OVERVIEW
Human Immunodeficiency Virus Infection AIDS (HIV/AIDS) patients due to the HIV virus attack its immune function has been destroyed, often accompanied by a variety of opportunistic infections, among these opportunistic infections, tuberculosis is one of the most common opportunistic infections of AIDS, tuberculosis and AIDS are mutually promote the progress of the lesion, deterioration, and rapidly lead to the patient’s death of the accompanying disease. HIV-positive patients infected with tuberculosis bacteria is higher than the HIV-negative patients. Patients infected with tuberculosis bacilli have a 30-fold higher incidence of tuberculosis than HIV-negative individuals. Existing studies show that the rate of dual infection with TB within 9-12 years after infection with immunodeficiency virus is close to 8%, and the death rate of patients with dual infection is as high as 1/3, which is much higher than the incidence of TB in the general population.
Etiology
AIDS is the main cause of tuberculosis.
1. Endogenous resurgence
HIV infection can cause potentially old TB foci in the body that had been stabilized to become reactivated and secondary TB disease occurs.
2. Exogenous reinfection
Due to the low immunity of the body, HIV patients are prone to outbreaks of multidrug-resistant tuberculosis and reinfection with tuberculosis bacilli, and soon develop and deteriorate.
3. Primary infection
Mostly occur in countries and regions with very low tuberculosis epidemic, HIV-infected patients can develop primary tuberculosis.
The onset of AIDS is mainly due to HIV infection, HIV virus in the T lymphocyte CD4 + cells in a large number of replication, so that its cell function is seriously damaged and destroyed, resulting in the infected organism immunodeficiency or even due to the occurrence of multiple organ failure triggered. After the human body is infected with HIV, it is extremely difficult to get rid of HIV in the body, and the human immune system is damaged by the continuous replication of HIV, which especially leads to the reduction of the absolute number of CD4+ cells, resulting in a great increase in the likelihood of the human body being infected by opportunistic infections. Research has found that the infection rate of Mycobacterium tuberculosis (MTB) in HIV-infected patients is as high as 58.8%, and after HIV-positive patients are infected with MTB, it is very easy for MTB to multiply and spread rapidly in the body of the infected patients to the extent that it affects multiple organs of the infected patients, and it is easy for the inactive tuberculosis foci of the infected patients to get recurrent; research has shown that more than 9% of the HIV-positive patients have double infections of pulmonary tuberculosis and HIV. Studies have shown that TB-HIV co-infection is present in more than 9% of HIV-positive patients. Mycobacterium tuberculosis infection can exacerbate the course of HIV infection: ① the mononuclear cells of tuberculosis patients, the susceptibility to HIV infection is increased. ② After the organism is infected with Mycobacterium tuberculosis, it can induce the release of gamma interferon, interleukin 1 (IL-1), IL-2, tumor necrosis factor and other cytokines, which can enhance the replication of HIV. (iii) The main component of M. tuberculosis cell wall, arabinomannan, is a potent inducer of HIV replication. (iv) M. tuberculosis and pure protein derivatives can induce enhanced RNA expression and increased P24 production of HIV in monocytes.
HIV infection can influence the natural history of TB, and similarly TB influences the course of HIV infection. For example, activation of CD4 lymphocytes in HIV-infected individuals by Mycobacterium tuberculosis can promote HIV viral replication. Clinically, there is a direct relationship between the number of CD4 cells and the clinical manifestations of TB. In HIV-uninfected individuals with TB, CD4 cell counts are high (>300×106/L), and the lungs show typical TB lesions, with early foci located in the upper lobes of the lungs, with or without cavity formation.After HIV co-infection with TB, the CD4 cell counts decrease, and the lesions show a disseminated pattern, spreading to the two lungs or to other organs throughout the body. The lungs may show different degrees of interstitial infiltration, with some showing progressive primary tuberculosis, enlarged hilar lymph nodes, and infiltration of the lower lobes of the lungs. Some patients are susceptible to bacteremia when they have a CD4 cell count of 6/L, and the chance of bacteremia is significantly higher with a CD4 cell count of 6/L.
