Ed Metzger from South West Ontario Veterinary Service, Monophasic Salmonella: Is It Really Associated With Clinical Disease?


Salmonella enterica serotype I 4,[5],12:i:-or “monophasic  Salmonella” was  rarely detected  prior  to  the  mid 1990’s.  This serotype  has  been  increasingly  isolated from swine in North America and Europe and has been  associated  with  a  number  of  human  disease outbreaks  that  were  associated  with  contaminated pork  products.  Although  increased  isolation  of Salmonella  I  4,[5],12:i:-from  swine  samples  has been  documented,  the  pathogenic  potential  of  this serovar  in  pigs  had not  been  reported.  Little  work has been done to confirm that this organism is truly a cause of digestive system disease in swine. These researchers at Iowa State wanted to better describe the  disease  causing  ability  of  Salmonella  enterica serotype I 4,[5],12:i:-.

The researchers were able to demonstrate a strong positive    association    between    histologic (microscopic)  lesions  consistent  with  enteric salmonellosis  and  isolation  of  Salmonella  I  4,[5],12:i:-. In most cases from which Salmonella I 4,[5],12:i:-or Salmonella Typhimurium were isolated, the  severity  of  histologic  lesions  was  similar. However,  the  percentage  of  cases  in  which histologic   lesions   consistent   with   enteric salmonellosis were present was lower for cases from which Salmonella I 4,[5],12:i:-(72%) was isolated than for cases from which Salmonella Typhimurium (94%) was isolated.

Take Home Message

  • Salmonella  I  4,[5],12:i:-,  based  on  this research,  is  a  likely  cause  of  enteric salmonellosis  that  is  very  similar  in  disease causing  ability  in  swine  to  Salmonella Typhimurium.
  • Salmonella  I  4,[5],12:i:- has  become  the predominant   disease   causing   Salmonella species in swine on a global basis
  • Expect  to  see  further  research  into  the characteristics  of  this  organisms  that  have allowed it to become predominant over other more established Salmonella.

Submitted by Ed Metzger, DVM

Ref: Arruda BL, Burrough ER, Schwartz KJ.Salmonella enterica I 4,[5],12:i:-Associated  with  Lesions  Typical  of  Swine  Enteric Salmonellosis.Emerg  Infect  Dis.  2019  Jul;25(7):1377-1379.  doi: 10.3201/eid2507.181453.



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