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Year 2 clinical pathology > week 6 Gastroenteritis and intra abdominal infections > Flashcards

week 6 Gastroenteritis and intra abdominal infections Flashcards

1
Q

Are the bacteria of the commensal flora aerobic or anerobic?

A

Obligate anaerobic bacteria–> can’t survive in the presence of oxygen

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2
Q

The faecal flora ahs been estimated to have a metabolic capactiy equal to what organ?

A

The liver

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3
Q

What are the beneficial effects of commensal flora of the gut?

A

Metabolism,

Colonisation resistance Antibody induction

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4
Q

What might have a profound effect on the composition of gut flora?

A

Diet

Early years exposure –> bottle fed vs breast fed babies

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5
Q

What vitamins are secreted by the bacteria in the gut?

A

Vitamin K and B12

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6
Q

Everyone has different flora compisiton in there gut due to different exposure. What is the affect of bottle fed and breast fed on the gut flora?

A

Bottle fed –> adult microflora

Breast fed babies –> bifidobacteria

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7
Q

When does colonisation of the gut begin?

A

You are born sterile and colonisation begins at birth

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8
Q

what is the second leading cuase of death in children under 5 years old?

A

Diarrohea

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9
Q

What are the common bacterial causes of gastroenteritis? (8)

A

Salmonella,

- Shigella, 
- E coli
- Campylobacter 
- Vibrio cholerae 
- Clostridium difficile
- Staph aureus
- Bacillus cereus
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10
Q

What parasitic causes of gastroenteritis?

A

Entamoeba hist.

- Giardia lamblia
- Cryptosporidium
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11
Q

What virus causes gastroenteritis?

A

Norovirus

- Rotavirus

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12
Q

what are the presenting complaints of gastroenteritis?

A 
Acute onset
Vomiting and/or
Diarrhoea – frequency, mucous, blood
Abdominal pain
Systemic effects – fever etc.
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13
Q

what complications can you get with gastroenteritis?

A 
Dehydration	
Renal failure	
HUS
Toxic megacolon	GBS		
Salmonella
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14
Q

What are the investigations for gastroenteritis?

A

Bloods – FBC, U&E, CRP, blood cultures
Abdominal Xray – if severe
Stool

Looking for markers of infection –> detecting bodies reponses

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15
Q

What is the difficulty of investigating the cause of gastroenteritis?

A

There is so many different organisms in the gut that it is difficult from differentiating between the good and bad organisms.

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16
Q

What tests are done on stools in the analysis of the cause of gastroenteritis?

A

Ova, parasites and cysts ‘OCP’
Microscopy, culture and sensitivity ‘MC&;S’
Clostridium difficile toxin ‘CDT’
Viral PCR

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17
Q

What is the most common cause of gut infection?

A

Norovirus

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18
Q

What type of virus is norovirus?

A

Either Norwalk-like virus, SRSV (small round structured virus
Winter-vomiting disease

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19
Q

What are the main symptoms of norovirus?

A

Diarrhoea and projectile vomiting

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20
Q

How long does norovirus infection last and what is the management/treatment?

A

Illness last for 24-48hrs.

No specific treatment just allow the the infection to run its course –> lots of water to prevent dehydration

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21
Q

What is the advice given for people who have been infected by norovirus?

A

Stay away from work to prevent spreading the disease to other people, and practice good hygiene and handwashing to prevent spread to others.

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22
Q

What vacine has been introduce for children to prevent norovirus infection?

A

Rotavirus vacine

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23
Q

How does the norovirus spread?

A

Aerosols –> vomiting, feacal/oral route –> particules

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24
Q

What type of disease is cryptosporidosis? What does it contaminate?

A

Waterborne disease

Contaminated drinking water, swimming pools, water features, natural waters, animal and human contact, other routes

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25
Q

How can cryptosporidum infection harbour in swimming pools?

A

Oocyst resistance to chlorine based disinfectants

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26
Q

Why is salad bags a source of contaimnation for cryptosporidiosis?

