This chapter will review the guidelines by the Infectious Diseases Society of America (IDSA).
Note: Empiric antibiotics should be tailored based on local pathogen prevalence and antibiotic susceptibility, pathogen-specific risk factors, and previous pathogens and antibiotic exposure. Once final culture and susceptibility results become available, empiric antibiotics should be optimized according to the identified pathogen(s) and susceptibility.
Complicated intra-abdominal infection
Definition
IDSA and Surgical Infection Society define complicated intra-abdominal infection as infection extending beyond the hollow viscus of origin into the peritoneal space that is associated with abscess formation or peritonitis.
Risk factors for source control failure
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Delay in treatment (>24 h)
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High severity of illness (Acute Physiology and Chronic Health Evaluation II score ≥15)
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Age >70 years
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Medical comorbidity
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Degree of organ dysfunction
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Low albumin
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Poor nutritional status
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Degree of peritoneal involvement or diffuse peritonitis
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Inability to achieve adequate debridement or drainage
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Malignancy
Pathogens in order of prevalence
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Escherichia coli
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Bacteroides species
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Streptococcus species
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Clostridium species
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Peptostreptococcus species, Eubacterium species
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Klebsiella species, Pseudomonas aeruginosa
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Prevotella species, Enterococcus faecalis
Treatment
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Antibiotic regimen ( Table 10.1 )
Table 10.1
TYPE OF INFECTION
ANTIBIOTIC REGIMEN
Community-Acquired Extra-Biliary Intra-Abdominal Infection
Mild-moderate severity
High severity
Biliary Intra-Abdominal Infection
Community-acquired acute cholecystitis of mild to moderate severity
Cefazolin
Cefuroxime
Ceftriaxone
Community-acquired acute cholecystitis of high severity or acute cholangitis following bilio-enteric anastomosis
Health care–associated biliary infection
Vancomycin plus one of the following:
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Imipenem-cilastatin
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Meropenem
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Doripenem
Health Care–Associated Intra-Abdominal Infection
<20% resistant Pseudomonas aeruginosa , ESBL-producing Enterobacteriaceae , Acinetobacter , or other MDR GNB
Imipenem-cilastatin
Meropenem
Doripenem
Piperacillin-tazobactam
Cefepime + metronidazole
Ceftazidime + metronidazole
ESBL-producing Enterobacteriaceae , Pseudomonas aeruginosa >20% resistant to ceftazidime
Imipenem-cilastatin
Meropenem
Doripenem
Piperacillin-tazobactam
Aminoglycoside
MRSA
Vancomycin
a Recommend reviewing local population susceptibility reports given increasing resistance of Escherichia coli to fluoroquinolones
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Antibiotic dosing ( Table 10.2 )
Table 10.2
ANTIBIOTIC
STANDARD DOSE (IV)
RENAL DOSING
COMMENTS
Β-Lactam/β-Lactamase Inhibitor Combination
Piperacillin-tazobactam
Non-PSA: 3.375 g q6h
PSA: 4.5 g q6h
Off-label extended infusion:
3.375–4.5 g ×1 over 30 min, followed 4 h later by 4 h infusion q8h
Carbapenems (Cross-Sensitivity With PCN Allergy)
Doripenem
500 mg q8h
Similar spectrum of activity as meropenem except more potent in vitro activity against PSA than meropenem
Ertapenem
1 g q24h
CrCl ≤30 and HD: 500 mg daily
Compared to imipenem or meropenem, less active against PSA, Acinetobacter , enterococci , and PCN-resistant pneumococci
Imipenem-cilastatin
500 mg q6h or 1 g q8h
CrCl 60–89: 500 mg q6h
CrCl 30–59: 500 mg q8h
CrCl 15–29 and HD: 500 mg q12h a
CrCl <15 without HD: avoid use
Consider decreasing dose in patients <70 kg to prevent seizures
Meropenem
1 g q8h
CrCl 26–50: same dose q12h
CrCl 10–25: half dose q12h
CrCl <10: half dose q24h
HD: 500 mg q24h a
Similar spectrum of activity as imipenem; slightly lower risk of seizures than imipenem
Cephalosporins (10% Cross-Sensitivity With PCN Allergy)
Cefazolin
1–2 g q8h
CrCl 11–34: 50% dose q12h
CrCl ≤10 and HD: 50% dose q24h a
—
Cefepime
2 g q8–12h
CrCl 30–60: 2 g q12–24h
CrCl <30: 1–2 g q24h
HD: 0.5–1 g q24h a
Risk of seizures in renal insufficiency
Cefotaxime
2 g q8h
CrCl <20: 50% dose q8h
HD: 1–2 g q24h a
—
Cefoxitin
2 g q6h
CrCl 30–50: 2 g q8–12h
CrCl 10–29: 2 g q12–24h
CrCl 5–9: 2 g ×1 then 1 g q12–24h
CrCl <5 and HD: 2 g ×1 then 1 g q24–48h a
—
Ceftazidime
2 g q8h
CrCl 31–50: 2 g q12h
CrCl 16–30: 2 g q24h
CrCl ≤15 and HD: 1 g q24h a
Possible cross-sensitivity between aztreonam and ceftazidime (<5%); avoid aztreonam if history of life-threatening reaction or anaphylaxis to ceftazidime. Other cephalosporins do not have the same risk as ceftazidime
Ceftriaxone
2 g q24h
—
—
Cefuroxime (Zinacef)
1.5 g q8h
CrCl 10–20: 1.5 g q12h
CrCl <10 and HD: 1.5 g q24h a
—
Ceftazidime 2 g-avibactam 0.5 g (Avycaz 2.5 g)
2.5 g q8h
CrCl 31–50: 1.25 g q8h
CrCl 16–30: 0.94 g q12h
CrCl 6–15: 0.94 g q24h
CrCl ≤5 and HD: 0.94 g q48h a
Reserve for MDR PSA, and ESBL- and KPC-producing Enterobacteriaceae.
