S. Saintpaul¶

At a Glance


Antigenic Formula	`1,4,[5],12:e,h:1,2`
Serogroup	O:4 (B)
NCBI Pathogen Detection	View isolates

Background Information¶

Salmonella enterica subsp. enterica serovar Saintpaul (antigenic formula 1,4,[5],12:e,h:1,2) is a serovar of the O:4 (B) serogroup. In 1940, serovar Saintpaul was first isolated from turkey in US. Enter-Net surveillance data from European national reference centers revealed serovar Saintpaul as the fourth most prevalent Salmonella serovar (1.6%) in human isolates during Q4 2006, marking a notable increase in its role as a cause of human salmonellosis compared to previous years. Subsequent surveillance showed declining prevalence, with the serovar accounting for 1.2% and 0.6% of human Salmonella infections in Q1 2007 and Q1 2008, respectively. Salmonella Saintpaul was frequently listed as top 20 Salmonella serovars in humans in Oceania and North America. A case of testicular seminoma complicated by serovar Saintpaul-induced testicular abscess has been reported.

Genetic Characteristics¶

Chen et al. found that serovar Saintpaul appeared to be polyphyletic with four distinct phylogenetic groups identified. Within serovar Saintpaul, the comparative genomic analysis revealed 384 and 619 genes enriched in isolates from 5 human-associated (HA) and 4 non-human-associated (NHA) SNP clusters, respectively, that showed the strongest association with their isolation sources. This included five known HA-linked virulence genes located on Gifsy-1/Gifsy-2 prophages. Additionally, premature stop codons were more prevalent in 3 HA and 7 NHA genes. Cell culture experiments with representative strains from 4 HA and 3 NHA clusters found no increased invasion or intracellular survival capability in HA SNP clusters. However, the presence of sodCI (encoding a superoxide dismutase)—detected in 4 HA and 1 NHA clusters—correlated with enhanced survival in macrophage-like cells. In the study of worldwide population dynamics of serovar Saintpaul, Panzenhagen et al. found a total of 49 sequence types (STs), with ST-50 (787 genomes) and ST-27 (634 genomes) being the most common. All clinical isolates from South America, including PP_BR059 (isolated from a hospitalized patient in Ceará, Brazil), belonged to ST-50. Antimicrobial resistance (AMR) analysis indicated that 60% of Salmonella Saintpaul genomes had no resistance, while ST-27 contained the highest number of AMR strains. More specifically, among the 1,954 serovar Saintpaul isolates analyzed, 391 (20%) exhibited resistance genes associated with a multidrug-resistant phenotype. Additionally, seven isolates harbored the mcr-1 gene, while 17 isolates carried the CTX-M gene. They also identified separate evolutionary lineages within ST-50 and ST-27. PP_BR059 showed reduced macrophage invasion (3.82%) but notably higher survival rates inside cells at both 2 hours (68.72%) and 20 hours (25.68%) post-infection. Similarly, serovar Saintpaul carrying both bla_CTX-M-2 and mcr-9.1 isolated in chicken carcass was reported.

In Germany, a clonal line of Salmonella Saintpaul with a multidrug resistant phenotype was found in turkeys and human feces. These isolates exhibited resistance (either complete or intermediate) to ampicillin, amoxicillin-clavulanic acid, gentamicin, kanamycin, nalidixic acid, streptomycin, spectinomycin, and sulfamethoxazole, along with intermediate resistance or reduced susceptibility to ciprofloxacin and multiple third-generation cephalosporins (including ceftiofur and cefoxitin). Genotypic analysis revealed a conserved resistance pattern, featuring bla_TEM-1, aadB, aadA2, sul1, and a Ser83→Glu83 mutation in the gyrA gene. Additionally, all isolates carried a chromosomal class 1 integron harboring the aadB-aadA2 gene cassette. In an Ethiopian study, among all tested isolates (n=28), only 17.9% were pan-susceptible, while 82.1% exhibited resistance to one to three antimicrobials. All isolates remained susceptible to gentamicin, trimethoprim-sulfamethoxazole, and trimethoprim. The highest resistance was observed against oxytetracycline (82.2%), followed by chloramphenicol, neomycin, and polymyxin B (3.6% each).

Zwe and Yuk found that pre-treatment of serovar Saintpaul with ceftiofur resulted in enhanced phenotypic resistance to ceftriaxone. However, this exposure paradoxically reduced the bacterium's ability to transfer cephalosporin resistance via conjugative transfer of the bla_CTX-M-65 gene.

Animal Reservoir¶

Unknown, but turkey and swine are likely to be reservoirs for serovar Saintpaul.

Geographical Distribution¶

This serovar is globally distributed. Serovar Saintpaul ranks among the top ten most prevalent non-typhoidal Salmonella (NTS) serovars globally, causing approximately 1.6% of severe human infections despite over 1,400 known NTS serovars. Between 2011 and 2020, serovar Saintpaul was one of the 10 most frequently isolated Salmonella serovars in Brazil, accounting for 1,222 cases (0.16% of 62,030 isolates). In the Northern territory of Australia, it was the third most frequently reported serovar in 2014, representing 11% of all reported salmonellosis cases.

Human/Animal Outbreaks¶

Multiple human outbreaks associated with serovar Saintpaul have been reported, linked to a variety of commodities. Below are some examples.

Year	Location	Associated source	Number of cases
2005	UK	Unknown	25
2023	UK and Portugal	Cantaloupe melon	98 (93 in the UK and 5 in Portugal)
2016	US: Utah	Raw milk	9
2016	Australia	Mung bean sprouts	419
2013	US: multistate	Imported cucumber	84
2009	US: multistate	Raw alfalfa sprouts	235
2008	US: multistate & Canada	Jalapeño and serrano peppers from Mexico	1442
2006	Australia	Cantaloupe	115
1999	Australia	Drinking water	28
1993	Germany	Paprika & paprika-powdered potato chips¹	Estimated 1000

¹ Serovar Javiana and Rubislaw were also involved. The case number here does not reflect the total number of people only infected by Salmonella Saintpaul.

Border Rejections¶

Multiple border rejections linked to serovar Saintpaul have been reported. A majority of these border rejections were associated with black pepper imported from Brazil to Germany and identified multiple Salmonella serovars including serovar Sainpaul. Below are some examples.

Year	Exporting country	Importing country	Associated source	Product category
2023	Vietnam	Italy	Frozen raw frog legs	Meat and meat products (other than poultry)
2021	Brazil	Germany	Black pepper¹	Herbs and spices
2020	Brazil	Germany	Black pepper²	Herbs and spices
2020	Brazil	Germany	Black pepper³	Herbs and spices
2020	Germany, Netherlands	Italy	Poultry and veal kebab⁴	Meat and meat products (other than poultry)

¹ Salmonella Poona, Javiana and Saintpaul were found.

² Salmonella Infantis, Freetown, Javiana, and Saintpaul were found.

³ Salmonella Saintpaul and Javiana were found.

⁴ Salmonella Derby and Saintpaul were found.

Recalls¶

Year	Location	Recalled food	Type
2023	Spain	Fresh turkey meat	Poultry meat and poultry meat products
2008	US: multistate	Jalapeno peppers¹	Fruits and vegetables

¹ This recall was caused by a multistate outbreak described above. Agricola Zaragoza, Inc. of McAllen, TX issued a recall of their Jalapeno peppers.