GI Infections Flashcards
(258 cards)
1
Q
What are main issues that are contributed to antibiotic resistance?
A
- Underdosing or not completing courses
- Use with livestock
- Selling them over the counter in some european countries
- Possibly using the prophylactically before surgery
- Releasing large quantities of antibiotics into the environment during pharmaceutical manufacturing
2
Q
What is the definition of antimicrobial resistance (AMR)?
A
Implies that an antimicrobial will not inhibit bacterial growth at clinically achievable concentrations
3
Q
What is the definition of antimicrobial susceptibility?
A
Implies that an antimicrobial will inhibit bacterial growth at clinically achievable concentrations
4
Q
What is the laboratory effect of resistance?
A
If resistant in the lab, will more often than not translate into clinical environments
5
Q
What is MDR?
A
Multidrug resistance: non-susceptibility to at least 1 agent in 3 or more antimicrobial categories
6
Q
What is XDR?
A
Extensively-Drug resistant: non-susceptibility to at least 1 agent in all but 2 or fewer antimicrobial categories
7
Q
What is PDR?
A
PanDrug resistance: non-susceptibility to all agents in all antimicrobial categories (no agents can fight the buggers)
8
Q
What are the 2 types of resistance?
A
Innate or acquired (majority)
9
Q
What are the 6 main mechanism of resistance?
A
1) Inactivation
2) Impermeability
3) Efflux
4) By-pass
5) Pbps • Penicilan binding proteins which change the structure, so that there isn’t a perfect lock of the antibiotics to the microbe
6) Altered target
10
Q
What are the 3 mechanisms by which bacteria can transfer the resistant genes?
A
- Bacterial transformation (direct uptake)
- Bacterial transduction (via a virus)
- Bacterial conjugation (through mating)
11
Q
What are the 4 main solutions to reducing AMR?
A
- Preventing infections and preventing spread of disease
- Tracking these resistant bugs
- Improving antibiotic prescribing and use, aka stewardship
- Developing new drugs
12
Q
What is antimicrobial stewardship?
A
The optimal selection, dosage, and duration of antimicrobial treatment that results in the best clinical outcome for the treatment or prevention of infection, with minimal toxicity to the patient and minimal impact on subsequent resistance
13
Q
What are the 4 D’s of antimicrobial stewardship?
A
Dose, Duration, Drug and De-escalation
14
Q
In terms of prescribing, what things must be addressed to reduce resistance?
A
- Broad spectrum antibiotic therapy (choose combination of narrow spectrum instead)
- Long duration of therapy (give for as short as possible)
- Low or suboptimal dose of antibiotic
- Route of therapy makes no difference IV vs Oral)
- Total amount of antibiotic use
- Giving antibiotic in the absence of infection
15
Q
What are host factors that increase risk of GI infections?
A
- Age (very young & elderly)
- ↓ gastric acid secretion
- ↓ gut motility
- Influence of colonic microflora
- Altered intestinal immunity
16
Q
What is the definition of diarrhoea?
A
3 or more loose stools in 24 hours
17
Q
What kind of bacteria is campylobacter (c. jejuni or c. coli)?
A
Gram negative bacillus
18
Q
What is the incubation period of campylobacter?
A
3-10 days
19
Q
What is the commonest cause of bacterial GI infection in the UK?
A
Campylobacter
20
Q
What is the mechanism of action of campylobacter?
A
Causes inflammation of colon and rectum→bloody diarrhoea
21
Q
What is the source/vehicle of infection of campylobacter?
A
Farm animals - especially undercooked poultry, but also water and unpasteurised milk
22
Q
What is the management of unresolved campylobacter with systemic illness?
A
Erythromycin or ciprafloxin for 5 days
23
Q
What is the incubation period of salmonella enterica?
A
Medium - 12-48hrs
24
Q
What is the mechanism of action of salmonella enterica?
A
Causes inflammation of ileum and colon – cause mucosal damage, ↓fluid absorption and ↑fluid excretion • Which is what causes the loose stools and diarrhoea
25
What is the source/vehicle of infection of salmonella enterica?
Farm animals, esp. undercooked poultry
26
What is the management of unresolved salmonella enterica with systemic illness?
