CP24 - Intra-abdominal Infections

Question 1

which abdominal sites are sterile?

Answer 1

peritoneal cavity
hepatobiliary tree
stomach

Question 2

which organisms are found in the proximal small intestine and why?

Answer 2

aerobic bacteria, candida

microbial growth is inhibited by bile

Question 3

what are the sources of intra-abdominal infection?

Answer 3

GI contents - most common
blood
external, e.g. due to surgical errors (least common)

Question 4

what are the mechanisms of intra-abdominal infections?

Answer 4

1. translocation of micro-organisms from GIT lumen to the peritoneal cavity - intraperitoneal infections
2. translocation of micro-organisms along a lumen - biliary tract/hepatobiliary infections
3. translocation of micro-organisms from extra-intestinal source - penetrating trauma, haematogenous spread

Question 5

how do micro-organisms translocated from GIT lumen to the peritoneal cavity?

Answer 5

1. perforation eg. appendix, ulcers, diverticula, malignancy, could cause sepsis
2. loss of integrity due to ischaemia - eg. blocked vessels or reduced supply
3. loss of integrity due to strangulation- hernia through a tight orifice
4. surgery - anastomotic leak during surgery, if anatomises being performed is not complete

Question 6

how are micro-organisms kept out of the bill duct?

Answer 6

constant outflow of bile out the duct

Question 7

how can bacteria colonise in the hepatobiliary tree?

Answer 7

blockage due to cholecystitis, cholangitis, malignancy, stones, worms or a hepatic abscess could stop the outflow of bile

iatrogenic - through the use of instrumentation

Question 8

what is cholangitis?

Answer 8

inflammation of the bile duct system that is usually related to a bacterial infection
could be iatrogenic

Question 9

what is the pathogenesis of a perforated appendix?

Answer 9

obstruction of lumen of appendix, possible causes include lymphoid hyperplasia or faecal obstruction
causes stagnation of luminal contents, bacterial growth and recruitment of inflammatory cells
build up in pressure could cause perforation

Question 10

what are the clinical features of a perforated appendix?

Answer 10

severe generalised pain
shock
may localise to form an appendix mass
high temperature

Question 11

what is an appendix mass?

Answer 11

an inflamed appendix with adherent covering of momentum and small bowel

Question 12

which micro-organisms can cause infection due to a perforated appendix?

Answer 12

E. coli, bacteroides fragilis

Question 13

how is a perforated appendix treated?

Answer 13

surgery, cefuroxime and metronidazole for 5 days

Question 14

what is the pathogenesis of a perforated diverticulum?

Answer 14

herniations of mucosa or submucosa through the muscular layer, common in the sigmoid or descending colon

Question 15

what are the complications of a diverticulum?

Answer 15

largely asymptomatic
diverticulitis - inflammation of diverticulum, causing pain and disturbance of bowl function
perforation
pericoli abscess - abscess outside the colon

Question 16

what is the pathophysiology of infections causes by a primary bowel cancer?

Answer 16

caused by loss of bowel integrity due to abnormal malignant tissue, but the are infrequent

Question 17

what are the clinical features of an infection caused by bowel malignancy?

Answer 17

consistent with those of the malignancy
weight loss
alteration of bowel habit
blood in stop, etc

Question 18

which species cause infections in bowel cancer?

Answer 18

Clostridium septicum

S. bovis

Question 19

what are the possible causes of post op bowel ischaemia?

Answer 19

1. seeding at operation - spreading of cancer cells during the removal of abnormal tissue. this can be reduced with the use of prophylactic antibiotics
2. anastomotic leak

Question 20

what is the result of bowel leaks during surgery?

Answer 20

acute infection - abode pain, tenderness, shock

intraperitoneal abscess - walled off abscess, more indolent condition

Question 21

what is the pathogenesis of cholecystitis?

Answer 21

inflammation of the gall bladder wall, bacterial infection could occur secondary to this inflammation
potentially due to the obstruction of the cystic duct
common bile duct patent

Question 22

what is emphysematous cholecystitis?

Answer 22

intramural gas in the gall bladder wall

Question 23

what are the clinical features of cholecystitis?