A

Washing the salads with contaminated water

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27
Q

What are the two modes of action of bacteria causing gastroenteritis?

A

Enterotoxin –> the production of toxins that cause the disease

Adherance –> the bacteria it self causes the infection

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28
Q

Give example of enterotxin bacteria that cause gastroenteritis? (6)

A 
Vibrio cholerae
Escherichia coil 
Clostridium perfringens
Staphylococcus aureus
Bacillus cereus
Clostridium difficile
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29
Q

Give 4 examples of adherance bacteria that causes gastroenteritis?

A

Shigella sonnei / flexneri
Escherichia coil
Campylobacter jejuni
Salmonellae

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30
Q

Other than GI disease what other diseases can E.coli cause?

A

UTI

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31
Q

What is the major source of E.coli 0157?

A

Cattle

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32
Q

What type of toxin is produce by E.coli 0157?

A

Shiga toxin virulence

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33
Q

In what percentage of people who have E.coli 0157 will develop haemolytic uraemic syndrome?

A

10-15%

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34
Q

What is haemolytic uraemic syndrome?

A

The toxin doesn’t just affect the epithelial cells but also the RBc–>

Toxin causes premature destruction of the red blood cells which then clog the body’s filtering system, the kidneys, causing hemolytic-uremic syndrome (HUS).

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35
Q

How does E.coli cause diarrohea?

A

Toxin act on epithelial cells and cause massive activation of ion channels.
This causes huge amount of ions to be released from the gut lumen and therefore the lumen becomes really salty –> body tries to fix this but by diliuting the salty liquid causes diarrohea

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36
Q

Is salmonella a enterotoxin or adherance bacteria?

A

Adherance bacteria

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37
Q

What disease does salmonella cause? (3)

A

Typhoid –> Can spread outside of the GI tract and

Paratypoid strains stick in the GI tract only

Food poisining

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38
Q

What is the general treatment of gastroenteritis?

A

Supportive management
Generally avoid antibiotics
May increase duration of salmonella carriage
May worsen E. coli HUS

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39
Q

What are the different strains of salmonella?

A

S. typhi
S. paratyphi
S. enteritidis
S. typhimurium

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40
Q

When do you give antibiotics to treat gastroenteritis?

A

in very young & very old
Campylobacter – prolonged or severe symptoms
Invasion (e.g. positive blood cultures)

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41
Q

Why should you not give antibiotics to treat infection caused by bacteria that release toxins?

A

By killing the bacteria you will cause toxin to be released which will make it even worse

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42
Q

What percentage of patients will get antibiotic associated diarrohoea?

A

5-30%

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43
Q

What affect does antibiotics have on gut microflora ?

A

Change in metabolism (change levels of carbohydrates / bile acids) of what is happening in the gut

Overgrowth of pathogenic organisms

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44
Q

What organisms cause antibiotic assoicated diarrohoea?

A 
Clostridium difficile  --> accounts fo 10-25% 
C. perfringens, 
S, aureas,
 Candida spp, 
Klebsiella spp, Salmonella spp
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45
Q

What is the symtpoms of AAD?

A

Symptoms range from mild diarrhoea to pseudomembranous colitis
- Can lead to Toxic megacolon, perforation, shock

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46
Q

What is the main cause of pseudomembranous colitis?

A

C.difficile

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47
Q

What strain of C.difficile cause death in the young?

A

Non-NAP1

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48
Q

What antibiotics pose a high risk of C.difficile infection?

A

cephalosporins

clindamycin

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49
Q

What antibiotics pose a medium risk of C.difficile infection?

A

ampicillin/amoxycillin
co-trimoxazole
macrolides
fluoroquinolones*

50
Q

What antibiotics pose a low risk of C.difficile infection?

A 
aminoglycosides
metronidazole
anti-pseudomonal 	penicillins +             	b-	lactamase inhibitor
Tetracyclines
rifampicin
vancomycin
51
Q

What are the control measures for C.difficile infection?

