Internal Medicine Clerkship Case Discussions ______

Pneumonia Faculty Answer Guide

Objectives:

1. Define and describe the epidemiology, pathophysiology, symptoms, signs, and typical clinical course of community-acquired, nosocomial, aspiration pneumonia, and pneumonia in the immunocompromised host. 2. Define and describe the conceptualization of “typical” and “atypical” pneumonia and its limitations. 3. Define and describe common pneumonia pathogens (viral, bacterial, mycobacterial, and fungal) in immunocompetent and immunocompromised hosts. 4. Identify patients who are at risk for impaired immunity. 5. Define and describe indications for hospitalization and ICU admission of a patient with pneumonia. 6. Define and describe the antimicrobial treatments (e.g. antiviral, antibacterial, antimycobacterial, and antifungal) for community-acquired, nosocomial, aspiration pneumonia, and pneumonia in the immunocompromised host. 7. Define and describe the implications of antimicrobial resistance. 8. Define and describe the indications for and efficacy of influenza and pneumococcal vaccinations. 9. Recognize bronchial breath sounds, rales (crackles), rhonchi, wheezes, signs of pulmonary consolidation, and pleural effusion on physical exam. 10. Recommend when to order diagnostic laboratory tests, including complete blood counts, sputum gram stain and culture, blood cultures, and pleural effusion analysis, and how to recommend treatment based on these interpretations.

Clinical Case:

You are on call for the general medicine service, and you are called to the ER to see an 80-year-old female. Her daughter states that she has had the flu. The last two days she has refused to eat, and this evening she appears more confused.

Her past medical history includes CHF, type II diabetes, and mild dementia. Medications include furosemide 20mg per day, digoxin 0.125mg per day, enalapril 2.5mg per day, and glipizide 2.5mg per day. She has no allergies. You are unable to obtain a review of systems from the patient, and her family history is noncontributory. Her sugars (per daughter) have been elevated at 200-300 for the last three days.

Physical examination: Vitals: temperature 35.6 C, respirations 34, and blood pressure 100/50, Oxygen saturation is 87% on room air

General: awake but moaning HEENT: bilateral cataracts, equal and reactive pupils, TMs are normal, mouth is dry, and she has an absent gag reflex

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Neck: supple without enlarged lymph nodes or enlargement of the thyroid Cardiovascular: neck veins are flat at 45 degrees elevation, regular rate and rhythm, PMI is displaced laterally, no murmur Respiratory: decreased breath sounds at the right base with crackles Abdomen: soft and scaphoid with hypoactive bowel sounds Extremities: 2+ edema with chronic venous stasis changes, no cyanosis Neuro: no focal deficits, mini mental status examination score is 6.

Laboratory data: WBC 12,000 Hbg 11 Hct 32 Platelets 250

Differential: 60% segmented neutrophils 20% bands 10% lymphocytes 10% monocytes

Normal electrolytes BUN 30, CR 1.3 Glucose 280 Normal LFTs

Normal UA

Radiologic data: The CXR shows a right lower lobe infiltrate and is depicted below:

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Questions:

1. Does this patient have pneumonia?

Yes, this patient most likely has pneumonia.

2. What are the generally accepted criteria for a diagnosis of pneumonia?

Pneumonia should be considered in the face of a new infiltrate on CXR and some of the following: fever or hypothermia, new cough with or without sputum production, change in sputum color in patient with chronic cough, or dyspnea. Notably, however, even if the CXR is negative but the clinical history and findings support a diagnosis of pneumonia a CT chest should be obtained. Physical findings include altered breath sounds and/or localized rales. Laboratory findings often include leukocytosis. Symptoms may be subtle in the elderly. Non-infectious mimics should also be considered, especially if the patient does not improve (i.e., PE, CHF, BOOP, carcinoma or lymphoma).

