha animals contract anthrax by the inhalation route while simply in transit near or across a carcass site. The significance of the observations in relation to weather conditions in the Etosha, other studies on particulate aerosols in the region, and reports of long-distance airborne movement of microbes, is discussed.

Experimentally assessed public health risks associated with pigs from farms experiencing anthrax

Following an outbreak of anthrax in an intensive pig rearing unit in north Wales in 1989 a study was initiated by the Ministry of Agriculture, Fisheries and Food to assess public health risks during such an outbreak. Of 50 pigs infected by the addition of Bacillus anthracis spores to their feed, two died of anthrax six and eight days later. The remainder were observed for 21 days and exhibited only mild and transient clinical signs of disease. As judged by the results of bacteriological culture of appropriate tissues from the survivors, it was concluded that meat from healthy pigs killed 21 days after the latest case during an outbreak would not pose a public health risk.

Differentiation of Bacillus anthracis and other 'Bacillus cereus group' bacteria using IS231-derived sequences

Sequences based on the conserved 20 bp inverted repeat of IS231 variants were used as polymerase chain reaction-based fingerprinting primers of the member species of the Bacillus cereus group (B. anthracis, B. cereus, B. thuringiensis and B. mycoides), because of their close association with transposons, principally Tn4430 in B. thuringiensis. Fingerprints of B. anthracis were simple, and specifically allowed its identification and sub-differentiation from other members of the group. Fingerprints for B. cereus were strain-specific; those for B. thuringensis gave a 1650 bp product, characteristic of IS231 variants A-F. The same reaction conditions gave one or two bands for both B. anthracis and B. cereus that differed by restriction endonuclease mapping from the B. thuringiensis PCR product and established IS231 restriction maps; this does not preclude some kind of relationship between these products and IS231.

Evaluation of the Biolog system for the identification of Bacillus anthracis

The potential of the Biolog system for the identification of Bacillus anthracis was evaluated. In-house generated databases allowed the correct identification of 19 of 20 isolates of B. anthracis within 24 h. Five strains of the closely related B. cereus/thuringiensis group were misidentified as B. anthracis. For this reason the test could only serve as a primary screen with further testing being required to confirm identity. In addition 20% of all the strains of bacilli examined during the study gave unreadable reaction profiles due to false-positive reactions.

Ecology and epidemiology of anthrax in the Etosha National Park, Namibia

Analysis of mortality records has revealed distinct patterns in the incidence of anthrax in elephant and plains ungulates. The seasonal peak among the former is in November at the end of the dry season, while among the latter it occurs in March towards the end of the rainy season. Among elephants, there has been a notable spread of the disease to the west of the Park. Age and sex analyses indicate that, except for zebra, proportionally greater numbers of adult males die of anthrax among the species predominantly affected; however, zebra carcases are difficult to sex. In a study to identify possible environmental sources of infection, B. anthracis was detected in 3.3% of 92 water and 3.0% of 230 soil samples collected at different times of the year from 23 sites not associated with known cases of anthrax. Slight seasonal differences were noted with 5.7% positives occurring in the cold-dry period (May to August), 3.5% in the hot-dry season (September to December) and 1.4% in the hot-wet season (January to April). Higher rates (26.0% of 73 samples) were found in water from waterholes in the western part of the Park at the time of an outbreak in elephants. The possible importance of scavenger faeces was confirmed with > 50% of vulture, jackal and hyaena faeces collected from the vicinity of confirmed anthrax carcases yielding B. anthracis, sometimes in substantial numbers, while no spores were found in faeces not associated with known anthrax carcases. Despite terminal B. anthracis levels of usually > 10(7) cfu/milliliters in the blood of animals dying of anthrax, spore levels in soil contaminated by such blood at sites of anthrax carcases ranged from undetectable to a few tens of thousands. The rapid loss of viability in soil and water of anthrax bacilli was monitored experimentally and the importance of soil type demonstrated. Survival and extent of sporulation of the bacilli in water were shown to be dependent on the rate at which the blood was diluted out. Other relevant parameters examined were background flora, pH and sunlight.

