1,721,017 research outputs found
Tn6249, a new Tn6162 transposon derivative carrying a double-integron platform involved with acquisition of the blaVIM-1 metallo-β-lactamase gene in Pseudomonas aeruginosa
No full textTn6249, a new Tn6162 transposon derivative carrying a double-integron platform involved with acquisition of the blaVIM-1 metallo-β-lactamase gene in Pseudomonas aeruginosa.
No full textEpidemiology and clinical relevance of microbial resistance determinants versus anti-Gram-positive agents
No full textGram-positive pathogens are a major cause of community-acquired and hospital-acquired infections, and exhibit a remarkable ability to develop antibiotic resistance. Methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide-resistant enterococci (GRE) and multidrug-resistant pneumococci are currently the major resistance challenges among Gram-positives, due to their global dissemination and overall clinical impact. The mechanisms of evolution of these resistance phenotypes are based on a diverse array of mutational events and gene transfer phenomena carried out by several types of mobile genetic elements, followed by the dissemination of successful resistant clones. Resistance to glycopeptides in staphylococci remains uncommon, likely due to fitness issues. Resistance to the new anti-Gram-positive agents (linezolid, daptomycin and tigecycline) overall remains very rare. However, a transferable resistance mechanism to linezolid, mediated by ribosomal target modification by the Cfr protein, has recently emerged among S. aureus, being a matter of raising concern. Linezolid resistance among enterococci and coagulase-negative staphylococci is also increasingly reported. Moreover, a role for antibiotic resistance has been advocated in the recent increase of Clostridium difficile infection (CDI) associated with the emergence of hypervirulent strains
Resistance determinants and clonal diversity in group A streptococci collected during a period of increasing macrolide resistance.
No full textSusceptibility to macrolides and lincosamides was investigated with 299 consecutive nonduplicate Streptococcus pyogenes clinical isolates collected over a 6-year period (1992 to 1997) from an area of central Italy. During this period, macrolide resistance rates steadily increased (from 9% in 1992 to 53% in 1997; P < 0.001). The increase was caused by isolates with a macrolide-lincosamide-streptogramin B resistance phenotype, carrying mostly erm(B) but also erm(TR) genes, that were not detected in the first 2 years and were detected with increasing prevalence (8, 5, 26, and 37%, respectively) during the following 4 years. During the same period, the prevalence of isolates with a macrolide resistance phenotype, carrying mef(A) determinants, did not vary significantly; on average it was 13%, with modest rate fluctuations in different years and no definite trend. Molecular typing revealed a remarkable clonal diversity among susceptible and resistant isolates and a notable heterogeneity of the genetic environment of the resistance genes. The analysis of clonal diversity in relation with resistance phenotypes and genotypes revealed that increased macrolide resistance rates were due to a complex interplay of different mechanisms, with a relevant contribution played by an "epidemic" spread of genetic elements carrying the erm(B) gene among the circulating streptococcal population
Resistenza ai macrolidi e clonalità di ceppi Streptococcus pyogenes isolati da una popolazione della Provincia di Siena
No full text[Carbapenem resistance in Pseudomonas aeruginosa isolates: an example of interaction between different mechanisms].
No full textUpdate on the antibiotic resistance crisis.
No full textAntibiotics tend to lose their efficacy over time due to the
emergence and dissemination of resistance among bacterial
pathogens. Strains with resistance to multiple antibiotic classes
have emerged among major Gram-positive and Gram-negative
species including Staphylococcus aureus, Enterococcus spp.,
Pseudomonas aeruginosa, Acinetobacter spp.
Enterobacteriaceae, and Neisseria gonorrhoeae. With some
Gram-negatives, resistance may involve most or even all the
available antimicrobial options, resulting in extremely drugresistant
or totally drug-resistant phenotypes. This so-called
‘antibiotic resistance crisis’ has been compounded by the
lagging in antibiotic discovery and development programs
occurred in recent years, and is jeopardizing the essential role
played by antibiotics in current medical practices
Molecular typing of Staphylococcus aureus isolates from an intensive care unit.
No full textSeventeen S. aureus clinical isolates, collected from an Intensive Care Unit (ICU) during a seven-month period were analyzed to investigate their antimicrobial susceptibility and clonal diversity. Eleven isolates (65%) were found to be resistant to methicillin (MRSA). Pulsed-field gel electrophoresis (PFGE) profiles of genomic DNAs, and analysis of the polymorphisms of the variable regions of the protein A (spa) and coagulase (coa) genes revealed a lower clonal heterogeneity among MRSA than among methicillin-susceptible isolates (MSSA). Two of the MRSA clones were repeatedly isolated in different patients, within a variable period of time, suggesting the presence in the ward of a resident, endemic and multi-drug resistant MRSA population. Our results also emphasize the lower discriminatory power of spa and coa typing compared with PFGE typing
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