Transcript C. trachomatis

Diagnostic microbiology
lecture: 17
CHLAMYDIA
Abed ElKader Elottol
MSc. Microbiology
2010
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General Characteristics
• Obligate intracellular bacteria.
• Have ribosomes like bacteria.
• Are metabolically deficient.
Morphology
• Small rounded organism.
• Multiply by binary fission.
• Cell wall consists of inner & outer membranes but differ from
that of Gram negative bacteria by absence of peptidoglycan.
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Important Species
C. psittaci
C. pneumoniae
C. trachomatis
Cultural Characters Grow in:
Yolk sac of chicken embryo
Tissue culture (McCoy cells)
PATHOGENESIS
• Infect epithelial cells of mucous membranes & lungs
Virulence is due to:
• Resistance to phagocytic killing by lysosomal enzymes
• Heat-labile toxin
• Competition with host cell for nutrients
• Host’s immune response may account for inflammation &
tissue destruction.
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C. trachomatis inclusion bodies (brown) in a McCoy cell culture .
CHLAMYDIA PSITTACI
A zoonotic respiratory disease.
Natural habitat : birds
Transmitted through inhalation of :
Respiratory secretions & dust from faeces of infected birds
Common in poultry workers
Disease : Pneumonia (Psittacosis)
Diagnosis
Isolation of organism from sputum by tissue culture
Complement fixation test to detect specific Abs
Treatment
Tetracycline in adults
Erythromycin in babies
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CHLAMYDIA PNEUMONIAE
Also known as TWAR
(TW – Taiwan & AR – acute respiratory)
Cause atypical pneumonia like Mycoplasma pneumoniae
Treatment
Tetracycline in adults
Erythromycin in babies
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CHLAMYDIA TRACHOAMATIS
15 serotypes (A-L)
C. trachomatis includes three human biovars: trachoma
(serovars A, B, Ba or C), urethritis (serovars D-K), and
lymphogranuloma venereum (LGV, serovars L1, 2 and 3).
Transmission: Through close personal contact like:
• Sexual
• Passage through birth canal
• Finger to eye or fomite to eye (Trachoma)
DISEASES
1. Trachoma
• Caused by serotypes A, B, Ba & C
• One of the leading causes of blindness in developing countries
with dry & hot weather
• Chronic conjunctivitis : leads
to scarring of eye lids and cornea
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spread by direct contact with eye, nose, and throat secretions from affected
individuals, or contact with fomites
2. Genital Tract Infections (Serotypes D-K)
• Non-gonococcal urethritis in men
• A common cause of non-gonococcal urethritis
• Mucopurrulent urethral discharge
• May progress to epidydmitis & orchitis (testes
inflamation)
• Cervicitis & Vaginitis
• Mucopurrulent vaginal discharge
• Pelvic Inflammatory Disease (PID)
• May lead to secondary infertility
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3. Neonatal Infections (Caused by serotypes D-K)
• Acquired from mother’s birth canal
• Inclusion Conjunctivitis
• Profuse mucopurrulent discharge 7-12 days after birth
• Pneumonia.
4. Lymphogranuloma Venereum (LGV)
• Caused by serotypes L1, L2 & L3
• A STD with lesions on genitalia & LNs (buboes)
5. Reiter’s Disease
An autoimmune disease caused by Abs formed against C.
trachomatis which cross react with antigens on cells of
urethra & joints(arthritis, redness of the eyes, and urinary
tract signs).
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LAB DIAGNOSIS
• Specimens from urethra, conjunctiva, sputum & cervix.
• Microscopy.
• Chlamydial “cytoplasmic inclusions” are detected by:
• Giemsa staining
• Fluorescent Ab staining
• PCR
• Cell Culture
• Sero-diagnosis
TREATMENT
Tetracycline in adults
Erythromycin or Azithromycin in babies
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Calymmatobacterium granulomatous
Klebsiella granulomatis
GRANULOMA INGUINALE
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The disease is commonly known as donovanosis
 Small, painless nodules appear after about 10–40 days of the
contact with the bacteria. Later the nodules burst, creating open,
fleshy ‫سميك‬, oozing ‫ رشح‬lesions.
General characteristics
Capsulated short Gram-negative rod
A STD with higher incidence in homosexuals
Clinical Features
Initially papules appear on external genitalia which ulcerate and
extend widely – ulcer formation
Base of ulcer is “BEEFY”; spreads by contact so is known as
“KISSING ulcers”
Lymph Nodes may enlarge
Treatment : Tetracycline
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MYCOPLASMA
An older name was Pleuropneumonia-Like Organisms PPLO
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GENERAL CHARACTERISTICS
The smallest free-living organism (0.3 μ diameter).
Have no cell wall.
Insensitive to penicillins & cephalosporins.