Differentiation of Bacillus anthracis from other Bacillus cereus group bacteria with the PCR

Variation among isolates of Bacillus anthracis was examined by using restriction fragmentation patterns and the PCR performed with arbitrary and sequence-specific oligonucleotide primers. The patterns were compared with the patterns generated from strains of closely related species belonging to the "Bacillus cereus group" of bacteria, including B. cereus, Bacillus thuringiensis, and Bacillus mycoides. All B. anthracis profiles were identical for each of 18 restriction enzymes, each of 10 arbitrary PCR primers, and a repetitive extragenic palindrome-specific PCR primer. The PCR profiles generated with a coliphage M13-based primer exhibited slight pattern variation in a 400- to 500-bp band region. The B. anthracis profiles were unique compared with the profiles of the other species examined. In these other species, strain-to-strain variations were observed. Our results showed that isolates of B. anthracis are almost completely homogeneous, indicating a clonal lineage, and are distinct from other members of the B. cereus group and that B. anthracis, as a species in its own right, may have evolved only relatively recently.

The development and assessment of DNA and oligonucleotide probes for the specific detection of Bacillus anthracis

Two DNA probes and a number of oligonucleotide probes were designed from the virulence factor genes of Bacillus anthracis. These probes were tested for specificity against 52 B. anthracis strains and 233 Bacillus strains encompassing 23 other species. A rapid slot blotting technique was used for screening the large numbers of isolates involved. All probes tested appeared to be specific for B. anthracis under high stringency conditions. These probes could differentiate between virulent and avirulent strains. The probes were also applied to the detection of B. anthracis in routine environmental and clinical samples. A non-radioactive hybridization and detection system based on digoxigenin-11-dUTP was developed.

Isolation and purification of Aeromonas sobria cytotonic enterotoxin and beta-haemolysin

Aeromonas sp., grown in tryptone soya broth supplemented with yeast extract, 0.6%, pH 7.5, and incubated with agitation at 100 oscillations/min for 15 h at 37 degrees C produced optimal amounts of beta-haemolysin and cytotonic enterotoxin. More prolonged incubation resulted in the loss of enterotoxic activity and anion exchange chromatographic analysis indicated the presence of a moiety capable of breaking down the toxin. Anion exchange fast protein liquid chromatography resulted in a single peak of haemolytic activity and two peaks with enterotoxic activity. The cytotonic enterotoxin was purified from the fraction most active in the infant mouse assay; the second peak, which did not cross-react immunologically, may represent a second cytotonic enterotoxin. Neither peak was observed in the chromatographic fractions of filtrates from strains devoid of activity in the infant mouse assay. Purified enterotoxin, estimated to have a mol. wt of 15 kDa by SDS-PAGE, caused fluid accumulation in the infant mouse assay, was non-haemolytic to rabbit erythrocytes, caused an increase in cAMP activity in tissue culture cells and did not cross-react immunologically with components of cholera toxin or the whole toxin. Purified beta-haemolysin had an estimated mol. wt of 55 kDa, lysed rabbit erythrocytes and did not cause fluid accumulation in the infant mouse test.

Serology and anthrax in humans, livestock and Etosha National Park wildlife

Results are presented from a number of epidemiological studies using enzyme immunoassays (EIA) based on the purified anthrax toxin antigens, protective antigen, lethal factor and oedema factor. Studies on sera from a group of 62 human anthrax patients in Turkey and from cattle in Britain following two unrelated outbreaks of anthrax show that EIA using protective antigen can be a useful diagnostic aid and will detect subclinical infections in appropriate circumstances. A serological survey on wildlife in the Etosha National Park, Namibia, where anthrax is endemic, showed that naturally acquired anthrax-specific antibodies are rare in herbivores but common in carnivores; in carnivores, titres appear to reflect the prevalence of anthrax in their ranges. Problems, as yet unresolved, were encountered in studies on sera from pigs following an outbreak of anthrax on a farm in Wales. Clinical details, including treatment, of the human and one of the bovine outbreaks are summarized and discussed in relation to the serological findings.

