Pneumocystis carinii pneumonia



OVERVIEW

Definition.

Pneumocystis pneumonia (PCP) is an interstitial pneumonia caused by the proliferation of Pneumocystis carinii when the organism is immunosuppressed or impaired [1-3].

Pneumocystis is widely distributed in nature, in the lungs of humans and a variety of mammals, and was once thought to be a protozoa, once called Pneumocystis, and in recent years, it was found that the ultrastructure of Pneumocystis as well as its genes and encoded proteins are similar to those of fungi, and so it is categorized as a fungus.

Clinical manifestations include fever, dry cough, progressive dyspnea, etc. It mainly occurs in immunocompromised people and is especially common in AIDS patients [2-4].

Classification

According to the different clinical manifestations

Epidemic or classic type

In the early stage, it often manifests as sleep refusal, decreased appetite, low fever, diarrhea, and low weight.

In the later stage, shortness of breath, dry cough gradually appears and progressively worsens with dyspnea, nasal flaring, cyanosis, and sometimes splenomegaly may occur.

Disseminated or modern type

Initial manifestations include lack of appetite and weight loss.

This is followed by a dry cough, fever, cyanosis, dyspnea, and soon respiratory distress.

Pathogenesis

It is a common opportunistic infection and cause of death in patients with acquired immunodeficiency syndrome (AIDS), with a prevalence of 70% to 80%.

The disease is predominantly disseminated, and no population outbreaks have been reported.

There are no seasonal or gender differences in the incidence of Pneumocystis carinii pneumonia.

Causes

Causes

Pneumocystis carinii pneumonia is caused by infection with Pneumocystis carinii, and there are three basic conditions that lead to epidemics.

Infectious agents

The main sources of infection are patients and carriers of Pneumocystis carinii pneumonia.

Means of transmission

Airborne and droplet transmission are the main routes of transmission.

Susceptible people

Susceptible groups include patients with AIDS, lymphoma, leukemia, organ transplantation, and long-term use of immunosuppression.

High-risk groups

Mainly includes AIDS infected people and non-AIDS infected immunosuppressed people.

AIDS-infected patients: such as peripheral blood CD4+ T lymphocytes less than 200/μL patients, patients with high HIV viral load in plasma.

Non-AIDS-infected immunosuppressed population: e.g., tumor patients (e.g., lung cancer), organ transplant patients, other patients receiving immunosuppressive therapy, etc.

Symptoms

Common Symptoms

The clinical manifestations of patients with Pneumocystis pneumonia are mainly fever, dry cough, and dyspnea [1,3-5].

Fever

HIV-infected patients mainly present with low-grade fever; patients with moderate disease present with fever with or without sweating; and patients with severe disease present with persistent fever.

Dry cough

Involuntary cough mainly due to irritation of trachea and bronchial tubes, mostly characterized by cough without sputum.

Dyspnea

Dyspnea worsens after activity in mild patients; in moderate patients, dyspnea occurs after light activity; in severe patients, dyspnea occurs at rest.

Other symptoms

Some patients may be accompanied by cyanosis, chest pain, fatigue, and lethargy, but rarely hemoptysis.

Complications

Respiratory failure

Patients with Pneumocystis carinii pneumonia have a persistent dry cough and may develop respiratory failure in later stages when the disease continues to progress.

The main symptoms are cyanosis, coma, altered mental status, rapid heart rate, and elevated blood pressure.

Pneumothorax

Patients with Pneumocystis carinii pneumonia may cause gas to enter the pleural cavity resulting in pneumothorax.

It is mainly characterized by symptoms such as shortness of breath and sudden severe, sharp chest pain.

Interstitial Fibrosis

Pneumocystis carinii pneumonia is an interstitial lung disease. Late lesions damage the interstitium of the lungs, which may lead to destruction of the lung tissue structure, resulting in interstitial fibrosis.

The main signs are progressive dyspnea, pestle-like fingers/toes, dizziness, purple lips or nails, and limited mobility.

Consultation

Department of Medicine

Infection Medicine

People with a history of HIV infection or on immunosuppressive therapy are advised to consult a doctor promptly if they develop symptoms such as dyspnea, cyanosis, dry cough, or fever.

