41 Decline in AmpC beta-lactamase-producing E. coli in a Dutch teaching hospital region associated with cAmpC hyperproduction (Tracz et al. 2007). Moreover, none of the pAmpC producing isolates (n = 19) showed mutations that are associated with cAmpC hyperproduction. One isolate could not be amplified using Sanger sequencing technique and was negative in Micro-array which was therefore considered as inconclusive. An overview of all alterations in the promoter/attenuator region as well as MIC values for cefotaxime, ceftazidime and cefoxitin can be found in the additional S1 Table. In 2013, two blaCMY-2-like producing E. coli isolates from two patients were confirmed to have the same AFLP pattern. Three cAmpC producing E. coli (all Mulvey Type 3) from three different patients in 2014 showed a similar AFLP pattern as well. AFLP patterns can be found in the additional data S1 Fig. A declining trend was seen in the overall prevalence of AmpC in E. coli isolates using Mantel-Haenzsel test for linear association (p = 0.006). When probable genetically related AmpC isolates based upon AFLP were excluded the decline was still significant. The decrease was only significant for cAmpC hyperproducers (p = 0.012) and not for pAmpC (p = 0.287) (Figs 1 and 2). A univariable and multivariable logistic regression analysis was performed on the cAmpC rectal carriage prevalence over the four-year period (2013–2016) adjusted for gender (univariate analysis, p = 0.15) (see supplementary data, S2 Table). Figure 1. Prevalence of cAmpC hyperproducing E. coli from 2013 to 2016 with 95% confidence interval. 3
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