A

Early warning system to identify changes in local epidemiology
Reduce risk of transmission
Early isolation/cohorting of patients with diarrhoea
Environmental cleaning, chlorine
Hand hygiene soap & water
Examine/optimise/reduce overall antibiotic use
Limit high risk agents in high risk patients
Feedback CDI & antibiotic data on a regular basis

52
Q

What is the current treatment of C.difficile infection?

A

oral metronidazole / oral vancomycin

New treatment –>
NEW – oral fidaxomicin –> V. expensive but good

53
Q

What is alternative way of treating C.diff rather than giving antibiotics?

A

Faecal transplant

54
Q

what is the definition of intra-abdominal infection?

A

Presence of micro-organim in a normally-sterile site within the abdominal cavity.

Sterile sites
Peritoneal cavity
Hepatobillary trea

55
Q

Why is gastroenteritis not a example of intra-abdominal infection?

A

Because the bowel lumen is not a sterile site

56
Q

What part of the GI tract below the oesophagus is suppose to be sterile?

A

The stomach and the proximal small intestine.
Due to the production of the bile which inhibits growth.

The distal intestinal flora reflects that of large intestine and is not sterile

57
Q

What organisms are found in the proximal part of the small intestine?

A

A few aerobic bacteria and Caninda spp (yeast)

58
Q

What type of flora is there in the distal part of the small intestine?

A

Very similar to the large intestine

59
Q

What does large intestine mainly contain?

A

95-99% of the large intestine is made up of anaerobic bacteria –> don’t offer encounter in infection

60
Q

What aerboic baceteria are fonnd in the large intestine?

A

Enterobacteriaceae (enteric Gram-negative bacilli, coliforms)

Gram-positive cocci (mainly enterococci)

61
Q

What are the sources of intra-abdominal infection?

A

Gastrointestinal content

Blood

External

62
Q

What are the 3 different mechanisms of intra abdominal infection?

A

Translocation of micro-organisms from inside the lumen of the GI tract to outside the peritoneal cavity.

Translocation of microorganism along a lumen

Translocation of microorganims from extra-intestinal source

63
Q

What are the different types of translocation across a wall? Give example of each

A

Perforation–> most common
Perforated appendix, perforated diverticulum, bowel cancer and perforated ulcer.

Loss of integrity –> ischemia due to blood vessel being blocked that leeds to stragulation then hernation and this caues leakage to the peritoneal cavity.

Surgery –> seeding at operation or anastomeses leak.

64
Q

What are the different types of translocation along a lumen?

A

Blockage
Cholecystitis, cholangitis, hepatic abscess

Iatrogenic
Instrumentation (e.g. ERCP)

65
Q

Who are most likely to get a perforated appendix?

A

Disease mainly of children and young adults

66
Q

What is the symptom of perforated appendix?

A

Severe and generalised pain

67
Q

What can be a consequence of perforated appenix?

A

Shock

68
Q

What might perforated appendix form?

A

Form appendix mass.

Which is Inflamed appendix with adherent covering of omentum and small bowel.

69
Q

What happens during perforated appendix?

A

Obstruction of lumen of the appendix. Caused by

1) Lymphoid hyperplasia or faecal obstruction
2) Results in stagnation of luminal contents, bacterial growth and recruitment of inflammatory cells
3) Build up of intraluminal pressure may result in perforation
4) Escape of luminal contents into peritoneal cavity is “peritonitis”

70
Q

What is the treatment for perforated appendix?

A

Surgery: appendicectomy

Antibiotics: cefuroxime & metronidazole for 5 days

71
Q

What is a diverticulum/

A

Hernation of mucosa/submucosa through muscular layer.

Occurs in the sigmoid and descending colon.

72
Q

How common is asymptomatic diverticulum and to who’m does it occur in?