Poorly stained by Gram-staining.
Cytoplasmic membrane contains cholesterol.
Slow growth on specialized artificial culture media (a week).
Typical “fried-egg” appearance of colonies by a plate
microscope
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Formulae
Difco™ PPLO Agar
Approximate Formula* Per Liter
Beef Heart, Infusion from 50 g ................................... 6.0 g
Peptone ................................................................... 10.0 g
Sodium Chloride ........................................................ 5.0 g
Agar ......................................................................... 14.0 g
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MYCOPLASMA PNEUMONIAE
MAIN DISEASE
• Primary atypical pneumonia
• Common in late summer and early autumn
PATHOGENESIS & EPIDEMIOLOGY
• Droplet infection.
• Organism adhere to respiratory epithelium.
• Inhibit ciliary motion.
• Damage epithelium.
• Common in chidren & young adults
• Increased incidence in winter
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CLINICAL FEATURES
Sore throat, fever & headache.
Cough with small amount of whitish non-purulent sputum.
Some extrapulmonary symptoms.
Opacities on chest X-Rays.
IMMUNITY
Incomplete: second episode can occur.
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UREAPLASMA URELYTICUM
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Differentiated from mycoplasma due to urease enzyme
production Like mycoplasma produce “fried egg” colonies on
specialized medium.
Diseases
• Non-gonococcal, non-chlamydial urethritis in men.
• Post-partum fever in women.
• Transmitted by sexual contact.
MYCOPLASMA & UREPLASMA
LAB DIAGNOSIS
Culture : “Fried egg” colonies on specialized medium
 Cold Agglutinin detection A titer of 1:128 or higher – indicates
recent infection
TREATMENT
Tetracycline OR Spectinomycin
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RICKETTSIA & COXIELLA
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Rickettsiae
– A genus of small, rod-shaped, round to
pleomorphic microorganisms .
– gram-negative
– cultivable only in living tissues.
– Transmitted by lice‫ قمل‬and ticks‫قراد‬, they cause
disease in humans and domestic animals but are
also found in the cytoplasm of tissue cells of lice,
fleas, ticks and mites ‫سوس‬, which may act as
reservoirs and vectors
Pathogenesis
1. Insect vectors for human transmission:
arthropods such as fleas, ticks, mites ‫عث‬, or lice
2. Rodents, humans, or arthropods: all can serve as
reservoirs
3. Multiply in salivary glands of ticks & gut of
lice/fleas
4. Site of Bite = Eschar (encrusted‫ متقشر‬ulcer) →
necrotic tissue:
Site of bite = point at which Rickettsia
enters the body becomes blackened
1. Following bite, organisms taken into body
by “phagocytosis process
2. Organisms multiply in both nucleus &
cytoplasm of host cell.
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Typhus Group
Louse borne (epidemic) Typhus.
–
Etiological agent = Rickettsia prowazekii
–
Transmission: person-to-person by infected human
body louse that excretes organisms in feces
• Introduction of pathogen form lice facilitated by
scratching the louse bites
–
high fever, chills, rash possible
–
Duration of Disease: ~2 weeks; more severe in ederly
–
Complications: CNS dysfunction and myocarditis
Rock Mountain Spotted Fever
Etiological agent = Rickettsia ricketsii
Reservoir = rodents (mice, rats)
Vector = Tick Bite
Rickettsia in saliva of tick, transfer to humans after bite Human infection
High fever & malaise, then rash – initially, but becomes petechial
or hemorrhagic
Rash starts on extremities, then rapid spread to entire body.
Untreated cases – vascular disturbances with myocardial or renal
failure possible
Coxiella
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Etiological agent = Coxiella burnetti
Q fever
Reservoir = cattle, sheep, rodents, ticks
Vector = contaminated aerosol
C. burnetti enters the body via mucous membranes,
abrasions & GIT via consumption of milk for infected
animals
– Zoonosis becouse animal direclty transmits the
organism to humans
– high fever, cough, pneumonia, hepatitis – all selflimiting usually; rarely – endocarditis (scarring of
hrt. valves) and scarring of liver
– complicated by hepatitis, myocarditis, or
encephalitis
Growth characteristics
• Grow only in eukaryotic cell like
• Tissue cultures OR embryonated eggs
•
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RICKETTSIA & COXIELLA : LAB DIAGNOSIS
• Serology
• PCR
• Tissue culture
• Weil-Felix Reaction
• Antigens of several species of Rickettsiae cross-react with cell
wall O antigen of Proteus OX-2, OX-19, OX-K.
• These Proteus antigens can be used in lab to detect presence
of specific antibodies against certain Rickettsia in patients serum.
• Reaction negative in Q fever
TREATMENT
• Tetracycline
• Chloramphenicol
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End of Lecture
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