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Biomedical subjects

V Burke

Publications and source records attributed to V Burke.

At least 127 records · Page 7Linked to original sources
PubMed1987

Purification of cytotoxic enterotoxin of Aeromonas sobria by use of monoclonal antibodies.

Cytotoxic enterotoxin of Aeromonas sobria was purified by affinity chromatography with monoclonal antibodies. The purified enterotoxin gave a single protein band in polyacrylamide gradient gel electrophoresis and its mol. wt estimated by this technique was 63,000; it had a pI of 6.2. The purified enterotoxin caused fluid accumulation in rat ileal loops and in infant mice, was cytotoxic to cultured cells, was haemolytic to human erythrocytes, and was lethal to mice after intravenous injection. The relative concentrations of enterotoxic, cytotoxic and haemolytic activities were approximately the same in a culture filtrate and in purified, electrophoretically homogeneous enterotoxin. The three activities were also inactivated to the same extent after incubation for 10 min at 56 degrees C. There was no immunological cross-reactivity with cholera toxin (CT) nor did antiserum to CT neutralise the biological effects of the toxin.

Aeromonas↗
PubMed1987

Aeromonas cytotonic enterotoxin cross reactive with cholera toxin.

Isolation by affinity chromatography from crude culture filtrate of Aeromonas sobria of protein that cross reacted with cholera toxin (CT) revealed a toxin that produced fluid accumulation in rat ileal loops and in infant mice and caused rounding of Y1 adrenal cells. All these activities were neutralised by antiserum to CT. There was no haemolytic or cytotoxic activity associated with this CT-cross reactive cytotonic enterotoxin. CT-cross reactive material detected in enzyme linked immunosorbent assay (ELISA) was produced by 25% of Aeromonas isolates from faeces of children with or without diarrhoea-26% of A. sobria, 20.0% of A. hydrophila and 24% of A. caviae tested gave positive ELISA results. Most strains that produced this cytotonic enterotoxin but no cytotoxic enterotoxin were isolated from children without diarrhoea. Toxin preparations from Aeromonas spp. that completely inhibited adenosine-5'-diphosphate-induced platelet aggregation, an effect related to elevation of intracellular cAMP, were, with one exception, cross reactive with CT in ELISA.

Aeromonas↗
PubMed1987

Pyloric stenosis in Western Australia, 1971-84.

Analyses of hospital records and census data for 1971-84 showed no significant increase in incidence of infantile hypertrophic pyloric stenosis in Western Australia. No link was found between breast feeding and incidence of disease. Low birth weight, short gestation pregnancies, and paternal family history of the disease were significant features.

Australia↗
PubMed1987

Biotyping as a method of screening for enterotoxigenic Escherichia coli.

A scheme of biotyping described originally for E. coli isolated from urine was used to investigate enterotoxigenic (ETEC) and non-enterotoxigenic (non-ETEC) fecal E. coli. Primary biotype was determined by fermentation of raffinose, sorbose and dulcitol and decarboxylation of ornithine. Failure to ferment sorbose correlated best with enterotoxicity; 95.5% of ETEC and less than 40% of non-ETEC did not ferment sorbose. The sensitivity compares favourably with reported results of the use of polyvalent antisera for recognition of serotypes associated with ETEC, although specificity was lower using biotyping. Strains included in our study were mainly from Australia, New Zealand or Indonesia and we do not know if our observations apply to E. coli isolated elsewhere. If failure to ferment sorbose proved to be a characteristic of most ETEC, this reaction offers the possibility of developing selective media to increase the yield of ETEC from primary plates for laboratories in which gene probe techniques for recognition of ETEC are not available.

Bacteriological Techniques↗
PubMed1986

Haemagglutination patterns of Aeromonas spp. related to species and source of strains.

The study included 138 A. sobria and 182 A. hydrophila isolated in Perth from samples of diarrhoeal or non-diarrhoeal faeces or from domestic water. Strains were grouped in relation to agglutination of human, horse, rat and guinea pig erythrocytes and the effect of sugars on haemagglutination. Agglutination of red cells of all four species (primary group 1) was most commonly associated with A. sobria, particularly those strains isolated from faeces of patients with diarrhoea. Most A. hydrophila associated with diarrhoea also belonged to group 1 but A. hydrophila from non-diarrhoeal stools or from water most commonly agglutinated human and guinea pig cells but not horse erythrocytes (primary groups 2 and 3). Fucose-resistant haemagglutination (FRHA) of strains in primary group 1 occurred with about 68% of the strains of A. sobria associated with diarrhoea. Mannose-resistant haemagglutination (MRHA) was limited to 29% of strains of A. sobria associated with diarrhoea. The predominance of primary group 1 among strains of Aeromonas spp. associated with diarrhoea and the proportion of these strains showing FRHA suggest that haemagglutination of cells from human, horse, rat and guinea pig, particularly if fucose-resistant, should be considered in a search for characteristics, which possibly contribute to virulence of Aeromonas spp.

