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

ACUTE

community-acquired intra-abdominal abscess: non-high risk, mild-to-moderate severity

1st line – source control

Back
ACUTE
|
community-acquired intra-abdominal abscess: non-high risk, mild-to-moderate severity
1st line – 

source control

CT- or ultrasound-guided percutaneous drainage is the first-line therapy for simple abscesses not associated with suspected malignancy or large anastomotic leaks. Useful if only one or two IAA are present (e.g., appendiceal abscess) but limited when trajectory to the abscess requires cross-contaminating a different cavity (e.g., pleura) or when the source of contamination is not sufficiently controlled (e.g., large anastomotic breakdown). Complications include catheter displacement or obstruction, post-procedural septicaemia, and insufficient drainage; may include bleeding and inadvertent injury to surrounding structures.[33] Catheter can be removed when clinical findings disappear and drainage is <10 mL/24 hours; before removal, catheter blockage should be excluded.[38]

Surgical drainage procedure depends on the cause of IAA. When anastomotic leaks occur, a single operation may not suffice, and a 2-stage or multi-stage operation may be required. Haemodynamic instability may contraindicate re-establishing bowel continuity, and a second laparotomy is usually planned within 24 to 48 hours. Negative pressure wound therapy can be considered if the abdomen is left open.[44]

Plus – empirical intravenous broad-spectrum antibiotic therapy

Back
ACUTE
|
community-acquired intra-abdominal abscess: non-high risk, mild-to-moderate severity
Plus – 

empirical intravenous broad-spectrum antibiotic therapy

Treatment recommended for ALL patients in selected patient group

Patients of younger age with no comorbidities, immunosuppression, or organ dysfunction with mild-to-moderate infection and adequate source control (e.g., perforated/abscessed appendicitis), and an Acute Physiology and Chronic Health Evaluation (APACHE) II score <10, are considered non-high risk. Surgical Infection Society: intra-abdominal infection (IAI) high versus low risk Opens in new window

Parenteral empirical antibiotics with broad-spectrum coverage should be initiated promptly. Appropriate cultures should be obtained before initiating antibiotic therapy, but should not prevent their prompt administration.[29]

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Antibiotics should be given before surgical or percutaneous drainage.

Treatment can be with either single-agent or combination regimens, all of which are equally effective. Local resistance patterns should be considered.

Duration of antimicrobial therapy depends on the adequacy of source control and the response to therapy (i.e., resolution of signs and symptoms of infection, and IAA on repeat diagnostic imaging). A multi-centre trial suggests that 4 days of antimicrobial therapy may be sufficient in the setting of adequate source control.[51]

Primary options

ticarcillin/clavulanic acid: 3.1 g intravenously every 6 hours

More

OR

ertapenem: 1 g intravenously every 24 hours

OR

moxifloxacin: 400 mg intravenously every 24 hours

OR

cefuroxime: 1.5 g intravenously every 8 hours

or

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

or

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

-- AND --

metronidazole: 500 mg intravenously every 8-12 hours

OR

ciprofloxacin: 400 mg intravenously every 12 hours

or

levofloxacin: 750 mg intravenously every 24 hours

-- AND --

metronidazole: 500 mg intravenously every 8-12 hours

Plus – switch to targeted antibiotic therapy once cultures known

Back
ACUTE
|
community-acquired intra-abdominal abscess: non-high risk, mild-to-moderate severity
Plus – 

switch to targeted antibiotic therapy once cultures known

Treatment recommended for ALL patients in selected patient group

Patients may be switched to targeted antibiotic therapy once culture results are available.

If the abscess is too small to drain or aspirate (for culture) or the patient has been on antibiotics prior to drainage and there is no growth of organisms, then the patient would remain on empirical antibiotics, assuming there is clinical improvement.

2nd line – further surgical treatment

Back
ACUTE
|
community-acquired intra-abdominal abscess: non-high risk, mild-to-moderate severity
2nd line – 

further surgical treatment

Required if the patient is unresponsive to initial treatment or there is an uncontained leak. A single operation may not sufficiently control the source, and a 2-stage or multi-stage operation may be required.

Haemodynamic instability may contraindicate re-establishing bowel continuity, and a second laparotomy is usually planned within 24 to 48 hours. Negative pressure wound therapy can be considered if the abdomen is left open.[44]

In pyogenic hepatic abscess due to biliary sepsis, a concomitant biliary drainage procedure, whether percutaneous or endoscopic, should be contemplated.

community-acquired intra-abdominal abscess: high risk or high severity

1st line – source control

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
1st line – 

source control

CT- or ultrasound-guided percutaneous drainage is the first-line therapy for simple abscesses not associated with suspected malignancy or large anastomotic leaks. Useful if only one or two IAA are present (e.g., appendiceal abscess) but limited when trajectory to the abscess requires cross-contaminating a different cavity (e.g., pleura) or when the source of contamination is not sufficiently controlled (e.g., large anastomotic breakdown).

