Uploaded byDr. Rakesh Prasad Sah
Chlamydia
Chlamydia is an obligate intracellular parasite that can cause various diseases in humans. It exists in two forms - the elementary body, which is the infectious form, and the reticulate body, which is the replicative form inside host cells. Chlamydia trachomatis is the most common species and has multiple serotypes that can cause trachoma, genital infections, or lymphogranuloma venereum. Diagnosis involves direct detection of the organism by microscopy or antigen tests, isolation in cell culture, and serological detection of antibodies.
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Chlamydia
- 1. Chlamydia By Dr. RakeshPrasad Sah Associate Professor, Microbiology
- 2. Introduction • Obligate intracellularparasites – Small – Gram-negative – Non-motile • Causes – Trachoma – Lymphogranuloma venerum (LGV) – Psittacosis in man – Were called “psittacosis-lymphogranuloma-trachoma (PLT)” or “TRIC (trachoma-inclusion conjunctivitis) organisms”.
- 3. • Name Chlamydia derived from characteristic appearance of inclusion body of these agents. The inclusion bodies enclose the nuclei of infected cells as a cloak or mantle. (Chlamys mantle) • D/t- filterability (0.45μm) & failure to grow in cell free media- were once considered – viruses. • Not able to form own – ATP, lack enzymes of e transport chain - depend on host cells – called Energy parasites.
- 4. Differences between Chlamydia& Viruses • As - obligate intracellular parasites / filterability / no growth in cell free media - previously thought to be viruses Differ from viruses - following properties 1) Possess both DNA & RNA - Like bacteria 2) Have rigid cell walls/ prokaryotic ribosomes similar to bacteria 3) Multiply by binary fission 4) Susceptible – Antibiotics / chemotherapeutic agents – so accepted as BACTERIA • But like Bacteria – do not have PG cell walls, lack enzymes of electron transport chain , no ATP synthesis
- 5. Chlamydiae Classification • Family Chlamydiaceae previously contained a single genus Chlamydia. Chlamydiaceae Chlamydia Chlamydia trachomatis Chlamydophila Chlamydia psittaci Chlamydia pneumoniae
- 6. Chlamydia trachomatis • C.trachomatis strain classified into 20 serotypes A, B, Ba, C, D, Da, E, F, G, H, I, Ia, J, Ja, K, L1, L2, L2a, L2b and L3. S. No. Serotype Disease 1 A, B, Ba, C Trachoma 2 D, Da, E, F, G, H, I, Ia, J, Ja, K Inclusion conjunctivitis, non-gonoccal urethritis, salpingitis, cervicitis, epididymitis, proctitis and pneumoniae of infants. 3 L1, L2, L2a, L2b, L3 Lymphogranuloma venereum (LGV)
- 7. Chlamydophila pneumoniae • Formerly “TWAR strain” • Causes – Community acquired atypical pneumoniae – atherosclerosis S.No Species Serotype Disease 1 C. Psittaci Many serotypes Psittacosis (atypical interstitial pneumonia) 2 C. Trachomatis A, B, Ba, C Trachoma 3 C. Trachomatis D, Da, E, F, G, H, I, Ia, J, Ja, K •Inclusion conjunctivitis •Genital chlamydiasis •Infant pneumonia 4 C. Trachomatis L1, L2, L2a, L2b, L3 Lymphogranuloma venereum 5 C. Pneumoniae One serotype •Community acquired atypical pneumoniae •Associated with atherosclerosis
- 8. Morphology and DevelopmentCycle • Exist in 2 forms – – ELEMENTRY BODY ( EB) & RETICULATE BODY ( INITIAL ) 1) EB – – spherical particle - 200 – 300 nm in diameter – Extracellular infective form – metabolically inert 2) RB – Non infectious in nature. – Intracellular growing & replicative form. – 500 – 1000 nm in size, – metabolically active
