Infection related management of complicated intra-abdominal infection (excluding appendicitis)

Publication: 09/11/2009  
Next review: 18/10/2024  
Clinical Guideline
ID: 1427 
Approved By: Improving Antimicrobial Prescribing Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2021  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.


Complicated intra-abdominal infection is defined as intra-abdominal infections that have extended beyond a hollow viscus of origin into the peritoneal space and are associated with either abscess formation or peritonitis.


For patients with a presumed diagnosis of complicated intra-abdominal infection the following diagnostic tests should be taken to investigate the diagnosis further:

All patients

FBC, U&E and LFTs
Blood cultures taken before empirical treatment is started
Urine culture
Other microbiology e.g., Intra-abdominal pus, wound swabs, sputum samples.
Note: samples of pus in sterile container are preferable to swabs for recovery of pathogens

Selected patients

Radiological tests e.g. Ultrasound scan/CT scan, as clinically indicated.

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EMPIRICAL TREATMENT options for complicated intra-abdominal infection

Review previous microbiology results for presence of antibiotic resistance before starting empirical therapy


Recommended (1st line) treatment

2nd line treatment in penicillin allergy

Duration: please see table below

Empirical treatment
(with sepsis)

If age < 80
Cefuroxime electronic Medicines Compendium information on Cefuroxime IV 1.5g 8-hourly
Metronidazole electronic Medicines Compendium information on Metronidazole PO2 400mg 8-hourly

If age > 80
Piperacillin/tazobactam electronic Medicines Compendium information on Piperacillin/tazobactam IV 4.5g 8-hourly

Teicoplanin electronic Medicines Compendium information on Teicoplanin IV 12mg/kg
(see dosing guidance for frequency) AND
Ciprofloxacin electronic Medicines Compendium information on Ciprofloxacin 1 PO 500mg 12-hourly
Metronidazole electronic Medicines Compendium information on Metronidazole PO2 400mg 8-hourly

Empirical treatment
(without sepsis)


IV to Oral switch

Check microbiology to see if the patient has coliforms with amoxicillin-clavulanic acid resistance. If no resistance:

Co-amoxiclav electronic Medicines Compendium information on Co-amoxiclav 625mg PO 8-hourly
Amoxicillin electronic Medicines Compendium information on Amoxicillin 500mg PO 8-hourly

Check microbiology to see if the patient has coliforms with ciprofloxacin resistance.

If no resistance:
Ciprofloxacin electronic Medicines Compendium information on Ciprofloxacin 500mg PO 12-hourly AND
Metronidazole electronic Medicines Compendium information on Metronidazole 400mg PO 8-hourly.

Teicoplanin electronic Medicines Compendium information on Teicoplanin should continue if evidence of enterococcal infection susceptible to Teicoplanin electronic Medicines Compendium information on Teicoplanin

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We advocate three antibiotic treatment duration strategies which have an evidence base to support. Assessment of a patient’s risk of treatment failure (relapse) or death may feed into consideration of which strategy to select. The choice of strategy will be best selected by a consultant/senior surgeon.

Antibiotic duration strategies


Antibiotic duration

Strategy 1 - Short course

Fixed short course antibiotics in patients who responded quickly to treatment of non-severe infection

4 days treatment with good source control, 7 days without good source control.

Strategy 2 - Clinical assessment

Treat until clinical resolution of symptoms related to infection, and inflammatory markers, have improved- typically 8 to 18 days.

Based on clinical response

Strategy 3 - Fixed-extended-duration

Fixed-extended-duration antibiotic treatment of up to 4 weeks antibiotics

3 to 4 weeks.

Risk of relapse and death

Analysis of observational UK data from patients with cIAI has suggested the following factors MAY be increase a patient’s risk of relapse or death after cIAI diagnosis. These factors can be considered in the choice of antibiotic treatment strategy.

