Phage for Rapid Detection and Control of Bacterial Pathogens in Food

Rees, Catherine; Dodd, Christine E. R.

doi:10.1016/s0065-2164(06)59006-9

Cited by 65 publications

(34 citation statements)

References 74 publications

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“…Phages are widely distributed in the environment (12) and represent part of the natural microbiological flora of foods (27,54,55). Especially suitable for biocontrol purposes are virulent (strictly lytic) phages; they cannot integrate their genome into the bacterial chromosome to form lysogens and will always lyse and kill infected target cells.The current standing of the use of phages against undesired bacteria in food systems has been summarized previously (22,26,44). Briefly, phages were tested in foods contaminated with strains of Campylobacter (19,35), Escherichia coli (1, 41), Enterobacter (28), Pseudomonas (17, 23), Brochothrix (24), Salmonella (31,33,40,43,53), and Listeria (10,16,32,33,34).…”

mentioning

confidence: 99%

Virulent Bacteriophage for Efficient Biocontrol of Listeria monocytogenes in Ready-To-Eat Foods

Guenther

Huwyler

Richard

et al. 2009

Appl Environ Microbiol

389

272

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Food-borne Listeria monocytogenes is a serious threat to human health, and new strategies to combat this opportunistic pathogen in foods are needed. Bacteriophages are natural enemies of bacteria and are suitable candidates for the environmentally friendly biocontrol of these pathogens. In a comprehensive set of experiments, we have evaluated the virulent, broad-host-range phages A511 and P100 for control of L. monocytogenes strains Scott A (serovar 4b) and WSLC 1001 (serovar 1/2a) in different ready-to-eat (RTE) foods known to frequently carry the pathogen. Food samples were spiked with bacteria (1 ؋ 10 3 CFU/g), phage added thereafter (3 ؋ 10 6 to 3 ؋ 10 8 PFU/g), and samples stored at 6°C for 6 days. In liquid foods, such as chocolate milk and mozzarella cheese brine, bacterial counts rapidly dropped below the level of direct detection. On solid foods (hot dogs, sliced turkey meat, smoked salmon, seafood, sliced cabbage, and lettuce leaves), phages could reduce bacterial counts by up to 5 log units. Variation of the experimental conditions (extended storage over 13 days or storage at 20°C) yielded similar results. In general, the application of more phage particles (3 ؋ 10 8 PFU/g) was more effective than lower doses. The added phages retained most of their infectivity during storage in foods of animal origin, whereas plant material caused inactivation by more than 1 log 10 . In conclusion, our data demonstrate that virulent broad-host-range phages, such as A511 and P100, can be very effective for specific biocontrol of L. monocytogenes in contamination-sensitive RTE foods.Listeria monocytogenes is an opportunistic human pathogen, widely distributed in the environment and transmitted to humans and animals via contaminated foods (50). The organism is well adapted to very different environmental conditions encountered in foods; it tolerates high levels of salt content (10 to 20%), can grow at pH values below 6, with low oxygen, and at temperatures down to 1°C (48). L. monocytogenes causes listeriosis, a severe disease which may result in septicemia, meningitis, encephalitis, or loss of the fetus during pregnancy (52). Although listeriosis is comparatively rare compared to other food-borne infections, the high mortality rate of 15 to 40% is of great concern (49, 52). Cases of sporadic and epidemic listeriosis are increasing (4, 6, 11), and it has been estimated that about 2,000 hospitalizations and 500 deaths occur annually in the United States as a result of the consumption of Listeria in foods (39). Although many foods can serve as vehicles for this pathogen, Listeria was often isolated from ready-to-eat (RTE) foods, such as milk and cheeses, cold-cut meats, smoked fish, seafood, and vegetables (45). RTE foods have been implicated in most of the major listeriosis outbreaks in the last 30 years (13,18,20,21,42,(45)(46)(47). Of particular concern is the fact that they are consumed directly, without a final bactericidal processing step. Since the preservation methods applicable to minimally processed RTE foods of...

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confidence: 99%

Virulent Bacteriophage for Efficient Biocontrol of Listeria monocytogenes in Ready-To-Eat Foods

Guenther

Huwyler

Richard

et al. 2009

Appl Environ Microbiol

389

272

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“…In addition, there may be host inhibitory factors that can prevent phage replication and lysis but may not inhibit luxAB expression, such as the presence of a prophage in the cell, DNA restriction-modification, lysis resistant mutants, and even phage-specific inhibition genes (abortive infection) (7). Thus, it is possible that the reporter phage can have a detection range that is wider that the parental phage cell lysis host range (19,27). Our results indicate that the reporter phage did not transduce a bioluminescent signal to E. coli K-12 or E. coli B, but 1 of the 10 Y. enterocolitica strains (CDC 497-70) tested produced an attenuated bioluminescent signal ( Table 2).…”

Section: Discussionmentioning

confidence: 81%

“…A similar lysis assay using ␥ phage is FDA approved as a standard for the identification of B. anthracis isolates (1). In an effort to significantly reduce the time to detection and to enable detection in complex matrices such as food or clinical specimens, reporter phages are being developed as biodetectors of pathogenic bacteria (27). For example, reporter phages have been generated for E. coli O157:H7 and L. monocytogenes and have proven effective for the detection of bacteria in a range of diverse food matrices such as milk, ground beef, spinach, and soft cheese (4,22,23,25,28).…”

Section: Discussionmentioning

confidence: 99%

Diagnostic Bioluminescent Phage for Detection of Yersinia pestis

2009

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Yersinia pestis is the etiological agent of the plague. Because of the disease's inherent communicability, rapid clinical course, and high mortality, it is critical that an outbreak, whether it is natural or deliberate, be detected and diagnosed quickly. The objective of this research was to generate a recombinant luxAB ("light")-tagged reporter phage that can detect Y. pestis by rapidly and specifically conferring a bioluminescent signal response to these cells. The bacterial luxAB reporter genes were integrated into a noncoding region of the CDC plague-diagnostic phage A1122 by homologous recombination. The identity and fitness of the recombinant phage were assessed through PCR analysis and lysis assays and functionally verified by the ability to transduce a bioluminescent signal to recipient cells. The reporter phage conferred a bioluminescent phenotype to Y. pestis within 12 min of infection at 28°C. The signal response time and signal strength were dependent on the number of cells present. A positive signal was obtained from 10 2 cells within 60 min. A signal response was not detectable with Escherichia coli, although a weak signal (100-fold lower than that with Y. pestis) was obtained with 1 (of 10) Yersinia enterocolitica strains and 2 (of 10) Yersinia pseudotuberculosis strains at the restrictive temperature. Importantly, serum did not prevent the ability of the reporter phage to infect Y. pestis, nor did it significantly quench the resulting bioluminescent signal. Collectively, the results indicate that the reporter phage displays promise for the rapid and specific diagnostic detection of cultivated Y. pestis isolates or infected clinical specimens.

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“…The self-propagating capacity of lytic bacteriophages is also an advantage concerning the amount of inoculant to be added, decreasing in principle the processing costs. Phages have been shown to control the growth of pathogens such as L. monocytogenes, Salmonella and Campylobacter jejuni, as well as spoilage organisms in fruit, dairy products, poultry and red meats (Greer, 2005;Hudson et al, 2005;Rees and Dodd, 2006). Nevertheless, due to their high strain specificity, it is often necessary to apply complex phage mixtures, making the phage selection procedures rather complicated.…”

Section: Application Of Lytic Bacteriophagesmentioning

confidence: 99%