- 9. • Chlamydia –EB/ IB – large enough to be seen – L. microscope • Chlamydia is GM –ve , other better stains – Castaneda – Machiavello – Giemsa • C. trachomatis stained by – Lugol’s iodine – glycogen matrix
- 10. Host Cell Phagocytosis Elementary body Release ofElementary Bodies Reticulate body
- 11. Cycle of development Attachment-to surface of susceptible Epithelial cell Enters the host cell by phagocytosis/ endocytosis – Once internalized remain in phagosome –Prevent phagosome Lysosome fusion Enlarges / under go reorganization - Reticulate body ( RB ) - 500 – 1000 nm in size Some RB become EB Liberated from host cell by cell lysis Divides rapidly by B. F. -- To produce large no of RB ( newly formed infectious particles within host cell - IB ) Mature IB -100 -500 RB . Duration is 24-48hrs
- 14. Ag Structure 1) Genussp Ags • Heat stable - common to all chlamydiae. • LPS in nature. • Similar to LPS of GNB. • Present in all stages of the developmental cycle. • Identified by CFT. 2) Species specific protein Ags • at envelope surface- • Help in classifying chlamydiae in to different species 3) Serotype specific Ags • Helps in intraspecies typing • Ex- C. trachomatis – 15 serotypes A- K & L1 – L3 • located on MOMP(Major outer membrane protein)- can be demonstrated by – micro IF
- 15. RESISTANCE • Heat labile– inactivated with in minutes at 56oc • Susceptible to ethanol, ether , phenol & formalin • Infectivity is maintained for several days at 4oc • Can be preserved frozen at – 70oc or lyophilised.
- 16. CULTURE --Chlamydia canbe isolated by 1. Animal inoculation – mice 2. Yolk sac inoculation – Embryonated egg 3. Tissue culture
- 17. Animal inoculation Mice ELEMENTARY bodies Inoculatedby intranasal, intraperitoneal , intracerebral Die 10 days smears - various tissues – lung, spleen, brain, peritoneal exudate
- 19. Yolk Sac Inoculation •OF 6-8day old chick embryos Group sp. CF Ag / EB & IB -Organisms detected in impression smears –stained by Giemsa, Gimenez method Tedious / insensitive
- 20. Embryonated Hen’s Egg AMNIOTICSAC..--------------------- YOLK SAC AIR SAC EYE EGG SHELL CHORIOALLONTOIC MEMB------ ------- ALLANTOIC CAVITY
- 21. Tissue Culture • Preferredmode • commonly used cell lines- – McCoy cells pretreated by irradiation or with cycloheximide – HeLa – Monkey kidney cells . • Organisms in tissue culture - detected by staining for inclusion or elementary bodies
- 22. Pathogenesis • Occurs inthree forms – Ocular infections – Genital infections – Respiratory infections
- 23. Trachoma • Chronic keratoconjunctivitis formation of conjunctival follicles enlarges/ hypertrophy Necrosis of it Scarring Blindness • Trachoma- Greek trakhus – rough – roughness of conjunctiva in the disease • Is a chronic keratoconjunctivitis major cause of blindness. • Characterized by – Follicles – Paplliray hyperplasia – Annus formation – In the late stage cicatrization.
- 24. • C. trachomatisserotypes A, B, Ba &C causative agents • MOT – by fingers, towels , clothing, flies. • I.P. 3-10 days • Children below – 9 yrs frequently affected Trachoma – classified – four stages I- IV. • Infectivity maximum – early stages
- 25. Inclusion Conjunctivitis • Causedby C. trachomatis serotypes D – K. • Natural habitat – genital tract • Most prevalent in sexually active young people • Spread from – genital secretions to the eye – hand inf. Contact. • Also obtain from contaminated swimming pools so formerly “Swimming pool conjunctivitis”also known as “Paratrachoma”.
