Penicillins
The penicillins are bactericidal antibiotics that work against sensitive organisms at adequate concentrations and inhibit the biosynthesis of cell wall mucopeptide.
Piperacillin and Tazobactam sodium (Zosyn)
Piperacillin is a semisynthetic extended-spectrum penicillin that inhibits bacterial cell wall synthesis by binding to specific penicillin-binding proteins; it is the most effective of the antipseudomonal penicillins.
Tazobactam increases piperacillin activity against S aureus, Klebsiella, Enterobacter, and Serratia species; the greatest increase is in activity against B fragilis. However, it does not increase anti–P aeruginosa activity.
Amoxicillin and clavulanate (Augmentin)
Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins; clavulanate inhibits beta-lactamase producing bacteria. This combination is a good alternative antibiotic for patients allergic or intolerant to the macrolide class. Usually, it is well tolerated, and provides good coverage for most infectious agents. It is not effective against Mycoplasma and Legionella species. The half-life of the oral dosage form is 1-1.3 hours. It has good tissue penetration but does not enter cerebrospinal fluid.
Ticarcillin and clavulanate potassium (Ticar)
This combination of an antipseudomonal penicillin with a beta-lactamase inhibitor provides coverage against most gram-positive and gram-negative organisms, as well as most anaerobes. It inhibits biosynthesis of cell wall mucopeptide and is effective during the stage of active growth.
Ampicillin (Omnipen, Marcillin)
Ampicillin interferes with bacterial cell wall synthesis during active multiplication, causing bactericidal activity against susceptible organisms. Dose adjustments may be necessary in renal failure. Rash should be evaluated carefully to differentiate nonallergic ampicillin rash from hypersensitivity reaction.
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Peritonitis and abdominal sepsis. Diagnostic and therapeutic approach to peritonitis and peritoneal abscess.
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Peritonitis and abdominal sepsis. A 48-year-old man underwent suprapubic laparotomy, right hemicolectomy, and gastroduodenal resection for right colon cancer invading the first portion of the duodenum. After surgery, the patient developed abdominal pain and distention. Computed tomography (CT) scanning was used to confirm an anastomotic dehiscence. Figure A shows a contrast-enhanced scan of the abdomen and pelvis that reveals multiple fluid collections, perihepatic ascites, and mild periportal edema. A collection of fluid containing an air-fluid level is visible anterior to the left lobe of the liver. A second collection is anterior to the splenic flexure of the colon. In figure B, a third fluid collection is present in the inferior aspect of the lesser space and in the transverse mesocolon. Figure C shows the pelvis with a collection of free fluid in the rectovesical pouch.
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Peritonitis and abdominal sepsis. A 78-year-old man was admitted with a history of prior surgery for small bowel obstruction and worsening abdominal pain, distended abdomen, nausea, and obstipation. In figure A, a marked amount of portal venous gas within the liver, mesenteric venous gas, and pneumatosis intestinalis are consistent with ischemic small intestine. The superior mesenteric artery appears patent. The liver has a nodular contour consistent with cirrhosis. In figures B and C, markedly distended loops of small intestine containing fluid and air-fluid levels are consistent with a small bowel obstruction. No focal fluid collections are identified.
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Peritonitis and abdominal sepsis. A 35-year-old man with a history of Crohn disease presented with pain and swelling in the right abdomen. In figure A, a thickened loop of terminal ileum is evident adherent to the right anterior abdominal wall. In figure B, the right anterior abdominal wall is markedly thickened and edematous, with adjacent inflamed terminal ileum. In figure C, a right lower quadrant abdominal wall abscess and enteric fistula are observed and confirmed by the presence of enteral contrast in the abdominal wall.
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Peritonitis and abdominal sepsis. Gram-negative Escherichia coli.
