Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

INITIAL

suspected pyogenic abscess

1st line – empiric broad-spectrum antibiotic therapy including coverage for resistant organisms

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically unstable
1st line – 

empiric broad-spectrum antibiotic therapy including coverage for resistant organisms

Broad-spectrum antibiotic therapy should be started empirically when the diagnosis of liver abscess is suspected.[40][41]

Initial therapy should target gram-positive, gram-negative, and anaerobic organisms, including Bacteroides species.[8]​​[19]

An antibiotic regimen that is particularly broad in its coverage is commenced when the patient is acutely ill with signs of shock or is receiving care in the intensive care unit (ICU).

Antibiotics that cover gram-negative organisms should be used, including piperacillin/tazobactam in monotherapy; imipenem/cilastatin in monotherapy; meropenem in monotherapy; ertapenem in monotherapy or one of cefepime, ceftriaxone, levofloxacin, or ciprofloxacin given with metronidazole.

A fluoroquinolone may be used when there is beta-lactam resistance or intolerance. A fluoroquinolone should not be used as initial empiric therapy if the rate of fluoroquinolone-resistant E coli exceeds 10% in the hospital or local community. Adverse effects may include tendonitis, tendon rupture, arthralgia, neuropathies, and other musculoskeletal or nervous system effects.[43]

If a patient has risk factors for extended-spectrum beta-lactamase (ESBL)-producing organisms, treatment with a carbapenem antibiotic (e.g., imipenem/cilastatin, meropenem, or ertapenem) while awaiting culture results should be considered. ESBL-producing organisms have broad antibiotic resistance. Risk factors for infection with ESBL-producing organisms include increased length of stay in the hospital or ICU; presence of central venous catheter, arterial catheter, or urinary catheter; increased severity of illness; hemodialysis; ventilatory assistance; emergency abdominal surgery; prior administration of any antibiotic; gut colonization; and use of a gastrostomy or jejunostomy tube.[44][45]

Duration of antibiotic treatment depends on the patient's clinical course and the adequacy of drainage. Parenteral therapy is given initially. If the patient is improving and fever and leukocytosis have resolved, the patient can be switched to an oral anti-infective regimen.[41] Anti-infective agents can be stopped only if clinical symptoms and signs, including fever and leukocytosis, have resolved and the abscess has been adequately drained.[8] Follow-up imaging may help determine when anti-infective agents can be discontinued. The optimal duration of antibiotics for pyogenic liver abscess is not clear. Treatment duration typically ranges from 2 to 6 weeks with longer courses used in patients with hypervirulent Klebsiella pneumoniae, immunocompromise, inadequate source control.[1]​ Normalization of C-reactive protein values may also help determine when antibiotics can be stopped.[27]​ Future studies are needed to determine the optimal duration of antibiotics.

Primary options

piperacillin/tazobactam: 3.375 g intravenously every 6 hours

More

OR

imipenem/cilastatin: 500 mg intravenously every 6 hours

More

OR

meropenem: 1-2 g intravenously every 8 hours

OR

ertapenem: 1 g intravenously every 24 hours

OR

cefepime: 1-2 g intravenously every 8 hours

and

metronidazole: 500 mg intravenously every 8 hours

OR

ceftriaxone: 1-2 g intravenously every 12-24 hours

and

metronidazole: 500 mg intravenously every 8 hours

OR

levofloxacin: 500-750 mg intravenously every 24 hours

and

metronidazole: 500 mg intravenously every 8 hours

OR

ciprofloxacin: 400 mg intravenously every 12 hours

and

metronidazole: 500 mg intravenously every 8 hours

Plus – intravenous fluids + supportive care

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically unstable
Plus – 

intravenous fluids + supportive care

Treatment recommended for ALL patients in selected patient group

In addition, general management of sepsis and septic shock, including resuscitative measures, intravenous fluid replacement, and supportive care, is commenced.[42]

Plus – drainage

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically unstable
Plus – 

drainage

Treatment recommended for ALL patients in selected patient group

Urgent drainage is warranted if patients present with shock or multiorgan dysfunction.

Patients with severe illness and an Acute Physiology and Chronic Health Evaluation (APACHE) II Score (scoring that classifies severity of illness in intensive care unit patients) ≥15 may benefit from surgical resection rather than percutaneous drainage.[57]

Consider – vancomycin

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically unstable
Consider – 

vancomycin

Treatment recommended for SOME patients in selected patient group

Consider adding vancomycin to any of the first-line (primary) antibiotic regimens above if the patient is severely ill, if MRSA or resistant enterococci are suspected, or if there are gram-positive cocci on the Gram stain of the abscess fluid.