Bacillus anthracis but not always anthrax

Gram-positive bacilli isolated during epidemiological investigations which, on the basis of conventional tests, resemble Bacillus anthracis but which fail to produce the capsule or to induce anthrax in test animals have long been dismissed in clinical and veterinary laboratories as B. cereus or simply as unidentified Bacillus spp. and thereupon discarded as inconsequential. In this study, the application of newly available DNA probe, polymerase chain reaction and specific toxin antigen detection technology has revealed that a proportion of such strains are B. anthracis which lack the plasmid carrying the capsule gene (pXO2). While these techniques cannot, of course, be used to confirm the identities of strains resembling B. anthracis but which also lack the plasmid carrying the toxin genes (pXO1), the likelihood that these also are bona fide B. anthracis becomes more acceptable. (As yet no naturally occurring pXO1-/2+ strains have been found.) At this point, the significance of the presence of such avirulent forms of B. anthracis in specimens can only be a subject for speculation, but the possibility that they may be indicators of virulent parents somewhere in the system being examined must be considered.

Anthrax vaccines: past, present and future

Most livestock vaccines in use throughout the world today for immunization against anthrax are derivatives of the live spore vaccine formulated by Sterne in 1937 and still use descendants of his strain 34F2. Credit belongs to this formulation for effective control in many countries with considerable reduction, sometimes complete elimination, of the disease in animals and, since man generally acquires it from livestock, in man also. However, there are some contraindications of its use and situations in which it cannot be easily administered, and room for development of a successor is discussed. The human vaccines, formulated for at-risk occupations and situations, date from the 1950s (UK vaccine) and 1960s (US vaccine). The rather greater need for improvement of these as compared with the veterinary vaccine stimulated valuable research during the 1980s which has led to a number of promising candidate alternatives for the future.

Anthrax in wildlife in the Luangwa Valley, Zambia

An abnormally high mortality among hippos (Hippopotamus amphibius) in the Luangwa River valley between June and November 1987 and estimated to number more than 4000 deaths was attributed to anthrax. Several other species, particularly Cape buffalo (Syncerus caffer) and elephant (Loxodonta africana), appear to have been affected. A smaller outbreak of anthrax in hippos occurred between August and September 1988, approximately 100 km up-river. A field study was arranged in August 1989 to assess the extent of environmental contamination by Bacillus anthracis and the risks to people in the area, to study possible methods of control and to equip local laboratory staff for continued monitoring of the disease. The study confirmed the enzootic status of the region. The characteristics of the outbreaks of anthrax in 1987 and 1988, and the results of the field study are described.

Antibodies to anthrax toxin in humans and guinea pigs and their relevance to protective immunity

A forerunning study on the relationship between antibodies to the protective antigen (PA) and lethal factor (LF) components of anthrax toxin and protective immunity has been expanded and extended to include the third toxin component, the edema factor (EF). It was found that protection against the "vaccine resistant" Ames strain was possible in the absence of detectable anti-LF and anti-EF antibodies. Evidence is given that PA may be the essential anthrax-derived antigen for protection, but that equally essential is that it be presented to the host's immune system in such a manner as to provide stimulation of more than just production of antibody to PA. Titers to the three components in sera of individuals with histories of clinically diagnosed anthrax as well as from human vaccinees are included in the report.

Purification of anthrax-toxin components by high-performance anion-exchange, gel-filtration and hydrophobic-interaction chromatography

A procedure has been developed for purification of the tripartite anthrax-toxin components. This involves sequential high-performance anion-exchange, gel-filtration and hydrophobic-interaction chromatography. From an initial culture volume of 15 litres, typical yields of 8 mg of protective antigen, 13 mg of lethal factor and 7 mg of oedema factor are produced to higher degrees of purity than have previously been achieved by conventional chromatographic techniques.

Development of antibodies to protective antigen and lethal factor components of anthrax toxin in humans and guinea pigs and their relevance to protective immunity

A competitive inhibition enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies in serum to the protective antigen (PA) and lethal factor (LF) components of anthrax toxin. Current human vaccination schedules with an acellular vaccine induce predictable and lasting antibody titers to PA and, when present in the vaccine, to LF. Live spore vaccine administered to guinea pigs in a single dose conferred significantly better protection than the human vaccines (P less than 0.001), although they elicited significantly lower (P less than 0.0005) anti-PA and anti-LF titers at time of challenge with virulent Bacillus anthracis. Substantial anti-PA and anti-LF titers may not, therefore, indicate solid protective immunity against anthrax infection. The ELISA system was also shown to be capable of detecting anti-PA and anti-LF antibodies in the sera of individuals with histories of clinical anthrax. The advantage of ELISA over the Ouchterlony gel diffusion test and indirect microhemagglutination assay are demonstrated. There was a highly significant degree of correlation between ELISA and the indirect microhemagglutination assay (P less than 0.0005); but ELISA was markedly superior in terms of reproducibility, reliability, specificity, and simplicity in performance and stability of the bound antigen.

