Greene Sharon K, Stuart Andrew M, Medalla Felicita M, Whichard Jean M, Hoekstra Robert M, Chiller Tom M
Epidemic Intelligence Service, Office of Workforce and Career Development, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Foodborne Pathog Dis. 2008 Oct;5(5):669-80. doi: 10.1089/fpd.2008.0111.
Multidrug-resistant (MDR) Salmonella strains are associated with excess bloodstream infections, hospitalizations, and deaths compared with pansusceptible strains. Bovine products are sometimes a source of MDR Salmonella. To generate hypotheses for regional differences in risk factors for human infection, we analyzed distributions of the two most prevalent MDR Salmonella phenotypes in the United States, 2003-2005: (i) MDR-ACSSuT (resistant to at least ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline) Typhimurium; (ii) MDR-AmpC (resistant to at least ampicillin, chloramphenicol, streptomycin, sulfonamides, tetracycline, amoxicillin/clavulanic acid, and ceftiofur, and with decreased susceptibility to ceftriaxone) Newport.
Participating public health laboratories in all states forwarded every 20th Salmonella isolate from humans to the National Antimicrobial Resistance Monitoring System for Enteric Bacteria for antimicrobial susceptibility testing. Among the serotypes Typhimurium and Newport isolates submitted 2003-2005, pansusceptible, MDR-ACSSuT Typhimurium, and MDR-AmpC Newport were identified. Patterns of resistance, demographic factors, and cattle density were compared across regions.
Of 1195 serotype Typhimurium isolates, 289 (24%) were MDR-ACSSuT. There were no significant differences in region, age, or sex distribution for pansusceptible versus MDR-ACSSuT Typhimurium. Of 612 serotype Newport isolates, 97 (16%) were MDR-AmpC, but the percentage of MDR-AmpC isolates varied significantly across regions: South 3%, Midwest 28%, West 32%, and Northeast 38% (p < 0.0001). The South had the lowest percentage of MDR-AmpC Newport isolates and also the lowest density of milk cows. More Newport isolates were MDR-AmpC in the 10 states with the highest milk cow density compared with the remaining states. Overall, 22% of pansusceptible Newport isolates but only 7% of MDR-AmpC Newport isolates were from patients <2 years of age. For both serotypes, MDR phenotypes had less seasonal variation than pansusceptible phenotypes.
This is the first analysis of the distribution of clinically important MDR Salmonella isolates in the United States. MDR-ACSSuT Typhimurium was evenly distributed across regions. However, MDR-AmpC Newport was less common in the South and in children <2 years of age. Information on individuals' exposures is needed to fully explain the observed patterns.
与全敏感菌株相比，多重耐药（MDR）沙门氏菌菌株与更多的血流感染、住院和死亡相关。牛肉制品有时是MDR沙门氏菌的一个来源。为了提出关于人类感染危险因素区域差异的假设，我们分析了2003 - 2005年美国两种最常见的MDR沙门氏菌表型的分布情况：（i）MDR - ACSSuT（对至少氨苄西林、氯霉素、链霉素、磺胺类药物和四环素耐药）鼠伤寒沙门氏菌；（ii）MDR - AmpC（对至少氨苄西林、氯霉素、链霉素、磺胺类药物、四环素、阿莫西林/克拉维酸和头孢噻呋耐药，且对头孢曲松敏感性降低）纽波特沙门氏菌。
所有州参与的公共卫生实验室每20株从人类分离出的沙门氏菌菌株就将其送至肠道细菌国家抗菌药物耐药监测系统进行药敏试验。在2003 - 2005年提交的鼠伤寒沙门氏菌和纽波特沙门氏菌血清型分离株中，鉴定出全敏感、MDR - ACSSuT鼠伤寒沙门氏菌和MDR - AmpC纽波特沙门氏菌。比较了各地区的耐药模式、人口统计学因素和牛的密度。
在1195株鼠伤寒沙门氏菌血清型分离株中，289株（24%）为MDR - ACSSuT。全敏感与MDR - ACSSuT鼠伤寒沙门氏菌在地区、年龄或性别分布上无显著差异。在612株纽波特沙门氏菌血清型分离株中，97株（16%）为MDR - AmpC，但MDR - AmpC分离株的百分比在各地区差异显著：南部为3%，中西部为28%，西部为32%，东北部为38%（p < 0.0001）。南部MDR - AmpC纽波特沙门氏菌分离株的百分比最低，奶牛密度也最低。与其他州相比，奶牛密度最高的10个州中，纽波特沙门氏菌分离株更多为MDR - AmpC。总体而言，22%的全敏感纽波特沙门氏菌分离株但仅7%的MDR - AmpC纽波特沙门氏菌分离株来自2岁以下患者。对于这两种血清型，MDR表型的季节变化均小于全敏感表型。
这是对美国临床上重要的MDR沙门氏菌分离株分布的首次分析。MDR - ACSSuT鼠伤寒沙门氏菌在各地区分布均匀。然而，MDR - AmpC纽波特沙门氏菌在南部和2岁以下儿童中较少见。需要有关个体暴露情况的信息来充分解释所观察到的模式。
