babylon university
college of medicine
dep. of microbiology
assist. proph. dr.ilham alsaedi
chlamydia
the name chlamydia is derived from the characteristic appearance of inclusion bodies produced by these agents which are seen enclosing the nuclei of infected cells as cloak or mantle (chlamys means mantle).
three species are important pathogenic for human c. trachomatis, c. pneumoniae, and c. psittaci.
important properties:
1- obligate intracellular parasites closely related to g-ve bacteria.
2- on the basis of
a-antigenic composition
b- intracellular inclusions
c- sulfonamide susceptibility
and d-disease production
chlamydia are divide into 3 species:
c. trachomatis, c. pnumoniae, c. psittaci
3- they are having properties intermediates between bacteria and viruses. they differ from viruses in:-
a- like bacteria, they possess both dna and rna.
b- they multiply by binary fission, viruses never do.
c- they have a cell wall.
d- they have ribosomes, virsus never do.
e- havevarity of active enzymes.
f- there growth can be inhibited by antibiotics.
4- chlamydia possess 2 types of antigens located in the cell wall. these are heated-stable lipoprotein-carbohydrate complex and 2-keto-3-deoxy-octonic acid. the toxic effects of chlamydia are associated with these antigens.
5- the chlamydia is small, round to avoid( coccoid) cells that vary morphologically during their replication cycle.
virulence factors:-
1-adhesions factors:
chlamydia have a high affinity for host epithelial cells of (urethra, conjunctiva, cervix, etc…) by this factor.
2-phagocytized chlamydia prevent fusion of lysosome to phagosome and thus, escape intracellular structure by lysosomalenzyme, and the organisms persist within phagosome cell.
3-production of heat-labile toxin.
transmission and epidemiology:
1- c. trachomatis:(infected only human):
genital chlamydial infection and inclusion conjunctivitis are sexuallytransmitted disease that are spread by contact with infected sex partners. neonatal inclusion conjunctivitis originates in the mother´s infected genital tract also c. rachomatis caused eye infection (trachoma).
trachoma and inclusion conjunctivitis(tric) are major problem in world wide. its most frequently found in developing countries in dry, hot regions such as africa and asia.
2- c. pneumoniae:(infects only human)
transmitted from person to person by aerosol(air dropinglets).infection with this organisms is world wide.
3- c. psittaci:
outbreaks of human disease can occur whenever there is close contact between humans and infected bird. humans are infected by inhaling organisms in dry bird feces or dust contaminated with bird feces.
pathogenesis and clinical findings:
the pathogenesis (mechanism) of chlamydial disease is not understood, but it produce heat-labile-toxin, and it is intracellular, this fact explain, it resistance to lysozyme action of phagosome.
c. trachomatis cause the following disease:
a- eye infection: two syndromes involving the eye are caused by different antigenic types of this organism.
1- is caused by immune type a, b, and c. incubation period is 3-10 days.
2- inclusion conjunctivitis:is caused by immunotype d-k.
the disease is acute that common in infants but less in adults. inclusion conjunctivitis of newborn is characterized by muco purulent conjunctivitis after 7-12 days of delivery.
b- genital infection:
serovar d-k, cause sexually transmitted disease. in men it cause non gonococcal urethritis. in women, cause urethritis, cervicitis and pelvic inflammatory disease which can lead to sterility and predisposes to ectopic pregnancy up to 50% of nongonococcal urethritis(men) or the urethral syndrome(women) in attributed to chlamydia and produce dysuria, non purulent discharge.
c. pneumoniae:
cause upper and lower respiratory tract infection, especially bronchitis and pneumonitis, in young adults (atypical pneumonia, is also called twar recognized in 1989 in patient in taiwan with acute respiratory infection).atypical pneumonia may caused by other organisms such as mycoplasma pneumonia, legionella pneumophila, coxiellaburnetii.
c. psittasi
cause psittacosis in human and ornithosis in birds. infection occurs among population who contact and continued with infected birds(psittacine birds: parrots parakeets).
the bacteria infect human lungs primarily. the infection may be a symptomatic or may produce high fever and pneumonia. the infection of domestic and wild birds with similar agent which exhibit as of infection.
immunity:
a little is known about active or potential protective immunity. immunity in animals and human is incomplete. live or inactivated vaccine induces only partial resistance in animal. they have not been used in human.
lab. diagnosis:
a- chlamydia can been seen by light microscope whene the cell stained with gimsa or iodin.the gram stain is not useful.
b- chlamydia can been grown in cell culture treated with cycloheximide,which inhibits host cell but not chlamydial protein synthesis.they also can be grow in yolk sac of embryonated chicken eggs.
c- serologictests:elisa,cft.
d- nucleicdetection:pcr.
control on chlamydial infection:
a- prophylaxis:
1-personal hygiene
2-safe sexual behavior
3-addition of antibiotics agent in bird feed.
b- treatment: tetracycline, erythromycin, are very effective on chlamydial infection.
c- no vaccine against chlamydial infection.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .