Department of Biology, Haverford College, Haverford, PA 19041, USA.
BMC Microbiol. 2011 Feb 27;11:44. doi: 10.1186/1471-2180-11-44.
Antimicrobial resistance is under-documented and commensal Escherichia coli can be used as indicator organisms to study the resistance in the community. We sought to determine the prevalence of resistance to broad-spectrum antimicrobials with particular focus on the quinolones, which have recently been introduced in parts of Africa, including Ghana.
Forty (13.7%) of 293 E. coli isolates evaluated were nalidixic acid-resistant. Thirteen (52%) of 2006 and 2007 isolates and 10 (66.7%) of 2008 isolates were also resistant to ciprofloxacin. All but one of the quinolone-resistant isolates were resistant to three or more other antimicrobial classes. Sequencing the quinolone-resistance determining regions of gyrA and parC, which encode quinolone targets, revealed that 28 quinolone-resistant E. coli harboured a substitution at position 83 of the gyrA gene product and 20 of these isolates had other gyrA and/or parC substitutions. Horizontally-acquired quinolone-resistance genes qnrB1, qnrB2, qnrS1 or qepA were detected in 12 of the isolates. In spite of considerable overall diversity among E. coli from Ghana, as evaluated by multilocus sequence typing, 15 quinolone-resistant E. coli belonged to sequence type complex 10. Five of these isolates carried qnrS1 alleles.
Quinolone-resistant E. coli are commonly present in the faecal flora of Accra residents. The isolates have evolved resistance through multiple mechanisms and belong to very few lineages, suggesting clonal expansion. Containment strategies to limit the spread of quinolone-resistant E. coli need to be deployed to conserve quinolone effectiveness and promote alternatives to their use.
抗菌药物耐药性的记录不足，而共生的大肠杆菌可作为指示菌，用于研究社区中的耐药性。我们旨在确定对广谱抗菌药物的耐药率，特别是在非洲部分地区（包括加纳）最近引入的喹诺酮类药物。
在评估的 293 株大肠杆菌分离株中，有 40 株（13.7%）对萘啶酸耐药。2006 年和 2007 年的 2006 株和 2008 年的 10 株（52%）分离株也对环丙沙星耐药。除了一个耐喹诺酮的分离株外，所有其他耐喹诺酮的分离株都对三种或更多其他抗菌药物类别耐药。对编码喹诺酮靶标的 gyrA 和 parC 的喹诺酮耐药决定区进行测序，结果显示 28 株喹诺酮耐药大肠杆菌的 gyrA 基因产物第 83 位有取代，其中 20 株分离株还有其他 gyrA 和/或 parC 取代。在 12 株分离株中检测到水平获得的喹诺酮耐药基因 qnrB1、qnrB2、qnrS1 或 qepA。尽管加纳大肠杆菌的总体多样性很大，如通过多位点序列分型评估的那样，但 15 株耐喹诺酮的大肠杆菌属于 10 型序列型复合物。其中 5 株分离株携带 qnrS1 等位基因。
在阿克拉居民的粪便菌群中，经常存在耐喹诺酮的大肠杆菌。这些分离株通过多种机制产生了耐药性，并且属于极少数的谱系，这表明存在克隆扩张。需要采取遏制策略来限制耐喹诺酮大肠杆菌的传播，以保护喹诺酮的有效性并促进替代药物的使用。
