strain with no parC mutations. This is consistent with previous findings that gyrA mutations are necessary for quinolone resistance, whereas parC mutations appear to be complementary, as resistant strains do not carry parC mutations alone. – 6 Some studies further suggest that additional parC mutations facilitate increasing levels of resistance, but our study did not support this. For example, ...

Fluoroquinolone treatment failure has been reported in patients with nalidixic acid-resistant Salmonella infections. Both chromosomal- and plasmid-mediated quinolone-resistance mechanisms have been described. The objective of this study was to identify the prevalence of these mechanisms in a collection of 41 Salmonella spp. clinical isolates causing acute gastroenteritis, obtained in the Hospit...

OBJECTIVES Enteroaggregative Escherichia coli (EAEC) and enterotoxigenic E. coli (ETEC) are among the most frequent microorganisms causing traveller's diarrhoea. The aim of this study was to investigate the evolution of antimicrobial resistance in EAEC and ETEC causing diarrhoea in patients who had travelled to different developing countries, comparing two periods of time, 1994-97 and 2001-04. ...

Klebsiella pneumoniae causes common and severe hospital- and community-acquired infections with a high incidence of multidrug resistance. The emergence and spread of beta-lactamase-producing K. pneumoniae strains highlight the need to develop new therapeutic strategies. In this study, we developed antisense peptide nucleic acids (PNAs) conjugated to the (KFF)(3)K peptide and investigated whethe...

Fourteen strains of S. Typhi (n=13) and S. Paratyphi A (n=1) resistant to ciprofloxacin were compared with 30 ciprofloxacin decreased-susceptibility strains on the basis of qnr plasmid analysis, and nucleotide substitutions at gyrA, gyrB, parC and parE. In ciprofloxacin-resistant strains, five S. Typhi and a single S. Paratyphi A showed triple mutations in gyrA (Ser83-->Phe, Asp87-->Asn, Glu133...

Twelve isolates of Salmonella typhi isolated in Vellore, India had reduced susceptibility to 4-quinolones (MIC of ciprofloxacin 0.256 mg/L). One isolate was isolated in 1992 but the remaining 11 were isolated in 1994. The section of the gyrA gene from codons 24 to 185, which includes the "Quinolone Resistance Determining Region", was amplified by the polymerase chain reaction and, after separat...

Species-specific bacterial identification of clinical specimens is often limited to a few species due to the difficulty of performing multiplex reactions. In addition, discrimination of amplicons is time-consuming and laborious, consisting of gel electrophoresis, probe hybridization, or sequencing technology. In order to simplify the process of bacterial identification, we combined anchored in ...

When the lethal action of a C-8 methoxyl fluoroquinolone against clinical isolates of Mycobacterium tuberculosis in liquid medium was measured, the compound was found to be three to four times more effective (as determined by measuring the 90% lethal dose) than a C-8-H control fluoroquinolone or ciprofloxacin against cells having a wild-type gyrA (gyrase) gene. Against ciprofloxacin-resistant s...

Campylobacter jejuni, a major foodborne human pathogen, has become increasingly resistant to fluoroquinolone (FQ) antimicrobials. By using clonally related isolates and genetically defined mutants, we determined the fitness of FQ-resistant Campylobacter in chicken (a natural host and a major reservoir for C. jejuni) in the absence of antibiotic selection pressure. When monoinoculated into the h...