Mycoplasma Flashcards
What is another nickname for Mycoplasma?
pleuropneumonia-like organism = PPLO
(smallest bacteria)
What shape does Mycoplasma take? How is it able to do this?
pleomorphic - lack a cell wall (rather, has a cell membrane)
What are the 3 functions of the electron-dense core terminal organelle/disc present in Mycoplasma?
- adherence/attachment onto host cell surface receptors
- gliding motility
- cell division
What makes Mycoplasma β-lactam, polymixin/colistin, sulfa/trimethoprim, and rifampin resistant?
β-lactam —> no cell wall
polymixin/colistin —> no LPS
sulfa/trimethoprim —> no folic acid synthesis
rifampin —> DNA polymerase is prone to mutation
What 4 cell structures does Mycoplasma lack? 3 toxins? 2 enzymes?
CELL STRUCTURES: cell wall, flagella, fimbriae, LPS
TOXINS: toxins, cytolysins, invasins
ENZYMES: catalase, superoxide dismutase
What makes Mycoplasma have reduced capacities for ATP synthesis?
- does not undergo the TCA cycle
- no quinones
- no cytochromes
What 6 unique structures coat the cellular membrane of Mycoplasma? What are each responsible for?
- glycolipids - antigen mimicry (autoimmunity)
- lipoglycans - antigen mimicry (autoimmunity)
- lipoprotein - switch ON/OFF regularly to change coat
- capsular polysaccharide - block phagocytosis
- host-derived cholesterol - adhesion, invasion
- adhesins - attachment to diverse host epithelial cells
What 7 substances do Mycoplasma secrete?
- hydrogen peroxide - kill host cells by oxidizing their lipids, proteins, DNA, and RNA
- superoxide - kill host cells by oxidizing their lipids, proteins, DNA, and RNA
- nucleases - degrade host nucleic acids
- immunoglobin protease - degrade antibodies
- antioxidant enzymes - detoxify free radicals
- sialidase - degrade mucus to reach epithelium
- hyaluronidase - degrade hyaluronate
How do Mycoplasma grow on media? What 7 substances are required in media for its growth?
- highly fastidious and slow grower (1-2 weeks, chronic disease)
MYCOPLASMA AGAR
1. beef heart infusion
2. peptone
3. 5% yeast autolysate
4. nucleic acid precursors
5. penicillin - block Gram-positive bacterial growth
6. thallium acetate - block Gram-negative bacterial growth
7. 20% equine/human serum - provides cholesterol, amino acids, and fatty acids for cell membrane synthesis
What morphology does Mycoplasma undertake on media? How does it compare in different species?
fried egg colony with unique gliding motility
CATTLE —> M. mycoides subsp. mycoides —> small colony
GOAT —> M. mycoides subsp. mycoides —> large colony
What 8 antioxidant enzymes are produced by Mycoplasma? What is their function?
- methionine sulfoxide reductase
- organic hydroperoxide reductase
- osmotically inducible protein C
- superoxide dismutase
- catalase
- thioredoxin reductase
- thiol reductase
- peroxiredoxin
ensures bacterial survival in the presence of free radicals
What virulence factors are responsible for antigenic variability? Antigen mimicry?
- lipoprotein
- glycolipids
- lipoglycans
(autoimmunity, escapes detection by the immune system)
What does it mean when Mycoplasma “caps?”
incorporated host antigens into itself, allowing escape from the immune system
How is Mycoplasma able to survive in host cells? What can this lead to?
manipulate host genome
disease —> cancer?
How does Mycoplasma cause disease?
- infection elicits inflammation (IL-1, 2,6) which can lead to MAKePSR syndrome, autoimmunity, and immune invasion
- further immune evasion results in chronic inflammation
- chronic inflammation can inhibit p53, a tumor suppresor protein, in host cells
What are the 2 lifestyles of Mycoplasma?
- INTRACELLULAR: alters host cell morphology and genetic architect to cause chronic diseases including colon, gastric, lung, prostate, and renal cancers
- EXTRACELLULAR: resides outside host cells very intimately to membrane surface
What are the 5 transmission routes of Mycoplasma?
- airborne** (as far as 9.2 km, like Chlamydia and Coxiella)
- contact
- sexual intercourse (humans)
- ingestion
- vertically by transovarial (birds)
What is a common way of contact being a transmission route of Mycoplasma? What does this cause?
sharing the same milking machines in dairy farms
Mycoplasma mastitis
What are 2 major sources of Mycoplasma infection?
- introduction of an infected animal into an uninfected population
- dispersed by wind/air
What is the host range of Mycoplasma? What body systems are most commonly affected?
all vertebrates and fleas
mucosal tracts —> MAKePSR
(respiratory tract, urogenital tract, conjunctiva, alimentary canal, mammary glands, joints)
What reproductive diseases does Mycoplasma cause?
- abortion
- vulvovaginitis
- infertility
- endometritis
- dystocia
What are the 3 major species of Mycoplasma causing disease in cattle?
- M. mycoides subsp. mycoides small colony variant
- M. bovis
- M. agalactia
What does Mycoplasma bovis and Mycoplasma mycoides subsp. mycoides small colony variant cause in cows? What are 5 major symptoms on a physical exam that point towards this?
contagious bovine pleuropnemonia (CBPP) - trade ban by OIE
- extended head/neck forward
- open mouth
- legs far apart with elbows pointed out
- coughing
- ocular and nasal discharge
What are 3 pathologies caused by contagious bovine pleuropneumonia (CBPP) seem postmortem?