Aeromonas↗
PubMed1986

Protection of rats against cholera toxin and cholera-like enterotoxins by immunization with enteric-coated cholera toxin.

Pure cholera toxin (CT) given as a booster in enteric-coated tablets to rats produced a humoral and intestinal immune response similar to the result of instilling the boosting dose of CT directly into the duodenum. This method protects the antigen against gastric acid and allows delivery of the immunogen to intestinal mucosa, an essential step in producing intestinal secretory IgA. Immunization gave protection against pure CT during intestinal perfusion but also significantly protected against the secretory effects of E. coli LT and CT-like toxin of A. sobria. The use of enteric-coated vaccines offers advantages for mass immunization programmes and our results suggest that immunization with preparations containing CT holotoxin may protect against heterologous toxins which cross-react with CT.

Aeromonas↗
PubMed1986

Partial characterisation of a soluble haemagglutinin from human diarrhoeal isolates of Aeromonas.

A soluble haemagglutinin has been identified in cell-free culture supernates of human diarrhoeal isolates of Aeromonas sobria, A. hydrophila and A. caviae. It was oligomeric; a major peak of haemagglutinating activity had an apparent mol. wt of 780,000 but there was haemagglutinating activity throughout the mol. wt range less than 40,000- greater than 10(6). Human group O, A and B, horse, rabbit, chicken and rat erythrocytes, but not those of sheep and cow, were agglutinated by the soluble haemagglutinin, in contrast to the cell-bound agglutinin. Agglutination was inhibited by fetuin, a complex glycoprotein, but not by simple sugars. The haemagglutinating activity was not affected by 0.5 M NaCl, dithiothreitol or the presence or absence of Ca++. It was unrelated to the haemolytic, enterotoxigenic and proteolytic activities present in cell-free extracts of A. sobria. All A. sobria, 73% of A. hydrophila and 68% of A. caviae strains tested produced this soluble haemagglutinin. A. caviae does not appear to be an enteric pathogen, therefore this soluble haemagglutinin alone is unlikely to be a virulence factor in Aeromonas spp.

Adult↗
PubMed1986

Comparison of direct plating with the use of enrichment culture for isolation of Aeromonas spp. from faeces.

Direct plating of faecal specimens on blood agar was compared with the use of enrichment culture for isolation of Aeromonas spp. from faeces during a large epidemiological study. Of enterotoxigenic strains isolated by direct plating, 89% were associated with acute diarrhoea and 7% with an episode of diarrhoea during the month before collection, but 79% of enterotoxigenic strains isolated only after enrichment were not associated with acute diarrhoea. With Aeromonas spp., as with intestinal pathogens, it appears that enrichment allows isolation of the bacteria when in low faecal concentrations likely to be found in convalescent patients, carriers and those with subclinical infection. The routine use of enrichment for isolation of faecal aeromonads, by detecting Aeromonas spp. in low numbers in patients without diarrhoea, is likely to confuse interpretation of epidemiological studies seeking to clarify the relationship between Aeromonas spp. and acute diarrhoea.

Aeromonas↗
PubMed1985

Use of non-carbonated soft drinks to provide safe drinking water.

Non-carbonated, low-calorie soft drink concentrates (cordials), when diluted according to manufacturers' instructions, had significant antibacterial effects in vitro. Bacteria affected include Vibrio cholerae, Aeromonas hydrophila, Shigella sonnei, Salmonella typhimurium and Escherichia coli. With vibrios, bacterial counts were reduced from 10(6)/ml to undetectable numbers in less than 10 min. Escherichia coli in an initial concentration of 10(6)/ml became undetectable after incubation for 1 h with one brand of cordial. Naturally contaminated water can be rendered potable by incubation with cordials at room temperature for 1 h. This may be a way to reduce the risk of water-borne diarrhoea, particularly where the cleanliness of drinking waters cannot be otherwise assured, for example when making up oral rehydration fluids and for travellers in high-risk areas.

Bacteria↗
PubMed1985

Breast milk lactoferrin levels in relation to maternal nutritional status.

Lactoferrin was measured in breast milk from Aboriginal and non-Aboriginal Australian women using an enzyme immunoassay. There was no diurnal variation in lactoferrin concentration or change in concentration between the beginning and end of a feed. Lactoferrin levels were significantly higher in the first 15 days postpartum than in the period after the 15th day. Regression analysis showed that in milk from Aboriginal women less than 15 days postpartum, higher concentrations of lactoferrin were associated with weight for height (WFH) greater than 90% and with increased parity. Comparable data were not available for Caucasian women. For Aboriginal and Caucasian women more than 15 days postpartum, lactoferrin concentrations were higher in women greater than 90% WFH. Other variables, such as parity, were not significant in the regression.

Adult↗
PubMed1985

Invasion of HEp-2 cells by fecal isolates of Aeromonas hydrophila.

Human diarrheal isolates of Aeromonas hydrophila were found to be invasive in HEp-2 cell monolayers. Microscopic examination of two isolates from patients with symptoms of dysentery revealed that infected HEp-2 cells contained up to 50 bacteria localized within areas of the cytoplasm. A quantitative invasion assay was developed, using viable counts of total intracellular bacteria. Five fecal isolates of A. hydrophila were classified as invasive, with an average of 0.1 up to 2 bacteria per HEp-2 cell, as compared to 7 for an invasive Escherichia coli strain. 3 other fecal isolates, 1 reference strain, and 10 water isolates of A. hydrophila were similar to a noninvasive E. coli strain, with less than 0.008 bacteria per HEp-2 cell. All isolates were screened for plasmid DNA; no common plasmid was found in the invasive strains, and the loss of a 6.0-megadalton plasmid from one of these strains had no observable effect on invasiveness. Thus some A. hydrophila isolates are capable of cellular penetration and replication, and this may be an important chromosomally determined virulence property of the organism.

Aeromonas↗
PubMed1985

Invasiveness of Aeromonas spp. in relation to biotype, virulence factors, and clinical features.

Of 69 fecal isolates of Aeromonas spp., 18 had the ability to invade HEp-2 cells. Invasiveness correlated with biotype; of the 18 invasive strains, 16 were A. sobria and 2 were A. hydrophila. No invasive strains were found among the A. caviae. Of the 18 invasive strains, 13 were enterotoxigenic. Of the enterotoxigenic and invasive strains, 12 were A. sobria, but enterotoxicity was also more common among noninvasive strains of A. sobria. Fucose-resistant hemagglutination was also more common in A. sobria, but invasive strains were equally divided between fucose-resistant hemagglutination and other patterns. Detailed clinical information was available for 27 of the 69 strains. All 15 strains of A. sobria or A. hydrophila associated with diarrhea were enterotoxigenic; 6 of the 10 strains of A. sobria were also invasive. Blood was present in the stool samples of five of the six patients with invasive A. sobria and in none of the patients with noninvasive strains. Although limited, these observations suggest that dysenteric symptoms may be produced by invasive Aeromonas spp.

Adult↗
PubMed1984

Aspirin in acute gastroenteritis: a clinical and microbiological study.

Soluble aspirin given by mouth in divided dosage decreased intestinal fluid loss in infants and young children with acute gastroenteritis. The treated group had significantly less diarrhea, which ceased earlier and needed less intravenous therapy, than a randomly selected control group given an indistinguishable placebo. This effect of aspirin occurred with diarrhea caused by Salmonella, Aeromonas, Escherichia coli producing heat-labile toxin, and rotavirus, but not with diarrhea associated with strains of E. coli producing heat-stable toxin.

Acute Disease↗
PubMed1984

Media for isolation of Aeromonas spp. from faeces.

Five solid media were evaluated for isolation of Aeromonas spp. from faeces: desoxycholate citrate agar (DCA), MacConkey's agar (MAC), xylose-desoxycholate-citrate agar (XDCA), Rogol's medium (ROG), which contained ampicillin 20 mg/L and p-nitrophenyl-glycerine 25 mg/L as inhibitors, and blood agar (BA) with ampicillin 10 mg/L. False negative oxidase tests limited the usefulness of DCA and MAC and, although the use of XDCA avoided the problem of fermentation of lactose, some Aeromonas spp. failed to grow on XDCA or produced minute colonies unsuitable for oxidase tests. BA yielded the highest rate of isolation for Aeromonas spp. from 323 faecal samples--15.2% for all Aeromonas spp. and 9.3% for enterotoxigenic (ENT+) strains. This compares with 10.8% for all strains and 6.5% for ENT+ strains isolated on DCA, 7.1% for all strains and 4% for ENT+ strains on MAC and 4% for all strains and 1.5% for ENT+ strains on ROG. Blood agar with ampicillin is recommended for isolation of Aeromonas spp. from faeces.

Aeromonas↗