Background:  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 in South 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.

NCBI PD link for serovar Johannesburg: https://www.ncbi.nlm.nih.gov/pathogens/isolates/#(taxgroup_name:%22Salmonella%20enterica%22)%20AND%20computed_types:(%22serotype=Johannesburg%22)

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 outbreaks:

Year

Location

Associated source

Number of cases

2024US: multistateBackyard poultry1470
2011US: multistateChicks and ducklings28
1974China: Hong KongHospital-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

2020PolandSlovakiaMinced meat preparationMeat and meat products (other than poultry)

Recalls:

YearLocationRecalled foodType
2021GermanyTiger nut flourOther food product / mixed

Relevant links:

  1. https://www.cabidigitallibrary.org/doi/full/10.5555/19532201465
  2. https://journals.asm.org/doi/10.1128/aem.07015-11
  3. https://www.sciencedirect.com/science/article/pii/S016344530090762X?via%3Dihub
  4. https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1547190/full
  5. https://www.mdpi.com/2076-2607/12/4/669
  6. https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-128-2-239
  7. https://pmc.ncbi.nlm.nih.gov/articles/PMC1320082/
  8. https://www.cdc.gov/salmonella/outbreaks/backyardpoultry-05-24/investigation.html
  9. https://archive.cdc.gov/www_cdc_gov/salmonella/2011/chicks-ducklings-10-6-2011.html#:~:text=Outbreak%20Summary&text=The%20first%20was%20an%20outbreak,had%20a%20similar%20geographic%20distribution.
  10. https://pmc.ncbi.nlm.nih.gov/articles/PMC2129741/
  11. https://webgate.ec.europa.eu/rasff-window/screen/notification/444589
  12. https://webgate.ec.europa.eu/rasff-window/screen/notification/512070
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