The investigation of molecular characterization of presumptive Listeria monocytogenes isolates from a food-processing environment

Document Type : Full paper (Original article)


Duhok Research Centre, College of Veterinary Medicine, University of Duhok, Duhok, Iraq


Background: Listeria is a Gram-positive, non-spore forming, facultative anaerobic intracellular bacterium. The most important pathogens in mammals include Listeria monocytogenes and Listeria ivanovii. The former generally causes disease and death in both humans and animals while the latter performs sporadically and primarily causes illness in ruminants. Aims: The aim of this project was to use conventional and molecular techniques to determine whether the provided samples were L. monocytogenes, and whether they were genetically similar or different. Methods: The provided presumptive Listeria cultures isolated from industrial processed food are conventionally assumed to be L. monocytogenes. All samples were cultured on brain heart infusion agar and broth first and then on blood agar. Later, hly gene amplification was applied. Results: The provided culture phenotypically resembled L. monocytogenes as it caused haemolysis on blood agar plates; however, the absence of the hly gene revealed that they were genotypically different. 16S rRNA confirmed three species of Listeria species including L. grayi, L. welshimeri and L. ivanovii. The results from 16S rRNA sequencing confirmed the results obtained from hly gene amplification. Conclusion: Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC PCR) confirmed that all bacterial cultures were isolated from different sources depending on their ERIC PCR profile variation.


Acciari, VA; Torresi, M; Migliorati, G; Di Giannatale, E; Semprini, P and Prencipe, V (2011). Characterisation of Listeria monocytogenes strains isolated from soft and semi-soft cheeses sampled in a region of Italy. Vet. Ital., 47: 15-23.
Allerberger, F (2003). Listeria: growth, phenotypic differentiation and molecular microbiology. FEMS Immunol. Med. Microbiol., 35: 183-189.
Atil, E; Ertas, H and Ozbey, G (2011). Isolation and molecular characterization of Listeria spp. from animals, food and environmental samples. Vet. Med., 56: 386-394.
Bosshard, PP; Abels, S; Zbinden, R; Böttger, EC and Altwegg, M (2003). Ribosomal DNA sequencing for identification of aerobic Gram-positive rods in the clinical laboratory (an 18-month evaluation). Clin. Microbial., 41: 4134-4140.
Chen, J; Cheng, C; Lv, Y and Fang, W (2013). Genetic diversity of internalin genes in the ascB-dapE locus among Listeria monocytogenes lineages III and IV strains. Basic Microbiol., 53: 778-784.
Chen, Y; Ross, WH; Whiting, RC; Van Stelten, A; Nightingale, KK; Wiedmann, M and Scott, VN (2011). Variation in Listeria monocytogenes dose responses in relation to subtypes encoding a full-length or truncated internalin A. Appl. Envirom. Microbial., 77: 1171-1180.
Duan, H; Chai, T; Liu, J; Zhang, X; Qi, C; Gao, J; Wang, Y; Cai, Y; Miao, Z; Yao, M and Schlenker, G (2009). Source identification of airborne Escherichia coli of swine house surroundings using ERIC-PCR and REP-PCR. Envirom. Res., 109: 511-517.
Guide to AGRF Sanger Routine Sequencing Service (2012). (AGRF). Viewed at 1st November 2013. http://www.agrf.
Hellberg, RS; Martin, KG; Keys, AL; Haney, CJ; Shen, Y and Smiley, RD (2013). 16S rRNA partial gene sequencing for the differentiation and molecular subtyping of Listeria species. Food Microbial., 36: 231-240.
Hogg, G; Tan, A and Gregory, J (2013). Listeria surveillance in Australia from the laboratory perspective. Microbiol. Aust., 34: 90-92.
Jadhav, S; Bhave, M and Palombo, EA (2012). Methods used for the detection and subtyping of Listeria monocytogenes. J. Microb. Meth., 88: 327-341.
Laksanalamai, P; Joseph, LA; Silk, BJ; Burall, LS; L. Tarr, C; Gerner-Smidt, P and Datta, AR (2012). Genomic characterization of Listeria monocytogenes strains involved in a multistate listeriosis outbreak associated with cantaloupe in US. PLoS One. 7: 42-48.
Lambertz, ST; Ivarsson, S; Lopez-Valladares, G; Sidstedt, M and Lindqvist, R (2013). Subtyping of Listeria monocytogenes isolates recovered from retail ready-to-eat foods, processing plants and listeriosis patients in Sweden 2010. Inter. J. Food Microbial., 166: 186-192.
Liu, D (2008). Handbook of Listeria monocytogenes. 1st Edn., US, NW, CRC Press. P: 139.
Mammina, C; Aleo, A; Romani, C; Pellissier, N; Nicoletti, P; Pecile, P; Nastasi, A and Pontello, MM (2009). Characterization of Listeria monocytogenes isolates from human listeriosis cases in Italy. Clin. Microbial., 47: 2925-2930.
Marian, MN; Sharifah Aminah, SM; Zuraini, MI; Son, R; Maimunah, M; Lee, HY; Wong, WC and Elexson, N (2012). MPN-PCR detection and antimicrobial resistance of Listeria monocytogenes isolated from raw and ready-to-eat foods in Malaysia. Food Control. 28: 309-314.
Orsi, RH; Bakker, HCD and Wiedmann, M (2011). Listeria monocytogenes lineages: genomics, evolution, ecology, and phenotypic characteristics. Med. Microbial., 301: 79-96.
Palumbo, JD; Borucki, MK; Mandrell, RE and Gorski, L (2003). Serotyping of Listeria monocytogenes by enzyme-linked immunosorbent assay and identification of mixed-serotype cultures by colony immunoblotting. J. Clin. Microb., 41: 564-571.
Prophet, EB; Mills, B; Arrington, JB and Sobin, LH (1992). Laboratory methods in histotechnology. 1st Edn., American Registry of Pathology Washington, D.C.
Rohwer, F; Breitbart, M; Jara, J; Azam, F and Knowlton, N (2001). Diversity of bacteria associated with the Caribbean coral Montastraea franksi. Cor. Re., 20: 85-91.
Schlech III, WF; Lavigne, PM; Bortolussi, RA; Allen, AC and Haldane, EV (1983). Epidemic listeriosis: evidence for transmission by food [Listeria monocytogenes]. New Engl. J. Med., 308: 203-206.
Soni, DK; Singh, RK; Singh, DV and Dubey, SK (2013). Characterization of Listeria monocytogenes isolated from Ganges water, human clinical and milk samples at Varanasi, India. Infec. Genet. Evol., 14: 83-91.
Vázquez-Boland, JA; Kuhn, M; Berche, P; Chakraborty, T; Domı́nguez-Bernal, G; Goebel, W; González-Zorn, B; Wehland, J and Kreft, J (2001). Listeria pathogenesis and molecular virulence determinants. Clin. Microbial., 14: 584-640.
Zhang, D; Zhang, H; Yang, L; Guo, J; Li, X and Feng, Y (2009). Simultaneous detection of Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Escherichia coli O157: H7 in food samples using multiplex PCR method. J. Food Saf., 29: 348-363.