The objective of this study was to determine if immunosuppression through daily dexamethasone (DEX) infusion altered Salmonella translocation from the gastrointestinal tract. Weaned Holstein steers (n = 20; body weight [BW] = 102 ± 2.7 kg) received DEX (n = 10; 0.5 mg/kg BW) or saline (control [CON]; n = 10;) for 4 days (from day −1 to 2) before oral inoculation of naldixic acid-resistant Salmonella enterica Typhimurium (SAL; 3.4 × 10⁶ colony-forming units [CFU]/animal) on day 0. Fecal swabs were obtained daily, and blood was collected daily for hematology. At harvest (day 5), ileum, cecal fluid, lymph nodes (ileocecal, mandibular, popliteal, and subscapular), and synovial (stifle, coxofemoral, and shoulder) samples were collected for isolation of the inoculated strain of SAL. White blood cell (WBC) and neutrophil concentrations were elevated (p < 0.01) in DEX calves following each administration event. Following inoculation, 100% of DEX calves shed the experimental strain of SAL for all 5 days, 90% of CON calves shed from day 1 to 3, and 100% of CON calves shed from day 4 to 5. Greater (p < 0.01) concentrations of SAL were quantified from the cecum of DEX calves (3.86 ± 0.37 log CFU/g) compared with CON calves (1.37 ± 0.37 log CFU/g). There was no difference in SAL concentrations between DEX and CON calves in ileal tissue (p = 0.07) or ileocecal (p = 0.57), mandibular (p = 0.12), popliteal (p = 0.99), or subscapular (p = 0.83) lymph nodes. Of the stifle samples collected, 3.3% were positive for SAL, highlighting a contamination opportunity during hindquarter breakdown. While more research is needed to elucidate the interactions of immunosuppression and pathogen migration patterns, these data confirm that orally inoculated SAL can translocate from the gastrointestinal tract and be harbored in atypical locations representing a food safety risk.

中文翻译：

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荷斯坦犊牛轻度免疫抑制后口服接种沙门氏菌的易位和碎牛肉样品中沙门氏菌的存在。

本研究的目的是确定通过每日地塞米松 (DEX) 输注进行的免疫抑制是否会改变沙门氏菌从胃肠道的易位。断奶荷斯坦公牛（n  = 20；体重 [BW] = 102 ± 2.7 kg）接受 DEX（n  = 10；0.5 mg/kg BW）或生理盐水（对照 [CON]；n  = 10；）4 天（从第 -1 至 2 天），然后口服接种耐纳尔地克酸的鼠伤寒沙门氏菌（SAL；3.4 × 10 ⁶集落形成单位 [CFU]/动物）在第 0 天。每天获得粪便拭子，每天收集血液用于血液学。在收获时（第 5 天），收集回肠、盲肠液、淋巴结（回盲部、下颌骨、腘骨和肩胛下）和滑膜（膝关节、髋股骨和肩部）样品以分离接种的 SAL 菌株。 每次给药事件后，DEX 小牛的白细胞 (WBC) 和中性粒细胞浓度升高 ( p < 0.01)。接种后，DEX牛犊的100％棚SAL的实验菌株对所有5天，90％CON牛犊的从第1天棚〜3，CON牛犊的100％从第4天棚5大（p < 0.01) 与 CON 小牛 (1.37 ± 0.37 log CFU/g) 相比，从 DEX 小牛的盲肠中量化 SAL 浓度 (3.86 ± 0.37 log CFU/g)。DEX 和 CON 小腿在回肠组织 ( p  = 0.07) 或回盲部 ( p  = 0.57)、下颌 ( p  = 0.12)、腘 ( p  = 0.99) 或肩胛下 ( p )中的 SAL 浓度没有差异 = 0.83) 淋巴结。在收集的窒息样本中，3.3% 的 SAL 呈阳性，突出了后躯分解期间的污染机会。虽然需要更多的研究来阐明免疫抑制和病原体迁移模式的相互作用，但这些数据证实口服接种的 SAL 可以从胃肠道转移并藏匿在代表食品安全风险的非典型位置。