Respiratory medicine

If you develop an unexplained dry cough, fever, or respiratory distress, it is recommended that you consult a physician promptly.

Preparation for medical treatment

Consultation: Registration, Preparation of documents, Frequently Asked Questions

Tips for seeking medical treatment

If you have a fever before going to the doctor, keep track of the temperature change.

Preparation Checklist

Pay particular attention to the time of onset of symptoms, special behavior, etc.

Is there a fever? What is the temperature at the time of fever?

Is there a cough? Is the cough accompanied by phlegm? How long does each cough last?

Are there any symptoms of dyspnea? Duration of dyspnea? Does the dyspnea get worse?

Is there any chest pain or tightness? Is it relieved by rest?

Is there a history of HIV infection?

Are glucocorticoids or immunosuppressants used for a long time?

Has there been exposure to patients with Pneumocystis pneumonia?

Test results in the last 6 months, which can be carried to the doctor

Laboratory tests: routine blood test, blood gas analysis, serologic test, etc.

Imaging tests: chest X-ray, chest CT, etc.

Pathogenetic examination: sputum smear, etc.

Medication used in the last 3 months, if there is a medicine box or package, you can bring it to the doctor)

Antibiotics: compound sulfamethoxazole, caspofungin, ampicillin, clindamycin, pentamidine, etc.

Glucocorticoids: prednisone, etc.

Diagnosis

Diagnosis is based on

Medical history

The patient may have a history of AIDS, lymphoma, organ transplantation, long-term use of glucocorticoids or immunosuppressants, and leukemia.

Clinical manifestations

Patients may present with fever, dry cough, progressive dyspnea, and cyanosis.

Some patients may have nasal flaring.

A few scattered dry and wet rales may be heard in some patients.

Imaging

Imaging studies help to visualize changes within the lungs and may assist in the diagnosis.

OBJECTIVE: May assist in the diagnosis of Pneumocystis carinii pneumonia.

SIGNIFICANCE: Presents as a diffuse reticular nodular shadow starting at both lung hilums, with a gross glassy appearance, predominantly in both lower lungs. It may be completely normal in the early stages of the disease; in the late stages it appears as a hyperdense solid shadow.

Purpose: Helps detect lesions in patients with normal or atypical chest x-rays.

Significance: Early detection of lesions, which may have patchy, ground-glass, interstitial-type changes, or atypical manifestations such as limited or multiple nodular foci in the lungs, large lobar solid changes, pleural effusions, etc.

Precautions: Remove metal and other objects during the examination; prohibited for pregnant women.

Laboratory Tests

Purpose: Mainly used to indicate the presence of Pneumocystis carinii pneumonia in HIV-infected patients.

Significance: Elevated lactate dehydrogenase (>5000mg/L) often suggests the possible presence of Pneumocystis carinii pneumonia. A positive β-D-glucose test is also suggestive, and for HIV patients with co-infected Pneumocystis carinii pneumonia, their peripheral blood CD4+ T-cell counts are more often <200/μl.

Purpose: To help assess the condition of patients with Pneumocystis carinii pneumonia.

Significance: The main manifestation of hypoxemia, mild (PO2>70mmHg or alveolar arterial oxygen partial pressure difference <35mmHg), moderate (alveolar arterial oxygen partial pressure difference <45mmHg), severe (PO2<70mmHg or alveolar arterial oxygen partial pressure difference >45mmHg)

Precautions: Patients generally do not need to fast.

Specific antigen test: mainly detects specific antibody IgG or IgM, which is helpful for the early diagnosis of Pneumocystis carinii pneumonia and determining the prognosis. Immunofluorescence or immunohistochemical staining can be applied, with high sensitivity and specificity. The positive rate of serum G test is also high.

Serum specific antibody detection: commonly used methods include ELISA, indirect fluorescence test, immunoblotting test. Antibody titer more than 4-fold increment has diagnostic significance, and the positive rate is 50% to 90%.

Pathogenetic examination

Sputum smear:The positive rate of routine sputum examination is low, ranging from 6% to 30%.

