Intra-abdominal infections

Question 1

What is an intra-abdominal infection?

Answer 1

presence of micro-organisms in normally sterile sites within the abdominal cavity, not in the GI Tract e.g.
peritoneal cavity
hepatobilary tree

Question 2

Describe the normal flora in the stomach

Answer 2

Stomach = sterile

Question 3

Describe the normal flora in the small intestine

Answer 3

proximal small intestine = free of microorganisms (unless abnormal bowel which has more microorganisms in the small bowel)
growth inhibited by bowel
few aerobic bacteria and candida
distal small intestinal flora reflects large intestine

Question 4

Describe the normal flora of the large intestine

Answer 4

very densely filled with microorganisms
mainly anaerboic bacteria
some aerobic bacteria e.g. enterobacteriaceae, gram +ve cocci

Question 5

what is the rule when prescribing antibiotics?

Answer 5

Start SMART then FOCUS

Question 6

What are the sources of intra-abdominal infection?

Answer 6

GI contents - mainly
blood
external e.g. surgery - unusual

Question 7

What are the 3 different mechanisms by which intra-abdominal infections occur?

Answer 7

1) intraperitoneal infections - translocation from GI tract lumen to peritoneal cavity
2) Billary tract/hepatobilary infections - translocation of organisms along the lumen
3) penetrating trauma/haematogenous spread - translocation from an extra-intestinal source

Question 8

What are examples of causes of translocation across a wall?

Answer 8

perforation (most common cause)
loss of integrity
surgery

Question 9

What are examples for perforation that allow translocation of organisms across a wall?

Answer 9

perforated appendix - younger people
perforated ulcer - in duodenum/stomach, can cause systemic candida infection
perforated diverticulum - older people
malignancy - e.g. bowel cancer

Question 10

What are examples for loss of integrity that allow translocation of organisms across a wall?

Answer 10

ischemia - blood supply acutely blocked off

strangulation - e.g. hernia, blood supply suddenly interupted

Question 11

What are examples for surgery that allow translocation of organisms across a wall?

Answer 11

seeding at operation - leakage of bowel content into perineum, can be avoided by single dose antibiotics before surgery
anastomotic leak - during/after an opertation

Question 12

Give the 2 ways the translaction across a lumen can occur

Answer 12

Blockage

Iatrogenic

Question 13

What are examples for blockage that allow translocation of organisms along a lumen?

Answer 13

cholecystitis
cholangitis
hepatic abscesses

Question 14

What are examples for iatrogenic that allow translocation of organisms along a lumen?

Answer 14

instrumentation e.g. endoscopic retrograde cholangiopancreatography - removing stones from biliary tree pushes the organisms further up

Question 15

What causes perforation of the appendix?

Answer 15

obstruction of lumen of veriform appendix
e.g. lymphnoid hyperplasia
faecal obstruction
→ stagnation of luminal contents, bacterial growth and inflammatory cells
→ build up of pressure = perforation

Question 16

What are the symptoms of perforation of the appendix?

Answer 16

severe, generalised pain
shock - gram -ve bacilli
appendix mass - inflammed appendix with covering od amentum and small bowel

Question 17

What causes perforation of the diverticulum?

Answer 17

herniations of mucosa/submucosa through muscular layer in sigmoid and descending colon → infection/inflammation → perforation

Question 18

Who most commonly has diverticuli?

Answer 18

older people

Question 19

What are other systemic symptoms of bowel cancer?

Answer 19

weight loss
alteration in bowel habit
blood in stool
abdominal pain

Question 20

What is ischemia and what causes ischemia?

Answer 20

interruption of intestinal blood supply e.g. strangulation, arterial occlusion, post op (aneurysm repair)
gut wall loses structural intergrity

Question 21

What are the examples of post operative infections that cause intra-abdominal infections?

Answer 21

Seeding in operation - faeces escaping bowl into peritoneal cavity, antibiotics givenpre op just incase
anastomotic leak - lets bowel contents come out if surgery not done properly or join breaks down
acute infection - abdominal pain/tenderness, shock
intraperitoneal abscesses - walled off, indolent conditions i.e. symptoms some weeks after surgery

Question 22

What is cholecystitis?

Answer 22

inflammation of the gallbladder wall
flow of bile allows ducts to remain sterile therefore no flow = infection
chemical inflammation
bacterial infection

Question 23

What else is associated with cholecystitis?

Answer 23

gallstones

Question 24

What are the typical presentations of cholecystitis?

Answer 24

fever
right upper quadrent pain
mild jaundice (common bile duct remains patent)

Question 25

What is the typical presentation of empyema of the gallbladder?

Answer 25

``` severe pain high fever chills rigors septic + cholecystitis presentation ```

Question 26

What is cholangitis?

Answer 26

inflammation/infection of biliary tree

Question 27

What are the causes of cholangitis?

Answer 27

same as cholecystitis mainly obstruction of common bile duct can follow instrumentation

Question 28

What is the typical presentation cholangitis?

Answer 28

``` fever rigors jaundice right upper quadrent pain may be non specific ```

Question 29

What is pyogenic liver abscesses a complication of?

Answer 29

Cholangitis

Question 30

What is pyogenic liver abscesses?

Answer 30

collection of pus on the liver

Question 31

What are the causes of pyogenic liver abscesses?

Answer 31

bilary obstruction direct spread from other intra-abdominal infections haematogenous i.e. from mesenteric infection via the hepatic portal vein or systemic intravascular infection via hepatic artery (endocarditis) penetrating trauma idiopathic

Question 32

What are intra-peritoneal abscesses?

Answer 32

``` localised are or peritonitis with build up of pus subphrenic - under the diaphram sub hepatic - under the liver paracolic pelvis ```

Question 33

What is the typical presentation of intra peritoneal abscesses?

Answer 33

sweating anarexia wasting high swinging pyrexia - temperature fluctuates up and down

Question 34

What is the typical presentation of subphrenic intra peritoneal abscesses specifically?

Answer 34

``` pain in shoulder of affected side persistant hiccups (phrenic nerve?) intercostal tenderness hepatomegaly - liver displaced downwards, ipsilateral lung collapse with pleural effusion ```

Question 35

What are the best antibiotics to start therapy with in intra-abdominal infections?

Answer 35

>65 = Cefuroxime/metronidaxole