A Clinical Pathologic Case Presentation With an Approach to Community-Acquired Pneumonia

You're a first year intern and asked to present a clinical pathologic case (CPC). You've got two days. Don't fume just yet.

Follow the template below and you'll be fine. Besides, I've added in italics the clinical aspects of the presented case that typifies the rational approach to a patient with community-acquired pneumonia (CAP). CAP is one of the most common presentations clinicians face but it's mostly not dealt with fairly, since most physicians tend to run overboard while prescribing tests or antibiotics.

CLINICAL PATHOLOGIC CASE #1

A 66-year-old woman presents with chief complaints of fever and a productive cough for the past one week. She is generally healthy and leads a healthy lifestyle. But lately she has been feeling lethargic and has generalized body aches. Temperature is 100 F, blood pressure is 140/80 mm Hg, and pulse is 92/min. Lung auscultation reveals abnormal breath sounds and increased vocal fremitus over the right side of the chest.

CHIEF COMPLAINT/PRESENT ILLNESS:

• 66-year-old female with no known comorbid.
• Fever, cough, and a productive sputum. 
• Recent malaise.
• Local resident. 
• No h/o hospitalization, IV antibiotic use, travel history.

Based on this presentation, the patient's coming with a fever, she has some sort of cough, she's also got this productive sputum coming from the lungs. Based on all these parameters, clearly if we had to say, she's got an infection. That's pretty straightforward. Now the question is, where is the infection? Because she's got that sputum, you can focus and narrow your diagnosis to the lung. The next real question, is it an URTI or a LRTI. When looking at URTI, you can still have some amount of sputum. However, if there's some sort of yellowish, brownish, greenish, purulent, large-volume sputum with high fevers, most of the time it's going to be a LRTI.

REVIEW OF SYSTEMS:

• Fever
• Fatigue
• Cough
• Sputum
• Denies night sweats, weight loss
• Denies chest pain
• Denies wheeze, hemoptysis
• No abdominal symptoms

Review of systems in unremarkable except for the presenting complaints of fever, fatigue, cough, and sputum. She's generally healthy. In order for you to figure out exactly what's going on, you must now do a physical exam, and order some labs and certain forms of radiologic tests.
So let's dive into the physical examination. VITAL SIGNS:

BP: 140/80 mm Hg

Pulse: 92 beats/min
Resp rate: 20/min
Temp: 100 F
98% on RA The patient's tachycardic, and she's tachypneic, with high-grade fevers. She's not in respiratory distress, like she's not desaturating or anything.

PHYSICAL EXAM: GPE: alert, oriented, mildly tachypneic
Respiratory system: Bronchial breath sounds Right LL
                                  Inc vocal & tactile fremitus
                                  No wheeze or crackles
Rest: Normal Respiratory system is the most important part of the physical examination in a patient in which you're suspecting a lung infection. We've narrowed it even further, basically pointed to the right lower lobe based on a good physical examination. And what about the rest of the physical examination? It's completely fine, there's no pedal edema, no abdominal problems, no neurologic problems. We now have a high suspicion of CAP, considering she's coming from a regular home. But you cannot diagnose pneumonia from a physical examination alone, even if you're that good. So you've to order labs.

