A 55 year-old male reports to his primary care physician complaining of a headache, fever and a dry cough for the past 3 days. The patient admits to being a pack a day smoker for the past 35 years, and although he has tried to quit, he has never been successful.A chest X-ray shows small unilateral infiltrate in the left lower lobe, What antibiotic would be the most appropriate in this situation?
Amoxicillin
Azithromycin
Ceftriaxone
Cephalexin
Vancomycin
Correct answer
Azithromycin
Feedback
correct answer: B
This patient is most likely suffering from Legionnaire’s Disease which is an infection with the bacteria Legionella in the spectrum on atypical pneumonias. Legionnaire’s is more common in smokers or people who are immune suppressed. Often there is a history of a person being near aerosolized water (air conditioning etc) but it is a bacteria that colonizes in common places, so this history is not necessary. More common in Legionnaire’s in comparison to other pneumonias is that the patient often has hyponatremia (as above). Therefore the best treatment for an atypical pneumonia is a macrolide like azithromycin (option B). A fluoroquinolone is also acceptable.
Amoxicillin (A), ceftriaxone © and cephalexin (D) are part of the beta-lactam group, but they do not have much activity against atypical pneumonias.
Vancomycin (E) is useful against MRSA and other gram positive bacteria; however, there is no evidence that this patient is suffering from MRSA and therefore, there is no need to use it.