Seattle-King County Public Health Friday announced it is investigating a salmonellosis outbreak caused by Salmonella Stanley, an uncommon strain of Salmonella bacteria.

Six persons infected with Salmonella Stanley were reported to Public Health during July 17–July 24.

On July 26-27, genetic fingerprinting results for four of the six cases became available, and all had the same genetic fingerprint, suggesting that they have some common source of infection; genetic fingerprinting for the other two cases is pending.

This fingerprint has only been seen twice before in King County where two to six cases of Salmonella Stanley have been reported annually over the past several years. Public Health is attempting to interview each case to gather information about possible risk factors for infection.

The source of the outbreak is still under investigation.

The median age of the cases is 21 years; three cases are female and three are male. None of the cases are known to have been hospitalized. Additional details on the investigation will be posted as they are available.

Salmonellosis is a bacterial infection that is often spread through the fecal-oral route, through contaminated food and water, or through contact with animals and their environments. Symptoms of salmonellosis include nausea, vomiting, diarrhea, headache, fever, chills, and abdominal cramping. Illness typically lasts several days and people can spread infection to others even after symptoms resolve.

To prevent Salmonella infection:

  • Wash hands with soap and water after going to the bathroom, changing diapers, touching animals, and before eating or preparing food.
  • Cook all meats thoroughly, especially poultry.
  • Wash cutting boards and counters used for meat or poultry preparation immediately after use to avoid cross contaminating other foods.

Here is an interesting research article on the likely source of the outbreak.

Characterization of Isolates of Salmonella enterica Serovar Stanley, a Serovar Endemic to Asia and Associated with Travel

Rene S. Hendriksen,a Simon Le Hello,b Valeria Bortolaia,a Chaiwat Pulsrikarn,d Eva Møller Nielsen,c Srirat Pornruangmong,d Phattharaporn Chaichana,d Christina Aaby Svendsen,a François-Xavier Weill,b and Frank M. Aarestrupa J Clin Microbiol. 2012 Mar; 50(3): 709–720. doi:  10.1128/JCM.05943-11 This article has been cited by other articles in PMC. Go to: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3295172/

Abstract

Salmonella enterica serovar Stanley (S. Stanley) is a common serovar in Southeast Asia and was the second most common serovar implicated in human salmonellosis in Thailand in the years 2002 to 2007. In contrast, this serovar is relatively uncommon in Europe. The objective of this study was to characterize a collection of S. Stanley strains isolated from Thai (n = 62), Danish (n = 39), and French (n = 24) patients to gain a broader understanding of the genetic diversity, population dynamics, and susceptibility to antimicrobials. All isolates were characterized by pulsed-field gel electrophoresis and antimicrobial susceptibility testing. The molecular mechanisms of resistance to extended-spectrum cephalosporins and plasmid-mediated resistance to quinolones were characterized by PCR and sequencing. Plasmid profiling, replicon typing, and microarray analysis were used to characterize the genetic mechanisms of antimicrobial resistance in 10 extended-spectrum cephalosporinase-producing isolates. Considerable
genetic diversity was observed among the isolates characterized with 91 unique XbaI pulsed-field gel electrophoresis (PFGE) patterns, including 17 distinct clusters consisting of two to seven indistinguishable isolates. We found some of the S. Stanley isolates isolated from patients in Europe were acquired during travel to Southeast Asia, including Thailand. The presence of multiple plasmid lineages carrying the extended-spectrum cephalosporinase-encoding blaCMY-2 gene in S. Stanley isolates from the central part of Thailand was confirmed. Our results emphasize that Thai authorities, as well as authorities in other countries lacking prudent use of antimicrobials, should improve the ongoing efforts to regulate antimicrobial use in agriculture and in clinical settings to limit the spread of multidrug-resistant Salmonella isolates and plasmids among humans and pigs in Thailand and abroad.