Friday, November 17, 2006

VTEC 2006

A short summary of what I got out of the meeting. Please note any mistakes and misinterpratations are mine not the Speakers

Conference report
Dr Mohamed Karmali:
Key note speaker ‘poetry in motion”
A general and fairly light introduction into the whole area and reviewed the subject in not a great deal of detail but there were enough bits of interest for everyone.
A couple of points that were of interest to me were that D. mellitus is a fairly common complication of the toxin associated disease. I am unclear what this tells us about toxin disease but it is clearly important in the clinical management of cases. Also important is the rapid diagnosis of the disease and he presented a timeline which we were to see many more times in the conference. It is now widely accepted that there is a day at most between positive diagnosis of EHEC associated disease and the onset of HUS. Dr Karmali used an example of a very confident lab in this example and this highlights the need for a rapid bedside diagnostic test.
Examples of interventions both human and animal were discussed. Fluid Therapy is the mainstay of fighting HUS and is likely to remain so in the near future. Early administration was considered important. Other interventions including those considered for animals were considered inconclusive as to their effects. These interventions included vaccines, antibiotics, bacteriophages and sodium chlorate.

Pat Griffin Epidemiology in the USA
Labs in the US have found the elisa a very useful detection kit ad this is frequently used in the confirmation and tracing of disease.
The source of disease is changing over time and while ground beef (mince to the UK population remains the major source of infection it has been declining in the US since 2004 when the meat industry introduced stricter controls. Another major source is the agricultural fair where young people and animals can come into close contact. Identification of this risk allowed interventions to be put in place and these arte declining.
Produce is an increasing risk as animal faeces are recycled onto the far as fertiliser.

Dr Marta Rivas. Epidemiology in S America.
I won’t repeat the abstract here as I can add little in terms of interpretation or summary but there appears to be a lack of quality epidemiological data coming out of S America although the setting up of the surveillance labs should address this issue. What information there is suggests that the infection risks and sources follows the same pattern as observed elsewhere.

Prof B Reilly Epidemiology in Europe
No notes taken laughing too hard !!!

Dr Xu Epidemiology in Asia
In common with other areas there is an association with cattle but little difference from other areas; however this could be due to my misinterpretation.

M. Doyle transmission of STEC by Food.
There is a difference between the serotypes present within herds and that found in contaminated samples. There fore new models are being developed to account for survival of the various serotypes.
Produce is a growing concern and cutting this produce may increase risk as damage and bruising to the stems and plants will allow protection from any decontaminants applied. These decontaminants are frequently poorly applied or ineffective. Microbiological control of fresh cut produce I particular is very poor. (The closer to the farm the fresher but the risk of microbiological contamination appears to increase.

Geraldine Duffy VTEC transmission in the farming environment.
There is a massive industry use of faecal material in the farming environment and there is an associated contamination problem. This ability to survive may be improved by passage in the gut. Although this contamination is important the contamination from hides through mutual grooming may be as important in horizontal transmission.

Carolyn Hovde. Genes involved in the STEC colonisation of cattle.
The Hovde group appears to favour a rectal administration for testing mutants in the host. The usual suspects were implicated in reducing colonisation. These included eae, TIR, FliC, pO157, the ecf operon and Lpxm.
The rectal administration was used to assess the host response to colonisation. However the sample was retrieved by whole mucosa biopsy. This means that the array is likely to be picking up signals from a variety of layers and cell types and this means the analysis is likely to be complex. The group is focussing in on alterations to the cell cytoskeleton and this may be related to our work.

Desmarchelier P Transmission of STEC in Australia.
Little of difference from other countries however cases were sporadic rather than clustered and sources are rarely identified.

Brett Finlay Pathogenic E. coli contribution of the host pathogen and microbiota.
The lab uses the murine model to study the response of the host to infection. This was nothing that wasn’t repeated by other speakers but the study of the intestinal microbiota in health and disease was new material. 1 subset of the bacterial population was reduced in this pattern. This subset did cover a huge range of species however.

Leong J Nck independent pathways
Both EHEC and EPEC have the ability to activate actin assembly without the use of Nck. This utilises EspFu and another host cell protein that is yet to be identified. ESpFu is not found in EPEC and if artificially induced then the Nck independent pathway, normally very inefficient in the normal infection becomes many time s more efficient.
M Stevens Molecular insights into the carriage and virulence of VTEC in cattle
STM was used to identify genes within the EHEC genome that allow the colonisation of cattle. However although the group has managed to elicit Serum and salivary IgG these responses did not appear to be protective.
Noradrenalin responses did appear to b important in the response to colonisation through quorum sensing though the full impact of these is still under study.

