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Flashcards in L15 Microbiology Of GIT Deck (8)
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1

LO2: desc broad categ of bact in GIT.

-cocci/bacilli. Gram pos/neg. aerob/anaer may be oblig or facult. Some bact form protec endoscopes eg c diff. Bact can stick to surfs using pili/slime.
-gram pos cocci eg s aureus. Gram neg bacilli eg p aeruginosa.
-oblig aerobes- must have O. Pseudomonas and mycobact.
Oblig anaer- die in O eg bactericides fragilis, clostridial orgs form spores.
Facult anaer- pref O can surv w/o. Lot gram neg enteric eg ecoli and gram pos skin dwellers eg staph.
-anaer zones in GIT- parts of mouth eg deep taste buds, fluid films incl biofilm btw teeth, gingival crevice areas and in people with periodontal dis where bact live in periodontal pockets. Also small bowel, colon and stom.
-colonic anaerobes- algae dev photosynth and prod O so near mig to colons.
-dev of cells- an aer bact was taken into a anaer bact and formed an organelle that became mito allow cells and complex to dev.
-endo spores- can resis heat. Eg bacillus anthrax, clostridium tetani.
-bact pili att, eg ecoli to bladder.
-bact slime- eg staph epidermidis. Prosthetic surf- bact att with slime, diffic get rid. Biofilm of slime- AB in blood can't penet, have to rem infected prosthetic eg.
-cocci- gram pos aer eg staph, strep, enterococcus. Gram neg aer eg N mening and gonorrhoeae.
-bacilli- gram pos anaer- clostridium tatani, perfringens and difficile. Gram pos aer eg corynebacterium (diptheria), Bacillus anthrax, lactobacillus, mTB.
Gram neg enteric anaer eg bactericides fragilis- 98% colonic bact. Aerobic- ecoli, pseudomonas, proteus, klebsiella, salmonella, shigella, vibrio cholerae, campylobacter, H pylori.
Gram neg non enteric- aerobic eg H influenzae= pneum/mening, bordetella pertussis, brucella.

2

LO3: desc comm causes for range of GI infecs.

-Mouth- anaerobes. Strep, staph, candida, lactobacillus, enterococcus (700 sp been id'd in mouth). Human bites can cause bad infec.
Mouth bact can cause tiss destruc if indiv is maln, dehyd, immcomprom or systemically unwell. No a/cancrum oris eats away at mouth tiss.
-Oral thrush due to Candida albicans. AB alt bact flora of mouth=candida flourish, also gen unwell, dehyd etc. RFs- newborns, DM, AB, inhaled steroids decr loc imm in mouth, imm defic.
Tx- amphotericin lozenges. Nystatin suspension. Signs- candida red tongue. Angular cheilocis iron defic and candida.
-dental caries/gingivitis- teeth colon by mouth bact plus S mutants.

3

LO4: disc comm causes of travellers diarr.

-many travellers stuff gastroenteritis esp in dev countries. Sev diarr though organism not id'd.

4

LO5: desc causes of int inflamm and infec.

-P aeruginosa- prod green pus bad smell. Love moisture. Venous ulcers leak fluid. Also eg led incontin.
Pseudomonas can contam cleaning prod. Static fluid risk.
-clostridia- tetani (drum stick app as endospores)-tetanus, some people intermittent carry in colon. Difficile- pseudomembranous colitis. Perfringens- gas/wet gangrene.
Neonatal tetanus kills 60000/yr. eld no vacc or expos to horse manure. Musc spasm, lock jaw prod risks sardonicus. Opisthotonus termin event resp musc spasm comm larynx.
-clostrid perfringens- anaer dig of gluc= ethanol and co2 so wet or gas gangrene. Gas in tiss prod sev cardio toxin, amput v quick. Eg trenches full faeces and inj. Gas gangrene eg diab pt, tox shock, spreading subcut blueness as organism eat anaer, must rem all tiss.
Pro tonsil 1st commercial avail AB 1935.
-ev yr epidemics of vir vom and diarr.
-gastroenteritis contam food or drink. Ingest org or toxin often bact origins already in food. Toxins effs in hours, org up to 48hr. Most comm orgs salmonella, campylobacter, listeria. Comm toxins staph or clostrid. Hosp c diff big prob as poor health anyway.
-cholera sev acute infec endemic lot countries often occs as epidemics eg nat disasters. Surfs in water. Effs ileum= massive water and salt into lumen by active sec. Rice water stool= int secs and muc. Repl water and electrolytes.
-int parasites. Some protozoans eg giardia and cryptosporidium cause gastroenteritis. Other helminth infest can cause malabs etc.

5

LO1: desc role bact in supp norm func of GIT.