- collection of pleural fluid in thorax
- thickening of the interlobular septa of lung, giving it a marbled appearance (meaty, fibrin)
- lung adherence to chest wall (lungs unable to collapse and refill —> hypoxia)
What are 6 common diseases caused by Mycoplasma bovis?
- mastitis
- pneumonia (calf)
- polyarthritis (calf)
- metritis
- abortion
- sterility
What species of Mycoplasma cause contagious caprine pleuropneumonia (CCPP)?
M. capricolum subsp. capripneumoniae
- trade ban!
What are the 4 major species of Mycoplasma causing disease in sheep/goats?
- M. capricolum subsp. capricolum - mastitis, arthritis
- M. mycoides subsp. capri - pneumonia, mastitia, arthritis, septicemia
- M. agalactiae - infectious agalactia
- M. ovipneumoniae - pneumonia (lambs)
What is the most common clinical sign of Mycoplasma agalactiae in sheep/goats?
mammary gland atrophy
- conjunctivitis
- arthritis
What are 2 postmortem findings in M. capricolum, M. mycoides, and M. ovipneumoniae infection? 5 clinical symptoms?
- granular lung appearance
- marbled and hepatization of lung
high fever, anorexia, productive cough, wide stance, extended neck
What is the most common Mycoplasma species causing infection in swine? What does it cause? 2 postmortem findings?
M. hyopneumoniae —> enzootic pneumonia
- lung hepatization - lung discoloration and consolidation
- lung lobe collapse (deflated)
What are the 3 most common Mycoplasma species causing disease in poultry? What do they cause?
- M. gallicepticum - chronic respiratory disease (CRD) in chicken, sinusitis and infectious air sacculitis in turkey
- M. synoviae - air sacculitis, arthritis, tendosynovitis
- M. meleagridis - air sacculitis, sinusitis, arthritis (turkey)
- trade ban in USA
How are the air sacs affected by Mycoplasma gallisepticum and M. synoviae infection?
thickened and cloudy
(+ thickened blood vessels)
What are common clinical signs of Mycoplasma gallisepticum infection in turkeys? Chickens?
sinusitis with swollen infraorbital sinuses and a clear mucoid exudate + dried nasal exudate
conjunctivitis, periorbital swelling, and dried nasal exudate
What are 2 common clinical signs in chickens affected by Mycoplasma synoviae?
- swollen footpad with granulation tissue and purulent discharge surrounding digital flexors
- swollen hock joint with viscous yellow exudate around the tendons
What Mycoplasma species affects horses? What does it couse?
M. felis - pleuritis
What 2 species of Mycoplasma affect pets? What do they cause?
- M. cynos - pneumonia
- M. felis - conjunctivitis, penumonia (cats)
What 2 species of Mycoplasma cause severe hemolytic anemia in dogs and cats? How are they transmitted?
- M. haemocanis
- M. haemofelis
- FLEAS
(used to be part of Haemobatonella)
What 3 Mycoplasma species affect humans? What do they cause?
- M. pneumoniae - pneumonia, tracheobronchitis
- M. hominis - urogenital disease, vaginosis (STD); 21-53% of women carry asymptomatically
- M. genitalium - reproductive diseases of males and females (STD)
What 3 species of Mycoplasma are causes of trade bans in poultry by the USDA? 2 that cause a trade ban in goats and cattle by the OIE?
M. gallisepticum, M. synoviae, M. meleagridis
M. capricolum subsp. capripneumoniae (CCPP)
M. mycoides subsp. mycoides (CBPP)
What are the 6 major pathologies of the lung due to Mycoplasma infection?
- thickening
- extensive fibrin and fibrosis
- hepatization
- marbline
- granuloma with poor blood perfusion
- encapsulation (+/- necrosis)
What pathologies are found in the thoracic cavity and joints due to Mycoplasma infection?
straw-colored fluid acumulation
swollen + exudate
What 3 aspects of the iceberg concept relate to Mycoplasma infection?
- can be carried asymptomatically, but herds/flocks have a high rate of morbidity due to close confinement
- proportion of dead animals among infected (mortalities) ranges from 30-80%
- 25% of recovered animals become carriers
What is the gold standard of isolating Mycoplasma? What is a major limitation? What else is commonly done?
culturing on agar with the typical fried egg appearance with gliding motility - detects only 30-50% using bulk milk or individual cow of subclinical infections (low sensitivity)
- serology (surveillance and biosecurity): direct/indirect fluorescent staining, ELISA, slide agglutination test
- PCR: nucleic acid based test (best considering limitations of culture)
What are the 3 antimicrobials of choice for Mycoplasma infections? What are 3 common causes of poor responsiveness to treatment?
- Doxycycline
- Tetracycline
- Erythromycin
bacteria….
- is slow growing
- can sequester in granulomas
- can hide intracellularly
(culling implications of infected animals!)
In what 4 ways is Mycoplasma infection commonly controlled/prevented?
- chemotherapy of infected herd/flock
- vaccination - live and killed vaccine decreased clinical signs and pathologies, can still be infected and be carriers
- biosecurity - ALL-IN-ALL-OUT PRACTICE, single age farms, segregation, traffic control, cleaning and disinfection
- test and cull positive animals
What is the overall recommended way of controlling Mycoplasma disease? Why?
culling
neither antibiotics nor vaccines are effective for treatment
