Host Ranges of Listeria -Specific Bacteriophages from the Turkey Processing Plant Environment in the United States

Abstract

Even though at least 400 Listeria phages have been isolated from various sources, limited information is available on phages from the food processing plant environment. Phages in the processing plant environment may play critical roles in determining the Listeria population that becomes established in the plant. In this study, we pursued the isolation of Listeria-specific phages from environmental samples from four turkey processing plants in the United States. These environmental samples were also utilized to isolate Listeria spp. Twelve phages were isolated and classified into three groups in terms of their host range. Of these, nine ( Listeria monocytogenes is an important food-borne pathogen responsible for listeriosis, an illness with severe symptoms and relatively high mortality rates (20 to 30%). Individuals at risk are primarily pregnant women and their fetuses, immunocompromised patients, and the elderly. Most cases of human listeriosis involve bacteria of serotypes 1/2a, 1/2b, and 4b. The food processing plant environment is of key importance for the contamination of ready-to-eat foods by L. monocytogenes (15,16). However, attributes of the bacteria that determine their distribution, prevalence, and persistence in the processing plant environment remain poorly characterized.The ability of L. monocytogenes to form biofilms and to resist disinfectants commonly employed for processing plant sanitation has been postulated to be an important determinant of the organism's ecology in the processing plant environment (16). Differences in ability to form biofilms and to tolerate disinfectants used in processing plants may contribute to the higher relative prevalence of certain serotypes. In several studies, strains of serotype 1/2a were significantly more frequently isolated from environmental samples of processing plants than were strains of serotype 4b (17,27,30,31). There is evidence that serotype 1/2a strains were more likely to form biofilms and to be resistant to the disinfectant benzalkonium chloride (BC) than were strains of serotype 4b (4,24,25).Another potentially important determinant of Listeria's ecology in the processing plant (and other) environments would be expected to be the susceptibility of the organisms to Listeria-specific bacteriophage (listeriaphage). The first listeriaphage report was published in 1945 (28), and to date, at least 400 phages have been isolated from various sources, including foods, sewage, silage, and lysogenic strains (21). The differential susceptibility of Listeria strains to selected phages has been utilized extensively as a strain-typing tool in epidemiological studies (22). Recent studies suggest the potential of phages as biological control agents for Listeria in foods and in the processing plants (13,18,19), and in 2006, the U.S. FDA approved the application of a listeriaphage mixture on the surface of ready-to-eat meat and poultry products (11). GRAS (generally regarded as safe) status has been granted to listeriaphage P100, isolated from a sewage effluent sampl...

Presencia de Listeria monocytogenes en alimentos listos para el consumo, procedentes de plazas de mercado y delicatessen de supermercados de cadena, Bogotá, D.C, 2002-2008

“…Es un microorganismo ambiental que tiene la facultad de adherirse a las superficies, formando biopelículas (20,30,32,35) para protegerse de la acción de los tratamientos antimicrobianos (20,30,35). En el ambiente de fábrica de producción de alimentos, tiene la oportunidad de contaminar en sus diferentes etapas, siendo esta vía la más frecuente para llegar al ser humano (2,5,12,30).…”

“…La listeriosis, cuyo agente etiológico es Listeria monocytogenes (2,4,5,(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), se sitúa entre las enfermedades transmitidas por alimentos de mayor relevancia en la salud pública, debido al impacto social y económico que tiene por la gravedad de su cuadro clínico (1,6,19,21,22).…”

Two Novel Type II Restriction-Modification Systems Occupying Genomically Equivalent Locations on the Chromosomes of Listeria monocytogenes Strains

“…For phage assays, we utilized Listeria phage 20422-1, isolated from the environment of a turkey processing facility (16). This phage was propagated in L. monocytogenes DP-L862 as described previously (16). The methylated phage derivatives 20422-1MJ2 and 20422-1MJ3 were obtained by propagating 20422-1 at least twice in strains J2479 and J3115, which harbor LmoJ2 and LmoJ3, respectively.…”

“…Phage infection assays. For phage assays, we utilized Listeria phage 20422-1, isolated from the environment of a turkey processing facility (16). This phage was propagated in L. monocytogenes DP-L862 as described previously (16).…”

“…The methylated phage derivatives 20422-1MJ2 and 20422-1MJ3 were obtained by propagating 20422-1 at least twice in strains J2479 and J3115, which harbor LmoJ2 and LmoJ3, respectively. Phage amplification and susceptibility assays were done as described previously (16). Efficiency of plaquing (EOP) was defined as the ratio of PFU per ml obtained from a specific strain to PFU/ml obtained with the reference strain, DP-L862.…”