Bacterial Pneumonia Case File

Bacterial Pneumonia Case File

Eugene C. Toy, MD, Barry C. Simon, MD, Terrence H. Liu, MD, MHP, Katrin Y. Takenaka, MD, Adam J. Rosh, MD, MS

Case 36

A 70-year-old woman is transferred from a nursing home to the emergency department (ED) due to fever and shortness of breath. Per her daughter, the patient has had a productive cough for 2 days and became more short of breath and less responsive earlier today. The patient’s past medical history is significant for diabetes mellitus, hypertension, and high cholesterol. Her vital signs include temperature 38.9°C (102.1°F), heart rate 104 beats per minute, blood pressure 130/85 mm Hg, respiratory rate 28 breaths per minute, and room air oxygen saturation 91% (96% with 3-L oxygen by nasal cannula). On examination, she is awake but slow to answer questions. The daughter states that her mother is usually more alert than this. Her skin is dry and warm to touch. Her heart sounds are regular and mildly tachycardic without any S3 or S4. On auscultation, she has rhonchi at the right lung base. She does not have any jugular venous distention, lower extremity edema, or calf tenderness.

⯈ What is the most likely diagnosis?

⯈ How should this patient be managed?

ANSWER TO CASE: 36

Bacterial Pneumonia

Summary: A 70-year-old woman is sent from a nursing home due to fever, productive cough, and shortness of breath. On examination, she is febrile, mildly tachycardic, tachypneic, and hypoxic on room air. She has rhonchi in the right lung base but does not have any signs of congestive heart failure or a peripheral deep venous thrombosis.

• Most likely diagnosis: Healthcare-associated pneumonia
• Management: Supplemental oxygen, intravenous antibiotics, blood and sputum cultures, and admission

ANALYSIS

Objectives

1. Define community-acquired versus hospital-acquired versus healthcare-associated pneumonia.
2. Describe the various clinical presentations of pneumonia.
3. Learn the management of pneumonia including the best choices for empiric antibiotic administration.

Considerations

This 70-year-old woman presents with history and physical examination findings consistent with pneumonia. Pneumonia is the most common cause of death from infectious disease and the seventh leading cause of death overall in the United States. Clinical presentations and common etiologic organisms vary among different patient populations. Because this patient is a nursing home resident, she is at risk for infection with multidrug-resistant bacteria. Pneumonia may be associated with significant morbidity and mortality, especially among immunocompromised and elderly patients. However, prompt initiation of therapy can result in improved patient outcomes. Treatment includes appropriate empiric antibiotics, disease assessment, and respiratory support.

Approach To:

Bacterial Pneumonia

DEFINITIONS

COMMUNITY-ACQUIRED PNEUMONIA (CAP): Pneumonia that occurs in a patient living in the general population or community.

HOSPITAL-ACQUIRED PNEUMONIA (HAP): Pneumonia that arises 48 hours or more after hospital admission. HAP includes ventilator-associated pneumonia (VAP; infection which develops more than 48 to 72 hours after intubation).

HEALTHCARE-ASSOCIATED PNEUMONIA (HCAP): Pneumonia that occurs in a patient with substantial healthcare contact (intravenous antibiotics, chemotherapy, or wound care within the past 30 days; nursing home or long-term care facility resident; hospitalization for 2 or more days within the past 90 days; hemodialysis).

CLINICAL APPROACH

Pneumonia is caused by aspiration or inhalation of pathogenic organisms into the lungs or less commonly by hematogenous spread. Thus patients with impaired host defenses (mucociliary clearance or overall immune system) and those with an increased risk of bacteremia or aspiration are at higher risk for developing pneumonia. These higher-risk patients include the elderly, smokers, those with an impaired gag reflex, and HIV-positive patients. Viral respiratory infections can also lead to the development of a superimposed bacterial pneumonia.

The most common causes of CAP are Streptococcus pneumoniae, Haemophilus influenzae, Legionella, Mycoplasma, and Chlamydia. HAP and HCAP are most commonly due to aerobic gram-negative bacilli such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Acinetobacter. Aspiration pneumonias are often polymicrobial, including anaerobic organisms such as Peptostreptococcus, Bacteroides, and Fusobacterium. Immunocompromised patients are at risk for infection with uncommon bacterial, fungal, and viral pathogens (eg, Aspergillus, cytomegalovirus, tuberculosis, Pneumocystis jiroveci). Although the specific etiologic organism cannot be identified with certainty without serologic or microbiologic confirmation, historical information may help narrow the list of likely pathogens based on clinical symptomatology and risk factors for specific infections (Table 36–1).