Primary options

vancomycin: 15-20 mg/kg intravenously every 8-12 hours

Consider – antifungal therapy

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically unstable
Consider – 

antifungal therapy

Treatment recommended for SOME patients in selected patient group

When liver abscess is diagnosed in a patient who is immunocompromised or neutropenic, additional empiric therapy for Candida species should be considered. It is important to seek advice regarding the management of these patients from an infectious disease specialist.

Various possible antifungal agents may be used, including echinocandins (e.g., caspofungin, anidulafungin, and micafungin) or fluconazole. Fluconazole is indicated only for patients who do not have a prior history of azole antifungal therapy (e.g., patients receiving antifungal prophylaxis for bone marrow transplant).

Treatment course: ≥2 weeks of intravenous therapy depending on clinical course.

Primary options

caspofungin: 70 mg intravenously once daily on day 1, followed by 50 mg once daily

OR

anidulafungin: 200 mg intravenously once daily on day 1, followed by 100 mg once daily

OR

micafungin: 100 mg intravenously once daily

OR

fluconazole: 800 mg intravenously/orally once daily on day 1, followed by 400 mg once daily

1st line – standard empiric broad-spectrum antibiotic therapy

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
1st line – 

standard empiric broad-spectrum antibiotic therapy

Broad-spectrum antibiotic therapy should be started empirically when the diagnosis of liver abscess is suspected.[40][41]​​ In stable patients, antibiotic therapy may be deferred until after drainage or aspiration if the procedure can be performed soon after the diagnosis is suspected.

Initial therapy should target gram-positive, gram-negative, and anaerobic organisms, including Bacteroides species.[8][19]​​

A fluoroquinolone should not be used as initial empiric therapy if the rates of fluoroquinolone-resistant E coli exceed 10% in the hospital or local community. Adverse effects may include tendonitis, tendon rupture, arthralgia, neuropathies, and other musculoskeletal or nervous system effects.[43]

Once the infective organism is confirmed on culture, the regimen can be adjusted appropriately. Any of the fluoroquinolones may be used when there is beta-lactam resistance or intolerance.

Duration of antibiotic treatment depends on the patient's clinical course and the adequacy of drainage. Parenteral therapy is given initially. If the patient is improving and fever and leukocytosis have resolved, the patient can be switched to an oral anti-infective regimen.[41] Anti-infective agents can be stopped only if clinical symptoms and signs, including fever and leukocytosis, have resolved and the abscess has been adequately drained.[8] Follow-up imaging may help determine when anti-infective agents can be discontinued. The optimal duration of antibiotics for pyogenic liver abscess is not clear. Treatment duration typically ranges from 2 to 6 weeks with longer courses used in patients with hypervirulent Klebsiella pneumoniae, immunocompromise, inadequate source control.[1]​ Normalization of C-reactive protein values may also help determine when antibiotics can be stopped.[27] Future studies are needed to determine the optimal duration of antibiotics.​

Primary options

levofloxacin: 500-750 mg intravenously/orally every 24 hours

and

metronidazole: 500 mg intravenously/orally every 8 hours

OR

ciprofloxacin: 400 mg intravenously every 12 hours, or 750 mg orally twice daily

and

metronidazole: 500 mg intravenously/orally every 8 hours

OR

moxifloxacin: 400 mg intravenously/orally every 24 hours

and

metronidazole: 500 mg intravenously/orally every 8 hours

OR

ceftriaxone: 1-2 g intravenously every 12-24 hours

and

metronidazole: 500 mg intravenously every 8 hours

OR

cefotaxime: 1-2 g intravenously every 6-8 hours

and

metronidazole: 500 mg intravenously every 8 hours

Consider – drainage

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
Consider – 

drainage

Treatment recommended for SOME patients in selected patient group

For most abscesses, drainage is an important step in treatment, along with antibiotic therapy. For liver abscesses <3 cm in diameter, antibiotics alone may be sufficient to treat the abscess.[40]

The abscess can be drained by needle aspiration (most commonly under radiographic guidance), placement of an indwelling catheter (most commonly under radiographic guidance), open or laparoscopic surgical drainage, surgical resection of the abscess, or endoscopic drainage (in cases of a biliary origin of infection).

The choice as to which type of drainage procedure is performed depends on several factors, including the size, location, and complexity of the abscess.

Consider – antifungal therapy

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
Consider – 

antifungal therapy

Treatment recommended for SOME patients in selected patient group

When liver abscess is diagnosed in a patient who is immunocompromised or neutropenic, additional empiric therapy for Candida species should be considered. It is important to seek advice regarding the management of these patients from an infectious disease specialist.

