RESUMO
AIMS: The aim of this study was to identify point mutations in the gyrA quinolone resistance determining region (QRDR) of Campylobacter coli (n = 27) and Campylobacter jejuni (n = 26) that confer nalidixic acid (NAL) resistance without conferring resistance to ciprofloxacin (CIP). METHODS AND RESULTS: Point mutations in the QRDR of gyrA from C. coli and C. jejuni isolates were identified by direct sequencing. All isolates (n = 14) with minimum inhibitory concentrations (MICs) >or=4 microg ml(-1) for CIP and >or=32 microg ml(-1) for NAL possessed a missense mutation leading to substitution of Ile for Thr at codon 86. Three isolates with a missense mutation leading to a Thr86Ala substitution had MICs <4 mug ml(-1) for CIP and >or=32 microg ml(-1) for NAL. CONCLUSIONS: These data confirm previous findings that Thr86Ile mutations confer resistance to both CIP and NAL. However, resistance to NAL alone was conferred by a single Thr86Ala mutation. SIGNIFICANCE AND IMPACT OF THE STUDY: Resistance to NAL alone arises independently from CIP resistance. In addition, the role of other previously described point mutations in quinolone resistance is discussed.
Assuntos
Anti-Infecciosos/farmacologia , Campylobacter/genética , Bovinos/microbiologia , Galinhas/microbiologia , Ciprofloxacina/farmacologia , DNA Girase/genética , Ácido Nalidíxico/farmacologia , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/genética , Campylobacter/efeitos dos fármacos , Campylobacter/isolamento & purificação , Campylobacter coli/efeitos dos fármacos , Campylobacter coli/genética , Campylobacter coli/isolamento & purificação , Campylobacter jejuni/efeitos dos fármacos , Campylobacter jejuni/genética , Campylobacter jejuni/isolamento & purificação , Farmacorresistência Bacteriana , Mutação de Sentido Incorreto/genética , Mutação Puntual/genéticaRESUMO
As part of a study identifying plasmids in Campylobacter, we isolated and sequenced two novel cryptic plasmids from an agricultural isolate of Campylobacter coli. The larger of the two plasmids, p3384, is 3316 bp in length and has a G+C content of 31.18%. A typical origin of replication consisting of five iterons was observed directly upstream of the first of three putative ORFs. The smaller plasmid, p3386, is 2426 bp in length and has a G+C content of 26.22%. Of the three putative ORFs detected on p3386, one shared homology with a putative protein from Campylobacter upsaliensis. The unique sequence of p3386 makes it attractive for further study concerning the evolutionary relationship of this plasmid to other Campylobacter plasmids, and to other Campylobacter isolates.
Assuntos
Campylobacter coli/genética , Campylobacter coli/isolamento & purificação , Clonagem Molecular , Vetores Genéticos/genética , Plasmídeos/genética , Composição de Bases , Sequência de Bases , Produtos Agrícolas , Replicação do DNA , Dados de Sequência Molecular , Fases de Leitura Aberta , Origem de Replicação , Homologia de Sequência do Ácido Nucleico , Transformação BacterianaRESUMO
We examined the fermentation of starch-based packing peanuts and agricultural wastes as a source of fermentable carbohydrates using Clostridium beijerinckii BA101. Using semidefined P2 medium containing packing peanuts and agricultural wastes, instead of glucose as a carbohydrate source, we measured characteristics of the fermentation including solvent production, productivity, and yield. With starch as substrate (control), the culture produced 24.7 g l(-1) acetone-butanol-ethanol (ABE), while with packing peanuts it produced 21.7 g l(-1) total ABE with a productivity of 0.20 g l(-1) h(-1) and a solvent (ABE) yield of 0.37. Cell growth in starch, packing peanuts, and agricultural wastes medium was different, possibly due to the different nature of these substrates. Using model agricultural waste, 20.3g l(-1) ABE was produced; when using actual waste, 14.8 g l(-1) ABE was produced. The use of inexpensive substrates will increase the economic viability of the conversion of biomass to butanol, and can provide new markets for these waste streams.
