GI infections Flashcards
1
Q
Gastroenteritis - DEFINITION
A
A rapid onset diarrhoeal illness, lasting LESS THAN < 2 weeks, usually one week, with diarrhoea (loose and unformed stool), 3 or more times a day
2
Q
DEFINITION Diarrhoea
A
- Loose or watery stools passed AT LEAST 3 times in 24 hours which can be acute, chronic or persistent
3
Q
o Acute, persistent, chronic diarrhoea time frames
A
o Acute- lasting < 14 days often due to either viral or bacterial pathogens
o Persistent- between 14-29 days
- entameboa histolytica
- giardia lamblia
- cryptosporidium
o Chronic- lasting > 30 days, may be due to parasites or (often) non-infectious aetiology- IBD/neoplastic causes
4
Q
small bowel vs large bowel diarrhoea
A
-Small bowel diarrhoea:
o Large volume
o Often watery
o crampy abdominal pain with bloating and gas
o RARELY any fever, inflammation, blood, mucus
Large bowel diarrhoea:
oSmall volume
opainful stool
ooften with blood, mucus, inflammatory cells found in the stools
oaccompanying fever
oPatients complain more about blood and mucus than diarrhoea itself
5
Q
main people vulnerable to gastroenteritis
A
infants, elderly, MSM- shigella
Patients with haemochromatosis or haemoglobinopathy
6
Q
secretory vs inflammatory vs enteric fever
A
- Secretory diarrhoea does NOT tend to have a fever or WBCs in the stool- profuse watery diarrhoea
- If there is a fever, it is an inflammatory diarrhoea. with WCC, blood, mucus in stool
- enteric fever: fever but with relatively little/no change in stools- these infections are often more severe.
7
Q
GI infection causes within incubation within 1 day
A
staph aureus bacillius cereus Clostridium perfringens Listeria Norovirus viruses: rotavirus and enteric adenovirus
usually have preformed toxins
8
Q
GI infection causes within incubation after day 1
A
think about enteric fever:
shigella, Campylobacter, salmonella, enterotoxigenic E. coli
9
Q
GI infection causes within incubation after day 4-6 or weeks
A
think about parasites + C.difficile o Cryptosporidium parvum o Giardia o Yersnia ,
10
Q
how does cholera produce profuse diarrhoea
A
toxin production»_space;> - cAMP will open Cl- channels in the apical membrane of enterocytes
leading to Cl- efflux into the lumen and loss of water and electrolytes
They get shock due to fluid loss
11
Q
what type of diarrhoea does cholera produce
A
Cholera is a classic example of secretory diarrhoea
12
Q
how many stool samples needed in parasitic infections
A
In parasitic infections, intermittent shedding occurs so need to send THREE stool samples to see if it can be found
13
Q
which organisms cause Aortitis, Osteomyelitis, deep tissue infection
A
salmonella, Yersinia
14
Q
what organisms cause haemolytic anaemia
A
Campylobacter, Yersinia- this one is longer lasting
15
Q
what organisms cause haemolytic uraemic syndrome
A
**shiga toxin producing E-coli, shigella dysenteriae serotype 1
16
Q
which organisms cause erythema nodosum
A
**Yersinia, **Campylobacter, Salmonella, Shigella
17
Q
which organisms cause Reactive arthritis
A
Salmonella, Shigella, **Campylobacter, Yersinia, rarely Giardia and Cyclospora cayetanensis
18
Q
which organisms can cause Meningitis
A
***Listeria, Salmonella (infants ≤ 3 months of age are at high risk
Viral enteroviruses pathogens can also give meningitis
19
Q
staph aureus- mode of transmission and type of bacteria + treatment + presenting symptoms
A
skin contact, shedding of bacteria from skin when handling food.