Ciprafloxin for 5 days
27
Which is the only shigella species seen in the UK?
Shigella sonnei
28
What is the incubation period for shigella?
1-9 days
29
True or false: campylobacter and salmonella can enter bloodstream
True
30
True or false: shigella can enter bloodstream
False (never seen on blood cultures)
31
What is the vehicle of infection of shigella?
Human only infection - common in children
32
What is the mechanism of action of Ecoli 0157?
The 0157 strain produces a verotoxin (VTEC) which that damages red cells and the kidney, causing haemolytic-uraemic syndrome (HUS)
33
What is the commonest cause of renal failure in children
E coli 0157
34
What is the source of E Coli 0157?
Carried as normal gut flora in cattle - Beef becomes contaminated on the outside at slaughter
35
What is the vehicle of infection for e coli 0157?
- Contact with cattle, private (untreated) water supplies – run off water from fields and undercooked mince and hamburgers
36
Is the infectious dose for E coli 0157 low or high?
Low
37
Does management of E coli involve antibiotics?
No, as this may increase release of toxin. Supportive and symptomatic treatment only with monitoring for HUS
38
What is the clinical presentation of HUS?
* Abdo pain,
* Fever, pallor
* Petechiae (haemorrhages in skin)
* Oliguria (↓urine production)
39
True or False: Most HUS cases are in those under the age of 16
True (85%)
40
When is the peak presentation of HUS (and therefore when should you test for it)?
7-10 days after onset of diarrhoea
41
What would blood tests show with HUS?
* High white cells
* Low platelets
* Low HB
* Red cell fragments
* Lactate dehydrogenase ↑\>1.5 x normal
42
Which bacteria cause typhoid/paratyphoid fever?
Salmonella typhi/paratyphi A & B
43
Typhoid/paratyphoid fever are examples of febrile illnesses initially, what does this mean?
Circulate in bloodstream first causing headache, flu-like symptoms followed by diarrhoea 3 weeks later
44
What is the incubation period for Typhoid/paratyphoid fever ?
Long - 14-21 days
45
What is the mechanism of action for Typhoid/paratyphoid fever?
Organism invades from gut lumen→lymphatic system→ bloodstream→reticuloendothelial system & gallbladder→gut lumen and invades Peyer’s patches.
46
What is the vehicle of infection of Typhoid/paratyphoid fever?
Human only - drinking contaminated water/food, poor sanitation
47
What are the symptoms of Typhoid/paratyphoid fever?
Fever, rash on abdomen (“Rose spots”), headache, dry cough and diarrhoea
48
What is the management of Typhoid/paratyphoid fever?
Antibiotics - depending on sensitivities. IV Ceftriaxone if unstable
49
Which bacteria causes cholera?
Vibrio cholerae
50
When are outbreaks of cholera common?
War or disaster situations
51
What is the incubation period for cholera?
1-9 days
52
What is the mechanism of action of cholera?
Organism produces an exotoxin that causes active outpouring of fluid from cells of small intestine, resulting in severe watery diarrhoea
53
What is the source/vehicle of infection of cholera?
Human only - drinking contaminated water/poor sanitation
54
Rice water stools
Cholera
55
What is the management of cholera?
Fluid and electrolyte replacement. NOT antibiotics (will increase toxin release)
56
Which infections are associated with pre-formed toxins?
Staph aureus, clostridium perfingens, bacileus cereus
57
What is the classic food associated with staph aureus infection?
Cream cake touched by infected baker (aureus apparently soudns like oreo..which has cream in the middle)
58
What is the mechanism of action of staph aureus?
Staph aureus releases entero toxin → Toxin adsorbed quickly→acts directly on vagus nerve & vomiting centre→vomiting within 1-2 hours
59
What is the source of clostridium perfringens?
Part of normal gut flora of humans and animals
60
What bacteria is meat gravy classically associated with?
Clostridium perfringens (because if you dont keep the gravy in the fridge...perFRINGens, get it?)
61
What is vehicle of transport of clostridium perfringens?
Spores survive cooking, then turn into vegetative organisms, some strains of which produce enterotoxin (an exotoxin)
62
What is the mechanism of action of bacillus cereus?
