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MYCOPLASMA 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: 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 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 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 + - + Prostatitis + - + Urinary calculi + - - Pyelonephritis + + - Bacterial vaginosis + + - Cervicitis - - + Pelvic inflam. disese - + + Infertility + - - Chorioamnionitis + + - Spont. Abortion + + - Low birth weight + - - Postpartum fever + + - Neonatal pneumonia/meningitis + + - Extragenital disease adults (arthritis) + + + 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