Identification of Listeria monocytogenes virulence factors in women with abortion by polymerase chain reaction

Abstract

Background: Listeria monocytogenes, as one of the foodborne pathogens, is a causative agent of listeriosis. The transfer of L. monocytogenes bacteremia in pregnant women occurs as self-limited flu-like symptoms, but it may result in abortion, stillbirth or premature birth of the infected baby. One of the best methods for detection of this bacterium is polymerase chain reaction (PCR). Objectives: The purpose of this study was detection of virulence factors (hlyA and plcA) of L. monocytogenes in women with abortion, using PCR. Results: Out of 96 samples, 16 isolates of L. monocytogenes by PCR (plcA and hlyA) and four isolates by culture were identified. There was a significant difference between PCR and culture methods (P = 0.003). The results of this study showed that PCR was more sensitive and specific than culture method. There was also a significant association between the bacteria and hlyA and plcA genes and human abortion and between patients with abortion precedence and education. Patients and Methods: In this pilot and cross-sectional study, 96 patients with abortion admitted in educational university, Tehran, Iran were surveyed for L. monocytogenes by PCR and culture methods. Some variants like age, occupation, history of abortion and education were considered for all patients. Vaginal swabs and secretions were transferred to trypticase soy broth as the transport media and then all the samples were transferred to a microbiology laboratory. The tubes were incubated in 4 °C and the specimens were cultured on PALCAM media. The isolates were verified by Gram staining, catalase and oxidase test, methyl red-Voges-Proskauer (MR-VP), sugar fermentations and motility in 20-25°C. Then, PCR was performed for the extracted DNAs. Data were analyzed by SPSS software version 17, and χ2 (Chisquare test). Conclusions: Based on our study, plcA and hlyA played a key role in the virulence determination of L. monocytogenes. Data analysis also showed that L. monocytogenes could be a causative agent of abortion in pregnant women.