1. Persistent Infections by Nontyphoidal Salmonella in Humans: Epidemiology and Genetics
- Author
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Marzel, Alex, Desai, Prerak T, Goren, Alina, Schorr, Yosef Ilan, Nissan, Israel, Porwollik, Steffen, Valinsky, Lea, McClelland, Michael, Rahav, Galia, and Gal-Mor, Ohad
- Subjects
Human Genome ,Biodefense ,Genetics ,Infectious Diseases ,Digestive Diseases ,Prevention ,Foodborne Illness ,Vaccine Related ,Emerging Infectious Diseases ,Aetiology ,2.2 Factors relating to the physical environment ,2.1 Biological and endogenous factors ,Infection ,Adolescent ,Adult ,Aged ,Animals ,Child ,Child ,Preschool ,Chronic Disease ,DNA ,Bacterial ,Disease Models ,Animal ,Female ,Genome ,Bacterial ,Humans ,Infant ,Israel ,Male ,Mice ,Retrospective Studies ,Salmonella Infections ,Salmonella enterica ,Sequence Analysis ,DNA ,Young Adult ,salmonellosis ,persistent infection ,WGS ,epidemiology ,Biological Sciences ,Medical and Health Sciences ,Microbiology - Abstract
BackgroundAlthough chronic infections by typhoidal Salmonella are well-known, prolonged human infections by nontyphoidal Salmonella (NTS) are poorly characterized.MethodsWe retrospectively analyzed 48 345 culture-confirmed NTS infections that occurred in Israel 1995-2012. A case-control study was performed to identify risk factors associated with persistent infections. Whole-genome-sequencing, pulsed-field gel electrophoresis (PFGE), and a mouse infection model were used to study genetic and phenotypic differences between same-patient persistent, recurring isolates.ResultsIn total, 1047 cases of persistent NTS infections, comprising 2.2% of all reported cases of salmonellosis, were identified. The persistence periods ranged between 30 days to 8.3 years. The majority (93%) of the persistently infected patients were immunocompetent, and 65% were symptomatic with relapsing diarrhea, indicating a distinct clinical manifestation from the asymptomatic carriage of typhoidal Salmonella. Four NTS serovars (Mbandaka, Bredeney, Infantis and Virchow) were found to be significantly more frequently associated with persistence than others. Comparative genomics between early and later isolates obtained from the same patients confirmed clonal infection and showed 0 to 10 SNPs between persistent isolates. A different composition of mobile genetic elements (plasmids and phages) or amino acid substitutions in global regulators was identified in multiple cases. These changes resulted in differences in phenotype and virulence between early and later same-patient isolates.ConclusionsThese results illuminate the overlooked clinical manifestation of persistent salmonellosis that can serve as a human reservoir for NTS infections. Additionally, we demonstrate mechanisms of in-host microevolution and exhibit their potential to shape Salmonella pathogenicity, antimicrobial resistance and host-pathogen interactions.
- Published
- 2016