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Biomedical subjects

M Gracey

Publications and source records attributed to M Gracey.

At least 127 records · Page 7Linked to original sources
PubMed1983

Correlation of enterotoxicity with biotype in Aeromonas spp.

Enterotoxin production correlated with biotype in a study of 686 strains of Aeromonas spp. from Indonesia, Thailand, the United States, and Western Australia. Most strains were isolated from feces but nonfecal human isolates and environmental strains were also included. More than 80% of Voges-Proskauer (VP)-positive strains, classified as A. hydrophila, were enterotoxigenic in the suckling mouse assay as were 90% of VP-positive, arabinose-negative strains. An association between positive VP, arabinose fermentation, and failure to produce enterotoxins was found only with environmental strains. VP-negative strains which did not oxidize gluconate or produce gas from glucose were classified as A. punctata subsp. caviae. Only 2 of the 286 strains produced enterotoxins, and both were from Indonesian fecal samples. There were few remaining VP-negative strains, classified as A. punctata subsp. punctata and, of these, about half were enterotoxigenic. Regardless of source and species, 97% of Aeromonas spp. were correctly classified in relation to enterotoxin production with a hemolysin assay. A combination of biochemical testing and hemolysin assay should be suitable for diagnostic laboratories to identify enterotoxigenic Aeromonas spp. which, in children, are associated with diarrhea, unlike non-enterotoxigenic strains.

Aeromonas↗
PubMed1982

Aeromonas-associated gastroenteritis.

Enterotoxigenic Aeromonas spp. were isolated from 118 (10.2%) children with diarrhoea and 7 (0.6%) of those without diarrhoea in a prospective, year-long study of 1156 children with gastroenteritis and the same number of age and sex matched controls. In Perth, Western Australia, aeromonas-associated diarrhoea is distinctly seasonal with a sharp summer peak. The disease most commonly presents in children under two years of age as watery diarrhoea of short duration and mild fever which require no specific treatment. In more than one-third of patients diarrhoea lasted for over 2 weeks and in almost one-quarter there was a dysentery-like illness. In some patients with aeromonas-associated diarrhoea the clinical features could be regarded as suggestive of ulcerative colitis.

Aeromonas↗
PubMed1982

Growth and feeding practices of Western Australian infants.

Records from 12 metropolitan and six country Child Health Centres in Western Australia confirm a recent trend back to breast feeding; more than half the mothers were still breast feeding at three months. This trend was most marked and sustained in the highest socioeconomic group. Weight gains in infancy showed negative correlation with duration of breast feeding. By 12 months of age, infants from families in the lowest socioeconomic group, who breast-fed least, were significantly heavier than those from the highest. This fits our data which show an association between social class and breast feeding, and breast feeding and weight gain.

Anthropometry↗
PubMed1982

Intestinal microflora and bacterial overgrowth in early life.

At birth the gut is sterile but later is continually exposed to potentially harmful agents: infective, toxic, and antigenic. The development of a strictly contained intestinal microflora reflects an important aspect of control over potentially noxious, environmental influences. Control of the intestinal microecology is dependent on many factors including intestinal peristalsis, the intraluminal environment, and microbial interactions. When these regulating mechanisms are lost, microbial contamination of the gut occurs and leads to the so-called "contaminated small-bowel syndrome." This has serious clinical consequences, including diarrhoea and malabsorption, and can occur in a wide range of clinical situations in infants and young children.

Adult↗
PubMed1982

Biochemical characteristics of enterotoxigenic Aeromonas spp.

Biotypes of Aeromonas spp. correlated well with enterotoxin production in a study of 174 strains. Using biochemical characteristics determined by conventional methods and multitest systems, we correctly classified 93% of the strains with regard to enterotoxin production. Most of the enterotoxigenic strains were Voges-Proskauer (VP) positive and did not hydrolyze arabinose, but VP-positive strains which hydrolyzed arabinose were mainly non-enterotoxigenic. Aeromonas punctata subsp. caviae, which is VP negative and does not oxidize gluconate or produce gas from glucose, was non-enterotoxigenic. Although the number of other VP-negative strains was small, most were enterotoxigenic. Discrimination was improved so that 97% of the strains were correctly classified if the hemolysin assay was used either for all strains or for only the VP-positive, arabinose-positive and VP-negative, non-A. punctata subsp. caviae strains. Because the proposed classification system does not require facilities for carrying out in vivo assays such as suckling mouse or ileal loop methods, the identification of enterotoxigenic Aeromonas strains should be possible in diagnostic laboratories and will facilitate epidemiological studies of the role of these organisms in acute diarrhea.