J. Paton Virulence determinants of LEE negative STEC
Subtilase toxin was the main focus of this talk. This is a prototype of A new group of A1B5 subunit toxin. It has demonstrated a greater virulence to Vero cells than shigatoxin. This has been demonstrated in O113. Its mode of action is to cleave BIP, a host protein involved in the folding of proteins at the endoplasmic membrane. This protein also has functions in maintaining membrane permeability and regulation of the ER membrane stress response. BIP has two important domains, an ATPase and a protein binding domain. Subtilase cleaves BIP between these two domains leaving a 28Kd protein fragment.

G Frankel TccPm of VTEC.
TccPm is a protein that is encoded by a lot of VTEC both O157 and non O157. It appears to function as an Nck analogue fulfilling the function of the Nck host protein. This talk was repeated and expanded in the EPEC workshop so I will go into more detail at that point.

Sandvig K. Entry of Shigatoxin into cells.
The entry of the A1 subunit into the cytosol is concentration dependent with high concentrations able to induce the clathrin dependent endocytosis of the toxin. In this respect it is the A subunit that is important, Syk activation appears to be important in the activation of the clathrin mediated endocytosis.
Furin cleaves the subunit in the endosomes to allow activation of the toxin.

Obrig T Mouse model of HUS
A mouse model of HUS was presented at the conference but of little interest to those interested in the actions of the bacteria.

Phillips D Ex vivo human intestinal response to STEC
In vivo experiments were used to examine the balance between six mediated and bacterial mediated disease. Bacterial induced damage appears to be light in the human with more severs disease associated with stx and this may be remote from the site of colonisation. There are STX epitopes on the neuroendocrine cells of the gastrointestinal tract and these must be considered in antibody assays of these regions.

O’Brien A Treatment and prevention of infection with Shigatoxin (STX) producing E coli (STEC).
Description of a shigatoxin mAB therapy, these look to be useful in the future for treatment of humans affected by the toxin. An alterative to this approach is the production of epitopes that bind the STX and remove it from the circulation.
Toxoids are being produced in plant systems and mice are protected following ingesting even when fed the plant.

Potter A. Vaccines for cattle.
A Potter outlined a number of factors that are required in a vaccine. It must be safe effective and cost effective. It must fit into existing management practices and these will vary from region to region. The duration of immunity must cover the length of time required. In the case of E. coli a broad serotype protection is required. Ideally a balanced immune response would be produced.
Vaccines tested utilised Type three secretory proteins but these are serotype specific in an epithelial model system. However the route of vaccination is believed to be important in the reduction of carriage.
An interesting model system was described that can be maintained for extended periods. This will be used to examine the responses to the vaccine.

Tarr P. The Pathophysiology of childhood E.coli infection
The critical aspect in paediatric medicine appears to be the time between initial infection (or appearance of clinical signs) diagnosis and appearance of HUS in the patients that go down with this syndrome. HUS appears to occur on day 5 post infection and diagnosis takes approximately 4 days in a good lab. There for with communication delays or delays in presenting the patient to the care facility may leave the medical facility with only hours to initiate appropriate measures.
Aggressive fluid therapy will remain a critical method for avoiding HUS for the foreseeable future. Antibiotics remain a risk for developing HUS symptoms.

Weigl B.H. Lab on a chip.
The PATH group are producing a PCR based assay that incorporates all the steps from pathogen capture through to detection of the amplicons produced. This technology will be marketed at low resource areas. The technology will also remove the need for skilled personnel at the point of care doing the diagnosis.

This is an initial draft and there is another day to write up as well so any comments can be left here if needed.

The first weekend on call

Its been a week here and I haven't euthanased anything yet. Unheard of! Gina will be pleased especially as I have seen some horses.
I had a snake bite on my first day and it survived probably because I listened to the nurses. i will probably post the dogs photo soon but the connection appears to be very slow today so later this week I think.
I have managed to down load celines Photos from Tasmania and will stitch a few of the together into a post over the weekend.

Snorkelling at Cairns

Seeing as I was not able to dive I thought I would take a day sailing and snorkelling on the Barrier reef.

And I got to put up this sail!! Green Island was a bit of a dissapointment but there was a fishing boat to look at. I think I might buy a boat

Monday, November 13, 2006


Well I finally made it and have unpacked for the last time this year (I hope). Started my first day as a rural vet in NSW. Look forward to lots of vet related tales in the next few weeks. A few new photos as well in the future including the Photographs courtesy of Celine.