Microbiology 6 - GI infections Flashcards
1
Q
In a febrile patient with a GI infection, what are the key differentials?
A
- Inflammatory diarroea
- If no diarrhoea - enteric fever (typhoid/ salmonella)
2
Q
In an afebrile patient with a GI infection, what is the top differential?
A
Secretory diarrhoea due to toxins (eg cholera)
3
Q
What is the incubation period of campylobacter?
A
1-10 days
4
Q
What is the incubation period of bacilus cereus?
A
1-6 hours
5
Q
Why does staph aureus food poisoning produce such rapid symptoms?
A
Toxin is pre-formed
6
Q
What are the key cytokines involved in Staph aureus food poisoning?
A
IL-7 and IL-2
7
Q
Describe the symptoms of S aureus food poisoning
A
Vomiting
Waterey, non-bloody diarrhoea
8
Q
Describe the different toxins produced by bacilus cereus
A
Heat-stable toxin causes emesis
Heat-labile toxin causes diarrhoea
Only the heat-labile toxin is destroyed upon heating
9
Q
Describe the diarrhoea produced by bacilus cereus
A
Waterey, non-bloody
**after reheating rice/chinese takeout*
10
Q
In what type of food might clostridia botulinum be found?
A
Honey
and vacuum packed foods
11
Q
What type of clostridia spp causes food poisoning?
A
Clostridia perfringens
12
Q
In what sort of food is clostridia perfringens found?
A
Re-heated meat
13
Q
Which organism causes pseudomembranous colitis?
A
Clostridium difficile
14
Q
Which diarrhoeal disease is associated with antibiotic use?
A
Pseudomembranous colitis caused by C. difficile
15
Q
What type of symptoms does listeria monocytogenes poisoning cause?
A
Febrile gastroenteritis
Waterey diarrhoea
16
Q
Recall 2 sources of listeria poisoning
A
Unpasteurised dairy Refringerated foods (eg sandwiches)
17
Q
Is listeria alpha or beta haemolytic?
A
Beta haemolytic
18
Q
What is the causative organism in ‘traveller’s diarrhoea’?
A
Enterobacteriacae (usually the toxogenic form, ETEC)
enterotoxogenic escherchia coli
escherichia coli
19
Q
What organism causes haemolytic uraemic syndrome?
A
EHEC enterobacteriacae
20
Q
Recall one very important thing to avoid in the management of enterobacteriacae poisoning
A
Antibiotics
21
Q
Recall 3 worrying species of salmonella
A
S typhi
S enteritidis
S cholerasuis
22
Q
What symptoms are caused by S typhi infection?
A
Bactaraemia
Constipation and fever
Splenomegaly and ROSE SPOTS
23
Q
What are the 2 key forms of shigella that cause disease in humans?
A
S dysenteriae S flexneri (associated with MSM)
24
Q
What disease pattern does shigella infection cause?
A
Dysentry
25
How should shigella infection be managed?
Avoid antibiotics
If really necessary, go for ciprofloxacin
26
What is the typical stool appearance in Vibrio cholerae infection?
Rice water
27
Which organism is most likely to cause cellulitis in a scuba diver/shellfish handler?
Vibrio vulnificus
28
On what sort of agar can vibrio spp be grown?
Salty agar
\*\*vibrio, shellfish, salty
29
For how long can campylobacter symptoms last?
Up to 20 days
30
What is one key serious complication of campylobacter infection?
Guillan Barre syndrome
31
What is the symptom of "flask-shaped ulcer" pathognemonic for?
Entamoeba histolytica infection
32
What symptoms does E. histolytica infection cause?
Dysentry and flatulence
33
How should E. histolytica infection be managed?
Metronidazole
34
How can giardia infection be investigated?
String test
35
How should giardia infection be treated?
Metronidazole
36
In which patient group does cryptosporum parvum cause symptoms, and what are those symptoms?
The immunocompromised
Severe diarrhoea
37
Recall the 1st and 2nd line treatments for clostridium difficile
1. Metronidazole
2. Vancomycin
38
Definition of diarrhoea
Loose or watery stools at least 3 times a day.
