Community Acquired Pneumonia: an Evaluation of Diagnosis and Treatment by NEJM

The NEJM released an article yesterday addressing a very common clinical problem, Community Acquired Pneumonia, and evaluates the guidelines currently in place and offers recommendations. It starts off with a vignette.

A 67-year-old woman with mild Alzheimer's disease who has a 2-day history of productive cough, fever, and increased confusion is transferred from a nursing home to the emergency department. According to the transfer records, she has had no recent hospitalizations or recent use of antibiotic agents. Her temperature is 38.4°C (101°F), the blood pressure is 145/85 mm Hg, the respiratory rate is 30 breaths per minute, the heart rate is 120 beats per minute, and the oxygen saturation is 91% while she is breathing ambient air. Crackles are heard in both lower lung fields. She is oriented to person only. The white-cell count is 4000 per cubic millimeter, the serum sodium level is 130 mmol per liter, and the blood urea nitrogen is 25 mg per deciliter (9.0 mmol per liter). A radiograph of the chest shows infiltrates in both lower lobes. How and where should this patient be treated?


The World Heath Organization (WHO) estimates that pneumonia is the most common infectious cause of death worldwide and the third most common cause of death overall. Community acquired pneumonia that is severe enough to warrant hospitalization is associated with an increase in mortality as well as increased costs, especially if the patient needs to be admitted to the ICU. Because of the mortality associated with severe community acquired pneumonia and the costs associated with admission, this article focuses on the interventions and guidelines to reduce mortality and costs.


Diagnosis of CAP

 Evidence of infection (fever/chills, leukocytosis), respiratory symptoms (cough, sputum production, SOB, chest pain and abnormal respiratory physical exam) and a new or changed infiltrate on the chest x-ray usually identifies patients with community acquired pneumonia. This diagnosis is not as straight forward in patient who has lung cancer, heart failure or underlying infiltrative lung disease. Atypical presentations, such as confusion, may delay the diagnosis. Human error can play a role as a Radiologist may miss an infiltrate on an x-ray.


Initial Management

 Once CAP is diagnosed, three decisions must be made: what type of antibiotics should be used, what type of testing should be used to determine the cause of the pneumonia and where should the patient be treated (home, inpt or the ICU)?

What type of antibiotics should be used? Appropriate therapy for CAP requires adequate coverage of Streptococcus pneumonia and the atypical bacterial pathogens such as mycoplasma, chlamydia, and legionella. For outpatient treatment, atypical coverage is important and the most appropriate therapy choices are Macrolides, Flouroquinolones and Doxycycline. For patients who will be admitted to the hospital or the ICU, the current recommendations (based on inpatient data that shows a decrease in mortality and length of hospital stay) advise first-line treatment with a flouroquinoline that is effective against the respiratory system (Levofloxacin or Moxifloxacin) or a combination of a second or third generation of a cephalosporin plus a macrolide. It is recommended that the timing of the first antibiotic be given within 6 hours of the initial presentation. It was shown that mortality decreased if the antibiotic was given in the first 4 hours of presentation but this increased the inappropriate use of antibiotics and the side effects such as C. Diff. An exception is made for patients who present with shock and states that the antibiotics should be given within 1 hour of hypotension. The duration of antibiotic treatment is 5-7 days and there has been no evidence of decreased mortality in extended the therapy beyond 7 days.  Health care acquired pneumonia (HAP) is a different beast and you need to treat with antibiotics that will cover MRSA and Pseudomonas Aeruginosa.  The criteria to diagnose HAP is detailed below.

Hospitalization for ≥2 days during the previous 90 days

Residence in a nursing home or extended-care facility

Long-term use of infusion therapy at home, including antibiotics

Hemodialysis during the previous 30 days

Home wound care

Family member with multidrug-resistant pathogen

Immunosuppressive disease or therapy

There is a strain of MRSA that is increasing in the previously healthy population and causing community acquired pneumonia and produces an exotoxin. The article recommends treatment against the MRSA (vancomycin) plus treatment against the exotoxin (linezolid or clindamycin).

Diagnostic testing

Blood culture – strongly recommended in CAP if the patient is hypotensive or has been transferred from the general medical floor to the ICU, in HAP, if the patient has cirrhosis or asplenia. The antibiotic treatment will change depending on the blood culture result.

Respiratory tract culture – strongly recommended if the aspirate in an intubated patient or a productive cough in a non-intubated patient. Antibiotic therapy may change if the sputum culture warrants.
Influenza test during influenza season – recommended in all cases (CAP and HAP) and if tested positive add or continue Oseltamivir.

Test for Urinary Pneumococcal Antigen – Recommended in both CAP and HAP

Test for Urinary Legionella Antigen – Recommended in both CAP, HAP (if the patient comes from a nursing home) and if the patient has travelled recently

Pleural-Fluid Culture – Strongly recommended in both CAP and HAP

Site of Care

Currently, the decision to admit to the medical floor can be objectively determined by the CURB-65 score which assigns 1 point for each. A score of 3 or greater indicates hospitalization. I have seen physicians use this but not stick by it which is understandable because not included in the score are results such as low O2 saturation or if they know that the patient will be non-compliant with medication as an outpatient.

C – Confusion
U – Uremia BUN > 20mg/deciliter
R – Respiratory Rate > 30 breaths/min
B – Blood Pressure Systolic < 90 or diastolic < 60
65 – Age > 65 years

ICU admission may be considered if the patient has  3 or more of the nine criteria: hypotension, tachypnea, confusion, elevated BUN, multilobar infiltrates seen on chest x ray, hypoxemia, thrombocytopenia, hypothermia, leukopenia.
The article states that if these criteria are rigidly followed, more inappropriate ICU admissions occur. The article recommends that much of the decision making about placement will occur in the ED and patients who fit the criteria for ICU admission should be first given the following interventions such as fluid resuscitation, antibiotics, inhalers/bronchodilator treatment and measurement of ABG and then reassess the patient’s disposition.

So, the woman in the vignette at the beginning of my post has a CURB-65 score of 4 (confusion, respiratory rate, BUN and age). She has four minor criteria (confusion, resp rate, BUN and multilobar infiltrates) that would suggest she should be admitted to the ICU but first, she would benefit from further evaluation in the ED such as fluid resuscitation and measuring ABG. She is a nursing home resident which places at risk for HAP however, she does not have any risk factors for MDR so it would be appropriate to treat for severe CAP with a macrolide and a second or third generation cephalosporin. Blood cultures would not be necessary and I would get sputum cultures because he cough was productive (the article doesn't recommend this?). The article does not mention whether to do urine antigen testing but I would based on their previous recommendations. If it was influenza season, I would do an influenza test on the patient.