Mohamed, Rasha I.Abdelmonem, , Mohamed A.Amin, Heba M.2019-12-182019-12-182018-02Adzitey F, Rahmat Ali GR, Huda N, Cogan T, Corry J (2013). Prevalence, antibiotic resistance and genetic diversity of Listeria monocytogenes isolated from ducks, their rearing and processing environments in Penang, Malaysia. Food Contr. 32:607-614. Aznar R, AlarcónB( 2003). PCR detection of Listeria monocytogenes: a study of multiple factors affecting sensitivity. J. Appl. Microbiol. 95:958-966. Behravesh CB, Jones TF, Vugia DJ, Long C, Marcus R, Smith K, Thomas S, Zansky S, Fullerton KE, Henao OL, Scallan E (2011). Deaths associated with bacterial pathogens transmitted commonly through food: Foodborne Diseased Active Surveillance Network (FoodNet), 1996-2005. J. Infect. Dis. 204:263-267. Bauer AW, Kirby WMM, Sherris JC, Turck M (1966). Antibiotic Susceptibility testing by a standardized single disc method. Amer J. Clin. Pathol. 45:493-496. Braga V, Vázquez S, Vico V, Pastorino V, Mota M I, Legnani M, Varela G (2017). Prevalence and serotype distribution of Listeria monocytogenes isolated from foods in Montevideo-Uruguay. Brazilian. J. Microbiol. 48(4):689-694. Byrne D V, Hofer E, Vallim DC, de Castro Almeida RC.(2016). Occurrence and Antimicrobial Resistance Patterns of Listeria Monocytogenes Isolated from Vegetables. Brazilian. J .Microbiol. 47(2):438-443. Charpentier E, Courvalin P (1999). Antibiotic resistance in Listeria spp. Antimicrob. Agents Chemother; 43:2103-2108. Chen M, Wu Q, Zhang J, Yan Z, Wang J (2014). Prevalence and characterization of Listeria monocytogenes isolated from retail-level ready-to-eat foods in South China. Food Control 2014: 38: 1-7 Colagiorgi A, Di Ciccio P, Zanardi E, Ghidini S, Ianieri A (2016). A Look inside the Listeria monocytogenes Biofilms Extracellular Matrix. Microorganisms 4(3):22. Cossart P, Vicente MF, Mengaud J, Baquero F, Perez-Diaz JC, Berche P( 1989). Listeriolysin O is essential for virulence of Listeria monocytogenes:direct evidence obtained by gene complementation. Infect. Immun.57:3629-3636. Dongyou L, Mark L, Jerald A, Frank WA (2005).Comparative assessment of acid, alkali and salt tolerance in Listeria monocytogenes virulent and a virulent strains. FEMS Microbiol. Lett. 243(2):373-378. Graves LM, Helsel LO, Steigerwalt AG, Morey RE, Daneshvar M I, Roof SE, Orsi RH, Fortes ED, Milillo SR, Den Bakker HC, Wiedmann M, Swaminathan B, Sauders BD (2010). Listeria marthii sp. nov., isolated from the natural environment, Finger Lakes National Forest. International J. Syst. Evol. Microbiol. 60:1280-1288. Hof H (2004). an update on the medical management of listeriosis. Expert. Opin. Pharmacother. 5:1727-1735. ISO 11290-1 (1996)/Amd 1. Modification of the isolation media and the haemolysis test, and inclusion of precession data. Geneva: International Organization for Standardization, International Electrotechnical Committee; 2004. Jaradat ZW, Schutze GE, Bhunia AK (2002). Genetic homogeneity among Listeria monocytogenes strains from infected patients and meat products from two geographic locations determined by phenotyping, ribotyping and PCR analysis of virulence genes. Int. J. Food Microbiol. 76:1-10. Kara R, Gokmen M, Akkaya L, Gok V (2015). Microbiological Quality and Salmonella spp., /Listeria monocytogenes of Spices in Turkey. Res. J. Microbiol. 10(9):440-446. Leclercq A, Clermont D, Bizet C, Grimont PA, Le Fle`che-Mate´os A, Roche SM, Buchrieser C, Cadet-Daniel V, Le Monnier A, Lecuit M, Allerberger F (2010). Listeria rocourtiae sp. Int. J. Syst. Evol.. Microbiol. 60:2210-2214. Ling-ling M, Li-qiao L, Ming Z, Lin-hua W, Xue-xia P, Jun-yan Z (2006). Serum type and drug resistance of Listeria monocytogenes in food. Chin. J Health Lab. Technol. pp. 1165-1166. Lopez J (2008). Listeria monocytogenes, in: OIE (Ed.), Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. www.oie.int/fileadmin/Home/eng/Health_standards/tahm/2.09.07_LIS TERIA_MONO.pdf. National Committee for Clinical and Laboratory Standards (NCCLS) (2012). Performance Standards for Antimicrobial Disc Susceptibility Tests: Thirty-Two Informational Supplement M100-S22.National Committee for Clinical Laboratory Standards Institute. Wayne, Pa, USA. Ottaviani F, Ottaviani M, Agosti M (1997) Esperienza su un agar selettivo e differentiale perListeria monocytogenes. Industries Alimentarius 36:1-3. Rahimi E, Shakerian A, Raissy M (2012). Prevalence of Listeria species in fresh and frozen fish and shrimp in Iran. Ann Microbiol. 