Complications include catheter displacement or obstruction, post-procedural septicaemia, and insufficient drainage; may include bleeding and inadvertent injury to surrounding structures.[33]

Catheter can be removed when clinical findings disappear and drainage is <10 mL/24 hours; before removal, catheter blockage should be excluded.[38]

Surgical drainage procedure depends on the cause of IAA. When anastomotic leaks occur, a single operation may not suffice, and a 2-stage or multi-stage operation may be required. Haemodynamic instability may contraindicate re-establishing bowel continuity, and a second laparotomy is usually planned within 24 to 48 hours. Negative pressure wound therapy can be considered if the abdomen is left open.[44]

Plus – empirical intravenous broad-spectrum antibiotic therapy

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Plus – 

empirical intravenous broad-spectrum antibiotic therapy

Treatment recommended for ALL patients in selected patient group

Patients of advanced age with comorbidities (e.g., malignancy), organ dysfunction, malnutrition, low albumin, or immunosuppression, an APACHE II score ≥10, sepsis, or septic shock, and with peritoneal involvement and/or diffuse peritonitis and inadequate source control are considered high risk. Surgical Infection Society: intra-abdominal infection (IAI) high versus low risk Opens in new window

Delay in initial intervention (>24 hours) or prolonged hospitalisation prior to surgery for intra-abdominal infection also place patients at high risk.[2]

In patients with sepsis or septic shock, parenteral empirical antibiotics with broad-spectrum coverage should be initiated immediately after diagnosis as outcome worsens with each hour delay of antimicrobial therapy.[45]

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Local resistance patterns should be considered.

Appropriate cultures should be obtained before initiating antibiotic therapy, but should not prevent their prompt administration.[29]

Antibiotics should be given before surgical or percutaneous drainage.

Duration of antimicrobial therapy depends on the adequacy of source control and the response to therapy (i.e., resolution of signs and symptoms of infection, and IAA on repeat diagnostic imaging). A multi-centre trial suggests that 4 days of antimicrobial therapy may be sufficient in the setting of adequate source control.[51]

Primary options

piperacillin/tazobactam: 3.375 g intravenously every 6 hours

More

OR

imipenem/cilastatin: 500-1000 mg intravenously every 6-8 hours

More

OR

meropenem: 1 g intravenously every 8 hours

OR

ertapenem: 1 g intravenously every 24 hours

OR

ceftazidime: 2 g intravenously every 8 hours

or

cefepime: 2 g intravenously every 8-12 hours

-- AND --

metronidazole: 500 mg intravenously every 8-12 hours

Consider – anti-enterococcal coverage

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Consider – 

anti-enterococcal coverage

Additional treatment recommended for SOME patients in selected patient group

Empirical coverage of Enterococcus should be considered in high-risk patients.[2]

If piperacillin/tazobactam has been used as part of the empirical broad-spectrum antibiotic coverage then Enterococcus is already covered.

Vancomycin-resistant enterococci (VRE) are emerging pathogens that are resistant to many standard antibiotics. Data on the efficacy and safety of specific antimicrobials are limited, particularly with regard to the treatment of intra-abdominal infections. Linezolid is approved for the treatment of VRE infections; daptomycin and tigecycline may also be used.[2]

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Primary options

ampicillin: 2 g intravenously every 4-6 hours

OR

piperacillin/tazobactam: 3.375 g intravenously every 6 hours

More

OR

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

Secondary options

linezolid: 600 mg intravenously every 12 hours

OR

daptomycin: 8-12 mg/kg intravenously every 24 hours

More

OR

tigecycline: 100 mg intravenously initially as a loading dose, followed by 50 mg every 12 hours

Consider – antifungal therapy

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Consider – 

antifungal therapy

Additional treatment recommended for SOME patients in selected patient group

Coverage of Candida is only recommended if there is evidence of infection.[2]

C albicans should be treated with fluconazole, while an echinocandin should be used for fluconazole-resistant Candida species and in critically ill patients.[2]

Primary options

fluconazole: 400-800 mg/day intravenously

Secondary options

caspofungin: 70 mg intravenously on day 1, followed by 50 mg every 24 hours

OR

anidulafungin: 200 mg intravenously on day 1, followed by 100 mg every 24 hours

OR

micafungin: 100 mg intravenously every 24 hours

OR

voriconazole: 6 mg/kg intravenously every 12 hours on day 1, followed by 4 mg/kg every 12 hours