The typical presentation of bacterial pneumonia includes fever, productive cough with purulent sputum, dyspnea, and pleuritic chest pain. However, patients at the extremes of age may have minimal or no respiratory symptoms. Infants may be brought to the ED for fever, irritability, or respiratory distress. The elderly may present with altered mental status, a decline in baseline function, or sepsis. Patients with impaired immune systems may also present atypically.

The physical examination may reveal fever, tachypnea, tachycardia, or hypoxia. Severe illness may be heralded by severe respiratory distress, marked hypoxia, cyanosis, altered mental status, or hypotension. On auscultation, wheezes, rhonchi, rales,

or bronchial breath sounds may be appreciated. Decreased breath sounds and dullness to percussion suggest the presence of a pleural effusion. Patients at the extremes of age and those who are immunosuppressed may have atypical examination findings. For example, the elderly are often afebrile (or even hypothermic). In these patients, tachypnea may be the most sensitive sign of pneumonia

A chest x-ray is an important diagnostic tool in patients with suspected pneumonia as pulmonary infiltrates will confirm the diagnosis. In some cases, a patient with an initial negative chest radiograph may have infiltrates that “blossom” after rehydration or that are visualized using other types of imaging (eg, computed tomography is more sensitive than plain x-ray). The radiographic appearance of the infiltrates may suggest (but not definitively identify) a possible etiologic organism.

For example, lobar consolidation is typical of Streptococcus pneumoniae or Klebsiella. Staphylococcus aureus, Pseudomonas, and Haemophilus influenzae typically cause multilobar disease. Patchy infiltrates are consistent with Legionella, Mycoplasma, and chlamydial infection. Aspiration pneumonias usually result in infiltrates in dependent areas of the lungs (posterior segment of upper lobe or superior segment of lower lobe). Cavitary lesions, pleural effusions, and pneumatoceles may also be seen with bacterial pneumonias. Immunocompromised patients are especially likely to have atypical radiographic findings (eg, more diffuse or multilobar infiltrates).

Treatment

The initial management of patients with pneumonia includes assessment and, if needed, cardiopulmonary stabilization which may require supplemental oxygen or intubation for patients with severe respiratory distress or respiratory failure.

Antibiotics should be initiated promptly in order to decrease mortality and improve patient outcome. Antibiotics are usually chosen based on the most likely pathogens as determined by assessment of risk factors, clinical presentation (including severity of symptoms and presence of sepsis), and radiographic findings. Healthy patients without any use of antimicrobials in the past 3 months with presumed CAP are best treated with a macrolide (azithromycin). Patients with comorbid diseases or recent antimicrobial use should receive a respiratory fluoroquinolone (levofloxacin) or a β-lactam (cefpodoxime) plus a macrolide as a reasonable alternative. Patients admitted to the ICU require antibiotics that cover a broader range of organisms. A β-lactam (ceftazidime) plus either azithromycin or a fluoroquinolone may be used. If Pseudomonas or community-acquired methicillin- resistant Staphylococcus aureus (MRSA) infection is suspected, additional antimicrobial coverage is required. If concern for aspiration pneumonia consider anaerobic coverage such as clindamycin.

Patients with concern for HAP or HCAP who are at a risk for multidrugresistant pathogens should receive a 3-drug combination therapy: (1) antipseudomonal cephalosporin (cefepime, ceftazidime), antipseudomonal carbapenem (imipenem or meropenem), or piperacillin-tazobactam; (2) antipseudomonal fluoroquinolone (ciprofloxacin or levofloxacin); and (3) anti-MRSA coverage (linezolid or vancomycin).

Those without risk factors for multi-drug–resistant (MDR) organisms may be treated with a single agent: ceftriaxone, ampicillin/sulbactam, ciprofloxacin, moxifloxacin, levofloxacin, or ertapenem.

Disposition

Factors to be considered include patient’s age and comorbidities, physical examination and diagnostic findings, ability to tolerate oral medications, social situation, and ability to obtain close follow-up. Obviously, any patient with unstable vital signs, respiratory distress, hypoxia, severe infection, or intractable vomiting requires a hospital stay.

COMPREHENSION QUESTIONS

36.1 A 55-year-old man with a history of alcoholism complains of a month of subjective fevers, productive cough with greenish sputum tinged with blood. Examination reveals poor dentition with halitosis, coarse breath sounds, and clubbing of his fingers. On chest x-ray, there is a 2-cm cavitary lesion with an air-fluid level in the right lower lobe. Which of the following is the most appropriate treatment?

