Atypical pneumonia

Generality

Atypical pneumonia is the medical expression attributable to all those forms of infectious pneumonia, due to pathogens different from those classically involved in the processes of inflammation of the lungs (typical or classical pneumonia).

Except for rare exceptions, atypical pneumonia is a milder symptomatic condition of classical pneumonia, which makes it a disease with a lower risk of complications and from which it is easier to heal.

Among the pathogens capable of causing atypical pneumonia, there are mainly bacteria, such as Mycoplasma pneumoniae, Legionella pneumophila and Chlamydophila pneumoniae .

For the diagnosis of atypical pneumonia, they are essential: medical history, physical examination, oximetry and chest radiography; sometimes, a blood test is also needed, in order to pinpoint the pathogen responsible for the infection.

Treatment of atypical pneumonia involves causal therapy, combined with symptomatic therapy.

Medical meaning of the term pneumonia

In medicine, the term " pneumonia " means inflammation, almost always of infectious origin, of the lungs and, possibly, also of the respiratory tracts connected to the lungs (ie bronchi, bronchioles and alveoli ).

What is Atypical Pneumonia?

Atypical pneumonia is the particular infectious pneumonia, which depends on pathogens different from those usually involved in inflammatory processes affecting the lungs.

In essence, therefore, with the expression "atypical pneumonia" the doctors mean all those forms of pneumonia, in which the triggering pathogen is not one of the typical ones, but is an unusual microorganism for the type of inflammation in question.

Compared to the more classic forms of pneumonia ( typical or classical pneumonia ), atypical pneumonia is less severe and debilitating (with some exceptions); this explains why, in Anglo-Saxon-speaking countries, it is also called " walking pneumonia ", which in Italian would mean "pneumonia that allows the patient to walk" (the possibility of walking indicates less debilitation, compared to the classic forms of pneumonia ).

Readers are reminded that ...

The pathogens typically responsible for pneumonia (ie the pathogens of classical polmoinite) are, in order of importance: Streptococcus pneumoniae (the so-called Pneumococcus ), Haemophilus influenzae and Moraxella catarrhalis .

Primary atypical pneumonia

The most exact name of atypical pneumonia is primary atypical pneumonia, where the word "primary" expresses:

• The independence of the pneumonia in question from other morbid conditions

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• The dependence of inflammation on a problem inherent in the lung (the inflammatory state depends on a pathogen that has proliferated at the level of the lungs).

Causes

The main pathogens responsible for atypical pneumonia are bacteria:

• Mycoplasma pneumoniae (we read "mycoplasma pneumoniae"). At the forefront of the causes of atypical pneumonia, it most frequently affects young people and adults under 40 years.
• Chlamydophila pneumoniae (we read "chlamydophila pneumoniae"). Because of a very mild form of typical pneumonia, it affects more often the very young and young adults.
• Legionella pneumophila (we read "legionella pneumofila"). It causes a very severe form of atypical pneumonia, sometimes with a fatal outcome, which doctors call legionellosis or legionnaire's disease ; Legionella pneumophila infects older people, smokers and individuals with weak immune systems more frequently.

Other causes of atypical pneumonia

Although at a much lower frequency than the three bacteria mentioned above, other pathogens can cause atypical pneumonia; among the pathogens in question, there are other bacteria, viruses and fungi.

OTHER BACTERIA RESPONSIBLE FOR POLYMONITE ATIPICA

The bacteria included in the list of rare causes of atypical pneumonia are:

• Chlamydophila psittaci . It is the pathogen of so-called psittacosis .
• Coxiella burnetii . It is the pathogen of the so-called Q fever .
• Francisella tularensis . It is the pathogen of the so-called tularemia .

VIRUSES RESPONSIBLE FOR POLYMONITE ATIPICA

In the list of viruses that, in rare circumstances, can produce atypical pneumonia, include: respiratory syncytial virus (RSV), influenza A virus, influenza B virus, parainfluenza virus, adenovirus and the SARS virus (Severe Acute Respiratory Syndrome).

