SummaryBackground Gaps in the diagnostic capacity and heterogeneity of national surveillance and reporting standards in Europe make it diffi cult to contain carbapenemase-producing Enterobacteriaceae. We report the development of a consistent sampling framework and the results of the fi rst structured survey on the occurrence of carbapenemaseproducing Klebsiella pneumoniae and Escherichia coli in European hospitals.

11%]). Overexpression of the natural AmpC cephalosporinase was common (42%), but only a few ST235 or ST111 isolates produced VIM-1 or VIM-2 metallo-␤-lactamases or PER-1 or GES-7 extendedspectrum ␤-lactamases.

Four NDM-1-producing Enterobacteriaceae strains (three Klebsiella pneumoniae and one Citrobacter koseri) were isolated between 2009 and 2011 through a nationwide surveillance for carbapenem-resistant Enterobacteriaceae in Croatia to study the molecular genetic background of blaNDM and the responsible plasmid types. Phenotypically, the clinical strains proved to be multidrug resistant. All strains remained susceptible to tigecycline and colistin. The clinical strains harbored variable antibiotic resistance determinants, notably, blaNDM-1, blaTEM-1, blaSHV-1, blaSHV-12, blaOXA-1, blaOXA-9, blaCTX-M-15, blaCMY-4, qnrB1, and aac(6')Ib-cr in different combinations. Two K. pneumoniae belonged to sequence type ST15 and one strain to ST16. As for the plasmid types, C. koseri and one of the ST15 K. pneumoniae carried IncR, and the second ST15 K. pneumoniae carried IncR and colE. The K. pneumoniae ST16 strain hosted A/C and colE plasmids. The blaNDM-1 gene was detected on conjugative high-molecular-weight plasmids, namely, A/C and IncR types. It is noteworthy that this is the first description of K. pneumoniae ST16 expressing NDM-1 in Europe. Remarkably, our study underscores the importance of the IncR plasmid as a reservoir of multidrug resistance. To the best of our knowledge, the IncR plasmid carrying blaNDM-1 in C. koseri is reported for the first time.

This report describes that the early stage of KPC-producing K. pneumoniae dissemination in Croatia is associated with a prolific PFGE type belonging to ST258. So far, the spread of an outbreak strain is limited to the northwest region of the country.

Here, we report a retrospective study conducted to elucidate emergence, epidemiology, and molecular mechanisms of resistance underlying the early spread of OXA-48 carbapenemase-producing Enterobacteriaceae in Croatia. Retrospective screening for OXA-48 producers was performed on a collection of 296 nonrepetitive, carbapenem-nonsusceptible enterobacterial isolates collected from January 2011 to December 2012 from 40 participating centers in Croatia. Antimicrobial susceptibility profiles and production of carbapenemases were assessed phenotypically. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing were used for epidemiological analysis. Resistance genes were characterized by polymerase chain reaction (PCR) and sequencing. Plasmid localization of bla in isolates and transconjugants was investigated by S1-PFGE and Southern hybridization. PCR mapping was used for identification of genetic platform surrounding bla. Out of 296 carbapenem-nonsusceptible isolates, bla gene was detected in 12 Klebsiella pneumoniae isolates. All OXA-48-producing isolates showed varying resistance to carbapenems and 11 were multidrug resistant. All coproduced additional beta-lactamases, including CTX-M-15, which was detected in eight isolates. Isolates were delineated in five clonal types by PFGE corresponding to five sequence types (STs) assigned ST15, ST16, ST37, ST528, and ST1418. All OXA-48 isolates conjugated successfully and other resistance determinants were not cotransferred. bla was carried on a ∼60 kb IncL/M plasmid and was detected within Tn1999.2 composite transposon. OXA-48, a class D carbapenemase, is emerging as a potentially significant contributor among carbapenem-resistant Enterobacteriaceae in Croatia, alongside class A and B carbapenemases. Polyclonal genetic background of K. pneumoniae isolates carrying ∼60 kb incL/M plasmid indicates that dissemination of the bla gene is not driven exclusively by the spread of a single clone.

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Rotavirus is the major cause of severe diarrhea in young children worldwide. In countries like Croatia, where rotavirus vaccine has not been introduced in the national immunization program, prospective surveillance is necessary to establish the diversity of rotavirus strains. The aim of this study was to describe the prevalence and geographical distribution of rotavirus strains in Croatia and to detect the possible emergence of novel strains. Methods: The study was conducted among children 5 years of age with acute gastroenteritis at three hospitals located in different geographical regions of Croatia, during the years 2012 to 2014. Rotavirus was detected in stools using an immunochromatographic assay and then sent for further molecular analysis. Results: Genotyping of 822 rotaviruses showed that the predominant circulating strain was G1P[8] (61.9%), followed by G2P[4] (19.5%), G1P[4] (3.9%), and G3P [8] (2.9%). A high prevalence of reassortants among common human rotavirus genotypes was detected (7.7%). Possible zoonotic reassortants were found, including G8 and G6 strains. The latter is described for the first time in Croatia. Conclusions: This study represents pre-vaccination data that are important for decisions regarding immunization strategies in Croatia. The high prevalence of 'common' rotavirus strains circulating in Croatia may advocate for rotavirus vaccine introduction, but further surveillance is necessary to monitor the possible emergence of novel genotypes.

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