Amoxicillin therapy of poultry flocks: effect upon the selection of amoxicillin-resistant commensal Campylobacter spp.

Background: The aim of this study was to investigate the effect of amoxicillin therapy of poultry flocks upon the persistence of commensal Campylobacter spp. and the incidence of antibiotic resistance.

Methods: Four poultry flocks naturally colonized with Campylobacter were treated with amoxicillin and monitored before, during and up to 4 weeks post-treatment.

Involvement of the putative ATP-dependent efflux proteins PatA and PatB in fluoroquinolone resistance of a multidrug-resistant mutant of Streptococcus pneumoniae.

The multidrug-resistant mutant Streptococcus pneumoniae M22 constitutively overexpresses two genes (patA and patB) that encode proteins homologous to known efflux proteins belonging to the ABC transporter family. It is shown here that PatA and PatB were strongly induced by quinolone antibiotics and distamycin in fluoroquinolone-sensitive strains. PatA was very important for growth of S.

Incidence and mechanism of ciprofloxacin resistance in Campylobacter spp. isolated from commercial poultry flocks in the United Kingdom before, during, and after fluoroquinolone treatment.

Five commercial broiler flocks were treated with a fluoroquinolone for a clinically relevant infection. Fresh feces from individual chickens and environmental samples were cultured for campylobacters before, during, and weekly posttreatment until slaughter. Both Campylobacter jejuni and C.

Expression of efflux pump gene pmrA in fluoroquinolone-resistant and -susceptible clinical isolates of Streptococcus pneumoniae.

Thirty-four ciprofloxacin-resistant (MIC > or = 2 microg/ml) and 12 ciprofloxacin-susceptible clinical isolates of Streptococcus pneumoniae were divided into four groups based upon susceptibility to norfloxacin and the effect of reserpine (20 microg/ml). The quinolone-resistance-determining regions of parC, parE, gyrA, and gyrB of all ciprofloxacin-resistant clinical isolates were sequenced, and the activities of eight other fluoroquinolones, acriflavine, ethidium bromide, chloramphenicol, and tetracycline in the presence and absence of reserpine were determined. Despite a marked effect of reserpine upon the activity of norfloxacin, there were only a few isolates for which the activity of another fluoroquinolone was enhanced by reserpine.