Download Question Bank –lecture 8-Mycoplasma Q1 Write on the following

Question Bank –lecture 8-Mycoplasma
Q1 Write on the following :
a. General characteristic of mycoplasma
Lack cell walls and are pleomorphic
cannot synthesize peptidoglycan precursors
penicillin resistant
sterols may stabilize plasma membrane
b. most nonmotiles ; some have gliding motility
smallest bacteria capable of self-reproduction
Genomes
less than 1000 genes
one of the smallest found in procaryotes
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b-Metabolism of Mycoplasmas
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b-Metabolism of Mycoplasmas
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Chemo organotrophs
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some produce ATP by glycolysis and lactic acid fermentation.
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some catabolize amino acids and urea
some have functional pentose phosphate pathway.
none have complete TCA cycle
deficient in a number of biosynthetic pathways
c. Important Mycoplasmal pathogens
Mycoplasma mycoides – bovine pleuropneumonia - in cattle
Mycoplasma gallisepticum – chronic respiratory disease in chickens
Mycoplasma hyopneumoniae – pneumonia in swine
Mycoplasma pneumoniae – primary atypical pneumonia in humans
Ureaplasma urealyticum – premature birth, neonatal meningitis and pneumonia
spiroplasmas – pathogenic in insects, ticks, and a variety of plants.
d. Prevalence of Mycoplasma gallisepticum Infection
Mycoplasmas are highly versatile and successful pathogen
Chronic Respiratory Disease: Once infected, infection remains for life
Mycoplasma lack a cell wall: resistant to penicillin group of antibiotics
Antimicoplasmal drugs are bacteriostatic
Antibodies can not eliminate infection
Field infection (MG/MS) level is high due to vertical transmission and low level of biosecurity
Raising mycoplasma clean flocks is not practicable.
e. Major pathogenic Mycoplasmal species in bird
M. gallisepticum
- Chickens, Turkeys
M. synoviae
- Chickens, Turkeys
M. meliagridis - Turkeys
f. Transmission of mycoplasmal infection in bird
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Horizontal
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Within a flock - contact or aerosols
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Between flocks - windborne
Vertical
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Parent to the chick through egg
venereal
h. Target organs for mycoplasma gallisepticum infection:
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Respiratory system
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Synovial membranes ‫سائل الغشاء المفصلي‬
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Reproductive system
g. Vaccines are available; however effectiveness is variable
difficult to culture and biohazard
i. Mycoplasma pneumonia
Primary atypical pneumonia (walking pneumonia)- mild case, does not generally require
hospitalization; spread via droplets
Attaches to receptors in human respiratory tract; interrupt removal of mucus
Common between 5 to 15 yrs. old and adults younger than 40 ; last several weeks
Difficult to diagnose – grow slowly in culture, 2 to 6 weeks
Rx – erythromycin or tetracycline
Prev – personal hygiene, avoid contact with fomites, reduced aerosol dispersion
No vaccine
l. M. pneumoniae Disease
Tracheobronchitis
Atypical interstitial “Walking” pneumonia
All ages affected but more common in younger persons
20-50% of all CAP
Clinically similar to other pneumonias
Extra pulmonary disease
Spread through households
Outbreaks in closed populations
Role in asthma?
Reinfection common – no protective immunity
m. Detection of Genital Mycoplasmas and Ureaplasmas
Culture – good for rapid growing M. hominis and Ureaplasma
Serology – not useful
PCR – needed for M. genitalium
n. Common complicated of Mycoplasmal chronic respiratory disease.
They are Air-saculitis, Pericarditis, perihepatitis.
o. Virulence factors
Not invasive and simply colonize cell surfaces through specific binding
Damage to host tissues may be due to toxic metabolic products
p. Pathogenesis of mycoplasma
Cytadherence
P1 & other proteins
Immunogenic
Cytotoxicity (H2O2) hemolysin  ciliostasis
Induction of inflammation
Cytokine cascade
Antigenic variation
Autoimmunity
Superoxide anions inhibit host catalase increasing oxidative damage