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We describe two outbreaks of multidrug-resistant (MDR) Salmonella I 4,[5],12:i:− infection, occurring in 2015 to 2016, linked to pork products, including whole roaster pigs sold raw from a...

Salmonella Infantis has been the etiological agent of numerous foodborne outbreaks of nontyphoidal Salmonella. Consequently, there is an emergent need to mitigate Salmonella Infantis among poultry. Thus, this study evaluated the efficacy of cetylpyridinium chloride (CPC) versus peroxyacetic acid (PAA), on bone-in, skin-on chicken thighs for the reduction of Salmonella and changes in the microbiota. Exactly 100 skin-on, bone-in chicken thighs (2 trials, 0 and 24 h, k = 5, n = 5, N = 50) were inoculated with 108 CFU/mL of a nalidixic acid resistant strain of S. Infantis for an attachment of 106 CFU/g. Thighs were treated with 20 s part dips (350 mL): a no inoculum, no treatment control (NINTC); no treatment control (NTC); tap water (TW); TW+CPC; TW+PAA. Following treatment, thighs were rinsed in 150 mL of nBPW, and rinsates were collected. Rinsates were spot plated for Salmonella and aerobic bacteria (APC). Log10 transformed counts were analyzed using a mixed-effects model (random effect = trial) with means separated using Tukey's HSD (P ≤ 0.05). The genomic DNA of rinsates was extracted, and the 16S rDNA was sequenced on an Illumina MiSeq. Microbiota data were analyzed using QIIME2, with data considered significant at P ≤ 0.05 (main effects) and Q≤0.05 (pairwise differences). Treatment × time interactions were observed for both Salmonella and APC (P < 0.05). The treatment of thighs with PAA and CPC reduced Salmonella and APC in respect to the controls. Numerically, thighs treated with CPC had less Salmonella (4.29 log10CFU/g) and less APC (4.56 log10CFU/g) at 24 h than all other treatments (P > 0.05). Differences in diversity metrics were not consistently observed between treatments; however, in trial 2, the NTC treated thighs were different than those treated with CPC (P < 0.05; Q < 0.05). In both trials, ANCOM, the analysis of microbiome compositional profiles, revealed shifts at both the phylum and order levels with thighs being different in the relative abundances of Proteobacteria (P < 0.05). In conclusion, treatment of skin-on poultry parts with CPC may reduce the risk of foodborne outbreaks caused by Salmonella Infantis.

SUMMARY Salmonellosis is a significant public health risk and is often associated with the consumption of poultry products. Colonization of poultry by Salmonella may be affected by dietary ingredients. The objective of the study was to evaluate the effects of hulless barley (HB) and β-glucanase (BGase) on Salmonella colonization in broiler chickens. Day-old broilers (200) were placed in battery cages and fed diets with and without high β-glucan HB (CDC Fibar; 0 and 60%) and BGase (Econase GT 200 P from ABVista; 0 and 0.1%) in a 2 × 2 factorial arrangement. Each treatment was assigned to 10 cages. All the birds were orally challenged with Salmonella Enteritidis LS101 strain at d 21. Broilers were infected with Salmonella Infantis before the S. Enteritidis challenge, and feeding HB decreased Salmonella positive cloacal swabs (%). HB decreased the percentage of birds positive for Salmonella in the spleen at pre-challenge and d 1 post-challenge, whereas increased the percentage positive for the spleen at d 4 post-challenge. BGase did not affect Salmonella colonization and translocation.

The objective of this study was to use microplate immunocapture (IC) to reduce the enrichment time required for detection of Salmonella in pet food with the 3 M Molecular Detection System (MDS) or selective plating on XLD. Dog food and pig ear treats were inoculated with Salmonella Infantis at concentrations of 100–104 CFU/25 g, followed by a 3-h enrichment, then microplate IC and 3 M MDS or microplate IC and selective plating on XLD. Another set of samples underwent a traditional 24-h enrichment followed by 3 M MDS or selective plating. Based on the results of three independent trials, microplate IC followed by selective plating enabled detection of Salmonella in 100% of dog food and treat samples tested, including at levels as low as 100 CFU/25 g. Microplate IC coupled with 3 M MDS enabled detection of Salmonella in dog food and treat samples down to levels of 100 CFU/25 g, with an overall detection rate of 92%. These results indicate high potential for microplate IC to be used in place of the traditional 24-h enrichment step, enabling detection of Salmonella in complex matrices when coupled with 3 M MDS or selective plating.

