1 / 21

Chlamydiacae

Chlamydiacae. The taxonomy of Chlamydiacae has been revised on the basis of genomic studies; and accordingly they have been divided into 2 genera: Chlamydia Chlamydophila Chlamydia trachomatis Chlamydia psittaci Chlamydia pneumoniae 2 biovars

maylin
Télécharger la présentation

Chlamydiacae

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chlamydiacae • The taxonomy of Chlamydiacae has been revised on the basis of genomic studies; and accordingly they have been divided into 2 genera: ChlamydiaChlamydophila Chlamydia trachomatis Chlamydia psittaci Chlamydia pneumoniae 2 biovars Trachomatis & LGV

  2. They were once considered as viruses because : They are small enough to pass through o.45µ filters They are obligate intracellular parasites. • They are now considered asbacteriabecause: 1.They have inner & outer membranes similar to gram negative bacteria. 2. They contain both DNA &RNA 3.They can synthesize their own proteins, nucleic acids & lipids 4.They are susceptible to many antibiotics.

  3. Antigenic structure 1. They have a genus-specific lipopolysaccharide detected by complement fixation test. 2. They have species &strains-specific outer membrane proteins • Staining 1. Giemsa………….stains the elementary bodies , the reticulate bodies &inclusions (not for definitive diagnosis ) 2. Gram……………gram negative or gram variable (difficult ) 3. Immunofluorescense 4. Iodine……………for intracellular inclusions which contain glycogen

  4. Developmental cycle of Chlamydia • -EB (elementary body )attaches to the surface of susceptible cell & enters the cell by phagocytosis -The elementary body organizes into RB ( Reticulate body ). -The reticulate body divides by binary fission. -After 24-48 hrs ,EBs are released and initiate a new cycle of infection -The mass of EBs → Inclusion body→detected by histologic stains NB 1-After internalization,bacteria remain within the cytoplamic phagosome & replicate. 2-Fusion of cellular lysosomes & EBs containing phagosome , and subsequent intracellular killing is inhibited (bacteria not affected by lysosymes • NB 1-After internalization,bacteria remain within the cytoplamic phagosome & replicate. 2-Fusion of cellular lysosomes & EBs containing phagosome , and subsequent intracellular killing is inhibited (bacteria not affected by lysosymes

  5. Growth • Eukaryotic cell lines : Hela cells-229 , Mc Coy cells , BHK -21 , Buffalo green monkey kidney cells. • Sensitivity is increased by pretreatment with cycloheximide (to decrease host metabolism ), use of shell vial technique ( growth of host cell monolayer on glass cover slips rather than in small microtiter plates), use of Iodine stain or Fluorescein-conjugated antibodies to detect intracellular inclusions. - Embryonated egg yolk sac. - Mice (rarely used ) Reaction to physical & chemical agents • Heat …………….at 60°C,for 10 min leads to their inactivation • Ether……………..for 30 min………..leads to rapid inactivation • Phenol 0.5%, for 24h…………………leads to inactivation • Freeze drying…………………………decreases their infectivity • Dryness……………………………….does not affect infectivity

  6. Treatment - Both sex-parteners should be simultaneously treated - Tetracyclins are commonly used in non-gonococcal urethritis and in non-pregnant females. - Azithromycin is also effective. - Erythromycin may be an alternative in pregnant females - Topical Tetracyclin or Erythromycin………for inclusion conjunctivitis. - In LGV……….Sulfonamides & Tetracyclins for the early stages;but late stages require surgery.

  7. Chlamydia Trachomatis • It has a very limited range of infection (infects humans only) • It has 2 Biovars: Trachoma (15 serovars A,B,Ba,C,D-K ) LGV (4 serovars L1,L2,L2a,L3)

  8. Clinicalsyndromes 1. Infections in Adults • Non-gonococcal urethritis (NGU) in males - 50% of cases of NGU are sexually acquired. - 25% are asymptomatic but are able to transmit the organism. - When symptoms occur (urethral discharge,difficult micturition),they are mild (unlike gonococcal urethritis).Serious complications are rare. • Mucopurulent cervicitis in females - It is the female counterpart of male NGU - It is acquired through sexual intercourse.Many remain asymptomatic. - The Gram stain of the endocervical swab shows yellow-green mucous and more than 10 PNLs/ HPF.(Neisseria must be excluded) - Complications include PID

