Community Acquired Pneumonia: The Z-pack may not cut it anymore
A 24 year old male comes into your emergency department complaining of shortness of breath, fevers, and productive cough. He is febrile but doesn’t appear to be in distress. He has crackles in the left lower lung field on exam. Chest X-ray shows a focal consolidation in the left lower lobe. He doesn’t have any medical problems and hasn’t been to the hospital in the past year. You diagnose him with community-acquired pneumonia (CAP) and decide he is an optimal candidate for outpatient treatment. You know he will need a course of antibiotics, but what should you choose?
Community acquired pneumonia is a common diagnosis encountered in the Emergency Department. The IDSA/ATS are set to release a new set of guidelines for CAP treatment in 2018, however for now the latest guidelines are from 2007. The 2007 IDSA/ATS guideline recommends single antibiotic coverage with a macrolide (strong recommendation) or doxycycline (weak recommendation) for uncomplicated cases of CAP that can be treated on an outpatient basis1.
So back to our case, we have a clear-cut case of an uncomplicated patient with pneumonia who can be treated as an outpatient. Sounds like a perfect candidate for macrolide mono-therapy, right? Not quite.
Unfortunately, according to a recent clinical review article, current epidemiologic data shows that macrolide resistance has now risen to above 25% in all regions of the United States 2. In fact in our area (Mid-Atlantic) resistance rates are reported to be 48%2. Azithromycin is among one of the most commonly prescribed antibiotics in the US2, and many prescriptions are for conditions that are most likely viral. The fact that macrolide resistance has climbed so much since the 2007 guidelines should serve as a reminder that antibiotic stewardship is an important consideration in medicine.
Aside from the CAP guidelines, what is the significance of the increasing rates of S. pneumoniae to macrolides? While atypical pathogens are an important consideration in CAP, S. pneumoniae still causes the majority of cases2, and therefore the resistance pattern of S. pneumoniae is significant when choosing an antibiotic.
If not just a macrolide, then what should be the antibiotic choice for this patient? Here are the options based on the 2007 IDSA/ATS guidelines1:
Doxycycline; an option given for mono-therapy, however may be expensive. Additionally, pneumoniae resistance rates to doxycycline across the US average 26.4%2.
Beta-lactam + azithromycin; effective coverage, affordable
Respiratory fluoroquinolone; an option that will certainly cover both pneumoniae and atypicals, however it is more broad spectrum than necessary for CAP and therefore broad use is discouraged to try to prevent resistance2
Beta-lactam + doxycycline
The Bottom Line: We would give this patient a beta-lactam plus azithromycin for his uncomplicated CAP. This option is narrower than a respiratory fluoroquinolone, is cheaper than doxycycline, and additionally avoids the problem of growing S. pneumoniae resistance to doxycycline.
We will keep you updated on the upcoming 2018 IDSA/ATS guidelines!
IDSA/ATS Guidelines for CAP in Adults. CID. 2007:44 (Suppl 2) S27-S72
Volturo, GA and Haran, JP. Macrolide Resistance in Cases of Community-Acquired Bacterial Pneumonia in the Emergency Department. The Journal of Emergency Medicine Sep;55(3):347-353
Case courtesy of Dr Jeremy Jones, https://radiopaedia.org/cases/30652″ rID: 30652