Can be acute, persistent or chronic
a) acute: \< 2 weeks
b) persistent: between 14-30 days
c) chronic: over 1 month
39
Small bowel vs large bowel diarrhoea
Small bowel:
* often large volumes
* often very watery, with gas and bloating
* often no accompanying fever
* no blood, mucous or inflammatory cells
Large bowel
* small volumes
* not watery. often accompanied with PAIN
* often with accompanying fever
* often has blood, mucous or inflammatory cells
40
secretory diarrhoe vs enteric fever vs inflammatory diarrhoea?
_Secretory diarrhoea-_ due to toxin production
* Change in stools- profuse watery diarrhoea
* No fever
* No WBC in stool
\*\*basc just irritation to GI tract; not very unwell\*\*
_Inflammatory diarrhoea_
* Change in stools
* Fever present
* WBC in stool
\*\*bacteria trying to actually invade the GI tract; unwell and lots of GI symptoms\*\*
_Enteric fever_
* No change in stools
* Fever present
* WBC in stool present
\*\*unwell but no GI symptoms\*\*
41
Which organisms cause persistent or chornic diarrhoea?
1. entameboa histolytica
2. giardia lamblia
3. cryptosporidium
42
Which organisms cause dysentry?
**CHESSY**
Campylobacter
Haemorrhagic E. Coli
Entamoeba histolytica (parasite)
Salmonella
Shigella
Yersinia enterocolitica
43
Which bacteria causes swinging fevers?
E. Histolytica
44
Which organisms cause abdominal pain?
E.Coli O157
Salmonella
Shigella
Campylobacter
Yersinia
noncholera Vibrio species
Clostridium difficile
45
Which organism causes persistent abdominal pain and fever?
Yersinia Enterocolitica
46
Which organisms cause nausea and vomiting lasting less than 24 hours?
These are the short incubation emetic syndromes.
1. B Cereus
2. Toxins of Staph Aureus
47
Typical Sx of clostridium perfringens
Abdominal cramps and watery diarrhoea
(non bloody)
48
Typical symptoms of Staph Aureus Gastroenteritis
Vomiting\>diarrhoea
can cause systemic toxicity - tachycardia and hypotension
49
Typical symptoms of B cereus Gastroenteritis
Vomiting first
Followed by diarrhoea after 6 hours
\*non bloody diarrhoea
50
Typical symptoms of cholera infection
Rice water stools
Severe watery diarrhoea
Sometimes afebrile
51
Symptoms of salmonella
Bloody diarrhoea (sometimes)
52
Symptoms of E Coli
Traveller's diarrhoea: non-bloody
Bloody diarrhoea: haemorrhagic E. Coli
53
Symptoms of Shigella
Bloody diarrhoea
More common in MSMs
54
Symptoms of camylobacter
Bloody diarrhoea
Prodromal illness
55
Symptoms of giardia lamblia
bloating
flatulence
chronic diarrhoea
non-bloody diarrhoea
malabsorption
56
Symptoms of entameboa histolytica
Bloody diarrhoea
Liver/lung/brain abscesses
Swinging fevers
Flask shaped ulcers in the intestine
Flatulence
Tenesmus
57
Which organism causes vomiting and non-bloody diarrhoea for 1-2 days?
Norovirus
58
Which organisms cause long incubation emetic syndromes?
B cereus
C perfringens
Diarrhoea+adominal cramping 1-2 days
59
Which organisms cause Aortitis, Osteomyelitis, deep tissue infection (2):
salmonella
Yersinia
60
Which organism cause haemolytic anaemia?
Camylobacter
Yersinia
61
Which organisms cause gloerulonephritis?
Shigella
Campylobacter
Yersinia
62
Which organisms cause HUS?
STEC- shiga toxin producing E Coli
63
which organisms cause Erythema nodosum (4):
Yersinia
Campylobacter
Salmonella
Shigella
64
Which organisms cause reactive arthirtis
Salmonella
Shigella
Campylobacter
Yersinia
65
WHich organism cause meningtis?
LIsteria and salmonella
More at risk in young babies
66
Characteristics of B cereus
67
how does b cereus transmit?
reheating rice causes spore germination
68
WHat type of organism is staph auerus?