62(1):37- 40. doi:10.1007/s13213-011-0222-9. Rodríguez-la D, Herna M, Scortti M, Esteve T (2004). by Real-Time PCR : Assessment of hly , iap , and lin02483 Targets and AmpliFluor Technol. 70(3):1366-1377. doi:10.1128/AEM.70.3.1366. Salcedo C, Arreaza L, Alcala B, De La Fuente L, Vazquez JA (2003). Development of a multilocus sequence typing method for analysis of Listeria monocytogenes clones. J. Clin. Microbiol. 41:757-762. Soni DK, Singh M, Singh DV, Dubey SK (2014). Virulence and genotypic characteriza-tion of Listeria monocytogenes isolated from vegetable and soil samples. BMCMicrobiol. 14:1. Suriyapriya S, Selvan P, Porteen K, Kannan SS (2016). Prevalence of Listeria spp. in Traditional Indian Dairy Products from Chennai Metropolis, Tamil Nadu. Procedia Food Sci. 6:230-234. Thongson C, Davidson PM, Mahakarnchanakul W, Vibulsresth P (2005). Antimicrobial Effect of Thai Spices against Listeria Monocytogenes and Salmonella Typhimurium DT104. J. Food Protect. 68(10):2054-2058. Tweten RK (2005). Cholesterol-dependent cytolysins, a family of versatile pore-forming toxins. Infect. Immun. 73:6199-6209. Weller D, Andrus A, Wiedmann M, den Bakker HC (2015). Listeria booriae sp. nov. and Listeria newyorkensis sp. nov., from food processing environments in the USA. Int. J. Syst. Evol. Microbiol. 65(1):286-292. Wong KY, Freitag NE (2004). Listeria monocytogenes invasion and intracellular growth. In: Lamont, R.J. (Ed.), Bacterial Invasion of Host Cells. Cambridge University Press, Cambridge. Wong W C, Pui C F, Tunung R, Cheah Y K, Nakaguchi Y, Nishibuchi M, Son R (2012). Prevalence of Listeria monocytogenes in frozen burger patties in Malaysia. Int Food Res J. 19(4):1751-1756. Xiaolong C, Yi W, Yan W, Changyun Y (2017). Isolation and characterization of Listeria monocytogenes from the black-headed gull feces in Kunming, China. J Infect Public Health. http://dx.doi.org/10.1016/j.jiph.2017.03.003 Zhu Q, Gooneratne R, Hussain M (2017) . Listeria monocytogenes in Fresh Produce: Outbreaks, Prevalence and Contamination Levels. Foods 6(3):21. doi:10.3390/foods60300211996-0808https://doi.org/https://pdfs.semanticscholar.org/1215/f7cfbc3501eb383634ae727f35e555c1e53f.pdfListeria monocytogenes is among the most important foodborne pathogens. It may enter foodprocessing environments through raw materials, handlers or equipment and may persist due to ineffective cleaning or sanitation. The bacterium can be isolated from both frozen vegetables and fresh food substances. This study aimed to estimate the prevalence of L. monocytogenes in spices and frozen vegetables and screen for some virulence factors and drug-resistance determinants of the isolated bacteria. First, conventional microbiological methods were used for the isolation and identification of bacteria. Next, the identity of isolated bacteria was confirmed by molecular techniques, and the virulence genes iap and hlyA were identified by real-time polymerase chain reaction (PCR). The hemolytic activity of the isolates was assessed by cultivation on sheep blood agar. Furthermore, the antimicrobial susceptibility of confirmed L. monocytogenes isolates was tested by the disk diffusion method against 10 antibiotics. Out of 331 vegetable samples, 47 isolates were confirmed to contain L. monocytogenes, whereas none of 40 spice samples tested positive. All isolates were positive for iap and hlyA genes. Susceptibility testing indicated that all isolates were sensitive to trimethoprim/ sulfamethoxazole, but only 36% were sensitive to penicillin G, while 100% and 70% showed intermediate resistance to chloramphenicol and erythromycin, respectively. All tested isolates were resistant to amoxicillin, gentamicin and norfloxacin; on the other hand, 90, 86 and 84% of the tested strains were resistant to ciprofloxacin, ceftazidime/clavulanic acid and amikacin, respectively. In summary, L. monocytogenes isolates disseminated in frozen vegetable samples from the Egyptian market were highly virulent, entirely multiple-drug resistant and were enriched in iron-containing vegetables. Since L. monocytogenes is primarily pathogenic to humans and causes a life-threatening disease, there is a potential infection risk for people who usually deal with frozen vegetables before cooking. Hence, surveillance to L. monocytogenes in frozen products, together with implementation of tight measures would be valuable in preventing listeriosis, and are highly recommendeden-USantibiotic resistance.virulence geneListeria monocytogenesArticlehttps://doi.org/