S. Mbandaka¶

At a Glance


Antigenic Formula	`6,7,14:z10:e,n,z15`
Serogroup	O:7 (C1)
NCBI Pathogen Detection	View isolates

Background Information¶

Salmonella enterica subsp. enterica serovar Mbandaka (antigenic formula 6,7,14:z₁₀:e,n,z₁₅) is a serovar of the O:7 (C₁) serogroup. This serovar was first isolated in 1948 from a human salmonellosis case in the Belgian Congo. Serovar Mbandaka was ranked among thetop 10 serovars responsible for human salmonellosis cases in Europe. This serovar was also among the 20 most prevalent serovars associated with human cases in other countries, along with Israel, North America, Africa, and New Zealand. In a Chinese pig farm, serovar Mbandaka (12.6%) ranked as the fourth most prevalent serovar identified. In nine broiler slaughterhouses in Brazil, serovar Mbandaka (12.7%) was the third most frequent serovars isolated. This serovar was reported to cause travel-associated sacroiliac osteomyelitis in a healthy adolescent.

Genetic Characteristics¶

Serovar Mbandaka has been found to be polyphyletic with one lineage identified and one stand-alone singleton that does not cluster with any other Salmonella Mbandaka isolates. A Canadian study using CRISPR-SeroSeq on Ontario poultry farms found that spacer reads could not distinguish between serovars Montevideo and Mbandaka. Antony et al. included more than 400 serovar Mbandaka isolates in their study and found two major groups with no pattern identified based on host or geographical origin. Additionally, they reported that a uniform virulence gene profile in all serovar Mbandaka isolates. Their phenotypic analysis revealed a similar trend in adaptation to a low pH environment and cell invasion behavior using a representative set of isolates. Among 403 Mbandaka genomes, resistance to tetracycline (16.87%) was the most common, followed by aminoglycosides (13.89%), sulfonamide (8.4%), QAC (6.9%), trimethoprim (5.7%), and quinolone (3.47%). The tetracycline resistance gene tet(B) was the most common (10.66%), followed by the aminoglycoside resistance genes aph(6)-Id (8.93%) and aph(3'')-Ib (8.68%). Hayward et al. revealed that Salmonella pathogenicity island 23 was found in several serovars, including Salmonella Agona, Dublin and Gallinarum, but it is absent in Salmonella Mbandaka. In Poland, serovar Mbandaka carrying the bla_CTX-M-8 gene located on IncI1 plasmid was isolated from a broiler farm. Some Mbandaka isolates exhibited resistance to multiple drugs. For instance, in a Brazilian study, all 6 Mbandaka isolates carried aac(6′)-Iaa (amikacin/tobramycin resistance), while aadA1 (spectinomycin), sul1 (sulfonamides), dfrA variants (trimethoprim), and tetB (tetracycline) were detected in 4–5 of 6 isolates.

Animal Reservoir¶

Chicken is the main reservoir for serovar Mbandaka. This serovar was also isolated from other animals (pigs, cattle, fish, wild birds, and canine).

Geographical Distribution¶

Serovar Mbandaka has been reported worldwide.

Human/Animal Outbreaks¶

Numerous outbreaks in different countries have been linked to serovar Mbandaka, imported spices have been associated with several of these outbreaks. Below are some examples.

Year	Location	Associated source	Number of cases
2024	US: multistate	Backyard poultry¹	470
2021-2024	Europe: multi-country	Frozen steam-cooked chicken breast, produced in Ukraine²	300
2021	US: ME	Pad thai	129
2018	US: multistate	Honey smack cereal	135
2013	US: multistate	Tahini³	16
2013	US: multistate	Live poultry⁴	158
2008–2019	US: MI	Restaurant-related	36

¹ Multiple serovars, including Salmonella Altona, Cerro, Enteritidis, Indiana, Infantis, Johannesburg, Mbandaka, and Typhimurium, were linked to this outbreak. The case number represents the total number of cases associated with the outbreak and does not specifically indicate the number of people infected by Salmonella Mbandaka.

² Salmonella Mbandaka ST413 was the outbreak strain. A total of 300 cases were reported by March 15th, 2024.

³ A total of 16 cases with the outbreak strains of Salmonella Montevideo (four persons) or Salmonella Mbandaka (12 persons) were reported from nine states.

⁴ Salmonella Infantis, Lille, Newport, and Mbandaka were involved in this outbreak. The case number represents the total number of cases associated with the outbreak and does not specifically indicate the number of people infected by Salmonella Mbandaka.

Border Rejections¶

Multiple border rejections linked to serovar Mbandaka have been reported. Below are some examples.

Year	Exporting country	Importing country	Associated source	Product category
2024	Belarus	Poland	Rapeseed extraction meal	Feed materials
2024	China	Italy	Chili pepper (Capsicum annum)	Herbs and spices
2023	Hungary	Germany	Onion powder¹	Other food product / mixed
2021	Chile	Sweden	Dried oregano	Herbs and spices

¹ Salmonella Agona, Idikan, Richmond, Falkensee, Molade, Mbandaka and Senftenberg were found.

Recalls¶

Multiple recalls linked to serovar Mbandaka have been reported. Below are some examples.

Year	Location	Recalled food	Type
2024	Finland	Beef sirloin steak from Germany	Meat and meat products (other than poultry)
2024	Germany	Tahini sesame paste from Egypt, via France	Nuts, nut products and seeds
2023	Germany	Helva with vanilla flavor from Turkey	Confectionery
2023	Germany	Tahini from Turkey, with raw material from Nigeria	Nuts, nut products and seeds
2022	Germany	Sesame paste from Syria	Cereals and bakery products
2018	US: multistate	Honey smacks cereal¹	Cereals and bakery products

¹ This recall was resulted by a multistate outbreak described above. Kellogg company voluntarily recalled their 15.3 oz. and 23 oz. packages of honey smacks cereal.