Aeromonas↗
PubMed1982

Immunological cross-reactivity of enterotoxins of Aeromonas hydrophila and cholera toxin.

Pre-incubation with anticholera toxin (ACT) significantly reduced intestinal secretion induced by cell-free broth preparations of heat-labile toxins (LT) of Escherichia coli and Aeromonas hydrophila in jejunal perfusion experiments in rats in vivo. Pre-incubation with ACT also prevented cytotoxicity by E. coli LT in the Y1 cell culture system. Pre-incubation had no effect on cytotoxicity in Y1 and L132 cell lines or on haemolytic activity with cell-free preparations of A. hydrophila. In another series of experiments rats were immunized with cholera toxin given as an intraperitoneal priming dose followed 12 days later by intraduodenal boosting. Immunization significantly protected against net intestinal fluid secretion induced by enterotoxigenic E. coli and A. hydrophila and by cholera toxin.

Aeromonas↗
PubMed1981

Breast feeding and growth of healthy infants.

Breast feeding was prevalent and sustained in a prospective growth study of healthy Perth infants and was accompanied by slower weight gains, compared to figures from the 1960s. This may have important effect on the future of young Australians.

Australia↗
PubMed1981

Diarrhoeal disease in Aboriginal and non-Aboriginal infants and young children in Western Australia.

There were remarkable differences in the rates of admission to hospital for gastroenteritis of Aboriginal and non-Aboriginal infants and children in Western Australia during the eight-year period, 1971 to 1978. Although Aborigines made up only 3.7% of the State's population under five years in 1976 (the last census year) they accounted for 42% of admissions to hospital for gastroenteritis and had 58% of the bed occupancy for that disease. The highest rates of admissions were for rural infants, whether they were Aboriginal or not. Other infections, particularly of the respiratory tract, were other common causes of admission to hospital. There has been a very encouraging decline in deaths from diarrhoeal diseases, particularly in young Aborigines, in the period reviewed. Hospital admission rates also decreased for Aborigines during the latter half of the study, with the largest fall occurring in metropolitan infants, but there is still a very wide gap between the rates experienced by the Aboriginal and non-Aboriginal population under five years of age.

Age Factors↗
PubMed1981

Exotoxins of Aeromonas hydrophila.

Eighty of 103 strains of Aeromonas hydrophila cultured at 100 rev./min produced heat-labile enterotoxins detected using the suckling mouse assay. Results in intestinal perfusion agreed with the suckling mouse test in all strains tested by both methods. Enterotoxic activity correlated with haemolysin and cytotoxin production, but 4% of strains would have been wrongly classified using haemolysin assay in place of the suckling mouse test and 11% misclassified on the basis of cytotoxin assay. There was a significant association between haemolytic and cytotoxic activity, but 15% of strains produced only one of these toxins. Haemolysin, cytotoxin and enterotoxin were not always associated in a given isolate. The time of appearance of exotoxins during bacterial growth and the effects of dialysis, heating and proteolytic enzymes also suggest that haemolysins, cytotoxins and enterotoxins of Aeromonas hydrophila are separate toxins and not different manifestations of the same toxin.

Aeromonas↗
PubMed1981

Impaired gastric function in experimental malnutrition.

Selective dietary protein deprivation led to impaired pentagastrin stimulated gastric acid secretion in rats but was not simply due to lower body weights in the experimental group. This may be a significant pathophysiological factor in clinical malnutrition because of reduction of gastric acid control over bacterial populations in upper intestinal secretions.

Animals↗
PubMed1981

Detection of enterotoxins of Aeromonas hydrophila by a suckling-mouse test.

The suckling-mouse assay was reliable for detecting enterotoxigenic strains of Aeromonas hydrophila when standard conditions for growth and toxin testing were used. Enterotoxins were produced by bacteria grown in tryptone soya broth supplemented with yeast extract and aerated by shaking in an environmental incubator or water bath. When culture supernates together with dye were administered intragastrically to mice less than 6 days old, the presence of enterotoxin was assessed on the basis of a scoring system that incorporated the ratio intestinal weight: remaining body weight, and production of diarrhoea. This method should facilitate the detection of enterotoxigenic strains of Aeromonas in epidemiological studies.

Aeromonas↗