Community-acquired Pneumonia and Hospital-acquired Pneumonia

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Key points

  • Pneumonia is a common disease that requires a deep understanding of pathophysiology, epidemiology, and pharmacology to properly manage.

  • Diagnostic strategies for pneumonia range from simple to highly complex depending on disease severity and likelihood of altering the empiric antibiotic regimen.

  • Pneumonia management plans are tailored to each individual patient encounter and incorporate knowledge of health care setting, pathogen type, and risk factors for antibiotic resistance.

  • Complications from

Pathophysiology

Pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, and gram-negative bacilli typically enter the lower respiratory tract through aspiration of oropharyngeal secretions. Microaspiration can occur on a regular basis, even in healthy individuals and particularly during sleep, but progression to pneumonia is rare. Progression largely depends on the inoculum of pathogenic bacteria, volume of aspirate, frequency of aspiration, and virulence of aspirated bacteria relative to the host

Epidemiology

Pneumonia remains a leading cause of hospitalization and death worldwide. In 2015, pneumonia was the eighth leading cause of death in the United States,1 the fourth leading cause of death worldwide, and leading cause of death in low-income countries.7 However, the true incidence of CAP is likely underestimated. Patients with mild infections are less likely to seek medical attention and diagnosis may therefore go unrecognized.

Clinical presentation

The classic or typical presentation of pneumonia is characterized by the acute onset of infectious lower respiratory tract symptoms in conjunction with consistent radiographic findings. Fever, cough, pleurisy, dyspnea, and increased sputum production are common symptoms of pneumonia. In many patients, the presentation of pneumonia can be atypical and characterized predominantly by nonrespiratory symptoms such as malaise, myalgia, confusion, and diarrhea. In elderly individuals, this type of

Imaging

Radiographic evidence of parenchymal lung involvement is needed to establish the diagnosis of pneumonia. The radiographic appearance of pneumonia can be highly variable (Fig. 1). Although computed tomography (CT) is the gold standard for detection of pulmonary infiltrates, plain chest radiographs are more frequently obtained, especially in the outpatient setting. Although CT imaging can elucidate more specific findings than plain chest radiography (see Figs. 1D–F), it also exposes patients to

Severity Scores

Severity scoring indices seek to standardize the decision to treat patients with CAP in the outpatient versus inpatient settings by predicting mortality. Determination of disease severity is often the first branch point in the management algorithm for CAP (Fig. 3). The PSI (Pneumonia Severity Index) and CURB-65 (confusion, urea nitrogen, respiratory rate, blood pressure, age ≥ 65 years) scoring systems are the most widely used of these tools. The PSI includes 20 different variables and may be

Complications

Complications of pneumonia frequently occur. Although not all cases of pneumonia require pulmonary consultation, when complicating factors are evident at the time of initial presentation or arise during treatment, consultation with a pulmonary specialist should be considered (Box 1).

Parapneumonic effusions frequently complicate pneumonia. Most of these are sterile inflammatory exudates and do not require a change in management. However, when microorganisms transit into the pleural space, a more

Prevention

For pneumonia prevention, behavioral risk factors such as smoking and alcoholism should be addressed. Vaccines for influenza and S pneumoniae are routinely used in select patient populations. Annual influenza vaccination is recommended in all individuals more than 6 months of age with priority given to older adults, immunocompromised patients, those with medical comorbidities, and health care workers.57

Conjugate (PCV13) and polysaccharide (PPSV23) vaccines against S pneumonia are available.

Outcomes

Mortality from CAP in the ambulatory, inpatient, and ICU settings is approximately 5%, 15%, and 36%, respectively.61 Overall mortality is approximately 10%, with half of the deaths occurring after hospital discharge.62 Gram-negative organisms and S aureus have the highest mortalities.61 Thirty-day readmission rates are between 7% and 18% and result from both recurrent pneumonia as well as exacerbations of preexisting comorbidities.63, 64, 65 Patients who survive beyond 30 days have

Summary

Although pneumonia is a commonly encountered problem in clinical practice, variability in presentation, causative organism, and severity make appropriate diagnosis and treatment extremely challenging. There have been many recent advances in diagnostic techniques such as PCR testing and point-of-care ultrasonography, but recommendations for antimicrobial treatment are largely unchanged in the last decade. Particular attention should be paid to multidrug resistance and development of

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References (66)

  • G.L. Colice et al.

