Evaluating two indirect hemagglutination methods in diagnosis of listeriosis in comparison with indirect immunoflourecens

Introduction: Ba ct e rimi a res u lte d fro m Lis t eri a mono cyt ogen e s lea ds to va rIOUS complications including abortion . While cult uring the specimen is a crocial me thod in diagn osing of liste ri osi s, it has low se ns it ivity (because o f the few number of bacteria in specimens) and takes long time. Serological methods are used routinely in many diagnostic laboratories because of improved time and sensitivity. Materials and methods: IHA (indirect hemagglutination) was performed using fract ion 1, obtai ne d from ge l chroma tograp hy of sonica te d liste r ia monocytoge ne s cr ude antige ns. IHA th rou gh pot e l's me th od was ca rried on. Se ns it ivity and specific ity of th ese methods compa re d with current IFA (immunotlourecens assay) in diagnos ing the Listeriosis. The titers of antibody against Listeri a mon ocytoge nes were de te rmine d in se rums of 207 women having at le ast o ne abortion. Among this group serums of 96 women by IHA with soluble antigens in fra ction I and 82 women by IHA with soluble antigen in potel's method were tes ted . Results: In IFA (sensitivity 70% and spec ificity 50%),83.5% had valuable titer s of antibody. Niether crude antige n n or t hr ee fr ac tio ns we re suitab le for IHA, bu t al182 serums (pote l's method) showing 1/4 to 1/256 tite rs (se nsit ivity 36% and spec ificity 96%) . Conclusion: IFA is the most cu rrent method b ut, because o f h igh sensit ivity a nd low specific ity a more confident meth od is required. This study shows antigenic fraction s of listeria monocytoge nes are no t suitab le for IHA, while cha ng ing the co nd itio n of cu ltu re in po tel's method leads to the applicable antigen for IHA. Lack of correlation betwee n IFA and potel's IHA indicate that the nature of antigens arc diffe rent in bot h me thods. Thus it is recommended to use IFA for screening and simultaneously potel's IHA (because of high specificity).