Bosilevac Joseph M, Guerini Michael N, Kalchayanand Norasak, Koohmaraie Mohammad
U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933-0166, USA.
Appl Environ Microbiol. 2009 Apr;75(7):1892-900. doi: 10.1128/AEM.02530-08. Epub 2009 Feb 6.
Commercially produced ground beef samples (n = 4,136) were collected from seven regions of the United States over a 24-month period (July 2005 to June 2007) and analyzed for the presence of Salmonella enterica by using methods that concurrently provided total prevalence and enumerable levels. The overall prevalence of Salmonella strains was 4.2%. Enumeration showed that 94.2% were present at levels below 2 CFU/g. Regional monthly prevalences of Salmonella strains varied from 1.8% to 6.5% but were not statistically different (P > 0.05). All Salmonella isolates were serotyped and their antibiotic susceptibilities determined and analyzed by pulsed-field gel electrophoresis (PFGE). The most common serotypes identified were Salmonella enterica serotypes Montevideo, Anatum, Muenster, and Mbandaka, with these accounting for one-half of the isolates obtained. The prevalence of multidrug-resistant (MDR) Salmonella was determined to be 0.6%. The most common MDR serotypes were Salmonella enterica serotypes Dublin, Reading, and Typhimurium. MDR strains had resistance to between 2 and 10 antibiotics. There were no regional differences in prevalence of MDR Salmonella. PFGE analysis revealed that indistinguishable XbaI and AvrII restriction digest patterns (RDPs) could be observed in isolates of the same serotype found in different regions and months of sampling. The RDPs of 19 Salmonella strains were compared to RDPs in the PulseNet USA database. Thirteen were indistinguishable from existing patterns, and the number of records for each ranged from 1 to 478. These data show that Salmonella prevalence in commercial ground beef is low and suggest that attempts to identify sources contributing to Salmonella in ground beef by serotype, antibiogram, and PFGE cannot be made without additional documented evidence.
在24个月期间（2005年7月至2007年6月），从美国七个地区采集了4136份市售碎牛肉样本，采用能同时提供总流行率和可计数水平的方法分析其中肠炎沙门氏菌的存在情况。沙门氏菌菌株的总体流行率为4.2%。计数显示，94.2%的菌株含量低于2 CFU/g。沙门氏菌菌株的区域月度流行率在1.8%至6.5%之间，但无统计学差异（P>0.05）。对所有沙门氏菌分离株进行血清分型，并通过脉冲场凝胶电泳（PFGE）测定和分析其抗生素敏感性。鉴定出的最常见血清型为肠炎沙门氏菌蒙得维的亚、阿纳托姆、明斯特和班达卡血清型，这些血清型占分离株的一半。多重耐药（MDR）沙门氏菌的流行率为0.6%。最常见的MDR血清型为肠炎沙门氏菌都柏林、雷丁和鼠伤寒血清型。MDR菌株对2至10种抗生素耐药。MDR沙门氏菌的流行率无区域差异。PFGE分析显示，在不同地区和采样月份发现的同一血清型分离株中可观察到难以区分的XbaI和AvrII限制性消化模式（RDPs）。将19株沙门氏菌菌株的RDPs与美国脉冲网数据库中的RDPs进行比较。其中13株与现有模式难以区分，每种模式的记录数从1到478不等。这些数据表明，市售碎牛肉中沙门氏菌的流行率较低，并表明在没有额外书面证据的情况下，无法通过血清型、抗菌谱和PFGE来确定碎牛肉中沙门氏菌的来源。
