CRISPRs: Molecular Markers for Tracking Antibiotic Resistant Strains of Salmonella Enterica
PENNSYLVANIA STATE UNIV STATE COLLEGE
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Within the CDCs 2013 report on antibiotic resistance threats in the US, antibiotic - resistant, Salmonella is classified as a serious threat, meaning these bacteria present a serious concern and require prompt and sustained action to ensure the problem does not grow. 1 In a landscape of historically evolving nomenclature, the speciation of Salmonella is complex and can be daunting. As members of the family Enterobacteriaceae, there are currently just two recognized species S. bongori and S. enterica with the latter having 6 main subspecies enterica , salamae , arizonae, diarizonae , houtenae , and indica , but over 2,500 serovars, serological variants based on their reactions to specific antibodies. Of the two types of Salmonella serovars typhoidal and nontyphoidal the typhoidal serovars S. Typhi and S. Paratyphi A, B and C are confined to human hosts and cause typhoid and paratyphoid enteric fevers. These are spread from human to human often shed by asymptomatic carriers who serve as important reservoirs via direct contact, improperly handled food or via drinking water contaminated with sewage. Globally, an estimated 27.1 million people are infected with enteric fever, and mortality is high 12 - 30 with 217,000 deaths annually. In the developed world, most cases are brought back by travelers from endemic areas, which include the Indian subcontinent, the Caribbean, Africa, South and Central America, and South Asia, where antibiotic resistance levels are high. Where needed, treatment is often empirical before the receipt of test results. Consequently, travel history is important and knowledge of local strains and resistance patterns is critical to effective therapy.
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