Intestinal carriage of Bacillus cereus: faecal isolation studies in three population groups

The results of examinations of stools for Bacillus cereus among three unrelated groups of individuals are presented. The groups consisted of (1) healthy school-children aged 6-11 years in a rural region of South Africa examined during each of the four seasons of the year; (2) 15 healthy volunteers comprising staff of a London microbiology laboratory and their families examined on each of 3 consecutive weeks; (3) 75 unrelated young children, 2 months to 5 years of age, in a second rural region of South Africa examined during a pilot study of 1 week's duration on the aetiology of rural gastroenteritis. The stools of the last group were submitted as being related to present or recent diarrhoea in the respective children. In group 1, B. cereus isolation rates ranged from 24.3% at the autumn visit to 43% at the summer visit with a significantly higher rate of isolation in the summer than at other seasons of the year (P less than 0.05). B. cereus was isolated from 40% of group 2 volunteers on week 1, none on week 2 and 20% on week 3. The organism was detected in the 12 positive specimens at levels of approximately 10(2)/g and constituted 2.5-30% of the total aerobic spore-forming bacillus population in the stools. In group 3, B. cereus was recovered from 18.7% of the stool samples and was isolated consecutively with other pathogens (enteropathogenic Escherichia coli and rotavirus) on only five occasions. In groups 1 and 3, less than 5% of the stools had '3+' levels of B. cereus (greater than 10 colonies per direct plate culture). B. cereus was readily isolated from all of 10 food samples, representative of the typical diet of the group 1 individuals, and was present in substantial numbers (10(4) to 5.5 X 10(6)/g) in half of them. The isolation results, supported by serotyping, indicated that carriage of B. cereus in stools is transient and its presence at any one time reflects solely its intake with foods.

In vitro and in vivo cholera toxin production by classical and El Tor isolates of Vibrio cholerae

A comparative study was carried out on the in vitro production of cholera toxin by 19 Vibrio cholerae El Tor isolates from patients with cholera in South Africa, one El Tor isolate from a patient in Malawi (a country approximately 1000 km north-northeast of South Africa), 6 El Tor and 12 classical type isolates from patients in Bangladesh, and 5 culture collection classical strains. Identical phage types and indistinguishable toxigenicities among the South African and Malawi V. cholerae, representing isolations obtained over a 10-year period, indicated that essentially a single strain was involved in the cholera of these regions. Similarly, phage typing and toxin profiles indicated that the 12 classical and 6 El Tor V. cholerae cultures in Bangladesh, all isolated in November 1983, represented just two strains. As assessed by titrations in Y-1 mouse adrenal and Chinese hamster ovary cell lines, the general order of toxigenicities was Bangladesh and culture collection classical greater than Bangladesh El Tor greater than southern African El Tor. The African isolates consistently gave rise to very low titers. Their relative reluctance to produce the toxin in vitro compared with the culture collection classical strains, particularly strain 569B, was confirmed by rocket electrophoresis. In somewhat of a contrast, maximum in vivo titers in rice water stools from cholera patients in South Africa and from both classical and El Tor type cholera patients in Bangladesh were essentially equal. It is postulated that under the continuous culture conditions that occur in vivo, cholera toxin concentrations can accumulate to a maximum level, depending on the rate of purging by the diarrheal fluid rather than the toxigenicity of the infecting stain. The relevance of these findings to the relative severities of classical and El Tor types of cholera is discussed.