Answer 23

presents with fever
right upper quadrant pain
mild jaundice

Question 24

how does empyema form in the gall bladder?

Answer 24

empyema - frank pus (in the GB)

complication of cholecystitis

Question 25

what are the clinical features of empyema in the gall bladder?

Answer 25

cholecystitis + septic presentation - severe pain, high fever, chills and rigors

Question 26

what is the clinical presentation of cholangitis?

Answer 26

fever with riggers, jaundice and right upper quadrant pain, but representation may be non-specific accompanied by sepsis, shock etc.

Question 27

what are the possible causes of a pyogenic liver abscess?

Answer 27

1. biliary obstruction 2. direct spread from other intra-abdominal infections 3. haematogenous from mesenteric infection (via portal vein) 4. systemic intravascular infection (via hepatic artery) 5. penetrating trauma 6. idiopathic

Question 28

what is an intraperitoneal abscess?

Answer 28

a localised area of peritonitis with a build up of pus | tends to be categorised by its anatomical site

Question 29

where can intraperitoneal abscesses be found?

Answer 29

``` subphrenic sub hepatic parabolic pelvic etc ```

Question 30

what are the predisposing factors for an intra-peritoneal abscess?

Answer 30

1. perforation 2. cholecystitis 3. mesenteric ischaemia/bowel infarction 4. pancreatitis/pancreatic necrosis 5. penetrating trauma 6. post-op anastomotic leak this could be a late complication and present months after the predisposing factor

Question 31

what is the presentation of an intra-peritoneal abscess?

Answer 31

``` non specific sweating anorexia wasting high swinging pyrexia - ```

Question 32

what features in a history can localise an intra-peritoneal abscess to the sub-phrenic region?

Answer 32

pain in shoulder on the affected side persistent hiccup intercostal tenderness apparent hepatomegaly because the pus causes ipsilateral lung collapse with pleural effusion, displacing the liver downwards. could be misdiagnosed as a chest problem!!

Question 33

what features in a history can localise an intra-peritoneal abscess to the pelvic region?

Answer 33

urinary frequency | tenesmus - continual or recurrent inclination to empty bowels

Question 34

what is ascites?

Answer 34

fluid in the peritoneal cavity

Question 35

which conditions cause intra-abdominal sepsis?

Answer 35

1. spontaneous bacterial peritonitis - due to infected ascitic fluid 2. pancreatic and splenic abscesses 3. amoebic abscess - entamoeba histolytica 4. hydatid cyst (parasitic) - enchinococcus granulosus 5. ileo-caecal tb - M. tuberculosis

Question 36

what determines the type of flora causing an intra-abdominal infection?

Answer 36

mode of translocation | if these infections are secondary to haematogenous spread or trauma, the micro-organisms involved may not be GI flora

Question 37

how are intra-abdominal infections generally diagnosed?

Answer 37

1. history 2. exam 3. investigations - bloods - imaging - microbiological investigations

Question 38

what kind of blood tests need to be done to confirm diagnosis of intra-abdominal infections?

Answer 38

FBC to check for neutrophilia/neutropenia CRP - raised LFTs - abnormal in hepatobiliary disease

Question 39

what kind of imaging is required to confirm the diagnosis of an intra-abdominal infection?

Answer 39

CXR to look for consolidation, pleural effusion adjacent to infected area Abdo US to look for abdominal masses, free fluid, dilated bile ducts Abdo CT if HD needed

Question 40

what kind of microbiological investigations need to be done to confirm the diagnosis of an intra-abdominal infection?

Answer 40

sample blood, peritoneal fluid, US, CT guided fluid drainage tests - microscopy, cultures, sensitivity testing

Question 41

what are the general treatment principles for intra-abdominal infections?

Answer 41

treat the underlying condition start smart then focus intestinal source - cefuroxime and metronidazole65y extra intestinal - antibiotic of choice depends on source switch to oral treatment after 48h pyrexial and normal WBCs

Question 42

how should intraperitoneal abscesses be managed?

Answer 42

CT/US guided drainage surgical drainage for multi ocular abscesses combine with antimicrobial therapy