Mycoplasmas
Mycoplasmas
A group of the smallest organisms that can be free-
living in nature,
Pass bacterial filter and also grow on laboratory
media,More than 80 species,belong to
Mycoplasmatales of Mollicute,3 families can be
divided,
Mycoplasmataceae (require external cholesterol
during growth,contain Mycoplasma and Ureplasma
two genera);
Acholeplasmataceae (need not external cholesterol
during growth);
Spiroplasmataceae (can form spiral structure)
BIOLOGICAL FEATURES
? Motility,Motile by possible release and
reattachment of terminal cell organelle; no
flagella present; possess a protein
attachment factor termed P1 that interacts
with a specific cellular receptor and allows
adherence to respiratory epithelium,
? Respiration-Fermentation,Aerobes-
anaerobes,
Culture
Most aerobic; require 10%-20% human or
animal serum added to basic nutrient media
except Acholeplasma; typical colony show
fried egg apperance,
Many species are part of the normal flora
These organisms are a frequent cell culture
contaminant
? The organisms have limited biosynthetic abilities;
they require cholesterol for their cell membrane
and can generate energy via the breakdown of
arginine
? Ureaplasma requires urea to produce an
electrochemical gradient; urea is converted to
ammonia to produce ATP,
GENETICS
These bacteria have the smallest
genome of any prokaryote ( about 20%
that of E,coli) and the lowest G C
content (about 24%),
Resistance
Sensitive to osmotic presssure
resistant to thallium acetate醋酸
亚铊 in a concentration of 1:10000
which can inhibit bacteria
Transmission
M,pneumoniae is spread by close contact via
aerosolized droplets and thus is most easily
spread in confined populations (e.g.,families,
schools,army barracks),
PATHOGENESIS
? Adherence factors - The P1 Adhesin localizes at tips of
the bacterial cells and binds to sialic acid residues on
host epithelial cells.The nature of the adhesins in the
other species has not been established,Colonization of
the respiratory tract by M,pneumoniae results in the
cessation of ciliary movement,
? Toxic Metabolic Products
? Immunopathogenesis, most children are infected from 2
- 5 years of age but disease is most common in children
5-15 years of age,
M.pneumoniae
? primary atypical
pneumonia,
? Incubation,1-3 weeks
? This disease can range
from subclinical to
bronchopneumonia,often
with a gradual onset and
mild to moderate severity,A
long convalescence (4-6
weeks) and several
possible complications
(CNS,cardiac) follow acute
disease,
Clinical Findings
? U,urealyticum,M.hominis,M.genitalium
are responsible for one form of
nongonococcal urethritis,
? M,hominis is associated with pyelonephritis,pelvic
inflammatory disease and post-partum fevers,
HOST DEFENSES
? Host defenses are not well
characterized but probably involve both
humoral and cell mediated responses,
EPIDEMIOLOGY
? Mycoplasma affect a specific age distribution
(5-9 year olds) and represent 8-15% of all
pneumonias in school age children,
? Disease occurs worldwide,is endemic in
some areas and is spread by close personal
contact (schools,families),
? U,urealyticum is sexually acquired,
Antibody titers in
different age groups,
Anti-mycoplasma
pneumoniae
antibodies indicate
pneumonia caused by
this organism is
highest in the 5-15
year age group
Acquired Pneumonia Caused by Mycoplasma
pneumoniae
Microbiological diagnosis
Specimens,throat swab,sputum,genital
secretion,etc,
Microscopy - This is not particularly useful because of the
absence of a cell wall but it can be helpful in eliminating
other possible pathogens,
Culture - Sputum (usually scant) or throat washings must be
sent to the laboratory in special transport medium,It may
take 2 -3 weeks to get a positive identification,Culture is
essential for a definitive diagnosis,
Complement fixation test
Cold agglutinins - Approximately 34% - 68% of patients with
M,pneumoniae infection develop cold agglutinins,
ELISA - There is a new ELISA for IgM that has been used for
diagnosis of acute infection,
PCR
CONTROL
Sanitary,Avoidance of contacts,if
possible,
Immunological,No single vaccine is
available,Natural resistance follows
infection,
Chemotherapeutic,Tetracycline,
erythromycin or chloramphenicol are
effective,
Mycoplasma and L Form Bacteria
MYCOPLASMA L-FORM BACTERIA
No genetic relationship with
bacteria
Relate to their parent
bacteria,sometimes can
revert
Cholesterol for their cell
membrane
No cholesterol for their cell
membrane
Stable in ordinary medium Need hyperosmotic solution
Grow slowly,colony small
(diameter 0.1-0.3mm)
Colony larger(diameter 0.5-
1.0mm)
Low turbidity in liquid
medium
High turbidity in liquid
medium,may adhere to the
wall or bottom of the tube
