OVERVIEW

What is atypical pneumonia?

The term "SARS" became widely known during the 2003 pandemic, but in medical terms, "atypical pneumonia" does not refer to a single disease. It is a concept defined in contrast to "typical pneumonia."

Broadly speaking, atypical pneumonia refers to all pneumonias not caused by common pathogens (such as streptococcal pneumonia).

Narrowly defined, atypical pneumonia refers to pneumonias caused by atypical bacteria, such as Legionella, Mycoplasma pneumoniae, or Chlamydia.

What is typical pneumonia?

Pneumonia can be classified in various ways based on the pathogen (bacteria, viruses, fungi, parasites), the environment of infection (community-acquired, hospital-acquired, ventilator-associated, etc.), or imaging findings (lobar, interstitial, obstructive, etc.).

Generally, pneumonia caused by typical pathogens is called "typical pneumonia," most commonly Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis.

Typical pneumonia usually presents with symptoms such as cough, sputum production, fever, rapid breathing, and chest pain. Chest X-rays or CT scans may show lung infiltrates or exudates, and it typically responds well to antibiotic treatment.

Is atypical pneumonia (SARS) the same as SARS?

Not exactly.

SARS stands for Severe Acute Respiratory Syndrome. During its outbreak in 2003, it was initially called "atypical pneumonia" due to limited understanding of the disease.

Later research revealed that "SARS" is an acute infectious respiratory disease caused by the SARS-CoV virus, characterized by fever, malaise, headache, muscle pain, dry cough, and in severe cases, difficulty breathing or respiratory failure. It was officially named SARS.

As mentioned earlier, atypical pneumonia, whether broadly or narrowly defined, is not entirely the same as SARS.

Is atypical pneumonia common?

Broadly defined atypical pneumonia is quite common, especially among children, pregnant women, elderly individuals with underlying conditions, and immunocompromised populations.

Even narrowly defined atypical pneumonia is not rare, accounting for about one-third of all pneumonia cases.

SYMPTOMS

What are the symptoms of atypical pneumonia?

Regardless of the cause, pneumonia is essentially inflammation and damage to the lung parenchyma resulting from pathogens breaching the body's normal defense system. Therefore, the symptoms are generally similar:

• From a local respiratory perspective, typical symptoms often include coughing, sputum production, shortness of breath, and chest pain;
• Systemically, symptoms may also include fever, chills, fatigue, muscle aches, and loss of appetite;
• Severe cases may present with respiratory distress, decreased consciousness, or shock.

How do the symptoms of atypical pneumonia differ from typical bacterial pneumonia?

Typical bacterial pneumonia primarily manifests with localized respiratory symptoms, such as coughing and sputum production, and may be accompanied by systemic symptoms like fever.

In contrast, atypical pneumonia often presents with systemic symptoms that are more severe than localized ones, such as pronounced fatigue, muscle pain, and mental sluggishness, and is frequently preceded by a prodromal phase without clear localized symptoms.

Additionally, atypical pneumonia has a higher tendency to progress to severe illness compared to typical bacterial pneumonia, increasing the risk of respiratory failure or even multi-organ dysfunction, leading to corresponding organ-related symptoms.

What serious complications can atypical pneumonia cause?

Atypical pneumonia typically causes more severe systemic symptoms and has a greater propensity for serious complications, including respiratory distress, respiratory failure, systemic inflammatory response, sepsis, septic shock, multi-organ failure, and even death.

Moreover, certain viruses causing atypical pneumonia exhibit varying degrees of contagiousness, potentially triggering regional or even global outbreaks and resulting in significant public health crises.

CAUSES

What are the pathogens that cause atypical pneumonia?

Broadly speaking, the pathogens causing atypical pneumonia include:

• Atypical bacteria: Legionella, Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, etc.;
• Respiratory viruses: Influenza A and B viruses, rhinovirus, adenovirus, coronaviruses (SARS-CoV, MERS-CoV, novel coronavirus, etc.), human bocavirus, etc.

