Pneumocystis pneumonia( Pneumocystis) - Causes, symptoms and treatment. MF.
Pneumocystis is caused by non-pathogenic microorganisms, so among healthy people there are no symptoms of the disease in the presence of antibodies in the blood. Clinically expressed forms of the disease can form only in the body with immunodeficiency, which is up to 45-50% of all patients with immune deficiency. Among HIV-infected patients, this proportion is up to 70%, as a result of which pneumocystis is an AIDS indicator of an opportunistic disease.
Pneumocystis pneumonia is an anthroponous infectious disease caused by protozoan Pneumocystisjiroveci( formerly Pn. Carini), with airborne transmission that occurs against the background of immunological failure and manifests itself in a mildly infectious-toxic syndrome and respiratory infection - of the lungs and small bronchi with the possibilitydevelopment of respiratory failure.
Pneumocystiscarinii was first described in 1909 and isolated in 1912, at that time the pathogen was not considered to be pathogenic to humans. It was in 1942 that the pneumocyst was indicated as the cause of interstitial pneumonia during an outbreak in newborn infants and in children with immunity defects. Since 1980, previously referred to the simplest pneumocyst was already classified in a class that occupies an intermediate position between fungo-fungi and higher fungi, as evidenced by general biochemical properties and morphology.
Pneumocysts
Causes of pneumocystis pneumonia
The causative agent is the average between protozoa and fungi Pneumocystisjiroveci by the name of the Czech scientist Otto Jirowitz, who first described the causative agent of the pulmonary form of the disease( the previous name for the genus Pneumocystiscarinii).This pathogen is pathogenic for healthy people, therefore, the disease can occur in immunocompromised individuals. Pneumocysts are tropic exclusively to pulmonary tissue, that is, the main symptoms are symptoms of lung damage. When multiplying, the causative agent excretes various metabolic products that have weak pathogenic properties, so the infectious-toxic syndrome( fever and intoxication) is not expressed in pneumocystis pneumonia.
The cycle of pneumocyst development. Pneumocystisjiroveci( carinii) is an extracellular parasite and has its own development cycle that flows inside the alveoli - the structural element of the lung. The cycle includes 4 stages: trophozoite, precyst, cyst, sporozoite.
The cycle of pneumocyst development
When propagating pneumocysts, vegetative forms of the pathogen are formed - trophozoites( unicellular microorganisms having a core, a 2-layer membrane, up to 5 μm in diameter).Trophozoites are attached to the cells of the epithelium - alveocytes and begins to change: it becomes oval, and its membrane thickens( a precyst is formed).Further development continues in the cyst with a diameter of up to 8 μm, which has a thick wall consisting of 3 layers. The wall of the cyst contains glycoproteins, one of which p120 is necessary for binding to the alveocytes of the lung epithelium. Inside the cysts are intracystal small up to 3 μm of formation - sporozoites, the number of which can vary from 5 to 8 pieces. If the study found mature cysts with a large number of sporozoites, then this is evidence of an active infection.
There are 2 phases of development: sexual and asexual. The difference is that in the sexual phase, mature cysts are destroyed, sporozoites are isolated, which, merging in pairs, form trophozoites and then through the stages. In the asexual phase, there is a division of trophozoites and each becomes a cyst.
Cysts
Source of infection is a sick person or a carrier: it can be family members, employees of organized children's groups, medical institutions. Pneumocyst carriers can also be animals - rats, mice, cats, dogs, pigs, rabbits. Among healthy up to 10% carriers of pneumocysts.
The infection mechanism is aerogenic, and the path is airborne. Pneumocysts spread with particles of mucus, sputum when coughing, sneezing. An air-dust transmission path is also possible. An additional mechanism is the transplacental( from the mother to the fetus), and the evidence of intrauterine infection is the occurrence of pneumocystis pneumonia during the 1st month of the child's life.
Population susceptibility is universal, however, in the general group of patients, men prevail. The incidence is recorded sporadically( that is, individual cases of PCP are detected).A distinct seasonality is not typical, but there is an increase in the number of patients in the spring-summer period. The bulk of patients with pneumocystis are individuals with immunodeficiency.
Examples of human immunodeficiency:
1) physiological age-related failure( young children, elderly people);
2) infants younger than 1 year old, born with signs of prematurity, asphyxia, congenital malformations of the lungs, heart;
3) older children and adults who have any chronic or severe illness or who are forced to take cytotoxic drugs, glucocorticosteroids, radiation therapy( oncological diseases, blood diseases);
4) Patients with chronic diseases( rheumatoid arthritis, systemic lupus erythematosus, chronic nonspecific lung diseases, liver cirrhosis and other conditions);
5) HIV infection( up to 70% of patients with pneumocystis).
Accordingly, the risk groups for pneumocyst infection are:
• Children are children of children's homes.
• People of advanced age who are in nursing homes.
• Oncological patients receiving immunosuppressants.
• Patients with blood diseases( leukemia and others).
• Patients with tuberculosis, HIV infection, cytomegalovirus and other infections.
• Patients on treatment with glucocorticosteroids.