LABS AND ORDERS: Complete blood count: Hemoglobin/WBC count/Platelet count/Hematocrit= 14.0/11.6/286/42
Basic metabolic panel: BUN/Creatinine/Serum electrolytes=4.5/93/Na=139,K=3.9,Cl=100 Procalcitonin 0.2
Chest X-Ray with right lower lobe consolidation This patient has cough, fever, and a right lower lobe infiltrate on chest x-ray, indicating lobar pneumonia likely due to a community-acquired pathogen e.g., Streptococcus pneumoniae. This patient had an elevated WBC count, but sometimes you can have leukopenia indicative of an infection. She isn't anemic, there's no thrombocytopenia, and the hematocrit's normal. The platelet count becomes relevant later on when I'm going to tell you about a scoring system that is used. Similarly, BUN also belongs to a certain scoring system. If a patient who's got infection is becoming septic, and blood pressure starts to drop, it's going to affect the kidneys adversely, and BUN and creatine start to rise.
The gold standard test to diagnose CAP is actually the simplest of tests, a chest X ray. In most cases when you see an infiltrate on CXR, you've diagnosed a CAP. CAP in otherwise healthy individuals is caused by Streptococcus Pneumoniae, the most common bacterial etiology worldwide. Lobar consolidation is classic.
Now the resident who's treating this patient has certain questions going on in his mind. The question is: when to do a sputum culture, blood culture, and certain fancy tests such as the urine Legionella antigen test, blood tests for Chlamydia or Mycoplasma Pneumoniae, or viral PCRs. That basically depends on where the patient is going to be treated: At home? At the hospital? Going to the ICU? Let's move to assessment and plan.
Therefore, in an attempt to standardize the admission decision process and avoid unnecessary admissions, the current guideline strongly recommends the use of two severity-of-illness and mortality prognosis objective scoring systems - the Pneumonia severity index, or PSI and CURB-65.

CAP: DEFINE SEVERITY/PROGNOSIS:

• CURB 65
  CRB 65

• Pneumonia severity index (PSI) Identifies large proportions of people at lower risk

Curb-65 scoring

In the CURB-65 scoring, C stands for confusion, indicating sickness is getting worse, the patient's disoriented probably because of hypoxia or hypotension. U stands for uremia essentially if the patient becomes septic and blood flow to the kidney decreases, leading to acute renal failure. R is for a respiratory rate>30 /min, if the patient is in respiratory distress. B stands for a systolic BP <90 mm Hg, and finally age>/65 years is taken into account. If the score's 0 or 1, patient can safely be discharged home on empiric antibiotics. 2, gets admitted to the hospital on the general medical floor. If it's a 3 or greater than that, consider sending patient to the ICU or use the other scoring system, PSI. PSI is a very comprehensive index that has high discriminative power in predicting the 30-day mortality as well. If you're suspecting pneumonia in a clinic patient, you use a scoring system similar to CURB-65 without the 'U', CRB-65. You cannot wait for the BUN to determine if the patient needs to go the ER. A CRB score anything other than 0, that is >/1, patient will go to the hospital to the regular medical floor. CAP: TREATMENT-OUTPATIENT SETTING

No comorbidities or risk factors for PSA/MRSA

• Amoxicillin 1 gm TDS or
• Doxycycline 100 mg BD or
• Macrolide Azithromycin day 1: 500 mg QD followed by 250 mg daily
  Clarithromycin 500 mg BD
  Clarithromycin ER 1 gm QD

With comorbidities

• Amoxicillin/clavulanic acid or cephalosporin AND
• Macrolide or doxycycline OR
• Respiratory fluoroquinolone Levofloxacin 750 mg QD
  Moxifloxacin 400 mg QD
  Gemifloxacin 320 mg daily

So you've answered the first big question: where the patient is headed? Questions you need to ask at this point: 1. does the patient have comorbidities? 2. Has the patient been on certain antibiotics in the past 3 months? Specifically enquire about macrolides, doxycycline or fluoroquinolones. Why these antibiotics? Because you're going to treat CAP with these antibiotics and if the patient has comorbidities or there's a history of recent antibiotic use, they are at increased risk of drug-resistant pneumonia. If the answer to both these questions is No, it's simple. You will prescribe amoxicillin or a macrolide or doxycycline. If, however, the patient is headed home and the answer to either is Yes, you will prescribe a macrolide or doxycycline, but combine it with another weapon-that's your beta-lactam antibiotic such as amoxicillin/clavulanate, cefuroxime, or cefotaxime. Or you could do monotherapy with a respiratory fluoroquinolone that works well in the lungs.

CONCLUSION:

Amoxicillin 1 gm TDS WITHOUT obtaining cultures or adding MRSA or Pseudomonas coverage. By this point, we're so sure this patient is headed home on empiric antibiotics. Only in the rare instance of failed outpatient therapy, you then need to think outside the box.

This is the maximum detail a CPC entails. Make sure to check out the next article in my blog as a follow-up to this topic!