Download M. pneumoniae

MYCOPLASMA
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Smallest, free-living (0.1 to 0.8 um)
lack cell wall
Require growth factors
Except M. pneumoniae, all are facultative anaerobes, with fried-egg shaped
colonies seen on agar
 M. genitalium and Ureaplasma urealyticum – cause nongonococcal urethritis
 M. hominis – cause pyelonephritis, postpartum fever, PID
Class Mollicutes (The Mycoplasmas) :
• Lack cell walls and are pleomorphic
• cannot synthesize peptidoglycan precursors
• penicillin resistant
• sterols may stabilize plasma membrane
• most nonmetals; some have gliding motility
• smallest bacteria capable of self-reproduction
• Genomes
less than 1000 genes
one of the smallest found in procaryotes
Metabolism of Mycoplasmas:
• Chemo organotrophs
• some produce ATP by glycolysis and lactic acid fermentation.
• some catabolize amino acids and urea
• some have functional pentose phosphate pathway.
• none have complete TCA cycle
deficient in a number of biosynthetic pathways
Important pathogens:
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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
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 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
Major pathogenic species:
M. gallisepticum - Chickens, Turkeys
M. synoviae
- Chickens, Turkeys
M. meliagridis
- Turkeys
M. iowae
- Turkeys
Smallest self replicating prokaryotes
Lack of cell wall, bounded by cell membrane
Fragile – easily killed out side its host by disinfectants
Economic significance
• Costliest Disease in Poultry
• Mortality
• Reduced feed conversion
• Loss of weight
• Complications with – IB, ND, E coli
• Condemnations
• Drop in egg production
• Reduced hatchability & chick viability
• Cost of eradication and control programs
Transmission
• Horizontal
– Within a flock - contact or aerosols
– Between flocks - windborne
• Vertical
– Parent to the chick through egg
venereal
Target organs:
– Respiratory system
– Synovial membranes
– Reproductive system
Incubation period:
– Chronic slow spreading
– Varies from 6-21 days
Clinical Signs
– Coughing, sneezing, Nasal discharge
– Foamy secretions in the eye
– Open mouthed breathing
– Tracheal rales
– Reduced feed consumption
– Loss of weight – more stunted chicks
– Drop in egg production – layer, breeder
– Reduced hatchability, chick viability
– Lameness
– Morbidity – up to 100%
– Mortality – up to 30% in young, negligible in adults.
Gross Lesions:
• Sinusitis and conjunctivitis
• Tracheitis with excessive mucus
• Airsacculitis
• Pneumonia
• Synovitis
• Osteomyelitis
• Salpingitis
Complicated Chronic Respiratory Disease Air-saculitis, Pericarditis,
perihepatitis
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A bacteria that causes both arthritis and pneumonia in growing-finishing pigs
Mycoplasma hyorhinis and Mycoplasma hyosynoviae cause arthritis
Mycoplasma hyopneumoniae causes pneumonia
Most swine herds are infected with mycoplasma
Vaccines are available; however effectiveness is variable
Lincomycin seems to be an effective treatment
SPF stock are mycoplasma free
Classification – order Mycoplasmatales; family Mycoplasmataceae; 2 medically
important genera
 Mycoplasma
 Ureoplasma
 Three common clinical isolates – M. pneumoniae, M. hominis, and U.
urealyticum
 Morphology and cultural characteristics
 Do not possess the distinctive cell wall of bacteria
 Plasma membrane is the outermost part of the organism and is unique in
bacteria in that it has a high content of sterols that act to prevent osmotic lysis
 Very small in size (too small to be seen with an ordinary light microscope)
and highly pleomorphic
 Don’t stain with a Gram’s stain
 Non-motile
 May possess a capsule
 Although some are free living, most are closely adapted parasites
 Grow on media enriched with serum (need cholesterol)
 Grow beat at 35-370 C either aerobically or anaerobically
 M. pneumoniae grows in 5-14 days, M. hominis in 2-4 days, and U.
urealyticum in 24-28 hours.
 M. pneumoniae colonies resemble fried eggs and can be stained with Dienes
stain (they stain blue)
Identification:
M. pneumoniae
 Isolation in culture
 Ability of colonies to hemolyze guinea pig RBCs
 Rise in specific antibody titer
 Cold agglutinin test – a nonspecific test in which the patient produces cold
reacting antibodies that agglutinate type O human RBCs at 40 C, but not at
370 C
 A single titer of 1:128 is significant and occurs in 7 days and disappears in 6
weeks.
 M. hominis
 Isolation in culture
 No hemolysis of guinea pig RBCs
 U. urealyticum
 Urease production
Virulence factors
 Not invasive and simply colonize cell surfaces through specific binding
 Damage to host tissues may be due to toxic metabolic products
 Clinical significance
 M. pneumonia – the major cause of primary, atypical pneumonia (walking
pneumonia)
 Transmitted by droplet infection
 After a 2-3 week incubation, the disease begins as a mild, upper respiratory
tract infection and progresses to fever, headache, malaise, and a dry cough
which is usually mild and self-limited.
 3-10% develop clinically apparent pneumonia with occasional complications
of arthritis,rashes, cardiovascular problems, or neurological problems.
 Genital tract infections - caused by M. hominis and U. ureolyticum which may
also be found as part of the NF in the genital tract
 May cause nongonococcal urethritis, PID, post-partum fever, infertility,
stillbirth, spontaneous abortion, and acute urethral syndrome
Treatment
 M. pneumonia – tetracycline or erythromycin
 Genital infections - tetracycline
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
Pathogenesis
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
MP CARDS toxin - ADP ribosyl transferase induces vacuolation & ciliostasis of
epithelium
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
Diseases due to Genital Mycoplasmas
Commensals in lower urogenital tract in normal sexually active adults
Condition
Ureaplasma
M. hominis
M. genitalium
Male urethritis
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Prostatitis
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Urinary calculi
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Pyelonephritis
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Bacterial vaginosis
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Cervicitis
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Pelvic inflam. disese
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Infertility
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Chorioamnionitis
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Spont. Abortion
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Low birth weight
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Postpartum fever
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Neonatal
pneumonia/meningitis
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Extragenital disease adults
(arthritis)
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Detection of Genital Mycoplasmas and Ureaplasmas:
Culture – good for rapid growing M. hominis and Ureaplasma
Serology – not useful
PCR – needed for M. genitalium
Swine Mycoplasma
A bacteria that causes both arthritis and pneumonia in growing-finishing pigs
Mycoplasma hyorhinis and Mycoplasma hyosynoviae cause arthritis
Mycoplasma hyopneumoniae causes pneumonia
Most swine herds are infected with mycoplasma
Bloody scours continued
There is no effective vaccine available
Treatment includes the use of antibiotics
Carbadox (Mecadox) and Lincomycin are two drugs of choice