24 - Intra-abdominal infection Flashcards
Intra-abdominal infection definition
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
What is sterile?
Stomach
Proximal small intestine (growth inhibited by bile)
Flora of large intestine
Anaerobic bacteria (95-99%) Aerobic bacteria - enterobacteriaceae (enteric gram--ve bacilli, coliforms; gram ++Ve cocci)
Sources of intra-ab infection
GI contents
Blood
External
Mechanisms of intra-ab infection
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)
Bloodstream infection causative agents - how is it related to GI?
Clostridium septicum
Streptococcus gallolyticus
Loss of bowel wall integrity due to abnormal malignant tissue
What interrupts intestinal blood supply?
Strangulation
Arterial occlusion
Post-op
Loss of gut wall integrity
Post-op infection
Seeding at operation
Anastomotic leak
Acute infection
Intraperitoneal abscess
What is cholecystitis? +cause
Inflammation of gallbladder wall - chemical inflammation, bacterial infection, obstruction
Types of obstruction of cystic gut
Gallstones (90%)
Malignancy
Surgery
Parasitic worms
Presentation of cholecystitis
Fever, right upper quadrant pain, mild jaundice
Empyema of the gallbladder
Complication of cholecystitis
Frank pus in gallbladder
Presentation is for cholecystitis but septic presentation: severe pain, high fever, chills&rigors.
What is it Cholangitis?
Inflammation of biliary tree
Same causes of cholecystitis
Pyogenic liver abscess route of infection
Biliary obstruction Direct spread from intra-ab infection Haematogenous: mesenteric via HPV; systemic intravascular infection via hepatic artery Penetrating trauma Idipoathic
What is an intra-peritoneal abscess
Localised area of peritonitis with build-up of pus - subphrenic, suphepatic, paracolic, pelvic
Predisposing factors for intra-peritoneal abscess
Perforation - peptic ulcer, perforated appendix/diverticulum Cholecystitis Mesenteric ischaemia Pancreatitis Penetrating trauma Post-op anastomotic leak
Non-specific presentation of intra-peritoneal abscess
Sweating, anorexia, wsating, high swinging pyrexia
Localising features - subphrenic abscess
Pain in shoulder on effected side Persistent hiccup Intercostal tenderness Apparent hepatomegaly If you can't see pus on imaging its under the diaphragm
Localising features - pelvic abscess
Urinary frequency
Tenesmus
Aerobic gram–ve bacilli
Enterobacteriae - mainly E.Coli
Pseudomonas
Anaerobic gram–ve bacilli
Bacteriaodes
Prevotella
Aerobic gram-+ve cocci
Enterococcus
Occasionally milleri-group streptococci
Anaerobic gram-+ve bacilli
Clostridium spp.
Investigations for abscesses
FBC - neutrophilia/neutropenia
C-reactive protein - raised
LFTs - abnormal in hepatobiliary disease
Imaging for intra-ab
Chest x-ray
Ab ultrasound
Ab CT scan
Starting smart for antibiotics
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
Treatment of abscesses
Drain pus out
CT/US guided
Surgical
Combined with antimicrobial therapy
