Transcript M. pneumoniae

Chapter 44
Mycoplasma and Ureaplasma
(黴漿菌, 尿漿菌)
Chapter 47
Chlamydiaceae (披衣菌/衣源體)
Chapter 45
Rickettsia and Orientia
Chapter 46
Ehrlichia, Anaplasma, Coxiella
Chapter 44
Mycoplasma and Ureaplasma
(黴漿菌, 尿漿菌)
Yu Chun-Keung DVM, PhD
Department of Microbiology and
Immunology
5 families, 200 species; 16 colonize
humans and 5 associated with diseases
Mycoplasma (黴漿菌)
M. pneumoniae
M. hominis
M. genitalium
M. fermentans
Ureaplasma (尿漿菌)
U. urealyticum
Smallest (0.1-0.3 m) and simplest freeliving bacteria (about twice the genome size
of certain large viruses)
Lack a cell wall (highly pleomorphic),
resistant to penicillin, cephalosporins,
vancomycin, sensitive to tetracycline,
erythromycin.
Cell membrane contains sterols - rigid
Anaerobic (except M. pneumoniae)
Grow slowly in cell-free media, need sterols,
use glucose as a source of energy
(ureaplasmas require urea)
Small, fried-egg-like colonies (except M.
pneumoniae)
Epidemiology
M. pneumoniae
Worldwide disease with no seasonal
incidence
Most common in school-age children
and young adults (5-10y), but all age
groups are susceptible
Spread by nasal secretions in close
contact among classmate or family
members
U. urealyticum, M. hominis, and M.
genitalium
Infants (females) are colonized with the
agents at birth
Only a small proportion of prepubertal
children remain colonized
The incidence of genital mycoplasmas is
associated with sexual activity

Sexually active men and women 15% with M.
hominis and 45-75% with Ureaplasma
Pathogenesis
Extracellular pathogen;
infect and colonize
mucous membrane; do
not invade other tissues.
M. pneumoniae adheres to
sialated glycoprotein receptor
at the base of cilia (and on
surface of RBC) by means of
P1 antigen.
The mechanism of cellular damage is
unknown (produce peroxidase and
hemolyze RBC?)
Causes ciliostasis, destroy cilia and
ciliated epithelial cells; breakdown
clearance activity, lead to LRT infection
and persistent cough.
M. pneumoniae contains superantigen,
can attract inflammatory cells and induce
cytokine secretion (TNF, IL-1, IL-6).
Clinical disease
• Cause mild URT disease, low-grade fever,
malaise, headache, dry and nonproductive
cough, persist for > 2 weeks
• 10% patients develop LRT symptoms:
tracheobronchitis, atypical (walking)
pneumonia
• Secondary complication: otitis media,
erythema multiforme (Stevens-Johnson
syndrome), myocarditis, pericarditis
Typical pneumonia - bacterial pneumonia
Abrupt, rigorous onset
Productive cough,
purulent sputum
High fever, chest pain,
stiffness in the neck
Chest consolidation
and rales.
Murray, et.al: Textbook of
Respiratory Medicine
Atypical (walking) pneumonia
Flulike symptomes generalized aches,
discomfort, headache,
chill, dry cough, lowgrade fever
Chronic in both onset
and recovery
Chest radiographs:
patchy bronchopneumonia interstitial
pattern, not
pneumonia
Murray, et.al: Textbook of Respiratory
Medicine
U. urealyticum and M. genitalium:
cause nongonococcal urethritis
M. hominis:
implicated as a cause of pyelonephritis,
pelvic inflammatory disease, and
postpartum fever
Lab diagnosis
Culture of mycoplasmas is not routinely
attempted, and relatively insensitive

M. pneumoniae can grow in special medium
with animal serum (sterols), yeast extract,
glucose, and penicillin. Colonies have a
“mulberry-shaped”.

M. hominis requires arginine for growth.
Colonies have a fried-egg appearance.

Ureaplasma requires urea for growth
Microscope: no cell well, stain poorly, no
value
Serology - M. pneumoniae
Complement fixation test : high falsepositive rate
ELISE for detection of IgM and IgG Abs
Nonspecific reaction to outer membrane
glycolipids : cold agglutinins:

IgM Abs that bind the I antigen on human RBC
at 4°C) develop in 65% of the patients - a test
frequently used to confirm the diagnosis.