Bronchoalveolar lavage fluid transbronchoscopic lung biopsy: BALF (bronchoalveolar lavage fluid) centrifuged sediment staining microscopy, the positive detection rate can be up to 79% ~ 89%.

Percutaneous lung puncture or open lung biopsy: limited to sputum and fiberoptic bronchoscopy negative, but the clinical high suspicion and must be further examination of the patient, obtaining specimens of the positive rate is higher.

PCR method: it can detect Pneumocystis carinii in sputum, bronchoalveolar lavage fluid, lung tissue biopsy specimens and serum/whole blood specimens with high sensitivity but low specificity.

Pathogen staining methods

Common staining methods include silver hexamine (GMS) stain, Giemsa stain, toluidine blue stain, and Diff-Quick stain.

Hexamine silver (GMS) staining is the best way to check the encapsulation; Giemsa staining is easy to operate, but the sensitivity is low; Toluidine blue staining and Diff-Quick staining can only shorten the staining time, but not improve the sensitivity.

Immunofluorescence technique is fast and convenient, and is gradually adopted, with high sensitivity, but there are false positives.

Nucleic acid test

Purpose: It can be used to detect lung tissue biopsy specimens, bronchoalveolar lavage fluid, sputum, oral gargle, etc. of immunosuppressed people.

Significance: The corresponding sequence of Pneumocystis carinii can be detected from the corresponding specimen.

Precautions: Patients who collect sputum or oral gargle should pay attention to keep their mouth clean.

Differential Diagnosis

Bacterial pneumonia

Similarity: Both may present with fever, cough and dyspnea.

Differences: Patients with bacterial pneumonia often have an acute onset of illness and cough with sputum; patients with Pneumocystis carinii pneumonia often have a slower onset of illness and a dry cough without sputum, which is usually not persistent, and progressive dyspnea is often present. Pathogen testing may assist in differentiation.

Chlamydia pneumonia

Similarities: May present with fever, dry cough, etc.

Difference: patients with chlamydia pneumonia have positive serum chlamydia pneumonia antibody or positive nucleic acid test, which can be differentiated from Pneumocystis carinii pneumonia, and special tests such as pathogen isolation and serologic testing can assist in the diagnosis.

Tuberculosis

Similarity: manifested by fever, cough and other symptoms.

Differences: In tuberculosis, coughing is often accompanied by sputum with blood in the sputum, coughing and sputum can last for more than two weeks, and fever is mostly afternoon flashes; in Pneumocystis carinii pneumonia, coughing is often without sputum, and fever is usually independent of the time of the day.

Treatment

Aim of treatment: kill the pathogen, improve the lung and systemic symptoms.

Treatment principle: Drug treatment is the mainstay, combined with the actual condition of the patient, to develop an individualized program. For patients with underlying diseases, targeted treatment of the primary underlying disease is also required.

General treatment

Bed rest, give oxygen, improve ventilation function.

If dyspnea progressively worsens, artificial assisted respiration can be given.

Strengthen supportive therapy to maintain water and electrolyte balance.

Medication

Antibiotics

Antibiotics are the preferred therapeutic drugs [4,6-8].

It has the advantages of high efficiency and low price.

They mainly play a role in killing Pneumocystis carinii by interfering with the metabolism of folic acid.

It is administered orally to mild and moderate patients and intravenously to severe patients.

The drug has adverse reactions such as fever, rash, leukopenia, liver damage, hyperkalemia and azotemia.

It is indicated for severely ill patients, and the addition of caspofungin may be considered if the general condition is extremely severe and poor.

The usual course of treatment is 14 days.

The drug may cause adverse reactions such as rash, pruritus, hepatitis, and hepatic insufficiency.

It needs to be used in combination with methotrexate, which is commonly used in the former.

It is mainly indicated for mild to moderate patients.

The drug has adverse reactions such as rash, fever, methemoglobinemia, hemolysis.

It is mainly applicable to mild to moderate patients.

The drug has adverse reactions such as methemoglobinemia, hemolysis, rash, diarrhea, and fever.

It is indicated for patients who are critically ill and intolerant to cotrimoxazole, or for whom cotrimoxazole therapy is not effective.

The drug has adverse reactions such as azotemia, pancreatitis, abnormal blood glucose, and granulocyte deficiency.

