Presentation on theme: "By:. Nouf Al-Harthy... Tuberculosis.. Tuberculosis (abbreviated as TB for tubercle bacillus or Tuberculosis) is a common and deadly infectious disease."— Presentation transcript:
By:. Nouf Al-Harthy..
Tuberculosis.. Tuberculosis (abbreviated as TB for tubercle bacillus or Tuberculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. Tuberculosis most commonly attacks the lungs (as pulmonary TB) but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, bones, joints and even the skin. Other mycobacteria such as Mycobacterium bovis, Mycobacterium africanum, Mycobacterium canetti, and Mycobacterium microti can also cause tuberculosis, but these species do not usually infect healthy adults..
In the past, tuberculosis was called consumption, because it seemed to consume people from within, with a bloody cough, fever, pallor, and long relentless wasting. Other names included phthisis (Greek for consumption) and phthisis pulmonalis; scrofula (in adults), affecting the lymphatic system and resulting in swollen neck glands; tabes mesenterica, TB of the abdomen and lupus vulgaris, TB of the skin; wasting disease; white plague, because sufferers appear markedly pale; king's evil, because it was believed that a king's touch would heal scrofula; and Pott's disease, or gibbus of the spine and joints. Miliary tuberculosis now commonly known as disseminated TB– occurs when the infection invades the circulatory system resulting in lesions which have the appearance of millet seeds on X-ray.
Symptoms When the disease becomes active, 75% of the cases are pulmonary TB chest pain coughing up bloodand a productive, prolonged cough for more than three weekssymptoms Fever chills night sweats appetite loss weight loss Pallor often a tendency to fatigue very easily.
Symptoms Extrapulmonary infection sites include the pleura the central nervous system in meningitis the lymphatic system in scrofula of the neck the genitourinary system in urogenital tuberculosis bones and joints in Pott's disease of the spine
Bacterial species The primary cause of TB, Mycobacterium tuberculosis (M. TB), is an aerobic bacterium that divides every 16 to 20 hoursMycobacterium tuberculosis it is classified as a Gram-positive bacterium MTB is a small rod-like bacillus the bacterium can grow only within the cells of a host organism, but M. tuberculosis can be cultured in vitro MTB retains certain stains after being treated with acidic solution, it is classified as an acid-fast bacillus The most common staining technique, the Ziehl-Neelsen stain, dyes AFBs a bright red that stands out clearly against a blue background. Other ways to visualize AFBs include an auramine-rhodamine stain and fluorescent microscopy.Ziehl-Neelsen
Transmission When people suffering from active pulmonary TB cough, sneeze, speak, kiss, or spit, they expel infectious aerosol droplets 0.5 to 5 µm in diameter. A single sneeze, for instance, can release up to 40,000 droplets Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very low and the inhalation of just a single bacterium can cause a new infection People with prolonged, frequent, or intense contact are at particularly high risk of becoming infected, with an estimated 22% infection rate. A person with active but untreated tuberculosis can infect 10–15 other people per year Others at risk include people in areas where TB is common who residents and employees of high-risk congregate served and low-income populations,high-risk, children exposed to adults in high-risk categories, patients immunocompromised by conditions such as HIV/AIDS, people who take immunosuppressant drugs, and health care workers serving these high-risk clients.immunocompromisedHIVAIDS
transmission The probability of transmission from one person to another depends upon the number of infectious droplets expelled by a carrier, the effectiveness of ventilation, the duration of exposure, and the virulence of the M. tuberculosis strain The chain of transmission can therefore be broken by isolating patients with active disease and starting effective anti-tuberculous therapy. After two weeks of such treatment, people with non- resistant active TB generally cease to be contagious
Pathogenesis TB infection begins when the mycobacteria reach the pulmonary alveoli, where they invade and replicate within alveolar macrophages The primary site of infection in the lungs is called the Ghon focus. Bacteria are picked up by dendritic cells, which do not allow replication, although these cells can transport the bacilli to local (mediastinal) lymph nodes. Further spread is through the bloodstream to the more distant tissues and organs where secondary TB lesions can develop in lung apices, peripheral lymph nodes, kidneys, brain, and bone All parts of the body can be affected by the disease, though it rarely affects the heart, skeletal muscles, pancreas and thyroid
Pathogenesis Tuberculosis is classified as one of the granulomatous inflammatory conditionsgranulomatous . Macrophages, T lymphocytes, B lymphocytes and, with fibroblasts are among the cells that aggregate to form a granuloma lymphocytes surrounding the infected macrophages. The granuloma functions not only to prevent dissemination of the mycobacteria, but also provides a local environment for communication of cells of the immune system. Within the granuloma, T lymphocytes (CD4+) secrete cytokines such as interferon gamma, which activates macrophages to destroy the bacteria with which they are infectedT lymphocytes (CD8+) can also directly kill infected cells.