A. Isolate the patient and initiate antituberculosis treatment.

B. Start intravenous clindamycin.

D. Schedule a bronchoscopy.

E. Discharge with oral amoxicillin-clavulanate.

36.2 A 25-year-old woman with no past medical history presents with fever and productive cough. Her vital signs include temperature 38.8°C (101.9°F), heart rate 115 beats per minute, respirations 20 breaths per minute, blood pressure 115/89 mm Hg, and pulse oximetry 97% on room air. On examination, rhonchi are present in the right lung field. Chest x-ray shows a right middle lobe infiltrate. Which of the following should her treatment include?

A. Admission for intravenous ceftriaxone and vancomycin

B. Admission for intravenous ceftriaxone and azithromycin

C. Outpatient treatment with oral azithromycin

D. Outpatient treatment with oral amoxicillin

36.3 A 65-year-old smoker with past medical history of chronic obstructive pulmonary disease and diabetes presents with productive cough, chills, and pleuritic chest pain. His vital signs include temperature 38.9°C (102.1°F), heart rate 110 beats per minute, blood pressure 140/89 mm Hg, respiratory rate 24 breaths per minute, and pulse oximetry 92% on room air. On examination, he has a barrel chest with diffuse wheezes bilaterally. His chest x-ray reveals a left-lower-lobe infiltrate and pleural effusion. Which of the following is the best treatment?

A. Outpatient treatment with azithromycin

B. Outpatient treatment with levofloxacin

C. Inpatient treatment with ceftriaxone, azithromycin, and vancomycin

D. Inpatient treatment with ceftriaxone and azithromycin

36.4 An 89-year-old was brought by ambulance from a nursing home for fever and cough. His vital signs include temperature 39.9°C (103.9°F), heart rate 120 beats per minute, blood pressure 89/69 mm Hg, respiratory rate 36 breaths per minute, and pulse oximetry 88% on a nonrebreather face mask. He is clammy and lethargic. He has coarse breath sounds bilaterally although decreased on the left. Which of the following is the most appropriate initial intervention?

A. Administer intravenous antibiotics

B. Draw blood cultures

C. Intubation

D. Obtain a chest x-ray

ANSWERS

36.1 B. The history of alcoholism, presence of periodontal disease, duration of illness, symptoms and signs, and radiographic findings suggest an anaerobic source. Clindamycin provides the appropriate antimicrobial coverage.

36.2 C. This is a healthy individual with CAP who can be treated as an outpatient with an oral macrolide. She has no risk factors for drug-resistant Streptococcus pneumonia nor any indications for admission.

36.3 D. This patient is a candidate for inpatient treatment due to his comorbidities and abnormal vital signs. However, he does not appear to require ICU admission. Thus, ceftriaxone and azithromycin are the best options of those listed.

36.4 C. Although these are all appropriate interventions, this patient has significant hypoxia and respiratory distress despite noninvasive supplemental oxygen administration. Thus intubation is required.

CLINICAL PEARLS

⯈ Historical information may help narrow the list of likely pathogens based on clinical symptomatology and risk factors for specific infections.

⯈ Patients at the extremes of age and those immunocompromised may present atypically (clinically as well as radiographically).

⯈ The chest x-ray is usually the most important diagnostic study in patients with suspected pneumonia.

⯈ Empiric antibiotics are chosen based on the most likely pathogens (as determined by assessment of risk factors, clinical presentation, and radiographic findings).

⯈ Factors to be considered when determining need for admission include the patient’s age and comorbidities, physical examination and diagnostic findings, ability to tolerate oral medications, social situation, and ability to obtain close follow-up.

References

American Thoracic Society, Infectious Diseases Society of America. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171:399-416. 

File TM. Community-acquired pneumonia. Lancet. 2003;362:1991-2001. 

Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis. 2007;44:S27-S72. 

Metlay JP, Kapoor WN, Fine MJ. Does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination. JAMA. 1997;278:1440-1445. 

Moran GJ, Talan DA. Pneumonia. In: JA Marx, RS Hockberger, RM Walls eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. Philadelphia, PA: Mosby/Elsevier; 2010. 

Niederman MS, Mandell LA, Anzueto A, et al. Guidelines for the management of adults with community- acquired pneumonia: diagnosis, assessment of severity, antimicrobial therapy, and prevention. Am J Respir Crit Care Med. 2001;163:1730-1754. 

Read RC. Evidence-based medicine: empiric antibiotic therapy in community-acquired pneumonia. J Infect. 1999;39:171-178.

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