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MYCOBACTERIA CORYNEBACTERIA LEGIONELLA

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LEGIONELLA. Faculty: Dr. Alvin Fox. KEYWORDS. Acid Fast. Tuberculosis ... This child has diphtheria resulting in a thick gray. coating over back of throat. ... – PowerPoint PPT presentation

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Title: MYCOBACTERIA CORYNEBACTERIA LEGIONELLA


1
MYCOBACTERIACORYNEBACTERIALEGIONELLA
Faculty Dr. Alvin Fox
2
KEYWORDS
  • Acid Fast
  • Tuberculosis
  • M. tuberculosis
  • M. avium - M. intracellulare complex
  • M. bovis
  • M. leprae
  • Atypicals
  • Tubercle
  • PPD
  • Tuberculin
  • Mycobactin
  • Cord factor
  • BCG
  • Leprosy (Hansen's Disease)
  • Runyon groups
  • Mycolic acids
  • Diphtheria
  • C. diphtheriae
  • Loeffler's agar
  • Tellurite agar
  • Metachromatic bodies
  • Diphtheria toxin
  • Schick test
  • Diphtheroids
  • Legionella pneumophila
  • Legionnaires disease
  • Pontiac fever
  • Legionella micdadei
  • Pittsburg pneumonia

3
Mycobacteria
  • obligate aerobe
  • acid-fast rods

4
Mycobacterium tuberculosis
5
Tuberculosis (TB, consumption)
  • M. tuberculosis
  • major human disease
  • healthy people
  • problems
  • association with AIDS
  • multiple drug-resistance

6
  • M. avium- M. intracellulare complex (M. avium)
  • non-AIDS
  • infection almost never
  • AIDS
  • major bacterial opportunist
  • multiple drug-resistance

7
M. bovis
  • spread from cattle
  • infected cattle are culled
  • positive skin test
  • rarely seen in US

8
M. leprae
  • leprosy
  • major disease of third world
  • rare in US

9
Other mycobacteria
  • Atypicals

10
Transmission -tuberculosis
  • M. tuberculosis causes disease
  • healthy individuals
  • transmitted man-man
  • airborne droplets

11
Mycobacterium tuberculosisin lung
12
Pathogenesis of tuberculosis
  • infects lung
  • distributed within macrophages
  • facultative intracellular pathogen
  • inhibits phagosome-lysosome fusion
  • resists lysosomal enzymes

13
Cell-mediated immunity -tuberculosis
  • infiltration
  • macrophages
  • lymphocytes
  • granulomas
  • tubercules

14
Laboratory diagnosis - tuberculosis
  • skin testing
  • delayed hypersensitivity
  • tuberculin
  • protein purified derivative, PPD
  • X-ray

15
Positive skin test -tuberculosis
  • indicates exposure to organism
  • does not indicate active disease

16
  • Other minor pathogenesis factors
  • tuberculosis
  • mycobactin
  • siderophore
  • cord factor
  • damages mitochondria

17
Laboratory diagnosis M. tuberculosis
  • acid fast bacteria
  • sputum

18
Laboratory diagnosis M. tuberculosis (culture)
  • grows very slowly
  • several weeks
  • non-pigmented colonies
  • niacin production
  • differentiates from other mycobacteria

19
Tuberculosis
  • polymerase chain amplification
  • rapid diagnosis

20
Antibotic treatment - tuberculosis
  • extensive time periods (e.g. 9 months)
  • organism grows slowly, or dormant
  • two or more antibiotics
  • e.g. rifampin and isoniazid
  • resistance minimized

21
Vaccination
  • BCG vaccine
  • an attenuated strain of M. bovis
  • not effective
  • in US,
  • incidence is low
  • vaccination not practiced
  • immunization interferes with diagnosis

22
Mycobacterium leprae
23
Leprosy (Hansen's Disease)
  • M. leprae
  • causative agent
  • chronic disease
  • disfigurement
  • rarely seen in the U.S.
  • common in third world
  • millions of cases
  • infects the skin
  • low temperature

24
  • ulcers, resorption of bone
  • worsened from careless use of hands (nerve damage)

25
Leprosy
  • tuberculoid
  • few organisms
  • active cell-mediated immunity
  • lepromatous
  • immunosuppression
  • few organisms

26
Production of M. leprae antigens and
pathogenesis studies
  • in vitro
  • unculturable
  • in vivo growth
  • low temperature
  • armadillo
  • mouse footpad

27
Leprosy
  • lepromin
  • skin testing
  • acid-fast stains
  • skin biopsies
  • clinical picture

28
Atypicals - mycobacteria (including M. avium)
other than M. tuberculosis and M. leprae
  • infect compromised host
  • not transmitted man -man
  • healthy people

