Researchers have found epidemiologic and genomic evidence that the meat-production chain is a possible major source of Staphylococcus saprophyticus causing human urinary tract infections.

The study titled, “Foodborne Origin and Local and Global Spread of S. saprophyticus Causing Human Urinary Tract Infections,” provides insight into the origin, transmission, and population structure of pathogenic S. saprophyticus and identifies possible new virulence factors.

S. saprophyticus is a Gram-positive bacterium that is a common cause of urinary tract infections, especially in young females. It is also found in pigs and cows and may be a source of human gut colonization and human S. saprophyticus infection through transferred contamination of meat by the meat-processing chain.  S. saprophyticus UTIs have a  greater successful treatment rate than  Escherichia coli UTIs, but they also have a  higher recurrent infection frequency. Rare complications of S. saprophyticus UTI include acute pyelonephritis, nephrolithiasis, and endocarditis.

The researchers, led by  Opeyemi U. Lawal a postdoctoral researcher at the Instituto de Tecnologia Quimica e Biologica, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal, conducted a phylogenomic analysis of 321 S. saprophyticus isolates collected from human UTIs worldwide during 1997–2017 and 232 isolates from human UTIs and the pig-processing chain in a confined region during 2016–2017. 

The study used phenotypic, genomic, and pangenome-wide association study (pan-GWAS) approaches to characterize S. saprophyticus both globally and locally. In addition, the researchers identified adaptive features that drive S. saprophyticus evolution, defined the S. saprophyticus population structure, investigated dissemination routes and identified new pathogenicity factors.