69
Transmission of staph auerus
Spread from skin of food handlers
causing food poisoning
70
Gram stain of clostridium species
Gram positive anaerobes
71
Clostridium botulinism
72
Clostridium perfringens
* Source : reheated food (meat)
* Normal flora of **colon** but not small bowel, where the enterotoxin acts (superantigen)
* Incubation 8-16hrs
* Watery diarrhoea, cramps,little vomiting lasting 24hrs
73
Clostridium difficile
* ¡It is not an invasive disease and non-toxin producing strains do not often cause disease but can colonise the gut and asymptomatic shedders of spores can continue to act as a reservoir for infection
* C.difficle produces two toxins; Toxin A, an enterotoxin and Toxin B, a cytotoxin
* Toxin A causes inflammation with intestinal fluid secretion and damage to the mucosa
* Toxin B, more potent than toxin A acts as a virulence factor
* HAI
* Antibiotic related colitis
74
Which antibiotics cause C difficile colitis
Cephalosporins
Clindamycin
Ciproflocaxin
Co-amoxiclav
75
Which toxin of C. Difficile is entertoxic?
Toxin A
| (Toxin B is the virulence factor)
76
Management of C difficle colitis
Stop antibiotics
PO metronidazole
If doesn't work--\> Vancomycin
77
Characteristics of vibrio bacteria
Gram negative **(V for VIOLENT)**
Comma shaped
Late lactose fermenters
Oxidase positive
78
Gram stain of vibrio cholerae
Gram negative anaerobe
- comma shaped
- late lactose fermenter
- oxidase positive
GRAM NEGATIVE ROD
79
Transmission of vibrio cholerae
Faeco-oral
Faecally contaminated water- eg shellfish, shrimp etc
80
Pathophysiology of diarrhoea caused by Vibrio cholerae
Produce toxins A and B- bOTH ARE ENTERTOXINS
They cause chloride channel opening - loss of chloride ions into the intestine--\> water follows
MASSIVE watery diarrhoea (rice water stools)
81
What type of organism is Listeria?
Gram positive
Facultative intracellular rod bacteria
B Haemolytic
Ausculin positive
Tumbling motility
82
How is listeria transmitted?
Listeria grows in refrigerated foods - unpasteurised milk, vegetables,
83
Symptoms of listeria monocytogenes
GI watery diarrhoea
cramps
headache
fever
little vomiting
84
Treatment of listeria
Amoxicillin and gentamicin
85
What are the Enterobacteriaceae?
E Coli
Salmonella
Shigella
Klebsiella
Yersinia
86
CHaracteristics of enterobacteraciea?
Gram negative
Facultative anaerobes
Glucose/ lactose fermenters (LF)
Oxidase negative
87
4 types of E. Coli
1. ETEC: enterotoxiogenic
2. EPEC: enteropathogenic
3. EIEC: enteroinvasive E. Coli
4. EHEC: enterohaemorrhagic E. Coli
88
ETEC
toxigenic
main cause of traveller’s diarrhoea
89
EPEC
pathogenic
infantile (paediatric) diarrhoea
90
EIEC
invasive
dysentery-like illness
91
EHEC
also called Shiga-toxin-producing E. coli or STEC
Often people know this as E. coli O157:H7 EHEC
shiga-like verocytotoxin → HUS
\*\*May present with diarrhoea + bruising (suggesting thrombocytopaniea)
92
How do you treat E. Coli diarrhoea?
