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Wiki Markup*{+}Background:+* _Salmonella enterica_ subsp. _enterica_ serovar Heidelberg (antigenic formula 1,4,\[5\],12:r:1,2) is a serovar of the O:4 (B) serogroup. _S_. Heidelberg is commonly found in poultry meat in North America. In the U.S. and Canada, it has caused numerous infections in chickens. In the U.S., this serovar has caused a number of outbreaks that included the recent outbreak (October, 2013), linked to [raw chicken|http://www.cdc.gov/salmonella/heidelberg-10-13/index.html]; this outbreak was caused by a multidrug resistant _S._ Heidelberg strain (resistant to ampicillin, chloramphenicol, gentamicin, kanamycin, streptomycin, sulfisoxazole, and tetracycline). _S._ Heidelberg accounts for the 8.6% of ceftriaxone-resistant _Salmonella_ isolated from humans in the U.S. Recently, a [phage typing scheme|http://jcm.asm.org/content/41/9/4279.full] was developed for serovar Heidelberg in Canada; this scheme recognizes 49 phage types.   

Animal reservoir: S. Heidelberg is mostly found in chickens and turkeys. 

...

Year

Location

Associated source

Number of cases

2016US-multistateContact with Dairy Calves21

2013

US-multistate

Raw chicken

278

2011

US-multistate

Kosher Broiled Chicken Livers

190

2011

US-multistate

Ground turkey

136

2011

Europe

In-flight catering from Tanzania to Europe

22

2005

US-WI

Pig roast

25

2004

Canada

Food handler

45

2001

Australia

Eggs

12

Relevant genetic characteristics: Whole genome sequences for 15 strains of S. Heidelberg have been deposited at GenBank as of October, 2013. Genomic characteristics of the sequenced S. Heidelberg include (i) a genome size ranging from 4.73 to 4.98 Mb, (ii) a mol G+C% of 52.1, and (iii) 5,578 to 5,039 predicted genes. Many of these sequenced strains were have been implicated in recent outbreaks (2011 and 2012), in the U.S. Salmonella Heidelberg str. SARA33 is a multidrug resistant strain. This strain was found, in silico, to contain a novel integron cassette; in addition, it was found to carry the following resistance genes: aac(6′)-ly, aadA5, aadB, aa(6′)-33, and aadA1, sul1 and sul2, blaOXA-2 and blaTEM, tetD. Resistance genes in S. Heidelberg have been identified in the chromosome (resistant islands) and in plasmids. The plasmids that carried resistance genes represent different Different incompatibility types (IncAA/C, IncFIBFIB, IncHI2).HI2) have been identified in the plasmids that carried resistance genes in S. Heidelberg.

Phylogenetic and pan-genomic analyses that included two of the sequenced S. Heidelberg strains and other Salmonella serovars concluded that S. Heidelberg (i) belongs to clade A, according to den Bakker et al. (2011) classification, (ii) appears to have a single evolutionary origin, and (iii) contains 74 gene families unique to this serovar.  

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  1. http://www.cdc.gov/salmonella/heidelberg-02-13/
  2. http://www.cdc.gov/salmonella/heidelberg-10-13/index.html
  3. http://jcm.asm.org/content/41/9/4279.full
  4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3569330/
  5. https://www.cdc.gov/salmonella/heidelberg-11-16/index.html