Immunity after the transferred infection is not persistent, repeated infections associated with infection with a new genotype of the pathogen are possible. In immunodeficient persons who have suffered pneumocystis pneumonia, relapses are possible in 10% of cases, in patients with HIV infection in the AIDS stage - in every 4 cases.
Pathogenic action on the body
1) Pneumocysts enter the human body through the respiratory tract and find themselves in the lumen of the small bronchi, the alveoli, where they multiply actively( as a result of longitudinal division an oocyst is formed, which subsequently is surrounded by a mucous capsule).During this period, the patient's lumen of small bronchi and alveoli is filled with mucus almost completely. All this leads to a difficulty in advancing air through the patient's airways - a pronounced respiratory failure.
2) During the propagation of pneumocysts, metabolic products are formed that enter the bloodstream and cause sensitization of the body and the formation of specific antibodies. In parallel, the products of metabolism exert an irritating effect on phagocytosis cells, which are attracted to the lesion site. All this leads to inflammatory infiltration of the walls of the alveoli of the lungs and to the diffusion of gases( oxygen-carbon dioxide), which is another cause of respiratory failure.
3) With a long-term process - a protracted nature of the disease - fibroblasts are formed, and
, in other words, pulmonary fibrosis. There may be complications( emphysema, closed pneumothorax).
Symptoms of pneumocystis pneumonia
The incubation period for PCP is from a week to 10 days, an average of 6-7 days. Pneumocystis can occur in the form of acute respiratory disease, laryngitis, exacerbations of chronic bronchitis, but more often in the form of pneumocystis interstitial pneumonia.
There are 3 stages of the disease:
1) edematous( 7-10 days);
2) atelectatic( up to 4 weeks);
3) emphysematous( 1-3 or more weeks).
Stage 1 - edematous.
Symptoms of intoxication and fever are not leading. The temperature can be both normal and subfebrile( less than 38º).Patients may be troubled by weakness, increased fatigue, decreased efficiency, decreased appetite, body weight may be normal or decreased. Respiratory syndrome is poorly expressed - there may be a rare cough with hard-to-separate viscous sputum. When listening to the lungs( auscultation), hard breathing, there is no rattling. Percussion( with tapping of the lungs) - shortening of percussion sound in the interblade area.
Stage 2 - atelectatic.
Increases respiratory syndrome - in patients, dyspnea appears and grows( up to 60-80 respiratory movements per minute in adults), with the involvement of ancillary muscles, cyanosis appears( a cyanotic shade of the skin), it is possible to develop pulmonary-cardiac insufficiency. Cough becomes obtrusive and frequent, phlegm is thick, transparent and difficult to retract. In addition, small and medium bubbling rales are heard. Percussion - shortening of sound in interblade areas, less often over large foci, increasing "tipmanit"( loud musical sound, like knocking on a drum, box sound) in the anterior-upper parts of the lungs.
In this stage, the development of a complication is possible - sickle-shaped pneumothorax, which does not threaten the patient's life, self-sufficient for 1-2 days.
Stage 3 - emphysematous.
In this stage, there is an improvement in the state of health - a cough is reduced, dyspnea is stopped. For a long time there is a box sound with percussion of the lungs, as well as dry wheezes at auscultation.
The most common process in pneumocystis pneumonia is limited to pulmonary tissue, but with severe immunodeficiency, hematogenous and lymphogenous spread is possible with the appearance of extrapulmonary manifestations: lesions of the liver, spleen, thyroid, adrenals, heart, and others. Extremely rare is an ENT pathology( sinusitis, otitis, sinusitis).
Peculiarities of pneumocystosis:
1) In most patients, the disease occurs abnormally: some patients resemble ARI patients, accompanied by obstructive bronchitis, poorly amenable to therapy;in some patients, the disease has abortive course( a sharp interruption of the symptoms of the disease).
2) Pneumocystis pneumonia has a tendency to recurrent course, contributing to the development of chronic fibrotic processes in the lungs.
Peculiarities of pneumocystis pneumonia in children:
1) The time of onset is most often at 5-6 months of life in risk groups( premature babies, rickets, CNS, VUI, HIV, oncology).
2) The gradual onset of the disease - poor appetite, poorly increases weight, and then does not add at all, low-grade fever, coughing similar to cough in whooping cough, accompanied by shortness of breath( up to 70 or more respiratory movements per minute), pale skin with cyanoticcyanotic) shade. With a weighting of symptoms, complications may develop - pulmonary edema with a lethal outcome.
3) At a roentgenography - focal shadows "cloud-like" lung. In UAC - an increase in eosinophils, ESR, leukocytes.
Features in HIV-infected patients( especially at the AIDS stage):
Pneumocystis pneumonia is the leading opportunistic disease in HIV infection.
1) Due to the frequent combination of pneumocystis pneumonia with other bacterial infections, the symptoms can include a pronounced infectious-toxic syndrome( fever, intoxication), coughing and shortness of breath can act in the background. In some patients, the disease is "under the mask" of ARI.
2) Prolonged to chronic and chronic course of the disease.