Self-limiting
avoid antibiotics
if really necessary then ciprofloxacin
93
Salmonella features
* Non lactose fermenters,
* H2S producers, TSI agar,
* XLD agar,selenite F broth
gram negative bacili
* Facultative anaerobes
* Lactose fermenters
* Oxidase-negative
94
Antigens produced by salmonella
- cell wall O (groups A-I)
- flagellar H
- capsular Vi (virulence, antiphagocytic)
95
Main species of Salmonella
1. S. typhi (and paratyphi) - causes enteric fever
2. S.enteritidis - causes dysentry
96
Presentation of salmonella typhi
1. Slow onset- symptoms occur after 1st or 2nd week
* Fever and constipation
* DON'T HAVE DIARRHOEA
2. Extra-intestinal manifestations (4):
* splenomegaly
* rose spots
* anaemia
* leukopaenia
3. Signs (3):
* bradycardia
* haemorrhage
* perforation of the bowel
97
Treatment of salmonella typhi
IV Ceftriaxone --\> PO azithromycin
98
Presentation of salmonella enteriditis
99
Tx of salmonella enteriditis
Causes classic enteroclitis
Treatment is usually self-limiting
**Path guide: can treat with ceftriaxone if required**
**Pathsoc: cipro**
**\*\*learn cipro**
100
Characteristics of shigella
gram negative bacillus (like the other enteroBacter)
101
Presentation of shigella
102
Treatment of shigella
Self-lmiting
May require ciprofloxacin if immunosuppressed or MSM (risk of Shigella flexneri which is dangerous)
103
Camypylobacter characteristcs
* Gram-negative ROD
* Comma-shaped
* Microaerophilic
* Oxidase-positive
* Motile
camping is AWFUL - NEGATIVE
104
Campylobacter transmission
* faecal-oral transmission
* contaminated food and water with animal faeces
* Associated with BBQs
105
Presentation of campylobacter
* watery, foul smelling diarrhoea:
* Loose stools occur \> 10 x day
* fever
* bloody stool:
* Stools may become bloody from 2-3rd day onwards
* in those with the plasmid PVir which correlates with more SEVERE disease
* severe crampy abdominal pain
106
Tx of campylobacter
Self limiting
Treat with cipro or erythromycin if immunocompromised
\*\*acc to passmed, clarithromycin is first line. but check...\*\*
107
Yersinia enteroclitica characteristcs
example of enterobacter hence:
Gram-negative, bacillus
108
Testing for Gastroenteritis
Stool samples
a) culture dependent: microscopy
b) culture independent: PCR
109
Why do you need 3 stool samples for parasitic infections?
Intermittent shedding of ova
110
Antibiotics for GI infections
111
E. histolytica characteristics
112
Aetiology of E. Histolytica
113
Presentation of E. histolytica
114
Giardia lamblia: microscopic features
* trophozoite “pear shaped”
* 2 nuclei
* 4 flagellas and a suction disk
* Ingestion of cyst from fecally contaminated water,food
115
Giardia Lamblia
* Travellers, hikers, day care, mental hospitals, MSM
* foul smelling non bloody diarrhoea, cramps
* flatulence, no fever
* Diagnosis : stool micro, ELISA, “string test”
* Treatment :metronidazole
116
Example of protozoan diarrhoea
Cryptosporidium parvum
117
Characteristics of cryptosporidium
* Infects the jejunum
* Severe diarrhoea in the immunocomromised
* Oocysts seen in stool by modified Kinyoun acid fast stain
* Treatment : reconstitution of immune system
118
Norovirus diarrhoeal illness
* Outbreaks
* Low ID (18-1000 viral particles)
* Environmental resilience (0-60 ºC)
* No long term immunity
* GII.4 currently predominant strain
119
Rotavirus diarrhoea
* dsRNA “wheel like”
* Mean duration of symptoms for 3-8 days
* Population: occurs in children aged 6 months to two years + occasionally in the elderly
* When: Often year round in tropical climates and in the winter months in temperate areas
* Presentation:
* Vomiting is less of a prominent feature than in norovirus although it can be difficult to distinguish between them
* Replicates in mucosa of small intestine
* Secretory diarrhoea, no inflammation
* Watery diarrhoea by stimulation of enteric nervous system
120
Can you be immune to rotavirus?
Yes
* By age 6 most children worldwide have antibodies to at least one type¡
* Exposure to natural infection twice confers lifelong immunity
121
Adenovirus diarrhoea
* can affect \<2yo and elderly
* non-bloody diarrhoea
122
Examples of vaccines against GI bacteria
Cholera
Salmonella Typhi
Rotavirus
123
Notifiable organisms
Campylobacter
Clostridium sp.
Listeria monocytogenes
Vibrio
Yersinia
124
Definition of gastroenteirtis: duration
\>2 weeks of symptoms
125
Which extra intestinal manifestation is comonest with S. Typhi?
Aortitis
126
Complications of campylobacter
GBS- guillan barre syndrome- tingling
Reiter's syndrome: can't see, can't pee, can't climb a tree
127
Treatment of parasitic infections
Generally metronidazole
128
Crampy adbominal pain + diarrhoea (bloody or non-bloody)
Campylobacter
129
Treatment for c. jejuni?
Erythromycin or cipro if in first 5 days
130
Summary of gram stains of organisms and buzz words
131
Which organisms cause secretory diarrhoea?
Cholera, ETEC, EPEC, viruses
| (also Staph aureus- toxins A and B)
132
Which organisms cause inflammatory diarrhoea?