Various possible antifungal agents may be used, including echinocandins (e.g., caspofungin, anidulafungin, and micafungin) or fluconazole. Fluconazole is indicated only for patients who do not have a prior history of azole antifungal therapy (e.g., patients receiving antifungal prophylaxis for bone marrow transplant).

Treatment course: ≥2 weeks of intravenous therapy depending on clinical course.

Primary options

caspofungin: 70 mg intravenously once daily on day 1, followed by 50 mg once daily

OR

anidulafungin: 200 mg intravenously once daily on day 1, followed by 100 mg once daily

OR

micafungin: 100 mg intravenously once daily

OR

fluconazole: 800 mg intravenously/orally once daily on day 1, followed by 400 mg once daily

2nd line – alternative empiric broad-spectrum antibiotic therapy

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
2nd line – 

alternative empiric broad-spectrum antibiotic therapy

Alternative antibiotics may be used when drug-resistant or gram-negative pathogens are suspected. Antibiotics that cover gram-negative organisms include piperacillin/tazobactam, imipenem/cilastatin, meropenem, ertapenem, and cefepime administered with metronidazole.

A carbapenem antibiotic (e.g., imipenem/cilastatin, meropenem, or ertapenem) should be considered with risk factors for extended-spectrum beta-lactamase-producing organisms. Risk factors include increased length of stay in the hospital or intensive care unit; presence of central venous catheter, arterial catheter, or urinary catheter; increased severity of illness; hemodialysis; ventilatory assistance; emergency abdominal surgery; prior administration of any antibiotic; gut colonization; and use of a gastrostomy or jejunostomy tube.[44][45]

If amebic abscess is considered (not as the most likely diagnosis but as a consideration along with other infective causes of liver abscess), then metronidazole should be included as part of the antibiotic regimen. This is preferable to using tinidazole because metronidazole also covers anaerobic pathogens.

Duration of antibiotic treatment depends on the patient's clinical course and the adequacy of drainage. Parenteral therapy is given initially. If the patient is improving and fever and leukocytosis have resolved, the patient can be switched to an oral anti-infective regimen.[41] Anti-infective agents can be stopped only if clinical symptoms and signs, including fever and leukocytosis, have resolved and the abscess has been adequately drained.[8] Follow-up imaging may help determine when anti-infective agents can be discontinued. The optimal duration of antibiotics for pyogenic liver abscess is not clear. Treatment duration typically ranges from 2 to 6 weeks with longer courses used in patients with hypervirulent Klebsiella pneumoniae, immunocompromise, inadequate source control.[1]​ Normalization of C-reactive protein values may also help determine when antibiotics can be stopped.[27]​ Future studies are needed to determine the optimal duration of antibiotics.

Primary options

piperacillin/tazobactam: 3.375 g intravenously every 6 hours

More

OR

imipenem/cilastatin: 500 mg intravenously every 6 hours

More

OR

meropenem: 1-2 g intravenously every 8 hours

OR

ertapenem: 1 g intravenously every 24 hours

More

OR

cefepime: 1-2 g intravenously every 8 hours

and

metronidazole: 500 mg intravenously every 8 hours

Consider – vancomycin

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
Consider – 

vancomycin

Treatment recommended for SOME patients in selected patient group

Vancomycin may be included when the patient is not improving with first-line antibiotics, when Gram stain reveals gram-positive cocci, or when a resistant enterococcal or staphylococcal infection is suspected.

Primary options

vancomycin: 15-20 mg/kg intravenously every 8-12 hours

Consider – drainage

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
Consider – 

drainage

Treatment recommended for SOME patients in selected patient group

For most abscesses, drainage is an important step in treatment, along with antibiotic therapy. For liver abscesses <3 cm in diameter, antibiotics alone may be sufficient to treat the abscess.[40]

The abscess can be drained by needle aspiration (most commonly under radiographic guidance), placement of an indwelling catheter (most commonly under radiographic guidance), open or laparoscopic surgical drainage, surgical resection of the abscess, or endoscopic drainage (in cases of a biliary origin of infection).

The choice as to which type of drainage procedure is performed depends on several factors, including the size, location, and complexity of the abscess.

Consider – antifungal therapy

Back
INITIAL
|
suspected pyogenic abscess
|
hemodynamically stable
Consider – 

antifungal therapy

Treatment recommended for SOME patients in selected patient group

When liver abscess is diagnosed in a patient who is immunocompromised or neutropenic, additional empiric therapy for Candida species should be considered. It is important to seek advice regarding the management of these patients from an infectious disease specialist.

Various possible antifungal agents may be used, including echinocandins (e.g., caspofungin, anidulafungin, and micafungin) or fluconazole. Fluconazole is indicated only for patients who do not have a prior history of azole antifungal therapy (e.g., patients receiving antifungal prophylaxis for bone marrow transplant).

