24 - Intra-abdominal infection

Question 1

Intra-abdominal infection definition

Answer 1

Presence of micro-organisms in normally-sterile sites within the ab cavity - peritoneal cavity, hepatobiliary tree

Excludes gastroenteritis as bowel luman is a non-sterile site

Question 2

What is sterile?

Answer 2

Stomach

Proximal small intestine (growth inhibited by bile)

Question 3

Flora of large intestine

Answer 3

Anaerobic bacteria (95-99%)
Aerobic bacteria - enterobacteriaceae (enteric gram--ve bacilli, coliforms; gram ++Ve cocci)

Question 4

Sources of intra-ab infection

Answer 4

GI contents
Blood
External

Question 5

Mechanisms of intra-ab infection

Answer 5

Translocation of micro-organisms from GI tract lumen to peritoneal cavity

Translocation of microorganisms along a lumen (hepatobiliary infection)

Translocation of micro-organisms from extra-intestinal source (trauma)

Question 6

Bloodstream infection causative agents - how is it related to GI?

Answer 6

Clostridium septicum
Streptococcus gallolyticus

Loss of bowel wall integrity due to abnormal malignant tissue

Question 7

What interrupts intestinal blood supply?

Answer 7

Strangulation
Arterial occlusion
Post-op
Loss of gut wall integrity

Question 8

Post-op infection

Answer 8

Seeding at operation
Anastomotic leak
Acute infection
Intraperitoneal abscess

Question 9

What is cholecystitis? +cause

Answer 9

Inflammation of gallbladder wall - chemical inflammation, bacterial infection, obstruction

Question 10

Types of obstruction of cystic gut

Answer 10

Gallstones (90%)
Malignancy
Surgery
Parasitic worms

Question 11

Presentation of cholecystitis

Answer 11

Fever, right upper quadrant pain, mild jaundice

Question 12

Empyema of the gallbladder

Answer 12

Complication of cholecystitis
Frank pus in gallbladder
Presentation is for cholecystitis but septic presentation: severe pain, high fever, chills&rigors.

Question 13

What is it Cholangitis?

Answer 13

Inflammation of biliary tree

Same causes of cholecystitis

Question 14

Pyogenic liver abscess route of infection

Answer 14

Biliary obstruction
Direct spread from intra-ab infection
Haematogenous: mesenteric via HPV; systemic intravascular infection via hepatic artery
Penetrating trauma
Idipoathic

Question 15

What is an intra-peritoneal abscess

Answer 15

Localised area of peritonitis with build-up of pus - subphrenic, suphepatic, paracolic, pelvic

Question 16

Predisposing factors for intra-peritoneal abscess

Answer 16

Perforation - peptic ulcer, perforated appendix/diverticulum
Cholecystitis
Mesenteric ischaemia
Pancreatitis
Penetrating trauma
Post-op anastomotic leak

Question 17

Non-specific presentation of intra-peritoneal abscess

Answer 17

Sweating, anorexia, wsating, high swinging pyrexia

Question 18

Localising features - subphrenic abscess

Answer 18

Pain in shoulder on effected side
Persistent hiccup
Intercostal tenderness
Apparent hepatomegaly
If you can't see pus on imaging its under the diaphragm

Question 19

Localising features - pelvic abscess

Answer 19

Urinary frequency

Tenesmus

Question 20

Aerobic gram–ve bacilli

Answer 20

Enterobacteriae - mainly E.Coli

Pseudomonas

Question 21

Anaerobic gram–ve bacilli

Answer 21

Bacteriaodes

Prevotella

Question 22

Aerobic gram-+ve cocci

Answer 22

Enterococcus

Occasionally milleri-group streptococci

Question 23

Anaerobic gram-+ve bacilli

Answer 23

Clostridium spp.

Question 24

Investigations for abscesses

Answer 24

FBC - neutrophilia/neutropenia
C-reactive protein - raised
LFTs - abnormal in hepatobiliary disease

Question 25

Imaging for intra-ab

Answer 25

Chest x-ray
Ab ultrasound
Ab CT scan

Question 26

Starting smart for antibiotics

Answer 26

Best guess (empirical) antibiotics
Intestinal source: 'coliforms' and anaerobes. 
Cefuroxime & metronidazole 65yo)

Extraintestinal source: antibiotic choice

Then focus

Oral switch - after 48h apyrexial with normal white cell count

Question 27

Treatment of abscesses

Answer 27

Drain pus out
CT/US guided
Surgical
Combined with antimicrobial therapy