Isolation and Identification of Listeria Species

Isolation and Identification of Listeria SpeciesAlesha Coleman-McCallumTitleIsolation and Identification of Listeria species from chicken sample victimisation Palcam broth (pre-enrichment), UVM 11 broth ( discriminating enrichment), Palcam and Oxford agars (selective plating) also standation using biochemical tests.ObjectivesTo isolate Listeria species from chicken sampleTo observe the reaction of listeria on selective specialityTo confirm the Listeria species using biochemical testsIntroductionListeria is a genus of aerobic parasitic, gram positive rod-shaped bacterium (Define, n.d). This genus has more than 10 species with the commonly encountered being Listeria monocytogenes, Listeria innocua, Listeria ivanovii, Listeria welshimeri, Listeria seeligeri, Listeria grayi, Listeria murrayi. Members of this genus ar extensively spread in the environment and maybe found in soil, plants, gastrointestinal tract of animal and humans. Listeria monocytogenes species is of great concern be cause it is pathogenic to humans and causes listeriosis. Listeriosis is a alimentborne illness (Hardy Diagnostics, 1996).Listeria monocytogenes is different from most bacteria since it can grow in the cold, salt, acid and air-tight conditions. The increased demand of ready to eat nutritions especially in first world countries has the potential of listeriosis more eminent. Pregnant women, older adults, young children and immunocompromised persons ar more susceptible to Listeriosis infections. therefrom cooking, pasteurization/applying heating steps to food, avoiding raw meat and milk/ moist or processed food and washing hands regularly may restrict the risk of infections. (FDA, 2004). According to Food Quality natural rubber USA 4 a dry and clean work environment is crucial in avoiding listeria outbreaks in the food industry.Methods for IdentificationMethods used in BI208 lab for identification of Listeria were Palcam broth (pre-enrichment) then UVM 11 broth for selective enr ichment step, Palcam (selective agent) and Oxford agars (selective and differential agent). For confirmation of species organism was plated on a blood agar to check for hemolysis. Biochemical test included SIM tube for motility, mannitol, D Xylose and L Rhamnose reactions obtained. Other methods that could be used to differentiate listeria species are Polymerase Chain Reaction (PCR), Rapid Identification Kits and Serological tests (MFHPB-07, 2012).ResultsTable showing results obtained from Listeria media reactionMediaObservationsReactionPalcam agarShiny, smooth, circular, convex colonies.No fermentationNo HydrolsisOxford AgarBlack colour around coloniesEsculin ReductionBloodCream, hilly,glistening coloniesNo Beta-hemolysisMannitolTransparent colonies banD XyloseTransparent coloniesNegativeL Rhamnose legerity yellow fermentation around coloniesPositiveSIM TubeUmbrella shaped growthPositiveGram Stain gram positive rodsAssuming Listeria monocytogenes maneuver was usedMediaExpected ResultsPalcam BrothCloudyUVM 11CloudyPalcam AgarNo fermentationPositive HydrolysisOxford AgarEsculin ReductionBloodBeta-hemolysisMannitolNegativeD XyloseNegativeL RhamnosePositiveSIM TubePositiveDiscussionListeria innocua was isolated from the chicken sample. Listeria innocua is not usually implicated in food born-illnesses however an isolated death in an elderly patient was reported (Perrin, Bemer and Delamare, 2003).Portions of chicken sample were first placed in pre-enrichment broth in disposition for stressed cells to become viable and all otherwise bacterial cells to multiply. Enrichment stage is to partially suppress unwanted organisms and allow listeria to thrive. Oxford agar (OXA) is both selective and differential. The selective properties of OXA agar give not allow gram negative organisms to grow while suppressing most gram positive organisms (Oxoid, n.d). The different property of OXA agar will allow some species of Listeria to be totally inhibited, growth with or with out blackened colonies (MFHPB-07, 2012). Palcam agar utilizes two indicator systems esculin and mannitol. Listeria monocytogenes changes esculin to a black complex around colonies exactly does not ferment mannitol. Therefore some gram positive organisms such as enterococci and staphylococci will ferment mannitol hence can be ruled out as contaminants (Oxoid, n.d). Blood agar was used to determine if the organism is beta-hemolytic. Other Biochemical tests were mannitol, D Xylose, L Rhamnose and SIM Tube to differentiate and confirm the species. Since Listeria monocytogenes is pathogenic to humans a 2 Class Sampling Plan would be used to asses if the chicken is fit for consumption. Different species of an organism may let on variable characteristics and maybe mistaken. Listeria species were found and should be deemed unacceptable for consumption. Further testing such as PCR which is very specific could be used to conclusively identify the species present.ConclusionsBased on the obje ctives previously outlined, isolation and Identification of Listeria species from chicken sample using Palcam broth method was very effective.ReferencesDefine,n.d. Listeria Genus. Retrieved February 22, 2017 from http//www.dictionary.com/browse/listeriaHardy Diagnostics, 1996. Food Borne-illneses Retrieved February 22, 2017 from https//catalog.hardydiagnostics.com/cp_prod/ confine/hugo/Listeria.htmFDA, 2004. Food-Borne Pathogenic Microorganisms and Natural Toxins Handbook The Bad Bug Book U.S. FDA/CFSAN. Center for Food Safety and Applied Nutrition, Food and Drug Administration, College park, MD.Food Quality Safety (formerly Food Quality),2007. Retrieved February 20, 2017 from http//www.foodqualityandsafety.com/article/prevent-and-control-listeriaJay, J.M.,Loessner, M.J. Golden, D. A. (2005). Modern Food Microbiology Indicator of Food Microbial Quality and Safety, 476-477. United States of America Springer Science+Business Media LLC .MFHPB-07 Method, November, 2012. The isolation of Listeria monocytogenes and other listeria species from food and environment samples using Palcam broth. Retrieved February 20, 2017 fromhttp//www.hc-sc.gc.ca/fn-an/res-rech/analy-meth/microbio/volume2-eng.phpMonique Perrin, Michel Bemer and Catherine Delamare, 2003. Fatal Case of Listeria innocua Bacteremia Journal of Clinical MicrobiologyOxoid, n.d. Enrichment Media for Listeria. Retrieved February 20, 2017 fromhttp//www.oxoid.com/uk/blue/prod_detail/prod_detail.asp?pr=CM0856org=91c=uklang=ENUS Government, n.d. Retrieved February 20, 2017 from https//www.foodsafety.gov/poisoning/causes/bacteriaviruses/listeria/Zimbro, M.J., Power D.A., Miller,M.M., Wilson, G.E., Johnson, J.A., (Revised 2009). Difco gun barrel Manual Palcam and Oxford Agar, Culture Media for Specific Groups of Microorganisms. United States of America Becton, Dickinson and Company.