Symptoms
HIV-infected patients, once they come into contact with a TB patient who has expelled the bacteria, are susceptible to TB infection, which rapidly worsens and spreads. Symptoms in TB patients infected with HIV become apparent and rapid and are more frequent than in HIV-uninfected persons.
Tuberculosis can develop at any time during the course of HIV/AIDS. Due to the different immunosuppressive ability, age, and other infectious agents of the patients, the clinical manifestations are very different, and the accompanying tuberculosis is most commonly found in the lungs. In addition to the common symptoms such as coughing, coughing up sputum, dyspnea, and chest pain, there are also the symptoms of common tuberculosis such as fever, night sweats, anorexia, and weight loss. In addition, a small number of patients also experience clinical symptoms such as high fever and respiratory distress. After synthesizing the results of the current study, the clinical features of AIDS-associated tuberculosis mainly include:
(1) High acute morbidity and rapid progression of the disease. The acute cases are mainly granulomatous and exudative lesions. After AIDS patients are infected with Mycobacterium tuberculosis, Mycobacterium tuberculosis tends to spread rapidly in the patients’ bodies, and it is very easy to activate the inactive foci in their bodies, which then destroys the pulmonary veins and lymphatics and spreads to the whole body.
(2) Increased complications of opportunistic infections. Patients are prone to chronic infectious diarrhea, oral and esophageal fungal infections, pulmonary infections, gastric hemorrhage, anal acromegaly and other infectious diseases.
(3) Low sputum culture positivity rate and low tuberculin positivity rate. In the early stage of tuberculosis infection, sputum antacid bacilli positivity rate is higher, sputum smear positivity rate is 31%~89%; CD4+ cell count >200/mm3, PPD test is positive, while most patients have entered the middle or late stage when examined, sputum smear is mostly negative, CD4+ cell count is decreasing rapidly, and the result of PPD test is also mostly negative.
(4) Long disease duration, poor prognosis and high mortality rate. Compared with simple tuberculosis, the incidence of drug-resistant tuberculosis strains is very high in patients with AIDS-associated tuberculosis, and the anti-TB treatment and anti-HIV treatment will have certain constraints and affect the therapeutic effect, and even promote the rapid deterioration of both conditions, so the disease duration is long, the prognosis is poor, and the mortality rate is high.
(5) There are many complications of blood-borne diseases, most of which are viral hepatitis such as hepatitis B and hepatitis C. Especially, the incidence rate of male injecting drug users is the highest.
Tests
1. HIV test
At present, there are more than 100 methods to detect HIV, which can be categorized into antibody test and virus test.
2. Chest imaging
AIDS associated with tuberculosis shows diversified manifestations on imaging, and its imaging characteristics are mainly:
(1) The lesions are widely distributed. Simple pulmonary tuberculosis mostly occurs in the posterior segment of the upper lung lobes or the dorsal segment of the lower lung lobes, and the scope of the lesions is mostly confined to one to two lobes; whereas the lesion site of AIDS-associated pulmonary tuberculosis can be anywhere in the patient’s lungs, and the lesions in the lungs show the characteristics of single-lung or double-lung multiple distribution, and they are the lesions of multiple lobes and segments of the lungs, and the single lobe involvement is very rare, with the most significant distribution of the lesions being the diffuse distribution of both lungs and the distribution of the middle and upper lungs, and the most significant distribution in both lungs, and the most significant distribution in both lungs. Among them, the diffuse distribution in both lungs and the distribution in the middle and upper lungs were the most significant, and there was no obvious difference in the distribution position in both lungs.
(2) Various lesion patterns: The lesion patterns of AIDS combined with tuberculosis mainly include: patchy, flaky, large and small nodules, streaks, pleural effusion, or millet, cavities, calcification, and enlarged mediastinal lymph nodes, etc., which can appear individually or together in a single case, and the majority of the patients’ CT data often show multiple lesion patterns or are accompanied by more pleural and pericardial effusions. In most patients, the CT data often show multiple lesions or with pleural and pericardial effusion, and a small number of patients have images of striations, cavities, or calcifications, etc. The CT images show that the edges of the solid lesions or patchy lesions are clear, and the enhancement of the lesions is either uniform or uneven.