prominent VOMITTING, watery non bloody diarrhoea
gram positive, coagulase positive cocci in clusters /tetrads
- Catalase
self limiting: fluid hydration and electrolyte replacement
20
Q
Interleukins produced by staph aureus
A
IL1 and IL2
S. aureus produces an enterotoxin, an exotoxin that can act as a superantigen in the GIT, releasing IL-1 and IL-2.
21
Q
staph aureus appearance on blood agar
A
golden colonies
22
Q
Bacillus cereus - mode of transmission and type of bacteria + treatment + presenting symptoms
A
transmission: reheated fried rice
gram positive rods, spore forming
presenting symptoms: watery non bloody diarrhoea
treatment: self limiting
23
Q
toxins produced by bacillus cereus
A
- Heat stable emetic toxin- not destroyed by reheating
- Heat labile diarrhoeal toxin- when food is not cooked at a high enough temperature (destroyed by heat)
24
Q
complications (2) of bacilllus cereus
A
o cause bacteraemia in vulnerable people
o Can cause cerebral abscesses
25
Clostridia- name the different types
clostridium botulinum, clostridium difficile, clostridium perfringens
26
clostridium botulinum - mode of transmission + treatment + presenting symptoms
transmission: honey (paediatirc/infants) /vaccum packed canned foods
Blocks ACh release from peripheral nerve synapses presenting symptoms: botulinism: paralysis
Treatment: antitoxins + can be inactivated by cooking
27
- Clostridium perfringens - mode of transmission + treatment + presenting symptoms
transmission: reheated meat
(Normal flora of colon but not small bowel, where the enterotoxin acts (superantigen))
presenting symptoms: watery diarrhoea, abdominal cramps, little vomiting lasting 24 hours. Prolonged symptoms may be suggestive of gut infarction and necrosis
Treatment: self limiting but can cause severe disease requiring removal or part of colon
28
Clostridium difficile: type of infection and what does it cause
causes Pseudomembranous colitis
hospital acquired infection
29
toxins produced by C.difficile and significance of this
Toxin A (enterotoxin), Toxin B (cytotoxin)
o Toxin A- causes inflammation of gut with intestinal fluid secretion and damage to the mucosa
o Toxin B- more potent than toxin A, acts as a virulence factor
If PCR +ve but toxin -ve >>> need adequate infection control but may not need treatment depending on if symptomatic or not
30
which group of people are most vulnerable to C.difficile
common in hospitalised patients (30%)
31
what causes C. difficile with specific examples
antibiotic related Collitis (4Cs)
- cephalosporins
- coamoxiclav
- ciprofloxacin
- clindamycin
any of the beta-lactams can be associated with C. difficile too
32
does C.difficile require infection control + prevention
Infection prevention and control precautions are required
o Need to be in a side room with gloves + apron.
o Need to handwash as gel does not kill spores
33
- TREATMENT for C.difficile
o stop antibiotics
o 1st line: PO Metronidazole
o PO Vancomycin
34
what gram staining is clostridium species
gram positive anareobes
35
listeria monocytogenes- gram staining, transmission, presenting symptoms, complications + treatment
listeria: gram positive rods, beta haemolytic, tumbling motility , aesculin +ve
transmission: refrigerated food + unpasteruised dairy
presenting symptoms: GI watery diarrhoea, abdominal cramps, headache, fever, little vomiting
complication: meningitis in elderly and neonates- pregnant woman are very vulnerable
treatment: Amoxicillin
36
Enterobacteriaceae - type of bacteria and characteristics of bacteria
- Facultative anaerobes
- Glucose/ lactose fermenters (LF)
- Oxidase negative
37
one major example of enterobacteracae + transmission, + toxins produced by them + where do they act in the gut + treatment
E-coli: travellers diarrhoea: food/ water contaminated with human faeces
Enterotoxins:
Heat labile- stimulates adenyl cyclase and cAMP
Heat stable- stimulates guanylate cyclase
Acts on the small bowel: jejunum and ileum, but NOT the large bowel, colon
treatment: Should NOT treat with antibiotics
38
types of E-coli
Enterotoxigenic E. coli (ETEC) toxigenic- main cause of traveller’s diarrhoea
Enteropathogenic E. coli (EPEC) pathogenic- infantile diarrhoea
Enteroinvasive E. coli (EIEC) invasive- dysentery-like illness
Enterohaemorrhagic E. coli (EHEC)- also called Shiga-toxin-producing E. coli or STEC
known as E. coli O157:H7 EHEC- the shiga-like verocytotoxin causes Haemolytic Uraemic Syndrome
39
salmonellae - characteristics + colour on agar + antigens + transmission
- Non lactose fermenters- looks clear on plate
- Pale on blood agar
- Antigens- the presence of different combinations of the antigens help to differentiate what subspecies it is. Salmonellae has:
o Cell wall O (groups A-I)
o Flagellar H
o Capsular Vi (virulence antiphagocytic)
transmission: various but can also get this from pet reptiles e.g. turtle, lizard, snake
40
difference between salmonellae and enterbacteriae
- Glucose/ lactose fermenters (LF)- enterobacteriae
| - non lactose fermenters- salmonellla
41
species of salmonella that is of worry
- salmonella typhi + paratyphi
- salmonella enteritidis
- salmonella cholerasuis
42
S. enteritidis- presentation+ transmission + invasion in which part of the bowel + treatment + risk of bacteraemia + investigation
o Transmitted from poultry, eggs, meat
invasion: Invasion of the epi- and subepithelial tissue of the small AND large bowel
presentation: CLASSIC GASTROENTERITIS: Self-limiting non-bloody diarrhoea resolves in 4-7 days with abdominal pain.
