17 research outputs found
PATHOGENICITY OF VIBRIO ANGUILLARUM IN FISH
This dissertation. reports the first detailed study of the
possible pathogenic mechanisms and virulence determinants of the
fish pathogen V. anguillarum carried out in association with histo-pathological
studies using electron microscopy and electrocardiography
In addition, possible infection route (s) were investigated and the
effect of environmental variables on pathogenesis examined.
Pathogenicity was found to be species specific with strains
which were avirulent in eels being highly virulent in grey mullet.
Following injection of virulent bacteria into eels all tissues were
rapidly colonised, death being characterised by severe haemorrhagic
septicaemia. In contrast, avirulent strains were rapidly eliminated
from the eel host to levels below detection. The heart was particularly
affected during pathogenesis. Vibriosis was found to be temperature
related, disease being retarded by low temperature.
Pathogenic properties investigated included production of
enzymes and haemolysins and examined in vitro phagocytosis and
growth rates. Membrane proteins were extracted by various techniques
and separated using SDS-polyacrylamide electrophoresis thereby
elucidating interstrain variation in protein profile, most strains
containing a major outer membrane protein thought to be a porin.
Ultrastructural studies revealed some bacteria to have up to three
polar flagella per cell, with multiflagellate forms only being
observed in virulent strains. Analysis of plasmid DNA revealed a
partial correlation between possession of a 47 megadalton plasmid
and colistin resistance.
Experimental vibriosis was characterised by deposition of
haemosiderin in liver tissues, thought to be a poorly studied host
defence mechanism, and large numbers of tissue bacteria surrounded
by an electron lucent zone which was non-capsular in nature. Features
of the disease included desquamation of the intestinal mucosa with
excessive loss of ions into the gut lumen.
The most likly route of infection was thought to be via the
gut, as osmoregulatory processes provided a direct means for waterborne
V. anguillarum to enter the gut, to which this bacterium was
found to be particularly well adapted. Gut traversal was thought to
be the precursor to a possible latent infection in the kidney
Methods In:Practical Laboratory Bacteriology
xiii,151 hal,;ill,;30 c
Serodiagnosis of Salmonella enterica serovar Typhi and S. enterica serovars Paratyphi A, B and C human infections
The aim of this study was to evaluate an immunoassay for the detection of human serum antibodies to the LPS and flagellar antigens of Salmonella Typhi and Salmonella Paratyphi A, B and C, and to the Vi capsular polysaccharide of S. Typhi and S. Paratyphi C. A total of 330 sera were used; these originated from 15 patients who were culture-positive for S. Typhi and 15 healthy controls, together with 300 sera submitted to the Laboratory of Enteric Pathogens for Salmonella serodiagnosis. By SDS-PAGE/immunoblotting, all 15 sera from culture-positive patients had serum antibodies to the 9,12 LPS antigens and 10 had antibodies to the ‘d’ flagellar antigens. Of the 300 reference sera, 22 had antibodies to the 9,12 LPS antigens, one to the 1,4,5,12 LPS antigens and 12 to the 6,7 LPS antigens. Only two sera had antibodies to flagellar antigens, one of which bound to the ‘b’ and the other to the ‘d’ antigen. An ELISA was developed that successfully detected serum antibodies to the Vi capsular polysaccharides, but because of the kinetics of serum antibody production to the Vi, these antibodies may be of limited value in the serodiagnosis of acute infection with S. Typhi and S. Paratyphi C. The immunoassays described here provide a sensitive means of detecting serum antibodies to the LPS, flagellar and Vi antigens of S. Typhi and S. Paratyphi, and constitute a viable replacement for the Widal assay for the screening of sera. The Salmonella serodiagnosis protocols described here are the new standard operating procedures used by the Health Protection Agency's National Salmonella Reference Centre based in the Laboratory of Enteric Pathogens, Colindale, UK
The Relationship between aerobic fitness and recovery from high intensity intermittent exercise
Hemolytic uremic syndrome (HUS), the leading cause of acute renal failure in childhood, can be caused by different serotypes of vero cytotoxin (VT; i.e., Shiga toxin)-producing Escherichia coli (VTEC). Recently, VT was shown to bind to polymorphonuclear leukocytes (PMNL) in the systemic circulation of patients with HUS. This study investigated whether VT bound to PMNL could be detected in persons in households with patients with HUS. Serum antibodies against E. coli O157 and, when available, fecal samples from patients with HUS and household members were studied for the presence of VTEC infection. The circulating PMNL of 82% of the household members were positive for VT, whereas stool and/or serum examination showed only 21% positivity. Thus, current methods underestimate the number of infected persons in households with patients with HUS