TW, a 53 year old male with no significant past medical history, presents to the ED complaining of shortness of breath, chest pain, and general malaise. Upon further examination he is found to be febrile with leukocytosis, and a chest X-ray reveals bilateral consolidation of the lower lung lobes.
Vitals:
Temp: 101.8 F
BP: 101/73 mmHg
HR: 106 bpm
RR: 22 breaths per minute
SpO2: 87% (currently receiving 2L O2 via nasal cannula)
Labs:
WBC: 18,000 cells/μL
SCr: 1.1 mg/dL
CrCl: 81 mL/min
Allergies: Macrolides (anaphylaxis)
Based on these findings, TW has been diagnosed with community-acquired pneumonia (CAP) and admitted to the medical ward for treatment. What would be an appropriate empiric treatment of CAP for this patient?
A. Ciprofloxacin 400 mg IV BID
B. Levofloxacin 750 mg IV daily
C. Ceftriaxone 2 gm IV daily + azithromycin 500 mg PO daily
D. Cefepime 2 gm IV q8h
Answer with rationale:
Pneumonia is a lower respiratory tract infection involving the alveoli. When the pathogen reaches the alveoli, it triggers an immune response with the release of inflammatory mediators which causes pus to fill the alveoli. The alveoli are responsible for gas exchange, so when fluid fills the alveoli, it impairs oxygenation.
Three components are considered when making a pneumonia diagnosis: signs and symptoms, imaging, and rapid diagnostic results/cultures (if taken and positive). Potential signs and symptoms of pneumonia include dyspnea, cough, pleuritic chest pain, tachypnea, fever, leukocytosis, hypoxia, infiltrates on chest X-ray, etc.
CAP, or sometimes termed Community-acquired bacterial pneumonia (CABP), is a type of pneumonia that was contracted outside of the hospital or starts to present <48 hours after hospital admission. Common pathogens include Streptococcus pneumoniae, Haemophilus influenzae, atypical organisms (Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila), and very frequently respiratory viruses. Rapid diagnostic tools such as respiratory tract PCR testing is very helpful if available and can quickly (within about an hour) detect the most common pathogens if present. Respiratory cultures are often even if taken of poor quality.
Empiric antibiotic treatment regimens depend on site of treatment (outpatient vs. inpatient and if inpatient ICU (severe) vs. non-ICU) and patient specific factors. In the scenario described above, the patient could receive a respiratory fluoroquinolone or a beta-lactam with doxycycline.
Answer A is incorrect. While fluoroquinolones are used to treat CAP, the guidelines specifically recommend respiratory fluoroquinolones (moxifloxacin and levofloxacin) for their excellent coverage against Streptococcus pneumoniae, one of the leading causative pathogens in CAP. Ciprofloxacin is not considered a respiratory fluoroquinolone because it has poor coverage against Streptococcus pneumoniae. Ciprofloxacin would be a reasonable option for hospital-acquired or ventilator-associated pneumonia due to its activity vs. Pseudomonas aeruginosa.
Answer B is correct. Levofloxacin is a respiratory fluoroquinolone which is one of the recommended treatments for inpatient non-ICU CAP given its excellent coverage of Streptococcus pneumoniae and activity against atypicals. Two potential advantages of this regimen are that it is one drug (monotherapy) and due to its high oral bioavailability, this would allow for a likely quick conversion to oral therapy to facilitate discharge.
Answer C is incorrect. This particular regimen is commonly given to treat non-severe CAP in hospitalized patients and would be correct if this patient was not allergic to macrolides. Our patient has a documented severe reaction to macrolides making azithromycin inappropriate. It is important to screen patients for allergies because they can alter treatment decisions.
Answer D is incorrect. Cefepime alone is not an appropriate empiric treatment for CAP since it does not cover atypical organisms, which can commonly cause CAP. Beta-lactams work on bacterial cell walls to exert their effect, and since atypicals do not have cell walls, beta-lactams have no effect on them. For non-severe CAP, hospitalized patients that get a beta-lactam also get either a macrolide or doxycycline. For severe CAP requiring ICU admission, patients may get this same regimen or a beta-lactam plus a respiratory fluoroquinolone.
Brands/generics covered:
Zithromax (azithromycin), Cipro (ciprofloxacin), Levaquin (levofloxacin), Rocephin (ceftriaxone), Maxipime (cefepime), Vibramycin (doxycycline), Avelox (moxifloxacin)
NAPLEX content domains covered:
1.A.1
Domain 1 Foundation Knowledge for Pharmacy Practice- A. Pharmaceutical science principles and concepts 1. Pharmacology
2.A.1
Domain 2 Medication Use Process- A. Prescriptions and medication order interpretation 1. Drug names and therapeutic classes
2.A.2
Domain 2 Medication Use Process- A. Prescriptions and medication order interpretation 2. Indications, usage, and dosing regimens
3.C.
Domain 3 Person-Centered Assessment and Treatment Planning- C. Patient health conditions including special populations and medication-related factors