Passage of Salmonella enteritidis and Salmonella thompson through chick ileocecal mucosa

The passage of Salmonella enteritidis and S. thompson across the cecal mucosa has been visualized in an electron microscope study with the freshly hatched chick as a model. The uptake of salmonellae by macrophages took place in the cecal lumen; the macrophages became abnormal and often ruptured to release organisms back into the lumen. The entry of bacteria into the epithelial cells was associated with a series of pathological changes, beginning with the appearance of active Golgi apparatus and the production of a variety of lysosomal vesicles. Salmonellae became sequestered within lysosomes but were unaffected by the presence of hydrolytic enzyme. Epithelial cell death was related to particularly large numbers of bacteria. Fragments of invaded epithelial cells, especially those undergoing cell death, contributed to the cytoplasmic debris and released further salmonellae into the lumen. Bacteria were never observed in large numbers below the basement membrane, and there was no significant pathology in the lamina propria tissue. Wandering cells, identified as macrophages and containing the bacteria, were observed spanning the epithelial and lamina propria regions through breaks in the basement membrane. It is suggested that the passage of bacteria from the epithelium to the lamina propria is primarily the result of capture and transport within host macrophages.

Enterotoxin production in relation to taxonomic grouping and source of isolation of Aeromonas species

A total of 19 of 20 (95%) strains of Aeromonas hydrophila biovar hydrophila and 16 of 17 (94%) strains of Aeromonas sobria isolated from a variety of clinical and environmental sources were found to be enterotoxin positive. Only 2 of 18 (11%) A. hydrophila biovar anaerogenes and 2 of 13 (15%) unidentified Aeromonas strains from a similar variety of sources produced enterotoxin. No association was apparent between the source of isolation, in particular diarrheal stools, and enterotoxigenicity; 41% of the isolates from diarrheal stools were enterotoxin negative. A strong correlation was noted between ability to produce enterotoxin and positive results in six characters: lysine decarboxylase and Voges-Proskauer reactions, production of gas from glucose, gluconate oxidation, xanthine hydrolysis, and hemolysis of human erythrocytes. In the majority of cases (35 of 39 strains), enterotoxigenicity was detected using cell-free filtrates of brain heart infusion broth cultures grown at 36 degrees C for 15; however, the other four positive isolates were detected after growth in the same broth at 30 degrees C or in Casamino Acids-yeast extract broth at 30 or 37 degrees C. It is recommended that for enterotoxin tests, strains should be grown in both media at both temperatures. The infant mouse test was found to be a simple and reliable method for detection of the enterotoxin. The toxin proved to be heat labile and not neutralized by cholera antitoxin.

Non-gastrointestinal Bacillus cereus infections: an analysis of exotoxin production by strains isolated over a two-year period

Isolates of Bacillus cereus from 118 cases, and two maternity unit outbreaks, of non-gastrointestinal infection were grouped on the basis of their estimated probable involvement in the infections from which they were isolated: (i) high probability--48 strains; (ii) intermediate--16 strains; (iii) low--7 strains; (iv) very low ("irrelevant")--49 strains. Rabbit skin test, haemolysin and phospholipase assays were used to determine exotoxin activities of strains within each group. The results suggest a significant relation between the virulence of an isolate as reflected in the degree to which it appeared responsible for the signs and symptoms of an infection, and its toxigenicity in the skin test. This is attributed to the ability of B cereus strains to synthesise, in varying degrees, a necrotic enterotoxin, possibly in conjunction with the primary haemolysin (cereolysin). The cases analysed in this study support the contention that B cereus, when isolated from an infection, may not be an inconsequential contaminant and should not be too readily dismissed as such.

The problem of bacillus species infection with special emphasis on the virulence of Bacillus cereus

Although Bacillus cereus is an uncommon ocular pathogen, infection with it usually results in loss of the eye. Although previous reports have emphasized endogenous infection, our recent experience indicates the importance of B cereus infection following trauma. Management is hampered by ineffectiveness of current empirical antibiotic regimens. This microorganism is resistant to both the penicillins and the cephalosporins. Although B cereus is susceptible to gentamicin, our studies indicate that gentamicin by itself is inadequate to eradicate the infection. B cereus, however, is susceptible to clindamycin and combined therapy with gentamicin and clindamycin appears to offer the best approach. Early diagnosis is the key to successful treatment. We believe the clinical circumstances likely to lead to B cereus infection, as well as the manifestations of the disease itself, are sufficiently distinctive to alert the ophthalmologist to the possibility of this infection. Prompt recognition of the infection should allow institution of appropriate therapy before permanent structural changes occur.

