1. CHLAMYDIA
II MBBS
24/02/2008 Dr Ekta, Microbiology, GMCA

2. KEY WORDS
Intracellular Inclusion conjunctivitis
Energy parasites Lymphogranuloma venereum
Elementary body Frei test
Reticulate body Genital chlamydiasis
Inclusion bodies – HP, LCL C. psittaci
Biotypes/ serotypes Psittacosis
Tissue culture Ornithosis
C. trachomatis C. pneumoniae
Trachoma
24/02/2008 Dr Ekta, Microbiology, GMCA

3. INTRODUCTION
Obligate 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

4. 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

5. Classification
C.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

6. Life cycle
Chlamydiae occur in 2 forms :
1. Elementary body – extracellular, infective form
2. 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

7. 24/02/2008 Dr Ekta, Microbiology, GMCA

8. 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

9. Antigenic Properties
Three major Ags
1. 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

10. Variants of Chlamydia
C. trachomatis – 2 biovars: TRIC & LGV
1. TRIC – Trachoma, Inclusion conjunctivitis
- divided into 12 serovars
2. LGV – Lymphogranuloma venereum – 3
serovars
24/02/2008 Dr Ekta, Microbiology, GMCA

11. Human diseases
Species 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

12. Laboratory Diagnosis
4 approaches available:
1. Microscopic demonstration of inclusion or
elementary bodies
2. Isolation of chlamydia
3. Demonstration of chlamydial Ag
4. Demonstration of Abs or hypersensitivity
24/02/2008 Dr Ekta, Microbiology, GMCA

13. Microscopy
Gram negative but stained better by Giemsa, Castaneda
or Machiavello stains.
Giemsa Stain: Elementary body & the Reticulate body
stains blue in cytoplasm
Lugol’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

14. IF staining
24/02/2008 Dr Ekta, Microbiology, GMCA

15. 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

16. 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

17. 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

18. Chlamydia trachomatis
Leading cause of ocular & genital infections
Pathogenicities:
1. Trachoma
2. Inclusion conjunctivitis
3. Infant pneumonia
4. Genital infections – genital chlamydiasis, LGV
24/02/2008 Dr Ekta, Microbiology, GMCA

19. Trachoma
Greek word trakkus – rough (roughness of
conjunctiva)
Caused by C. trachomatis types A, B & C.
Chronic keratoconjunctivitis
Transmitted by fingers, fomites, flies or dust
Established 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

20. 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

21. Treatment & Control
Local application of antibiotics
Oral administration - Tetracycline or
Doxycycline for several weeks
Single dose Azithromycin
Control – mass education & chemotherapy
24/02/2008 Dr Ekta, Microbiology, GMCA

22. Inclusion Conjunctivitis
Caused 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

23. Infant Pneumonia
Usually occurs around 4-16 wks of age.
Cough & wheezing. Rarely fever
Conjunctivitis often precedes pneumonia
24/02/2008 Dr Ekta, Microbiology, GMCA

24. Genital Infections
Two types :
1. Genital chlamydiasis
2. Lymphogranuloma venereum
24/02/2008 Dr Ekta, Microbiology, GMCA

25. Genital chlamydiasis
Most common STD, clinical spectrum similar to gonococcal
infections.
Men – urethritis (NGU), epididymitis, proctitis & Reiter’s syndrome
Women – 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

26. Lymphogranuloma venereum
Most commonly caused by L2 type
Site – regional lymph nodes
Incubation period – 3 days to 5 wks
1° lesion – small painless papulovesicular lesion
on external genitalia
2° stage – after 2 wks, lymphatic spread to
draining LNs (men – inguinal, women – intrapelvic
& pararectal)
24/02/2008 Dr Ekta, Microbiology, GMCA

27. Lymphogranuloma venereum
Nodes enlarge, suppurate, become adherent to
the skin & break down to form discharging
sinuses.
Metastatic complications – may occur, involves
joints, eyes & meninges
3° stage – chronic, lasts for several years;
scarring & lymphatic blockage
Late sequelae more distressing in women – rectal
strictures, elephantiasis of vulva (esthiomene)
24/02/2008 Dr Ekta, Microbiology, GMCA

28. Laboratory Diagnosis of LGV
Demonstration of elementary bodies in
materials aspirated from bubos (inguinal)
Isolation – cell cultures
Serology – detection of Abs
1. CFT 1: 64 or more
2. Micro- IF 1: 512 or more
Frei Test – ID test using crude chlamydial Ag,
not done now.
24/02/2008 Dr Ekta, Microbiology, GMCA

29. Chlamydia psittaci
Causes Psittacosis – disease of parrots
Shed 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

30. Laboratory Diagnosis
Specimen – blood (early stages), later sputum
Demonstration of LCL (Levinthal-Cole-Lillie)
Inclusion bodies in alveolar macrophages,
mouse brain, yolk sac, cell cultures
LCL bodies - more diffuse & irrregular, not
stained by iodine
Serology – CFT, micro-IF
24/02/2008 Dr Ekta, Microbiology, GMCA

31. Chlamydia pneumoniae
Isolated in 1986 from acute respiratory diseases
in adults in Taiwan – C. psittaci strain TWAR
Later 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

32. Chlamydia pneumoniae
Diagnosis – Ag detection by EIA, direct IF, PCR,
as isolation is very difficult.
Treatment – clarithromycin or azithromycin
Newer 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

33. 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
24/02/2008 Dr Ekta, Microbiology, GMCA