29
Atypical mycobacterial diseases
  • tuberculosis-like
  • leprosy-like

30
Mycobacterium avium and AIDS
31
  • Mycobacteria and AIDS
  • M. avium is much less virulent than M.
    tuberculosis
  • does not infect healthy people
  • infects AIDS patients
  • M. avium infects
  • when CD4 count greatly decreased
  • M. tuberculosis infection
  • infects healthy people
  • infects AIDS patients
  • earlier stage of disease
  • more systemic

32
Clinical features with AIDS
  • systemic disease (versus pulmonary)
  • greater in AIDS
  • lesions often lepromatous


33
Antibiotic therapy
  • selected primarily for M. tuberculosis
  • if M. avium suspected other antibiotics included

34
Other atypicals
  • pigmented or not
  • pigmentation
  • light
  • dark
  • growth
  • fast
  • slow

35
Mycobacterial species identification
  • cellular fatty acid profiles
  • mycolic acid profiles
  • genetic markers

36
Mycolic acids
  • mycobacteria
  • longest chain length
  • strongly acid fast
  • nocardia
  • intermediate chain length
  • weakly acid fast
  • corynebacteria
  • shortest chain length
  • not acid fast

37
Corynebacterium diphtheriae
38
Corynebacterium diphtheriae
  • Gram positive
  • strict aerobe
  • pleomorphic

39
Diphtheria
  • infection
  • upper respiratory tract (pharynx)
  • pseudomembrane
  • chocking
  • bacteria do not spread systemically
  • .

40
This child has diphtheria resulting in a thick
gray coating over back of throat. This coating
can eventually expand down through airway and,
if not treated, the child could die from
suffocation CDC
41
Diptheria toxin
  • spreads
  • systemic and fatal injury

42
Diphtheria toxin
  • B binds to host cell
  • A inhibits protein synthesis
  • ADP-ribose moiety (NADH) attaches
  • rare amino acid, diphthamide
  • elongation factor 2 inhibited

43
Treatment
  • anti-toxin
  • antibiotic

44
Immunization against diphtheria (infant)
  • disease vanished in US
  • without immunization will return
  • toxoid ( pertussis and tetanus) DPT
  • neutralizing antibodies
  • colonization not inhibited
  • found in normal flora

45
Testing immunity
  • Schick skin test

46
Diphtheria toxin
  • coded by bacteriophage tox gene
  • not synthesized if iron present
  • iron-repressor complex forms
  • inhibits expression of tox gene

47
Identification - C. diphtheriae
  • growth Loeffler's medium
  • stain for polyphosphate granules
  • metachromatic
  • polyphosphate granules (pink) cell (blue)
  • tellurite agar
  • reduction by bacteria
  • tellurium precipitation
  • black colonies

48
Exotoxin production
  • in vivo
  • in vitro

49
  • C. diphtheriae should not be confused with
  • diphtheroids
  • other corynebacteria
  • propionibacteria

50
Legionella pneumophila
51
Legionella pneumophila
  • Legionnaire's disease.
  • pneumonia
  • fatal if not treated
  • erythromycin
  • Pontiac fever
  • flu-like
  • milder
  • self-limiting
  • myalgia (muscle pain)
  • no pneumonia

52
Transmission
  • contaminated air
  • infected water supply
  • not spread person-person

53
Legionnaires disease
  • small epidemics
  • healthy people
  • more frequently
  • sick or elderly
  • hospitals
  • immunocompromised

54
Identifcation of Legionella
  • no growth conventional agar
  • e.g. sheep blood agar
  • media must contain
  • iron
  • cysteine
  • e.g. charcoal yeast extract agar
  • isolation clinical specimens
  • poor

55
Legionella pneumophila
  • stains poorly
  • Gram negative rod

56
Legionella pneumophia
  • environmental reservoir
  • pools of stagnant water
  • hot water towers
  • air conditioning systems
  • intracellular growth, protozoa
  • facultative intracellular pathogen
  • humans

57
Legionnaires disease -indoor air quality
  • contaminated buildings
  • air conditioning system
  • water supply

58
Legionellae
  • Legionella pneumophila
  • several serogroups
  • most infections, serogroup 1
  • Legionella micdadei
  • Pittsburg pneumonia
  • Other Legionella
  • occasional disease
  • legionellosis

59
Identification of Legionella
  • fatty acid profiling
  • DNA-DNA hybridization
  • 16S rRNA sequence
  • Detection of antigen in urine
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