Atypical pneumonia

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Última revisión: 26 Nov 2025

Última actualización: 10 Sep 2024

Atypical pneumonia (non-COVID-19) is a community-acquired infection often seen in young adults or children living in close proximity.

Diagnosis is mostly clinical. Molecular-based diagnosis of nasopharyngeal swabs, throat swabs or sputum can be performed. Serology can be used to confirm the diagnosis.

Treatment is often outpatient based with a macrolide antibiotic or doxycycline.

Extrapulmonary manifestations may occur, especially in Mycoplasma pneumoniae infections.

Definición

Atypical bacterial pneumonia is caused by atypical organisms that are difficult to detect on Gram stain and difficult to culture using standard methods. The most common organisms are Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila. Atypical bacterial pneumonia generally is characterized by a symptom complex that includes headache, low-grade fever, cough, and malaise. Constitutional symptoms often predominate over respiratory findings. Although in most cases presentation can be in the milder spectrum of community-acquired pneumonia, some cases, especially if caused by L pneumophila, may present as severe pneumonia, necessitating intensive care unit admission. Other possible pathogens include other Chlamydophila species, Legionella species, Coxiella burnetii (Q fever), and respiratory viruses.

Anamnesis y examen

Principales factores de diagnóstico

age <50 years
persistent cough
dry cough
long duration of symptoms

Todos los datos

Otros factores de diagnóstico

recent community exposure
throat involvement
fever
headache
diarrhea
bullous myringitis
lung rales/crepitations
rash

Todos los datos

Factores de riesgo

close community settings
immunosuppression
cigarette smoking
chronic lung disease
travel
male sex
immunomodulating drugs

Todos los datos

Pruebas diagnósticas

Primeras pruebas diagnósticas para solicitar

oxygen saturation in air
WBC count
hemoglobin
Liver function tests (LFTs)
BUN level
real-time reverse transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2
chest x-ray

Todos los datos

Pruebas diagnósticas que deben considerarse

urinary Legionella antigen
sputum culture
molecular diagnosis of Mycoplasma pneumoniae or Chlamydophila pneumoniae
nasopharyngeal PCR

Todos los datos

Algoritmo de tratamiento

Agudo

presumed atypical bacterial pneumonia: nonpregnant adult

presumed atypical bacterial pneumonia: pregnant or child

Colaboradores

Autores

Lorenzo Di Francesco, MD, SFHM, FACP

Professor of Medicine

Department of Medicine

Division of General Internal Medicine

Emory University School of Medicine

Divulgaciones

LDF is a Gen Medicine/Point of Care Editorial Board Member for ClinicalKey.

Revisores por pares

Mark Woodhead, BSc, DM, FRCP

Honorary Senior Lecturer (University of Manchester)

Consultant in General & Respiratory Medicine

Department of Respiratory Medicine

Manchester Royal Infirmary

Manchester

Divulgaciones

MW is an author of a reference cited in this topic.

Ethan Rubinstein, MD

H.E. Sellers Research Chair in Infectious Diseases

Head

Section of Adult Infectious Diseases

Department of Internal Medicine

Department of Medical Microbiology

University of Manitoba

Winnipeg

Canada

Divulgaciones

At the time of the peer review, Professor Rubinstein declared no competing interests. We were made aware that Professor Rubinstein is now deceased.

George L. Anesi, MD, MSCE, MBE

Assistant Professor

Medicine, Division of Pulmonary, Allergy, and Critical Care

Perelman School of Medicine

University of Pennsylvania

Divulgaciones

GLA receives research funding from the National Institutes of Health (K23HL161353), the CDC Foundation, the Society of Critical Care Medicine (SCCM), and the University of Pennsylvania Perelman School of Medicine Thomas B. McCabe and Jeannette E. Laws McCabe Fund. GLA reports payments for authoring chapters for UpToDate and for expert witness consulting, including involving COVID-19, and reports that his spouse is employed by the U.S. Food and Drug Administration (FDA).

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Referencias

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Artículos principales

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 Oct 1;200(7):e45-67.Texto completo Resumen

Lim WS, Baudouin SV, George RC, et al; Pneumonia Guidelines Committee of the BTS Standards of Care Committee. BTS guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009 Oct;64 Suppl 3:iii1-55.Texto completo Resumen

Artículos de referencia

Una lista completa de las fuentes a las que se hace referencia en este tema está disponible para los usuarios con acceso a todo BMJ Best Practice.

Diferenciales
- Coronavirus disease 2019 (COVID-19)
- Typical bacterial pneumonia
- Viral pneumonia
Más Diferenciales
Guías de práctica clínica
- Diagnosis and treatment of adults with community-acquired pneumonia
- Guidelines for the management of community acquired pneumonia in adults
Más Guías de práctica clínica
Folletos para el paciente
Pneumonia
Más Folletos para el paciente
Calculadoras
Community-acquired pneumonia severity index (PSI) for adults
CURB-65 pneumonia severity score
Más Calculadoras
Videos
Tracheal intubation: animated demonstration
Bag-valve-mask ventilation: animated demonstration
Más vídeos
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Atypical pneumonia

Resumen

Definición

Anamnesis y examen

Principales factores de diagnóstico

Otros factores de diagnóstico

Factores de riesgo

Pruebas diagnósticas

Primeras pruebas diagnósticas para solicitar

Pruebas diagnósticas que deben considerarse

Algoritmo de tratamiento

presumed atypical bacterial pneumonia: nonpregnant adult

presumed atypical bacterial pneumonia: pregnant or child

Colaboradores

Autores

Lorenzo Di Francesco, MD, SFHM, FACP

Divulgaciones

Revisores por pares

Mark Woodhead, BSc, DM, FRCP

Divulgaciones

Ethan Rubinstein, MD

Divulgaciones

George L. Anesi, MD, MSCE, MBE

Divulgaciones

Agradecimiento de los revisores por pares

Divulgaciones

Referencias

Artículos principales

Artículos de referencia

Una lista completa de las fuentes a las que se hace referencia en este tema está disponible para los usuarios con acceso a todo BMJ Best Practice.

Diferenciales

Guías de práctica clínica

Folletos para el paciente

Calculadoras

Videos

Inicie sesión o suscríbase para acceder a todo el BMJ Best Practice

Inicie sesión o suscríbase para acceder a todo el BMJ Best Practice

Inicie sesión para acceder a todo el BMJ Best Practice