False-positive seen in infections with EpsteinBarr virus, cytomegalovirus, and adenovirus.
Treatment
M. pneumoniae: erythromycin,
tetracycline (also good for
chlamydia)
Ureaplasma: use erythromycin,
resistant to tetracycline
M. hominis: resistant to
erythromycin and tetracycline, use
clindamycin
Chapter 47
Chlamydiaceae (披衣菌, 衣源體 )
Yu Chun-Keung DVM, PhD
Department of Microbiology
and Immunology
Family Chlamydiaceae
Genus Chlamydia:
C. trachomatis (砂眼披衣菌)
Genus Chlamydophilia:
C. pneumoniae (肺炎披衣菌)
C. psittaci (鸚鵡熱披衣菌)
Chlamydiaceae
Obligate intracellular organisms,
were once considered virus.
Possess inner and outer membranes
Contain DNA and RNA
Possess ribosomes
Synthesize proteins, nucleic acid, and
lipids, but cannot synthesize ATP.
Respond to wide-spectrum antibiotics,
but not to penicillin (lack peptidoglycan)
Unique development cycle
Two morphological distinct
forms in cytoplasmic
phagosome:
(1) elementary body (300-400
nm), resistant to harsh
environmental factor; bind to
receptors of host cells and
stimulate uptake; metabolically
inactive but infectious,
(2) reticulate body (800-1000
nm), reproductive form, divide
by binary fission,
Histologic stains can detect phagosome
noninfectious.
with accumulated RBs (inclusion)
1. Chlamydia trachomatis (砂眼披衣菌)
Infections only occur in humans
Two biovars (trachoma and LGV) and
19 serotypes (antigen differences in MOMP)
Serotypes
A to C
D to K
L1 to L3
Disease
Trachoma
Urethritis, cervicitis
Inclusion conjunctivitis
Neonatal conjunctivitis
Infant pneumonia
Lymphogranuloma venereum
Pathogenesis
EBs enter the body via minute abrasions and
lacerations
Primarily infect nonciliated columnar, cuboidal, or
transitional epithelial cells (urethra, endocervix,
endometrium, fallopian tube, anorectum,
respiratory tract, conjunctiva)
LGV biovar replicate in mononuclear phagocytes
in lymphatic system (formation of granuloma,
abscesses, or sinus tracts in LN draining the site
of primary infection)
Pathogenesis
Destruct cells during replication
Infection stimulates a severe
inflammatory response (neutrophils,
lymphocytes and plasma cells).
No long-lasting immunity after infection
Re-infection induces a vigorous
inflammatory response with subsequent
tissue damage (blindness and sterility).
Trachoma (砂眼)
A chronic suppurative eye disease caused by
serotypes A,B,Ba,C.
Follicular conjunctivitis →scar →corneal
ulceration →pannus formation (翳, 音易)
(invasion of vessels into the cornea,) →blindness
Endemic in the Middle East, North Africa, and
India (dry and sandy regions); predominantly in
children. Leading global causes of blindness
(500 million infected, 7 to 9 million blinded).
Transmission: eye-to-eye by droplet, hands,
contaminated clothing, flies.
Urogenital infections
Venereal infections caused by serotypes of
D to K.
The most common sexually transmitted
bacterial disease in U.S. 2.8 million new
cases annually, largely in males (50 million
worldwide).
In women: 80% asymptomatic; bartholinitis,
cervicitis, pelvic inflammatory disease,
which can lead to sterility and ectopic
pregnancy.
In men: 25% asymptomatic; nongonococcal
urethritis (NGU)
Nongonococcal
urethritis
1. Mild
2. Slow and prolonged
3. Dysuria is mild
4. Urethral discharge is
clear or white, thin
and mucoid
Gonorrhea
1.
2.
3.
4.
Severe
Acute
Severe dysuria
Purulent
discharge
Nongonococcal Urethritis (NGU)
Urethritis caused by pathogens other
than gonococcus
C. trachomatis (35-50% of cases)
Ureaplasma urealyticum (10-30% of cases)
Mycoplasma hominis
Gardnerella vaginalis
Trichomonas vaginalis
Candida albicans
Herpesvirus hominis (?)
Cytomegalovirus (?)
Adult Inclusion Conjunctivitis
(成人包涵性結膜炎)
Acute follicular conjunctivitis with
mucopurulent discharge
Mostly occur in sexually active
adults (18-30 yr) with genital
infection with serotypes A, B, Ba, D
to K.
Auto-inoculation, oral-genital contact
Newborn Inclusion Conjunctivitis
25% infants acquired from
mothers with active genital
infections
Long (>12 months) disease
course if untreated and are at
risk for C. trachomatis
pneumonia
Infant Pneumonia
A diffuse interstitial pneumonia
Occur in 10-20% infants that
exposed to the pathogen at
birth
Rhinitis → staccato cough
(afebrile)
Lymphogranuloma venereum (LGV)
花柳性淋巴肉芽腫
A chronic sexually transmitted disease caused by
C. trachomatis L1, L2, L2a, L3.
More common in men, with male homosexuals
being the major reservoir.
Small, painless lesions at site of infection
(genitalia). Fever, headache, myalgia.
Swelling of regional lymph nodes (inguinal nodes),
painful buboes (橫瘻), rupture.
Proctitis is common in women.
Resolve spontaneously or progress to ulceration
or genital elephantiasis (象皮病).
Bubonic plague – Inguinal buboes with edema
Lab diagnosis
Symptomatic infections are easier to
diagnosis than asymptomatic infections
Cytology – Giemsa-stained cell scrapings

