Pyogenic Infection Flashcards
Routes of pyogenic Infection
The potential routes of hepatic exposure to bacteria are
- the biliary tree
- portal vein
- hepatic artery
- direct extension of a nearby nidus of infection
- trauma
What is the MC from this List ?
Infections from the biliary tree are the most common identifiable cause of hepatic abscess.
intrahepatic stones and cholangitis (recurrent pyogenic cholangitis [RPC]) are common causes
whereas in the West, malignant obstruction has become a more predominant cause.
The portal venous system Spread
Portal Venous System drains the gastrointestinal tract
The most common causes of pyelophlebitis :
-diverticulitis
-appendicitis
-pancreatitis
-inflammatory bowel disease
-pelvic inflammatory disease
-perforated viscus
-omphalitis
systemic infection and its route ?
Any systemic infection
- endocarditis
- pneumonia
- osteomyelitis
> > through the hepatic artery
What about Direct Spread
- Hepatic abscess can be the result of direct extension of an infectious process.
Common examples include :
- suppurative cholecystitis
- subphrenic abscess
- perinephric abscess
- perforation of the bowel directly into the liver.
What about Penetrating and blunt trauma
- result in an intrahepatic hematoma or an area of necrotic liver > subsequently develop into an abscess.
- Bacteria may have been introduced from the trauma, or the affected area may be seeded from systemic bacteremia.
- delayed fashion up to several weeks after injury.
- Other mechanisms of iatrogenic hepatic necrosis, such as hepatic artery embolization or, thermal ablative procedures
What about Cryptogenic Abscess ?
- Usually, no cause for a hepatic abscess is found
- colonoscopy and endoscopic retrograde cholangiopancreatography (ERCP) may help ?
- these patients should undergo a thorough history, physical examination, and laboratory workup in search of abnormalities in the intestinal tract or biliary tree.
MC Site for abscess
Most hepatic abscesses involve the right hemiliver, accounting for about 75% of cases
When do you suspect mono bacterial and when multiple ?
Abscesses from pyelophlebitis or cholangitis tend to be polymicrobial with a high preponderance of gram-negative bacilli.
Systemic infections, on the other hand, usually cause infection with a single organism.
The most common organisms cultured are
Escherichia coli and Klebsiella pneumoniae.
Other commonly encountered organisms
- Staphylococcus aureus
- Enterococcus sp
- viridans streptococci
- Bacteroides spp.
Which one is associated with Gas forming abscess ?
Klebsiella is frequently associated with gas-forming abscesses
where do you see Fungal and mycobacterial hepatic abscesses
rare
almost always associated with immunosuppression, usually from chemotherapy.
Which bacteria indicate single organism ?
Enterococci and viridans streptococci are generally found in polymicrobial abscesses
whereas staphylococcal infections are typically caused by a single organism
What causes endogenous endophthalmitis
A rare complication specific to Klebsiella hepatic abscesses is endogenous endophthalmitis,
what do you see in labs ?
Labs are non specific
- Leukocytosis
- anemia
- ALP level is mildly elevated
- total bilirubin concentration
- Transaminases are mildly elevated
- Hypoalbuminemia
- mild elevations of the PT and INR
Us Features and Limitations
- round or oval area that is less echogenic than the surrounding liver.
- The limitations of ultrasound are in its ability to visualize lesions high up in the dome of the liver and that it is a user-dependent modality
CT Features
- Lower attenuation than surrounding hepatic parenchyma.
- abscess wall usually has an intense enhancement on contrast-enhanced CT.
how to differentiate between amoebic and pyogenic
- On serologic testing, Entamoeba histolytica antibodies are almost always present in amebic abscesses
-
TX of Pyogenic Abscess
- broad-spectrum IV antibiotics should be started immediately
- Blood C/S
- abscess C/S from aspiration for aerobic and anaerobic cultures.
- immunosuppressed patients > mycobacterial and fungal cultures of the aspirate should be considered
- risk for amebic infections > amebic serology
- catheter drainage remains the treatment of choice, although a trial of a single aspiration is reasonable to consider
What Abx and Duration
Combinations such as
- ampicillin, an aminoglycoside, and metronidazole
- or a third-generation cephalosporin with metronidazole
- unclear how long to continue antibiotics, but recommendations are usually for 2 weeks or more.
when to do Liver resection
- occasionally required for hepatic abscess.
This may be required for an
- infected hepatic malignant neoplasm
- hepatolithiasis
- intrahepatic biliary stricture.
If hepatic destruction from infection is severe, some patients may benefit from resection
What predict poor prognosis
-The presence of malignant disease
-Signs of chronic disease, such as hypoalbuminemia
- signs of severe infection, such as marked leukocytosis, (APACHE II) scores, abscess rupture, bacteremia, and shock, are also associated with mortality