Computer-assisted method for identification of Bacillus species isolated from liquid antacids

One hundred nineteen species of Bacillus were isolated from five heavily contaminated liquid antacids and their constituent chemicals. The 66 different reaction profiles obtained were expressed in probability figures and stored in a computer. A total of 13 Bacillus species were identified, with B. coagulans, B. licheniformis, B. subtilis, and B. polymyxa present at particularly high frequencies. The potential advantage of using a computer in the identification of aerobic sporeformers is demonstrated.

Application of serological typing to the investigation of outbreaks of Clostridium perfringens food poisoning, 1970-1978

Serological typing was used as an epidemiological tool in the investigation of 524 outbreaks of Clostridium perfringens food poisoning in the United Kingdom and 37 outbreaks in other countries. Five thousand five hundred and fifty-four (77%) of 7245 strains of C. perfringens associated with the 561 outbreaks were typable with the 75 Food Hygiene Laboratory antisera; in 354 (63%) of these outbreaks a specific serotype was established as being responsible for the outbreak. An assessment is made of the ability of two additional sets of antisera, prepared against 34 American and 34 Japanese strains of C. perfringens, to increase the number of strains which can be typed. The extent of cross-reaction between the three sets of antisera was determined and the results are discussed in relation to the source and history of the type strains.

Two gas-gangrene-like infections due to Bacillus cereus

Two cases of postoperative gas-gangrene-like infection due to Bacillus cereus are reported, drawing attention to the fact that Bacillus cereus, a common environmental bacterium, can occasionally give rise to severe post-operative infection. Characteristics of the organism related to the epidemiology and pathogenesis of such infections are discussed.

Severe clinical conditions associated with Bacillus cereus and the apparent involvement of exotoxins

Twenty-one cases of infection with Bacillus cereus are summarised. The histories supplied showed that at least 15 of these were associated with severe or potentially severe symptoms including two deaths. Analysis of the production of exotoxins, including haemolysin and phospholipase, by these strains is given, and the relevance of these metabolites to the severity of the condition is discussed. Three incidents of bovine mastitis resulting from B. cereus and involving three deaths are also included. The observations presented here together with those of previous reports which are reviewed indicate that B. cereus may be of clinical importance, not just an opportunist but also as an agent of potentially severe infections in its own right.

Properties and production characteristics of vomiting, diarrheal, and necrotizing toxins of Bacillus cereus

Evidence is provided that the enterotoxin of Bacillus cereus variously described in the literature as diarrheagenic toxin, diarrheal agent, fluid accumulation factor, vascular permeability factor, dermonecrotic toxin, and intestinonecrotic toxin is a single relatively unstable protein of molecular weight approximately 50,000 and isoelectric point of the order of 4.9. It is presumed to be the enterotoxin responsible for the diarrheal-type B. cereus food poisoning syndrome and it may also be the pyogenic and pyrogenic factor in nongastrointestinal B. cereus infections of man and animals. The enterotoxin is a vegetative growth metabolite produced to one degree or another by almost all B. cereus strains and is readily separated from phospholipase and heat-labile cereolysin but less readily differentiated from a heat-stable hemolysin. It is lethal to mice but may also be separable from another mouse lethal factor by electrofocusing. The emetic toxin responsible for the vomiting-type B. cereus food poisoning syndrome is clearly distinguishable from the diarrheal and other toxic factors and appears to be a highly stable compound of molecular size less than 5000.

A model of salmonella enteritis: the behaviour of Salmonella enteritidis in chick intestine studies by light and electron microscopy

Salmonella enteritidis was injected into isolated "loops" of duodenum, midgut and ileocaeca in anaesthetized 1-day-old chicks. Using light microscopy with conventional staining and fluorescent antibody techniques, the organism were observed in increasing numbers in the epithelium and lamina propria of each region between 2 and 12 h after inoculation. The potential ability of the salmonellas to enter the mucosa at any level of the intestine was thus demonstrated. The penetration of caecal epithelium by the organisms was studied by electron-microscopy. Uptake of salmonellas was associated with evaginations which formed at the luminal surface of the epithelium. In the epithelial cells, the bacteria were enclosed within membrane-bound vacuoles and appeared undamaged by intracellular passage. Surface evaginations almost completely replaced the brush border in regions where large numbers of the organisms were involved. Occasional salmonellas were found in the lamina propria both free and intracellularly. Results of culture and light microscopy following oral and intracloacal inoculation are also presented.