Risk of relapse

Treatment failure
(failure of an initial treatment plan with the need for an unplanned source control procedure or an escalation of antibiotic therapy)

Collections present on imaging

Multiple and large collections

Antimicrobial resistant infections

Risk of death

Age 65 and over

Perforated viscus

Cancer diagnosis

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By 72 hours of antimicrobial treatment, diagnostics may have proven an initial diagnosis or guided to a new diagnosis. If your patient in on IV treatment this should be reviewed daily. The review, outcome and future plans (where appropriate) should be documented in the medical notes. If the diagnosis is still correct your options are now:


If your initial diagnosis is correct and the patient is prescribed IV antibiotics, review whether an oral switch is appropriate using the ACED criteria (see below). If they meet all 4 criteria consider switching using the oral options listed in the table above. 
A - Afebrile for 24 hours
C - Clinically improving
E - Eating and drinking
D- not Deep seated infection
Please note that Intra-abdominal infections may commonly be classed as deep seated but depending on the antibiotic patients may still be eligible for an IVOS.


If no signs of infection and diagnostics support this decision.


If the patient is not clinically responding, check microbiology results to see if directed therapy is required or you may need to consider an alternative diagnosis.


If the patient is improving but does not fully meet ACED criteria. Review daily until ready to switch. Document the reason for continuing.

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Please discuss directed therapy i.e., based on culture results, with microbiology. Isolation of one bacterial species e.g., from a blood culture, may not mean intra-abdominal infection is not polymicrobial.

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  1. Ciprofloxacin electronic Medicines Compendium information on Ciprofloxacin 400mg IV 12 hourly if unable to tolerate PO
  2. Metronidazole electronic Medicines Compendium information on Metronidazole 500mg IV 8 hourly if unable to tolerate PO


Record: 1427
Clinical condition:

Intra-abdominal Infection of Unknown Cause

Target patient group: Adults
Target professional group(s): Secondary Care Doctors
Adapted from:

Evidence base

  • Sawyer RG, Claridge JA, Nathens AB, Rotstein OD, Duane TM, Evans HL, Cook CH, O'Neill PJ, Mazuski JE, Askari R, Wilson MA, Napolitano LM, Namias N, Miller PR, Dellinger EP, Watson CM, Coimbra R, Dent DL, Lowry SF, Cocanour CS, West MA, Banton KL, Cheadle WG, Lipsett PA, Guidry CA, Popovsky K; STOP-IT Trial Investigators. Trial of short-course antimicrobial therapy for intraabdominal infection. N Engl J Med. 2015 May 21;372(21):1996-2005.
  • Ahmed S, Bonnett L, Melhuish A, Adil MT, Aggarwal I, Ali W, Bennett J, Boldock E, Burns FA, Czarniak E, Dennis R, Flower B, Fok R, Goodman A, Halai S, Hanna T, Hashem M, Hodgson SH, Hughes G, Hurndalm KH, Hyland R, Iqbal MR, Jarchow-MacDonald A, Kailavasan M, Klimovskij M, Laliotis A, Lambourne J, Lawday S, Lee F, Lindsey B, Lund JN, Mabayoje DA, Malik KI, Muir A, Narula HS, Ofor U, Parsons H, Pavelle T, Prescott K, Rajgopal A, Roy I, Sagar J, Scarborough C, Shaikh S, Smart CJ, Snape S, Tabaqchali M, Tennakoon A, Tilley R, Vink E, White L, Burke D, Kirby A. Development of clinical prediction models for outcomes of complicated intra-abdominal infection. Br J Surg. 2021 Feb 22:znaa117.
  • Ahmed S, Brown R, Pettinger R, Vargas-Palacios A, Burke D, Kirby A. The CABI Trial: an Unblinded Parallel Group Randomised Controlled Feasibility Trial of Long-Course Antibiotic Therapy (28 Days) Compared with Short Course (≤ 10 Days) in the Prevention of Relapse in Adults Treated for Complicated Intra-Abdominal Infection. J Gastrointest Surg. 2020 Mar 5. doi: 10.1007/s11605-020-04545-2.
  • Montravers P, Tubach F, Lescot T, Veber B, Esposito-Farèse M, Seguin P, Paugam C, Lepape A, Meistelman C, Cousson J, Tesniere A, Plantefeve G, Blasco G, Asehnoune K, Jaber S, Lasocki S, Dupont H; DURAPOP Trial Group. Short-course antibiotic therapy for critically ill patients treated for postoperative intra-abdominal infection: the DURAPOP randomised clinical trial. Intensive Care Med. 2018 Mar;44(3):300-310.

Approved By

Improving Antimicrobial Prescribing Group

Document history

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