Comparison of Salmonella enterica serovar Bovismorbificans 2011 hummus outbreak strains with non-outbreak strains

abstract Eleven Salmonella enterica serovar Bovismorbificans isolates obtained from the U.S. District of Columbiaduring a 2011 hummus-associated foodborne outbreak were compared to 12 non-outbreak isolates. Allisolates from the outbreak demonstrated a single PFGE pattern that was distinctly different from otherisolates of S. Bovismorbificans as recorded in the PulseNet Database. Results from molecular analyses ofthe hummus-associated S. Bovismorbificans isolates indicate that the isolates from the outbreak wereunique and have acquired an 80e90 kb plasmid. The impact of this study is that the information gainedwill add and expand our knowledge of diversity of the S. Bovismorbificans serovar.Published by Elsevier Ltd. 1. IntroductionOutbreaks associated with a variety of Salmonella entericaserovars and food matrices continue to increase each year, makingidentification, differentiation and characterization of the variousserotypes in foodborne outbreak a high priority for the field of foodsafety. Every year approximately 40,000 cases of salmonellosis arereported in the United States. There are over 2500 different sero-vars of S. enterica, and some of the most recent reported cases of S.enterica associated with foodborne outbreaks include: S. Typhi-murium in ground beef, S. Heidelberg in Kosher broiled chickenlivers and ground turkey, S. Enteritidis in Turkish pine nuts, eggs,alfalfa sprouts and spicy sprouts, S. Agona in fresh imported pa-payas, S. Hadar in turkey burgers, S. Panama in Cantaloupe, S.Bareillyin spicy tuna,S. Braenderup in mangoes, and S. BredeneyinPeanut Butter (CDC Outbreaks).Human infections with S. enterica serovar Bovismorbificans arerelativelyinfrequentintheUnitedStates.Priorto2011,thelastmajoroutbreak associated with S. Bovismorbificans occurred in 2004 with35 confirmed cases associated with the consumption of alfalfasprouts (CDC Outbreaks). From 1999 to 2009, only 758 illnessesassociatedwithS.Bovismorbificanswerereported,comparedto1000confirmed cases associated with S. Enteritidis in 1999 alone (Food-borne Outbreak Online Database, CDC, www.cdc.gov/salmonella/outbreaks.html). The majority of foodborne outbreaks associatedwithS.BovismorbificanshasoccurredinEuropeandhavebeentracedtoporkproducts,lettuceandsprouts(Rimhanen-Finneetal.,2011).InFinland in 1994, 201 cases were reported from a large sprout-associated S. Bovismorbificans outbreak (Puohiniemi et al.,1997). InSweden in 1994, there was a large sprout-associated, S. Bovismorbi-ficansoutbreak(Ponkaetal.,1995)andasecondnationwideoutbreakoccurred in 2009 with 42 clinical isolates identified and was alsoassociated with ready-to-eat alfalfa sprouts. The sprouts sampleswere traced back to a domestic producer, but the seeds originated inItaly (Rimhanen-Finne et al., 2011). Over a 13 week period betweenNovember 2004 and March 2005, 525 cases of laboratoryconfirmedS. Bovismorbificans associated with raw pork were reported to TheRobert Koch Institute ( Rimhanen-Finne et al., 2011).From August through November of 2011, sesame seed paste(tahini) and humus containing a rare serotype of Salmonella causedillness in 23 people in 7 states, including the District of Columbia