Chlamydiae

Chlamydiae Chlamydiae are small gram-negative bacteria which obligate intracellular parasites and multiply in the cytoplasm of their host cell by a distinctive developmental cycle.

Classification 1. chlamydia trachomatis 2. chlamydia psittaci on the basis of antigen composition, intracellular inclusion, sulfonamide susceptibility and disease production,they are divided into 4 species: 1.  chlamydia trachomatis 2.  chlamydia psittaci 3.  chlamydia pneumeniae 4.  chlamydia pecorum

Classification C. trachomatis can be divided into three biovars: (1)  Biovar trachoma Serovars(serotype): A, B, Ba, C,D,Da,E,F, G,H,I,Ia,J,and K 14 serotype. A,B,Ba and C---trachoma D～K---sexnaly transmitted infection (2)  Biovar lymphogranuloma venereum (LGV) L1,L2,L2a and L3---LGV (3)  Biovar mouse

Characteristics 1. It differs from virus (1) They possess both RNA and DNA (2)  Binary fission (3) They have a rigid cell wall that resembles a bacterial type cell wall(G-). It does not have typical peptidoglycan layer and lacks muramic acid.

Characteristics (4) Ribosome (5)  They have a variety of metabolically active enzymes, eg .they can librate CO2 from glucose. Some can synthesize folates. (6) Their growth can inhibited by many antimicrobial drugs, especially tetracycline and erythromycins.

Characteristics 2. development cycle Two particles were found in infected cell. (1)  Elementary body (EB): infectious particles, small (0.3µm in diameter),with an electron-dense nucleoid. A high affinity for host epithelial cells.

Characteristics

Characteristics (2) Initial body(IB): 0.5～1 µm, binary(reticulate body) fission→small particles (inclusion bodies)→ librated→other cell. The developmental cycle takes 24-48 hrs.

Characteristics 3. antigens (1) genus specific antigen: It is shared by all chlamydiae. Heat-stable lipopolysaccharide with 2-keto-3-deoxyoctonic acid. CF and immunofluorescence

Characteristics (2) species-specific antigen. Major outer membrane protein(MOMP) Immunofluorescence (3)  Immunotype-specific antigen MOMP McAb

pathogenicity 1. pathogenic substances endotoxin-like substance MOMP 2. clinical finding (1) trachoma It is a chronic keratoconjunctivits that begins with acute inflammatory changes in the conjunctiva and cornea and rogresses to scarring and blindness.

pathogenicity Immunotypes: A,B,Ba,C Transmission: eye→eye, eye→hand→eye. C.trachomatis→eye→3～10 day→earliest symptoms: lacrimation, mucopurulent discharge, conjunctival hyperemia, follicular hypertrophy→conjunctiva scar→trichiasis→ eyelashe sweeping corna→blindness.

pathogenicity (2) Genital chlamydial infections Immunotypes: D-K Transmission: sexual contact It is a promiment cause of nongonococcal urethritis, epididymitis (in male),urethritis, cervicitis,salpingitis and pelvic inflammatory (in female), Up to 50% of nongonococcal or postgonococcal urethritis or the urethral syndrome is attributed to chlamydiae and produces dysuria,nonpurulent discharge.

pathogenicity Inclusion conjunctivitis: Immunotype: B,Ba,D,Da,E,F,G,H,I,Ia,J and K Newborn---infected birth canal Adults---sexual contact Inclusion conjunctivitis in adults results from self-inoculation of genital secretion.

pathogenicity (3) Lymphogranulom venereum(LGV) LGV is a sexually transmitted disease characterized by suppurative inguinal adenitis. L1-L3

pathogenicity (4) psittacosis psittacosis is a disease of birds that may be transferred to humans. In human,the agent, C. psittaci, produces a spectrum of clinical manifestations ranging from severe pneumonia and sepsis with a high mortality rate to a mild inapparent infection.

pathogenicity (5) C. Pneumoniae (TWAR) TW-138 AR-39 Human to human Respiratory infection→pnenmoniae TWAR

Laboratory liagnosis 1. cytolcgy 2. cuture 3. serology ELISA 4. Nucleic acid probes: PCR, ligase chain reaction(LCR)