  9. Pelvic inflammatory disease (PID) - It is an ascending infection. - Although symptoms may be mild yet laparoscopy may show severe inflammation. - Complications include salpingitis, endometritis,peritonitis, Prihepatitis(Fitz-Hugh Curtis syndrome).These may lead to infertility,chronic pelviabdominal pain & ectopic pregnancy. • Lymphogranuloma venereum - It is a sexually transmitted disease. - The IP is about 4w. - The primary lesion occurs at the site of infection:vesicle,papule or ulcer,small,painless heals rapidly so it might be overlooked. - The second stage which occurs after2-5w shows marked inflammation& swelling of the lymph nodes (usually inguinal) - There is constitutional symptoms (usually severe).Fistulae may form (especially after needle aspiration)

  10. Acute urethral syndrome Occurs in young women in the form of recurrent dysuria,pyuria& sterile culture • Ocular infections 1- Trachoma :( A,B,Ba,C ) keratoconjunctivitis,invasion of blood vessels into the cornea,bacterial infection&scarring. 2- Inclusion conjunctivitis :( A,B,Ba,D-K) in sexually active adults. It may occur as an autoinfection. • Proctocolitis &epididymitis • Reiter' s syndrome: conjunctivitis,reactive arthritis and urethritis.

  11. 2. Infections in infants • Newborns………..from infected birth canal • Infants pneumonia (1-6 mo ) : usually associated with conjunctivitis. • Infants conjunctivitis :It is the commonest cause of neonatal conjunctivitis& is associated with mucopurulent discharge(2-3w after birth).Most cases resolve without sequelae. However,some may develop chronic ocular infection

  12. Diagnosis 1. Culture 2. Non-cultural methods: - Cytology : cell scrapings for inclusions,but is insensitive compared to culture &immunofluorescence. - Antigen detection: by direct immunofluorescence, ELISA(less sensitive than culture) - Nucleic acid probes: test the presence of a specific species-specific sequence of 16S rRNA.It is rapid & relatively inexpensive. - PCR,LCR,TMA (transcription mediated amplification), SDA (standard displacement ).They have a sensitivity of 90-98% In the very near future,they will be the test of choice. - Serology: has a limited value in Chlamydia trachomatis causing genital infections in adults,because antibody titers persist for a long period so,do not differentiate between concurrent and past infections; although a significant rise in antibody titer is useful.

  13. Chlamydia Psittaci • Causes Psittachosis, Ornithosis, Parrot fever • Humans are infected by contact with birds, inhalation of dried bird excrement, urine or resp. secretions. • IP 4d • C/ P: From mild inapparent or flu like inf. to severe pneumonia with sepsis and high mortality rate (20%) now decreased to 2%. • Path: RT Blood Liver, Spleen, Kidneys and lungs.

  14. Diagnosis 1) Serology: 4 fold rise by CFT  confirm by MIF Sometimes specific IgM Antibody can be demonstrated. 2) Cell culture: rarely performed Treatment Te, Macrolides

  15. Chlamydia Pneumoniae • Was 1st isolated from conj. of a child in Taiwan (TW-183) and was found to be related to a pharyngeal isolate (AR-39)  TWAR  C. pneumoniae  Chlamyolophila ( only a single serotype) • Transmitted by resp. secretions (person to person) • Human pathogen • Common in adults

  16. Clinical Picture • Usually mild or asymptomatic • May cause bronchitis, pneumonia, sinusitis • Cannot be diff. from other atypical pneumonias (Mycopl, Legionella,….) • Associated with atherosclerosis Diagnosisdifficult • Do not grow • Amplification techniques √ • Serology: • Complement Fixation: not specific (positive for both Chlamydia and Chlamydophia) • IF √√ : the most sensitive and specific. It uses EBs as antigens Treatment • E, Te, Lev 10-14d

  17. Characteristics of the Chlamydiae

More Related