Chapter 46 Chlamydiaceae ( 披衣菌 / 衣源體 )

1. Microbiology 2011 May 16, 2011 Yu Chun-Keung Chapter 46Chlamydiaceae(披衣菌/衣源體) Chapter 44Rickettsia and Orientia (立克氏體)Chapter 45Ehrlichia, Anaplasma, Coxiella

2. Chapter 46 Chlamydiaceae • Obligate intracellular organisms • Were once considered virus, true bacteria • Contain DNA and RNA • Possess ribosomes, synthesize proteins, nucleic acid, and lipids, but cannot synthesize ATP. • Binary fission • Susceptible to numerous antibiotics, but not to penicillin (lack peptidoglycan) • Cell wall: • Genus-specific LSP • Major outer membrane protein (MOMP) – species specific antigens, serological variants (serovars)

3. Unique development cycle Two morphological distinct forms in cytoplasmic phagosome: (1) elementary body (300-400 nm), resistant to harsh environmental factors; infectious, bind to receptors of host cells and stimulate uptake; cannot replicate (2) reticulate body (800-1000 nm), reproductive form, metabolically active, noninfectious. Histologic stains can detect phagosome with accumulated RBs (inclusion)

4. Family Chlamydiaceae Genus Chlamydia: C. trachomatis(砂眼披衣菌) Genus Chlamydophilia: C. pneumoniae(肺炎披衣菌)C. psittaci(鸚鵡熱披衣菌)

5. 1. Chlamydia trachomatis (砂眼披衣菌) • Infections only occur in humans • Two biovarsand 18 serovars (antigenic differences in MOMP) Biovars Serovars Disease caused Trachoma A to C Trachoma D to K Urethritis, cervicitis, Inclusion conjunctivitis, Neonatal conjunctivitis, Infant pneumonia LGV L1 to L3 Lymphogranuloma venereum

6. Pathogenesis • EBs enter the body via minute abrasions and lacerations • Trachoma serovars primarily infect nonciliatedepithelial cells (urethra, endocervix, endometrium, fallopian tube, anorectum, respiratory tract, conjunctiva) • LGV serovars replicate in mononuclear phagocytes(more invasive); formation of granuloma in lymph nodes draining the site of primary infection, abscesses, or sinus tracts formation

7. Pathogenesis • Direct destruction of cells during replication • Proinflammatory cytokine response stimulates a severe inflammation (accumulations of neutrophils, lymphocytes and plasma cells). • No long-lasting immunity after infection • Re-infection induces a vigorous inflammatory response with subsequent tissue damage (blindness and sterility).

8. (1) Trachoma (砂眼) • A chronic keratoconjuctivitis caused by serovars A, B, Ba, C. • Diffuse follicular conjunctivitis → eyelid inward → eyelashes abrade cornea → corneal ulceration →pannus formation (invasion of vessels into the cornea) →blindness • Endemic in the Middle East, North Africa, and southern Asia (crowded and poor sanitation regions); predominantly in children. Leading global causes of preventable blindness (>150 million infected, 6 million blinded). • Transmission: eye-to-eye by droplet, hands, contaminated clothing, flies.

10. Epidemiology • Worldwide; in USA bacterial STD: Chlamydia > Neisseriagonorrhoeae> Syphilis • Extremely sensitive to drying or disinfectants, cannot be spread through contact with inanimate objects • Not highly contagious, 30% change of infection after a single sexual contact • Can be acquired congenitally or by transfusion; bacteremia can persist for > 8 years • Incidence of late syphilis has markedly decreased, primary and secondary syphilis remain high

11. (2) Urogenital infections • Venereal infections caused by serovars of D to K. • The most common sexually transmitted bacterial disease in U.S. 2.8 million new cases annually (50 million worldwide). • In women: 80% asymptomatic as reservoir; bartholinitis, cervicitis, endometritis, salpingitis, urethritis, which can lead to sterility and ectopic pregnancy. • In men: 25% asymptomatic; nongonococcal urethritis (NGU; urethritis caused by pathogens other than gonococcus)

12. Nongonococcal Gonorrhea urethritis 1. Mild 1. Severe 2. Slow and prolonged 2. Acute 3. Dysuria is mild 3. Severe dysuria 4. Urethral discharge is 4. Purulent clear or white, thin discharge and mucoid

13. Nongonococcal Urethritis (NGU) • C. trachomatis (35-50% of cases) • Ureaplasma urealyticum(10-30% of cases) • Mycoplasma hominis • Gardnerella vaginalis • Trichomonas vaginalis • Candida albicans

14. Post-gonococcus urethritis • Dual infections of C. trachomatis and Neisseria gonorrhoeae are common. • Symptoms of chlamydial infection develop after successful treatment of gonorrhea. • Reason: longer incubation period + β-lactam antibiotics are ineffective for C. trachomatis • Reiter’s syndrome • Urethritis, conjunctivitis, polyarthritis, mucocutaneous lesion • Usually occurs in young white man • Initiated by genital infection with C. trachomatis.

