Download 4_Mycoplasma, Ureaplasma and Chlamydia

ZaidKhalid MBBS220
Mycoplasma, Ureaplasma and Chlamydia
Mycoplasma
General characteristics
1. Small free-living bacteria
2. Highly pleomorphic
3. Doesn’t have cell wall
a. Bounded by a triple layered unit membrane that contains
sterols
4. Can pass thru 0,.45um filter
a. Once thought to be virus
5. Grow slowly, generation time 1 – 6 hours
6. Formed small colonies; fired egg like appearance
7. Resistant to cell wall disrupting antibiotics
a. Penicillin
b. Cephalosporins
8. Have affinity to mammalian cell membranes
9. Important species
a. M pneumoniae
b. M hominis
c. M genitalium
Clinical Diseases
Mycoplasma pneumoniae
1. Strict human pathogen
2. Transmitted thru infected respiratory
secretions
3. Initiated by attachment to tip of a
receptor on the surface of respiratory
epithelial cells
a. Attachment by specific adhesion
protein
4. During infection, bacteria remains
extracellular
Mycoplasma hominis
1. Associated by various diseases
2. Can be cultured from upper urinary
tract
a. 10% of patients with pyelonephritis
3. Strongly associated with infection of
pelvic inflammatory disease
5. Causing
a. URTI
i. Low grade fever
ii. Malaise
iii. Headache
iv. Dry, non-productive cough
v. Develop 2-3 weeks after
exposure
b. LRTI
i. Tracheobronchitis
ii. Atypical pneumonia
a. Uterine tubes
b. Tubo-ovarian abscesses
4. Has been isolated form blood of pts
with
a. Post abortal
b. Post-partum fever
Mycoplasma genitalium
1. One of the causes of non-gonococcal urethritis
Pathogenicity
Virulence factors
1. Possesses adhesion
protein P1
a. Bind to the base
cilia of epithelial
cells
b. Lead to eventual
loss of ciliated
epithelial cells
c. Acts as
superantigen
i. Stimulates the
migration of
inflammatory
cells
ii. Release of
cytokines
Treatment
DOC
1. Erythromycin
2. Doxycycline
3. Tetracycline
All are effective in
combating
mycoplasma
Though tetracycline
reserved for only adults
ZaidKhalid MBBS220
Ureaplasma
General characteristics
1. Colonies are extremely small
a. Formerly called the T strains for tiny colonies
2. Requires 10% of urea for growth
3. Important species
a. Ureaplasma urealyticum
4. Can be distinguished from mycoplasma thru production of urease
5. Cultured in liquid media of urea and phenol red
a. Growth of bacteria resulting in the release of ammonia from urea
i. Increase in pH
ii. Change in colour as indicator
Clinical Diseases
Ureaplasma urealyticum
1. Common in female genital tract
2. Associated with lung disease
a. In premature low-birth weight infants
b. Acquired the organism during birth
3. One of the causes of non-gonococcal urethritis in men
Treatment
DOC
1. Erythromycin
a. U urealyticum is resistant towards
tetracycline
ZaidKhalid MBBS220
Chlamydiaceae
General characteristics
1. Consists of 2 genera
a. Chlamydia
i. Chlamydia trachomatis
1. Grows in cell culture
a. HeLA-229
b. McCoy
c. BHK21
2. Subdivided into 2 biovars
a. Biovar trachoma
i. 15 serovars
b. Biovar LGV
i. 4 serovars
c. Serovars
i. A,B,Ba,C
1. Primarily conjunctiva
ii. D-K
1. Primarily urogenital tract
iii. L1-13
1. Inguinal lymph nodes
b. Chlamydophila
i. Chlamydophila psittaci
ii. Chalmydophila pneumoniae
2. Once regarded as virus cause
a. Can pass thru 0.45um filters
b. Obligate intracellular parasites
3. Exist in two morphologically distinct forms
a. Infectious elementary body
b. Larger non-infectious reticulate body
ZaidKhalid MBBS220
Clinical Diseases
Chlamydia trachomatis
1. Trachoma
a.
Chronic disease caused by serovars
i. A
ii. B
iii. Ba
iv. C
b. Presents with conjunctivitis with diffuse inflammation
c. Involves the
i. Entire conjunctiva
ii. Corneal ulceration
iii. Scarring
iv. Pannus formation (invasion of blood vessels into the cornea
2. Adult inclusion conjunctivitis
a.
