Flashcards in Infectious Diseases GI Deck (68):
What immune system eliminates most of the intestinal infection?
The Innate Immune System
What is the mechanism of the innate immune system?
Membrane attack complex
Activation through ligation of pattern recognition receptors (Toll-like receptors)
Intracellular receptors signal via NFkB pathway
What does signalling via the NFkB system do to the cell?
It causes t he cell it become activated.
Secretion of Chemokines, defensins, cytokines
What determines the outcome of the infection?
Too strong an immune response will cause damage to the body. e.g. crohn's or ulcerative colitis
Too little an immune response and the pathogen will not be removed
What is diarrhoea?
No other cause
Stool holds shape on container
How can you assess the stool?
Bristol stool chart
What is food poisoning?
Illness cases by eating contained food - with micoorganisms.
What organisms cause food poisoning?
Campylobacter - most common food poisoning
Salmonella - In immunosuppressed patients (second most common)
What is the incubation time of staph aureus/ bacillus cereus
What is the incubation time for salmonella?
What is the incubation time of campylobacter?
Does not spread person to person easily
How is campylobacter treated?
What is the most common form of salmonella?
How is salmonella treated?
How is salmonella typed?
- anti-body produces that detects specific antigen. The body of lamella has the O antigen, and the tail has the H antigen.
Antigen agglutinates with the corresponding antibody
What is the sign for e coli ?
- there is person to person and direct/indirect contamination
What toxin does e coli 0157 produce?
What are signs of coli 0157?
What syndrome can coli 0157 cause?
Haemolytic uraemic sydnrome
- caused by Verotoxin. Appears when the diarrhoea is clearing
What does Verotoxin do?
Binds to receptors on renal cells and red blood cells.
This inhibits protein synthesis - causes cell death
How can HUS be detected?
Acute renal failure
What tests are done for HUS?
U and E
What is the management of HUS?
No anti-motility agents
How is Ecoli 0157 diagnosed?
Selective culture - use of sortbitol sugar, which Ecoli 0157 doesn't use. (The selective culture should turn from organ to pink, if it doesn't - it is 0157 )
Detection of Verotoxin
What is an antibiotic?
A substance that kills or inhibits the growth of a mircoorganism
What is susceptible mean?
arbitrary designation that implies that an antimicrobial will inhibit bacterial growth at clinically achievable concentrations
What does MDR bacteria mean?
non-susceptibility to at least 1 agent in 3 or more antimicrobial categories
What does XDR bacteria mean?
non-susceptibility to at least 1 agent in all but 2 or fewer antimicrobial categories (ie, bacterial isolates remain susceptible to only 1 or 2 categories)
What does PDR bacteria mean?
non-susceptibility to all agents in all antimicrobial categories(ie, no agents tested as susceptible for that organism)
How do beta-lactams work?
Attack the protein wall by acting on the penicillin binding proteins - this will break up the cell wall
What are the beta lactase?
Penicillins: amoxil, coamoxiclav, piperacilli-tazpbactam
How does ciprafloxacin work?
Works on the DNA
What drives antimicrobial resistance?
May have resistance already
Bacteria can transfer DNA via plasmid transfer
What are the methods of microbial resistance?
Altering the target site of the antibiotic
Preventing access to the target site
Inactivating the antibiotic
What are the multi-drugs resistant bacteria?
What is the increased risk of resistance once your prescribe something and it comes back?
2 fold increase of resistance.
what are the basic principals of treating a pathogen?
Define the pathogen
Treat the patient - not the culture
Match aggressive Rx to severity
Find the source e.g. drains, pus. (always remove pus)
What type of antibiotic will cause resistance?
Broad spectrum antibiotic
Antibiotics given for too long
Low doses of antibiotics
What is acute traveller's diarrhoea?
3 loose stools in 24 hours
Associated with fever
What causes Acute traveller's diarrhoea generally?
What pathogen is associated with bloody diarrhoea / dysentery?
What pathogen is associated with profuse watery diarrhoea?
What test is done for acute traveller's diarrhoea?
What is the treatment for acute traveller's diarrhoea?
Fluroquinolone is helpful
If not it will resolve itself
What bacteria causes Typhoid?
What are the investigations that should be carried out for jaundice and fever, after traveling?
Malaria blood film and rapid antigen
Blood film for red cell fragmentation
Serological testing for viruses
What pathogens may cause jaundice and fever?
Sickle cell crisis
What are the symptoms for inta-abdominal infection?
Constipation or diarrhoea
What is SIRS ?
Systemic Inflammatory Response Syndrome.
A non-sepcific clinical response:
Pulse > 90
White cell count > 12000
(Not all SIRS is related to Infection)
What is Sepsis?
Systemic Inflammatory response + Suspected Infection
What is the disease continuum of sepsis?
How do you investigate sepsis?
Full Blood count
How do you treat sepsis?
What test helps tests for past diseases?
What is Bacteraemia?
Blood stream infection
What are the community acquired infections that cause Bacteraemia?
What are the hospital acquired infections that cause bacteraemia?
Psuedomonas (typically in oncological malignancy)
What type of bacteria is Pseudomonas?
What bacteria generally affect the mouth?
Strep. “viridans”, Neisseria sp., anaerobes
Candida sp. (few), Staphylococci
What bacteria generally affect the stomach/duodenum?
Few Candida sp. & Staphylococci may survive
Helicobacteria Pylori for peptic ulcers
What bacteria generally affect the jejunum?
Small numbers of coliforms and anaerobes
What bacteria generally affect the colon?
Large numbers of coliforms anaerobes and Enterococcus faecalis
What antibiotic is used for gram positive bacteria?
e.g. for steptococci and enterococci
What antibiotic is used for coliforms?
What antibiotic is used for anaerobes and bactericides?
What are the side effects of gentamicin?
Kidney and hearing problems
Treatment is typically only 72 hours to prevent problems
What is septic shock?
Severe sepsis with hypotension even with adequate administer fluids or requiring vasopressors or inotropes