Although the treatment of community acquired pneumonia (CAP) is bread-and-butter emergency medicine, several guidelines and landmark studies have called for fairly big changes in clinical practice.^1–4 Two recommendations deserve particular attention. Importantly, recommendations include significantly narrowing the use of antibiotics that cover methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (P. aeruginosa), even in severe pneumonia. That’s right, empiric vancomycin and piperacillin-tazobactam or cefepime only applies to a subset of “high risk” patients or those with severe pneumonia. Additionally, select patients with CAP requiring ventilatory support may benefit from hydrocortisone.

Antibiotics

For years, antibiotic selection has been largely dependent on the presumed location or source of the development of the pneumonia. Categories of pneumonia have included CAP, hospital-acquired (HAP), ventilator-associated (VAP), and, beginning in 2005, health care-acquired (HCAP). Although these categories were created to help predict risk for multi-drug resistance (MDR), data demonstrated that patients who fell into the HCAP group did not have higher prevalence of antibiotic-resistant pathogens. As a result, the 2019 guidelines from the Infectious Disease Society of America (IDSA) significantly rein in those patients who should receive empiric coverage for MRSA or P. aeruginosa. The recommendations can be seen across categories, but notably empiric treatment with the beloved combination of vancomycin and piperacillin-tazobactam (or cefepime) is not recommended in CAP, even severe CAP, unless very specific risk factors are present.

For example, inpatients with a history of prior respiratory isolation of MRSA or P. aeruginosa should receive the addition of antimicrobial coverage targeted to the prior isolate, but not necessarily targeted to both MRSA and P. aeruginosa. Additionally, those with a hospitalization and receipt of parenteral antibiotics in the last 90 days should receive extended coverage for MRSA and/or P. aeruginosa only if they have specific locally identified risk factors for those organisms.

Lastly, given widespread macrolide resistance in the U.S., it’s unlikely that many clinicians are treating CAP with macrolide monotherapy. However, these guidelines also serve as a reminder that if you are routinely treating CAP with macrolide monotherapy and you are not certain that local resistance levels are less than 25 percent, it is time to choose a different antibiotic.

Corticosteroid Use

Historically, the administration of corticosteroids in patients hospitalized with pneumonia has been controversial. In 2017, the Society of Critical Care Medicine (SCCM) and the European Society of Intensive Care Medicine (ESICM) stated, “We suggest the use of corticosteroids for 5–7 days at a daily dose <400 mg intravenous hydrocortisone or equivalent in hospitalized patients with CAP,” citing moderate-quality evidence.²