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A 44-year-old woman is hospitalized from the emergency department because of left lower lobe pneumonia. Medical history is unremarkable except for recurrent urinary tract infections for which she has received various antibiotics.
Temperature on admission is 39.2 °C (102.5 °F), and intravenous levofloxacin is begun. One day later, her temperature has decreased to 38.1 °C (100.5 °F), and blood cultures obtained in the emergency department are growing Streptococcus pneumoniae with an minimal inhibitory concentration (MIC) for penicillin equal to 1 µg/mL (intermediate-level resistance).
Which of the following is the most appropriate therapy at this time?
A Change to cefuroxime
B Change to vancomycin
C Change to ampicillin“sulbactam
D Change to linezolid
E Continue levofloxacin
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sir itna zaalim qs.
anyway
CCC
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Correct Answer = E)
Key Points
* Penicillin resistance is categorized as either intermediate-level resistance (minimal inhibitory concentration [MIC] between 0.1 and 1 μg/mL) or high-level resistance (MIC >1 μg/mL).
* Organisms that are resistant to penicillin generally remain sensitive to fluoroquinolones and are uniformly sensitive to vancomycin and linezolid.
Penicillin resistance is categorized as either intermediate-level resistance (minimal inhibitory concentration [MIC] for penicillin between 0.1 and 1 μg/mL) or high-level resistance (MIC for penicillin >1 μg/mL). In the United States, more than 40% of patients with Streptococcus pneumoniae infection are infected with strains that have some level of antibiotic resistance. Although organisms that are resistant to penicillin are often associated with in vitro resistance to other antibiotics, these organisms generally remain sensitive to fluoroquinolones and are uniformly sensitive to vancomycin and linezolid.
This patient required hospitalization for community-acquired pneumonia and was appropriately started on intravenous levofloxacin as initial empiric antibiotic therapy. Although she was later found to have bacteremic pneumococcal pneumonia caused by an organism with intermediate-level resistance to penicillin, her fever curve is improving following initiation of levofloxacin, which should be active against this strain. The current therapy should therefore be continued until she fulfills the criteria for changing to oral antibiotic agents. In addition, the presence of bacteremia does not affect either the type or duration of antibiotic therapy.
Although not included in the options, ceftriaxone and cefotaxime are also appropriate for treating pneumococcal pneumonia caused by strains with reduced susceptibility to penicillin if the MIC for either agent is less than 2 μg/mL.
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