15. (3) Adult Inclusion Conjunctivitis • Acute follicular conjunctivitis with mucopurulent discharge • Mostly occur in sexually active adults (18-30 yr) with genital infection with serotypes A, B, Ba, D to K. • Acquired by auto-inoculation, oral-genital contact

16. (4) Newborn Inclusion Conjunctivitis • 25% infants acquired from mothers with active genital infections • Swollen and hyperemic eyelids • Long (>12 months) disease course if untreated and are at risk for C. trachomatis pneumonia

17. (5) Infant Pneumonia • A diffuse interstitial pneumonia • Occur in 10-20% infants that exposed to the pathogen at birth

18. (6) Lymphogranuloma venereum (LGV)花柳性淋巴肉芽腫 • A chronic sexually transmitted disease caused by C. trachomatis L1, L2, L2a, L2b, L3. • More common in men, with male homosexuals being the major reservoir. • Small, painless lesions (papule or ulcer) at site of infection (genitalia). Fever, headache, myalgia. • Inflammation and swelling of regional lymph nodes (inguinal nodes) - painful buboes (橫瘻), rupture, fistulas formation. • Proctitis (直腸炎) is common in women. • Resolve spontaneously or progress to ulceration or genital elephantiasis (象皮病).

19. Bubonic plague – Inguinal buboes with edema

20. Lab diagnosis • Symptomatic infections are easier to diagnosis than asymptomatic infections as more chlamydiae present in specimen. • For trachoma: cytology – Giemsa-stained cell scrapings • Quality of the specimen is important. Specimens must be obtained from the involved site; pus or exudate is inadequate. • For genital infections: culture – HeLa, MaCoy, Hep-2 cells • Iodine stain to detect inclusions (=RBs) • The most specific methods for diagnosis.

21. Iodine-stained Chlamydia trachomatis inclusion bodies (arrows)

22. Lab diagnosis • Nucleic acid amplification tests (NAATs) • Test of choice for lab diagnosis of C. trachomatis infection • First-void urine / urethral discharge • Amplification of a specific sequence, then detecting with a species-specific probe • Serologic tests • Good for LGV. Limited value for adult urogenital infections, cannot differentiate between current and past infections; • CF test or EIAs: genus-specific LPS as antigen, fourfold increase or >1:256 • MIF test: species- and serovar-specific antigen (MOMPs)

23. T/P/C • Resistance to penicillin (lack peptidoglycan) • Doxycycline for LGV • Azithromycin or doxycycline for ocular and genital infections in adult • Erythromycin for newborn conjunctivitis and pneumonia • Improve sanitary conditions – essential for prevention • Safe sex practices

24. 2. Chlamydophiliapneumoniae • Was first isolated from the conjunctiva of a child in Taiwan - TWAR strain. • An important cause of sinusitis, pharyngitis, bronchitis, and pneumonia. • Infection is common, especially inadults and transmitted person-to-person by respiratory secretions.

25. Clinical disease • Most infections are asymptomatic or mild - persistent cough. • Cannot be differentiated with other atypical pneumonia - Mycoplasma pneumoniae, Legionella pneumophila, and respiratory viruses. • Detected in atherosclerotic lesions in blood vessels. However, the role in the development of atherosclerosis is not clear.

26. Lab diagnosis • Diagnosis is difficult • Do not grow in cell lines used for isolation of C. trachomatis • NAATs are OK with large inter-laboratary variation. • Micro-immunofluorescence (MIF) test • The only acceptable serodiagnotic test (specific) • A single IgM titer > 1:16 (=recent infection) or a fourfold increase in IgG titer (paird acute and convalescent phase sera)

27. T/P/C • Macrolides (erythromycin), doxycycline • Ubiquitous present, control is difficult

28. 3. Chlamydophilia psittaci (鸚鵡熱披衣菌) • Caused Psittacosis (parrot fever). • The natural reservoir is any species of birds (Ornithosis, 飼鳥病) • Also infect sheep, goats, cows, and humans • High risk groups: veterinarians, zookeepers, pet shop workers, employees of poultry industry.

30. Pathogenesis • Inhalation of dried bird excrement, urine, or respiratory secretions; person-to-person transmission is rare. • Bacteria firstspread to and multiply in reticuloendothelial cells of liver and spleen  necrosis • Thenhematogenous spread to lung and other organs via circulation • Lmphocytic inflammation in lung, edema, necrosis, mucous plugs in bronchioles cyanosis and anoxia

31. Clinical disease • Asymptomatic infection • Flu-like illness: high fever, headache, chills, myalgia • Serious pneumonia • CNS involvement is common (headache, encephalitis, convulsion, coma), • GI symptoms (nausea, vomiting, diarrhea), hepatomegaly, splenomegaly

32. Diagnosis for C. psittaci • Complement fixation test of paired acute and convalescent phase sera • Confirmed by species-specific MIF test • Tetracyclines or macrolides • No need of isolation of patients and prophylaxia • No vaccine available • Treat birds with chlortetracycline HCl for 45 days. Treatment for C. psittaci

