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Biological Health Hazard – Salmonella Outbreak (S. Stanley): Seattle – King County, Washington


Salmonella Stanley

Background: Salmonella Stanley (antigenic formula: 1,4,[5],12,[27]:d:1,2) is a serovar of the O:4 (B) serogroup. S. Stanley is a predominant serovar in South East Asia, which appears to have spread to Europe. Initial cases in Denmark were associated with patients that traveled to Thailand; however, multiple outbreaks in Europe associated with different sources (poultry, cheese, alfalfa sprouts) suggest that S. Stanley has been dispersed in Europe. In Asia, cases have been found in children under the age of 5. Multidrug resistant strains that encode extended spectrum beta-lactamases (enzymes that confer resistance to third generation cephalosporin) have been reported in clinical cases in Asia and Europe.

Animal reservoir: Pork was found to be the source of S. Stanley in Thailand, but outbreaks associated with turkey indicate that turkey is also a reservoir.

Geographical distribution: S. Stanley is prevalent in Asia, this serovar has been reported in Thailand, Taiwan, Japan, and Malaysia. In Europe, cases reported in Denmark were attributed to traveling to Asia.

Outbreaks: Multiple outbreaks have been linked to S. Stanley in Europe. In the US a recent outbreak linked with S. Stanley caused 14 cases and a recall of raw cashew cheese. In the EU an outbreak that last for 17 months appears to continue since cases with the same strain (identical PFGE) have been reported in 2014.

Food Safety Wiki – Salmonella Stanley (edited)

Seattle-King County Investigates six Salmonella Stanley cases

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.

29 July 2017
Source: Food Safety News [edited]

See Also

Salmonellosis, st Heidelberg – USA: MDR, cattle contact 20170803.5225307 – 2 August 2017
Salmonellosis – USA (08): FDA, contaminated raw retail meat & poultry, resistance 20160501.4195399 – 28 April 2016
Salmonellosis, st I 4,[5, 12:i:- – USA: (WA) pork, 2015 20160415.4160048 – 14 April 2016
Outbreak of Multidrug-Resistant Salmonella I 4,[5],12:i:- Infections Linked to Pork – December 2, 2015
Multi-drug Resistance Identified in WA Salmonella Outbreak – August 15, 2015


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


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.

Rene S. Hendriksena,

Simon Le Hellob,

Valeria Bortolaiaa,

Chaiwat Pulsrikarnd,

Eva Møller Nielsenc,

Srirat Pornruangmongd,

Phattharaporn Chaichanad,

Christina Aaby Svendsena,

François-Xavier Weillb and

Frank M. Aarestrupa

aNational Food Institute, Technical University of Denmark, WHO Collaborating Center for Antimicrobial Resistance in Foodborne Pathogens and European Union Reference Laboratory for Antimicrobial Resistance, Kgs. Lyngby, Denmark
bInstitut Pasteur, Unité des Bactéries Pathogènes Entériques, Centre National de Référence des Salmonella, WHO Collaborating Centre for Reference and Research on Salmonella, Paris, France
cStatens Serum Institute, Copenhagen, Denmark
dWHO National Salmonella and Shigella Center, National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand

Category B bioterrorism pathogens are the second highest priority organisms/biological agents. They are moderately easy to disseminate, result in moderate morbidity rates and low mortality rates and require specific enhancements for diagnostic capacity and enhanced disease surveillance

These pathogens include Food safety threats: (Salmonella species, E coli O157:H7, Shigella, Staphylococcus aureus).  Category B agents are bacteria and viruses that cause only mild disease to humans, or are difficult to contract via aerosol in a lab setting,.

See also: WHO Biosafety and Laboratory Biosecurity Program

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