Review Question - QID 216356

This patient is presenting with a fever, abdominal pain/tenderness, fat stranding, and edema surrounding the colon with a small amount of free air on imaging, which are concerning for colitis/diverticulitis with perforation. An appropriate antibiotic regimen may include ceftriaxone and metronidazole to cover gram-negative and anaerobic organisms.

Intraabdominal infections often present with fever and abdominal pain. Diagnoses may include appendicitis, colitis, diverticulitis, and bowel perforation among many others. In a patient with abdominal pain and focal tenderness, an appropriate initial diagnostic test is a CT scan, which may demonstrate inflammatory changes such as fat stranding or edema. Perforation may be seen on CT as free air, and exam may demonstrate rebound tenderness and rigidity. Antibiotic coverage for intraabdominal infections should target gram-negative and anaerobic pathogens, as these organisms commonly cause infection when there is intraabdominal infection. Regimens that are commonly used include ceftriaxone/metronidazole, ciprofloxacin/metronidazole, piperacillin-tazobactam, or ampicillin-sulbactam. Outpatient regimens that can be administered orally may include ciprofloxacin/metronidazole or amoxicillin-clavulanate though patients should be stable, able to tolerate PO, and perforation should not be present if the patient is to be discharged.

Streate and Morris review the epidemiology, pathophysiology, and treatment of diverticulitis. They note there are many risk factors including obesity, diet, and physical inactivity. They recommend antibiotics for patients with diverticulitis unless the infection is refractory, complicated, or progressing.

Incorrect Answers:
Answer 2: Daptomycin and clindamycin would be inappropriate as daptomycin covers for multi-drug-resistant gram-positives including MRSA and clindamycin covers for anaerobes, gram-positives, and MRSA. There is redundant coverage of MRSA and insufficient coverage of gram-negatives with this regimen.

Answer 3: Linezolid and clindamycin offer dual coverage for gram-positives including MRSA but have insufficient coverage for gram-negatives. It would be an inappropriate regimen for an intra-abdominal infection.

Answer 4: Vancomycin and cefepime is inappropriate because while vancomycin covers for MRSA and cefepime covers for gram-negatives, there is insufficient coverage for anaerobes. This regimen would be appropriate for hospital/ventilator associated pneumonia.

Answer 5: Vancomycin and metronidazole​ cover for gram-positives, MRSA, and anaerobic pathogens; however gram-negative pathogens are not covered with these antibiotics.

Bullet Summary:
Intraabdominal infections require antibiotics that cover for gram-negative and anaerobic organisms.