M8: TB and Respiratory Pathogens Flashcards
What is TB?
- A granulomatous infectious disease caused by Mycobacterium tuberculosis
- Aggregation of macrophages with lymphocytes and some plasma cells
What are some symptoms of TB?
- Persistent cough (blood in sputum)
- Fatigue
- Chest pain
- Loss of apetite
- Weight loss
- Fevers and night sweats
- Chills
What are some oral manifestations of TB? (4)
- Ulcer on tongue
- Nodules
- Periapical granulomas
- Indurated patches (hard patches)
Give some features of mycobacteria (5)
- Aerobic
- Curved/straight rods
- Non-motile
- Acid-fast
- Causes TB
How can a Ziehl-Neelsen stain determine TB?
- TB is acid-fast
- Acid-fast cells appear red on a green background during this stain
- Where as non acid-fast cells remain green
How do we grow acid fast bacilli?
On Lowenstein-Jensen (LJ) slope
How long till growth of TB bacilli is visible on a LJ slope?
What is their appearance like?
- Colonies visible to eye in approx. 8 weeks
Colonies typically ‘rough, buff and tough’
How can rapid detection of M. tuberculosis carried out? (2)
- Direct staining of sputum smear and identification
- Nucleic acid amplification techniques (ie PCR)
What is the pathogenesis of TB?
- M. tuberculosis survives in alveolar macrophages
- Which causes a cell mediated immune response
- Clinical features of TB due to immune response mediated tissue destruction
What occurs during primary TB?
- Initial infection occurs
- Primary complex produced, as well as potential additional foci and spread to other organs
- After about 10 day of primary complex macrophages and T-lymphocytes produced
- Granuloma produced (caseation)
- Reaction causes post primary disease
What occurs during post-primary TB?
- Primary complex resolves
- Months/years later reactivation of dormant foci is lobes of the lungs occur
- Large granulomas with caseation occur
- Further spread of and lesions occur
TB reaction is likely with who? (3)
- Elderly
- Transplant patients
- HIV patients
What type of TB patients are infectious?
Only sputum positive patients are infectious
How is Human TB transmitted?
Inhalation in cough droplets from ‘open’ individuals
What vaccination can help prevent TB?
What is in the vaccine?
- BCG (Bacille Calmette-Guerin)
- Live, attenuated strain of M.bovis
What tests determines whether or not you need a BCG?
- Mantoux/Heaf test
- A lack of inflammatory response from these tests indicates that a BCG is required
What are the 2 phases of TB treatment? How long do they last for?
- Intensive phase (2 months)
- Continuation phase (6-9 months)
What drugs are administered during the intensive phase of TB treatment? (4)
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol (used with or instead of Pyrazinamide)
What drugs are administered during the continuation phase of TB treatment? (2)
- Rifampicin
- Isoniazid
Upper respiratory tract infections include acute inflammatory processes in which parts in the body? (6)
- Nose
- Paranasal sinuses
- Middle ear
- Laryngeal
- Posterior pharynx
- Tonsils
What are the causative microbes of upper respiratory tract infections? (2)
- Bacteria
- Viruses
Explain what happens during pneumonia?
- Inflammation of bronchial and alveolar spaces
- Anoxia
- Altered cardio-pulmonary functions
- Morbidity/Mortality
Give some examples of lower respiratory tract infections (4)
- Pneumonia
- Bronchitis
- Bronchiectasis
- Whooping cough
Give some features of Haemophilus Species (6)
- Gram negative rod
- Facultative anaerobes
- CO2 enhances growth
- Catalase +ve
- Oxidase +ve
- Require X or V factor §
How many antigenic types of Haemophilus influenzae are there? Which one is the important to us?
- 6 types (a-f)
- Type b
Type b Haemophilus influenzae is most associated with what type of disease?
Invasive diseases
Give some features of Corynebacterium diphtheriae (2)
- Gram +ve rods
- Person to person spread via nasopharyngeal secretions
What is the pathogenesis of Corynebacterium diphtheriae?
- C.diptheriae elicit an inflammatory exudate and cause necrosis of faucal mucosa
- C.diphteriae produce a powerful toxin into the bloodstream which causes cell death
What test do we use for distinguishing C.diptheriae?
What do we look for in this test?
- ELEK Test
- Tests for toxin producing microorganisms
What is the treatment for C.diptheriae infections? (3)
- Patient isolation
- Antibiotics
- Early antitoxin therapy
