A newly emergent, multi-drug-resistant Salmonella serotype has become increasingly prevalent in pigs, pig meat and foodborne human infections across Europe, say epidemiologists, who are urging quick action to prevent a new pandemic.

S. enterica serotype 4,[5],12:i:-, first isolated in the late 1980s from a chicken carcass in Portugal, was seen again in Spain in the late 1990s, and became the fourth most common Salmonella serotype in that country between 1998 and 2000. In an article published June 3 in the journal Eurosurveillance, Katie L. Hopkins, Ph.D., an epidemiologist at the Health Protection Agency in London, along with colleagues in France, Germany, Spain, Poland and the Netherlands, reported a marked increase in the prevalence of serotype 4,[5],12:i:- in human infections across Europe.

Human salmonellosis infections with serotype 4,[5],12:i:- have risen sharply in the United Kingdom, which recorded 151 in 2009 compared with 47 in 2005, a 321% increase in a period when overall incidence of salmonellosis decreased. In France, isolations of serovar 4,[5],12:i:- increased even more sharply, from 99 in 2005 to 410 in 2008; in Italy, from 59 infections in 2003 to 641 in 2009.

Most Salmonella disease is mild and self-limiting with gastrointestinal symptoms. However, immunocompromised patients, elderly patients, and people with rare cases of invasive disease, Salmonella bacteremia and meningitis, require treatment with antimicrobial drugs. Serotype 4,[5],12:i:- is resistant to ampicillin, streptomycin, sulphonamides and tetracyclines. “Antimicrobial resistance is a serious public health problem limiting the therapeutic options available to clinicians treating complicated Salmonella infections,” Dr. Hopkins and colleagues wrote (Euro Surveill. 2010;15(22):pii=19580).

The authors expressed concern that 4,[5],12:i:- could become the next Salmonella Typhimurium DT104, a drug-resistant serotype first isolated in humans in 1989 that caused outbreaks and fatal disease in Europe beginning in the 1990s, later to emerge in the United States and Canada. In recent years, multiresistant Typhimurium DT104 has waned in Europe, Dr. Hopkins and colleagues noted, but any benefit from its decline has been offset by the newcomer’s gains.

“Serovar 4,[5],12:i:- has already caused substantial outbreaks in several countries, with reports of severe infections and also deaths [6,7,9,10],” Dr. Hopkins and colleagues wrote. “In order to prevent a global epidemic of these newly emerging clones or strains, as occurred with Typhimurium DT104, appropriate intervention strategies need to be put in place as soon as possible, particularly in pig husbandry throughout the EU.”

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流行病学家说，存在于猪、猪肉和人类食源性感染中的一种新型多重耐药性沙门菌血清型在欧洲正变得日益流行，他们正强烈要求迅速采取行动，以防止发生新的大流行。

 

在20世纪80年代后期，科研人员在葡萄牙生产的鸡肉中首度分离出沙门菌血清型4,[5],12:i:- ，在20世纪90年代后期，在西班牙又再次发现了该血清型，且在1998~2000年间，该菌成为了该国第四大常见的沙门菌血清型。在6月3日发表于《欧洲监测》(Eurosurveillance)上的一篇论文中，英国保健局(伦敦)的流行病学家Katie L. Hopkins博士及其在法国、德国、西班牙、波兰和荷兰的同事报告说，在欧洲发生的人类食源性感染中血清型4,[5],12:i:-沙门杆菌的检出率显著增加。

 

在英国，由血清型4,[5],12:i:-沙门菌引发的人类感染例数已经急剧增加，与2005年发现的47例相比，2009年记录在案的病例数为151例，在沙门菌病总体发病率下降这段时间内，该血清型的检出率增加了321%。在法国，分离出血清型4,[5],12:i:-沙门菌的病例数的增长幅度甚至更大，其从2005年的99例增加至2008年的410例，在意大利，该血清型的感染者例数则由2003年的59例增加至2009年641例。

 

由沙门菌引发的大部分疾病都是伴有胃肠道症状的轻度自限性疾病。然而，免疫功能低下的患者、老年患者和伴有罕见侵袭性疾病的患者(如沙门菌血症和脑膜炎)则需要接受抗菌药物治疗。血清型4,[5],12:i:-沙门菌对氨苄青霉素、链霉素、磺胺类药物和四环素类抗生素均具耐药性。“该血清型对抗菌药物的耐药性构成了严重的公共卫生问题，且其还对临床医生治疗复杂性沙门菌感染的可用治疗选择造成了限制，” Hopkins博士及其同事写道(Euro Surveill. 2010;15(22):pii=19580)。

 

作者们就血清型4,[5],12:i:-沙门菌可能成为下一个鼠伤寒沙门菌DT104表达了自己的关注，这种耐药性血清型于1989年首度在人体中发现，并自20世纪90年代始便在欧洲引起了疾病暴发和致死性疾病，之后又在美国和加拿大出现。近年来，鼠伤寒沙门菌DT104在欧洲的流行性已经逐渐趋弱，Hopkins博士及其同事写道，但由这种出现新耐药菌所造成的损失已经抵消了DT104流行性减弱带来的全部收益。