Fitzgerald A C, Edrington T S, Looper M L, Callaway T R, Genovese K J, Bischoff K M, McReynolds J L, Thomas J D, Anderson R C, Nisbet D J
Department of Animal and Range Sciences, New Mexico State University, Las Cruces, NM, USA.
Lett Appl Microbiol. 2003;37(5):392-8. doi: 10.1046/j.1472-765x.2003.01417.x.
To examine factors affecting faecal shedding of the foodborne pathogens Escherichia coli O157:H7 and Salmonella in dairy cattle and evaluate antimicrobial susceptibility of these isolates.
Faecal samples were obtained in replicate from lactating (LAC; n = 60) and non-lactating (NLAC; n = 60) Holstein cattle to determine influence of heat stress, parity, lactation status (LAC vs NLAC) and stage of lactation [</=60 or >60 days in milk (DIM)] and cultured for E. coli O157:H7 and Salmonella. A portion of the recovered isolates were examined for antimicrobial susceptibility using the broth microdilution technique.
No effects of heat stress were observed. Lactating cows shed more (P < 0.01) E. coli O157:H7 than NLAC cows (43% vs 32%, respectively). Multiparous LAC cows tended to shed more (P = 0.06) Salmonella than primiparous LAC cows (39% vs 27%, respectively). Parity did not influence (P > 0.10) bacterial shedding in NLAC cows. Cows </=60 DIM shed more (P < 0.05) Salmonella than cows >60 DIM. Seventeen Salmonella serotypes were identified with the most prevalent being Senftenberg (18%), Newport (17%) and Anatum (15%). Seventy-nine of the Salmonella isolates were resistant to at least one of the seven antibiotics. Escherichia coli O157:H7 isolates were resistant to 11 different antibiotics with multiple resistance to nine or more antibiotics observed in five isolates.
This study demonstrated differences in the shedding patterns of foodborne pathogens due to the stage of the milk production cycle and may help identify times when on-farm pathogen control would be the most effective.
研究影响奶牛食源性病原体大肠杆菌O157:H7和沙门氏菌粪便排出的因素，并评估这些分离株的抗菌药敏性。
从泌乳期（LAC；n = 60）和非泌乳期（NLAC；n = 60）的荷斯坦奶牛重复采集粪便样本，以确定热应激、胎次、泌乳状态（LAC与NLAC）和泌乳阶段[产奶天数（DIM）≤60天或＞60天]的影响，并对大肠杆菌O157:H7和沙门氏菌进行培养。使用肉汤微量稀释技术对部分回收的分离株进行抗菌药敏性检测。
未观察到热应激的影响。泌乳奶牛排出大肠杆菌O157:H7的比例高于非泌乳奶牛（分别为43%和32%，P < 0.01）。经产泌乳奶牛排出沙门氏菌的比例往往高于初产泌乳奶牛（分别为39%和27%，P = 0.06）。胎次对非泌乳奶牛的细菌排出没有影响（P > 0.10）。产奶天数≤60天的奶牛排出沙门氏菌的比例高于产奶天数＞60天的奶牛（P < 0.05）。鉴定出17种沙门氏菌血清型，最常见的是森夫滕贝格（18%）、纽波特（17%）和阿纳托姆（15%）。79株沙门氏菌分离株对七种抗生素中的至少一种耐药。大肠杆菌O157:H7分离株对11种不同抗生素耐药，五株分离株对九种或更多抗生素多重耐药。
本研究表明，由于产奶周期阶段不同，食源性病原体的排出模式存在差异，这可能有助于确定农场病原体控制最有效的时间。
