"Does the Salmonella Genomic Island 1 (SGI1) confer invasiveness properties to human isolates?"

BACKGROUND: In the eighties, a multidrug resistant clone of Salmonella Typhimurium DT104 emerged in UK and disseminated worldwide. This clone harbored a Salmonella genomic island 1 (SGI1) that consists of a backbone and a multidrug resistant region encoding for penta-resistance (ampicillin, chloramphenicol/florfenicol, streptomycin/spectinomycin, sulphonamides and tetracycline (ACSSuT)). Several authors suggested that SGI1 might have a potential role in enhancement of virulence properties of Salmonella enterica. The aim of this study was to investigate whether nontyphoidal S. enterica isolates carrying SGI1 cause more severe illness than SGI1 free ones in humans. METHODS: From 2011 to 2016, all patients infected with nontyphoidal S. enterica in our hospital were retrospectively included. All nontyphoidal S. enterica isolates preserved in our University Hospital (Dijon, France) were screened for the presence of SGI1. Clinical and biological data of patients were retrospectively collected to evaluate illness severity. Statistical analysis of data was performed by Kruskal-Wallis test or Fisher's exact test for univariate analysis, and by logistic regression for multivariate analysis. RESULTS: A total of 100 isolates of S. enterica (22 serovars) were collected. Twelve isolates (12%) belonging to 4 serovars harbored SGI1: S. Typhimurium, S. Infantis, S. Kentucky, S. St Paul. The severity of the disease was age-related (for invasive infection, sepsis and inflammatory response) and was associated with immunosuppression (for invasive infection, sepsis and bacteremia) but not with the presence of SGI1 or with antimicrobial resistance. CONCLUSION: A rather high proportion (12%) of human clinical isolates belonging to various serovars (for the first time serovar St Paul) and harboring various antimicrobial resistance profile carried SGI1. Diseases due to SGI1-positive S. enterica or to antimicrobial resistant isolates were not more severe than the others. This first clinical observation should be confirmed by a multicenter and prospective study.

Study of 109 Achromobacter spp. isolates from 9 French CF centres reveals the circulation of a multiresistant clone of A. xylosoxidans belonging to ST 137.

We previously reported the distribution of Achromobacter spp. (species and Sequence Types (ST)) in our French Cystic Fibrosis (CF) centre. In the present study we collected 109 Achromobacter isolates (1/patient) from 9 other French CF Centres for species identification, antimicrobial susceptibility testings and Multilocus-Sequence-Typing (MLST) analysis. Ten species were detected, A. xylosoxidans being the most predominant one (73.4% of the isolates). Piperacillin-tazobactam, ceftazidime, imipenem, meropenem and ciprofloxacin were respectively active against 88, 70, 79, 72 and 23% of the isolates. Among the 79 A. xylosoxidans isolates, 46 STs were detected. Interestingly, ST 137, recovered in 4 centres (5 patients), was previously detected in our centre (2 patients). The strains from the 7 patients belonged to the same pulsotype (pulsed-field-gel-electrophoresis analysis) and harboured acquired resistance to meropenem, ceftazidime, ciprofloxacin, and except for 2 isolates, to imipenem and piperacillin-tazobactam. This is the first description in France of a circulating multiresistant A. xylosoxidans strain.