MYCOPLASMA
INTRODUCTION
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? Mycoplasma coming under the class
Mollicutes.There are 9 genera in the
class Mollicutes. Thus class Mollicutes
have 3 families are Mycoplasmataceae,
Acholeplasmataceae,Anaeroplasamataceae . From that 9 genera , 5 are veterinary importance (Mycoplasma, Ureaplasma,
Acholeplasma,Anaerplasma,Asteroplasma) .There are 100 spp in the Mycoplasma genus .First Mycoplasma identified in 1890 was Mycoplasma mycoides subsp mycoides .Similar types of Mycoplasmas were
subsequently identified called as Pleuro Pneumonia Like Organisms (PPLO).Mycoplasma is a genus of bacteria that lack a cell
wall around
their cell membrane.1 Without a cell wall, they are
unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall
synthesis.
? Generally Mycoplasma are Prokaryotes
, have capable of replication. Pleomorphic organisms which will appear as spherical , filaments .They do not have cell
wall so they cannot synthesizes
peptidoglycan .However they have 3
layered flexible outer membrane
which will causes the flexibility property of that organism . Flexibility
: Allows to pass
through bacterial membrane filters (0.22 to 0.45µ) .Sensitive to heat , dessication, detergents
but they resistant to penicillin
HABITAT: –
Mycoplasma organisms
found on mucosal surfaces of conjunctiva ,nasal cavity, oro-pharynx,intestinal, genital tract . these
are extracellular organisms.Generally host specific in nature.
PATHOGENESIS: –
Parasitic
mycoplasms tend to adhere firmly to host
‘ s mucous membrane (adhesin)
. There they produce
haemolysins, proteases, nucleases, other lethal factors that leads to
death of cells. Some
mycoplasmal organisms have predilection
site in mesenchymal cells – joints, serous cavities. Respiratory tract and lungs – frequent site of the pathogenic organisms
. It destroys the cilia of respiratory tract thereby causes
2° bacterial invasion .Latency
can occur in that microbial pathogenecity .Stress , intercurrent infection & age
predisposes the disease .Infections
may be chronic or low grade and they
are exogenous or endogenous
LABORATORY DIAGNOSIS: –
Specimens :
? Samples are fragile in nature , it should be kept at refrigerated condition and delivered to a laboratory within
24 – 48 hours of collection .Samples :Mucosal scrapings, tracheal exudates, aspirates, pneumonic tissue from the edge of
lesionCavity or joint fluids, mastitis milk
Isolation : –
Mycoplasma
are fastidious organisms, facultative anaerobes, 5-10% CO?. It requires enriched media for
growth .Basic medium is a good quality beef infusion with supplements
pH of the medium – 7.2 to 7.8. Commercially
available agar or broth (supplemented with horse serum 20% and yeast extract
with amino acid).Penicillin – inhibition of gram +ve, Thallous acetate-
inhibition of gram –ve . Specimen should be inoculated into 2 broths
(2 agar plates 1 for mycoplasm,1 for ureaplasm).Fluid material (fetal fluids ,
exudates)- directly inoculated into broth and agar medium. Some specimens
(semen, joint fluids, tissues) contain inhibitors of mycoplasms. Both undiluted
specimen & ten fold dilutions in mycoplasmal broth should be cultured
IDENTIFICATION: –
Differentiation from bacterial L
forms :
? Some bacteria temporarily failed to form cell walls (L
forms) can produce microcolonies similar to the mycoplasms . Staining of microcolonies with Diene ‘s stain – aids in
differentiation between L and mycoplasmal colonies .Mycoplasmal colonies retain stain L form
decolorise within 15 mins
COLONIAL MORPHOLOGY: –
Microscopically
:
? Appear as
fried egg colonies. Diene
‘s stain – recognizes microcolonies .
Inoculated agar plates placed
in a humid atm. at 37°C
IDENTIFICATION OF THE GENUS: –
Sensitivity to digitonin :
? Mycoplasma and urea plasma are
sensitive to digitonin.Done
by digitonin disc applied on the agar media .Positive – Zone of inhibition should be 5 mm or
more
IDENTIFICATION OF SPECIES: –
Fluorescent antibody staining:To identify M.dispar and Ureaplasm – bronchial epithelium of calves
FA (direct
and indirect) for staining mycoplasmal colonies and for recognizing mixed cultures.Commonly used in avian mycoplasms.Enzyme
linked immunoperoxidase: Porcine
bronchial epithelium – M.hyopneumoniae . AGID- Using known antisera to detect
mycoplasmal ag .ELISA – ag identification with known antisera .Species
specific DNA probes are
available.
Antibiotic susceptibility:Although it develop resistant to antimicrobial drugs .So ABST not usually performed
.Tylosin, tetracyclin,
tiamulin, fluroquinolones used for treatment .Specific pathogen
free (SPF ) programmes established for poultry and pig herds.There are 2
phases in these programmes 1)Detection of infections and culling or isolation of affected animals.2)Followed by serological monitoring
of the flocks to demonstrate continued freedom from infection
CBPP:-CHARACTERISTIC STANCE – Head, neck,extended and
elbow abducted .Post
mortem lesions are marbled
appearance lung . Grey
,red consolidated lobules alternate irregularly with pink emphysematous lobules.Chronic : fibrinous encapsulation of
necrotic foci (viable mycoplasms).Break down of capsules is major factor in the persistence
and spread of CBPP. Joints – fibrin in
synovial space & articular cartilage erosion
CCPP: –
? Highly contagious disease.Incubation period : 6-10 days Transmission is by direct contact.Post mortem
lesions are granular lung appearance and fibrinous pneumonia
CRD: –
? Highly versatile and successful
pathogen . Once infected, it remains for lifeTransmission is mainly Vertical transmission. Economically significant disease. Post mortem lesions are Sinusitis,conjunctivitis, tracheitis with
excessive mucous , air sacculitis , pneumonia , synovitis, osteomyelitis