1. Mycoplasma & Chlamydia

2. Mycoplasmas (Mycoplasmas spp) Mycoplasmas are groups of small, wall-less organisms. They are the smallest free-living organisms (0.3μm in diameter).

3. Important properties: 1) Mycoplasmas stain poorly with Gram stain
Important properties: 1) Mycoplasmas stain poorly with Gram stain. 2) The outer surface is a flexible three layer cell membrane; hence the organisms can assume a variety of shapes. 3) It contain cholesterol in their bacterial membrane. 4) The colony frequently has a characteristic (fried egg) shape, with a raised center & a thinner outer edge.

4. In human there are four important species: 1) Mycoplasma pneumoniae
In human there are four important species: 1) Mycoplasma pneumoniae 2) M. Hominis 3) M. Genitalium 4) Ureaplasma urealyticum

5. Pathogenesis: Pathogenic Mycoplasmas have flask-like or filamentous shapes & have specialized polar tip structures that mediate the adherence to host cells (ciliated & non ciliated cells).

6. 1) M. pneumoniae •Is transmitted from person to person by means of infected respiratory secretions & cause atypical pneumonia. May be ranged from asymptomatic infection to serious pneumonitis. Incubation period 1-3 weeks.

7. • Symptoms: Fever, headache, sore throat, & cough which is non-productive .Complications are uncommon, but sometimes hemolytic anemia, meningitis & pericarditis may occur

8. • Diagnosis:  Culture: haert infusion peptone broth (with 2% agar & 30% human ascitic fluid or animal serum, pH 7.8).  Complement fixation (cf test).  Cold hemagglutination (at 4C°).  ELISA. • Treatment: Tetracycline & erythromycin.

9. 2) Mycoplasma hominis: causes infections of uterine tubes (salpingitis) & tubo-ovarian abscesses (in Women). 3) Mycoplasma genitalium: Associated with some infections of chronic nongonococcal urethritis (in men).

10. 4)Ureaplasma urealiticum: causes nongonococcal urethritis in some men (may play role in male infertility). Lung diseases in premature low birth-weight infants (acquired during birth

11. Chlamydiae (Chlamydia spp
Chlamydiae (Chlamydia spp.) • Chlamydiae: are obligate intracellular bacteria, lack the ability to produce sufficient energy to grow independently & therefore can grow only inside host cell. Chlamydiae have a replicative cycle different from that of all other bacteria. Within cells site of replication appears as an inclusion body, which can be stained & visualized microscopically. These inclusions are useful in the identification of these organisms in the clinical laboratory. •They have rigid cell wall but they don’t have typical peptidoglycan. Their cell walls resemble those of G- negative but lack muramic acid.

12. Chlamydia spp., inclusion bodies within host cells

13. Pathogenesis: Chlamydiae infect primarily epithelial cells of the mucous membrane and the lungs. Diseases: 1)Chlamydia psittaci: infects the lungs →human psittacosis, this disease may be asymptomatic or produce high fever & pneumonia. 2) C. pneumoniae →upper & lower respiratory tract infections especially bronchitis & pneumonia. 3) C. trachomitis types A, B&C →trachoma (chronic conjunctivitis endemic in Africa & Asia).

14. 4) C. trachomatis types D-K →genital tract infections, which occasionally transmitted to the eyes or the respiratory tract. • In men: it common cause of non-gonococcal urethritis, which may progress to epididymitis, prostatitis or proctitis • In women: cervictitis develops & may progress to salpingitis & pelvic inflammatory disease →this may result infertility or ectopic pregnancy. • Infants borne to infected mothers often develop mucopurulent eye infections (neonatal inclusion conjunctivitis) 7-12 days after delivery. Some develop chlamydial pneumonitis 2-12 weeks after birth. • 5) C. trachomitis L1-L3 immunotypes →lymphogranuloma venereum ,a sexually transmitted disease with lesions on genitalian & in lymph nodes .

15. Diagnosis: • Group-specific Ag
Diagnosis: • Group-specific Ag. (lipopolysaccharide) → complement fixation test. • Species-specific & immunotype-specific Ag. (Protein)→ Immunofluorescence test . • Chlamydiae form cytoplasmic inclusions →stain with Giemsa →immunofluorescence test . Treatment: Tetracyclines such as doxycycline & macrolides,such as erythromycin & azithromycin .