o Nausea, vomiting and fever usually resolves in 48-72 hours
treatment: self resolving and no treatment
investigation: stool culture positive
Infrequent bacteraemia rate < 5%
43
S. typhi- presentation+ transmission + treatment + risk of bacteraemia + investigation
transmission: Transmitted ONLY by humans
presentation:
- slow onset
- typhoid enteric fever (no diarrhoea): fever + constipation (after first or second week)
- Extra-intestinal manifestations can occur: splenomegaly, rose spots, anaemia, leukopaenia, aortitis, osteomyelitis (due to peyers patch enlargement)
- Signs: bradycardia, haemorrhage and perforation of the bowel
- Bacteraemia occurs
investigations:
- Blood culture- positive 40-80%
- Stool culture- positive 30-40%
- bone marrow: if negative stool + blood cultures + remains positive until >5 days after antibiotic treatment
TREATMENT: Ceftriaxone
44
Shigellae - characteristics + antigens + classical groups of shigella
non lactose fermenter
non motile
- Antigens:
o Cell wall O antigens
o Polysaccharide (groups A-D):
o Classic groups are:
S. sonnei - Very resistant
S. dyseneteriae
S. flexneri (MSM)
45
why is shigella similar to salmonella + different
-both are Non-lactose fermenters but shigella does not produce hydrogen sulphide like salmonella
46
shigella: presentation+ transmission + carrier state + treatment + investigation + which toxin does it produce
human to human transmission + no carrier state
produces shiga toxin - enterotoxin
presenting symptoms: causes dystentry: diarrhoea with blood and mucus
:Abdominal pain, watery diarrhoea which proceeds to bloody diarrhoea, fever, vomiting
treatment: Disease is SELF-LIMITING to around 7 days: often do NOT recommend antibiotics.
47
difference between salmonella typhi and salmonella entertidis
typhi- 3% are carriers- low compared to S. enteritidis
entertidis: quicker onset and self resolving + transmitted by poultry, eggs, meat
typhi: needs ceftriaxone and entra intestinal manifestations and transmitted only by humans , increased risk of bacteraemia
48
define dystentry
Dysentery (infection of the intestines resulting in severe diarrhoea with the presence of blood and mucus in the faeces)
49
what are the indications for treating shigella with antibiotics
immunosuppressed or if MSM (to prevent onward transmission of the S. flexneri)
50
Vibrios- transmission and specific type of agar plate do you need
characteristical features:
- Handling shellfish, deep sea diver, scuba diving, cutting self on coral
- need specific salty agar plate
characteristics:
- comma shaped
- lactose fermenters
- oxidase positive
51
3 types of vibrio
o Vibrio cholerae - cholera
o Vibro parahaemolyticus
o Vibro vulnificus: cause diarrhoea, seen in septic patients and those with liver disease
52
```
Vibrio cholerae
2 groups
transmission
presentation
colonises which part of the bowel
```
- O1 group: epidemics
- Non O1 group: sporadic or non-pathogens
- Transmission: contamination of water and food from human faeces (shellfish, oysters, shrimp
MASSIVE DIARRHOEA (rice water stool) WITHOUT inflammatory cells
small bowel: secretion of enterotoxin with A and B subunit >>>> constant stimulation of adenylate cyclase
53
Vibrio parahaemolyticus
- transmission
- prevalence in which countries
treatment
RAW or UNDERCOOKED seafood e.g. oysters
- Major cause of diarrhoea in Japan or when cruising in the Caribbean
- SELF-LIMITED for 3 days
54
Vibrio vulnificus
- transmission and what type of hazard causes it
- presenting symptoms + who is vulnerable
- treatmet
- Cellulitis in shellfish handlers
- occupational hazard
- Can cause FATAL SEPTICAEMIA with D+V in HIV/immunosupressed patients
treatment: doxycycline
55
Campylobacter
| characteristics
- Curved, comma or S-shaped
- Microaerophilic- does not require much oxygen to grow
- C. jejuni grows at 42oC
oxidase +ve, MOTILE organism
56
which two organisms are curved comma shaped
vibrio and campylobacter
57
Campylobacter:
transmission
symptoms
treatment
- Transmitted via contaminated food and water with animal faeces (poultry, meat, unpasteurised milk). - Undercooked poultry (chicken at a BBQ)
- Symptoms: watery, foul smelling diarrhoea, bloody stool, fever, severe crampy abdominal pain
- Loose stools occur > 10 x day
treatment: self limiting and lasts for ~ 7 days
- Only treat if immunosuppressed with MACROLIDE
58
when would you treat Campylobacter
- Only treat if immunosuppressed with MACROLIDE
| - TREATMENT: erythromycin or ciprofloxacin if in the first 4-5 days