A

50% over 70yrs

73
Q

What are the complications of diverticulum?

A

Diverticulitis
Perforation
Pericolic abscess

74
Q

What complication may be caused by bowel cancer?

A

Intraperitoneal and/or bloodstream infection is an infrequent complication

75
Q

What blood stream infections occur in a person with bowel cancer?

A

Especially associated with Clostridium septicum and Streptococcus gallolyticus (formerly S. bovis) bloodstream infection

76
Q

What is the thought of the cause of intra-abdominal infection for a person with bowel cancer?

A

Presumably caused by loss of bowel wall integrity due to abnormal malignant tissue

77
Q

What symptoms would a bowel cancer patient with intra-abdominal infection present with?

A

May follow symptoms consistent with bowel malignancy

e.g. weight loss, alteration of bowel habit, blood in stool etc

78
Q

How could ischaemia cause intra-abdominal infection?

A

Interruption of intestinal blood supply:
Strangulation
Arterial occlusion
Post-operative ( aneurysm repair)

Gut wall loses structural integrity

Allows translocation of the luminal content

79
Q

What are the different causes of post operative infection?

A

Seeding at operation

Anastomotic leak

Acute infection

Intraperitoneal abscess

80
Q

How is seeding in operation reduced?

A

Bowel preparationa nd prophylatic antibiotics

81
Q

What is cholecystitis?

A

Inflammation of the gallbladder wall –> chemical inflammation

82
Q

Is bacterial infection cause of cholecystitis?

A

Bacterial infection may be cause or result of cholecystitis

Cultures positive in c. 50-75% of cases

83
Q

What is cholecystitis assoicated with?

A

Associated with obstruction of the cystic duct

84
Q

What is the cause of obstruction of the cystic duct in cholecystitis?

A

Gallstones (90%)

Other causes
Malignancy, surgery, parasitic worms
Very occasionally no obstruction

85
Q

What is the presentation of cholecystitis?

A

Fever, right upper quadrant pain, mild jaundice (Common bile duct remains patent)

86
Q

What is emphysematous cholecystitis?

A

Intramural gas in gallbladder wall

87
Q

What is the Empyema of the gallbladder?

A

Complication of cholecystitis?

88
Q

What is the cause of Empyema of the gallbladder? How does it present it self?

A

Frank pus in gallbladder

Presentation is as for cholecystitis but septic presentation:
Severe pain
High fever
Chills and rigors

89
Q

What is cholangitis?

A

Inflammation/infection of biliary trea ( hepatic and common bile duct)

90
Q

What is the cause of cholangitis?

A

Mainly obstruction of common bile duct

Can follow instrumentation (e.g. endoscopic retrograde cholangio-pancreatography, ERCP)

91
Q

Presentation of cholangitis?

A

Fever (rigors), jaundice and right upper quadrant pain

Presentation may be non-specific

92
Q

What are the different routes of causing Pyogenic liver abscess?

A

Biliary obstruction

Direct spread from other intra-abdominal infections

Haematogenous

Penetrating trauma

Idipoathic normally found this way

93
Q

What are the two haematogenous routes for causing pyogenic liver abscess?

A

From mesenteric infection
via hepatic portal vein

From systemic intravascular infection
via hepatic artery

94
Q

What is intra-peritoneal abscess?

A

Localised area of peritonitis with build-up of pus.

For example Subphrenic, subhepatic, paracolic, pelvic

95
Q

What are the predisposing factors for intra-peritoneal abscess?

A 
Perforation
Cholecystitis
Mesenteric ischemia/bowel infarction
Pancreatitis/pancreatic necrosis 
Penetrating trauma 
Postoperative anastomotic leak
96
Q

What are the different types of perforation that cause intra-peritoneal abscess?

A

Peptic ulcer
Perforated appendix
Perforated diverticulum

97
Q

Is the development of intra-peritoneal abscess fast acting or slow?

