Chlamydiacae

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

5. 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

7. 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

8. 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.

9. 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)

10. 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

11. 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)

12. 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.

13. 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

14. 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.

17. 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.

18. 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

19. 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

20. 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

21. Characteristics of the Chlamydiae