Combine with metronidazole
Ceftolozane 1 g-tazobactam 0.5 g (Zerbaxa 1.5 g)
1.5 g q8h
CrCl 30–50: 750 mg q8h
CrCl 15–29: 375 mg q8h
CrCl <15: not studied
HD: 750 mg ×1 then 150 mg q8h a
Reserve for MDR PSA and ESBL-producing Enterobacteriaceae.
Combine with metronidazole
Glycylcycline
Tigecycline
100 mg ×1 then 50 mg q12h
—
Increase in all-cause mortality observed in meta-analysis of Phase 3 and 4 clinical trials where greatest differences seen with ventilator-associated pneumonia
Fluoroquinolones
Ciprofloxacin
400 mg q12h
CrCl 5–29 and HD: 400 mg q24h a
ADR: tendonitis/tendon rupture, CNS effects, peripheral neuropathy, hepatotoxicity, crystalluria, photosensitivity, QT prolongation. CI: myasthenia gravis, children due to musculoskeletal toxicity
Levofloxacin
750 mg q24h
CrCl 20–49: 750 mg q48h
CrCl 10–19: 750 mg ×1, then 500 mg q48h
HD: 750 mg ×1, then 500 mg q48h a
“
Moxifloxacin
400 mg q24h
—
“
Nitroimidazole
Metronidazole
500 mg q8h
Give post HD on HD days
—
Aminoglycosides
Gentamicin or tobramycin
5–7 mg/kg q24h b
Consult pharmacist for dosing. Goal for once daily dosing: refer to Hartford nomogram d . Use adjusted BW for obese
Amikacin
15–20 mg/kg q24h b
“
Monobactam
Aztreonam
1–2 g q6–8h
CrCl 10–30: 0.5–1 g q6–8h
CrCl <10: 250–500 mg q6–8h
HD: 1–2 g LD, then 250–500 mg q6–8h a
Possible cross-sensitivity between aztreonam and ceftazidime (<5%); see comment on ceftazidime
Glycopeptide
Vancomycin
15–20 mg/kg q8–12h
CrCl 15–50: 750–1500 mg q24h
Max: 2 g/dose
CrCl <15: 750–1500 mg based on level
HD: 500–1000 mg based on level a
Consult pharmacist for dosing
Goal trough: 10–15 mcg/mL (15–20 mcg/mL if visceral abscesses)
Use actual BW for obese
Notes:
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Surgical management is critical in most intra-abdominal infections
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4–5 days is the recommended duration who have adequate source control; longer duration is appropriate if inadequate or uncertain source control
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Empiric antifungal may be considered for upper gastrointestinal perforations, recurrent bowel perforations, surgically treated pancreatitis, heavy colonization with Candida species, or presence of yeast on intra-abdominal cultures
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Candida albicans : Fluconazole IV 800 mg ×1 then 400 mg daily
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Fluconazole-resistant Candida species:
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Anidulafungin IV 200 mg ×1 then 100 mg daily
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Caspofungin IV 70 mg ×1 then 50 mg daily
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Micafungin IV 100 mg daily
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Antienterococcal therapy: consider in postoperative infection, those who have previously received cephalosporins or other antimicrobial agents selecting for Enterococcus species, immunocompromised patients, and those with valvular heart disease or prosthetic intravascular materials
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Anti-MRSA therapy: consider in patients with MRSA or MDRO risk factors (advanced age, comorbid medical conditions, previous hospitalization/surgery, recent antibiotic agents)
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