How is atypical pneumonia transmitted?

The transmission routes of atypical pneumonia vary depending on the pathogen.

As a respiratory disease, it is mainly spread through droplets and close contact. Some highly contagious pathogens (such as Legionella, Coxiella, etc.) can also be transmitted via aerosols.

This means that unprotected close conversations, physical contact, or even sharing a relatively confined space with a confirmed atypical pneumonia patient may lead to infection.

However, it is important to emphasize that healthy individuals have a sufficiently strong self-defense system. Infection only occurs when the pathogen exposure is high enough and the immune defense system is compromised.

Who is more susceptible to atypical pneumonia?

As mentioned earlier, healthy adults can rely on their normal immune defense system to resist various pathogens.

In contrast, children, pregnant women, the elderly, smokers, obese individuals, and those with chronic comorbidities (such as bronchiectasis, asthma, chronic heart failure, diabetes, malnutrition, cancer, long-term corticosteroid use, etc.) are more prone to developing atypical pneumonia.

For highly contagious pathogens like SARS-CoV and MERS-CoV, the general population is universally susceptible, but the aforementioned high-risk groups are more likely to progress to severe illness.

DIAGNOSIS

What type of pneumonia does atypical pneumonia refer to?

It meets the diagnostic criteria for pneumonia: typical symptoms such as fever, cough, and shortness of breath; signs like tachypnea, lung rales, and decreased oxygenation; and imaging findings such as pulmonary infiltrates.

However, if the disease progresses rapidly, symptoms and signs do not match the severity of laboratory tests, conventional pathogen cultures yield no positive results, empirical antibiotic treatment is ineffective, or there is clear evidence of contagiousness or clustered cases, a diagnosis of atypical pneumonia may be considered.

What routine tests are needed when symptoms of atypical pneumonia appear?

When pneumonia symptoms occur, doctors first conduct a thorough physical examination, particularly auscultation and percussion of the lungs, to assess changes in breath sounds or dullness.

Next, routine laboratory tests are performed, including complete blood count, C-reactive protein, arterial blood gas analysis, and electrolyte tests, as well as imaging studies such as chest X-rays or lung CT scans.

Lastly, molecular diagnostics and microbiological tests are carried out, such as nasopharyngeal swabs, sputum or bronchoalveolar lavage cultures, blood cultures, Gram staining, viral antigen/antibody tests, and even immunofluorescence antigen detection.

It should be emphasized that, in general, microbiological diagnosis is not mandatory for typical or mild pneumonia cases, as the results do not alter treatment.

Patients with atypical pneumonia may exhibit specific findings in tests depending on the pathogen. For example, pneumonia caused by viruses or Mycoplasma often shows decreased rather than elevated white blood cell counts, interstitial or reticular patchy infiltrates on lung CT, and earlier and more severe hypoxemia on blood gas analysis.

What methods can confirm the pathogen causing atypical pneumonia?

Identifying the pathogen primarily relies on microbiological and molecular diagnostic techniques, such as nasopharyngeal swabs, sputum or bronchoalveolar lavage cultures, blood cultures, RT-PCR, and immunofluorescence antigen detection.

However, not all medical institutions are equipped to perform these tests. For certain critical pathogens (those causing severe epidemics and/or life-threatening diseases), such as influenza A/B, SARS-CoV, and MERS-CoV, national authorities have established specific diagnostic protocols and standards.

After identifying the pathogen in a suspected atypical pneumonia case, should it still be called "atypical pneumonia"?

Once the pathogen is confirmed, the pneumonia should preferably be referred to by the specific pathogen. However, it can still be categorized under the broader concept of "atypical pneumonia."

How can atypical pneumonia and influenza be distinguished?