Pathogenesis Another feature of the granulomas of human tuberculosis is the development of cell death, also called necrosis, in the center of tubercles. To the naked eye this has the texture of soft white cheese and was termed caseous necrosis.caseous If TB bacteria gain entry to the bloodstream from an area of damaged tissue they spread through the body and set up many foci of infection, all appearing as tiny white tubercles in the tissues. This severe form of TB disease is most common in infants and the elderly and is called miliary tuberculosisTissue destruction and necrosis are balanced by healing and fibrosis Affected tissue is replaced by scarring and cavities filled with cheese-like white necrotic material. During active disease, some of these cavities are joined to the air passages bronchi and this material can be coughed up. It contains living bacteria and can therefore pass on infection
Diagnosis Tuberculosis can be a difficult disease to diagnose, due mainly to the difficulty in culturing this slow-growing organism in the laboratory A complete medical evaluation for TB must include a medical history, a chest X-ray, and a physical examination. Tuberculosis radiology is used in the diagnosis of TB. It may also include a tuberculin skin test, a serological test, microbiological smears and cultures., New TB tests are being developed that offer the hope of cheap, fast and more accurate TB testing. These use polymerase chain reaction detection of bacterial DNA and antibody assays to detect the release of interferon gamma in response to mycobacteria
TP in a Saudi Arabian Hospital Mycobacterium tuberculosis is a major cause of morbidity and mortality throughout the world. The number of cases of tuberculosis showed an initial decline in the United States The reversal of the downward trend was due to multiple factors, including the AIDS epidemic and the emergence of drug resistance. Drug resistance of M tuberculosis also shows marked geographic variation from one country to the other and ranges from 0 to 18% In Saudi Arabia, the pattern of resistance of M tuberculosis also shows marked regional variation.3 There is only one published study4 about the prevalence of drug resistance of tuberculosis in the Eastern Province of Saudi Arabia.34
Materials and Methods All pulmonary and extrapulmonary tuberculosis patients with positive culture results from January 1989 to December 2003 were included in the study. The medical records were reviewed for the age, sex, nationality, and the site of the culture. Cultures were performed at the mycobacteriology laboratory of the Saudi Aramco Medical Services Organization using the conventional Lewes-Johnson media. M tuberculosis was isolated by standard procedures M tuberculosis complex was identified by conventional biochemical tests. Antimycobacterial sensitivity testing was done by the disk method as described by Wayne and Krasnow
Results Of the total patients, there were 236 Saudis (84.6%), and the remaining 43 patients (15.4%) were non-Saudis. Of the non-Saudis, 19 were Philippinos, 10 were Indian, 1 was Sir Lankan, 3 were Indonesians, 5 were European, 3 were Pakistani, 1 was Lebanese, and 1 was Canadian. Of the total patients, 133 were male (47.7%) and 146 were female (52.3%). The age range was to 89 years (mean age ± SD, 49 ± 20 years). The isolates were obtained from pulmonary specimens, 49%) and extrapulmonary sites The source of four isolates could not be identified. The majority of the extrapulmonary isolates were obtained from lymph nodes (95 of 135 isolates, 70%). The other extrapulmonary sites include bone and joints peritoneum/ascetic fluid urine gastric aspirates and skin ulcers
Discussion The prevalence of TB in dialysis patients is closely related to, and several times higher than, its prevalence in the general population In the present study, the prevalence of TB in dialysis patients in different regional hospitals varied from 2.4 to 14.5% In a survey of TB in Saudi Arabia using positive Mantoux test as the indicator, the mean annual risk was estimated to be 0.56% The reasons for differences in the prevalence of Tb in dialysis patients in different regions of Saudi Arabia are not clear. The highest prevalence (14.5%) has been reported from the Security Forces Hospital in the Central Province. The likely explanations would be the higher index of suspicion and the more sophisticated and invasive methods used to diagnose Tb in the regions with higher prevalence. Al Kassimi in an epidemiological study of TB in Saudi Arabia found the annual risk of infection of 0.5% in Riyadh to be similar to rest of the country
Treatment Treatment for TB uses antibiotics to kill the bacteria. The two antibiotics most commonly used are rifampicin and isoniazid. However, instead of the short course of antibiotics typically used to cure other bacterial infections, TB requires much longer periods of treatment (around 6 to 12 months) to entirely eliminate mycobacteria from the body.rifampicinisoniazid Drug-resistant TB is a public health issue in many developing countries, as treatment is longer and requires more expensive drugs. Multi-drug resistant TB (MDR-TB) is defined as resistance to the two most effective first line TB drugs: rifampicin and isoniazid. Extensively drug-resistant TB (XDR- TB) is also resistant to three or more of the six classes of second-line drugs.[ rifampicin[
Prevention TB prevention and control takes two parallel approaches. In the first, people with TB and their contacts are identified and then treated. Identification of infections often involves testing high- risk groups for TB. In the second approach, children are vaccinated to protect them from TB. no vaccine is available that provides reliable protection for adults.vaccine However, in tropical areas where the incidence of atypical mycobacteria is high, exposure to nontuberculous mycobacteria gives some protection against TB nontuberculous mycobacteria