Exotoxin ingested as pre-formed toxin or organism can multiply in intestine. Spores survive cooking, then turn into vegetative organisms, some strains of which produce enterotoxin (an exotoxin)
63
What bacteria is uncooked rice classically associated with?
Bacillus cereus (becuase cereus sounds like rice...apparently)
64
Which bacteria have short incubation periods (1-6hrs)?
staph aureus, bacillus cereus
65
Which bacteria have medium incubation periods (12-48hrs)?
Salmonella/Cl perfringens
66
Which bacteria have long incubation periods (2-14days)?
Campylobacter/E coli 0157)
67
What kind of infection is cryptosporidium?
Protozoal
68
What is the mechanism of action of cryptosporidium?
Infection occurs when cysts are ingested which “hatch” into trophozoites that invade the cells of the small intestine
69
What is the source of cryptosporidium?
Domestic animals, especially calves
70
What is the vehicle of infection of cryptosporidium?
Person-person spread. Outbreaks associated with contaminated water supplies & swimming pools (cysts resistant to chlorine
71
In which group of patients is cryptosporidium particularly severe?
HIV positive
72
What is the investigation for cryptosporidium?
modified Ziehl-Neelson stain
73
What is the mechanism of action for giardia lamblia?
Infection occurs when cysts are ingested which “hatch” into trophozoites that invade the cells of the upper small intestine
74
What is the vehicle of infection for giardia lamblia?
Person to person - associated with contaminated water
75
What are the symptoms of giardia lamblia?
Diarrhoea, malabsorption syndrome, anorexia, abdominal pain, flatulence
76
What is the management for Giardia lamblia?
Oral metronidazole
77
What are Enterobius vermicularis also known as?
Threadworms
78
What is the pathogenesis for threadworms?
Ova (eggs) ingested→hatch in intestine and live in caecum & colon→adult females come out on to perianal skin at night and lay ova→ova cause perianal itch→child scratches bottom→puts fingers in mouth
79
What is the vehicle of infection of threadworms?
Human only - poor hygiene
80
What are the symptoms of threadworms?
Perianal itch, worms seen in stool
81
What is the management for threadworms?
Oral mebendazole. Often have to treat all members of family at once
82
Who is responsible for monitoring GI infections, potential outbreaks and sending environmental health officers?
Health Protection Teams
83
A patient has diarrhoea whist admitted to hospital - what are you considering.?
C. Difficile
84
In what group of people is C. Difficile rarely seen and why?
Rarely see it in children however, as children don’t have receptors in their gut for the toxins, even though they carry it
85
What is the mechanism of action of C. Difficile?
Organism produces 2 toxins:
* Toxin A (enterotoxin – damages the gut)
* Toxin B (cytotoxin - damaging cells on the epithelium of gut).
This causes colitis (infection of the colon)
86
What is the source of C. Difficile?
Part of normal gut flora. • Infection occurs when antibiotics are prescribed that kill off normal competitive bowel flora and allows C diff to overgrow.
87
What is the vehicle of infection of C. Difficile?
Human to human/and spore ingestion - Organism produces spores that survive in the environment and are more resistant to disinfectants and the organism CAN be transmitted from one patient to another.
88
What is C. Difficile fundamentally?
A colitis
89
What can C. Difficile sometimes progress to?
Pseudomembranous colitis
90
What is the management for less severe C. Difficile?
Oral metronidazole
91
What is the management for severe C. Difficile?
Oral vancomycin
92
What are the 4C antibiotics of C Difficile?
Clindamycin, cephalosporin, co-amoxiclav and ciprofloxacin
93
What type of bacteria is C. Difficile?
Gram positive spore-bearing bacillus
94
How would the lab test for C. diff?
No one good lab test.
1. Screening test for presence of the organism (GDH test)
2. If GDH positive, test for presence of toxin (toxin A&B)
3. (Culture can be done if strain needs to be typed – not done routinely)
95
What does it mean if the screening test for C. difficile is positive and the toxin test is negative?
Indeterminate result - need to assess patient as send repeat specimen
96
Which two virus are the main ones for causing diarrhoea?
Rotovirus and norovirus
97
What is the commonest cause of D&V in children
Rotovirus
98
How is rotavirus spread?