Consider – methicillin-resistant Staphylococcus aureus (MRSA) coverage

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Consider – 

methicillin-resistant Staphylococcus aureus (MRSA) coverage

Additional treatment recommended for SOME patients in selected patient group

Coverage of methicillin-resistant Staphylococcus aureus (MRSA) is only recommended if there is evidence of infection.[2]

Adjunctive vancomycin for MRSA coverage is indicated (if not already in use) in patients known to be colonised with MRSA, or those at risk of MRSA infection because of prior treatment failure or significant antibiotic exposure.[2]

Primary options

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

Consider – extended-spectrum beta-lactamase (ESBL)-producing bacteria coverage

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Consider – 

extended-spectrum beta-lactamase (ESBL)-producing bacteria coverage

Additional treatment recommended for SOME patients in selected patient group

ESBL-producing bacteria are resistant to many extended-spectrum cephalosporins as well as aminoglycosides, sulfonamides, and fluoroquinolones. Carbapenems are the first-line option (if not already in use).[50] Novel combinations of cephalosporins and beta-lactamase inhibitors, such as ceftolozane/tazobactam, have shown some success against some ESBL strains in one phase 3 trial but further trials are needed.[54] Ceftolozane/tazobactam is used in combination with metronidazole.

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Primary options

ertapenem: 1 g intravenously every 24 hours

OR

imipenem/cilastatin: 500-1000 mg intravenously every 6-8 hours

More

OR

meropenem: 1 g intravenously every 8 hours

Secondary options

ceftolozane/tazobactam: 1.5 g intravenously every 8 hours

More

and

metronidazole: 500 mg intravenously every 8-12 hours

Consider – carbapenem-resistant Enterobacteriaceae (CRE) coverage

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Consider – 

carbapenem-resistant Enterobacteriaceae (CRE) coverage

Additional treatment recommended for SOME patients in selected patient group

Options for treatment are limited as many of the carbapenem-resistant bacteria also harbour resistance to other antibiotics. Colistimethate (colistin) or tigecycline are recommended, and polymyxin B and ceftazidime/avibactam may also be used.

Ceftazidime/avibactam has been approved in some countries, including the US, for the treatment of complicated intra-abdominal infections when used in combination with metronidazole. It is recommended for higher-risk patients with strongly suspected or proven infection with Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae, for which other agents are not suitable.[2]

Primary options

tigecycline: 100 mg intravenously initially as a loading dose, followed by 50 mg every 12 hours

OR

colistimethate sodium: consult specialist for guidance on dose

OR

polymyxin B: 15000 - 25000 units intravenously every 12 hours

Secondary options

ceftazidime/avibactam: 2.5 g intravenously every 8 hours

More

and

metronidazole: 500 mg intravenously every 8-12 hours

Plus – switch to targeted antibiotic therapy once cultures known

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
Plus – 

switch to targeted antibiotic therapy once cultures known

Treatment recommended for ALL patients in selected patient group

Patients may be switched to targeted antibiotic therapy once culture results are available.

If the abscess is too small to drain or aspirate (for culture) or the patient has been on antibiotics prior to drainage and there is no growth of organisms, then the patient would remain on empirical antibiotics, assuming there is clinical improvement.

2nd line – further surgical treatment

Back
ACUTE
|
community-acquired intra-abdominal abscess: high risk or high severity
2nd line – 

further surgical treatment

Required if the patient is unresponsive to initial treatment or there is an uncontained leak. A single operation may not sufficiently control the source, and a 2-stage or multi-stage operation may be required.

Haemodynamic instability may contraindicate re-establishing bowel continuity, and a second laparotomy is usually planned within 24 to 48 hours. Negative pressure wound therapy can be considered if the abdomen is left open.[44]

In pyogenic hepatic abscess due to biliary sepsis, a concomitant biliary drainage procedure, whether percutaneous or endoscopic, should be contemplated.

health care-associated intra-abdominal abscess

1st line – source control

Back
ACUTE
|
health care-associated intra-abdominal abscess
1st line – 

source control

CT- or ultrasound-guided percutaneous drainage is the first-line therapy for simple abscesses not associated with suspected malignancy or large anastomotic leaks. Useful if only one or two IAA are present (e.g., appendiceal abscess) but limited when trajectory to the abscess requires cross-contaminating a different cavity (e.g., pleura) or when the source of contamination is not sufficiently controlled (e.g., large anastomotic breakdown). Complications include catheter displacement or obstruction, post-procedural septicaemia, and insufficient drainage; may include bleeding and inadvertent injury to surrounding structures.[33] Catheter can be removed when clinical findings disappear and drainage is <10 mL/24 hours; before removal, catheter blockage should be excluded.[38]

