84 research outputs found
Measles in Italy: Viral strains and crossing borders
In 2017, Italy experienced one of the largest outbreaks of measles in recent years, with 5404 notified cases and 4347 confirmed cases. A further 2029 cases were notified during the first 6 months of 2018, and 1516 of them were laboratory-confirmed. The B3 and D8 genotypes were identified as those responsible for the outbreak. Possible transmission routes can be established by monitoring the circulating measles virus strains in support of the national health authorities to warn people and travellers
Emerging resistance mechanisms in ESBL-producing strains
Objective: ESBL producing strains are increasingly reported to present
additional resistance mechanisms. These multidrug resistant strains
should be detected early to rationalize drug treatment and avoid increased
selection of resistance. The aim of this study was to detect the
presence of AmpC, carbapenemases and plasmid-mediated quinolone
resistance (PMQR) (qnr, aac(6)-Ib-cr and qepA) mechanisms in ESBLproducing
strains by genotypic assays and compare their efficiency
versus phenotypic methods.
Methods: ESBL- and AmpC-producing strains were identified by
the double-disk test and double disk synergy test, respectively.
Carbapenemases were phenotypically detected by the Hodge test. MIC
of fluoroquinolones was detected by Etest. AmpC, carbapenemase, qnr,
aac(6)-Ib-cr and qepA genes were identified by multiplex PCR and
sequencing. Topoisomerase II mutations were detected by sequencing
of the quinolone-resistant determining region.
Results: In 2009, 200 ESBL-producing Enterobacteriaceae isolates
were collected at the Microbiology Unit of the Padua Hospital. ESBL
belonging to different classes (TEM, SHV, CTX-M and OXA) were
characterized by genotypic analysis. Qnr and aac(6)-Ib-cr genes were
found in 26% and 8% isolates, respectively. Qnr was mostly present
in Klebsiella pneumoniae, while aac(6)-Ib-cr was found exclusively
in Escherichia coli. QepA was not found. Both genes were localized
on plasmids and could be both transformed and trans-conjugated in
acceptor strains. MIC of fluoroquinolones on these acceptor strains
indicated a 20\u2013100 increased resistance due to the plasmid-mediated
mechanism. However, high-level resistance to fluoroquinolone in the
wild-type strains was due to the additional presence of topoisomerase
mutations in strains presenting both ESBL and PMQR. AmpC were
detected on 5.5% isolates of Enterobacter spp. and Proteus mirabilis.
Carbapenemases were found in 3% isolates of E. aerogenes, E. coli
and K. pneumoniae. Carbapenemases were subsequently genotypically
characterized as IMP, VIM, OXA, KPC CMY or SME types.
Conclusions: Emerging resistance mechanisms were found in ESBLproducing
strains, with PMQR being the most frequent. While genotypic
assays implement phenotypic testing of AmpC and carbapenemases, they
are the only methods available up to date for detection of PMQR. Hence,
both phenotypic and genotypic methods should be employed to rationally
direct the pharmacological treatment
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