3. Describe the different types of pneumonia including community-acquired, nosocomial, and aspiration pneumonia.

Community-acquired pneumonia is an infection of the lungs acquired outside the hospital setting. Nosocomial pneumonia includes both hospital-acquired pneumonia, which is a pneumonia acquired at 48 hours or more after hospital, and ventilator-associated pneumonia, which is a pneumonia acquired at 48 hours or more after being intubated. Note that health-care associated pneumonia is a term that is no longer used; it was previously used to describe a pneumonia that was acquired in a health care facility like a nursing home or dialysis center, but it is no longer used because it was an overly sensitive distinction and led to significant overuse of broad-spectrum antibiotics. Aspiration pneumonia is acquired following the aspiration of fluids or secretions from the oral cavity or nasopharynx.

4. Differentiate the organisms responsible for a typical, atypical, and viral pneumonia.

Typical pneumonias are most commonly caused by S. pneumonia, but may also be caused by H. influenza. Moraxella catarrhalis, S aureus, Group A strep, aerobic gram-negative bacteria, and anaerobes acquired from aspiration.

Atypical pneumonias include those caused by Legionella, mycoplasma, C.pneumonia, C psittaci, and Coxiella burnetti. These are considered “atypical” because they are often resistant to beta lactams and are difficult to culture and are unable to be seen on gram stain.

A number of viruses are associated with viral pneumonias including Influenza A and B, coronaviruses, rhinoviruses, parainfluenza, RSV, Human metapneumo virus, and adenoviruses.

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5. Should this patient be admitted to the hospital? If so, how would decide if she needs admission to a general medicine floor or the ICU? Is she at increased risk for a complicated course?

Patients who are otherwise healthy, have normal vitals, and are felt to have a mild pneumonia can be treated with oral antibiotics as an outpatient. This patient, however, should be admitted. There are several clinical decision tools you can use to help you make this decision including the Pneumonia Severity Index (PSI) or the CURB-65 score (https://www.mdcalc.com/curb-65-score-pneumonia-severity). Her CURB-65 score is 4 which confirms the need to admit her.

She will require admission to the general medicine floor for parenteral antibiotic therapy, oxygen, and observation. Patients who require mechanical ventilation for respiratory failure and those with sepsis requiring vasopressor support should go to the ICU. She is at increased risk because of her age, hypoxia, confusion, increased respiratory rate, and diastolic hypotension. She also has associated comorbidities of CHF, DM and dementia.

6. What further history regarding exposure should be asked of this patient and her family before bed assignment?

All patients with a diagnosis of pneumonia should be questioned regarding possible TB exposure and whether they have an immunocompromised state. Respiratory isolation would then be required.

7. Explain the physical findings present in consolidation versus pleural effusion.

Consolidation of the lung parenchyma increases sound transmission and vibration from the vocal cords, trachea and bronchi to the lung parenchyma. Bronchophony, egophony (E-A) whispered pectoriloquy and increased tactile fremitus should be present. A pleural effusion decreases sound transmission. There will be dullness and decreased breath sounds without any of the above.

8. What further lab studies should be ordered? What is the percentage of patients who have a febrile bacteremia associated with pneumonia? What is the most common early sign of pneumonia in the elderly?

Hospitalized patients require blood cultures, sputum grain stain and culture, urinary antigen test for S. pneumonia, and a urine legionella antigen. A respiratory PCR should also be sent during respiratory virus season from late fall to early spring in the Northern hemisphere.

Most of the time (upwards of 60% in some studies) no specific etiology for pneumonia is determined. At least one-third of the time the patient is unable to produce an adequate sputum. Eleven percent of patients hospitalized with community-acquired pneumonia and 20% of cases of pneumococcal pneumonia have positive blood cultures. Two blood cultures should be obtained from patients hospitalized with community-acquired pneumonia. Pleural fluid evaluation can also be diagnostic if a pleural effusion is present.

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Afebrile bacteremia may occur in up to 20% of cases of pneumonia (especially in the elderly). An increased RR (>30) can indicate pneumonia in the elderly, as can increased confusion.

9. Discuss the sensitivity and specify of the gram stain and the sputum culture.

Expectorated sputum is frequently contaminated by bacteria that colonize the upper airway. Up to 50% of normal adults may carry S. pneumonia in their nasopharynx. Sputum culture is expensive and often not done properly; in fact, under 20% of the time can an adequate sample actually be obtained. Sensitivity at is around 60% and specificity is upwards of 90% if it is a good sample. The patient should be observed to expectorate deeply. Only the purulent portion of sputum should be selected for Gram stain and culture. It should only be examined if it contains >25 PMNS and <10 epithelial cells per low power (not oil-immersion) field (minimal criteria = <25 epithelial cells per low power field). The sensitivity and specificity are similar for gram stain.

