The following is not a method of isolation of chlamydia from clinical specimens -
Ans. is 'b' i.e., Enzyme immunoassay Although chlamydia are bacteria, they are obligate intracellular parasites, therefore cultures and other diagnostics tests for chlamydia require procedures much like those used in diagnostic virology laboratories rather than those used in bacteriology laboratories.Diagnosis of chlamydia.Four approaches are available for the laboratory diagnosis of chlamydial infectionsMicroscopic demonstration of elementary or inclusion bodiesIsolation of chlamydia (culture)Antigen detection & Nucleic acid hybridizationSerologyMicroscopic demonstration of elementary or inclusion bodies,Chlamydial elementary bodies and inclusions are large enough to be seen under the light microscopeCytological examination is important and useful only in the examination of conjunctivitis and trachoma caused by chlamydia trachomatis.Another method available for microscopic examination is Immunoflorescence using monoclonal antibody.Isolation of chlamydia.Isolation of chlamydia can be done by inoculation into:embryonated eggsexperimental animals (Hi) tissue culturesEmbryonated eggs -Chlamydia can be grown in yolk sac of 6-8 days old chick embryosIsolation by egg inoculation is tedious and relatively insensitive and has been replaced by tissue cultures. Tissue cultureCell culture is the preferred method for isolation of chlamydiaCell cultures for Chlamydia Trachomatis } - McCoy cells Chlamydia Psittaci } Chlamydia pneumonia -HL or HEp+2 cellsCell cultures used for isolation of chlamydia are pretreated by irradiation or chemicals.Pretreatment with DEAD-dextran reduces the electrostatic barrier to infection before centrifugation of chlamydial or clinical specimen on to the cells. Thus it promotes contact between chlamydial particles and cell monolayer increasing chance of isolation.The cells are then usually incubated in an antimetabolite such as cycloheximide to favour chlamydial competition for host amino acid pool.Antigen detection & Nucleic acid hybridization Antigen detection can be done by two methodDirect florescent antibody (DFA) demonstration -The DFA uses monoclonal antibodies directed against a species specific antigen on the chlamydial major outer membrane protein (MOMP)Enzyme linked immunoassays (EIA'S) -This test detects the presence of genus specific lipopoly saccharide antigens extracted from the elementary bodies in the specimen.Nucleic acid detection * Molecular methods used for the detection of chlamydiae arePolymerase chain reactionLigase chain reactionSerologyAntibodies against chlamydia can be used for diagnosis.A fourfold rise in titres is diagnostic.Serological test are not useful in the diagnostic of genital chlamydia infections because of high prevalence of chlamydial genital tract infection is some societies.Also knowHypersensitivity test -Demonstration of hypersensitivity by skin testing (Frei's test) was widely used formerly for diagnosis of L.G.V. but has been given up because of false positive results.Note:-Enzyme immunoassay is not a method of isolation.I am not sure whether irradiated BHK cell are used in isolation of chlamydia.
Yolk sae inoculation
Enzyme immunoassay
Tissue culture using irradiated McCoy cells.
Tissue culture using irradiated BHK cells
Bacteria