Person-person spread, direct or indirect
99
True or False: Rotavirus and Norovirus cause bloody diarrhoea
False, they dont cause blood
100
Is the infectious dose of rotoavirus low or high?
Low
101
What is the mechanism of action of rotavirus?
↓ absorption of fluids and ↑secretion in bowel, causing dehydration and diarrhoea
102
How is rotavirus diagnosed?
Diagnosis by PCR test on faeces
103
What is the management of rotavirus?
Self-limiting usually within 1 week, so rehydration is key. Vaccine can be preventative
104
Which virus can affect all ages?
Norovirus (rotavirus is mostly children)
105
What is the mode of transmission of noravirus?
- Faecal-oral/droplet routes of spread (spewing in wards = bad) - Person to person (or on contaminated food/water)
106
Why doesnt immunity to norovirus last?
Virus also mutates every few years
107
Is the incubation period for norovirus short or long?
Short (
108
How long does norovirus normally last for?
2-4 days
109
How is norovirus diagnosed?
Faeces specimen or vomit swab for PCR test
110
What is the management for norovirus?
Rehydration is key, esp. young, elderly. Prevent outbreaks
111
What occurs following cessation of symptoms in norovirus?
Asymptomatic shedding occurs for up to 48 hours
112
What is the classic infectious outbreak for cruise ships?
Norovirus
113
Which infections require the patient to be in a side room?
All diarrhoea patients, but particularly C. Difficile and Norovirus
114
Which infections have particularly low infectious doses?
Viruses and E Coli O157
115
By which route are most GI infections transmitted?
Faecal-oral route (poor sanitation, kitchen factors)
116
True or False: Salmonella is more common to cause bloody diarrhoea than Campylobacter and E coli
False, bloody diarrhoea is more rare in salmonella compared to the other two
117
At which point would you normally notify public health about GI infections (except for E coli)?
When you get a positive result from the local lab
118
How is E Coli O157 diagnosed?
Culture or toxin testing in the stool
119
What does the O in O157 stand for?
The surface antigen on E coli
120
What are the most useful test for HUS?
FBC and blood film, and U&Es
121
Which kind of bacteria are staphylococci?
Gram positive cocci in clusters
122
Which kind of bacteria are E Coli (and other coliform)?
Gram negative bacilli
123
Where do penicillins and cephalosporins act on bacteria and how?
Act on the bacterial cell wall by preventing cross-linking of peptidoglycan which weakens the wall and causes them to rupture under pressure
124
What is gastroenteritis?
Inflammation of the stomach and small intestine (Gastritis is jus the stomach and enteritis is just the small intestine)
125
What is the pathophysiology of gastroenteritis?
Inflammation of stomach or intestines inhibits nutrient absorption and excessive H2O and electrolyte loss
126
What kind of infections causes the majority of gastroenteritis?
Viruses
127
True or False: Food poisoning is a subtype pf gastroenteritis
True, it is gastroenteritis resulting from ingestion of contaminated food
128
What is the general onset of food poisoning?
1-6hrs (pre-made toxin so doesnt need time to replicate etc)
129
How long does it normally take food poisoning to resolve?
6-10hrs
130
What actually is food poisoning?
Food poisoning is illness caused by ingestion of food or water contaminated with bacteria and/or their toxins, viruses, parasites, or chemicals. Contamination usually arises from improper handling, preparation, or storage of food or drinks
131
Why is food poisoning rapidly emerging in industrialised countries?
* Poor sanitation & hygiene
* Commercialisation of food production and food service (poor hygiene); big change in eating habits
* Importation of food from developing countries
* Increase in day-care centre attendance
* Increase in institutions that care for the elderly
* International travel, contact with animals/reptiles
* Role of acid suppression, age and immunosuppressive drugs
* People have more weird pets
132
What are the 3 presenting clinical syndromes of food poisoning?
1. Acute enteritis (e.g. salmonella): fever. D&V, abdominal pain
2. Acute colitis (e.g. campylobacter): fever, pain, bloody diarrhoea
3. Enteric fever like illness (e.g. typhoid): fever, rigors, pain but little diarrhoea
133
How long does camplybacter infection generally last?
5-14 days
134
What is a rare but important complication of Campylobacter?
Guillian-Bare Syndrome
135
What is Guillian-Bare Syndrome?
Tingling of the feet leads to progressive paralysis of the legs, arms and rest of the body
136
What is the key to diagnosis of typhoid fever?
Blood cultures
137
Which risk factors put patients at particular risk of recurrent infections and c. difficile?
* Administration of antibiotics after initial treatment of CDI
* Prolonged hospitalization or stay in long-term care facility (LTCF)
* Defective immune response to toxin A
* Gastric acid suppression
138
With diarrhoea pts, what should you ask about in particular with medication history?
Recent antibiotics and PPIs
139
What are the drivers for C. difficile infection?
A. Broad spectrum antbiotic therapy
B. Specific antibiotic types e.g 4C's
C. Long duration of therapy
D. Vulenrable population e.g elderly, nursing home, co-morbidities, hospitalised
F. Total amount of antibiotic use – number of exposures
G. Giving antibiotic in the absence of infection
140
Which 3 organisms are particularly associated with traveller's diarrhoea?
- Amoebiasis - Giardiasis - Cryptosporidiosis
141
What is the average duration of traveller's diarrhoea?
4 days
142
What is amoebiasis and its route of infection?
Protozoal infection spread by faeco-oral route or by an ill or asymptomatic carrier
143
How is amoebiasis diagnosed?
By examination of hot stool for ova and cysts (I dont think so pal)
144
What is the treatment of amoebiasis?
Metronidazole, and remove from lumen with diloxanide furoate or paromomycin
145
How are giardiasis and cryptosporidiosis diagnosed?
Duodenal aspiration
146
Which part of the bowel does amoebiasis mostly affect?
Large bowel
147
Which part of the bowel does giardiasis mostly affect?
Small bowel
148
Which part of the bowel does cryptosproidosis mostly affect?
Small bowel
149
What are the 6 main ways that infections can be transmitted during sex?
1) Direct inoculation (eg. Herpe simplex)
2) Trauma (eg. HCV)
3) IVDU (eg. HIV)
4) Fomites- inanimate objects (eg. gonorrhoea)
5) Ingestion (eg. shigella)
6) Sexual/genital secretions
150
Which bacteria causes rectal gonorrhea?
Neisseria gonorrhoea
151
How is gonorrhea and chlamydia transmitted?
Direct contact of mucosal surfaces. So for proctitis: sex, transmucosal spread, fomite
152
Is the incubation period for gonorrhea short or long?
Short (5-10 days)
153
What are the symptoms for rectal gonorrhea?
Asymptomatic or Low abdo pain, diarrhoea, rectal bleeding, anal discharge, tenesmus
154
What would be seen on proctoscopy with rectal gonnorhea?
Inflamed mucosal and purulent exudate
155
Which bacteria causes chlamydia?
Chlamydia trachomatis
156
What are the symptoms of chlamydia?
Majority are asymptomatic - if symptomatic, milder than gonorrhoea: Anal discomfort/itch, discharge
157
What is the management of chlamydia?
Azithromycin or Doxycycline (7/7 course)
158
Which STI can present like Crohn's?
Syphilis
159
What are the symptoms of primary syphilis?
Solitary painless ulcer
160
What are the symptoms of secondary syphilis?
• Mucosal patches and ulcers • Eye conditions • Mouth, anogenital, rectal • Condylomata lata • Systemic inflammation (rash on trunk, lymphadenopathy) • Hepatitis
161
How is herpes simplex virus transmitted?
Ano-genital or oro-anal
162
Which area of the lower GI tract is most affected by herpes simplex virus?
peri-anal mucosa but may extend into rectum
163
What are the symptoms of HSV?
Pain, ulcers, painful defaecation, bleeding, mucus, viraemic symptoms (in primary infection)
164
How is human papillomavirus transmitted?
ano-genital, oro-anal
165
Which HSV virus is usually associated with HSC proctitis?
HSV 2
166
Which HPV virus is usually associated with HPC proctitis?
HPV 6, 11, 16, 18
167
What is Lymphogranuloma venereum?
Tropical STI found in Africa
168
What is the treatment for Lymphogranuloma venereum?
Doxycycline
169
What is Lymphogranuloma venereum associated with?
* MSM
* HIV+
* Group sex
* Drug use
* Syphilis
* Hepatitis C
170
How does Lymphogranuloma venereum present?
* Primary (3-30 days):
* Ulcer
* Secondary (3-6/12):
* Inguinal syndrome
* Ano-rectal syndrome
* Tertiary:
* Strictures
* Fistulae
* Genital elephantiasis
171
Why is Gut-Associated Lymphoid Tissue (GALT) particularly susceptible to HIV infection and then replication?
* Often the first point of contact
* Compared with circulating lymphocytes, a greater percentage of these mucosal CD4+ lymphocytes express the CCR5 chemokine co-receptor
* These are the preferred targets for HIV-1
* GI tract in constant state of “physiological inflammation” due to proximity to external environment
* Dense clustering of lymphocytes facilitating cell-cell transmission
172
What are important features to look for in returning travellers with fever?
* Rash
* Hepatosplenomegaly
* Lymphadenopathy
* Insect bites
* Wounds
173
What is acute traveller's diarrhoea?
At least 3 loose stools in 24h, often with self reported fever of multiple possible causes
174
What are 6 main organisms associated with acute travellers diarrhoea?
* Enterotoxigenic E. coli
* Campylobacter
* Salmonella
* Shigella
* Norovirus
* Rotavirus
175
What is the primary investigation for acute traveller's diarrhoea?
Stool culture
176
What medicine can travellers take to stop worsening?
Fluoroquinolone (ciprafloxacin)
177
What are the main forms of enteric fever?
Typhoid/parathyroid fever
178
Which countries are Enteric fevers most associated with?
India and SE Asia
179
Which tropical infections can cause prehepatic jaundice?
* Malaria
* HUS as a complication of E coli
* Sickle cell crisis triggered by infection
180
Which tropical infections can cause hepatic jaundice?
* Hepatitis A and E – acute (occasionally Hepatitis B)
* Leptospirosis
* Malaria
* Enteric fever
* Typhus
* Viral haemorrhagic fever
181
Which tropical infections can cause post-hepatic jaundice?
Ascending cholangitis and helminths
182
Which investigations would you do for fever and jaundice in a traveller?
* Malaria blood film and rapid antigen
* Blood film for red cell fragmentation (HUS)
* FBC/UE/LFT/coagulation
* Blood cultures
* USS abdomen
* Serological testing for viruses
183
What is the incubation period for amoebic liver abscess?
8-20 weeks
184
What are the symptoms of amoebic liver abscesses?
Fever, cough, aching abdominal pain, hepatomegaly, sometimes a history of GI upset (dysentery) – usually male
185
What would you see on CXR with amoebic liver abscess?
Raised right semi-diaphram
186
What is the management for amoebic liver abscesses?
Metronidazole and Paramomycin/diloxanide to clear the lumen of parasites
187
What are helminth infections?
Parasitic worms
188
Which immune cells are helminths associated with?
Eosinophils
189
What are nematodes?
Roundworms
190
What are trematodes and their infection?
Flukes - schistosomiasis
191
What are cestodes?
Tapeworms
192
What is the most common helminthic infection?
Ascariasis - Roundworms
193
What is the life cycle of ascariasis?
1. Egg ingested
2. hatch in small intestine
3. invade gut wall into venous system and via liver and heart reach lungs
4. break into alveoli
5. ascend tracheobroncial tree
6. swallowed and in the gut
7. develop into adult worm where they start to produce eggs.
194
What is the pathophysiology of schistosomiasis?
Adult worms located in portal venules which can lead to hepatolmegaly and liver fibrosis and portal hypertension
195
What kind of exposure can cause schistosomiasis?
Fresh water exposure
196
What organisms cause Chagas' Disease?
Trypanasoma cruzi
197
Aerobes
Organisms that grow better with oxygen, but can also grow without it
198
What are examples of aerobes?
• Staphylococci • Streptococci • Enterococci • Coliforms
199
What are strict aerobes?
Organisms that require oxygen for growth
200
What is an example of strict aerobes?
Pseudomonas sp
201
Which antibiotic are strict aerobes sensitive to?
Gentamycin
202
What are anaerobes?
Organisms that will not grow in the presence of oxygen
203
What are examples of anaerobes?
• Clostridium sp • Bacteroides sp • Anaerobic cocci
204
Which antibiotic are anaerobes sensitive to?
Metronidazole
205
What are coliforms?
Organisms that inhabit the large bowel
206
What are examples of coliforms?
• E coli • Klebsiella sp • Proteus sp • Enterobacter • Serratia sp
207
Which antibiotic are coliform sensitive to?
Gentamycin
208
Which features of the mouth inhibits colonisation?
Mucosal shedding
209
What are the main locations for colonisation in the mouth?
Teeth (Dental plaque → dense biofilms → polymicrobial)
210
Why aren't there commensal bacteria of the stomach and duodenum?
Low pH
211
What are the commensal bacteria of the remaining small intestine?
Coliforms and anaerobes (small numbers due to proximity to stomach)
212
What are commensal bacteria groups of the large intestine?
Anaerobes, coliforms and enterococci
213
What is peritonitis?
Breakdown in the mucosa of GI tract etc can cause leakage of contents which can result in colonisation
214
What is the management for abscesses and why?
Drainage; antibiotics can't be used as large abscesses have poor blood supply so poor antibiotics penetration
215
In general, which antibiotics are for abdominal infections?
AmoxGenMet (if in doubt)
216
Colonisation
The presence of a microbe in the human body that does not cause infection due to a specific inflammatory response
217
sWhat is the pathway of sepsis?
1) Colonisation
2) Infection
3) SIRS
4) Sepsis
5) Severe sepsis
6) Septic shock
218
What is SIRS?
Systemic inflammatory response syndrome.
A non-specific clinical response including at least 2 of the following:
* Temperature \>38oC
* 90 beats/min
* Respiratory rate \>20/min
* White blood cell count \>12,000/mm3 or 10% immature neutrophils
219
Sepsis
The systemic inflammatory response to infection (different from bacteraemia)
Defined as the presence of systemic inflammatory response syndrome (SIRS) with the addition of a confirmed or presumed microbiological infection
220
Severe sepsis
- Defined as sepsis with signs of at least one acute organ dysfunction e.g. renal dysfunction, hypotension
221
Septic shock
Sepsis-induced refractory hypotension that persists despite adequate fluid resuscitation, along with the presence of hypoperfusion abnormalities or organ dysfunction
222
Which areas of the GI tract are usually sterile?
Stomach, duodenum and bile ducts
223
What are the 6 vital steps with sepsis?
O2 FLUID:
Oxygen
Fluids IV
Lactate measurement
Urine output measurement (catheterisation)
Infection screen inc. blood cultures, FBC, CRP +/- urine dip/culture
Drugs – antibiotics as appropriate
224
Which source of infection are you thinking of with contaminated eggs, poultry, meat, unpasteurised milk or juice, cheese?
Salmonella
225
What is the time frame of symptoms with bacillus cereus?
30 mins-6 hrs (vomiting), 6-15hrs (diarrhoea)
226
Which source of infection are you thinking of with dairy products, uncooked and handmade food, e.g. salads and sandwiches?
Staph aureus
227
Which antibiotics is used to treat staph aureus?
Flucloxacillin
228
Which source of infection are you thinking of with beef, poultry, gravy?
Clostridium perfringens
229
Which source of infection are you thinking of with Produce, shellfish, contaminated ready-to-eat food, cruise ship?
Norovirus
230
Which source of infection are you thinking of with children in winter?
Rotavirus
231
Which source of infection are you thinking of with contaminated food or water or contact with animals, travel related ?
Cryptosporidium
232
Which source of infection are you thinking of with trip to SE Asia and change in bowel habit/dry cough?
Enteric fever
233
Which source of infection are you thinking of with o Ova and cysts in hot stool, acute bloody diarrhoea, can cause abscess?
Amoebiasis or giardiasis
234
Mucosa
Aka mucous membrane, membrane that lines various cavities in the body and surrounds internal organs, most of which secrete mucous which stop pathogens and dirt from entering the body and to prevent bodily tissues from becoming dehydrated.
