Comparison of Phenotype and Genotype Virulence and Antimicrobial Factors of Salmonella Typhimurium Isolated from Human Milk

Abstract

Salmonella is a common foodborne infection. Many serovars belonging to Salmonella enterica subsp. enterica are present in the gut of various animal species. They can cause infection in human infants via breast milk or cross-contamination with powdered milk. In the present study, Salmonella BO was isolated from human milk in accordance with ISO 6579-1:2017 standards and sequenced using whole-genome sequencing (WGS), followed by serosequencing and genotyping. The results also allowed its pathogenicity to be predicted. The WGS results were compared with the bacterial phenotype. The isolated strain was found to be Salmonella enterica subsp. enterica serovar Typhimurium 4:i:1,2_69M (S. Typhimurium 69M); it showed a very close similarity to S. enterica subsp. enterica serovar Typhimurium LT2. Bioinformatics sequence analysis detected eleven SPIs (SPI-1, SPI-2, SPI-3, SPI-4, SPI-5, SPI-9, SPI-12, SPI-13, SPI-14, C63PI, CS54_island). Significant changes in gene sequences were noted, causing frameshift mutations in yeiG, rfbP, fumA, yeaL, ybeU (insertion) and lpfD, avrA, ratB, yacH (deletion). The sequences of several proteins were significantly different from those coded in the reference genome; their three-dimensional structure was predicted and compared with reference proteins. Our findings indicate the presence of a number of antimicrobial resistance genes that do not directly imply an antibiotic resistance phenotype.

Salmonella pathogenicity island-14 is a critical virulence factor responsible for systemic infection in chickens caused by Salmonella gallinarum

“…The functions of SPIs have been mainly studied in gastrointestinal pathogenic bacteria, such as S. typhimurium and S. enteritidis , that have a wide range of hosts and cause self-limited diarrhea in humans and animals ( 7 , 9 , 25 ). SPIs have important effects on the bacterial physiology and interactions with the environment and gastrointestinal tract of mammals ( 7 , 26 ).…”

“…Additionally, LoiA can also regulate multiple virulence-related genes in S. typhimurium through the negative regulation of Lon protease ( 29 ). Recent studies have demonstrated that S. enteritidis and S. typhimurium may share the same virulence mechanisms for epithelial cell invasion and survival within macrophages ( 9 , 25 , 30 ).…”

Molecular Identification and Characterization of Salmonella Sp. In Raw and Heat-Treated Milks from Local Market

“…as containing unique sequences to the genus Salmonella. In addition, SifA gene, located in chromosome, decrease of kinesin accumulation in the SCV, modulation of vesicular trafficking, SCV perinuclear migration, SCV membrane integrity and SipA, located in SPI-1, Actin Stabilization and localization of actin filaments during invasion, stabilization of VAP, correct localization of SifA and PipB2, SCV perinuclear migration and morphology (Shalal et al, 2023;Maaroof and Dhayea, 2023;Pławińska-Czarnak et al, 2023;Yuliangsih et al, 2019).…”