Overview.
Chlamydia pneumonia is pneumonia caused by Chlamydia, which is categorized as Chlamydia trachomatis (CT), Chlamydia pneumoniae (CP) Chlamydia psittaci and Chlamydia domestica. Pneumonia caused by Chlamydia trachomatis (CT), Chlamydia pneumoniae (CP), Chlamydia pneumoniae and Chlamydia householder. Chlamydia pneumonia is most common in school-age children, and most cases are mild and often insidious. There is no gender difference in the prevalence of infection and it can occur in all seasons.
Causes
Chlamydia pneumoniae infection in humans is universal. The route of Chlamydia pneumoniae transmission is through person-to-person transmission of respiratory secretions. Therefore, small epidemics can exist in semi-enclosed environments such as homes, schools, the military, and other populated work areas. Chlamydia pneumoniae infection may also be associated with the development of asthma, coronary heart disease and atherosclerosis, and acute exacerbations and worsening of chronic obstructive pulmonary disease. Currently, Chlamydia pneumoniae is the major pathogen causing community-acquired pneumonia after S. pneumoniae and Haemophilus influenzae, and together with Legionella pneumophila and Mycoplasma pneumoniae, it is one of the three atypical pathogens of community-acquired pneumonia, which account for 10% to 20% of community-acquired pneumonia.
Symptoms
The onset of the disease is insidious, with early presentation of symptoms of upper respiratory tract infection. Clinically, it is quite similar to Mycoplasma pneumonia. Symptoms are usually mild, with fever, chills, myalgia, dry cough, non-pleuritic chest pain, headache, malaise and malaise. Hemoptysis is rare. Those who develop pharyngolaryngitis present with sore throat and hoarseness, and some patients may present with a two-stage course: pharyngolaryngolaryngitis at the beginning, which improves with symptomatic management, and then pneumonia or bronchiolitis with worsening of the cough 1 to 3 weeks later. Chlamydia pneumoniae infection can also be accompanied by extrapulmonary manifestations, such as otitis media, arthritis, thyroiditis, encephalitis, Guillain-Barré syndrome. Occasional wet rales are heard in the lungs on physical examination.
Examination
1. Laboratory examination
(1) White blood cell count and classification results are usually normal, but most of the blood sedimentation is fast.
(2) Culturing of Chlamydia pneumoniae Culturing of specimens such as nasopharyngeal or posterior pharyngeal swabs, tracheal and bronchial secretions, and alveolar lavage fluid.
(3) Microimmunofluorescence test (MIF) is currently the international standard and the most commonly used serological diagnostic method for Chlamydia pneumoniae. Except for STD clinic patients and specific groups of prostitutes, MIF serological diagnosis of Chlamydia pneumoniae pneumoniae can be made using a single antigen of Chlamydia pneumoniae, i.e., it is not necessary to test antibodies against Chlamydia trachomatis and Chlamydia psittaci at the same time. Serologic diagnostic criteria are: MIF test IgG ≥1:512 and/or IgM ≥1:32, after exclusion of false positives due to rheumatoid factor (RF) can be diagnosed as a recent infection, double serum antibody titer 4-fold or more elevated is also diagnosed as a recent infection. 1:16 ≤ IgG <1:512 is considered as a previous infection.
2. Other auxiliary examinations
X-ray chest radiographs begin with unilateral alveolar infiltration and progress to bilateral interstitial and alveolar infiltration.
Diagnosis
The clinical symptoms and X-ray manifestations of Chlamydia pneumoniae lung infection are nonspecific and cannot be differentiated from other atypical pneumonias, especially Mycoplasma pneumoniae, so the definitive diagnosis depends on laboratory diagnosis. The most reliable method is to culture Chlamydia pneumoniae by taking swabs from the nasopharynx or posterior pharyngeal wall, tracheal and bronchial secretions, alveolar lavage fluid and other specimens. However, due to the high requirements of Chlamydia pneumoniae culture, it is difficult for general laboratories to do so. The application of PCR test to the above specimens is very helpful for diagnosis, but quality control needs to be paid attention to prevent false positive results.
Microimmunofluorescence test (MIF) is currently the international standard and most commonly used diagnostic method for serologic diagnosis of Chlamydia pneumoniae.
Complications
Often secondary to bacterial infection, combined with endocarditis, myocarditis, etc.
Treatment
1. Antibiotic treatment
The first choice of treatment is erythromycin, or doxycycline. In recent years, there are also reports on the use of clarithromycin and azithromycin for the treatment of Chlamydia pneumoniae infection, in which azithromycin’s efficacy is better than clarithromycin, but the experience of clinical application is still scarce. Chlamydia pneumoniae is also sensitive to fluoroquinolones, such as oxfloxacin or tolfloxacin can be used in the treatment of adult patients, but not recommended for children.
2.Precautions
The course of antibiotics must be adequate to prevent recurrence. If the dose of erythromycin is too small or the course is too short, symptoms such as generalized malaise and cough often persist for months.
Prognosis
Without treatment, the disease usually resolves gradually even after a few weeks. However, the lung rales and the lesions seen on radiographs will not resolve for months. The prognosis is poorer in elderly patients or in patients with certain chronic diseases, such as COPD or secondary to other bacterial infections of the lungs.