S. Worthington¶

At a Glance


Antigenic Formula	`1,13,23:z:l,w`
Serogroup	O:13 (G)
NCBI Pathogen Detection	View isolates

Background Information¶

Salmonella enterica subsp. enterica serovar Worthington (antigenic formula 1,13,23:z:l,w) is a serovar of the O:13 (G) serogroup. Serovar Worthington was first isolated in 1937from a young turkey and a chick by Dr. Pomeroy. The serovar was named after Worthington, Minnesota, the location of the hatchery that raised the birds carrying the original isolates. Serovar Worthington was the 2^nd most common nontyphoidal Salmonella serovar isolated from human infections in India during 2001-2005.

The most common source of serovar Worthington is turkey, and its production environment. This serovar has been reported in milk powder, vegetables, and seafood. However, serovar Worthington has been frequently reported to cause infection especially in neonatal cases and pediatric wards. Serovar Worthington tends to cause infection in vulnerable groups such as newborns or elderly. Although the symptoms caused by serovar Worthington infection are likely non-typhoidal infection symptoms such as diarrhea or vomiting, in some cases, it can develop to meningitis leading to death. In 1955, there was a report on serovar Worthington suspected causing gastroenteritis including vomiting from artificial feeding in several newborn babies in a small maternity ward in an Indonesian hospital. Another outbreak involving newborn babies occurred in a hospital in Hong Kong in August 1974 leading 13 cases, including 1 death due to meningitis; at the time, the outbreak source was not identified. Five weeks later, five newborns were infected with the same serovar, and in this instance it was found that the outbreak was caused by contamination in the tubing system of a suction apparatus, which was used for baby's oropharyngeal suction. Another outbreak in Pakistan in early 1990s was also linked to contamination of newborn oropharyngeal suction apparatus; Salmonella Worthington was recovered from 18 babies who received suction. Recently, serovar Worthington has been found to be multidrug-resistant, challenging the treatment especially in neonates and elderly.

Genetic Characteristics¶

Serovar Worthington has been found to be polyphyletic with one lineage identified and one stand-alone singleton that does not cluster with any other Salmonella Worthington isolates. Salmonella Worthington isolates from preharvest turkey production sources pose both virulence and persistence by carrying virulence genes, such as invA, aceK, and sopB, along with resistance to many antibiotics (tetracycline, erythromycin, bacitracin, novobiocin, and rifampin). Salmonella Worthington has been reported as having acquired the third-generation cephalosporin resistance plasmid (bla_DHA-1-carrying IncFII plasmid) from Citrobacter amalonaticus.

Animal Reservoir¶

Serovar Worthington has been commonly found in turkeys including their environments.

Geographical Distribution¶

Serovar Worthington has been found in the United States, Indonesia, Hong Kong, India, Thailand, and Pakistan.

Human/Animal Outbreaks¶

Several human outbreaks have been associated with S. Worthington. Below are some examples.

Year	Location	Associated source	Number of cases
2012	US-multistate	Mangoes	16
2005	France	Milk powder	49
2000	India	No source or carrier identified	16
1975	Hong Kong	Tubing system of a suction apparatus	18
1955	Indonesia	Artificial feeding¹	154

¹ Because of limitation of serological procedure at that time, this outbreak might be caused by pathogenic E. coli or Salmonella Worthington or both organisms

Border Rejections¶

One case of border rejections associated with serovar Worthington was reported.

Year	Exporting country	Importing country	Associated source	Product category
2022	USA via Lithuania	Finland	Salted and roasted pistachios	Nuts, nut products and seeds

Recalls¶

One recall linked to serovar Worthington has been reported.

Year	Location	Recalled food	Type
2012	US: multistate	Mangoes¹	Fruit

¹ This recall was caused by a multistate outbreak. Daniella brand mangoes grown in Mexico were recalled.