Acute follicular conjunctivitis associated by genital infections
i. A
ii. B
iii. Ba
iv. D-K
b. Characterised by
i. Mucopurulent discharge
ii. Keratitis
iii. Corneal infiltrates
3. Neonatal conjunctivitis
i. Cervicitis
ii. Endometritis
iii. Urethritis
iv. Salphingitis
v. Bartholinitis
vi. Perihepatitis
c. Genital infection in men is symptomatic
i. Present with urethritis
d. Reiter’s syndrome
i. Characterised by
1. Urethritis
2. Conjunctivitis
3. Polyarthritis
4. Mucocutaneous lesions
ii. Believed to be initiated by genital infections
7. Lymphogranuloma venereum
a.
b.
i.
ii.
iii.
iv.
a.
b.
Exposure to the bacteria at birth
Characterised by
i. Swelling
ii. Hyperemia of the eyelids
iii. Copious purulent discharge (many discharge)
v.
4. Infant pneumonia
a.
b.
Onset within 2-3 weeks after birth
Rhinitis observed followed by a distinctive staccato cough
vi.
5. Ocular lymphogranuloma venereum
a.
i.
LGV serotypes have been implicated in Parinaud’s oculoglandular conjunctivitis
Conjunctival inflammation associated with
1.
Preauricular
2. Submandibular
3. Cervical lymphadenopathy
6. Urogenital infections
a.
b.
In women is asymptomatic
Symptomatic cases may present with
c.
d.
i.
ii.
Sexually transmitted infection serovar L1-3
Characterised by
Transient genital lesion
Followed by multiocular suppurative involvement of the inquinal lymph node
Nodes initially discrete but progress to
1. Matted
2. Suppurative (bubos)
Skin over the node may be
1. Thinned
2. Multiple draining fistulas
Systemic symptoms of
1. Fever
2. Chills
3. Headache
4. Arthralgia
5. Myalgia
Late complication include
1. Urethral or rectal strictures
2. Perirectal abscesses
3. Fistulas
Primary genital lesion is usually
Small painless ulcer/papule
Heals within few days, may be unnoticed
Most common complaint is lymphadenopathy
ZaidKhalid MBBS220
Clinical Diseases
Chlamydophila psittaci
1. Causes human psittacosis (ornithosis)
a. Zoonosis contracted thru inhalation of
i. Respiratory secretion
ii. Dust from the droppings of infected birds
2. Causes an acute infection of lower respiratory tract, presenting the onset of
a. Fever
b. Headache
c. Malaise
d. Muscle aches
e. Dry hacking
f. Cough
g. Bilateral interstitial pneumonia
3. Occasionally develop into systemic complications
a. Myocarditis
b. Encephalitis
c. Hepatitis
Chlamydophila pneumoniae
1. Spread thru respiration droplets
2. Not like psittacosis, birds are not the reservoir
3. Most infections present with
a. Pharyngitis
b. Lower respiratory disease
c. Or both
4. Clinical spectrum is the same with M pneumoniae infection
5. Pharyngitis/laryngitis may occur within 1-3 weeks prior to bronchitis/pneumonia
a. Cough persists for weeks
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Cell Wall Defective Bacteria
Protoplasts and Spheroplasts
1. Removal of bacterial cell wall can be accomplished by
a. Hydrolysis with lysozyme
b. Blockage of peptidoglycan biosynthesis with antibiotic
2. In osmotically protective media, it will generate
a. Protoplasts from gram positive cells
b. Spheroplasts from gram negative cells
3. Spheroplasts
a. Retained outer membrane
b. Entrapped the peptidoglycan
L-phase variants (L forms )
1. Cell wall defective microbial forms that can replicate
serially on solid media as
a. Non rigid cells
b. Produce colonies
2. L forms
a. Some are stable
b. Others are
i. Unstable
ii. Revert top bacterial parental forms
3. Factor determines the revert
4.
5.
6.
7.
a. Presence of residual peptidoglycan
b. Acts as primers in its own biosynthesis
Not genetically related to Mycoplasma
Result from direct mutation or effects of antibiotic
a. This may produce chronic infections
b. The organism remains sequestered in protective
regions of the body
Some L forms are resistant to antibiotic
a. Develop difficulty in chemotherapy
Their reversion into bacillary form can produce relapses
of the overt infection