InTechOpen uses cookies to offer you the best online experience. By continuing to use our site, you agree to our Privacy Policy.

Medicine » Infectious Diseases » "Current Topics in Salmonella and Salmonellosis", book edited by Mihai Mares, ISBN 978-953-51-3066-6, Print ISBN 978-953-51-3065-9, Published: April 5, 2017 under CC BY 3.0 license. © The Author(s).

Chapter 5

Current and Emerging Innovations for Detection of Food-Borne Salmonella

By Wei Wu and Lingwen Zeng
DOI: 10.5772/67264

Article top


Overview of Bacteriological Analytical Manual (FDA-BAM) workflow for the detection, isolation, and subtyping of Salmonella. It takes 5 days for the detection and isolation of Salmonella, and a week more for subsequent confirmation and subtyping recent molecular methods, such as MS, WGS, and PCR/qPCR, may shorten the result time [36].
Figure 1. Overview of Bacteriological Analytical Manual (FDA-BAM) workflow for the detection, isolation, and subtyping of Salmonella. It takes 5 days for the detection and isolation of Salmonella, and a week more for subsequent confirmation and subtyping recent molecular methods, such as MS, WGS, and PCR/qPCR, may shorten the result time [36].

Current and Emerging Innovations for Detection of Food-Borne Salmonella

Wei Wu1 and Lingwen Zeng2
Show details


Salmonella is one of the leading causes of food-borne illnesses worldwide, and one of the main contributors to salmonellosis is the consumption of contaminated egg, poultry, pork, beef, and milk products. Since deleterious effects of Salmonella on public health and the economy continue to occur, improving safety of food products by early detection of food-borne pathogens would be considered an important component for limiting exposure to Salmonella contamination. Therefore, there is an ongoing need to develop more advanced detection methods that can identify Salmonella accurately and rapidly in foods before they reach consumers. In the past three decades, there have been increasing efforts toward developing and improving rapid pathogen detection and characterization methodologies for application to food products. In this chapter, we discuss molecular methods for detection, identification, and genetic characterization of Salmonella in food. In addition, the advantages and disadvantages of the established and emerging rapid detection methods are addressed here. The methods with potential application to the industry are highlighted in this chapter.

Keywords: Salmonella, food-borne pathogens, rapid detection, molecular methods, aptamer, antibody

1. Introduction

Food-borne disease is one of the major public health problems for the food industry, especially in developing countries [1]. Failure to detect food-borne pathogens may lead to a dreadful effect. The World Health Organization (WHO) reported that in 2010 alone 1.8 million people died from diarrheal diseases, a great proportion of these cases can be attributed to contaminated food and drinking water [2]. The Centers for Disease Control and Prevention (CDC) have estimated that 48 million cases of food-borne illnesses occur in the United States (US) annually, approximately 128,000 cases require hospitalization, and 3,000 cases result in death [3]. The CDC reported that viruses, bacteria, and parasites are major causative agents for food-borne illnesses. Among these, bacterial agents including Salmonella, Listeria monocytogenes, and Escherichia coli are associated with these cases, being responsible for most of the hospitalizations (63.9%) and deaths (63.7%). Especially, Salmonella species were considered as the leading cause for these more severe cases resulting in 35% of the hospitalizations and 28% of the deaths [4]. Salmonella, belonging to the family of Enterobacteriaceae, are Gram-negative, facultative anaerobic, and nonspore-forming bacilli. The genus Salmonella is consisted of two species, enterica and bongori, with six subspecies of S. enterica. The different serotypes are divided based on the specific surface molecules O-antigen (O-Ag) and H-antigen (H-Ag) [5]. Collectively, there are over 2500 serotypes of salmonellae capable of causing disease in humans. Most serotypes of the salmonellae could cause gastroenteritis, while a few serotypes of salmonellae would cause severe disease enteric fever, which was characterized as the onset of high fever accompanied with abdominal pain and malaise without diarrhea or vomiting [6]. Commonly, salmonellosis is self-limiting, resolving in about a week. Occasionally, however, the infection becomes systemic, a much more severe disease requiring antibiotic interventions [7]. The dose of Salmonella causing infection in humans indicated a wide range for the number of cells required to cause disease, ranged from 105 to 1010 cells. In contrast, enumeration of food products indicate much lower numbers of organisms, as low as ten cells, were present to cause illness [8, 9].

Most human salmonellosis cases are associated with consumption of contaminated egg, poultry, pork, beef, and milk products, which are considered one of the most important reservoirs from which Salmonella is passed through the food chain and ultimately transmitted to humans [10]. With increasing consumption of these food products, the number of associated salmonellosis continues to be a public health issue all around the world. It is estimated that 95% of Salmonella infections are due to the consumption of contaminated foodstuffs, which suggest that salmonellae may be present at low levels in food but still capable of causing a significant number of infections [11]. Yearly, in the United States, it is estimated that Salmonella is responsible for over a million illnesses, 19,000 hospitalizations, and almost 400 deaths. This is in part due to their marked ability to persist in a wide range of varying environmental conditions [12]. For example, Salmonella strains can grow in foods stored at low (2–4°C) and high (54°C) temperatures [13].