Treatment course: ≥2 weeks of intravenous therapy depending on clinical course.

Primary options

caspofungin: 70 mg intravenously once daily on day 1, followed by 50 mg once daily

OR

anidulafungin: 200 mg intravenously once daily on day 1, followed by 100 mg once daily

OR

micafungin: 100 mg intravenously once daily

OR

fluconazole: 800 mg intravenously/orally once daily on day 1, followed by 400 mg once daily

suspected amebic abscess

1st line – nitroimidazole

Back
INITIAL
|
suspected amebic abscess
1st line – 

nitroimidazole

Patients with amebic liver abscess (either confirmed or presumed highly likely as the cause of the abscess) are treated with a nitroimidazole.[60][61][68] If a patient is unable to take oral medications or is severely ill, intravenous metronidazole can be used.

Treatment course: 7-10 days (metronidazole) or 3 days (tinidazole).

Primary options

metronidazole: 500-750 mg orally three times daily; or 500 mg intravenously every 8 hours

OR

tinidazole: 2000 mg orally once daily

Consider – drainage

Back
INITIAL
|
suspected amebic abscess
Consider – 

drainage

Treatment recommended for SOME patients in selected patient group

Drainage of the abscess is not usually required but is necessary if the patient does not respond to antibiotic therapy, the abscess is >5 cm in diameter, there are left-lobe lesions, there is high risk of rupture, or the exact diagnosis is still in doubt.[11][60][61][62]

Percutaneous drainage is the most common method, but other drainage techniques (e.g., surgical drainage) may be used.

ACUTE

pyogenic abscess: following response to intravenous antibiotic therapy

1st line – switch to oral therapy

Back
ACUTE
|
pyogenic abscess: following response to intravenous antibiotic therapy
1st line – 

switch to oral therapy

The duration of antibiotic therapy (with or without antifungal therapy) depends on the patient's clinical course and the adequacy of drainage.

Parenteral therapy is given initially. If the patient is improving and fever and leukocytosis have resolved, the patient can be switched to an oral antibiotic (with or without oral antifungal) regimen.[41] The choice of oral regimen depends on the specific pathogen isolated and the reported sensitivities.

Antibiotics and antifungals can be stopped only if clinical symptoms and signs, including fever and leukocytosis, have resolved and the abscess has been adequately drained.[8] Normalization of C-reactive protein values may help determine when antibiotics can be stopped.[27] Follow-up imaging may also help determine when antibiotics and antifungals can be discontinued. The optimal duration of antibiotics for pyogenic liver abscess is not clear. Treatment duration typically ranges from 2 to 6 weeks with longer courses used in patients with hypervirulent Klebsiella pneumoniae, immunocompromise, inadequate source control.[1]​ Future studies are needed to determine the optimal duration of antibiotics.

Oral regimens should be based on antimicrobial susceptibilities.

Adverse effects of fluoroquinolones may include tendonitis, tendon rupture, arthralgia, neuropathies, and other musculoskeletal or nervous system effects.[43]

Primary options

levofloxacin: 500-750 mg orally every 24 hours

and

metronidazole: 500 mg orally every 8 hours

OR

ciprofloxacin: 500-750 mg orally twice daily

and

metronidazole: 500 mg orally every 8 hours

OR

moxifloxacin: 400 mg orally every 24 hours

and

metronidazole: 500 mg orally every 8 hours

OR

amoxicillin/clavulanate: 500 mg orally every 8 hours, or 875 mg orally every 12 hours, or 2000 mg orally (extended-release) every 12 hours

amebic abscess: following response to nitroimidazole therapy

1st line – luminal agent

Back
ACUTE
|
amebic abscess: following response to nitroimidazole therapy
1st line – 

luminal agent

Patients who have responded to treatment for amebic abscess with nitroimidazoles, with or without aspiration, should also be commenced on a luminal agent (e.g., paromomycin) to eradicate gut colonization and prevent relapse of amebiasis.[65] This is commenced following completion of the acute antibiotic course.

Treatment course: 7 days.

Primary options

paromomycin: 25-35 mg/kg/day orally given in 3 divided doses

ONGOING

abscess recurrence

1st line – retreatment + investigation for biliary abnormalities

Back
ONGOING
|
abscess recurrence
1st line – 

retreatment + investigation for biliary abnormalities

There are no set guidelines or recommendations for treatment of a recurrent abscess that differ from the first occurrence. Patients with underlying biliary disease have the highest rate of recurrence (25%).[66]​ Potential etiologies include biliary obstruction and a fistula between the biliary tree and the intestine. If a liver abscess recurs, the authors would recommend that expert consultation by a gastroenterologist and investigation for biliary abnormalities by endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography should be considered.​

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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