The vast majority of eggs in Australia are washed prior to packing to remove dirt and fecal material and to reduce the microbial contamination of the egg shell. The egg contents can be an ideal growth medium for microorganisms which can result in human illness if eggs are stored improperly and eaten raw or undercooked, and it is estimated that egg-related salmonellosis is costing Australia $44 million per year. Egg shell characteristics such as shell thickness, amount of cuticle present, and thickness of individual egg shell layers can affect the ease with which bacteria can penetrate the egg shell and washing could partially or completely remove the cuticle layer. The current study was conducted to investigate the effects of egg washing on cuticle cover and effects of egg shell quality and cuticle cover on Salmonella Infantis penetration of the egg shell. A higher incidence of unfavorable ultrastructural variables of the mammillary layer such as late fusion, type B bodies, type A bodies, poor cap quality, alignment, depression, erosion and cubics were recorded in Salmonella penetrated areas of egg shells. The influence of egg washing on the ability of Salmonella Infantis on the egg shell surface to enter the egg internal contents was also investigated using culture-based agar egg penetration and real-time qPCR based experiments. The results from the current study indicate that washing affected cuticle cover. There were no significant differences in Salmonella Infantis penetration of washed or unwashed eggs. Egg shell translucency may have effects on Salmonella Infantis penetration of the egg shell. The qPCR assay was more sensitive for detection of Salmonella Infantis from egg shell wash and internal contents than traditional microbiological methods. The agar egg and whole egg inoculation experiments indicated that Salmonella Infantis penetrated the egg shells. Egg washing not only can be highly effective at removing Salmonella Infantis from the egg shell surface, but also allows subsequent trans-shell and trans-membrane penetration into the egg. Consequently, it is important to prevent recontamination of the egg after washing.

Chilled breasts of chicken were inoculated with Salmonella infantis or Pseudomonas aeruginosa and then given one of the following treatments: (i) exposure to gaseous ozone (>2000 ppm for up to 30 min); (ii) storage under 70% CO2:30% N2; and (iii) exposure to gaseous ozone (>2000 ppm for 15 min) followed by storage under 70% CO2:30% N2; all storage at 7 °C. Gaseous ozone reduced the counts of salmonellae by 97% and pseudomonads by 95%, but indigenous coliforms were unaffected. Under the modified atmosphere, the cell count of S. infantis was reduced by 72% following initial exposure and then stabilised, coliforms grew, but Ps. aeruginosa behaved like S. infantis––initial reduction (58%) followed by stability. Exposure to gaseous ozone followed by gas packaging allowed survival of S. infantis, Ps. aeruginosa and coliforms over 9 days at 7 °C, but there was no evidence of any sensory deterioration. It is proposed that the latter treatment could, in a modified form perhaps, be used to reduce the contamination of chicken carcasses with salmonellae and improve their shelf-life.

Aerobic mesophilic counts (AMC), coliform (CC) and coliform resuscitation counts (CRCs) were obtained by swabbing 50 cm(2) areas at three sites (ham, belly and neck) on pig carcasses, after each of seven stages of the slaughter/dressing process (bleeding, scalding, dehairing, singeing, polishing, evisceration and chilling). In most cases, there were no statistical differences (P>0.05) among the counts derived by these three methods. Reductions in counts at individual sites were observed after scalding (3.5 log(10) cfu cm(-2)), and singeing (2.5 log(10) cfu cm(-2)). Increases in counts at individual sites were observed after dehairing (2.0 log(10) cfu cm(-2)) and polishing (1.5 log(10) cfu cm(-2)). The incidence of Salmonella on pig carcasses was also obtained by swabbing the outside surfaces of 100 half carcasses. Information on the incidence of Salmonella in scald tank water (108 samples) was also investigated. Carcass swabs and scald tank water were examined for the presence of Salmonella using standard enrichment methods. Salmonella were detected on 31% of carcasses immediately after bleeding, 7% of carcasses immediately after dehairing and evisceration, and 1% of carcasses immediately after scalding. Serovars included Salmonella Typhimurium, Salmonella Hadar, Salmonella Infantis and Salmonella Derby. No Salmonella were recovered from samples of scald tank water. The impact of pig slaughter/dressing processes on carcass microbiology and their potential use as critical control points (CCPs) during pork production are discussed.

The effect of a siderophoric compound, ferrioxamine E, in the pre-enrichment broth on determining of Salmonella infantis in environmental samples was tested with combination of various pre-enrichment times and enrichment temperatures of 37 and 43 degrees C. Ferrioxamine E slightly improved the determination efficiency of this bacterium but the pre-enrichment time could not be reduced below 17 hours. The enrichment temperature of 43 degrees C was better than of 37 degrees C. The mixing ratios of 1:100 or 1:1000 for samples and pre-enrichment broth were more successful than the ratio of 1:10 as recommended by ISO.

The efficacy of motility enrichment on modified semisolid Rappaport-Vassiliadis medium (MSRV) and an automated conductance method for the detection of Salmonella in environmental samples was evaluated. Two hundred and ten environmental samples from unrestricted areas of a milk powder factory, 49 of which were artificially contaminated with Salmonella infantis, were examined. From exactly 100 samples Salmonella could be isolated. With the conventional (ISO-DIS 6579) method a 100% score was obtained, whereas the MSRV method gave 82 positive results. The conductance method permitted the detection of Salmonella in only 66 samples. The use of Rambach agar improved isolation efficiency of Salmonella from enrichment broths.

The competitive exclusion (CE) concept has been tested against both non-invasive and invasive salmonella serotypes. Studies with different challenge models indicate that CE treatment is likely to protect the young bird against all serotypes that are capable of intestinal colonization. Spray or 'droplet' application of the CE-treatment material was compared with administration in the first drinking water. Both methods gave a similar degree of protection against Salmonella infantis. A study was made to compare protection of newly hatched chicks and turkey poults by the one commercial CE product Broilact, and two similar preparations involving intestinal microorganisms from an adult turkey. Each preparation protected both avian species when administered orally prior to challenge, but the degree of protection obtained varied with the type of preparation and its host origin.

