Introduction: Typhoidal Salmonella causes an invasive infection resulting in 200 000 deaths among 20 million patients annually. Typhoid remains a public health problem in Southeast Asia, the Indian subcontinent, Africa, and South America. Traveler’s diarrhea caused by Salmonella is common in Asia. Outbreaks of typhoidal Salmonella resistant to ampicillin, chloramphenicol, and t...

PURPOSE To assess the in vitro susceptibility of Streptococcus pneumoniae, Staphylococcus aureus and coagulase-negative staphylococci (CoNS) ocular isolates to antibiotics, and identify changing trends in resistance over a 10-year period. METHODS All isolates from ocular infections collected between 2000 and 2009 were prospectively tested against several antibiotics in vitro. S. pneumoniae is...

quinolones are a large and widely consumed class of synthetic drugs. expanded-spectrum quinolones, like ciprofloxacin are highly effective against gram-negative bacteria, especially escherichia coli. in e. coli the major target for quinolones is dna gyrase. this enzyme is composed of two subunits, gyra and gyrb encoding by gyra and gyrb, respectively. mutations in either of these genes cause qu...

BACKGROUND Recent analysis of Stenotrophomonas maltophilia has identified a novel family of resistance genes (Smqnr) encoding pentapeptide repeat proteins, which confer low-level resistance to quinolones. This study describes further novel variants present in clinical isolates of S. maltophilia and investigates their effect on resistance to a number of quinolones in an Escherichia coli host. ...

Quinolone resistance is caused mainly by chromosomal mutations in gram negative bacteria. In 1998, plasmid-mediated resistance to quinolones in clinical isolates was first reported in a Klebsiella pneumoniae strain. Locus qnr (quinolone resistance) was responsible of the quinolone resistance in this plasmid. qnr codes a protein whose function is protect both DNA-girase and topoisomerase IV from...

Although quinolones have been in clinical use for decades, the mechanism underlying drug activity and resistance has remained elusive. However, recent studies indicate that clinically relevant quinolones interact with Bacillus anthracis (Gram-positive) topoisomerase IV through a critical water-metal ion bridge and that the most common quinolone resistance mutations decrease drug activity by dis...

Antibiotic resistance poses a major threat to human health. It is therefore important to characterize the frequency of resistance within natural bacterial environments. Many studies have focused on characterizing the frequencies with which horizontally acquired resistance genes segregate within natural bacterial populations. Yet, very little is currently understood regarding the frequency of se...

background and aims: extended-spectrum β-lactamase (esbl) producing gram negative bacteria are resistant to penicillins, narrow and extended-spectrum cephalosporins, and aztreonam; also they are frequently resistant to trimethoprim-sulfamethoxazole, aminoglycosides, and quinolones. this study aimed to investigate the prevalence of plasmid-mediated quinolone resistance (pmqr) determinants qnra, ...