Chapter 38: Mycoplasma Flashcards by Kyle Mendoza

Describe mycoplasma

Smallest free-living prokaryotic microorganism

How well did you know this?

Not at all

Perfectly

Membranes of mycoplasma

Possess triple-layered limiting membranes but lack cell walls

How well did you know this?

Not at all

Perfectly

Gram method staining

It does not stain in Gram method staining

How well did you know this?

Not at all

Perfectly

Shape

Highly pleomorphic, filterable, plastic forms

How well did you know this?

Not at all

Perfectly

Environment susceptibility

-susceptible to dessication and disinfectants

How well did you know this?

Not at all

Perfectly

Microcolonies

-fried egg appearance

How well did you know this?

Not at all

Perfectly

Host

Most are host-specific

How well did you know this?

Not at all

Perfectly

Replication

Do not replicate in the environment

How well did you know this?

Not at all

Perfectly

Environment

-most are facultative anaerobes

How well did you know this?

Not at all

Perfectly

Contain species of vet importance

-Mycoplasma
-Ureaplasma

How well did you know this?

Not at all

Perfectly

Cause a wide range of diseases in animals, including contagious bovine pleuropneumonia

-Mycoplasma species

How well did you know this?

Not at all

Perfectly

Microorganisms in the class

Mollicutes

How well did you know this?

Not at all

Perfectly

Smallest prokaryotic cells capable of self replication

Mycoplasma

How well did you know this?

Not at all

Perfectly

Shape

Pleomorphic ranging from sperical to filamentous

How well did you know this?

Not at all

Perfectly

Size:
-spherical
-filamentous

-0.3 to 0.9 um in diameter
-up to 1.0 um long

How well did you know this?

Not at all

Perfectly

Cannot synthesize

Peptidoglycan or it’s precursor

How well did you know this?

Not at all

Perfectly

Cannot synthesize peptidoglycan or its precursor thus

-they do not possess rigid cell walls but have flexible, triple-layered outer membranes
-their flexibility allows them to pass through bacterial membrane of pore

How well did you know this?

Not at all

Perfectly

their flexibility allows them to pass through bacterial membrane of pore sizes from

0.22 um to 0.45 um

How well did you know this?

Not at all

Perfectly

Are susceptible to:

-dessication
-heat
-detergents
-disinfectants

How well did you know this?

Not at all

Perfectly

Resistant to antibiotics:

-penicillin

How well did you know this?

Not at all

Perfectly

Interfere with the synthesis of bacterial cell walls

Penicillin

How well did you know this?

Not at all

Perfectly

Phylogenetically mycoplasmas are linked to Gram-positive such as _____ based on 5S RNA sequences analyses

Clostridium

How well did you know this?

Not at all

Perfectly

Have a low guanine cytosine content in their DNA

How well did you know this?

Not at all

Perfectly

Requirement

Enriched media for growth

How well did you know this?

Not at all

Perfectly

Colonies when illuminated obliquely

Umbonate microcolonies

Microcolonies appearance in transmitted light

'Fried egg'

Due to extension of microcolony into agar

Dense central zone

-First mycoplasma identified in 1890 -Cause contagious bovine pleuropneumonia

-*Mycoplasma mycoides* subsp. *mycoides*

Similar types of mycoplasmas subsequently identified were called

-Pleuropneumonia-like organisms (PPLO)

Grow optimally in an atmosphere og

5 to 20% CO2

Non-pathogenic anaerobic mycoplasmas found in

Rumens of sheep and cattle

Associated with reproductive disorders

-*Mycoplasma* and *Ureaplasma*

Known as ______ or ______ (trivial name) as they parasitize rbc

-Haemotropic mycoplasmas -haemoplasmas

Found in:

-conjunctiva -nasal cavity -oropharynx -intestinal and genital tracts of humans and animals

-found in rbc -host specific (some) -cross the species barrier more often -signifucant in immunocompromised or stressed animals

-Haemotropic mycoplasma

Survival in environment

Short periods

Differentiated by their

-host specificity -colonial morphology -requirement for cholesterol -biochemical reactivity

*Mycoplasma* spp. and *Ureaplasma* spp. Requirement for enriched media:

-animal protein -sterol component -source of DNA or adenine dinucleotide

Commercially available mycoplasma agar or broth media (often heart infusions):

-supplemented with 20% horse serum -yeast extract providing amino acids and vitamins

Used to inhibit Gram-positive bacteria

Penicillin

Incorporated to inhibit Gram-negative bacteria and fungi

-Thallous acetate

Media buffered at:

-*Mycoplasma*- pH 7.3 to 7.8 -*Ureaplasma* -pH 6.0 to 6.5

Culturing of ureoplasmas

Urea is added to the medium and thallous acetate, which is toxic for these organisms, is omitted (?)

Occasionally grow as contaminants on mycoplasma media

*Acholeplasma* spp

Size of unstained microcolonies of *Mycoplasma* species are

-0.1 to 0.6 mm in diameter -have a fried egg appearance -some 1.5 mm and can be seen w/o magnification

*Ureaplasma* -size -lacks -referred -stain

-0.02 to 0.06 mm -lack peripheral zone -T-mycoplasma (bc tiny colonies) -Dienies stain -central zone- dark blue - peripheral zone- lighter blue

*Mycoplasma* requires differentiation from colonies of...

Bacterial L-forms

-lack rigid cell walls -assume shapes resembling mycoplasmas -can revert to their normal bacterial shape...

-Require sterols for growth -reflected in their sensitivity to inhibition by digitonin

*Mycoplasma* and *Ureaplasma*

-Sterol-independent -resistant to inhibition by digitonin

-*Acholeplasma* species

Digitonin sensitivity test

Exceeding 5 mm means it is sensitive to digitonin

Do not metabolize urea

*Mycoplasma*

Produces urease

-*Ureaplasma*

Growth inhibition tests

-8 mm zone of growth inhibition develops, containing homologous antiserum

T1 vaccine strains for contagious bovine pleuropneumonia

Do not produce specific toxins or invasins

Important in its ability to produce disease

-Intrinsic metabolic functions

Essential attribute for pathogenicity but mycoplasma do not invade the cells

Ability to adhere to host cells

Evade immune response

European strains (subsp. mycoides) less H202 than

African strains of this spp

Induce toxic damage to host cell to which the organism are adhering

Production of H202

Promote attachment to mammalian cells

Possess structures composed of unique adhesion proteins

Can adhere to ___ and ___ and can also impair ___

-neutrophils and macrophages -phagocytic functions

-Important virulence attributes - allows the organism to rapidly adapt to the host environment and to evade the developing immune response

Variation in surface proteins

Alterations in surface proteins demonstrated In many important animal pathogens including:

-*Mycoplasma mycoides* subsp. *mycoides* -*M. bovis* -*M. gallisepticum* and *M. synovial* (avian pathogens)

Leads to release of pro inflammatory cytokines including tumor necrosis factor and interleukins

Activation of macrophages and monocytes

Pathogenic mycoplasmas including those involved in pulmonary diseases

Are mitogenic for B and T lymphocytes

Effect of digitonin: -growth inhibition -growth inhibition -no growth inhibition

-*Mycoplasma* species -*Ureaplasma* species -*Acholeplasma* species

Requirement for cholesterol: -*Mycoplasma* species -*Ureaplasma* species -*Acholeplasma* species

- (+) - (+) - (-)

Urease production: -*Mycoplasma* species -*Ureaplasma* species -*Acholeplasma* species

- (-) - (+) - (-)

Colony size: -*Mycoplasma* species -*Ureaplasma* species -*Acholeplasma* species

- 0.1-0.6 mm - 0.02-0.06 mm - up to 1.5 mm

Positive for glucose fermentation

-*M. capricolum* subsp. *capricolum* -*M. mycoides* subsp. *capri*

Positive for arginine hydrolysis

-*M. capricolum* subsp. *capricolum*

Positive for phosphatase activity

-*M. capricolum* subsp. *capricolum* -*Mycoplasma agalactiae*

Positive for casein digestion

-*M. capricolum* subsp. *capricolum* -*M. mycoides* subsp. *capri*

Table 38.1 and table 38.2