International Journal of Sciences: Basic and Applied Research (IJSBAR) ISSN 2307-4531 (Print & Online) http://gssrr.org/index.php?journal=JournalOfBasicAndApplied --------------------------------------------------------------------------------------------------------------------------- 277 Antimicrobial Susceptibility of Listeria Species from Abattoir Effluent in Port Harcourt, Nigeria. Francis S. Ire a , Onoriode C. Eruteya b *, Precious O. Obiebi c a,b,c University of Port Harcourt, East-West road, Choba, Port Harcourt, 500001, Nigeria. a Email: frankire4@yahoo.com b Email: onoriode.eruteya@uniport.edu.ng c Email: loveprecious321@gmail.com Abstract Untreated abattoir effluent constitutes a reservoir for the spread of important pathogens including Listeria monocytogenes, the etiologic agent of listeriosis. This study investigated the presence and antimicrobial resistance profile of Listeria species from abattoir effluent in some Port Harcourt communities using standard conventional and molecular methods. Listeria were detected in 26% of the samples examined. The resulting isolates were identified as L. grayi (53.85%), L. welshimeri (38.46%) and L. innocua(7.69%). The Listeria isolates showed varying resistance to cotrimoxazole (44.2%), chloramphenicol (34.6%), tetracycline (46.2%), streptomycin (75%), augmentin (94.2%), gentamycin (19.2%), erythromycin (34.6%) and cloxacillin (100%). All three disinfectants were not effective against Listeria species at concentrations of 12% and 25%. At 50% and 100% disinfectant concentration, dettol was the most effective followed by JIK and lastly, izal. The presence of Listeria species in abattoir effluent and levels of resistance to commonly used antibiotic and disinfectants portends danger to animals and human population hence the need for adequate treatment of effluent before discharged into the environment. Keywords: Abattoir effluent; antibiotics; disinfectant; Listeria species. ------------------------------------------------------------------------ * Corresponding author.