24/02/2008Dr Ekta, Microbiology, GMCA CHLAMYDIA II MBBS.
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Transcript of 24/02/2008Dr Ekta, Microbiology, GMCA CHLAMYDIA II MBBS.
24/02/2008 Dr Ekta, Microbiology, GMCA
CHLAMYDIA
II MBBS
24/02/2008 Dr Ekta, Microbiology, GMCA
KEY WORDS
IntracellularEnergy parasitesElementary bodyReticulate bodyInclusion bodies – HP, LCLBiotypes/ serotypesTissue cultureC. trachomatis
Trachoma
Inclusion conjunctivitisLymphogranuloma venereumFrei testGenital chlamydiasisC. psittaci
PsittacosisOrnithosisC. pneumoniae
24/02/2008 Dr Ekta, Microbiology, GMCA
INTRODUCTIONObligate intracellular parasites of humans, animals & birds
Resemble bacteria except it cannot multiply outside living cells/ tissues (like viruses)
Cannot synthesize ATP – depends on host cell for energy & nutrient sources. Hence, called Energy Parasites.
24/02/2008 Dr Ekta, Microbiology, GMCA
CHLAMYDIA
4 species in the Genus Chlamydia – C. trachomatis, C. pneumoniae, affects humans C. psittaci and C. pecorum affects ruminants
All are non-motile, gram negative; share antigens, have both DNA and RNA.
24/02/2008 Dr Ekta, Microbiology, GMCA
ClassificationC.trachomatis : eye & genital infections, infant pneumonia, and LGV (Lymphogranuloma Venereum) in adults
C.pneumoniae : different types of respiratory infections.
C.psittaci : psittacosis in man, ornithosis in birds
24/02/2008 Dr Ekta, Microbiology, GMCA
Life cycle Chlamydiae occur in 2 forms :
1. Elementary body – extracellular, infective form2. Reticulate body – intracellular, growing & replicative
form
• Chlamydial microcolony within the host cell is called Inclusion body.
• Mature inclusion body contains 100 - 500 elementary bodies
24/02/2008 Dr Ekta, Microbiology, GMCA
24/02/2008 Dr Ekta, Microbiology, GMCA
Life cycle
C. psittaci – host cell is severely damaged, EBs are released within 48 hrs by cell lysis
C.trachomatis – mature inclusion body appears to be exocytosed in 72- 96 hrs.
24/02/2008 Dr Ekta, Microbiology, GMCA
Antigenic Properties
Three major Ags1. Genus specific Ag – heat stable, common to all chlamydiae,
a lipopolysaccharide resembling LPS of GNB. Present in all stages.
2. Species specific protein Ags – present at the envelope surface, help in classifying chlamydia into species
3. Ag for Intraspecies typing – found only in some members of a species, located on major OMP (MOMP), demonstrated by micro- IF. Classifies species into serovars/ serotypes
24/02/2008 Dr Ekta, Microbiology, GMCA
Variants of Chlamydia
C. trachomatis – 2 biovars: TRIC & LGV1. TRIC – Trachoma, Inclusion conjunctivitis - divided into 12 serovars
2. LGV – Lymphogranuloma venereum – 3 serovars
24/02/2008 Dr Ekta, Microbiology, GMCA
Human diseasesSpecies Serotype Disease
C. trachomatis A, B, Ba, C Endemic blinding trachoma
C. trachomatis D to K Inclusion conjunctivitis. Genital chlamydiasis
C. trachomatis L1, L2, L3 Lymphogranuloma venereum
C. psittaci Many serotypes Psittacosis
C. pneumoniae Acute resp. disease
24/02/2008 Dr Ekta, Microbiology, GMCA
Laboratory Diagnosis
4 approaches available:1. Microscopic demonstration of inclusion or
elementary bodies2. Isolation of chlamydia3. Demonstration of chlamydial Ag4. Demonstration of Abs or hypersensitivity
24/02/2008 Dr Ekta, Microbiology, GMCA
Microscopy Gram negative but stained better by Giemsa, Castaneda or Machiavello stains.Giemsa Stain: Elementary body & the Reticulate body stains blue in cytoplasmLugol’s iodine: rapid & simple screening method for ocular infections, stains glycogen matrix of C. trachomatis
Immunoflurescence staining: more sensitive & specific, by using monoclonal Abs. Identifies inclusion bodies as well as extracellular elementary bodies. Used for ocular, cervical or urethral specimens.
24/02/2008 Dr Ekta, Microbiology, GMCA
IF staining
24/02/2008 Dr Ekta, Microbiology, GMCA
Culture
Yolk sac of 6 - 8 days old chick embryo.
Tissue culture – McCoy, HeLa cell lines
* C. psittaci carry the risk of laboratory infection.
24/02/2008 Dr Ekta, Microbiology, GMCA
Microscopic appearance
A monolayer of tissue culture cells has been exposed to cells of chlamydia trachomatis. Infected cells within the cell sheet have a cytoplasm with a granular appearance.
24/02/2008 Dr Ekta, Microbiology, GMCA
Demonstration of antigens
Micro – IF : infected ocular or genital samples are stained with fluorescent conjugated Ab
ELISA – best for screening large number of specimens, detects LPS Ag
Molecular methods - PCR
24/02/2008 Dr Ekta, Microbiology, GMCA
Chlamydia trachomatis
Leading cause of ocular & genital infectionsPathogenicities:
1. Trachoma2. Inclusion conjunctivitis3. Infant pneumonia4. Genital infections – genital chlamydiasis, LGV
24/02/2008 Dr Ekta, Microbiology, GMCA
Trachoma
Greek word trakkus – rough (roughness of conjunctiva)Caused by C. trachomatis types A, B & C.Chronic keratoconjunctivitisTransmitted by fingers, fomites, flies or dustEstablished trachoma passes through 4 stages (I – IV).Infectivity is maximum in early cases, stage IV is non infectious.