- 26. Ophthalmia neonatorum/Neonatal Conjunctivitis •Neonatal form of inclusion conjunctivitis. • Infant acquires infection – passage through infected birth canal of mother. • Infection becomes apparent between 5 – 12 days after birth. • 20- 50 % infants of infected mothers develop infection
- 27. Genital Infections Genital Chlamydiasis •C. trachomatis – serotypes D to K – responsible for 40% NGU (Non- gonococcal urethritis). • STD • In addition to urethritis, it may cause – Epididymitis – Proctitis • In Females – Urethritis – Cervicitis – Salpingitis – Pelvic inflammatory disease (PID) Infection Asymptomatic Symptomatic •Dysuria •Non-purulent discharge •Frequency of urination
- 28. Lymphogranuloma Venereum • STD– Caused by C.trachomatis serotypes L1 – L3. • small painless papule / vesicle external genitalia ulcerate heal. • Regional lymph nodes (m- inguinal & f- intrapelvic, pararectal) enlarged , tender , adherent to the skin break open with formation of sinuses - discharging pus. • Enlarged inguinal LN – called “Buboes”.
- 30. • Complication – –Perianal abscesses – fistula • Late sequelae - rectal strictures, elephantiasis of vulva • Metastatic complications- involvement of joints , eyes, meninges.
- 31. Respiratory Infections Chlamydia Pneumonia •C. pneumoniae – Also called “TWAR” - Taiwan Acute Respiratory agent. • 3rd most commom cause of pneumonia following Str. Pneumoniae & H. Influenzae in older children /Adults. • Exclusively human pathogen - transmitted from H to H without any avian / animal host. • C. pneumoniae- disseminate systemically after respiratory inf– induces/enhances development of Atherosclerosis- coronary, carotid, cerebral arterial diseases.
- 32. Psittacosis • Is adisease of Parrots / other psittacine birds. • Non psittacine birds- Ornithosis • In birds – subclinical inf / carrier shed in droppings , nasal discharge. • Human infection – inhalation of dried faeces / rarely bite. • Disease - vary from a mild influenza like syndrome to severe illness with – Pneumonia – Septicemia – Meningoencephalitis.
- 33. Lab Diagnosis Consist of 1)Direct detection of Ags – Microscopic demonstration of IB / EB 2) Isolation 3) Serology for Ab detection 4) Skin test Sample collection • Ocular , urethral , vaginal , cervical – by scraping the mucosa. • Additionally Blood , sputum , respiratory secretions . In LGV - pus / discharge - bubo
- 34. Direct Detection OfAgs By light microscopy • infection of conjunctiva, urethra & cx – by C. trachomatis - diagnosed by demonstration of inclusion bodies – smear stained – Giemsa / Castanaeda / Machiavello.
- 35. Direct Detection OfAgs • I. B. – Trachoma / inclusion conjunctivitis TRIC – Halberstaedter Prowazek or HP bodies where as E.B. C. psittacia – called Levinthal Cole Lillie or LCL bodies.
- 36. Direct Detection OfAgs • I.B. – C. trachomatis - contain glycogen matrix - stained with Iodine solution, poor sensitivity - useful – rapid screening for chlamydial Inclusions in cell cultures
- 37. HP BODY –conjunctivalepithelial cell with large reniform I. B. , surrounding the nucleus
- 39. Immunofluorescence • More sensitive& specific • Rapid test . Smear stained - fluorescent labeled monoclonal Abs – for detection of both – I. B. /extracellular E. B. – more S than Iodine staining for detection of I.B.- in cell cultures • Besides ocular infs- useful in examination of cervical & urethral specimens contain E. B. & few intact intracellular inclusions
- 40. • ELISA – –detects soluble genus - specific Ags . – Useful in C. pneumoniae inf - as isolation very difficult • DNA probes – for detection of DNA of C.ntrachomatis in conjunctival & cervical smears –specific probes used • PCR – DNA- amplified – detected • Chemiluminescence- Acridium ester labeled DNA probe – complementary to RNA of C. trachomatis used – by measuring light emitted results given
- 41. Isolation • Isolated byinoculation in to • Mice - no longer in use • Yolk sac of chick embryo – Tedious / insensitive • Tissue cultures – better method Serology For Ab Detection • BY CFT – in psittacosis & LGV – 4 fold rise significant little value – in TRIC inf • By Microimmunofluorescence – C. trachomatis & C. pneumoniae. • By ELISA- IgM detection diagnostic – in neonatal chlamydial pneumonia. Skin Test – Frei’s test – LGV Ag – nodule 7mm in dia