A

Can be a complication that occurs up to several months after the presenation of the predisposing factor

98
Q

What is the non specific presenation of intra-peritoneal abscess?

A

Sweating, anorexia, wasting

High swinging pyrexia

99
Q

What are the localising features of intra-peritoneal abscess?

A

Subphrenic abscess –> accumulation of infected fluid between the diaphragm, the liver and the spleen.

Pelvic abscess

100
Q

What are the features of subprenic abscess? (5)

A

Pain in shoulder on affected side,
Persistent hiccup,
Intercostal tenderness, Apparent hepatomegaly (liver displaced downwards, Ipsilateral lung collapse with pleural effusion

101
Q

What are the 2 features of pelvic abscess?

A

Urinary frequency

Tenesmus –> a continual or recurrent inclination to evacuate the bowels

102
Q

What is spontaenous bacterial peritonitis?

A

 presented by people with chronic liver disease who have bacteria in there peritoneal (no reason for perforation to occur )

Infection of ascitic fluid

103
Q

What is the cause of amoebic abscess?

A

Entamoeba hstolytica?

104
Q

What is the cause of hydatid cyst ?

A

Echinococcus granulosus

Parasite in the liver and causes cyst development

105
Q

How is Illeocaecal tuberculosis found?

A

Cause by M.tuberculosis

Very similar symptoms to TB and found by Ct scan

106
Q

`What 2 aerobic gram negative bacilli causes intra-abdominal infection?

A

Enterobacteriaceae (coliforms) –> predominantly E.coli

Pseudomonas spp.

107
Q

`What 2 anaerobic Gram negative Bacilli causes intra-abdominal infection?

A

Bacteroides spp.,

Prevotella spp.

108
Q

What 2 aerobic Gram positive cocci causes intra-abdominal infection?

A

Enterococcus spp.

Occasionally milleri-group streptococci

109
Q

What aerobic Gram positive bacilli causes intra-abdominal infection?

A

Clostridium spp.

110
Q

What is the cause of Liver abscess?

A

Usally poylmicrobial –> multipel cases

Infections secondary to haematogenous spread or trauma may not involve normal GI flora

111
Q

What does it mean by sterile in terms of liver abscess?

A

The cause of liver abscess is one that is not grown in the lab. It is not one of the usual organisms encountered and therefore does not grow.

112
Q

Where does the flora causing hepatobiliary tract infection orignate from?

A

It is usually flora from the lower GI.

113
Q

How do you diagnose intra-abdominal infections?

A

History

Examination

Investigations
Blood tests
Imaging
Microbiological

114
Q

What blood tests are done for intra-abdominal infections?

A

Full blood count: neutrophilia/neutropenia

C-reactive protein: raised

Liver function tests: abnormal in hepatobiliary disease

115
Q

What imaging do you do in inta-abdominal infections and waht might you see?

A

Chest x-ray
Consolidation, pleural effusion adjacent to infected area (e.g. subphrenic abscess)

Abdominal ultrasound
Abdominal masses
Free fluid
Dilated bile ducts

Abdominal CT scan
Higher definition than ultrasound

116
Q

What samples are tested in microbiological investigations for intra-abdominal infection?

A

Blood
Peritoneal fluid
Ultrasound/CT guided drainage fluid

117
Q

What test are done in the microbiological investigations for intra-abdominal infection?

A

Microscopy, culture and sensitivity testing

118
Q

How is intra-abdominal infections treated?

A

Treat underlying condition
e.g. resection, anastomosis, abscess drainage, biliary drainage

Start Smart… 
Best guess (empirical) antibiotics cover probable infections.

Then focus –> narrow possible spectrum based on culture results

Oral switch –> after 48h

119
Q

What broad based Ab given to patients under the age of 65 with intra-abdominal infection?

A

Cefuroxime & metronidazole

120
Q

What broad based Ab given to patients over the age of 65 with intra-abdominal infection?

A

Piperacillin/tazobactam

Year 2 clinical pathology (21 decks)

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