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Abstract: Background: Monitoring the emergence of drug-resistant influenza variants is crucial in influenza surveillance programs. Objectives: Influenza A kinetics and the emergence of drug-resistant strains in hospitalized patients treated with oseltamivir were investigated. Study design: Sequential samples from oseltamivir-treated and -untreated hospitalized patients in the period November 2011 through April 2012 were analyzed. NA gene was sequenced in samples from oseltamivir treated patients. Clonal analysis of the viral population was performed in patients unresponsive to treatment. Viral kinetics was determined in 24 (14 immunocompromised and 10 immunocompetent) A(H3N2)-positive patients treated and 24 (10 immunocompromised and 14 immunocompetent) untreated patients. Results: Viral shedding was significantly reduced in treated vs untreated immunocompromised patients (7 vs 22 days, p <0.05, respectively). Viral load decreased significantly in immunocompromised and immunocompetent treated patients as compared with immunocompromised and immunocompetent untreated patients (0.73 and 0.93 vs 0.47 and 0.45log10/day, p <0.05). In two (8.3%) treated patients with prolonged virus shedding, the oseltamivir resistance R292K mutation was revealed. In these patients, clonal analysis of the virus population showed the presence of additional oseltamivir-resistant mutants (E119V, N294S and deletion Del247–250). Conclusions: Oseltamivir resistance is reported for the first time in A(H3N2) virus strains during the 2011–2012 influenza season. Different drug-resistant viruses emerged in hospitalized immunocompromised patients showing prolonged virus shedding. [Copyright &y& Elsevier]

Background: Influenza A viruses are characterised by their rapid evolution, and the appearance of point mutations in the viral hemagglutinin (HA) domain causes seasonal epidemics. The A(H3N2) virus has higher mutation rate than the A(H1N1) virus. The aim of this study was to reconstruct the evolutionary dynamics of the A(H3N2) viruses circulating in Italy between 2004 and 2012 in the light of the forces driving viral evolution., Methods: Phylodinamic analyses were made using a Bayesian method, and codon-specific positive selection acting on the HA coding sequence was evaluated., Results: Global and local phylogenetic analyses showed that the Italian strains collected between 2004 and 2012 grouped into five significant Italian clades that included viral sequences circulating in different epidemic seasons. The time of the most recent common ancestor (tMRCA) of the tree root was between May and December 2003. The tMRCA estimates of the major clades suggest that the origin of a new viral strain precedes the effective circulation of the strain in the Italian population by 6-31 months, thus supporting a central role of global migration in seeding the epidemics in Italy. The study of selection pressure showed that four codons were under positive selection, three of which were located in antigenic sites. Analysis of population dynamics showed the alternation of periods of exponential growth followed by a decrease in the effective number of infections corresponding to epidemic and inter-epidemic seasons., Conclusions: Our analyses suggest that a complex interaction between the immune status of the population, migrations, and a few selective sweeps drive the influenza A(H3N2) virus evolution. Our findings suggest the possibility of the year-round survival of local strains even in temperate zones, a hypothesis that warrants further investigation.

Enterovirus 68 (EV-D68) was associated with mild to severe respiratory infections. In the last 4 years, circulation of different EV-D68 strains has been documented worldwide. In this study, the phylogenetic characterization of nine EV-D68 strains identified in patients in the 2010-2012 period and 12 additional EV-D68 Italian strains previously identified in 2008 in Italy was described. From January 2010 to December 2012, a total of 889 respiratory specimens from 588 patients stayed or visited at the Fondazione IRCCS Policlinico San Matteo were positive for HRV or HEV. Extracted nucleic acids were amplified by one-step RT-PCR with primer specific for VP1 region of EV-D68 and purified positive PCR products were directly sequenced. Overall, 9/3736 (0.24%) patients were EV-D68 positive. Of these, 7/9 (77.8%) were pediatric and two (22.2%) were adults. Five out of seven (71.4%) pediatric patients had lower respiratory tract infection with oxygen saturation <94%. Four cases were detected from August through October 2010, while five other cases from September through December 2012. The Italian EV-D68 strains in 2008 belonged to clade A (n = 5) and clade C (n = 7). In 2010 all the Italian strains belonged to clade A (n = 4) and in 2012, four Italian strains belonged to clade B and one to clade A. In conclusion, we provide additional evidence supporting a role of EV-D68 in severe respiratory infection in pediatric patients. In addition, all the three EV-D68 clades circulating worldwide were identified in Italy in a 5-year period of time., (© 2013 Wiley Periodicals, Inc.)