10. What four ways do micro-organisms get to the lung, and which of these four is most common?

Respiratory droplet or airborne inhalation (some viruses and tuberculosis); hematogenous (staphylococcus aureus, especially intravenous drug abusers), aspiration and direct inoculation are mechanisms of transmission. Aspiration is the most common mechanism.

11. What is the most common pathogen in community acquired pneumonia? What antibiotic coverage might you suggest initially?

Streptococcus pneumonia is the most common cause of community acquired pneumonia in which a pathogen is identified, i.e., 40-60% of cases. Up to 35% of respiratory isolates of S. pneumonia are resistant to penicillin. If patient is not at risk for MRSA or pseudomonas, empirical therapy should be beta-lactam (i.e. ceftriaxone) plus a macrolide (i.e. azithromycin) OR a respiratory fluoroquinolone (i.e. levofloxacin or moxifloxacin). If patients are at risk for MRSA, vancomycin or linezolid is typically added to this regimen. If patients are at risk for Pseudomonas, a beta-lactam that covers this (i.e. piperacillin- tazobactam, cefepime, meropenem, etc.) as well as a fluoroquinolone that covers this (i.e. levofloxacin) are used. For penicillin allergic patient, the beta-lactam can be substituted with aztreonam or an aminoglycoside.

12. What pathogens are involved in nosocomial pneumonia and what antibiotic coverage might you suggest?

Nosocomial pneumonia occurs in hospitalized patients whose upper respiratory tracts have been colonized by enteric gram-negative bacilli, Pseudomonas aeruginosa and Staphylococcus aureus. These pathogens may display drug resistance, and the choice of empirical therapy should be guided by institution specific data regarding of multi-drug resistant bacteria. An antibiotic regimen could include piperacillin-tazobactam, cefepime, or levofloxacin. If there are risk factors for a multi-drug resistant organism, then the above

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antibiotics OR meropenem or imipenem should be given in addition to an aminoglycoside AND vancomycin or linezolid. Antibiotics should be de-escalated based on laboratory testing.

13. How would treatment differ if this patient was immunocompromised?

Immunocompromised patients are at high risk for a much larger variety of pathogens including fungal infections, less common viral infections, and parasitic infections. This drug management tends to be very complex and most often specialists are consulted to aid in the diagnosis, empirical treatment, and de-escalation of medication.

14. Once clinically improved, what medications would you discharge her on and for how long?

She should be changed to an oral medication like oral levofloxacin and complete a course of antibiotics for 7 to 10 days. Patients with minimal or no comorbidities and a less severe infection can be treated for 5 to 7 days.

15. When should the patient have a repeat CXR? How long might it take before her CXR is normal?

Patients, especially elderly, may have slow resolution of CXR infiltrates. The patient generally improves before the CXR. Repeat CXR’s should only be done in the hospital if the patient clinically worsens or for follow-up of a pleural effusion. In order to document resolution and exclude underlying disease such as neoplasm, a repeat CXR may be done in the outpatient setting at 7-12 weeks.

16. What care can be given this patient in your outpatient clinic to prevent another pneumonia?

She should be given influenza vaccine yearly. Pneumococcal-23 vaccine should also be given.

References:

Musher D, Thorner A. Community-Acquired Pneumonia. NEJM. 371: 1619-1628. https://www-nejm-org.archer.luhs.org/doi/10.1056/NEJMra1312885

Lanks CW, Musani AI, Hsia DW. Community-acquired Pneumonia and Hospital-acquired pneumonia. Medical Clinics of North America. 103 (3): 487-501. https://www-clinicalkey-com.archer.luhs.org/#!/content/playContent/1-s2.0-S0025712518301731

Harrison’s Principles of Internal Medicine, 20e. Chapter 121: Pneumonia https://accessmedicine-mhmedical- com.archer.luhs.org/content.aspx?sectionid=184041853&bookid=2129&Resultclick=2

Updated 6/28/19 MRE