The differences between atypical pneumonia and influenza mainly lie in their symptoms. Both can cause fever, significant systemic symptoms (e.g., headache, fatigue, muscle aches, malaise), and cough (often dry).

However, influenza is highly seasonal and epidemic, often presenting with more upper respiratory symptoms such as nasal congestion, runny nose, sneezing, sore throat, or throat irritation. It rarely leads to dyspnea or pneumonia complications.

Most influenza cases are self-limiting and do not require antibiotics, improving with symptomatic treatment alone. In contrast, atypical pneumonia primarily involves lower respiratory symptoms, and certain pathogens may also cause gastrointestinal symptoms like vomiting or diarrhea. Most cases require hospitalization and are more likely to progress to severe conditions such as dyspnea.

TREATMENT

Which department should I visit for atypical pneumonia?

Respiratory medicine, infectious diseases department, or communicable diseases department. Some severe cases may require ICU monitoring and treatment.

Can atypical pneumonia resolve on its own?

It depends on the pathogen and the severity of the illness.

Some young, otherwise healthy patients with mild atypical pneumonia and no severe complications may recover on their own with proper nutrition and rest.

However, it is still recommended to seek medical attention promptly if symptoms appear, especially for high-risk groups mentioned earlier, to avoid delaying treatment.

Is atypical pneumonia easy to treat? Can it be completely cured?

The treatment outcome and possibility of a full recovery depend on the pathogen, presence of complications, and the patient's overall condition.

For young, healthy patients, early and effective treatment can lead to full recovery. Treatment mainly involves supportive care, such as fever reduction, fluid replenishment, nutritional support, and bed rest. If there are specific medications targeting the pathogen, they may also be used.

However, high-risk groups—such as the elderly, pregnant women, those with underlying heart or lung diseases, cancer patients, or individuals on long-term corticosteroids or immunosuppressants—are more prone to severe illness and complications, requiring more complex treatment.

In addition to basic treatment, severe cases may need ICU care, intubation, mechanical ventilation, or blood purification. Some patients may also experience long-term complications.

That said, most severe patients can still recover after overcoming the acute phase of inflammation.

Is hospitalization always necessary for atypical pneumonia?

Not necessarily. Doctors will assess each case individually. Young, otherwise healthy patients with mild symptoms and no complications may be treated as outpatients, while high-risk groups often require hospitalization.

What are the common medications for atypical pneumonia?

Treatment varies based on the specific pathogen, regional prevalence, drug resistance patterns, the patient’s exposure history, allergies, and potential drug interactions.

For example, macrolides (e.g., azithromycin) or fluoroquinolones (e.g., moxifloxacin) may be used for mycoplasma pneumonia, while antiviral drugs like oseltamivir or zanamivir may be prescribed for influenza-related pneumonia.

However, some cases have no specific medication, so supportive care—such as fever reduction, hydration, nutrition, and rest—remains the best "treatment."

Is surgery ever needed for atypical pneumonia?

Surgery is rarely required. In acute cases, invasive procedures like intubation or pleural drainage may be necessary. A very small number of patients might later develop complications (e.g., empyema) requiring surgical drainage or lobectomy.

How long does it take to recover from atypical pneumonia if no complications arise?

The recovery time varies by pathogen, but most uncomplicated cases peak within about a week. Symptoms typically resolve within two weeks, though imaging findings may take longer—often a month or more—to fully clear.

Can atypical pneumonia cause long-term complications?

Mild cases usually leave no lasting effects. However, severe cases, especially in patients with preexisting heart/lung conditions or immune deficiencies, may result in complications, primarily affecting cardiopulmonary function.

Is the risk of death high with atypical pneumonia?

Overall, no.

Most patients recover fully, depending on the pathogen, their health status, and complications. However, high-risk groups—such as pregnant women, the elderly, or those with chronic conditions (e.g., asthma, heart failure, diabetes, cancer, or malnutrition)—face a higher risk of severe illness and mortality.