MUSHROOMS RESPONSIBLE FOR ATYPIC PULMONITE

The fungi that can sometimes cause atypical pneumonia are: Aspergillus fumigatus, Aspergillus niger, Candida albicans, Candida glabrata, Candida Krusei, Candida lusitaniae, Histoplasma capsulatum, Pneumocystis jirovecii, Blastomyces dermatitidis, Coccidioides immitis, Coccidioides posadasii, Sporothrix schenckii and Cryptococcus neoformans .

Contagiousness and dissemination methods

Generally, atypical pneumonia is the result of a contagious infection, which is an infection that can spread from a sick individual to a healthy one.

The diffusion in an unhealthy person of atypical pneumonia usually takes place through aerosol droplets emitted by a patient, during sneezing, coughing or when talking, or through contact with a surface previously touched by an infected subject (in this second circumstance, to get sick, it is essential that the part of the body exposed to the contaminated surface subsequently enters into contact with the mucous membranes of the mouth, eyes or nose).

Atypical pneumonia due to Legionella pneumophila almost always spreads only through aerosol droplets, emitted by the sick during sneezing, coughing, etc.

Risk factors

Atypical pneumonia can affect anyone; however, statistics show that this pulmonary inflammation is more frequent among:

• Smokers
• People over the age of 65;
• Individuals under the age of 2;
• People with chronic respiratory diseases (eg: COPD);
• Immunosuppressed, ie those with reduced immune defenses (eg, AIDS patients).

According to some investigations, moreover, it would be more at risk of atypical pneumonia anyone who, for work reasons, frequently comes into close contact with people suffering from the condition in question.

Symptoms and Complications

Except when supported by Legionella pneumophila, atypical pneumonia is a condition with mild symptoms and an impact on the health of the patient that is less severe than in the case of classical pneumonia (eg Streptococcus pneumoniae pneumonia ).

The possible symptoms of atypical pneumonia are numerous and can be divided according to the frequency of occurrence into: common symptoms, intermediate frequency symptoms and uncommon symptoms.

Common symptoms of atypical pneumonia

The common symptoms of atypical pneumonia are - as the term "common" says - the most frequent.

These include:

• Chills;
• Cough. Atypical pneumonia from Legionella pneumophila can cause cough with blood emission (hemoptysis);
• Temperature. It is generally mild, but, in the presence of a Legionella pneumophila infection, it can also be high;
• Shortness of breath during physical efforts (or dyspnea on exertion).

Intermediate frequency symptoms of atypical pneumonia

Symptoms of atypical pneumonia with an intermediate frequency include:

• Chest pain. Generally, this disorder worsens with coughs or deep breaths;
• Confusional state. It is more common in elderly patients and in patients with atypical pneumonia of Legionella pneumophila ;
• Headache;
• Loss of appetite, lack of strength and sense of recurring fatigue;
• Muscle pain and joint stiffness;
• Profuse sweating.

Uncommon symptoms of atypical pneumonia

Uncommon symptoms of atypical pneumonia are the rarest disorders to observe in a patient.

The list of these infrequent events includes:

• Diarrhea. It is observable in atypical pneumonia with Legionella pneumophila ;
• Ear pain. It is especially observed in atypical pneumonia with Mycoplasma pneumoniae ;
• Eye pain or soreness. More often it characterizes atypical pneumonia from Mycoplasma pneumoniae ;
• Swollen lymph nodes on the neck. Most frequently characterizes atypical pneumonia from Mycoplasma pneumoniae ;
• Skin eruptions. It is most frequently detectable in atypical pneumonia with Mycoplasma pneumoniae ;
• Sore throat. It is most often found in atypical pneumonia with Mycoplasma pneumoniae .

Incubation times: when do the first symptoms appear?

Atypical pneumonia has longer incubation times than classical pneumonia and other respiratory infections, such as the common flu or the common cold. In fact, if in the classical pneumonia, in the flu and in the cold the first symptoms appear within a few days, in the atypical pneumonia the first characteristic disorders emerge after 1-4 weeks from the infection.

