High virulence gene diversity in isolated in Central Italy.

Globally, poses a continuous burden on human health, causing both self-limiting and life-threatening diseases. Therefore, studying the profile of virulence genes and their combinations is essential to monitor the epidemiology and pathogenic potential of this important species. Thus, the aim of this study was to analyze related genetic features of clinical strains collected in Italy in 2012 in order to obtain a valid picture of their virulence profile that could be compared to similar studies made in other countries approximately in the same period.

Low biological cost of carbapenemase-encoding plasmids following transfer from Klebsiella pneumoniae to Escherichia coli.

Objectives: The objective of this study was to determine the biological cost, stability and sequence of two carbapenemase-encoding plasmids containing bla (pG12-KPC-2) and bla (pG06-VIM-1) isolated from Klebsiella pneumoniae when newly acquired by uropathogenic Escherichia coli clinical isolates of different genetic backgrounds.

Methods: The two plasmids were transferred into plasmid-free E. coli clinical isolates by transformation.

Transcriptome Remodeling Contributes to Epidemic Disease Caused by the Human Pathogen Streptococcus pyogenes.

Unlabelled: For over a century, a fundamental objective in infection biology research has been to understand the molecular processes contributing to the origin and perpetuation of epidemics. Divergent hypotheses have emerged concerning the extent to which environmental events or pathogen evolution dominates in these processes. Remarkably few studies bear on this important issue.

Correlation between genetic features of the mef(A)-msr(D) locus and erythromycin resistance in Streptococcus pyogenes.

We investigated the correlation between the genetic variation within mef(A)-msr(D) determinants of efflux-mediated erythromycin resistance in Streptococcus pyogenes and the level of erythromycin resistance. Twenty-eight mef(A)-positive strains were selected according to erythromycin MIC (4-32 μg/mL), and their mef(A)-msr(D) regions were sequenced. Strains were classified according to the bacteriophage carrying mef(A)-msr(D).

A study on erm(B)-mediated MLS resistance in Streptococcus pyogenes clinical isolates.

The constitutive or inducible macrolide-lincosamide-streptogramin (MLS) phenotype of 30 erm(B)-positive Streptococcus pyogenes isolates was determined by different methods and under various growth conditions and correlated to the sequence of the 5'-untranslated regions of erm(B). The MLS phenotype of one-third of the isolates could not be classified. In liquid medium, some of these isolates responded to induction only during the logarithmic phase of growth, while others expressed clindamycin resistance even under noninducing conditions.

Lysogenic transfer of mef(A) and tet(O) genes carried by Phim46.1 among group A streptococci.

We report the ex vivo lysogenic transfer of erythromycin and tetracycline resistance genes among group A streptococci (GAS). Of 42 susceptible strains, 69% acquired erythromycin/tetracycline resistance when infected with purified supernatants from strain m46 culture containing the phage Φm46.1.

Distribution of phage-associated virulence genes in pharyngeal group a streptococcal strains isolated in Italy.

The presence and assortment of 16 known virulence/resistance genetic determinants carried by prophages or prophage-like elements were tested in 212 clinical group A Streptococcus (GAS) strains and related to available data from SmaI macrorestriction/pulsed-field gel electrophoresis analysis and emm typing. A strong correlation existed among the three analyses. This finding supports the substantial contribution to the evolution and diversification of the GAS genome attributed to phages.