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  • imageMost intra-abdominal infections are caused by a defect in the gastrointestinal (GI) tract and best treated by surgical drainage, resection, and/or repair.

  • imagePrimary peritonitis is generally caused by a single organism (Staphylococcus aureus in patients undergoing chronic ambulatory peritoneal dialysis [CAPD] or Escherichia coli in patients with cirrhosis).

  • imageSecondary peritonitis is usually caused by a mixture of bacteria, including enteric gram-negative bacilli and anaerobes, which enhance the pathogenic potential of the bacteria.

  • imageFor peritonitis, early and effective IV fluid resuscitation and electrolyte replacement therapy are essential. A common cause of early death is tissue hypoperfusion precipitated by inadequate intravascular volume.

  • imageTreatment is generally initiated on a “presumptive” or empirical basis and should be based on the likely pathogen(s), local resistance patterns, and severity of illness.

  • imageAntimicrobial regimens for secondary peritonitis, determined by the severity of illness and microbiology data, include: (a) third-generation cephalosporin (ceftriaxone) with metronidazole, (b) piperacillin/tazobactam, (c) a carbapenem (imipenem, meropenem, doripenem, or ertapenem), or (d) a quinolone (levofloxacin or ciprofloxacin) plus metronidazole or moxifloxacin alone.

  • imageTreatment of patients with peritoneal dialysis-associated peritonitis should include an antistaphylococcal antimicrobial, such as a first-generation cephalosporin (cefazolin) or vancomycin, as well as an agent with significant gram-negative bacterial activity such as a third-generation cephalosporin or aminoglycoside; intraperitoneal administration is preferred.

  • imageThe duration of antimicrobial treatment should be 4 days after achievement of source control for most secondary peritonitis infections.

  • imagePatients treated for intra-abdominal infections should be assessed for the occurrence of drug-related adverse effects, particularly hypersensitivity reactions (β-lactam antimicrobials), diarrhea (most agents), fungal infections (most agents), and nephrotoxicity (aminoglycosides).



Activity 1:

Answer the questions for the case below on the basis of the information contained within the chapter and develop a treatment plan following the patient care process.

Case: A 59-year-old woman with history of cirrhosis secondary to alcohol abuse is admitted from an outside hospital for altered mental status and concern for hepatic encephalopathy. The patient lives at home, and the day before admission, the patient told her spouse that her stomach was hurting. The spouse expresses concern that the patient was not receiving lactulose for the past 1.5 weeks and missed her recent liver clinic appointment. The patient was initially admitted for less than 24 hours to an outside hospital and received unknown antibiotics before transfer to the current hospital. On exam, the patient is drowsy and not very responsive to questions. Patient appears jaundiced and is complaining of abdominal pain. No nausea, vomiting, or shortness of breath is observed.

Home medications:

Folic acid 1 mg orally every day

Lactulose 10 g orally twice a day

Magnesium oxide 400 mg orally twice a day

Pantoprazole 40 mg orally every day

Potassium chloride 20 mEq orally twice a day

Hydrochlorothiazide 25 mg orally every day

Spironolactone 25 mg orally every day


Pertinent Labs:

Total bilirubin 11.5 mg/dL (197 µmol/L)

Direct bilirubin ...

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