DIET & LIFESTYLE

What dietary precautions should be taken during the treatment of atypical pneumonia?

For mild cases of atypical pneumonia, a normal diet is sufficient. Maintain regular meals, increase the intake of fresh vegetables and fruits, and consume high-quality proteins such as fish and shrimp. Avoid greasy and spicy foods. Increase water intake appropriately, especially if fever is present.

Severe patients, particularly those with serious complications, may be unable to eat orally and may require enteral nutrition through a nasoenteric tube or intravenous fluids and parenteral nutrition. Oral feeding should be resumed as soon as the condition improves.

What lifestyle precautions should be taken during the treatment of atypical pneumonia?

During the acute phase of atypical pneumonia, rest is recommended. Ensure adequate sleep, avoid fatigue and exercise, maintain a proper diet, and refrain from smoking and alcohol. Wash hands frequently, wear masks correctly, and strictly self-isolate if the pathogen is contagious to prevent disease transmission.

How can caregivers assist atypical pneumonia patients in expectoration?

For patients who have difficulty expectorating, caregivers can pat the lungs to vibrate the airways and help expel phlegm. The steps are as follows:

• Position: Have the patient lie on their side or sit up. The caregiver should cup their hands slightly and use wrist movements to create vibrations.
• Location: Pat the patient’s back or chest from bottom to top, moving from the sides inward. Avoid the breasts, heart, bony areas, and clothing zippers or buttons.
• Speed and duration: Pat at a rate of 2–3 times per second, covering the upper, middle, and lower back for 1–3 minutes on each side. Repeat every few hours if phlegm is excessive. Avoid patting within an hour after meals.

Proper patting should produce a hollow sound. Observe the patient’s reaction and stop immediately if discomfort occurs, seeking professional help if needed.

Can work and study be resumed normally after recovering from atypical pneumonia?

Most patients can return to normal work and study after recovery, gradually increasing intensity to pre-illness levels.

However, a small number of severe cases may experience lasting damage to heart or lung function, making it impossible to fully resume previous workloads. It is important to act within one’s limits and avoid overexertion.

Can exercise be resumed normally after recovering from atypical pneumonia?

Mild cases can resume normal exercise after recovery. Severe cases may require evaluation of lung, heart, and other organ functions for residual damage. If functional impairments exist, rehabilitation exercises should be conducted under medical supervision, gradually increasing intensity based on tolerance. Monitor physical reactions closely and exercise within one’s limits.

PREVENTION

How to prevent atypical pneumonia?

• Lifestyle measures:

  • Do not smoke and avoid exposure to secondhand smoke.
  • Maintain a healthy diet and exercise regularly, 3-5 times per week for 30 minutes each session, combining aerobic and strength training at moderate intensity without overexertion.
  • Develop good hygiene habits, wash hands frequently, and ensure proper ventilation at home.
  • Stay warm during disease-prone seasons, avoid crowded places, wear masks when in contact with patients, and disinfect clothing promptly after returning home.

• Medication prevention:

  • For children, pregnant women, and elderly individuals with underlying conditions, annual influenza and pneumococcal vaccines are recommended to effectively prevent pneumonia caused by certain pathogens.
  • However, taking "preventive medications" without symptoms is not advised, especially traditional Chinese medicines or immunity-boosting supplements.

Which vaccines can effectively prevent pneumonia in children?

Children aged 6 months and above can receive influenza and pneumococcal vaccines. For specifics, consult local disease control centers or community hospitals.

Do adults need vaccines to prevent pneumonia?

Yes, particularly the influenza vaccine, which is recommended for healthy adults under 65. It is strongly advised for those over 65, high-risk groups (e.g., pregnant women, immunocompromised individuals, elderly with cardiopulmonary diseases, close contacts, and frontline healthcare workers). Note that vaccines require annual administration, ideally before the peak season.

Elderly individuals are also advised to receive pneumococcal vaccines.