Bacterial Whole Genome Sequencing in Investigation of Salmonella Oranienburg Infection Outbreak, Missouri, USA

George T,Autumn G,Perkins A,Ashley M,Jenell L,Rachel H,Virginia P,Luebbering L,Lina C,John B,Ann W,Cindy B,Crystal T,Meller J

doi:10.4172/1989-8436.100059

Abstract

Background: In April 2015, the Missouri Department of Health and Senior Services identified a cluster of four Salmonella enterica serovar Oranienburg infections among residents of the St. Louis metro area. Clinical isolates from those patients shared an indistinguishable pulsed-field gel electrophoresis (PFGE) pattern. Methods and Findings: The ensuing outbreak investigation included epidemiological, laboratory, and environmental investigations. Clinical and environmental isolates were subtyped by PFGE pattern and whole genome sequencing (WGS). Eggs from a single poultry farm and processing facility were identified as the likely source of this outbreak based on the epidemiologic data, highly related Salmonella isolates from the farm and processing facility, and clinical isolates from patients. The egg farm operations were suspended, and the producer issued a voluntary recall of all eggs produced up to the time of the recall. Conclusions: WGS is a valuable tool for Salmonella Oranienburg infection outbreak investigation. Early prospective application of WGS enhances several aspects of the outbreak investigation. A thorough analysis of combined epidemiological, traceback, and advanced molecular laboratory data is needed for the proper management of foodborne outbreak investigation.

Highlights

In April 2015, the Missouri Department of Health and Senior Services (MDHSS) identified a cluster of four Salmonella enterica serovar Oranienburg infections among residents of the St
The outbreak pulsed-field gel electrophoresis (PFGE) pattern was historically rare in Missouri with only seven cases reported before 2015
A multi-state outbreak case was defined as illness in a person who was a resident of or who had known travel to Missouri and was infected with Salmonella serovar Oranienburg, with an isolate matching PFGE Xbal pattern JJXX01.0027 or JJXX01.1185, or illness in a person outside Missouri infected with Salmonella Oranienburg with isolate matching PFGE XbaI pattern JJXX01.0027 and highly related to outbreak isolates by whole genome sequencing (WGS)

Summary

Introduction

In April 2015, the Missouri Department of Health and Senior Services (MDHSS) identified a cluster of four Salmonella enterica serovar Oranienburg infections among residents of the St. Louis metro area. Serovar Oranienburg outbreaks were associated with a variety of food items, including German chocolate [2], fruit salad [3], black pepper [4], and chia powder [5]. While investigating this cluster, the MDHSS was notified by the PulseNet at the Center for Disease Control and Prevention (CDC), Atlanta, GA, USA, of the same Salmonella. Clinical isolates from those patients shared an indistinguishable pulsed-field gel electrophoresis (PFGE) pattern

Methods

Results

Discussion

Conclusion