Filamentous and/or acid-fast rods Flashcards
What distinguishes acid-fast bacteria from gram-staining ones?
Length of mycolic acid on cell’s cell wall (exterior to peptidoglycan)
How could you identify a culture of Actinomyces?
gram stain
oxygen needs?
Colony shape?
contents of lesion?
natural colony location?
When do infections occur?
- gram positive (branching filamentous appearance); non acid fast rod
- anaerobic
- Molar tooth appearance
- sulfur granules (bright yellow) in clinical sample
- colonize mouth, colon and vagina
- no person-person spread
- infection when mucosal barrier disrupted
What disease is characterized by the following symptoms
chronic pyogenic infection, common in individuals with poor hygeine; 3 times more common in men than women
indurated masses with fibrous walls & central loculations
multiple abscesses with sulfur granules
What bacteris is responsible for this disease?
Actinomycosis
Actinomyces israelii
can present as cervicofacial, abdominal/pelvic, or thoracic
How could you identify a culture of Nocardia?
gram stain?
oxygen requirements?
culture on BYCE agar?
Natural colony location?
- gram positive filamentour rod; weak acid fast
- aerobic
- aerial hyphae
- worldwide saprophyte (normal soil microflora)
- infections from inhalation, not person-to-person
How does Nocardia produce pathology?
produces catalase & SOD- neutralize ROS
prevent acidification of phagosome & rusion with lysosome
PMN can phagocytose, but can’t kill – CMI needed for cure.
What disease is characterized by the following symptoms?
sub-acute presentation, cough, dyspnea, fever
cavitation & dissemination to CNS or S/C tissues (painless, localized S/C swelling, suppuration)
What is the likely bacterial cause?
Bronchopulmonary nocardiosis
Cutaneous nocardiosis
Nocardiosis
What disease is characterized byt the following symptoms?
How could you identify a culture of Mycobacterium tuberculosis?
oxygen need?
gram stain?
growth speed?
latency?
Lowenstein-Jensen agar?
Middlebrok 7H10/7H11 agar?
Where are infections most common?
- obligate aerobic
- acid-fast bacilli w/ complex lipid coat
- early-morning suptum after mild alkali treatment
- 3 consecutive days
- grows very slow (doubles every 24 hrs)
- can survive in latency for decades inside the human host
- arabinogalactan important for host interaction & survival in macrophage
- Lowenstein-Jensen agar = growth
- Middlebrook 7H10/7H11 = cauliflower morphology
- sub-Saharan Africa, Asia, Eastern Europe
How is M. tuberculosis spread?
What is risk of disease dependent on?
How can the body keep the infection latent?
What is the difference between primary and secondayr tuberculosis?
small nuclei aerosolized from coughing can remain suspended for hours
infection occurs when they are breathed in to reach the terminal air passages
risk of disease depends on infection dose and immune system
prevents phagosome to fuse with the lysosome– CMI keep bacilli dorman in walled off locations (granuloma)
Symptoms w/in first year after infection = primary tuberculosis (~5%)
What disease is characterized by the following symptoms:
Patchy conosolidation, nodules and cavities in regions with high oxygen content
fever, cough, night sweats, weight loss
Tuberculosis
How can you test M. tuberculosis exposure?
For what groups is 5mm positive? 10mm? 15 mm?
Why is this not always effective? What is the alternative?
Mantoux test
Inject antigens that are extraced from mycobacteria cell wall (purified protein derivitives) into dermal layer
48-72 hrs, person will react = erythmation
- 5mm = positive
- HIV-positive
- Recent contacts
- immunosuppressed patients
- 10 mm = positive
- recent immigrants
- injection drug users
- prision & healthcare workers
- MTB lab personnel
- 15 mm = positive
- persons w/ no know risk factors
People who have been vaccinated will test positive on every PPD skin test –> TB Gold Test
Take blood; incubate that blood with antigens specific to MTB (ESAT-6 and CFP-10); if positive will produce measurable amounts of IFN-gamma; indicates further testing NOT that the person has tuberculosis
How could you identify a colony of Mycobacterium leprae?
growth speed?
Gram stain?
temperature sensitive?
Route of transmission?
- slow grower (replicated everye 7 minutes)
- Acid-fast intracelular parasite
- poor growth above 30 degrees C (only impact dermis)
- transmitted through skin/mucus lining of nose/throat
What disease is characterized by the follwing symptoms:
Slow progressioninvolving superficial tisues; few flat or slightly raised skin lesions; pale or slightly red, dry and numb to touch
Tuberculoid Leprosy
Mycobacterium leprae
What disease is characterized by the follwing symptoms:
Complete loss of sensations; thickening of peripheral nerves
What is probably true about this patient?
Lepromatous Leprosy
M. leprae
Reduced or absent CMI
What bacteria cause the following symptoms:
granulomas from swimming pool (fish tank); reddish or tan skin bump
M. marinum; M. ulcerans
