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Pulmonary Infections in Adults

# 550 Edition | March 2025

Preface

Louis Pasteur first isolated pneumococcus in 1881, and the association between pneumococcus and lobar pneumonia was discovered in 1883.1 In the pre-antibiotic era, treatment options were limited, and mortality from pneumonia was high.2

In the early to mid-1900s, the development of antipneumococcal serum therapy and the antibiotics sulfapyridine and penicillin allowed for effective treatment of bacterial pneumonia. The first pneumococcal vaccine was approved in the United States in 1977, and the first conjugate pneumococcal vaccine was licensed in 2000. With these advances, pneumonia and influenza ranked as the ninth leading cause of death in 2019 (14.9 deaths per 100,000 people), far behind heart disease (163.5 deaths per 100,000 people) and cancer (149.1 deaths per 100,000 people).3 The treatment of pneumonia continues to evolve as bacterial pathogens develop resistance to antibiotics, as patients are treated with more medications that change their response to infections and increase their risk of more unusual infections, and as new medications are developed.

Throughout most of my career, like many office-based family physicians, I have encountered pneumonia occasionally. Although I sometimes lost a patient to a respiratory infection, I generally regarded pneumonia as a treatable condition—far less concerning for my patients than the diabetes, hypertension, and heart disease I managed daily. Then, in March 2020, the world changed.

The COVID-19 pandemic transformed the way we practiced medicine and lived our lives. Most of us experienced profound loss—patients, colleagues, friends, and family. No physician who endured this pandemic will ever underestimate the devastating impact of acute respiratory diseases on our patients, our practices, or the world.

This monograph reviews the diagnosis and management of pulmonary infections in adults, focusing on bacterial infections. Section One focuses on community-acquired pneumonia. Sections Two and Three examine the approach to pneumonia that develops in hospitalized patients and those with immunocompromise. Section Four reviews the evaluation and treatment of lung abscesses and pleural effusions. When you complete this monograph, you will have the information you need to confidently diagnose and treat lung infections in your adult patients.

Ryan D. Kauffman, MD, FAAFP, CCFP, Associate Medical Editor
Family Physician
Erie Shores Family Health Team, Leamington, Ontario, Canada

References

  1. 1.Gierke R, Wodi AP, Kobayashi M, et al. Pneumococcal disease. In: Hall E, Wodi AP, Hamborsky J, eds. Epidemiology and Prevention of Vaccine-Preventable Diseases. 14th ed. Centers for Disease Control and Prevention; 2021.
  2. 2.National Center for Health Statistics. Leading causes of death, 1900-1998. September 17, 2001. Accessed September 1, 2024. https://stacks.cdc.gov/view/cdc/53236
  3. 3.Kochanek KD, Xu J, Arias E. Mortality in the United States, 2019. NCHS Data Brief No 395. 2020. Accessed September 1, 2024. https://www.cdc.gov/nchs/products/databriefs/db395.htm

Thomas M. File Jr, MD, MSc, MACP, FIDSA, FCCP, is a distinguished physician in the Infectious Disease Division at Summa Health in Akron, Ohio, and professor emeritus of internal medicine and master teacher of the Infectious Disease Section at Northeast Ohio Medical University, Rootstown. He is a past board of directors president for the Infectious Diseases Society of America and past president of the National Foundation for Infectious Diseases. He has published more than 250 articles, abstracts, and textbook chapters focusing on the diagnosis, etiology, and treatment of infectious diseases, especially respiratory tract infections. He is editor-in-chief of Infectious Diseases in Clinical Practice.

Julio A. Ramirez, MD, FACP, is director of research activities at the Norton Infectious Diseases Institute, Louisville, Kentucky. Dr. Ramirez’s research activities have received funding from the Centers for Disease Control and Prevention, US Department of Defense, and National Institutes of Health. He has written more than 300 peer-reviewed publications.