3) Obstructive diagnosis of infection due to the combination of bacterial lesions.
Pneumocystis pneumonia in HIV-infected people, microscopy
The histological picture of pneumocystosis can also be characterized by three stages:
. In the initial stage there are no inflammatory changes in the alveoli, it is possible to identify trophozoids and cysts.
The intermediate stage of the histological pattern coincides with the clinical manifestations and is characterized by changes in the alveolar epithelium, the abundance of macrophages inside the alveoli, and the detection of a large number of cysts.
The final stage is characterized by the development of alveolitis, alveolar epithelial changes, interstitial epithelial infiltration. The abundance of cysts is revealed both in the lumen of the alveoli, and inside the macrophages.
Complications of pneumocystis pneumonia
Complications of pneumocystis pneumonia can be a lung abscess, spontaneous pneumothorax, exudative pleurisy.
The outcomes of pneumocystosis can be: recovery, lethal outcome from 1 to 100% with severe immunodeficiency( for example, AIDS stage in HIV infection).The cause of death is respiratory failure with severe disruption of gas exchange.
Diagnosis of pneumocystosis
Preliminary diagnosis - clinical and epidemiological. Data on patient contact, identification of risk groups for HIV infection or other severe immunodeficiency are needed. There are also important features of the clinic - the absence of severe intoxication with respiratory syndrome.
The final diagnosis is carried out using laboratory-instrumental studies:
1) General blood test: pronounced leukocytosis( up to 20-30 * 109), increase in lymphocytes,
monocytes, eosinophils, moderate anemia - decrease in hemoglobin, ESR can be normal or alteredup to 50 mm / h.
2) Instrumental studies - radiography, according to which in the 1st stage of pneumocystosis there is an increase in pulmonary pattern, in the 2nd stage focal shadows appear that can be located on the right and on the left( there is also a one-sided lesion) alternating with areas of increased transparency( the so-called compensatory phenomenaemphysema) and strengthening of the vascular pattern - a syndrome of "veil" or "flakes of falling snow."
Pneumocystis pneumonia, radiologic picture
3) Parasitological studies aimed at detecting pneumocysts in the lesion focus.
To do this, take mucus from the respiratory tract with bronchoscopy( material - bronchoalveolar lavage), fibrobronchoscopy( prints), biopsies. The material can be obtained with the "method of cough induction": a preliminary 20-minute inhalation of hypertonic salt solution( 5% NaCl) is performed through the ultrasound inhaler, which leads to an increase in the production of mucus;then press on the root of the tongue with a spatula, a cough appears, and mucus is collected.
The diagnostic significance of mucus with the "cough induction method" is less than 70%, lavage is 70%, prints are 80-90%, biopsy material is 100%.The material is stained by Romanovsky-Giemsa and microscopized.
4) Serological tests for the detection of antibodies to pneumocysts in the blood - ELISA, NERF.
Paired sera taken at an interval of 10-14 days, in which only a rise in titer of 2 or more times serves as a confirmation of the disease. This is done to exclude normal carrier, antibodies are usually detected in 70% of the population.
5) PCR diagnostics to determine pneumocyst antigens in sputum, biopsy material, broncho-alveolar lavage.
Treatment of patients with pneumocystis pneumonia
1. Organizationally routine measures that include mandatory hospitalization of patients with severe clinical disease. The diet is balanced taking into account the condition of the patient.
2. Medical therapy includes etiotropic treatment( effect on the pathogen), pathogenetic( action on the links of pathogenic action of pneumocysts), symptomatic( elimination of symptoms of the disease).
- Etiotropic treatment is administered by intramuscular pentamidine IM once a day 4 mg / kg by a course on
for 10-14 days( however, only the doctor is required because of the toxicity of the drug);furazolidone 10 mg / kg / day;Trichopolum 25-30 mg / kg / day;Biseptolum 120 mg / kg / day first intravenously 3 times a day, then oral intake 2 times a day by a general course up to 3 weeks.
- For HIV-infected patients, antiretroviral therapy is prescribed, since PP in
of such patients occurs with a significant inhibition of immunity.
- Pathogenetic and symptomatic treatment includes anti-inflammatory drugs,
mucolytics, sputum-clearing preparations, expectorants;prevention of respiratory failure and the fight against its consequences.
Prevention of pneumocystosis
- To exclude intrahospital infection due to epidemic indications, medical personnel of children's institutions, oncological and hematological hospitals, child's homes and nursing homes should be examined.
- Medical prevention of risk groups. It can be primary( before the onset of the disease) and secondary( prevention of relapses).In HIV-infected patients, primary prevention is performed with a decrease in T-helpers( CD4 +) up to 300 cells / ml and preventive therapy with biseptol is administered inward to an adult 960 mg / day 2 r / day every 3 days for life. Secondary prophylaxis is performed with biseptol 480 in prophylactic doses.
- Timely detection and isolation of patients with pneumocystis pneumonia.
- Final disinfection in foci of pneumocystosis - wet cleaning with 5% chloramine solution.
Doctor infectious diseases Bykova N.I.