    Medical and surgical treatment of parapneumonic effusions: an evidence-based guideline

    Chest

    (2000)
  • F. Herth et al.

    Endoscopic drainage of lung abscesses: technique and outcome

    Chest

    (2005)
  • M.L. Metersky et al.

    Predictors of in-hospital vs postdischarge mortality in pneumonia

    Chest

    (2012)
  • A. Capelastegui et al.

    Predictors of short-term rehospitalization following discharge of patients hospitalized with community-acquired pneumonia

    Chest

    (2009)
  • A.H. Bruns et al.

    Cause-specific long-term mortality rates in patients recovered from community-acquired pneumonia as compared with the general Dutch population

    Clin Microbiol Infect

    (2011)
  • M. Heron

    Deaths: leading causes for 2015

    Natl Vital Stat Rep

    (2017)
  • L.A. Mandell 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)
  • A.C. Kalil et al.

    Is bacteremic sepsis associated with higher mortality in transplant recipients than in nontransplant patients? A matched case-control propensity-adjusted study

    Clin Infect Dis

    (2015)
  • J.D. Chalmers et al.

    Epidemiology, antibiotic therapy, and clinical outcomes in health care-associated pneumonia: a UK cohort study

    Clin Infect Dis

    (2011)
  • A.C. Kalil et al.

    Executive summary: management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society

    Clin Infect Dis

    (2016)
  • W.M. Scheld

    Developments in the pathogenesis, diagnosis and treatment of nosocomial pneumonia

    Surg Gynecol Obstet

    (1991)
  • M.A. Said et al.

    Estimating the burden of pneumococcal pneumonia among adults: a systematic review and meta-analysis of diagnostic techniques

    PLoS One

    (2013)
  • B. Beović et al.

    Aetiology and clinical presentation of mild community-acquired bacterial pneumonia

    Eur J Clin Microbiol Infect Dis

    (2003)
  • D.J. Weber et al.

    Comparison of hospitalwide surveillance and targeted intensive care unit surveillance of healthcare-associated infections

    Infect Control Hosp Epidemiol

    (2007)
  • F. Arancibia et al.

    Community-acquired pneumonia due to gram-negative bacteria and Pseudomonas aeruginosa: incidence, risk, and prognosis

    Arch Intern Med

    (2002)
  • E. Prina et al.

    Risk factors associated with potentially antibiotic-resistant pathogens in community-acquired pneumonia

    Ann Am Thorac Soc

    (2015)
  • V. Luchsinger et al.

    Community-acquired pneumonia in Chile: the clinical relevance in the detection of viruses and atypical bacteria

    Thorax

    (2013)
  • Centers for Disease Control and Prevention (CDC)

    Bacterial coinfections in lung tissue specimens from fatal cases of 2009 pandemic influenza A (H1N1) - United States, May-August 2009

    MMWR Morb Mortal Wkly Rep

    (2009)
  • A. Torres et al.

    Risk factors for community-acquired pneumonia in adults in Europe: a literature review

    Thorax

    (2013)
  • M. Falguera et al.

    Risk factors and outcome of community-acquired pneumonia due to Gram-negative bacilli

    Respirology

    (2009)
  • R.G. Wunderink

    Slow response times: is it the pneumonia or the physician?

    Crit Care Med

    (2005)
  • R. Zalacain et al.

    Community-acquired pneumonia in the elderly: Spanish multicentre study

    Eur Respir J

    (2003)
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    Disclosure: The authors have no financial conflicts of interest.

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