Quality of the specimen is important.
Specimens must be obtained from the involved
site; pus or exudate is inadequate.

Insensitive, nonspecific
Culture – HeLa, MaCoy, Hep-2 cells; iodine
strain to detect inclusions; the most specific
methods for diagnosis.
Iodine-stained Chlamydia trachomatis inclusion
bodies (arrows)
Chlamydial urethritis (elementary bodies in
direct smear of urethral cell, fluorescein antibody
stain)
Lab diagnosis
Nucleic acid amplification tests (NAATs) –
test of choice for lab diagnosis of C.
trachomatis infection
Serologic tests – limited value for adult
urogenital infections; good for LGV.

CF test or EIAs: genus-specific LPS, fourfold
increase or >1:256

MIF test: species- and serovar-specific antigen
(MOMPs)
2. Chlamydophilia pneumoniae
(肺炎披衣菌)
Was first isolated from the conjunctiva of a
child in Taiwan - TWAR stain.
An important cause of bronchitis,
pneumonia and sinusitis.
Infection is common, especially in adults
and transmitted person-to-person by
respiratory secretions.
Clinical disease
Most infections are asymptomatic or mild
- persistent cough.
Can’t be differentiated with other atypical
pneumonia - M. pneumoniae, Legionella
pneumophila, and respiratory viruses.
Detected in atherosclerotic lesions in
blood vessels. However, the role in the
development of atherosclerosis is not
clear.
(Koch’s postulate)
Lab diagnosis
Diagnosis is difficult
Do not grow in cell lines
NAATs are OK for use.
Complement fixation test (not
specific) or MIF test (specific)
3. Chlamydophilia psittaci
(鸚鵡熱披衣菌)
Caused Psittacosis (parrot fever).
The natural reservoir is any species
of birds (Ornithosis,飼鳥病)
Veterinarians, zookeepers, pet shop
workers, employees of poultry
industry.
Pathogenesis
Inhalation of dried bird excrement, urine, or
respiratory secretions; person-to-person
transmission is rare.
Bacteria spread to and multiply in
reticuloendothelial cells of liver and spleen 
necrosis
Disseminate to lung and other organs via
circulation
Lmphocytic inflammation in lung, edema,
necrosis, mucous plugs  cyanosis and anoxia
C. psittaci has three forms of
infection
Asymptomatic infection
Transient flu-like illness: high fever,
headache, chills, myalgia
Serious pneumonia: non-productive
cough, rales, CNS involvement is
common, carditis, hepatomegaly,
splenomegaly
Diagnosis and treatment for
C. psittaci
Diagnosis: complement fixation
test with group antigen, fourfold
rise in specific antibody
Treatment: tetracyclines or
macrolides
Treat birds with chlortetracycline
HCl for 45 days.
C. trachomatis
C. pneumoniae
C. psittaci
Disease severe
Glycogen absent
No staining with iodine
Disease mild and chronic
Glycogen in inclusions
Inclusions can be stained
with iodine
Susceptible to sulfonamides Sulfonamide resistant
Chapter 45
Rickettsia and Orientia
Chapter 46
Ehrlichia, Anaplasma, Coxiella
Rickettsia Howard Ricketts
Ehrlichia
Paul Ehrlich
Coxiella
Harold Cox
(Historically classified in Rickettsiaceae)
Order Rickettsiales
Family Rickettsiaceae
Genena Rickettsia
Orientia
Family Anaplasmataceae
Genena Ehrlichia
Anaplasma
Neorickettsia
Wolbachia
Chapter 45
Rickettsia and Orientia
General characteristics
G(-) bacilli, obligate intracellular
parasites.
Were thought to be virus: small
(0.3x1m), 800 genes.
True bacteria: DNA+RNA, binary fission,
sensitive to antibiotics, use host cell ATP.
Maintain in animal and arthropod
reservoirs.
Transmitted to humans by arthropod
vectors (ticks, mites, lice, fleas), and
maintained in arthropod hosts by
transovarian transmission.
Humans are accidental hosts: acquired
by arthropod bite or contact of
arthropod excreta with abraded skin.
The distribution of rickettsial diseases is
determined by the distribution of the
arthropod host/vector.
Pathogenesis
Rickettsia (also Ehrlichia) is unstable and die
quickly outside host cells.
Coxiella highly resistant to desiccation, remain
viable in environment for months to years.
No toxins, no immunopathology
Rickettsia replicate in endothelial cells,
cause cell damage and blood leakage, skin rash,
microthrombi, focal ischemia, hemorrhage.
Hypovolemia, hypoproteinemia, reduced
perfusion, organ failure.
Important Rickettsial Diseases
Spotted fever group
R. rickettsii
R. akari
RMSF (>90%)
Rickettsialpox (100%)
Typhus group
R. prowazekii
R. typhi
Epidemic typhus (40-80%)
Murine typhus (50%)
Scrub typhus group
O. tsutsugamushi Scrub typhus (<50%)
(Parentheses: % of rash, 紅斑)
Spotted fever 斑疹熱
Have a restricted geographic distribution; Rocky
mountain spotted fever (RMSF) is the prototype
of the group, caused by R. rickettsii.
Organisms are maintained in hard ticks (wood
tick and dog tick) by transovarian transmission.
Transmitted to humans by ticks (need 24-48h
to establish infection).
High fever, chills, headache, skin rash (>90%,
extremities to trunk)
GI symptoms, respiratory failure, encephalitis,
renal failure.
Diagnosis is urgent, because the
prognosis depends on the duration of
illness. (identify key clinical signs – rash)




Culture: tissue culture or embryonated eggs
(danger)
Microscopy: Giemsa stain; FA for biopsy
tissue specimens (rapid and specific)
Serology: Microimmunofluorescence (MIF),
detect antibodies against MOMP and LPS
antigens
Molecular diagnosis: PCR, not speciesspecific
Prevention/Control:
Tetracyclines (e.g., doxycline)
No vaccine
Prevent tick bites (can survive for
as long as 4 years without feeding)
Epidemic (louse-borne) typhus
流行性(蝨型)斑疹傷寒
R. prowazekii transmits from man to man by
human head and body lice.
Humans are the primary reservoir (lice die 2 to 3
wk after infection).
Epidemics occur among people living in crowded,
unsanitary condition - war, famine, or natural
disaster.
High fever, severe headache, chills, followed by a
generalized skin rash; complications: myocarditis
and CNS involvement.
O
Brill-Zinsser Disease
A recrudescent form of
epidemic typhus arising
years after the initial attack.
Diagnosis:

MIF test
T/P/C:

Tetracyclines, Chloramphenicol

Louse-control

Formaldehyde-inactivated vaccine
Endemic (murine) typhus
地方性(鼠類)斑疹傷寒
R. typhi transmits to man from
rodents reservoir hosts by rat flea.
Endemic all over the world, primarily
in warm, humid areas.
Fever, severe headache, chills, skin
rash (50%) on chest and abdomen
o
Diagnosis:

IFA test
T/P/C:

Tetracyclines, doxycycline,
Chloramphenicol

Pest control

No vaccine
Scrub typhus 叢林斑疹傷寒
A rickettsial disease caused by Orientia
tsutsugamushi (恙蟲病立克次體菌)
Transmitted to humans by red mites (chiggers)
Organisms are maintained in mites by
transovarian transmission.
Endemic in eastern Asia, Australia, and Japan.
Fever, severe headache, skin rash (<50%),
spread centrifugally to extremities.
Generalized lymphadenopathy, splenomegaly,
CNS complication, heart failure
O
別來無恙？
歲亦無恙耶？
民亦無恙耶？
王亦無恙耶？
<國策>「齊策‧四」
T/P/C:

Prompt treatment with
tetracyclines, doxycycline,
chloramphenicol

Avoid exposure to chiggers

No vaccine
Chapter 46
Ehrlichia, Anaplasma, Coxiella
Ehrlichia and Anaplasma
Intracellular bacteria that
lodge in phagosomes of
mononuclear and
granulocytic phagocytes,
but not RBC.
multiply in phagosomes
= morulae
Grow cycle: three stages elementary body, initial body,
morula
Ehrlichia inclusions (peripheral blood smear, Wright-Giemsa)
Clinical disease
Human monocytic ehrlichiosis
E. chaffeensis : infect blood monocytes
and mononuclear phagocytes in tissues
and organs
Vector - Lone Star tick
Reservoir - white-tailed deer, domestic
dogs
Canine granulocytic ehrlichiosis
E. ewingii
Vector - Lone Star tick
Reservoir -white-tailed deer, domestic dogs.
Human anaplasmosis
Anaplasma phagocytophilium : infect
bone marrow myeloid cell (i.e., neutrophils)
Vector - Ixodes ticks
Reservoir - small mammals
Clinical disease
Fever, headache, malaise, leukopenia,
thrombocytopenia
Skin rash (10 to 40%)
50% patients require hospitalization,
1 to 3% mortality
T/P/C:
Diagnosis is urgent. Prompt
treatment with doxycycline
No vaccine
Avoid tick-infested areas
Coxiella burnetii 蒲奈氏科克斯菌
Biologically and genomically distinct
from Rickettsia; more closely related
to Legionella and Francisella.
Obligate intracellular pathogen
Multiply in phagolysosome
Epidemiology
Can infect mammals, birds, and ticks
Primary reservoirs: farm animals, cats,
dogs, rabbits
Ticks are vector for disease in
animals but not in humans
Epidemiology
High concentrations of bacteria are present
in placenta of infected livestock.
Spores are able to survive in nature under
dry environmental conditions for months.
Transmit to man by the respiratory route
from contaminated soil, not from
arthropod vector.
Those handling pregnant or lactating cows
or sheep, drinking unpasteurized milk, or
working in slaughter-houses are at highest
risk.
Pathogenesis
Target tissue is the lung, proliferate in
phagolysosomes of infected cells, then
disseminate to other organs
Undergo antigenic variation (cell wall LPS):
phase I antigen: LPS with a complex
carbohydrate, can block antibody binding;
infectious form
phase II antigen: modified LPS, expose surface
proteins to antibody, less infectious form
Formation of immune complex: cause of signs
and symptoms
Q fever
Most infections are mild or asymptomatic
Acute disease:


Pneumonia - high fever, severe headache, chill,
myalgias, resemble “atypical pneumonia”
Granulomatous hepatitis, hepatosplenomegaly,
Chronic disease: subacute endocarditis
with long incubation period and poor
prognosis
Diagnosis
Serologic tests (IFA, ELISA, CF)
Acute Q fever: IgM and IgG are
developed against phase II antigen.
Chronic Q fever: antibodies against both
phase I and II antigens are elicited.
(phase I antigen: weak antigenic)
T/P/C:
Doxycycline for prolonged period
Vaccine is available (single dose
with no booster immunization for
uninfected people)
96.5.14