33. Chapter 44Rickettsia and OrientiaChapter 45Ehrlichia, Anaplasma, Coxiella Rickettsia Howard Ricketts Ehrlichia Paul Ehrlich Coxiella Harold Cox (Historically classified in Rickettsiaceae)

34. Order Rickettsiales Family RickettsiaceaeGenena Rickettsia Orientia Family AnaplasmataceaeGenena Ehrlichia Anaplasma Neorickettsia Wolbachia

35. Rickettsia (also Ehrlichia) is unstable and die quickly outside host cells. • Coxiellahighly resistant to desiccation, remain viable in environment for months to years. Obligate intracellularparasites. After phagocytosis • Rickettsia and Orientia: degrade phagosome membrane by producing phospholipase, multiply in cytoplasm and nucleus of endothelial cells • Ehrlichia and Anaplasma: multiply in cytoplasmic vacuoles (= phagosomes) of hematopoietic cells • Coxiella: multiply in phagolysosome of monocytes and macrophages

36. Chapter 44 Rickettsia and Orientia • G(-) bacilli, with a minimal peptidoglycan layer (stain poorly with Gram stain) and LPS (weak endotoxin activity) • Maintain in animal and arthropod reservoirs (ticks, mites, lice, fleas by transovarian transmission). • Transmitted to humans by arthropod vectors • Humans are accidental hosts: acquired by arthropod bite or contact of arthropod excreta with abraded skin

37. Pathogenesis • No toxins, no immunopathology • Rickettsia replicate in endothelial cells, cause cell damage and blood leakage, vasculitis, microthrombi, focal ischemia, hemorrhage, skin rash. • Hypovolemia, hypoproteinemia, reduced perfusion, organ failure.

38. Important Rickettsial Diseases • Spotted fever group 斑疹熱 R. rickettsii RMSF (>90%) R. akari Rickettsialpox (100%) • Typhus group 斑疹傷寒 R. prowazekii Epidemic typhus (40-80%) R. typhi Murine typhus (50%) O. tsutsugamushi Scrub typhus (<50%) (Parentheses: % of rash, 紅斑) • The distribution of rickettsial diseases (restricted area or worldwide) is determined by the distribution of the arthropod hosts/vectors.

39. Rocky mountain spotted fever (RMSF) • Have a restricted geographic and seasonal distribution, corresponding to tick activity. • R. rickettsii is maintained in hard ticks (wood tick and dog tick) by transovarian transmission. • Transmitted to humans by tick bite (need >6h to establish infection). • High fever, chills, headache, skin rash (>90%, extremities to trunk) • Respiratory failure, encephalitis, renal failure.

40. Diagnosis is urgent, identify key clinical signs – rash; the prognosis depends on the duration of illness fatality 10-25% if untreated • Culture: buffy coat of blood or skin biopsy; tissue culture or embryonated eggs (danger) • Microscopy: Giemsa stain; FA staining of biopsy tissue specimens for antigen detection • Serology: microimmunofluorescence (MIF), detect antibodies against MOMP and LPS antigens; both specific and sensitive • Nucleic acid-based tests: PCR + gene sequencing of a variety of genes • The traditional Weil-Felix test: not recommended for use

41. Treatment /Prevention/Control: • Appropriate therapy would result in good prognosis (e.g., doxycycline) • No vaccine • Prevent tick bites (can survive for as long as 4 years without feeding)

43. Rickettsialpox • R. akari • Infections are transmitted to humans from rodents reservoir by bite of infected mites (transovarian transmission) • Cosmopolitan distribution • Clinical disease – biphasic • Papule at site of bite, ulceration, eschar formation (焦痂) (differentiate with cutaneous anthrax) • High fever, severe headache, chills, sweats, myalgias, photophobia, generalized rash (100%), complete healing 2-3 wks.

45. Epidemic (louse-borne) typhus流行性(蝨型)斑疹傷寒 • R. prowazekii • Humans are the primary reservoir with person-to-person transmission by human louse (the bacteria kill the lice 2 to 3 wk after infection; no transovarian transmission). • Epidemics occur among people living in crowded, unsanitary condition - war, famine, or natural disaster. • High fever, severe headache, myalgias, skin rash (20-80%), complete recovery >3 months

46. Brill-Zinsser Disease • Bacteria may remain for years. • A recrudescent, mild form of epidemic typhus arising years after the initial attack.

48. Diagnosis: • MIF test for detection of antibody T/P/C: • Tetracyclines, Chloramphenicol • Louse-control • A formaldehyde-inactivated vaccine is available

49. Endemic (murine) typhus地方性(鼠類)斑疹傷寒 • R. typhi transmits to man from rodent reservoir hosts by the bite of rat flea and cat flea. • Endemic all over the world, primarily in warm, humid areas. • Fever, severe headache, myalgias, chills, skin rash (50%) on chest and abdomen for 3 weeks.