Determination of Dominant Serovars and Molecular Analysis of hly and iap Genes Related to Listeria monocytogenes Strains Isolated from Spontaneous Human Abortions in Tehran

Listeria monocytogenes, a gram positive, facultative, intracellular bacterium is the causative agent of listeriosis that is transmitted to human through raw and ready-to-eat foods. The aim of the present study was to determine dominant serovars of L. monocytogenes isolated from spontaneous abortion using phenotypic and genotypic methods.

In present study, 258 clinical specimens including placental secretions, vaginal swabs and blood samples from 123 patients with abortion were selected in sterile condition then bacteriological, serological and molecular tests were conducted; dominant serotypes were identified by Multiplex PCR.

Out of 28 (%18.8) isolates of L. monocytogenes 21 (%17.7), 5 (%5.7) and 2 (%3.37) were isolated from placental secretions, vaginal swabs and blood respectively. Maximum and minimum isolated of bacteria related to placental secretions and vaginal swabs with 21 and 2 isolates respectively, of which 14 (%50) 1/2a, 10 (%35.7) 4b and 4 (%14.6) 2c serovars were reported for the first time. All of serovars played a key role in the spontaneous abortion as dominant and common serotypes in Iran. All of the isolates 28 (%22.76) showed hlyA gene and 24 isolates (%19.57) were positive for iap gene and compaired with control group there was significant different between the two groups (P<0.0002).

The present study showed the isolation dominant and common serotypes of L. monocytogenes from spontaneous abortion and demonstrated that the presence of hlyA and iap were effective genes in increasing aggressive and pathogenicity. Serotypes that lacked the iap gene have less pathogenicity and influenced the pathogenesis in mice. It was also concluded that in the absence of access to molecular tests, performing PI-PLC, Congored and in vivo pathogenicity can be effective in detecting pathogenic serotypes from non-pathogenic L. monocytogenes.