SUMMARY Experimental oral infection of seven lambs with S. infantis , designed to determine the pathogenesis of infection and evaluate the efficacy of diagnostic procedures, is described. Clinical disease occurred in one lamb given 2 × 10 11 organisms and two of six lambs given 2 × 10 10 organisms. Observations were made on the clinical pathology, bacteriology and serology during the course of infection and extensive bacteriological examinations were undertaken at post-mortem examination on the lambs which were slaughtered serially during the course of infection.

Six-month-old cockerels and point-of-lay pullets were infected orally with S infantis (1 × 1010). The cockerels were slaughtered at intervals up to 42 days, and the pullets slaughtered 20 weeks, after infection. Infection produced no clinical disease and minimal changes were observed at autopsy. Serological responses were transient, frequently absent three to six weeks after infection, no response at all being recorded in some birds. Faecal excretion was observed most frequently during the early stages of infection. There was no evidence of egg transmission.

Summary The effect of zinc bacitracin on the growth of Salmonella infantis in the intestine of experimental orally infected 2-day-old broiler chicks was studied. At the age of 5 weeks the chicks which had received zinc bacitracin showed a lower incidence of salmonellae than those in the control group. Chicks pretreated with the intestinal flora of adult fowls (Callus domcsticus), whether receiving zinc bacitracin in the feed or not, were equally resistant against the colonization of S. infantis as compared with chicks which had no such pretreatment. The intestinal flora of adult fowls cultured in vitro, with or without zinc bacitracin, prevented the colonization of S. infantis, while flora from the same source cultured with tetracycline hydrochloride lacked this effect.

Effects of storage at 5 ad -18 C for up to 28 days and high and low inoculation levels on survival of Salmonella infantis and Staphylococcus aureus on smoked broiler halves were investigated. S. infantis and Staph. aureus counts were significantly reduced during storage. The reduction in counts of S. infantis could not be attributed solely to either temperature or inoculation levels. Storage at 5 C significantly (P less than .05) reduced Staph. aureus counts on smoked broiler halves as compared to storage at -18 C. For Staph. aureus, low inoculation levels (10(3) to 10(4) organisms/ml) resulted in significantly higher mortality rates than did high inoculation levels (10(7) to 10(8) organisms/ml). At both storage conditions and inoculation levels, Staph. aureus was able to maintain higher populations than S. infantis.

The effect of alkaline conditions (pH 10.5 for 30-60 min at 23°C) on the extraction of protein from mechanically deboned poultry residues (MDPR) was examined with respect to the general bacterial flora, coliforms and salmonellae. Standard plate counts decreased from 1.5 × 103 CFU/g in the MDPR to 2.0 × 102 CFU/g in the freshly extracted protein curd; coliform counts decreased from 4.9 × 101 MPN/g to 0. Coliforms survived only when the MDPR was mishandled for 5 h at 23°C before alkaline extraction whereas salmonellae appeared to be eliminated entirely, irrespective of preincubation abuse of the MDPR or introduction of increased levels of Salmonella infantis . Spoilage of the protein curds occurred in 14 days at 3°C but there was no increase in coliform numbers. Reappearance of salmonellae following storage was seen only in the protein extracted from MDPR inoculated with S. infantis . The destruction of salmonellae by pH 10 was confirmed in a tryptic soy broth model system, but only under ambient temperature exposure; neither growth nor destruction occurred at 3 or 10°C. It was concluded that alkaline extraction of protein from MDPR using the suggested operating conditions does not exaggerate any public health hazard involving salmonellae.

Growth and inhibition of Salmonella infantis , Enterobacter aerogenes and Escherichia coli in fermenting soybeans during tempeh production were studied in presence and absence of Lactobacillus plantarum . In fermenting unacidified soybeans S. infantis grew by 7 log units in 40 h. E. coli and E. aerogenes grew by 6 and 7 log units respectively. A similar pattern of growth of the three test organisms in fermenting acidified beans was also noted. Further inoculation of unacidified cooked beans with L. plantarum at a level of 106/g resulted in a complete inhibition of the test organisms in the product. On acidified cooked beans a lower level of L. plantarum inoculum (102/g) was enough to show a complete inhibitory effect. The lowering of the pH in fermenting beans by L. plantarum might have played a role in the destruction of the test organisms.

A total of 223 retail samples consisting of chicken pieces (81), Kebab and Kufta (36), Ground meat (33), Beefburger (29), Steak beef (25) and liver (19) were analyzed and revealed the presence of Salmonella sp. 16·14% of the samples. Of the nine different serotypes isolated, Salmonella infantis was predominant.

A sequence-specific endonuclease was isolated from a strain of Salmonella infantis. Its recognition sequence proved to be identical to that of restriction endonuclease · AvaII (an endonuclease from the blue-green alga Anabaena variabilis), G↓G(AT)CC.