Diarrhoea Flashcards

Question

What is LEE?

Answer 1

The locus of enterocyte effacement which codes for both the type 3 secretion system and the effector proteins

Answer 2

EscC is in the outermembrane of the bacteria, the EspA subunit is then taken to the extracellular environment through EscC which remains attached to the EscC protein to build up a needle to reach the host cell Once in the host cell EspD/B attaches the needle to the host cell allowing flow of effector molecules from the bacteria to the host

Answer 3

The translocated initim receptor (Tir) allowing closer attachement of the bacteria to the host Many other proteins allowing for functional redundancy, co-operativity and functional redundancy

Answer 4

There is loss of SGLT1 directly and by effacement of the microvilli Increased activity of Na+/H+ exchanger and decreased activity of H+/Na+ exchanger resulting in decreased Na uptake Decreases in cell surface level of DRA and internalisation via microtubule rearrangement causing reduced Cl- absorption There is a stimulating phosphorylation of myosin light chain leading to disruption of tight junctions and the epithelial barrier Alteration in the phosphorylation status and location of occludin and zona occluding disrupting the barrier function

Answer 5

One of the effector proteins causes a loss if the SGLT1 transporter from the enterocyte which is the key transporter that the therapy relies on

Answer 6

A condition which typically has an incubation period of 1-10 days, developing 7 days after the first symptoms There is anaemia caused by destruction of red blood cells, acute kidney failure and low platelet count with a small proportion of survivors developing chronic kidney disease

Answer 7

It was found to cause the hamburger outbreak in the early 80’s in the USA It has two key weapons in its arsenal which can disrupt gastrointestinal cells without invading it and produces a shiga-like toxin Antibiotics must be used carefully with this strain as if the bacteria is lysed then all the toxin will be released making the disease worse

Answer 8

STx which is the shiga toxin from shigella dysenteriae STx1 which is shiga-like toxin 1 from E. Coli and has a one amino acid difference from STx STx2 which is shiga-like toxin 2 from E. Coli which has a 56% identity with STx and STx1 it is the most common cause of disease

Answer 9

Binds to the specific G3B receptor found on small human blood vessels such as those in the GI tract and kidneys, this receptor is not found in cattle, swine or deer therefore it is not toxic to them and these species can act as reservoirs

Answer 10

STx B subunit binds to GB3 in the cell membrane, the A subunit is then transported to the ER and cleaved by a protease, it then becomes enzymatically active removing a single adenine from 28srRNA inactivating the ribosome causing cell death due to a lack of protein synthesis Or STxB binds to G3B on endothelial cell membranes leading to inactivation of ADAMTS 13 causing multimers of von Willebrands Factor to accumulate on the endothelial cell surface Or STx binds to factor H resulting in persistence of C3b on the host cell

Answer 11

The same serotype of E. Coli O157:H7 which caused the hamburger disease outbreak has also been able to enter inside leaves so they cannot be removed by washing

Answer 12

It was a large and deadly E. Coli outbreak which was unusual as it mainly affected women in their 20’s-40’s and there was a very high rate of Haemorrhagic uraemic syndrome It was not caused by O157:H7 serotype, there was no LEE so it was not a EHEC strain, but it did carry shiga-like toxin 2 and was resistant to multiple classes of antibiotics It was instead a EAEC strain serotyped as O104:H4

Answer 13

It had three additional plasmids with the biggest being similar to those isolated from a horse and having multi-drug resistant genes The smallest codes for two genes one is a DNA replication protein While the middle one coded for aggregative adherence fimbria gene cluster

Diarrhoea Flashcards

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