Pan-Genome-Wide Association Study reveals a key role of the salmochelin receptor IroN in the biofilm formation of Salmonella Typhimurium and its monophasic variant 4,[5],12:i:.

Salmonella enterica subsp. enterica serovar Typhimurium variant 4,[5],12:i:- (so called S. 4,[5],12:i:-) has rapidly become one of the most prevalent serovars in humans in Europe, with clinical cases associated with foodborne from pork products. The mechanisms, genetic basis and biofilms relevance by which S. 4,[5],12:i:- maintains and spreads its presence in pigs remain unclear. In this study, we examined the genetic basis of biofilm production in 78 strains of S. 4,[5],12:i:- (n = 57) and S. Typhimurium (n = 21), from human gastroenteritis, food products and asymptomatic pigs. The former showed a lower Specific Biofilm Formation index (SBF) and distant phylogenetic clades, suggesting that the ability to form biofilms is not a crucial adaptation for the S. 4,[5],12:i:- emerging success in pigs. However, using a pan-Genome-Wide Association Study (pan-GWAS) we identified genetic determinants of biofilm formation, revealing 167 common orthologous groups and genes associated with the SBF. The analysis of annotated sequences highlighted specific genetic deletions in three chromosomal regions of S. 4,[5],12:i:- correlating with SBF values: i) the complete fimbrial operon stbABCDE widely recognized as the most critical factor involved in Salmonella adherence; ii) the hxlA, hlxB, and pgiA genes, which expression in S. Typhimurium is induced in the tonsils during swine infection, and iii) the entire iroA locus related to the characteristic deletion of the second-phase flagellar genomic region in S. 4,[5],12:i:-. Consequently, we further investigated the role of the iro-genes on biofilm by constructing S. Typhimurium deletion mutants in iroBCDE and iroN. While iroBCDE showed no significant impact, iroN clearly contributed to S. Typhimurium biofilm formation. In conclusion, the pan-GWAS approach allowed us to uncover complex interactions between genetic and phenotypic factors influencing biofilm formation in S. 4,[5],12:i:- and S. Typhimurium.

Multicentre evaluation of Erytra Eflexis®, a benchtop fully automated analyser with a compact design for routine use in blood transfusion laboratory.

OBJECTIVES: Evaluation of the compact benchtop Erytra Eflexis® automated analyser was performed at three health centres representing a range of routine transfusion workload. BACKGROUND: Automation instruments with the simplicity and flexibility adequate for small- to mid-sized blood transfusion services are an unmet need. METHODS: Performance in pre-transfusion testing (2109 ABO/D, 382 Rh/K phenotype, 2001 antibody screening, 113 antibody identification, 151 DAT, 88 extended phenotype; 655 cross matching) in comparison to Erytra® as reference device was assessed. Throughput [time to first result (TTFR), final turn-around time (TAT), processing rate] was calculated; usability and adaptability in laboratory practice under routine and with emergency samples were surveyed. RESULTS: Agreement between systems was 99·8% (11/5499 test discrepancies, all due to weak/doubtful positive reactions). Erytra Eflexis produced six true positives (two Rh/D, two B positives, two screening), four false positives (three screening and one cross matching) and one false negative (screening). Processing of eight routine samples with the Erytra Eflexis for ABO/Rh(D) and screening took 34-38 min and 32-37 min, respectively, independent of the simultaneous processing of a STAT sample, whether or not the incubator for STAT was reserved. In this scenario, a STAT sample requested within 2 min after the routine load was processed in 14-26 min. Processing rate tended to stabilise and optimise in the larger workloads, particularly in ABO/Rh(D)/K cards (16·7, 18 and 19·5 results/h for 10, 15 and 24 specimens, respectively). CONCLUSION: Erytra Eflexis analyser was found to be reliable and suitable for pre-transfusion routine tests performed in a small-/medium-sized blood transfusion laboratory.