Lecture 6 - Flashcards
Mycobacteria
- Causative agents of tuberculosis and leprosy
Waxy coat (NO Gram stain, Resistant to disinfectants) - Acid-fast bacilli –> Resist decolorization
- Use Ziehl-Neelsen staining technique
Mycobacteria: Ziehl-Neelsen staining
- Used for staining Mycobacteria
- You boil the sample on the slide for ten minutes, do remove the wax cell wall
Mycobacterium tuberculosis
- Chronic slow-progressing pulmonary infection; transmission by aerosol droplets
- Obligate aerobe, facultative intracellular parasite
- 4-6 WEEKS to see colonies on a plate
- —> Use microscopyof sputum smears as firstline of diagnosis
- Leading cause of death world-wide form a single infection
- Infection develops in stages
Stages of Mycobacterium tuberculosis
- Primary tuberculosis
- Post-Primary tuberculosis
- Immunity tuberculosis
Primary tuberculosis
- Aerosol inhalation
- Bacteria multiplication in alveoli
- macrophage ingestion of bacilli and formation of 1st complex
- Foci of infection in lungs (may spread to kidneys, bones, meninges)
- CMI is fully active, infection is stopped (majority of cases)
- Some bacilli survive, reactivation several years later
Post-Primary tuberculosis
- Late reactivation of lesions in lungs, kidneys, bones etc
- 5% of cases; higher in patients with AIDS
- Chronic infection
Immunity tuberculosis
- Cell mediated immunity is most important (T-cells)•
- Mantoux test
- Tuberculin solution is injected INTRADERMALLY, wait 48-72 hrs, check for induration
- Record diameter of induration
- > 10mm POSITIVE
- 5-9 mm Doubtful, maybe cross reaction with other Mycobacteria
- <4mm NEGATIVE
- A positive test does not necessarily mean there is currently an active infection
Mycobacterium tuberculosis:
Laboratory Diagnosis
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Non Tuberculous Mycobacteria
- Tuberculoid leprosy
- Leopromatous leprosy
Non Tuberculous Mycobacteria:
Epidemiology
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Non Tuberculous Mycobacteria:
Diagnosis
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Non Tuberculous Mycobacteria:
Treatment
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Spirochetes
1- Treponema Pallidum
2- Lyme Disease
3- Leptospira Interrogans
Treponema Pallidum
- Syphylis
- Gram Negative, helical bacteria
Spirochetes: Syphilis Stages
Treponema Pallidum
- Primary syphilis
- Secondary syphilis
- Latent syphilis
- Late syphilis
Primary syphilis
- Appearance of chancre 3-4 weeks after infection
- Fluid from lesion contains bacteria (seen under dark field microscopy
Secondary syphilis
c
Latent syphilis
.
Late syphilis
.
Spirochetes: Syphilis
Serology
- Non treponemal test
- Treponemal test
Spirochetes: Syphilis
Serology: Non treponemal test
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Spirochetes: Syphilis
Serology: Treponemal test
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Syphilis: Mircoscopy
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Syphilis: Culture
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