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Chapter 50: Miscellaneous Antimicrobial Agents & Urinary Antiseptics

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Infections caused by gram-negative bacilli have occurred when this cationic surfactant has been used as a skin antiseptic.

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(A) Acetic acid

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(B) Benzalkonium chloride

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(C) Lindane

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(D) Hexachlorophene

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(E) Thimerosal

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Pseudomonas and other gram-negative bacteria have caused infections after the use of cationic surfactants such as benzalkonium and cetylpyridinium chlorides, partly because they form a film on the skin under which microorganisms can survive. In addition, some gram-negative bacilli are able to grow in solutions containing benzalkonium salts. Bacterial growth may also occur in solutions of povidone-iodine. The answer is B.

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A young woman is brought to a hospital emergency department with intense abdominal pain of 2 d duration. The pain has spread to the right lower quadrant and is accompanied by nausea, vomiting, and fever. She arrives at the emergency department with a blood pressure of 85/45, pulse 120/min, and temperature 40°C. Her abdomen has a board-like rigidity with diffuse pain to palpation. Laboratory values include the following: WBC 20,000/μL and creatinine 1.5 mg/dL. After abdominal x-ray films are taken, a preliminary diagnosis of abdominal sepsis is made, possibly resulting from bowel perforation. After appropriate samples are sent to the laboratory for culture, the patient is hospitalized, and antimicrobial therapy is started with intravenous ampicillin and gentamicin.

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Regarding the treatment of this patient, which statement is accurate?

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(A) A drug active against anaerobes should be included in the antimicrobial drug regimen

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(B) Cultures are pointless because this is probably a mixed infection

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(C) Empiric antibiotic therapy of abdominal sepsis should always include a third-generation cephalosporin

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(D) Gram stain of the blood would provide positive identification of the specific organism involved in this infection

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(E) The combination of ampicillin and gentamicin provides good coverage for all likely pathogens

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Abdominal sepsis is commonly a mixed infection; the most likely pathogens are Bacteroides fragilis, Enterobacteriaceae, and Enterococcus faecalis. An antibiotic regimen that includes only ampicillin and gentamicin does not control B fragilis. Empiric treatment in this case should include a drug active against this pathogen (eg, metronidazole, cefoxitin, cefotetan, or clindamycin). The answer is A.

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A young woman is brought to a hospital emergency department with intense abdominal pain of 2 d duration. The pain has spread to the right lower quadrant and is accompanied by nausea, vomiting, ...

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