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lec 6
vi sinh
| M. tuberculosis complex and M. leprae | - They are unable to replicate in the environment - They are found only in humans (and other warmblooded animals) |
| NTM | - Free-living saprophytic (hoại sinh) environmental - Some may be found in humans |
| Mycobacterium tuberculosis have | • Slim, slightly curved or straight (*) • Non-motile • High lipid content in the cell wall - Acid-fast positive • Obligate aerobic |
| M. leprae | does not grow in vitro |
| Special Gram-positive bacilli: Mycobacterium tuberculosis | Three groups - M. tuberculosis complex - M. leprae - "Non-tuberculous mycobacteria (NTM)" |
| Mycobacterium tuberculosis Cell wall structure | High content of lipids form a coat that makes them hard, impermeable (không thấm), and hydrophobic (kỵ nước) >> Acid fastness - Mycolic acids - Lipoarabinomannan (LAM) - Other glycolipids |
| Tuberculosis | Caused by Mycobacterium tuberculosis complex Is a chronic granulomatous disease High mortality rate in untreated disease TB Person-to-person transmission |
| Mycobacterium tuberculosis complex are | - M. tuberculosis • The most common and important • Only found in humans - M. bovis (trực khuẩn lao bò) - M. africanum • Found in Africa |
| one of the most common communicable diseases in Viet Nam | Tuberculosis |
| Latent TB Infection | Inactive, bacteria are under control in the body TST or IGRA results positive Chest x-ray usually normal Sputum smears and cultures negative No symptoms Not contagious (truyền nhiễm) Not a case of TB |
| TB Pulmonary Active Disease | Active, multiplying bacteria in the body TST or IGRA results positive Chest x-ray usually abnormal Sputum smears and cultures may be positive Symptoms: cough, fever, weight loss Often contagious before treatment A case of TB |
| Risk factors of TB | - HIV co-infection (đồng nhiễm) is the most important Age: Highest during late adolescence and early adulthood - Also in the elderly |
| Tuberculosis is require a | Th1 cellular immune response for their contro |
| Immunological tests | are used for the diagnosis of latent infection |
| The purpose of testing for latent tuberculosis infection is | To identify individuals who are at increased risk for the development of tuberculosis disease |
| Tuberculin skin test (TST) Using "tuberculin purified protein derivative" (PPD) | A positive PPD skin test only means past exposure (đã từng tiếp xúc) to MTB • It cannot differentiate between latent or active disease |
| TST Disadvantages | • False positives - Infections with another mycobacterial species - Prior BCG vaccination • False negatives - Patients with severe disseminated disease - Immunosuppressed |
| BCG vaccination | is a live strain of M. bovis developed by Calmette and Guérin in 1921 is the most widely administered vaccine in the world Benefits • Lower risk of TB meningitis and disseminated disease in children • Better in small children than older children and a |
| Anaerobic Gram-positive bacilli: Clostridium | • Large Gram-positive bacilli • Obligately anaerobic (some are aerotolerant anaerobes) • Spore-forming, similar to Bacillus - Endospore form - Vegetative form survive in the environment as endospores Virulence is caused by the production of potent e |
| Clostridium perfringens | - Environment • Soil, water - Intestinal tract of humans and animals • They produced many different potent exotoxins |
| Clostridium perfringens Diseases • Soft-tissue infections | - Cellulitis - Muscles infections • Without necrosis: Suppurative myositis • With necrosis: Myonecrosis (Gas gangrene) - Painful - Systemic spread - High mortality |
| Clostridium perfringens Diseases • Enteric infections | - Food poisoning: Mild watery diarrhea - Necrotizing enteritis • Rare but severe • Necrosis of jejunum: Abdominal pain, vomiting, bloody diarrhea, .. |
| Severe C. difficile disease following antibiotic exposure in an immunocompromised patient | 60-year-old man - Who received a transplanted liver 5 years ago • He is admitted to hospital admission for evaluation of abdominal pain and severe diarrhea • Three weeks prior to admission he received a 10-day course of oral trimethoprim-sulfamethoxazol |
| Clostridium difficile | is the most common cause of antimicrobial-related diarrhea Acquired by the fecal-oral route |
| Clostridium difficile Virulence | Host factors: Normal flora Bacterial factors: Two potent exotoxins |
| Clostridium botulinum | The cause of botulism Ubiquitous - Vegetables, fruits, seafood, soil and marine (biển) |
| Botulinum toxin | - The most potent bacterial toxin, and perhaps the most potent known poison - It causes flaccid paralysis (gây tê liệt) |
| Food-borne botulism | Home canned foods Intoxication by ingestion of food contaminated by preformed botulinum toxin |
| Clostridium botulinum Treatment | Antitoxin Antimicrobials: Penicillin G |
| Clostridium tetani (uốn ván) | The cause of tetanus Toxins - Tetanospasmin ('tetanus toxin') • The most important virulence factor |
| Clostridium tetani Pathogenesis. | Inoculation of spores through damaged skin > Vegetative form > Production of tetanospasmin Absorption of the toxin (hấp thụ độc tố) > Retrograde axonal transport (vận chuyển ngược)> Spinal cord and brainstem |
| "A" subunit | is toxic - It inhibits the release of the inhibitory neurotransmitters (ức chế sự giải phóng các chất dẫn truyền thần kinh) (Glycine and GABA) > Excitation of motor neurons (tb thần kinh kích thích vận động) > It causes spastic paralysis (gây tê liệt) |
| Generalized Tetanus | The most common The most severe Cause: - Stiff neck - 'Risus sardonicus' (sardonic smile) - Rigid abdomen |
| Localized Tetanus | Rare Many times will become generalized tetanus Tonic and spastic muscle contractions (co thắt cơ bắp) in one extremity or body region |
| Neonata Tetanus | Failure in asepsis (vô trùng) in managing the umbilical stump (cuống rốn) if mothers are not well immunized |
| Previous doses of Tetanus vaccine for Clean, minor wound | <3 (doses): Vaccination NOT use HTIG >=3: Vaccination only if last dose given >=10 years |
| Previous doses of Tetanus vaccine for All other wounds | <3 (doses): Vaccination & HTIG >=3: Vaccination only if last dose given >=5 years |
Created by:
huy12345
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