24/02/2008 Dr Ekta, Microbiology, GMCA
Laboratory diagnosis of Trachoma
Demonstration of characteristic inclusion bodies (Halberstaedter Prowazek or HP bodies) in conjunctival scrapings by Giemsa.
Culture – yolk sac, cell lines
24/02/2008 Dr Ekta, Microbiology, GMCA
Treatment & Control
Local application of antibioticsOral administration - Tetracycline or Doxycycline for several weeksSingle dose Azithromycin
Control – mass education & chemotherapy
24/02/2008 Dr Ekta, Microbiology, GMCA
Inclusion ConjunctivitisCaused by C. trachomatis types D to K
Naturally present in the genital tract
Neonatal form - “Inclusion Blenorrhoea”, develops when the infant is in birth canal, appears 5-12 days after birth, prevented by local application of antibiotics
Adult form – “Swimming Pool Conjunctivitis” – associated with bathing in community swimming pools contaminated with chlamydia from genital secretions.
24/02/2008 Dr Ekta, Microbiology, GMCA
Infant Pneumonia
Usually occurs around 4-16 wks of age.Cough & wheezing. Rarely feverConjunctivitis often precedes pneumonia
24/02/2008 Dr Ekta, Microbiology, GMCA
Genital Infections
Two types :1. Genital chlamydiasis2. Lymphogranuloma venereum
24/02/2008 Dr Ekta, Microbiology, GMCA
Genital chlamydiasisMost common STD, clinical spectrum similar to gonococcal infections.Men – urethritis (NGU), epididymitis, proctitis & Reiter’s syndromeWomen – acute urethral syndrome, mucopurulent cervicitis, endometritis, salpingitis, PID, infertility, ectopic pregnancy, premature delivery, postpartum fever.
Diagnosis – gram stained smears of urogenital exudates showing – more than 4 neutrophils / OIF in urethritis, – >30 / OIF in cervicitis.
Confirmatory tests – culture, micro-IF, ELISA, PCR
24/02/2008 Dr Ekta, Microbiology, GMCA
Lymphogranuloma venereum
Most commonly caused by L2 typeSite – regional lymph nodesIncubation period – 3 days to 5 wks1° lesion – small painless papulovesicular lesion on external genitalia2° stage – after 2 wks, lymphatic spread to draining LNs (men – inguinal, women – intrapelvic & pararectal)
24/02/2008 Dr Ekta, Microbiology, GMCA
Lymphogranuloma venereumNodes enlarge, suppurate, become adherent to the skin & break down to form discharging sinuses.
Metastatic complications – may occur, involves joints, eyes & meninges3° stage – chronic, lasts for several years; scarring & lymphatic blockageLate sequelae more distressing in women – rectal strictures, elephantiasis of vulva (esthiomene)
24/02/2008 Dr Ekta, Microbiology, GMCA
Laboratory Diagnosis of LGV
Demonstration of elementary bodies in materials aspirated from bubos (inguinal)Isolation – cell culturesSerology – detection of Abs
1. CFT 1: 64 or more2. Micro- IF 1: 512 or more
Frei Test – ID test using crude chlamydial Ag, not done now.
24/02/2008 Dr Ekta, Microbiology, GMCA
Chlamydia psittaci
Causes Psittacosis – disease of parrotsShed in the droppings or nasal discharges and aerosols are liberated.Humans – occupational disease as in poultry workers, pigeon farmers, petshop owners, veterinarians; laboratory acquired infection
Infection by inhalation.
Mild influenza like syndrome to fatal pneumonia
24/02/2008 Dr Ekta, Microbiology, GMCA
Laboratory Diagnosis
Specimen – blood (early stages), later sputumDemonstration of LCL (Levinthal-Cole-Lillie) Inclusion bodies in alveolar macrophages, mouse brain, yolk sac, cell cultures LCL bodies - more diffuse & irrregular, not stained by iodineSerology – CFT, micro-IF
24/02/2008 Dr Ekta, Microbiology, GMCA
Chlamydia pneumoniaeIsolated in 1986 from acute respiratory diseases in adults in Taiwan – C. psittaci strain TWARLater classified as a separate species.Common cause of respiratory disease in older children & adults.C/F – pharyngitis, sinusitis, bronchitis & pneumonia (atypical pneumonia)Outbreaks in closed communities.Reinfections are common.
24/02/2008 Dr Ekta, Microbiology, GMCA
Chlamydia pneumoniaeDiagnosis – Ag detection by EIA, direct IF, PCR, as isolation is very difficult.Treatment – clarithromycin or azithromycinNewer findings – suspected to be associated with atherosclerosis and its clinical effects like coronary, carotid & cerebral arterial disease.Evidences – detection of chlamydial Ags in plaques, isolation of chlamydia from coronary artery plaques, experimental induction of atheroma in rabbits infected with chlamydia
24/02/2008 Dr Ekta, Microbiology, GMCA
So…What’s Chlamydia anyways?
How is it detected, treated and prevented?
If it happens to me, what do I do?
What are the possible complications?
Chlamidia