Evolution of symptomatology

In general, the symptomatology of atypical pneumonia worsens (while remaining always less severe than that present during classical pneumonia) within 2-6 days.

Complications

Although it happens very rarely, the following complications can arise from atypical pneumonia:

• Brain and nervous system infections, such as encephalitis, meningitis or myelitis;
• Hemolytic anemia ;
• Severe damage to lung tissue, resulting in conditions such as COPD.

Diagnosis

In general, doctors arrive at the diagnosis of atypical pneumonia after: a thorough medical history, a thorough physical examination, measurement of oxygen levels in the blood ( oximetry ) and chest radiological examination ( RX-thorax ).

In some situations, the diagnostic procedure for the detection of atypical pneumonia also involves a series of blood tests aimed at establishing with precision the pathogenic agent present (usually, they are indicated when atypical pneumonia has a bacterial origin).

history

A medical history useful for identifying atypical pneumonia consists of a questionnaire (clearly aimed at the patient), whose questions focus on the characteristics of the symptomatology (eg: what are the symptoms in place? When did the first disorders appear? Etc.).

Physical examination

An objective physical examination for the detection of atypical pneumonia includes: measurement of body temperature, measurement of respiratory and pulse frequency and auscultation of the chest.

Oximetry

Oximetry is a quick, simple and painless exam, through which the diagnostic doctor establishes the saturation of oxygen in the blood.

Chest x-ray

Chest X-ray represents the diagnostic confirmation of what is only assumed with previous investigations. The chest X-ray, in fact, allows to recognize an inflammation of the lungs and distinguish it from all other lung diseases of different nature.

How to distinguish atypical pneumonia from classical pneumonia

In the diagnostic field, the parameter that allows doctors to distinguish atypical pneumonia from classical pneumonia is the degree of severity of the symptoms.

An exception, compared to what has just been stated, is atypical pneumonia due to Legionella pneumophila : to distinguish the latter from classical pneumonia, laboratory tests are required to identify the responsible pathogen.

Therapy

In general, the treatment of atypical pneumonia involves a causal therapy - that is a therapy aimed at counteracting the pathogen responsible for the condition - and a symptomatic therapy - that is a therapy aimed at alleviating the ongoing symptoms.

Since atypical pneumonia almost always has a bacterial origin, in this article the attentions are directed exclusively to the treatment provided when the cause of lung inflammation is a bacterium.

Causal therapy

The causal therapy of atypical pneumonia of bacterial origin is based, essentially, on the administration of antibiotics, ie drugs with antibacterial properties.

Sometimes, to find out what the best antibiotic is, doctors need to identify with precision, through specific laboratory tests, the bacterial agent responsible for the condition in progress.

Duration of antibiotic therapy

As a rule, antibiotic treatment in the presence of atypical pneumonia lasts 2 weeks.

Symptomatic therapy

Premise: the symptomatic therapy described in the next lines is valid whatever the cause.

As a rule, symptomatic therapy useful in the presence of atypical pneumonia includes:

• Rest ;
• Taking NSAIDs, aspirin or paracetamol, to mitigate symptoms such as fever, muscle pain, etc. It is recalled that aspirin is contraindicated in children;
• Consumption of a lot of water, to dissolve phlegm and mucus, and to avoid dehydration.

What to do in severe cases?

When supported by Legionella pneumophila or when it affects an immunodepressed subject, atypical pneumonia requires hospitalization and a series of treatments, which can only take place in a specialized facility.

Prognosis

Atypical pneumonia tends to have a benign prognosis, except when it is due to Legionella pneumophila ; when in fact the latter is the responsible pathogen, the treatment of the condition is more complex and it is easier for complications to arise, the outcome of which can sometimes be fatal.

Prevention

Washing hands regularly, avoiding smoking, staying away from people with atypical pneumonia (especially in the presence of a state of immunodepression) and eating healthy are among the most important behaviors when the topic of discussion is the prevention of atypical pneumonia.