Markus, S. | bioRxiv Science

bioRxiv2025

Stress tolerance of multiple Salmonella enterica strains associated with foodborne outbreaks

Salmonella enterica is a foodborne pathogen commonly found in food processing environments. While control methods such as heat treatment and sanitizers are often used, S. enterica has evolved strategies for survival and persistence to overcome pathogen control. This study assessed 43 outbreak-associated (OA) and non-outbreak associated (NOA) S. enterica isolates from serovars Enteritidis, Heidelberg, Newport, Typhimurium, and monophasic Typhimurium (I 4,[5],12:i:-) for enhanced stress tolerance. Heat shock at 56{degrees} C, minimum inhibitory concentrations (MICs) for sanitizers sodium hypochlorite (NaOCl) and peracetic acid (PAA), and crystal violet microtiter assays were used to evaluate heat tolerance, sanitizer tolerance, and attachment capacity, respectively. Most isolates (n =34/43) carried at least one antimicrobial resistance gene, and nearly half (n =21/43) displayed genotypic and/or phenotypic resistance to ampicillin, ciprofloxacin, or ceftriaxone. Most isolates carried genes conferring resistance to gold (n =43/43) and arsenic (n= 41/43), and tolerance to mercury, copper, and silver was common among monophasic Typhimurium and Heidelberg isolates. Efflux pump qacEdelta1 was detected among eight Heidelberg isolates. We found enhanced stress tolerance (i.e. an unusually high ability to survive and adapt to various environmental stresses) to sanitizers and enhanced attachment capacity, indicating biofilm formation. Isolates evaluated for heat tolerance survived at least 15 min at 56{degrees} C and three survived >60 min. Overall, we found evidence of enhanced tolerance to individual stresses across both OA and NOA S. enterica. There were no strong patterns based upon serovar or OA/NOA status; however, we did find that specific enhanced stress tolerance profiles may have contributed to outbreak characteristics.

microbiology↗

bioRxiv2018

Incomplete penetrance for isolated congenital asplenia in humans with mutations in translated and untranslated RPSA exons

Isolated congenital asplenia (ICA) is the only known human developmental defect exclusively affecting a lymphoid organ. In 2013, we showed that private deleterious mutations in the protein-coding region of RPSA, encoding ribosomal protein SA, caused ICA by haploinsufficiency with complete penetrance. We reported seven heterozygous protein-coding mutations in 8 of the 23 kindreds studied, including 6 of the 8 multiplex kindreds. We have since enrolled 33 new kindreds, 5 of which are multiplex. We describe here eleven new heterozygous ICA-causing RPSA protein-coding mutations, and the first two mutations in the 5-UTR of this gene, which disrupt mRNA splicing. Overall, 40 of the 73 ICA patients (55%) and 23 of the 56 kindreds (41%) carry mutations located in translated or untranslated exons of RPSA. Eleven of the 43 kindreds affected by sporadic disease (26%) carry RPSA mutations, whereas 12 of the 13 multiplex kindreds (92%) carry RPSA mutations. We also report that six of eighteen (33%) protein-coding mutations and the two (100%) 5-UTR mutations display incomplete penetrance. Three mutations were identified in 2 independent kindreds, due to a hotspot or a founder effect. Lastly, RPSA ICA-causing mutations were demonstrated to be de novo in 7 of the 23 probands. Mutations in RPSA exons can affect the translated or untranslated regions and can underlie ICA with complete or incomplete penetrance.

genetics↗