ABSTRACT
@#This study analysed the mechanisms of quinolone resistance among enterotoxigenic Escherichia coli (ETEC) in a periurban area of Lima, Peru. The susceptibility to nalidixic acid and ciprofloxacin, the role of Phe-Arg-b-Naphtylamyde inhibitable-(PAbN) efflux pumps, the presence of mutations in gyrA and parC as well as the presence of aac(6’)Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD, qnrVC and oqxAB were determined in 31 ETEC from previous case/control studies of children’s diarrhoea. Discordances between disk diffusion, with all isolates showing intermediate or fully resistance to nalidixic acid, and minimal inhibitory concentration (MIC), with 7 isolates being below considered resistance breakpoint, were observed. Twenty-one isolates possessed gyrA mutations (19 S83L, 2 S83A). AAC(6’) Ib-cr, QnrS, QnrB and QepA were found in 7, 6, 2 and 1 isolates respectively, with 3 isolates presenting 2 transferable mechanisms of quinolone resistance (TMQR) concomitantly. TMQR were more frequent among isolates with MIC to nalidixic acid ranging from 2 to 16 mg/L (p=0.03), while gyrA mutations were more frequent among isolates with nalidixic acid MIC > 128 mg/L (p=0.0002). In summary, the mechanisms of quinolone resistance present in ETEC isolates in Peru have been described. Differences in the prevalence of underlying mechanisms associated with final MIC levels were observed. The results suggest two different evolutive strategies to survive in the presence of quinolones related to specific bacterial genetic background.
ABSTRACT
Objective To investigate the infection and distribution situations of diarrheogenic Escherichia coli among food practi‐tioners in Changsha City and to understand the carrying status of its virulence genes .Methods Totally 258 food practitioners from 9 units of Changsha City were extracted as the research subjects .Diarrheogenic Escherichia coli was detected by adopting the real time fluorescence multiple PCR .Results The infection rate of diarrheogenic Escherichia coli was 15 .5% (40/258) ,in which EAEC accounted for 10 .9% (28/258) ,EPEC for 3 .1% (8/258) and EHEC for 1 .6% (4/258) respectively ,EIEC and ETEC were not found .Among 28 strains of EAEC ,26 strains carried uidA gene ,13 strains carried aggR+pic gene and 27 strains carried astA gene , the carrying rates were 92 .9% ,46 .4% and 96 .4% respectively ;eight strains of EPEC all carried eae and uidA genes ;among 4 strains of EHEC ,3 strains carried eae gene ,moreover all 4 strains carried stx1+ stx2 gene .Conclusion Establishing a mechanism for continuously monitoring diarrheogenic Escherichia coli and deeply studying its molecular epidemiologic theory not only provide the essential data for the supervisory departments formulating and evaluating the public health measures ,but also has an important significance for evaluating the food safety status ,which can effectively control infectious source and protect the people′s health .