Since Salmonella is a major causative agent for food-associated food-borne illnesses, improving safety of poultry products by early detection of food-borne pathogens would be considered an important component for limiting exposure to Salmonella contamination. In order to safeguard the food supply and ensure public health, it is essential to establish rapid, reliable, and sensitive method for Salmonella detection. In the past two decades, there has been a thrust to develop rapid methods for identifying and detecting Salmonella specifically in foodstuffs [1417]. This chapter will focus on the current culture-dependent and culture-independent methods for the rapid, accurate detection, identification, and subtyping of salmonellae in foodstuffs.

2. Methodologies for detection of Salmonella

2.1. Culture-dependent methods

Current testing of food samples for the presence of salmonellae can be divided into three steps: (1) detection of pathogen by plate culture, (2) identification of the isolate and its specific serovar designation, and (3) subtyping of the isolate for association with salmonellosis [18, 19]. These methods rely on traditional bacterial culture procedures that apply serial enrichments with increasing selectivity culminating in the isolation of Salmonella on selective differential agar plates (Figure 1). It always takes up to 5 days to obtain a presumptive positive result. Then traditional biochemical testing of nutrient utilization medium is needed for confirmation, another few days to complete [20]. Although innovative technologies have been applied to subtype salmonellae isolation, at least 24 h is needed for a confirmation of Salmonella in multiple analytes. DNA fingerprinting techniques are based on DNA size differences on an agarose gel. The digested genomic DNA of target bacteria is separated on an agarose gel and then hybridized with complementary sequences for identifying the banding pattern. A database of fingerprint species, serovar, and strain identifications is used for comparison [2123]. The fingerprinting methods include pulsed-field gel electrophoresis (PFGE), ribotyping, and intergenic sequence (IGS) ribotyping. The use of PFGE has greatly increased the ability of track and trace back illness clusters and outbreaks. However, PFGE still requires a pure isolate and a minimum of 3 days to complete [24, 25].


Figure 1.

Overview of Bacteriological Analytical Manual (FDA-BAM) workflow for the detection, isolation, and subtyping of Salmonella. It takes 5 days for the detection and isolation of Salmonella, and a week more for subsequent confirmation and subtyping recent molecular methods, such as MS, WGS, and PCR/qPCR, may shorten the result time [36].

Due to its sensitivity, with a limit of detection of 1 cfu, this analytical schema is considered as the “gold standard” of regulatory agencies (Figure 1). The disadvantages of this method are as follows. First, it is time-consuming, taking at least a week for isolation and few more days for serotyping and subtyping. The long time frame hampers its application in many food commodities, especially fresh products, before they are consumed or on hold in warehouses while awaiting test results before they spoil. Second, the operation is tedious; the amount of media and numerous plates are required for each sample. The procedures are labor-consuming and necessitate large areas of space, particularly in many sample detections. Finally, the complex ingredients in foodstuffs, such as indigenous microbiota and antimicrobials, make it notably difficult for traditional microbiological methods [11, 2629].

2.2. Culture-independent methods

Recent advances in technology have made the detection of food-borne pathogens more rapid and convenient, while achieving improved sensitivity and specificity in comparison to conventional methods. These methods employing newer technologies are generally referred as “rapid methods,” which include nucleic acid-based or antibody-based assays that are modified or improved compared to conventional methods [3035]. These rapid detection methods can be of high value to the food industry by providing several key advantages such as speed, specificity, sensitivity, cost-efficiency, and labor efficiency.

2.2.1. Polymerase chain reaction (PCR)

The largest advance toward faster detection of salmonellae has been in the realm of molecular biology, where polymerase chain reaction (PCR) and quantitative PCR (qPCR) are predominantly being applied as the methods of choice for the detection. Different protocols targeting different specific genes or gene regions specific to salmonellae have been published. Numerous studies have been conducted to detect and characterize Salmonella in poultry, poultry products, and feeds using PCR assays to target selected antibiotic resistance or virulence genes along with genus-, species-, and serotype-specific genes [16, 3740].

Over the past years, PCR-based methods have advanced to provide high sensitivity for Salmonella detection and identification. Aabo et al. used PCR assay for Salmonella detection in minced meat and compared this method to a culture-based methodology. The sensitivity of the PCR was 89% (85 out of 96 samples), which was much higher than that of the culture method (50%, 48 out of 96 samples) [41]. Rychlik et al. established nested PCR with high sensitivity, which has a higher annealing temperature than the primers used in the first PCR, to detect Salmonella in chicken feces [42].

As we all know, the quality and quantity of target DNA, PCR template, are important factors during the design of a PCR assay. Although well-designed PCR primer and good PCR template can bring high specificity of the target detection, it is still not sufficient to overcome the side effects of PCR inhibitors in samples, such as denatured proteins, organic chemicals, and sucrose. Moreover, the presence of DNA and cells other than those from the targeted organism can affect the efficiency of the PCR methods. To overcome this, an enrichment step is commonly performed to enhance assay sensitivity by ensuring the detection of viable pathogens before PCR reaction. Ferretti et al. reported that PCR with a 6 h nonselective enrichment could detect various Salmonella serotypes in salami stuffs as low as 1 cfu in 100 ml of food homogenate [43, 44]. Myint et al. reported a PCR method for Salmonella detection in contaminated poultry tissue samples, and false negative results were obtained without enrichment. However, a positive rate of 90% was observed after enrichment. Generally, culture enrichment is recommended in order to distinguish live cells from dead cells before PCR [45]. Maciorowski et al. investigated different enrichment times to detect indigenous Salmonella in poultry dietary samples using PCR. It was found that it could not be detectable for Salmonella with 7 h enrichment, and the sensitivity for detection was 25 and 50% with 13 h enrichment and 24 h enrichment, respectively [46].

Improvements have also been made on the basic PCR technology as well. In particular, two primary PCR-based methods have emerged over the past several years, such as multiplex PCR and real-time quantitative PCR [47, 48]. The current status of the optimization and development of these PCR applications is summarized in the following.

Multiplex PCR is a modified PCR method that allows for multiple sequence targets to be simultaneously detected within a single reaction. This method has proven useful for the rapid identification of multiple pathogens simultaneously in a given sample. Generally, multiplex PCR amplifies the target samples using multiple primers in a reaction, which can detect and identify several target sequences in Salmonella. Sharma employed a multiplex fluorogenic PCR assay for simultaneous detection of Salmonella and E. coli O157:H7, which was capable of detecting as low as 10 cfu/g in meat [49]. Similarly, Kawasaki detected multiple Salmonella serotypes, L. monocytogenes, and E. coli O157:H7 simultaneously in enriched meat samples using multiplex PCR [48]. Cortez et al. identified Salmonella from chicken abattoirs by multiplex PCR. In this paper, 29 out of 288 (~10%) samples were found to be positive for Salmonella spp., and 16 (~5.6%) and 7 (~2.4%) samples were characterized as Salmonella Typhimurium and Salmonella enteritidis, respectively [50]. Kim differentiated the 30 most prevalent Salmonella serotypes in the United States by using two five-plex PCR assays. In this study, primer pairs targeting six genetic loci from S. Typhimurium and four from S. Typhi were designed to evaluate various Salmonella serotypes [51]. More recently, Salemis et al. also established two five-plex assays for the detection of the most common Salmonella in Tunisia as well [52]. Although multiplex PCR can simultaneously detect several targets, the primary difficulties are uncommitted, in which reaction conditions are needed optimized as high amounts of DNA in the reaction mixture compared to single PCR-based assays. The complex conditions and ingredients in the reaction still increase the difficulty in discrimination between prominent PCR product sizes on traditional agarose gel electrophoresis. In practice, cross-reactivity of primer pairs and sensitivity limitations associated with the procedure make it still quite challenging to routinely use multiplex PCR for reliable simultaneous Salmonella serovar detection [53].

With the appearance of fluorescence technology that endows increased sensitivity (e.g., intercalating dyes such as SYBR Green or labeled probes), the limitations of conventional PCR can be overcome, such as the errors associated with end-point analyses and lack of quantification. The “real-time” aspect of real-time PCR, also referred to as qPCR, technology is linked to its ability to label and cumulatively quantify the generated PCR products at each cycle throughout the ongoing amplification process. The qPCR has been widely used to quantify Salmonella [5456]. Daum screened nine foodstuffs associated with a Salmonella outbreak in Texas using qPCR. It was reported that only one food item was positive for Salmonella [57]. Wang et al. reported a qPCR method to detect Salmonella in raw sausage meat with detection limit of 4 cfu/g [58]. He also used this method to quantify Salmonella detection limits of 2.5 cfu/25 g for salmon and minced meat, 5 cfu/25 g of chicken meat, and 5 cfu/25 ml for raw milk, respectively [59]. Malorny et al. reported a duplex qPCR assay to detect S. enteritidis in whole chicken carcass rinses and eggs, with a detection limit of 3 cfu/50 ml of chicken carcass rinses and 3 cfu/10 ml of homogenized egg content [60]. Bohaychuk used qPCR for Salmonella detection in poultry cecal contents and carcasses with reported sensitivities ranging from 97 to 100% for various matrices [61]. Although qPCR is an effective tool to detect Salmonella with high sensitivity and specificity, it does have several limitations, which are listed in Table 1.

Culture-dependent methods—Accurate—Labor and time cost
Single and multiplex PCR—More rapid than culture-based methods (<24 h vs. 5 ~ 7 days)
—High specificity and sensitivity
—Multiplex PCR (several pathogens at a time)
—Labor saving
—Multidetection of several Salmonella serotypes (5 ~ 6) in one reaction
—Costs more than culture-based methods and ELISA
—Difficulty in distinguishing live and dead cells
—Technically can be challenging (optimized PCR condition)
—Enrichment to detect viable cells
—Requires post-PCR processing of products (electrophoresis)
—PCR inhibitors
qPCR—Not influenced by nonspecific amplification; amplification can be monitored at real time
—No post-PCR processing of products (gel electrophoresis)
—Rapid cycling (25 min)
—Confirmation of specific amplification by melting curve
—Specific, sensitive, and reproducible
—Difficulty in multiplex assay
—Need skilled person and support
—High equipment cost
—mRNA lability
—Possibility of cross contamination
Antibody-based method—More rapid than culture-based methods (2 days vs. 5 ~ 7 days)
—Can be automated to reduce assay time and manual labor input
—Able to handle large numbers of samples
—More specific than cultural methods
—Not high sensitivity
—Difficult to multidetect
—False-negative results
—Difficulty to differentiate damaged or stressed cells
—Need to pre-enrichment
—High cross-reactivity with close antigens in bacteria
Aptamer-based method—Inexpensive, stable, and can be chemically synthesized than antibody
—Time saving (2 h vs. 5 ~ 7 days of culture-based methods)
—Automated to reduce manual labor input
—Large numbers of sample detection at one time
—Higher specificity than cultural methods
—High false-positive results
—Difficulty in detecting damaged or stressed cells
—Pre-enrichment for production of cell surface antigens
—Possibility of cross contamination

Table 1.

Advantages and disadvantages of detection methods.

2.2.2. Enzyme-linked immunosorbent assay (ELISA)

Enzyme-linked immunosorbent assay (ELISA)-based approaches are the most prevalent antibody-based assay for pathogen detection in foods [62]. This immunological approach has been used to detect Salmonella in poultry production (poultry feed, feces, litter, carcass rinsing, and water samples) and has provided a better sensitivity and shorter time frame than that of culture-based methods [46]. Improvements by combination with other advanced technologies have been made to the basic ELISA method for Salmonella detection. For example, incorporation of monoclonal antibodies can improve the sensitivity of the assay, and it can quantify Salmonella among poultry probiotic bacteria such as Veillonella [63]. In this study, the detection limit for S. Typhimurium was determined to be 5.5 × 104 cells/ml in pure culture. Dill combined monoclonal and polyclonal antibodies and a commercial filtering system to detect S. Typhimurium cells in a chicken rinsate, with detection limit of fewer than 100 S. Typhimurium cells [64]. As the advantages of ELISA methods for Salmonella detection in foods and animal feeds, they are now widely used for detection of Salmonella in animal-producing foods [65]. The comparison of ELISA methods with culture-based methods is performed and listed in Table 1.

2.2.3. Aptamer-based detection assay

Besides antibodies, other biomolecules have been investigated to selectively capture and enrich Salmonella from cultures, among which aptamer is the most prevalent one [66]. Aptamers are single-stranded oligonucleotides, DNA, or RNA that can fold into unique 3D structures based on their primary nucleotide sequence, rendering them capable of binding to specific ligands, like antibody interacting with an antigen [67]. Aptamers offer some advantages over antibodies in that they are relatively inexpensive to synthesize and they provide more batch-to-batch consistency [68]. However, few studies have reported their specific use in detecting S. Typhimurium from river water and fecal samples [66, 69]. Bacteriophages have also been explored as a means to capture Salmonella cells. Phages may offer some advantages over antibodies given their inherent specificity for host cells, their ease of production in bacteria versus animals or eukaryotic cell culture, and their relative stability in harsh conditions such as pH and temperature extremes [70].

Relative to culture-independent detection, researchers have focused on methods to concentrate whole cells within the sample before the pre-enrichment step. The enriched whole Salmonella allows for direct detection from food and environmental samples. The enrichment steps mainly rely on filtering liquids, rinsates, or mechanically disintegrated (i.e., blended or stomached) samples. Therefore, this approach has been widely used in large volumes of water, but the testing of food samples was problematic due to the food particles difficult to go through filter membranes [71]. To overcome this problem, endopeptidases have been added to apply in food samples. These degrade the small, soluble proteins and peptides so that they are unable to clog the filter and pass through with the permeate. The United States has awarded the method with grant prize. The Food and Drug Administration also recommends the method for food safety guard, (, which signified its potential to greatly enhance the detection of Salmonella directly from foods.

2.3. Conclusion

In summary, the mentioned methods here have utility advantages for Salmonella detection in the food safety sector. It is important to emphasize that none of the methods will be recommended or even suited for every situation in detecting all food varieties for Salmonella. Application to specific food samples will be dictated by method performance. As noted previously, the performance of these methods depends on several factors, such as matrix-driven effects, general specificity and sensitivity, and their technical complexity. Meanwhile, other extrinsic factors would affect the performance, including user skill set and technical prowess, cost of the equipment, and cost per sample. Hence, the systematic validation to evaluate the methods should be considered according to its specific utility and application across the food supply.

In order to meet the current requirement of rapid detection, it is clear that several approaches have emerged including PCR-based, antibody-based, aptamer-based, and other approaches encompassing those stemming from the current genomic era. A clear character of method development direction is moving toward greater automation, cost-saving, and time-saving network integration. It is important to mention that outputs from one approach would serve to strengthen directly or tangentially other approaches. At last, it seems that a suite of tools is emerging for the food safety microbiologist, each with its specific advantages and disadvantages but all with the ability to rapidly and accurately detect Salmonella in certain cases and early in its contamination of the human and veterinary food supply.


1 - Ameme DK, Abdulai M, Adjei EY, Afari EA, Nyarko KM, Asante D, Kye-Duodu G, Abbas M, Sackey S and Wurapa F. Foodborne disease outbreak in a resource-limited setting: a tale of missed opportunities and implications for response. Pan Afr Med J 2016; 23: 69.
2 - Havelaar AH, Kirk MD, Torgerson PR, Gibb HJ, Hald T, Lake RJ, Praet N, Bellinger DC, de Silva NR, Gargouri N, Speybroeck N, Cawthorne A, Mathers C, Stein C, Angulo FJ and Devleesschauwer B. World Health Organization global estimates and regional comparisons of the burden of foodborne disease in 2010. PLoS Med 2015; 12: e1001923.
3 - Talan DA and Moran GJ. Update on emerging infections: news from the Centers for Disease Control and Prevention. Surveillance for foodborne disease outbreaks – United States, 2006. Ann Emerg Med 2010; 55: 47-49.
4 - Henao OL, Scallan E, Mahon B and Hoekstra RM. Methods for monitoring trends in the incidence of foodborne diseases: foodborne diseases active surveillance network 1996–2008. Foodborne Pathog Dis 2010; 7: 1421-1426.
5 - McQuiston JR, Herrera-Leon S, Wertheim BC, Doyle J, Fields PI, Tauxe RV and Logsdon JM, Jr. Molecular phylogeny of the salmonellae: relationships among Salmonella species and subspecies determined from four housekeeping genes and evidence of lateral gene transfer events. J Bacteriol 2008; 190: 7060-7067.
6 - Weill FX, Tran HH, Roumagnac P, Fabre L, Minh NB, Stavnes TL, Lassen J, Bjune G, Grimont PA and Guerin PJ. Clonal reconquest of antibiotic-susceptible Salmonella enterica serotype Typhi in Son La Province, Vietnam. Am J Trop Med Hyg 2007; 76: 1174-1181.
7 - Kubota K, Kasuga F, Iwasaki E, Inagaki S, Sakurai Y, Komatsu M, Toyofuku H, Angulo FJ, Scallan E and Morikawa K. Estimating the burden of acute gastroenteritis and foodborne illness caused by Campylobacter, Salmonella, and Vibrio parahaemolyticus by using population-based telephone survey data, Miyagi Prefecture, Japan, 2005 to 2006. J Food Prot 2011; 74: 1592-1598.
8 - Tadesse G. Prevalence of human Salmonellosis in Ethiopia: a systematic review and meta-analysis. BMC Infect Dis 2014; 14: 88.
9 - Blaser MJ and Newman LS. A review of human salmonellosis: I. Infective dose. Rev Infect Dis 1982; 4: 1096-1106.
10 - Painter JA, Hoekstra RM, Ayers T, Tauxe RV, Braden CR, Angulo FJ and Griffin PM. Attribution of foodborne illnesses, hospitalizations, and deaths to food commodities by using outbreak data, United States, 1998–2008. Emerg Infect Dis 2013; 19: 407-415.
11 - Bell RL, Zheng J, Burrows E, Allard S, Wang CY, Keys CE, Melka DC, Strain E, Luo Y, Allard MW, Rideout S and Brown EW. Ecological prevalence, genetic diversity, and epidemiological aspects of Salmonella isolated from tomato agricultural regions of the Virginia Eastern Shore. Front Microbiol 2015; 6: 415.
12 - Scallan E, Griffin PM, Angulo FJ, Tauxe RV and Hoekstra RM. Foodborne illness acquired in the United States – unspecified agents. Emerg Infect Dis 2011; 17: 16-22.
13 - Balamurugan S and Dugan ME. Growth temperature associated protein expression and membrane fatty acid composition profiles of Salmonella enterica serovar Typhimurium. J Basic Microbiol 2010; 50: 507-518.
14 - Park SH, Aydin M, Khatiwara A, Dolan MC, Gilmore DF, Bouldin JL, Ahn S and Ricke SC. Current and emerging technologies for rapid detection and characterization of Salmonella in poultry and poultry products. Food Microbiol 2014; 38: 250-262.
15 - Srisawat M and Panbangred W. Efficient and specific detection of Salmonella in food samples using a stn-based loop-mediated isothermal amplification method. Biomed Res Int 2015; 2015: 356401.
16 - Jenikova G, Pazlarova J and Demnerova K. Detection of Salmonella in food samples by the combination of immunomagnetic separation and PCR assay. Int Microbiol 2000; 3: 225-229.
17 - Bolton FJ, Fritz E, Poynton S and Jensen T. Rapid enzyme-linked immunoassay for detection of Salmonella in food and feed products: performance testing program. J AOAC Int 2000; 83: 299-303.
18 - Belete T, Crowley E, Bird P, Gensic J and Wallace FM. A comparison of the BAX system method to the U.S. Food and Drug Administration's Bacteriological Analytical Manual and International Organization for Standardization reference methods for the detection of Salmonella in a variety of soy ingredients. J Food Prot 2014; 77: 1778-1783.
19 - Zhang G, Thau E, Brown EW and Hammack TS. Comparison of a novel strategy for the detection and isolation of Salmonella in shell eggs with the Food and Drug Administration Bacteriological Analytical Manual method. Poult Sci 2013; 92: 3266-3274.
20 - Andrews JR, Prajapati KG, Eypper E, Shrestha P, Shakya M, Pathak KR, Joshi N, Tiwari P, Risal M, Koirala S, Karkey A, Dongol S, Wen S, Smith AB, Maru D, Basnyat B, Baker S, Farrar J, Ryan ET, Hohmann E and Arjyal A. Evaluation of an electricity-free, culture-based approach for detecting typhoidal Salmonella bacteremia during enteric fever in a high burden, resource-limited setting. PLoS Negl Trop Dis 2013; 7: e2292.
21 - Murase T, Nagato M, Shirota K, Katoh H and Otsuki K. Pulsed-field gel electrophoresis-based subtyping of DNA degradation-sensitive Salmonella enterica subsp. enterica serovar Livingstone and serovar Cerro isolates obtained from a chicken layer farm. Vet Microbiol 2004; 99: 139-143.
22 - Fenwick SG, Duignan PJ, Nicol CM, Leyland MJ and Hunter JE. A comparison of Salmonella serotypes isolated from New Zealand sea lions and feral pigs on the Auckland Islands by pulsed-field gel electrophoresis. J Wildl Dis 2004; 40: 566-570.
23 - Guard J, Sanchez-Ingunza R, Morales C, Stewart T, Liljebjelke K, Van Kessel J, Ingram K, Jones D, Jackson C, Fedorka-Cray P, Frye J, Gast R and Hinton A, Jr. Comparison of dkgB-linked intergenic sequence ribotyping to DNA microarray hybridization for assigning serotype to Salmonella enterica. FEMS Microbiol Lett 2012; 337: 61-72.
24 - Rivoal K, Protais J, Queguiner S, Boscher E, Chidaine B, Rose V, Gautier M, Baron F, Grosset N, Ermel G and Salvat G. Use of pulsed-field gel electrophoresis to characterize the heterogeneity and clonality of Salmonella serotype Enteritidis, Typhimurium and Infantis isolates obtained from whole liquid eggs. Int J Food Microbiol 2009; 129: 180-186.
25 - Xi M, Zheng J, Zhao S, Brown EW and Meng J. An enhanced discriminatory pulsed-field gel electrophoresis scheme for subtyping Salmonella serotypes Heidelberg, Kentucky, SaintPaul, and Hadar. J Food Prot 2008; 71: 2067-2072.
26 - Singer RS, Mayer AE, Hanson TE and Isaacson RE. Do microbial interactions and cultivation media decrease the accuracy of Salmonella surveillance systems and outbreak investigations? J Food Prot 2009; 72: 707-713.
27 - Kim SY, Kang DH, Kim JK, Ha YG, Hwang JY, Kim T and Lee SH. Antimicrobial activity of plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes on fresh lettuce. J Food Sci 2011; 76: M41-46.
28 - Gorski L. Selective enrichment media bias the types of Salmonella enterica strains isolated from mixed strain cultures and complex enrichment broths. PLoS One 2012; 7: e34722.
29 - Pettengill JB, McAvoy E, White JR, Allard M, Brown E and Ottesen A. Using metagenomic analyses to estimate the consequences of enrichment bias for pathogen detection. BMC Res Notes 2012; 5: 378.
30 - Siddique RA, Saxena M and Lakhchaura BD. PCR based rapid detection of Salmonella from poultry samples. Indian J Public Health 2009; 53: 226-228.
31 - McCarthy N, Reen FJ, Buckley JF, Frye JG, Boyd EF and Gilroy D. Sensitive and rapid molecular detection assays for Salmonella enterica serovars Typhimurium and Heidelberg. J Food Prot 2009; 72: 2350-2357.
32 - Chai Y, Li S, Horikawa S, Park MK, Vodyanoy V and Chin BA. Rapid and sensitive detection of Salmonella Typhimurium on eggshells by using wireless biosensors. J Food Prot 2012; 75: 631-636.
33 - Preechakasedkit P, Pinwattana K, Dungchai W, Siangproh W, Chaicumpa W, Tongtawe P and Chailapakul O. Development of a one-step immunochromatographic strip test using gold nanoparticles for the rapid detection of Salmonella Typhi in human serum. Biosens Bioelectron 2012; 31: 562-566.
34 - Yukawa S, Tamura Y, Tanaka K and Uchida I. Rapid detection of Salmonella enterica serovar Typhimurium DT104 strains by the polymerase chain reaction. Acta Vet Scand 2015; 57: 59.
35 - Sun Y, Quyen TL, Hung TQ, Chin WH, Wolff A and Bang DD. A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples. Lab Chip 2015; 15: 1898-1904.
36 - Jacobson AP, Gill VS, Irvin KA, Wang H and Hammack TS. Evaluation of methods to prepare samples of leafy green vegetables for preenrichment with the Bacteriological Analytical Manual Salmonella culture method. J Food Prot 2012; 75: 400-404.
37 - Murgia M, Rubino S, Wain J, Gaind R and Paglietti B. A novel broadly applicable PCR-RFLP method for rapid identification and subtyping of H58 Salmonella Typhi. J Microbiol Methods 2016; 127: 219-223.
38 - Wuyts V, Mattheus W, Roosens NH, Marchal K, Bertrand S and De Keersmaecker SC. A multiplex oligonucleotide ligation-PCR as a complementary tool for subtyping of Salmonella Typhimurium. Appl Microbiol Biotechnol 2015; 99: 8137-8149.
39 - Ogunremi D, Kelly H, Dupras AA, Belanger S and Devenish J. Development of a new molecular subtyping tool for Salmonella enterica serovar Enteritidis based on single nucleotide polymorphism genotyping using PCR. J Clin Microbiol 2014; 52: 4275-4285.
40 - Baquar N, Threlfall EJ, Rowe B and Stanley J. Molecular subtyping within a single Salmonella Typhimurium phage type, DT204c, with a PCR-generated probe for IS200. FEMS Microbiol Lett 1993; 112: 217-221.
41 - Aabo S, Andersen JK and Olsen JE. Research note: detection of Salmonella in minced meat by the polymerase chain reaction method. Lett Appl Microbiol 1995; 21: 180-182.
42 - Rychlik I, van Kesteren L, Cardova L, Svestkova A, Martinkova R and Sisak F. Rapid detection of Salmonella in field samples by nested polymerase chain reaction. Lett Appl Microbiol 1999; 29: 269-272.
43 - Ferretti R, Mannazzu I, Cocolin L, Comi G and Clementi F. Twelve-hour PCR-based method for detection of Salmonella spp. in food. Appl Environ Microbiol 2001; 67: 977-978.
44 - Soumet C, Ermel G, Fach P and Colin P. Evaluation of different DNA extraction procedures for the detection of Salmonella from chicken products by polymerase chain reaction. Lett Appl Microbiol 1994; 19: 294-298.
45 - Myint MS, Johnson YJ, Tablante NL and Heckert RA. The effect of pre-enrichment protocol on the sensitivity and specificity of PCR for detection of naturally contaminated Salmonella in raw poultry compared to conventional culture. Food Microbiol 2006; 23: 599-604.
46 - Maciorowski KG, Herrera P, Jones FT, Pillai SD and Ricke SC. Cultural and immunological detection methods for Salmonella spp. in animal feeds – a review. Vet Res Commun 2006; 30: 127-137.
47 - Yan H, Nguyen TA, Phan TG, Okitsu S, Li Y and Ushijima H. Development of RT-multiplex PCR assay for detection of adenovirus and group A and C rotaviruses in diarrheal fecal specimens from children in China. Kansenshogaku Zasshi 2004; 78: 699-709.
48 - Kawasaki S, Horikoshi N, Okada Y, Takeshita K, Sameshima T and Kawamoto S. Multiplex PCR for simultaneous detection of Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7 in meat samples. J Food Prot 2005; 68: 551-556.
49 - Sharma VK and Carlson SA. Simultaneous detection of Salmonella strains and Escherichia coli O157:H7 with fluorogenic PCR and single-enrichment-broth culture. Appl Environ Microbiol 2000; 66: 5472-5476.
50 - Cortez AL, Carvalho AC, Ikuno AA, Burger KP and Vidal-Martins AM. Identification of Salmonella spp. isolates from chicken abattoirs by multiplex-PCR. Res Vet Sci 2006; 81: 340-344.
51 - Kim S, Frye JG, Hu J, Fedorka-Cray PJ, Gautom R and Boyle DS. Multiplex PCR-based method for identification of common clinical serotypes of Salmonella enterica subsp. enterica. J Clin Microbiol 2006; 44: 3608-3615.
52 - Salemis NS. Salmonella pancolitis with acute abdomen. CT findings and review literature. Trop Gastroenterol 2010; 31: 49-51.
53 - Hyeon JY, Park C, Choi IS, Holt PS and Seo KH. Development of multiplex real-time PCR with Internal amplification control for simultaneous detection of Salmonella and Cronobacter in powdered infant formula. Int J Food Microbiol 2010; 144: 177-181.
54 - Barbau-Piednoir E, Bertrand S, Mahillon J, Roosens NH and Botteldoorn N. SYBR(R)Green qPCR Salmonella detection system allowing discrimination at the genus, species and subspecies levels. Appl Microbiol Biotechnol 2013; 97: 9811-9824.
55 - Sharbati S, Sharbati J, Hoeke L, Bohmer M and Einspanier R. Quantification and accurate normalisation of small RNAs through new custom RT-qPCR arrays demonstrates Salmonella-induced microRNAs in human monocytes. BMC Genomics 2012; 13: 23.
56 - Novinscak A, Surette C and Filion M. Quantification of Salmonella spp. in composted biosolids using a TaqMan qPCR assay. J Microbiol Methods 2007; 70: 119-126.
57 - Daum LT, Barnes WJ, McAvin JC, Neidert MS, Cooper LA, Huff WB, Gaul L, Riggins WS, Morris S, Salmen A and Lohman KL. Real-time PCR detection of Salmonella in suspect foods from a gastroenteritis outbreak in kerr county, Texas. J Clin Microbiol 2002; 40: 3050-3052.
58 - Wang L, Li Y and Mustaphai A. Rapid and simultaneous quantitation of Escherichia coli 0157:H7, Salmonella, and Shigella in ground beef by multiplex real-time PCR and immunomagnetic separation. J Food Prot 2007; 70: 1366-1372.
59 - Hein I, Flekna G, Krassnig M and Wagner M. Real-time PCR for the detection of Salmonella spp. in food: an alternative approach to a conventional PCR system suggested by the FOOD-PCR project. J Microbiol Methods 2006; 66: 538-547.
60 - Malorny B, Bunge C and Helmuth R. A real-time PCR for the detection of Salmonella Enteritidis in poultry meat and consumption eggs. J Microbiol Methods 2007; 70: 245-251.
61 - Bohaychuk VM, Gensler GE, McFall ME, King RK and Renter DG. A real-time PCR assay for the detection of Salmonella in a wide variety of food and food-animal matricest. J Food Prot 2007; 70: 1080-1087.
62 - Mandal TK and Parvin N. Rapid detection of bacteria by carbon quantum dots. J Biomed Nanotechnol 2011; 7: 846-848.
63 - Durant JA, Young CR, Nisbet DJ, Stanker LH and Ricke SC. Detection and quantification of poultry probiotic bacteria in mixed culture using monoclonal antibodies in an enzyme-linked immunosorbent assay. Int J Food Microbiol 1997; 38: 181-189.
64 - Dill K, Stanker LH and Young CR. Detection of Salmonella in poultry using a silicon chip-based biosensor. J Biochem Biophys Methods 1999; 41: 61-67.
65 - Hoorfar J. Rapid detection, characterization, and enumeration of foodborne pathogens. APMIS Suppl 2011; 133: 1-24.
66 - Jyoti A, Vajpayee P, Singh G, Patel CB, Gupta KC and Shanker R. Identification of environmental reservoirs of nontyphoidal salmonellosis: aptamer-assisted bioconcentration and subsequent detection of Salmonella Typhimurium by quantitative polymerase chain reaction. Environ Sci Technol 2011; 45: 8996-9002.
67 - Ozalp VC, Bayramoglu G, Erdem Z and Arica MY. Pathogen detection in complex samples by quartz crystal microbalance sensor coupled to aptamer functionalized core-shell type magnetic separation. Anal Chim Acta 2015; 853: 533-540.
68 - Bruno JG, Richarte AM, Phillips T, Savage AA, Sivils JC, Greis A and Mayo MW. Development of a fluorescent enzyme-linked DNA aptamer-magnetic bead sandwich assay and portable fluorometer for sensitive and rapid leishmania detection in sandflies. J Fluoresc 2014; 24: 267-277.
69 - Singh G, Vajpayee P, Rani N, Jyoti A, Gupta KC and Shanker R. Bio-capture of S. Typhimurium from surface water by aptamer for culture-free quantification. Ecotoxicol Environ Saf 2012; 78: 320-326.
70 - Laube T, Cortes P, Llagostera M, Alegret S and Pividori MI. Phagomagnetic immunoassay for the rapid detection of Salmonella. Appl Microbiol Biotechnol 2014; 98: 1795-1805.
71 - Vibbert HB, Ku S, Li X, Liu X, Ximenes E, Kreke T, Ladisch MR, Deering AJ and Gehring AG. Accelerating sample preparation through enzyme-assisted microfiltration of Salmonella in chicken extract. Biotechnol Prog 2015; 31: 1551-1562.