A severe necrotic enterotoxin produced by certain food, food poisoning and other clinical isolates of Bacillus cereus

The ability of certain strains of Bacillus cereus consistently to elaborate a filterable non-dialysable toxin capable of causing severe disruption and necrosis of the intestinal mucosa and submucosa is confirmed. This property is not universal to all B. cereus strains and different degrees of production of this toxin are exhibited by the different strains which produce it. The necrotic effect is produced by whole-cell cultures of the toxin producing strains in broth and in boiled rice. Some characteristics of this necrotic toxin are described and its relationship with the diarrhoeal and other known B. cereus toxins is discussed.

Escherichia coli O 27 in adult diarrhoea

Escherichia coli O 27 H 7 was found in 16 stool samples submitted during a Caribbean cruise (Cruise Z) by 29 patients reporting with diarrhoea. A retrospective search revealed E. coli O 27 H 7 in 11 of 20 and 2 of 14 stool cultures from patients on two previous cruises (Y and X respectively) and in a culture from fresh cream (Cruise Y). The repeated occurrence of E. coli O 27 H 7 in the absence of any other apparent cause suggested that this serotype may have been responsible for the diarrhoea. The results of pathogenicity tests suggested that this strain elaborated heat-stable (ST) enterotoxin. The possibility that food may have been the vector is discussed.

A serotyping system for Clostridium welchii (C. perfringens) type A, and studies on the type-specific antigens

A serotyping scheme for Clostridium welchii (C. perfringens) type A employing 57 antisera has been used to investigate the epidemiology of 153 food-poisoning outbreaks and 32 cases of gas gangrene and other clinical infections. Respectively 65% and 59% of the isolates were typable, and in 55% of the food-poisoning outbreaks the causative serotypes were established. Isolation and reporting methods that would render the typing scheme of even greater epidemiological value are described. The type-specific antigen was shown to reside in the capsule and to be lost from strains that had become rough. Development of roughness and its prevention are described. A great range of antisera and an internationally acceptable serotyping scheme is expected after integration of this set with those developed independently in America and Japan.

Studies on the production of enterotoxins by Bacillus cereus

Evidence is presented for the existence of three distinct enterotoxins detected in concentrated cell-free culture filtrates of selected Bacillus cereus strains. The first was a product capable of stimulating the adenylate cyclase-cyclic-AMP system in intestinal epithelial cells and, possibly through this, causing fluid accumulation in ligated ileal sections ("loops") of young rabbits. This was elaborated by a strain isolated from an incident of diarrhoea and which caused diarrhoea in 6 of 10 monkey feedings. The second was tentatively identified as a factor which caused fluid accumulation in rabbit loops but not, apparently, through stimulation of the adenylate cyclase-cyclic-AMP system; this was elaborated by a strain isolated from raw rice which failed to produce symptoms in eight monkey feedings. Together, the behaviour of these two factors indicates that diarrhoea caused by B. cereus enterotoxin may be a cyclic-AMP-mediated event. The third, here referred to as "pyogenic toxin", caused severe tissue damage in the ileal mucosa and was elaborated by a strain isolated from a brain abscess. A factor produced by a strain isolated from an outbreak of vomiting which caused vomiting in 10 of 24 monkey feedings could bot be detected in tests reported here but appears to be a fourth enterotoxin type. Cytopathic effects in tissue cultures, suckling mouse tests, and assays of glycerol production by fat cells were not found to be of value in the detection of any of the enterotoxins.

Identification of a novel enterotoxigenic activity associated with Bacillus cereus

A strain of Bacillus cereus isolated from a food poisoning outbreak characterized by vomiting has been shown to be capable of causing vomiting when cultures grown on rice, but not other media, were fed to Rhesus monkeys. In contrast, a strain isolated from a diarrhoeal outbreak produced diarrhoea, but not vomiting, when grown on various media in similar feeding trials. Furthermore, culture filtrates from the diarrhoeal strain caused fluid accumulation in ligated rabbit ileal loops whereas those from the vomiting strain did not. It is proposed that at least two enterotoxins are involved, one responsible for the vomiting and one for the diarrhoeal symptoms.