-hum 10^16 bact vs 10^15 cells. Maj in colon. 800 bact on/in bod. 10^14 in GIT.
-hum colonic bact- synth and excrete vits that are abs by host eg vitK, B12, thiamine etc. Prev colonisat by pathogens, eg c diff destr norm microbiota. Kill non indigenous bact. Stim dev of MALT in caecum and PPs. Stim prod nat Abs.
Germ free animus have vit defic esp K and B12. Incr suscep infec dis. Poor imm sys esp in GIT. Lack nat Ab or nat imm to bact infec. Faecal transl- gut microbes aff weight and neurol?

6

LO3: throat etc

-Ludwigs angina us streptococcal. Small propor with strep tonsillitis/throat- bugs mig to LN become infec=neck cellulitis=press on larynx can=asphyx.
-parotitis caused by staph aureus- 20% mort. Parot fascia not swell=pain.
-nose- staph and strep etc. 1 of 3 sites of MRSA screen swabs. Nose, throat and perineum.
-throat bact/fungi- strep viridans in all people, strep pyogenes, s pneum, staph, N mening also in ev, H influ, lactobacilli, corynebacterium diptheriae, Candida albicans.
-strep viridans- non pathog throat commensal. Dur proceds eg teeth brush, dental proceds, gen anaesthesia it may ent blood- bacteraemia temp. May stick to prosthesis eg heart valves, vasc grafts, orthopaedic impl as have no def.
-bacteraemia- bact rap cleared from blood by liv/spleen Mac. Blood cult would be pos. No symps prod.
Septicaemia- bact not cleared and multip in blood stream, sepsis symps dev. Need recog early.
-lot LT and mouth as maj pt ent GI and RT. Lingual and palatine tonsil.
-tonsillitis- 70% viral- adenovirus, rhinovir, EBV. 30% bact mainly S pyogenes (beta haemolytic). Need disting to know if give AB.
-quinsy- tonsillitis formed access in tonsil. Resp stridor and panic, need let pus out, avoid int carotid art, fast relief. Can cause deviated uvula.

7

LO3: oesoph and stom and colon.

-oesoph candidiasis. Pain swall.
-stom H pylori- curved bacillus. Warren and marshal.
H pylori- at east 50% pop infected. 10-12% of infected get gastric or duod ulcers. is assoc with 90% of duod and 70% gastric ulcers. Ranitidine and PPI's mean don't do gastrectomy for gastric ulcer.
-colonic bact- over 100 sp regul exist. 95-9% anaer esp bacteroides fragilis gram neg non spore form, and clostridium sp eg perfringens gram pos spore forming. both anaer bacilli.
-bact always in colon- bacteroides fragilis and oralis and melaninogenicus 95-99%. E. coli. Enterococcus faecalis.
Other gram neg aer enteric eg pseudomonas, proteus, klebsiella, salmonella, shigella, vibrio cholerae, campylobacter. Gram pos aer lactobacillus.
-enteric bact and surg- gut surg dirty surg. High risk wound infec. SI/stom norm no bact excep h pylori. Comm wound infec and dehiscence. Prophyl AB to reduce- need cover anaerobes, gram neg bacilli, gram pos cocci. Metronidazole kills anaer so one regimen is this plus a broad spectrum AB eg gentamicin or cephalosporin. Regimes const change. Alt regimen is co amoxyclav (augmentin) a penicillin- kill gram pos and neg anaer, can kill peop if allerg. Adhere to local policy.

8

LO3: rectum etc.

-faecal peritonitis- 50% mort even if fit and yng. Colonic muc protec not in perit so ent blood, overwhelm fast.
Eg eld divertic dis=sigm burst, or stab wound.
-anal gl- gl blocking eg faecoliths=bugs prolif. Intrinsic anal canal sampling tell what subst is. Veins submuc so incr press=swell. Veins norm serosa. Perianal access-gl with anaerobes in.
-colonic bact on perineal skin- bacteroides can't surv O. E. coli can surv as can enterococcus faecalis and lactobacillus- are facult anaer.
-lactobacillus- norm vaginal commensal. Conv glycog to lactic ac. Acid env prevs other bact and Candida albicans grow. Gram pos. L acidophilus can lead to thrush. Broad AB kills.
-90% UTIs in wom as close ent to bladd from rectum. 75% ecoli, then enterococcus faecalis. After that var gram neg enteric bacilli eg klebsiella, proteus, pseudomonas- unus so ? Bladd tumour etc.
- relev of urgent MSU gram stain in pt with lower abdo pain. UTI or append?
Gram neg bacilli ecoli and Gram pos cocci enterococcus sig UTI.
Gram pos bacilli eg lactobacillus probab contam urine sample, and gram neg cocci eg gonococus (causes urethritis not UTI) not Indic UTI. 48hr lab cult, need to decide faster than that.