Campylobacter jejuni, Shigella, non-typhoidal Salmonella, EIEC
133
Which organisms cause enteric fever?
Typohoidal salmonella, Yersinia, Brucella
134
C. botulinim paralysis vs GBS paralysis
Botulinum- descending paralysis
GBS- ascending paralysis
135
Reheated meats, 8-16hrs incubation
Watery diarrhoea + cramps, lasts 24hrs.
Also causes gas-gangrene
C. perfringens
136
B. cereus treatment
Self-limitimg
137
What type of diarrhoea does B. cereus cause?
Watery non-bloody diarrhoea
138
Two forms of B. cereus
a) short incubation - sudden vomiting --\> non-bloody watery diarrhoea
b) long incubation --\> watery non-bloody diarrhoea
\*\*basc short incubation has vomiting but long incubation has no vomiting\*\*
139
Staph aureus presentation
Short incubation
Prominent vomiting, watery diarrhoea
140
Tx of staph aureus diarrhoea
Self-limiting
141
Which vibrio species is transmitetd through raw seafood and is common in Japan?
Parahaemolyticus
142
Treatment of vibrio diarrhoea
Self-limiting
143
Which are the only bacterial causes of diarrhoea you need to treat with antibiotics?
**1. C difficile** - metronidazole --\> vanocmycin
2**. Enterobactericiae**- ceftriaxone (salmonella) or ciprofloxacin (e coli, shigella)
ESS- cipro, ceftriaxone (typhi), cipro (enteritidis)
**3. C jejuni**- erythromycin or cipro if within 5 days (\*\*acc to quesmed- there is a lot of resistance to cipro which is why you give erythromycin)
**4. Listeria**- ampicillin
144
C jejuni description
* Comma-shaped
* Microaerophilic
* Oxidase-positive
* Gram-negative
* Motile
gram negative rod
\*\*because when you go camping you light fire using logs/rods\*\*
145
146
Tx of cryptosporidium parvum
paromomycin
147
3 main viral causes of diarrhoea
Norovirus
Adenovirus
Rotavirus
**(NAR)**
--\>all cause secretory diarrhoea which is self-limiting
norovirus in adults; adenovirus and rotavirus in children.
148
Diarrhoea and vomiting after raw eggs
salmonella enterica
149
Summary of key incubation periods to know
1-6 hrs: Staphylococcus aureus, Bacillus cereus\*
12-48 hrs: Salmonella, Escherichia coli
48-72 hrs: Shigella, Campylobacter
\> 7 days: Giardiasis, Amoebiasis
150
host related risk factors for developing GI infections
* Young children and elderly
* Less seen in infancy but can see some
* **Immunosuppressed** patients
* **_Men who have sex with men (MSM) – shigella_**
* Anal-genital, oral-anal, or digital-anal contact
* Patients with **haemochromatosis** or **haemoglobinopathy**
151
incidences of bacterial vs viral Gastroenteritis
incidence of bacterial gastroenteritis is far less than viral gastroenteritis
152
Bacillus cereus: complications:
* _cause bacteraemia_ in vulnerable people
* Can cause **cerebral abscesses**
153
list some organisms with incubation period of within 1 day
* staphylococcus
* *clostridium perfringens*
* norovirus
* viruses (Rotavirus, enteric adenovirus)
* *listeria monocytogenes*
* *bacillus cereus*
they typically have preformed toxins
154
list some organisms with incubation period after day 1
enteric pathogens
* *Salmonella, shigella, campylobacter,* enterotoxigenic *E. coli*
* \*\*so basically the bacteria as part of CHESSY (except ETEC not EHEC)\*\**
155
list some infections with incubation period up to 4-6 days after or weeks
* Think about **parasites + C.difficile**
cryptosporidium parvum
Giardia
Yersnia
156
key differences between enteric fever and inflammatory diarrhoea
inflammatory diarrhoea = exudative diarrhoea
enteric fever = interstitial inflammation
157
how many stool samples need to be sent in parasitic infections
* In parasitic infections, intermittent shedding occurs so need to send _THREE_ stool samples to see if it can be found
158
Giardiasis vs ameobiasis: bloody vs non bloody?
Giardiasis: tends to be non bloody
Ameobaisis: tends to be bloody
159
WHich organism causes diarrheoa and flu like illness?? \*\* confirm
Campylobacter
