A.PYOGENIC
• Intraabdominal infection
• Middle to older age (median age 51)
• M = F
ETIOLOGIES
• 35 % : Biliary tract diseases cholangitis or acute cholecystitis
• 30 % : diverticulitis, crohn’s, ulcerative colitis, bowel perforation
• 15% direct extension from a contiguous source : subphreric abscess or empyema of the gallbladder
• Intraabdominal infections : bacterial seeding via portal vein can occur dental disease, endocarditis ; Other Causes : Malignancy
PATHOPYSIOLOGY
• Organism : gram (-) E.Coli 50-70%, gram (+) 25% & anaerob 50%
• Abscess from biliary tend to be multiple & small, both lobes
• Septic emboli via portal vein & contigous source tend to solitary
B. AMEBIC
• Colonic infection with invasive Entamoeba histolytica
• Younger population (30-40 years)
• M > F
ETIOLOGIES
Bile is lethal to amebas, thus infection of gall bladder & bile duct do not occur
PATHOPYSIOLOGY
• Usually arise from colonic infection w. invasive E.histolytica
• Solitary & large, most common right lobe
• Bile is lethal to amebas ? infection of gallbladder or bile duct do not occur
• Ingestion contaminated water or food containing E. histolytica cysts –
• infective cyst form of the parasite survives passage through the stomach and small intestine.
• Excystation occurs in the bowel lumen, where motile and potentially invasive trophozoites are formed.
• In most infections the trophozoites aggregate in the intestinal mucin layer and form new cysts, resulting in a self-limited and asymptomatic infection.
• In some cases, adherence to and lysis of the colonic epithelium, mediated
• by the galactose and N-acetyl-D-galactosamine (Gal/GalNAc)–specific lectin, initiates invasion of the colon ? neutrophils responding to the invasion contribute to cellular damage.
• Once the intestinal epithelium is invaded, extraintestinal spread to the peritoneum, liver, and other sites may follow.
Clinical Manifestation
| PYOGENIC | AMEBIC |
| Nonspesific, fever (absent in 30%), chills, RUQ pain (45%), malaise, weight lose | More severe RUQ pain, fever 90% cases |
| Dominate by underlying disease : appendicitis, diverticulitis, biliary disease | Recent travel to endemic area, but maybe remote |
| Comorbid common : DM, malignancy, alcholism, cardiovascular, chronic renal disease | Previous colonic amebiasis (only 5-15%), concurrent hepatic abcess & amebic dysenteri are unusual |
| Eosinophilia, high bilirubin, blood culture + 50%, aspirates + bacteria 75-90% | Most aspiration does not yield an organism (tropozoite < 20%); odorless, serologic + only invasive amebiasis, negative asymptomatic carrier, gel diffusion precipitin (best test) |
Laboratory And Diagnostic
• Routine lab not diagnostic for both abcess : WBC (?), anemia (normocytic normochromic), sed rate (?)
• LFT nonspesific : 90% high AP, AST/ALT ? but to a lesser degree, low albumin (<2mg%) poor prognostic
• CXR : 50-80% abnormal (RLL atelectasis, R pleural eff, R hemidiaphragm elevation)
• U/S initial test of choice : noninvasive, high sensitivity 80-90%; to distinguish cyst from solid lesion/visualizing biliary tree
• CT (IV contrast) : smaller abcess, asses peritoneal cavity
ASPIRATE
• Amebic aspiration : pyogenic can’t be roled out, respond to amebic therapy has not occurred within 24-48 hours, abcess is large (size greater than 5 cm) & painful
• Surgical drainage of amebic abcess : located in left lobe, respon therapy is not dramatic in 4-5 days
Treatment
PYOGENIC :
• Antibiotic : aminoglicoside/ cephalosporin (gram -), clindamycin/metronidazole (anaerobes), penicillin/ampicillin (enterococci)
• Surgery percutaneus drainage : conservative measure fail, to treat primary intraabdominal lesion
76% cure rate, 60% either alone
AMEBIC:
• Metronidazole drug active against extraintestinal form of amebiasis : 750mg TID x 10 days
• Eradicates intestinal form : iodoquinol 650mg TID x 20 days
• Consider aspiration if failing therapy
Complication And Prognosis
| PYOGENIC | AMEBIC |
| Untreated 100% mortality | Rapid clinical improvement is observed in less than 1 week with antiamebic drug therapy alone |
| Ruptur into peritoneal cavity : subphrenic, perihepatic, subhepatic abscesses or peritonitis; metastatic ruptur emboli (lung, brain) | similar |
| Left lobe abscess : cardiac tamponade, pericarditis | Abscess in dome of liver or complicated by bronchopleural fistula |
| Depends on rapidity diagnosis & underlying illness | Generally do well with treatment |
| Morbidity high (50%), mortality 5-10% (prompt recognation & adequate AB) higher in multipel abscesses | Morbidity 4.5%, mortality 2.2% |