Glucocorticoid

For patients with moderately severe Pneumocystis carinii pneumonia (PaO2 < 70 mm Hg or alveolar-arterial oxygen partial pressure difference > 35 mm Hg).

Helps to improve hypoxemia, reduce pulmonary fibrosis, and decrease morbidity and mortality.

The drug may have adverse effects of Cushing’s syndrome such as centripetal obesity and purplish skin; gastrointestinal symptoms such as gastritis and gastric ulcers.

It is indicated for patients with moderately severe Pneumocystis pneumonia.

Early application helps some patients to be exempted from the use of ventilators and reduces the morbidity and mortality rate.

The drug may have adverse reactions such as infection, metabolic acidosis, convulsions, insomnia, abdominal pain.

Ventilator-assisted respiration

It is mainly used in patients with progressive exacerbation of dyspnea and inability to maintain normal oxygen saturation.

Attention should be paid to the airway care of patients, timely adjustment of ventilator parameters, and detection of patients’ blood gas indexes.

The course of Pneumocystis carinii pneumonia is generally 21 days, in the course of treatment should be timely review of chest X-ray or CT, if the lesion is obviously absorbed, the course of treatment can be changed to prophylaxis, if the lesion is still no obvious improvement, should continue to treat, and at the same time, should be excluded from the combination of other opportunistic infections.

Anti-HIV therapy

The CD4+ T-cell counts of PCP patients are all <200 cells/μl, so the appropriate time to start anti-HIV therapy should be chosen, but the superimposition of drug toxicity should be prevented.

For patients with fair general condition and significant improvement after anti-PCP treatment, antiretroviral therapy can be started as early as possible, usually within 2 weeks of anti-PCP. However, it should be withheld in patients in poor general condition.

Prognosis

Cure

The case fatality rate of PCP approaches 100% if untreated. Early antifungal therapy is effective in reducing the morbidity and mortality of patients [4].

AIDS patients

In patients with AIDS, the morbidity and mortality rate can be reduced to less than 15% with aggressive antipneumocystis treatment; however, the morbidity and mortality rate associated with respiratory failure in patients with severe Pneumocystis infections can still be as high as 60%.

Non-AIDS patients

Pneumocystis carinii disease in non-AIDS patients has a mortality rate of up to 40%, even after treatment.

Prognostic Factors

The following factors may lead to a worse prognosis for patients with this disease, especially in patients with AIDS/HIV, and are known as poor prognosis-related factors [13].

Increasing age.

Previous diagnosis of PCP.

Presence of cytomegalovirus in bronchoalveolar lavage fluid.

Elevated serum lactate dehydrogenase concentration.

Low CD4 cell count.

Hazards.

Patients with Pneumocystis carinii pneumonia may develop life-threatening respiratory failure if not treated promptly.

Pneumocystis pneumonia is contagious and may infect family members as well as those around them.

Daily

Daily Management

Dietary management

Balanced nutrition, eat more high-quality protein, foods rich in vitamins and trace elements, such as dairy products and lean meat.

Psychological support

Receive health education, communicate more with friends and relatives, and maintain a good state of mind.

Let the patient’s family understand the disease and help the patient to enhance the confidence in fighting the disease.

Life management

To avoid overwork, ensure sufficient sleep and adequate rest.

Personal Management

Pay attention to indoor ventilation and maintain hand hygiene.

Use daily necessities exclusively to avoid cross-infection.

Follow-up and review

Regular review of chest X-ray and chest CT is recommended to observe the progress of the disease and the effect of treatment.

Prevention

There is no vaccine to prevent this disease, but it may be reduced by the following measures [12].

For patients with confirmed Pneumocystis carinii pneumonia, respiratory isolation should be carried out to avoid nosocomial cross-infection, and the wards should be well ventilated and disinfected.

The choice of maintenance immunosuppression regimen should be individualized to avoid excessive immunosuppression, which is the key to preventing the disease.

For high-risk groups such as non-HIV-infected or HIV-infected patients using immunosuppressants for a long time, prophylactic medications such as cotrimoxazole should be used, and attention should be paid to taking them in accordance with the doctor’s instructions [9-10].