(3) The number of cavities increases as the disease deteriorates, and the number of small cavities in the lesions of patients with AIDS with tuberculosis is usually located in the center of nodules or parenchymal shadows, with smooth inner walls, and increases as the disease deteriorates. The incidence of cavities in patients with TB in the later stages of the disease was significantly higher than that in patients in the early stages, and most of the cavities occurred in the upper and middle lobes of the lungs or even in the lower lobes of the lungs, and most of them were wall-less cavities with irregular inner walls.
(4) The incidence of hilar and mediastinal lymph node enlargement is very high, and CT enhancement scans show irregular ring-like enhancement in most lesions, with caseous necrotic foci in the center of the lesion, but there are not many typical tuberculosis foci, and the proportion of mediastinal lymph node enlargement and pleural effusion cases is high. The reason for this may be the decrease in cellular immunity, which makes it easy for tuberculosis bacteria to infect the mediastinal lymph nodes, leading to the enlargement of the lymph nodes. Compared with patients with simple pulmonary tuberculosis, the incidence of enlarged hilar and mediastinal lymph nodes is significantly higher.
(5) Extrapulmonary tuberculosis occurs more often, mainly manifesting as enlargement of superficial lymph nodes or parietal mesenteric and retroperitoneal lymph nodes, and splenic tuberculosis occurs in a small number of patients.
(6) The number of patients with pleural effusion increased. It is mainly manifested as unilateral or bilateral effusion of moderate or lower level.
(7) Milky lesions are more common. They may be caused by blood dissemination triggered by cornified tuberculosis or primary lesions in the lungs.
(8) Parenchymal lesions are not very dense. The CT of HIV-associated tuberculosis often shows light exudative lesions with a flaky density, with fewer fibroplastic, calcified foci and cavitary lesions, compared with simple tuberculosis lesions with a high density, clearer border patches, and common fibroplastic, calcified foci and cavitary lesions, which to some extent indicates that there may be a difference in the immune status of the two.
3. Tuberculin test
HIV-infected patients with tuberculosis have a higher tuberculin positivity rate, while AIDS patients with tuberculosis have a lower tuberculin positivity rate; sputum positivity rate is also low.
Diagnosis
The diagnosis of HIV depends mainly on the detection of the pathogen. Respiratory secretion smear detection rate is very low, can ultrasonic nebulization sputum guide examination. The detection rate of pathogen precipitated by ciliary bronchoscopy lavage is 60%～80%, and the positive rate of bronchoalveolar lavage or biopsy specimen via ciliary bronchoscopy can reach 90%. If necessary, percutaneous lung puncture or thoracic lung biopsy to clarify the diagnosis. Diagnosis can be made in patients with confirmed HIV infection or AIDS accompanied by the aforementioned clinical, X-ray and laboratory data.
Bacteriologic testing, in 1989, was recommended by the CDC for routine HIV screening of all patients with tuberculosis. Traditional bacteriological examination of sputum specimen is still the most accurate method to diagnose tuberculosis, but only open tuberculosis can be detected, and when the bacilli are few, it still cannot be detected, and the sensitivity and specificity of detection are not high, so it is not recommended to be used for HIV-infected patients. 2000 reported the microscopic observation of the drug-sensitive method of sputum tuberculosis bacteria cultured in liquid medium, which can detect the characteristic cord factor at the early stage of MTB growth, and can detect multi-drug-resistant (MDR) bacteria, and can be used to detect MDR patients. It was reported in 2000 that the microscopic observation drug sensitization method of culturing sputum M. tuberculosis in liquid medium could detect characteristic sordid factors at the early stage of MTB growth, and could detect multidrug-resistant tuberculosis.
Treatment
Effective treatment and control of TB remains central and prioritized when developing treatment strategies for HIV/AIDS patients with co-infection with TB, which is a significant cause of death in HIV-infected patients. The treatment of mixed infections is complicated by the fact that some antiretroviral and anti-TB drugs have serious interactions with each other, which can increase the toxicity of the anti-TB drugs or decrease the metabolic levels of the antiretroviral drugs. In principle, once tuberculosis is diagnosed, anti-TB DOT treatment should be given, and antiretroviral treatment should be delayed until anti-TB treatment is completed.