Surgical drainage procedure depends on the cause of IAA. When anastomotic leaks occur, a single operation may not suffice, and a 2-stage or multi-stage operation may be required. Haemodynamic instability may contraindicate re-establishing bowel continuity, and a second laparotomy is usually planned within 24 to 48 hours. Negative pressure wound therapy can be considered if the abdomen is left open.[44]

Plus – empirical intravenous broad-spectrum antibiotic therapy

Back
ACUTE
|
health care-associated intra-abdominal abscess
Plus – 

empirical intravenous broad-spectrum antibiotic therapy

Treatment recommended for ALL patients in selected patient group

In patients with sepsis or septic shock, parenteral empirical antibiotics with broad-spectrum coverage should be initiated immediately after diagnosis as outcome worsens with each hour delay of antimicrobial therapy.[45] Appropriate cultures should be obtained before initiating antibiotic therapy, but should not prevent their prompt administration.[29]

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Antibiotics should be given before surgical or percutaneous drainage.

Duration of antimicrobial therapy depends on the adequacy of source control and the response to therapy (i.e., resolution of signs and symptoms of infection, and IAA on repeat diagnostic imaging). A multi-centre trial suggests that 4 days of antimicrobial therapy may be sufficient in the setting of adequate source control.[51]

Primary options

meropenem: 1 g intravenously every 8 hours

or

imipenem/cilastatin: 500-1000 mg intravenously every 6-8 hours

More

or

piperacillin/tazobactam: 3.375 g intravenously every 6 hours

More

or

ceftazidime: 2 g intravenously every 8 hours

or

cefepime: 2 g intravenously every 8-12 hours

or

gentamicin: 5-7 mg/kg intravenously every 24 hours

or

tobramycin: 5-7 mg/kg intravenously every 24 hours

or

amikacin: 15-20 mg/kg intravenously every 24 hours

-- AND --

metronidazole: 500 mg intravenously every 8-12 hours

Plus – anti-enterococcal coverage

Back
ACUTE
|
health care-associated intra-abdominal abscess
Plus – 

anti-enterococcal coverage

Treatment recommended for ALL patients in selected patient group

Empirical anti-enterococcal therapy against Enterococcus faecalis is recommended, especially for patients with post-operative infection or prosthetic intravascular materials, those who have previously received cephalosporins or other anti-enterococcal antibiotics, and for immunocompromised patients.[2]

If piperacillin/tazobactam has been used as part of the empirical broad-spectrum antibiotic coverage then Enterococcus is already covered.

Vancomycin-resistant enterococci (VRE) are emerging pathogens that are resistant to many standard antibiotics.

Data on the efficacy and safety of specific antimicrobials are limited, particularly with regard to the treatment of intra-abdominal infections. Linezolid is approved for the treatment of VRE infections, and daptomycin or tigecycline may also be used.[2]

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Primary options

ampicillin: 2 g intravenously every 4-6 hours

OR

piperacillin/tazobactam: 3.375 g intravenously every 6 hours

More

OR

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

Secondary options

linezolid: 600 mg intravenously every 12 hours

OR

daptomycin: 8-12 mg/kg intravenously every 24 hours

More

OR

tigecycline: 100 mg intravenously initially as a loading dose, followed by 50 mg every 12 hours

Consider – antifungal therapy

Back
ACUTE
|
health care-associated intra-abdominal abscess
Consider – 

antifungal therapy

Additional treatment recommended for SOME patients in selected patient group

Antifungal therapy is only recommended if Candida is grown from intra-abdominal cultures.

C albicans should be treated with fluconazole, while an echinocandin should be used for fluconazole-resistant Candida species and in critically ill patients.[2]

Primary options

fluconazole: 400-800 mg/day intravenously

Secondary options

caspofungin: 70 mg intravenously on day 1, followed by 50 mg every 24 hours

OR

anidulafungin: 200 mg intravenously on day 1, followed by 100 mg every 24 hours

OR

micafungin: 100 mg intravenously every 24 hours

OR

voriconazole: 6 mg/kg intravenously every 12 hours on day 1, followed by 4 mg/kg every 12 hours

