MYCOPLASMA : ? Samples are fragile in nature ,

MYCOPLASMA SPECIES

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
lesion , cavity 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 positive, Thallous acetate- inhibition of gram negative . 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:

Microscopic examination:-

?  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

 

CLINICAL INFECTIONS

Contagious
bovine pleuropnumonia caused by M.mycoides subsp.mycoides(small colony
type),Contagious caprine pleuropneumonia caused by M.capricolum
subsp.capripneumoniae ,Contagious agalactiae of sheep and goats are caused by
M.agalactiae, Enzootic pneumonia of pigs are caused by M.hyopneumoniae, Chronic
respiratory disease caused by M.gallisepticum, Feline infectious anaemia caused
by M.haemofelis.

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 life. Transmission is mainly Vertical transmission. Economically  significant disease. Post mortem  lesions are Sinusitis,conjunctivitis, tracheitis with
excessive mucous , air sacculitis , pneumonia , synovitis, osteomyelitis