In vivo assessment of antimicrobial activity of enterocin CRL35 and Enterococcus mundtii CRL35 in a murine model of pregnancy-associated Listeria monocytogenes infection

SAAVEDRA L, SALVUCCI E, HEBERT E, HARO C, VIGNOLO G AND SESMA F

Kosice-Slovakia

Congreso; International Scientific Conference on Gastro-Intestinal Microbial Ecology; 2010

Pavol Jozef Safarik Univeristy

In vivo assesment of antimicrobial activity of enterocin CRL35 and Enterococcus mundtii CRL35 in an murine model of pregnancy-associated Listeria monocytogenes infection L.Saavedra, E. Salvucci, E. Hébert, C.Haro, G.Vignolo and F. Sesma. Centro de Referencia para Lactobacilos (CERELA-CONICET), Chacabuco 145, Tucumán, 4000, Argentina. lucila@cerela.org.ar Introduction: Since the 80s, Listeria monocytogenes has been recognized as a foodborne pathogen that can be acquired mainly by the comsumption of refrigerated and ready-to-eat products. Pregnant individuals are among the most susceptible population for Listeria infection where the consequences may result in misscarriage and fetal death. Enterococcus mundtii CRL35 produces enterocin CRL35, a subclass IIa bacteriocin active against Listeria. Previous studies in our lab demonstrated that combinations of enterocin CRL 35 with certain antibiotics strongly increase their potency leading to marked reduction of their dose. These results suggest a potential application of such combinations in the medicine or pharmaceutical fields. As a first step in this direction we set up a murine model of listeriosis to test the effectiveness of enterocin CRL35 and its producer strain. Methods: E.mundtii CRL 35 was grown for 16 h at 37 ºC in LAPTg broth. Enterocin CRL35 was purified (EP) from a 16 h culture supernantant by our standard lab procedure. A murine model of pregnancy associated Listeria infection was achieved. Five to six week-old female BALB/c mice were orally infected with Listeria monocytogenes FBUNT at day 14 and sacrified on 17 day of pregnancy. Mice were randomly divided in groups that received: a) L.monocytogenes FBUNT (5x 109 UCF in 200 µl) b L.monocytogenes FBUNT (5x 109 UCF in 200 µl) plus a treatment of 65 µg (EP) per animal every 12h c) E.mundtii CRL35 (2 x 109 UFC in 200 µl) and 5 h later infected with Listeria (5x 109 UCF in 200 µl) d) PBS (200 µl) e) 65µg (EP) every 12 h. Mice were anaesthetized and killed after blood collection by cardiac puncture. Liver, spleen and fetus were aseptically taken, homogenized and plated on Listeria selective agar (Oxoid) and Brain Heart Infusion (BHI). Plates were incubated at 37ºC for 48h. Viable counts were expresed as log colony-forming units (CFU) per gram of organ. Changes in weight, food and fluid intake as well as hematologic parameters were also analyzed. Results: The administration of a single dose of L.monocytogenes FBUNT resulted in the translocation of the pathogen to liver and spleen but it was not detected in fetus.Bacteriological analysis demonstrated that the administration of enterocin CRL 35 markedely reduced the CFU count of Listeria cells in liver and spleen. On the other hand, the administration of E.mundtii CRL 35 also decreased Listeria counts but preventive treatment (3days) with this strain resulted in unspecific translocation of other microbiota. None of the groups showed any remarkable changes of hematological parameters, food and fluid intake. Conclusion: These results evidenced that enterocin CRL35 might represent a good candidate for potential  pharmacological or medical applications.Although more studies need to be done in order to pursue this issue.