INTRODUCTION Listeria species are susceptible to most antibiotics. However, over the last decade, increasing reports of multidrug-resistant Listeria spp. from various sources have prompted public health concerns. The objective of this study was to characterize the antibiotic susceptibility of Listeria spp. and the genetic mechanisms that confer resistance. METHODOLOGY Forty-six Listeria spp. ...

OBJECTIVE Phenotypic and genotypic characterization of the antimicrobial resistance of German Escherichia coli strains isolated during 1999-2001 from cattle, swine and poultry. MATERIALS AND METHODS Three hundred and seventeen isolates were tested for their resistance to 17 antimicrobial agents by broth microdilution. Resistant strains were screened by molecular methods for resistance genes, ...

The ability of sequential subcultures in subinhibitory concentrations of gemifloxacin, trovafloxacin, ciprofloxacin, gatifloxacin and moxifloxacin to select resistant mutants was studied in 16 pneumococci [eight with ciprofloxacin MICs (mg/L) 0.25-1; four with 8-16; four with 16-32]. Subculturing was done 50 times, or until mutants with elevated MICs (> or = 4 x) to the selecting drug emerged. ...

Mutations associated with fluoroquinolone resistance in clinical isolates of Proteus mirabilis were determined by genetic analysis of the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE. This study included the P. mirabilis type strain ATCC 29906 and 29 clinical isolates with reduced susceptibility (MIC, 0.5 to 2 microg/ml) or resistance (MIC, > or =4 microg/ml) to ...

Cholera has reinstated its deadly grip on the planet with recent epidemics in Zimbabwe and Haiti (1, 2), along with the emergence of Vibrio cholerae having reduced susceptibility to fluoroquinolones. India also experiences frequent outbreaks caused by multidrug-resistant V. cholerae (3). We report reduced sensitivity to ciprofloxacin in V. cholerae O1 El Tor Ogawa and novel multiple mutations i...

OBJECTIVES Quinolone resistance in the opportunistic pathogen Pseudomonas aeruginosa is commonly caused by mutations that alter the target molecules DNA gyrase/topoisomerase IV, or cause activation of various efflux systems. We have analysed the effect of quinolone resistance caused by DNA gyrase/topoisomerase IV mutations on bacterial fitness. METHODS Norfloxacin-resistant mutants were isola...

We report two cases of infection with clonally unrelated, high-level ciprofloxacin-resistant, b-lactamase-producing strains of Salmonella enterica Typhimurium. Resistance was caused by four topoisomerase mutations, in GyrA, GyrB, and ParC and increased drug efflux. Ciprofloxacin treatment failed in one case. In the second case, reduced susceptibility to third-generation cephalosporins occurred ...

In Hong Kong, ParC changes among high-level quinolone-resistant Neisseria gonorrhoeae (QRNG) isolates at Ser-87-->Arg were associated with a higher level of resistance than a Ser-87-->Ile alteration. Two previously undescribed mutations in clinical isolates occurring in gyrA, conferring Ala-92-->Pro and Asp-95-->Tyr changes, were detected. Nine different outer membrane lipoprotein (Lip) repeat ...