S. Johannesburg¶

At a Glance


Antigenic Formula	`1,40:b:e,n,x`
Serogroup	O:40 (R)
NCBI Pathogen Detection	View isolates

Background Information¶

Salmonella enterica subsp. enterica serovar Johannesburg (antigenic formula: 1,40:b:e,n,x) is a serovar of the O:40 (R) serogroup. This serovar was first isolated inSouth Africa in 1952. In a US study, serovar Johannesburg remained the most frequently isolated serotypes of the 9 serotypes detected from chilled final carcasses in pork processing plants. This serovar was reported to cause septic deep vein thrombosis.

Genetic Characteristics¶

Serovar Johannesburg has been found to be paraphyletic. A non-Johannesburg serovar, S. Urbana, clusters within serovar Johannesburg. 74.2% of Johannesburg isolates (out of 66) found in pork processing plants were MDR. Class 1 integrons were found in Johannesburg isolates. Chau et al. revealed that between 1973 and 1975, Johannesburg strains exhibiting the ASTCKSu-resistance pattern were most common, while those with the ASCKSu-resistance pattern became predominant from 1976 to 1979. These resistance traits were mediated by autotransferring plasmids of the incompatibility group FI me. The ASTCKSu-resistance plasmids were highly unstable, generating deletion variants at a significantly higher rate than ASCKSu-resistance plasmids—whether naturally occurring or derived in vitro from ASTCKSu-resistance plasmids suggesting that the ASCKSu-resistance plasmid could be a deletion variant of the ASTCKSu-resistance plasmid.

Animal Reservoir¶

Unknown, chicken tends to be a potential reservoir for serovar Johannesburg. Based on the NCBI PD metadata, this serovar was also isolated from other animals such as pigs and cattle.

Geographical Distribution¶

This serovar was considered rare but has still been occasionally reported worldwide, such as in the US, the UK, and South Africa.

Human/Animal Outbreaks¶

Year	Location	Associated source	Number of cases
2024	US: multistate	Backyard poultry¹	470
2011	US: multistate	Chicks and ducklings	28
1974	China: Hong Kong	Hospital-associated²	46

¹ Salmonella Altona, Cerro, Enteritidis, Indiana, Infantis, Johannesburg, Mbandaka, and Typhimurium were involved.

² Suspected. No common vehicle could be identified as the source of infection.

Border Rejections¶

Year	Exporting country	Importing country	Associated source	Product category
2020	Poland	Slovakia	Minced meat preparation	Meat and meat products (other than poultry)

Recalls¶

Year	Location	Recalled food	Type
2021	Germany	Tiger nut flour	Other food product / mixed