59
what indicates severe disease in Campylobacter
- Stools may become bloody from 2-3rd day onwards in those with the plasmid PVir which correlates with more SEVERE disease
60
- Extra-intestinal manifestations of Campylobacter
```
o Guillain-Barre syndrome - main one
o Reactive arthritis
o Reiter’s
o Erythema nodosum
o Glomerulonephritis
```
61
- Yersinia entercolitica- characteristic + transmission + presentation
o Non-lactose fermenter
prefers 4oC “cold enrichment
o Transmitted via food contaminated with domestic animals’
Causes:
Enterocolitis
Mesenteric adenitis
62
what conditions is yersnia associated with
**reactive arthritis
**Reiter’s,
Glomerulonephritis,
Haemolytic anaemia
63
which Protozoa causes GI infections
- Entamoeba histolytica
- Giardia lamblia
- Cryptosporidium parvum
64
- Entamoeba histolytica: characteristic features in terms of protozoa
how is it killed
who is at risk of Entamoeba histolytica
o Motile trophozoite in diarrhoea
o Non-motile cyst in non-diarrhoeal illness
o Has 4 nuclei- easy to identify down the microscope
o Killed by boiling, removed by water filters
o More common in MSM
65
presentation of Entamoeba histolytica
classic symptoms
chronic symptoms
flask shaped’ ulcer in ileum
CLASSIC symptoms: dysentery, flatulence, tenesmus
Chronic symptoms: weight loss +/- diarrhoea
liver abscess which requires imaging and further investigations
66
diagnosis of Entamoeba histolytica
Stool microscopy (wet mount, iodine + trichrome)
| Serology in invasive disease
67
treatment of Entamoeba histolytica
TREATMENT: Metronidazole + paromomycin in luminal disease
68
- Giardia lamblia
characteristic features
transmission
symptoms
o Ghost-like trophozoite that is pear-shaped
o Has 2 nuclei + 4 flagellae + suction disk
transmission: faecally contaminated water and food
cruises or resource poor settings
Occurs in travellers, hikers, day care, mental hospitals, MSM
symptoms: No invasion occurs BUT malabsorption of protein and fat lead to symptoms (flatulence, bloating, diarrhoea)
foul-smelling non bloody diarrhoea, cramps, flatulence, NO fever
69
Giardia lamblia- diagnosis
Stool microscopy
ELISA
“String-test”: Swallow a capsule containing some string
70
Giardia lamblia- treatment
o TREATMENT: Metronidazole
71
- Cryptosporidium parvum
who is at risk
and where does it affect
diagnosis:
immunosuppressed
Infects the jejunum
seen in stool by modified Kinyoun acid fast stain
72
- Cryptosporidium parvum- symptoms
o Symptoms: severe diarrhoea in the IMMUNOCOMPROMISED (e.g. HIV
73
which stain is used for Cryptosporidium parvum-
in stool by modified Kinyoun acid fast stain
74
o TREATMENT for Cryptosporidium parvum-
Self-limiting so no other treatment
| Reconstitution of the immune system
75
common cause of gastroenteritis outbreaks in hospitals
Norovirus
76
do you get long term immunity with norovirus
- NO long-term immunity – once you’ve had it, can get it again
77
how can you remove norovirus
it is very resistant to cleaning
78
what is the infectious disease criteria/ dose of norovirus
very LOW infectious disease criteria/ dose
79
viruses that cause GI infections and which population do they infect
- norovirus- common outbreaks in hospital
- adenovirus: immunocompromised and non bloody diarrhoea <2. years of age
- rotavirus: children aged 6 months to 2 years but can affect the elderly
others:
- Poliovirus
- Enteroviruses (coxsackie, ECHO) - meningitis esp in neonates
- Hepatitis A
80
- Rotavirus
o children aged 6 months to 2 years but can affect the elderly
o occasionally cause diarrhoea in the elderly
SYMPTOMS: secretory diarrhoea, NO inflammation
81
do you get lifelong immunity in rotavirus
o Exposure to natural infection TWICE confers lifelong immunity
82
adenovirus - who does it affect
Types 40 and 41 cause non-bloody diarrhoea < 2 years of age
Any type in immunocompromised
83
diagnosis of adenovirus
o Diagnosis:
Stool electron microscopy
Antigen detection
PCR
84
MOST IMPORTANT Infection Prevention and Control
o Good handwashing
85
how should D+ V be managed in hospital
- In hospital- D+V should be isolated
86
vaccines
- Cholera- INACTIVATED
- Campylobacter
- ETEC - in trial
- Salmonella typhi- live vaccine
- Rotavirus- given to children: Age of vaccine is 6-12 weeks can be offered this
87
public health notifiable diseases
```
o Campylobacter
o Clostridium sp.
o Listeria monocytogenes
o Vibrio
o Yersinia
o Salmonella
```
-
88
Which virus is commonly associated with outbreaks?
- Norovirus
