Characterization of poxtA, a novel phenicol-oxazolidinone-tetracycline resistance gene from an MRSA of clinical origin.

Objectives: To characterize a novel phenicol-oxazolidinone-tetracycline resistance gene, named poxtA, identified in a previously described MRSA strain that was highly resistant to linezolid and also carried the cfr gene.

Methods: The poxtA gene was identified by bioinformatic analysis of the whole genome sequence of Staphylococcus aureus AOUC-0915. The poxtA gene was cloned in a shuttle plasmid vector and expressed in Escherichia coli, S.

ICESp2905, the erm(TR)-tet(O) element of Streptococcus pyogenes, is formed by two independent integrative and conjugative elements.

In ICESp2905, a widespread erm(TR)- and tet(O)-carrying genetic element of Streptococcus pyogenes, the two resistance determinants are contained in separate fragments inserted into a scaffold of clostridial origin. ICESp2905 (∼65.6 kb) was transferable not only in its regular form but also in a defective form lacking the erm(TR) fragment (ICESp2906, ∼53.

PCR real time assays for the early detection of BKV-DNA in immunocompromised patients.

Testing for viral BKV-DNA in urine is a non-invasive early detection and monitoring tool in the diagnostic of BKV-related pathologies: quantitative analysis by Real-Time PCR can provide useful information in addition to cytologic analysis, although our study suggests that high BKV viruria is not necessarily associated with kidney or bladder damage.

Synergistic potential of ceftazidime plus amikacin or levofloxacin against Pseudomonas aeruginosa as determined using a checkerboard and a disk diffusion technique.

The synergistic potential of ceftazidime plus amikacin or levofloxacin was assessed against 61 Pseudomonas aeruginosa isolates with variable susceptibility patterns to the 3 antibiotics. A checkerboard broth method and a disk diffusion method were used and compared. The latter, also easy to perform as a triple-disk assay, could be a helpful laboratory screening tool for drug synergism to drive possible combination treatments.

Molecular characterization of clinical Streptococcus pneumoniae isolates with reduced susceptibility to fluoroquinolones emerging in Italy.

Fifteen Streptococcus pneumoniae clinical isolates with reduced fluoroquinolone susceptibility (defined as a ciprofloxacin MIC of > or = 4 microg/ml), all collected in Italy in 2000-2003, were typed and subjected to extensive molecular characterization to define the contribution of drug target alterations and efflux mechanisms to their resistance. Serotyping and pulsed-field gel electrophoresis analysis indicated substantial genetic unrelatedness among the 15 isolates, suggesting that the new resistance traits arise in multiple indigenous strains rather than through clonal dissemination. Sequencing of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE demonstrated that point mutations producing single amino acid changes were more frequent in topoisomerase IV (parC mutations in 14 isolates and parE mutations in 13) than in DNA gyrase subunits (gyrA mutations in 7 isolates and no gyrB mutations observed).

Presence of a vanA-carrying pheromone response plasmid (pBRG1) in a clinical isolate of Enterococcus faecium.

Sex pheromone plasmids, frequently found in Enterococcus faecalis, have rarely been detected in Enterococcus faecium. pBRG1 is an approximately 50-kb vanA-carrying conjugative plasmid of an E. faecium clinical isolate (LS10) that is transferable to E.

Phenotypes and genotypes of erythromycin-resistant pneumococci in Italy.

Of 120 erythromycin-resistant pneumococci isolated in Italian hospitals, 39 (32.5%) were M-type isolates, carrying the mef gene alone. The mef gene was also detected, together with erm(AM), in one constitutively resistant isolate and in five isolates of the partially inducible phenotype.

A novel efflux system in inducibly erythromycin-resistant strains of Streptococcus pyogenes.

Streptococcus pyogenes strains inducibly resistant (iMLS phenotype) to macrolide, lincosamide, and streptogramin B (MLS) antibiotics can be subdivided into three phenotypes: iMLS-A, iMLS-B, and iMLS-C. This study focused on inducibly erythromycin-resistant S. pyogenes strains of the iMLS-B and iMLS-C types, which are very similar and virtually indistinguishable in a number of phenotypic and genotypic features but differ clearly in their degree of resistance to MLS antibiotics (high in the iMLS-B type and low in the iMLS-C type).