Mycoplasmas
A group of the smallest organisms that can be free-
living in nature,
Pass bacterial filter and also grow on laboratory
media,More than 80 species,belong to
Mycoplasmatales of Mollicute,3 families can be
divided,
Mycoplasmataceae (require external cholesterol
during growth,contain Mycoplasma and Ureplasma
two genera);
Acholeplasmataceae (need not external cholesterol
during growth);
Spiroplasmataceae (can form spiral structure)
BIOLOGICAL FEATURES
? Motility,Motile by possible release and
reattachment of terminal cell organelle; no
flagella present; possess a protein
attachment factor termed P1 that interacts
with a specific cellular receptor and allows
adherence to respiratory epithelium,
? Respiration-Fermentation,Aerobes-
anaerobes,
Culture
Most aerobic; require 10%-20% human or
animal serum added to basic nutrient media
except Acholeplasma; typical colony show
fried egg apperance,
Many species are part of the normal flora
These organisms are a frequent cell culture
contaminant
? The organisms have limited biosynthetic abilities;
they require cholesterol for their cell membrane
and can generate energy via the breakdown of
arginine
? Ureaplasma requires urea to produce an
electrochemical gradient; urea is converted to
ammonia to produce ATP,
GENETICS
These bacteria have the smallest
genome of any prokaryote ( about 20%
that of E,coli) and the lowest G C
content (about 24%),
Resistance
Sensitive to osmotic presssure
resistant to thallium acetate醋酸
亚铊 in a concentration of 1:10000
which can inhibit bacteria
Transmission
M,pneumoniae is spread by close contact via
aerosolized droplets and thus is most easily
spread in confined populations (e.g.,families,
schools,army barracks),
PATHOGENESIS
? Adherence factors - The P1 Adhesin localizes at tips of
the bacterial cells and binds to sialic acid residues on
host epithelial cells.The nature of the adhesins in the
other species has not been established,Colonization of
the respiratory tract by M,pneumoniae results in the
cessation of ciliary movement,
? Toxic Metabolic Products
? Immunopathogenesis, most children are infected from 2
- 5 years of age but disease is most common in children
5-15 years of age,
M.pneumoniae
? primary atypical
pneumonia,
? Incubation,1-3 weeks
? This disease can range
from subclinical to
bronchopneumonia,often
with a gradual onset and
mild to moderate severity,A
long convalescence (4-6
weeks) and several
possible complications
(CNS,cardiac) follow acute
disease,
Clinical Findings
? U,urealyticum,M.hominis,M.genitalium
are responsible for one form of
nongonococcal urethritis,
? M,hominis is associated with pyelonephritis,pelvic
inflammatory disease and post-partum fevers,
HOST DEFENSES
? Host defenses are not well
characterized but probably involve both
humoral and cell mediated responses,
EPIDEMIOLOGY
? Mycoplasma affect a specific age distribution
(5-9 year olds) and represent 8-15% of all
pneumonias in school age children,
? Disease occurs worldwide,is endemic in
some areas and is spread by close personal
contact (schools,families),
? U,urealyticum is sexually acquired,
Antibody titers in
different age groups,
Anti-mycoplasma
pneumoniae
antibodies indicate
pneumonia caused by
this organism is
highest in the 5-15
year age group
Acquired Pneumonia Caused by Mycoplasma
pneumoniae
Microbiological diagnosis
Specimens,throat swab,sputum,genital
secretion,etc,
Microscopy - This is not particularly useful because of the
absence of a cell wall but it can be helpful in eliminating
other possible pathogens,
Culture - Sputum (usually scant) or throat washings must be
sent to the laboratory in special transport medium,It may
take 2 -3 weeks to get a positive identification,Culture is
essential for a definitive diagnosis,
Complement fixation test
Cold agglutinins - Approximately 34% - 68% of patients with
M,pneumoniae infection develop cold agglutinins,
ELISA - There is a new ELISA for IgM that has been used for
diagnosis of acute infection,
PCR
CONTROL
Sanitary,Avoidance of contacts,if
possible,
Immunological,No single vaccine is
available,Natural resistance follows
infection,
Chemotherapeutic,Tetracycline,
erythromycin or chloramphenicol are
effective,
Mycoplasma and L Form Bacteria
MYCOPLASMA L-FORM BACTERIA
No genetic relationship with
bacteria
Relate to their parent
bacteria,sometimes can
revert
Cholesterol for their cell
membrane
No cholesterol for their cell
membrane
Stable in ordinary medium Need hyperosmotic solution
Grow slowly,colony small
(diameter 0.1-0.3mm)
Colony larger(diameter 0.5-
1.0mm)
Low turbidity in liquid
medium
High turbidity in liquid
medium,may adhere to the
wall or bottom of the tube