Tertiary options

amphotericin B deoxycholate: 0.6 to 1 mg/kg intravenously every 24 hours

Consider – methicillin-resistant Staphylococcus aureus (MRSA) coverage

Back
ACUTE
|
health care-associated intra-abdominal abscess
Consider – 

methicillin-resistant Staphylococcus aureus (MRSA) coverage

Additional treatment recommended for SOME patients in selected patient group

Coverage of methicillin-resistant Staphylococcus aureus (MRSA) is only recommended if there is evidence of infection.[2]

Adjunctive vancomycin for MRSA coverage is indicated (if not already in use) in patients known to be colonised with MRSA, or those at risk of MRSA infection because of prior treatment failure or significant antibiotic exposure.[2]

Primary options

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

Consider – extended-spectrum beta-lactamase (ESBL)-producing bacteria coverage

Back
ACUTE
|
health care-associated intra-abdominal abscess
Consider – 

extended-spectrum beta-lactamase (ESBL)-producing bacteria coverage

Additional treatment recommended for SOME patients in selected patient group

ESBL-producing bacteria are resistant to many extended-spectrum cephalosporins as well as aminoglycosides, sulfonamides, and fluoroquinolones.

Carbapenems are the first-line option (if not already in use), although ertapenem is not preferred for hospital-acquired ESBL-producing bacterial infections because of lack of significant activity against Pseudomonas or Acinetobacter.[50]

Non-carbapenem antibiotics have been used to treat infections with ESBL-producing bacteria, but there is reluctance to recommend them because of observational studies showing clinical failure of such antibiotics, even when susceptibility in vitro has been demonstrated. Novel combinations of cephalosporins and beta-lactamase inhibitors, such as ceftolozane/tazobactam, have shown some success against some ESBL strains in one phase 3 trial but further trials are needed.[54] Ceftolozane/tazobactam is used in combination with metronidazole.

Two meta-analyses have demonstrated reduced short term mortality using an (off-label) extended-duration infusion of beta-lactams after the initial bolus.[46][47] Doses are not reflected here.

Primary options

imipenem/cilastatin: 500-1000 mg intravenously every 6-8 hours

More

OR

meropenem: 1 g intravenously every 8 hours

Secondary options

ceftolozane/tazobactam: 1.5 g intravenously every 8 hours

More

and

metronidazole: 500 mg intravenously every 8-12 hours

Consider – carbapenem-resistant Enterobacteriaceae (CRE) coverage

Back
ACUTE
|
health care-associated intra-abdominal abscess
Consider – 

carbapenem-resistant Enterobacteriaceae (CRE) coverage

Additional treatment recommended for SOME patients in selected patient group

Options for treatment are limited as many of the carbapenem-resistant bacteria also harbour resistance to other antibiotics. Colistimethate (colistin) or tigecycline are recommended, and polymyxin B and ceftazidime/avibactam may also be used.

Ceftazidime/avibactam has been approved in some countries, including the US, for the treatment of complicated intra-abdominal infections when used in combination with metronidazole. It is recommended for higher-risk patients with strongly suspected or proven infection with Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae, for which other agents are not suitable.[2]

Primary options

tigecycline: 100 mg intravenously initially as a loading dose, followed by 50 mg every 12 hours

OR

colistimethate sodium: consult specialist for guidance on dose

OR

polymyxin B: 15000 - 25000 units intravenously every 12 hours

Secondary options

ceftazidime/avibactam: 2.5 g intravenously every 8 hours

More

and

metronidazole: 500 mg intravenously every 8-12 hours

Plus – switch to targeted antibiotic therapy once cultures known

Back
ACUTE
|
health care-associated intra-abdominal abscess
Plus – 

switch to targeted antibiotic therapy once cultures known

Treatment recommended for ALL patients in selected patient group

Patients may be switched to targeted antibiotic therapy once culture results are available.

If the abscess is too small to drain or aspirate (for culture) or the patient has been on antibiotics prior to drainage and there is no growth of organisms, then the patient would remain on empirical antibiotics, assuming there is clinical improvement.

2nd line – further surgical treatment

Back
ACUTE
|
health care-associated intra-abdominal abscess
2nd line – 

further surgical treatment

Required if the patient is unresponsive to initial treatment or there is an uncontained leak. A single operation may not sufficiently control the source, and a 2-stage or multi-stage operation may be required.

Haemodynamic instability may contraindicate re-establishing bowel continuity, and a second laparotomy is usually planned within 24 to 48 hours. Negative pressure wound therapy can be considered if the abdomen is left open.[44]

In pyogenic hepatic abscess due to biliary sepsis, a concomitant biliary drainage procedure, whether percutaneous or endoscopic, should be contemplated.

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Choose a patient group to see our recommendations

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

Use of this content is subject to our disclaimer