Detection of Salmonella spp. by Conventional Bacteriology and by Quantitative Polymerase-Chain Reaction in Commercial Egg Structures

Abstract

Conventional bacteriology techniques and quantitative polymerasechain reaction (qPCR) were applied to the eggshell, albumen, and yolk of washed and unwashed commercial white and brown eggs, to detect Salmonella spp. Pooled samples of eggshells, albumen, and yolk of white and brown eggs were collected at the poultry house and at the egg-storage room. Salmonella spp. was detected by conventional bacteriology in 5.4% (21/387) of analyzed samples and in 16% (68/387) by qPCR. In the 114 unwashed white eggs samples of eggshell, albumen and yolk, the bacterium was identified in 2.6% of the eggs (3/114) by conventional bacteriology and in 13.2% (15/114) by qPCR. In the 90 samples of washed eggs, 6.7% (6/90) were contaminated as detected by conventional bacteriology and 10.0% (9/90) by qPCR. In the 81 samples of unwashed brown eggs, Salmonella spp. was detected in 6.1% of the eggs (5/81) by conventional bacteriology and 27.2% (22/81) by qPCR. In the 102 samples of brown washed eggs, 6.9% (7/102) where positive by conventional bacteriology and 35.3% (16/102) by qPCR. All samples detected as positive by conventional bacteriology were also positive by qPCR. Salmonella Agona represented 18.2% (4/22) of identified serovars, Salmonella enterica subs. enterica O: 4.5 18.2%

Risk factors associated with Salmonella prevalence, its antibiotic resistance, and egg antibiotic residues in the layer farming environment

“…S. enterica Corvallis is most commonly found in poultry carcasses following the slaughtering process in several countries, including Thailand [13], Brazil [14], Malaysia [15], and China [16]. In this study, the prevalence of Corvallis in laying farm environmental samples was high when compared with the results of Moraes et al [17] and Camba et al [18]. This may have been due to the presence of rodents at the farm (OR=25, p=0.01), as rodents can be the main reservoir of this serovar, as shown in the study by Camba et al [18].…”

Detection and quantification of Salmonella spp. in poultry slaughterhouses of southern Brazil

“…Previous studies have already shown that qPCR is more effective than conventional bacteriological methods for the detection of Salmonella spp. [18]. However, it is important to highlight that non-viable cells can be detected by qPCR, which does not occur in traditional methods of culture and isolation that require viable cells for quantification [19].…”

Antimicrobial Resistance in Salmonella Serovars Isolated From an Egg-Producing Region in Brazil

“…Previous reports detected Salmonella spp. in 3.98% cloacal (Andrade et al, 1995), 6.25% fecal samples (Salles et al, 2008), and 25% mature flocks (Freitas Neto et al, 2014) in Brazilian layer farms, suggesting that biosecurity failures may allow the dissemination of this pathogen among farms (Iwabuchi et al, 2010;Moraes et al, 2016). Twenty-two serovars and two rough strains were identified in 80 isolates ( Table 2).…”

“…The low prevalence of some serovars determined in the present study may be attributed to their preference for other animal or plant infection targets. For instance, S. Enteritidis and S. Schwarzengrund serovars were the most prevalent in eggs samples (Moraes et al, 2016), and S. Agona was associated with the consumption of contaminated fishmeal by layers (Berchieri Junior et al, 1985;Clark et al, 1973).…”

“…Bacteria of the genus Salmonella are widely distributed in nature and may infect both humans and animals, and more than 2659 Salmonella serovars have been identified (Issenhuth-Jeanjean et al, 2014). Several of these serovars cause paratyphoid infection (Salles et al, 2008;Kottwitz et al 2008;Freitas Neto et al, 2014;Perdoncini et al, 2014;Moraes et al, 2016). In addition, non-typhoidal Salmonella serovars may persist in the digestive tract of infected chickens without causing disease and are considered the main source of foodborne infections in humans, mainly due to the consumption of poultry products (Shah et al, 2017).…”