| Author | 8 Posts |
Justice
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A 22-year-old man was admitted to the intensive care unit in a comatose state following a motor vehicle accident. Intubation and mechanical ventilation were begun.
After 1 week, he remained comatose and on mechanical ventilation and had also developed fever and purulent sputum. A chest radiograph showed a pulmonary infiltrate. A Gram-stained tracheal aspirate showed many leukocytes and gram-negative bacilli, and culture of the aspirate grew Enterobacter cloacae that was sensitive to third-generation cephalosporins, piperacillin, and
trimethoprim/sulfamethoxazole. Intravenous ceftazidime was begun.
Today, 10 days after starting ceftazidime, the pulmonary infiltrates are less extensive. However, the patient remains febrile. Nurses report no diarrhea. Physical examination findings are unchanged. Blood cultures, urinalysis, and urine culture are negative. Repeat Gram stain of a tracheal aspirate shows many leukocytes and gram-negative bacilli, and repeat culture of the aspirate grows E. cloacae that is now sensitive to trimethoprim/sulfamethoxazole and resistant to all β-lactams except imipenem.
In addition to discontinuing ceftazidime, which of the following should be done next?
A. Start imipenem to complete a 2- to 3-week course of antibiotic therapy
B. Start trimethoprim/sulfamethoxazole to complete a 2- to 3-week course of antibiotic therapy
C. No new antibiotics are required
D. Start oral cefixime to complete a 3-week course of antibiotic therapy
E. Start metronidazole to complete a 3-week course of antibiotic therapy
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| peter90036
Forum Elite
Topics: 28
Posts: 315
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i now got it from that sensitive to penicillin and i picked not penicillin 
will be useful when i'm up for step 3 ... some time in the future, not soon.
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| guangyu
Forum Elite
Topics: 29
Posts: 308
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A
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| Jcala
Forum Junior
Topics: 14
Posts: 59
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A ?
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| Markus2009
Forum Senior
Topics: 9
Posts: 191
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i have no clue...but i will go with a simple drug-------->B
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| aspire
Forum Senior
Topics: 24
Posts: 158
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B? -TMP/Sulfa
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| Justice
Forum Fanatic
Topics: 117
Posts: 2,323
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The correct answer is B
Emergence of a derepressed mutant of Enterobacter cloacae is the most likely cause of this patients second positive tracheal culture. In view of the absence of new or progressive infiltrates on chest radiographs, nosocomial pneumonia due to this derepressed mutant is unlikely. Without an infectious etiology, drug-induced fever on an allergic basis is the most likely cause of his persistent fever. Gram-negative bacillary pneumonia is usually treated for 2 to 3 weeks, so that changing to another antibiotic to which the organism is susceptible is required. Trimethoprim/sulfamethoxazole should therefore be started.
Imipenem should not be given, since it is a β-lactam and may cause a cross-reaction in patients who have an allergic reaction to β-lactams. Cefepime is also a β -lactam and is not active against derepressed mutants. Metronidazole is only active against obligate anaerobes, such as Clostridium difficile. In addition metronidazole is inactive against facultative anaerobes, such asE. cloacae.
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| CocaCola
Forum Guru
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good question!
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