Mycoplasma pneumonia
Mycoplasma pneumonia is a bacterial infection affecting the lungs, characterized as an atypical pneumonia. Caused by the Mycoplasma pneumoniae bacterium, it is notable for its lack of a cell wall and its ability to survive in various environments. Transmission occurs primarily through respiratory droplets, making individuals in crowded settings—such as schools, military facilities, and hospitals—particularly susceptible. Symptoms typically develop over one to three weeks and can include malaise, fever, coughing, and sore throat, alongside potential extrapulmonary manifestations like chest pain and muscle aches.
Diagnosis usually involves a thorough medical history, physical examination, and various tests, including chest X-rays and PCR testing for the bacteria. Treatment primarily involves antibiotics, such as macrolides and fluoroquinolones, with additional therapies for any extrapulmonary symptoms. Preventive measures focus on reducing the spread of respiratory droplets and may include antibiotic prophylaxis to limit infections in at-risk populations. Understanding Mycoplasma pneumonia is essential for effective management and prevention of outbreaks, particularly in communal living situations.
Mycoplasma pneumonia
- ANATOMY OR SYSTEM AFFECTED: Lungs, respiratory system
- ALSO KNOWN AS: Atypical pneumonia, walking pneumonia
Definition
Mycoplasma pneumonia is a bacterial infection of the lungs. The infection is considered an atypical pneumonia.
Causes
The etiologic agent is Mycoplasma pneumoniae, a bacterial species found to be widespread in the environment. This bacterium, which has no cell wall, can survive in the presence or absence of oxygen. It has a specialized tip (organelle) that provides motility and mediates bacterial interactions with its host cells. Moreover, adherence proteins allow M. pneumoniae to attach to the lining of the respiratory tract (from the nasal passage to the lungs), acting like a parasite on the surface of its host cells. The bacteria produce hydrogen peroxide and superoxide, substances that injure the respiratory lining.
Risk Factors
M. pneumoniae is transmitted through respiratory droplets between people. Persons who are in close contact are at highest risk for this infection, including those who live, work, or perform activities in crowded places such as schools, homeless shelters, prisons, dormitories, military facilities, and hospitals. Other associated risk factors for Mycoplasma respiratory infection include smoking and lower levels of preexisting immunoglobulin G levels. The disease appears to be most common in school-aged children. Preexisting lung conditions and a weakened immune system are additional risk factors.
Symptoms
The symptoms of Mycoplasma pneumonia gradually appear from one to three weeks after infection. Symptoms may be divided into those of the respiratory tract (pulmonary) versus those with extrapulmonary manifestations (cardiologic, neurologic, dermatologic, and others). The general symptoms include malaise, fever, chills, and excessive sweating, which may precede the onset of illness. The common pulmonary symptoms include nonproductive cough, runny nose, wheezing, and sore throat. Extrapulmonary symptoms may include chest pain, headache, eye pain, muscle aches, joint stiffness, skin rash, and a breakdown of red blood cells. Central nervous system involvement may manifest as encephalitis and meningitis.
Screening and Diagnosis
A physician will obtain a medical history, perform a physical examination, and evaluate the list of symptoms. A chest X-ray will be ordered along with laboratory studies (complete blood count and basic electrolytes). Other diagnostic tests include nasopharyngeal or oropharyngeal swabs for polymerase chain reaction (PCR) testing. Serology tests may also be obtained to evaluate the presence and levels of antibodies against Mycoplasma antigens. PCR testing for the detection of Mycoplasma genetic material has become one of the main methods of diagnosis. Mycoplasma antigens or cold agglutinins are less commonly used. Depending on the severity of the clinical presentation, a computed tomography (CT) scan of the chest and bronchoscopy (in which a thin fiberoptic scope is used to view the respiratory tract and the lungs) may be performed. Open lung biopsy is done only in serious illnesses when the diagnosis is uncertain or the person’s symptoms are not resolved.
Treatment and Therapy
Antibiotic options against M. pneumoniae include macrolides (such as azithromycin, clarithromycin, and erythromycin), fluoroquinolones (such as levofloxacin and moxifloxacin), and tetracyclines (such asdoxycycline). Adjunct therapies may be necessary if extrapulmonary symptoms are present. For example, steroids have shown benefits for treating children with neurologic disease.
Prevention and Outcomes
Antibiotic prophylaxis with azithromycin has been shown to prevent outbreaks of Mycoplasma pneumonia and to decrease the occurrence of respiratory infections. Another preventive measure is minimizing the transfer of respiratory droplets from infected persons to others.
Bibliography
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