235
True or False: Lymph nodes are concentrationa around sites of mucosal tissue
Tue
236
Which 3 tracts in particular have mucosal tissues?
Respiratory trcat, GI tract and genito-urinary tract
237
Which immune cell predominate in the gut lymphoid tissue?
Memory T cell
238
What are the 2 compartments of the adaptive immune system?
That containing the peripheral lymph nodes and spleen, and then the Mucosal Associated Lymhpoid Tissue (MALT)
239
What are the main components of the GALT for the induction of immune response?
1) Waldeyer's ring (ring of tonsils)
2) Peyers patches of the small intestine
3) Solitary lympohid follicles of large intesitne and rectum
240
What are the important features of the anatomy of the peyers patches?
Dome-like structures extending into the lumen.The overlying layer of follicle-associated epithelium contains microfolds on their surface (instead of microvilli) known as microfold cells or M cells, interspersed between enterocytes. Adapted to direcftly interact with molecules and particules in the gut lumen
241
What happens when the antigens in the lumen meet the M cells?
M cells transport the anigen into the cell by transcytosis and deliver it to antigen presenting cells and lymphocytes (dendtires) of the mucosal immune system. These then release cytokines chemokines which initiate an inflamamtory response
242
What is the function of the solitary lymphoids scattered in the gut wall?
Act as the effector cells
243
What happens when these solitary lymphoid tissues meet antigens?
They activate and move via the lymphatics from the intestines, through mesenteric lymph nodes to thoracic duct to enter blood system and reenter all mucosal lymphoid tissue from there. Therefore the response to the antigen is spread throughout the body.
244
What is MAdCAM-1?
Ligand bound homing receptor (addressin) for gut mucosal tissue
245
What is the dominant antibody isotype for the mucosal immune system?
IgA
246
What are the two distinct compartments of the mucosal immune system?
Epitheliuma and lamina propria
247
Which kind of immune response occurs in the epithelial and lamina propria compartments of the mucosal immune system?
Adaptive and innate response in the lamina propria, and adaptive response in the epithelium
248
What are addressins e.g. MAdCAM-1?
Homing receptors which direct lymphocytes to particular comparments
249
What is oral tolerance?
The feeding of foreign antigens typically leads to a state of specific and active unresponsiveness - tolerance. Although this wouldnt be the case if the same antigens were injected subcutaneosly. Helps maintain the balance between protective immunity and homeostasise
250
What is involved in the innate response of thr mucosal immune system?
* IgA
* Commensal bacteria compete (and win) for nutrients etc)
* Various barriers (mechanical - cilia, tight junctions; chemical - low pH, fatty acids and microbiological- commensals)
251
What are the main mucosal disorders associated with primary immunodeficiency?
* Selective IgA deficiency
* Common Variable Immune Deficiency (CVID)
* X-Linked Agammaglobulinaemia (XLA)
* Chronic Granulomatous Disease (CGD)
* Severe Combined Immune Deficiency (SCID)
252
What organisms are always invovled in Chronic Granulomatous Disease (CGD)?
Staph aureus and asbergillus
253
What kind of reactions are food allergies and what is the pathophysiology?
Type I hypersensitivity reaction initiated by crosslinking of allergen specific IgE on the surface of mast cells with the specific allergen causing degranulation of mast cells in the mucosa
254
Which cells are actually causing the underlying damage in coelic disease?
Immunopathology causing the actual damage is T cell/IEL mediated and their reaction to gluten. Enzyme tissue transglutaminase alters the gluten so that the immune system reacts to it
255
What is the pathophysiology of coeliac disease?
Gamma interferon from Gluten specific T cell activate epithelial cells which produce IL-15 which induces proliferation and activation of IEL. Both T cells and IEL can then kill epithelial cells
256
How do you diagnose coeliac disease?
Serology screening test IgA anti-tissue transglutaminase autoantibodies
257
Which infectious organism would you think of with hazelnut yoghurt?
Clostridium botulinum (bot/pot of yoghurt)
258
Which infectious organism would you think of with soft cheese/coleslaw?
Lesteria monocytgenen (Leicester cheese)