Disclosure: It is the policy of the AAFP that all individuals in a position to control CME content disclose any relationships with ineligible companies upon nomination/invitation of participation. Disclosure documents are reviewed for potential relevant financial relationships. If relevant financial relationships are identified, mitigation strategies are agreed to prior to confirmation of participation. Only those participants who had no relevant financial relationships or who agreed to an identified mitigation process prior to their participation were involved in this CME activity. The following individual(s) in a position to control content for this activity have disclosed the following relevant financial relationships: Thomas M. File Jr, MD, disclosed a relationship with Merck & Co., Inc. related to its pneumococcal vaccine, a relationship with HealthTrackRx Molecular related to PCR-based tests, a relationship with Thermo Fisher Scientific Inc. related to PCR-based tests, a relationship with MicroGenDX related to advanced DNA diagnostics, a relationship with Shionogi Inc. related to cefiderocol (Fetroja), and a relationship with Paratek Pharmaceuticals, Inc. related to omadacycline (Nuzyra). Julio Alberto Ramirez, MD, disclosed a financial relationship with Pfizer Inc. related to consulting on its pneumococcal vaccine and a relationship with Dompé as a speaker on the topic of pathophysiology of pneumonia. All relevant financial relationships have been mitigated. All other individuals in a position to control content for this activity have indicated they have no relevant financial relationships to disclose.

  • Select appropriate empiric therapy for patients with community-acquired pneumonia.
  • Evaluate patients with community-acquired pneumonia to identify the causative pathogen.
  • Determine which patients with nosocomial pneumonia have risk factors for antimicrobial resistance.
  • Recommend interventions that can prevent nosocomial pneumonia.
  • Differentiate between pneumonia due to common vs opportunistic pathogens in immunocompromised patients.
  • Determine appropriate empiric therapy for pneumonia possibly related to opportunistic pathogens.
  • Counsel patients with lung abscesses about potential treatments.
  • Determine the etiology of pleural effusion.

Key Practice Recommendations

Sections

Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) is a common and potentially serious illness, particularly in older patients and those with significant comorbidities. Recent evidence indicates diverse communities of microbes reside within the alveoli as part of the lung microbiome and may…

Nosocomial Pneumonia

Nosocomial pneumonia, which includes hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), is associated with high morbidity and mortality. HAP occurs 48 hours or more after admission and may require intubation and mechanical ventilation. VAP occurs more…

Pulmonary Infections in Immunocompromised Patients

Immunocompromised patients with pneumonia can have infection with both common pulmonary pathogens and opportunistic pathogens. A basic microbiological workup should be performed in all immunocompromised patients who are hospitalized and considered for outpatients. The need for…

Lung Abscess and Pleural Effusion

A lung abscess is a cavity with a well-defined wall that develops in the lung due to microbial infection. This most commonly occurs with polymicrobial aerobic and anerobic infections related to aspiration pneumonia. Lung abscess may also be related to necrotizing pneumonia from…

  1. 1.File TM, Ramirez JA. Community-acquired pneumonia. N Engl J Med. 2023;389(7):632-641.
  2. 2.Heffner JE, Brown LK, Barbieri CA. Diagnostic value of tests that discriminate between exudative and transudative pleural effusions. Chest. 1997;111(4):970-980.
  3. 3.Kalil AC, Mertersky ML, Klompas M, et al. 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;63(5):e61-e111.
  4. 4.Klompas M, Branson R, Cawcutt K, et al. Strategies to prevent ventilator-associated pneumonia, ventilator-associated events, and non-ventilator hospital-acquired pneumonia in acute-care hospitals: 2022 update. Infect Control Hosp Epidemiol. 2022;43(6):687-713.
  5. 5.Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67.
  6. 6.Ramirez JA, Chandler TR, Furmanek SP, et al. Community-acquired pneumonia in the immunocompromised host: epidemiology and outcomes. Open Forum Infec Dis. 2023;10(11):ofad565.
  7. 7.Ramirez JA, Musher DM, Evans SE, et al. Treatment of community-acquired pneumonia in immunocompromised adults: a consensus statement regarding initial strategies. Chest. 2020;158(5):1896-911.
  8. 8.Sperling S, Dahl VN, Floe A. Lung abscess: an update on the current knowledge and call for future investigations. Curr Opin Pulm Med. 2024;30(3):220-234.

Disclosure
All editors in a position to control content for this activity, FP Essentials, are required to disclose any relevant financial relationships. View disclosures.