Omulo Sylvia, Lofgren Eric T, Mugoh Maina, Alando Moshe, Obiya Joshua, Kipyegon Korir, Kikwai Gilbert, Gumbi Wilson, Kariuki Samuel, Call Douglas R
Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, USA; Community Health Analytics Initiative, Washington State University, Pullman, WA, USA.
Center for Global Health Research, Kenya Medical Research Institute, Nairobi, Kenya.
J Microbiol Methods. 2017 May;136:71-77. doi: 10.1016/j.mimet.2017.03.006. Epub 2017 Mar 18.
Investigators often rely on studies of Escherichia coli to characterize the burden of antibiotic resistance in a clinical or community setting. To determine if prevalence estimates for antibiotic resistance are sensitive to sample handling and interpretive criteria, we collected presumptive E. coli isolates (24 or 95 per stool sample) from a community in an urban informal settlement in Kenya. Isolates were tested for susceptibility to nine antibiotics using agar breakpoint assays and results were analyzed using generalized linear mixed models. We observed a <3-fold difference between prevalence estimates based on freshly isolated bacteria when compared to isolates collected from unprocessed fecal samples or fecal slurries that had been stored at 4°C for up to 7days. No time-dependence was evident (P>0.1). Prevalence estimates did not differ for five distinct E. coli colony morphologies on MacConkey agar plates (P>0.2). Successive re-plating of samples for up to five consecutive days had little to no impact on prevalence estimates. Finally, culturing E. coli under different conditions (with 5% CO or micro-aerobic) did not affect estimates of prevalence. For the conditions tested in these experiments, minor modifications in sample processing protocols are unlikely to bias estimates of the prevalence of antibiotic-resistance for fecal E. coli.
研究人员常常依靠对大肠杆菌的研究来确定临床或社区环境中抗生素耐药性的负担情况。为了确定抗生素耐药性的流行率估计值是否对样本处理和解释标准敏感，我们从肯尼亚一个城市非正式定居点的社区收集了推测性大肠杆菌分离株（每个粪便样本24株或95株）。使用琼脂断点试验检测分离株对九种抗生素的敏感性，并使用广义线性混合模型分析结果。与从未经处理的粪便样本或在4°C下储存长达7天的粪便悬液中收集的分离株相比，我们观察到基于新鲜分离细菌的流行率估计值之间的差异小于3倍。未发现明显的时间依赖性（P>0.1）。在麦康凯琼脂平板上，五种不同的大肠杆菌菌落形态的流行率估计值没有差异（P>0.2）。样本连续重新接种多达五天对流行率估计值几乎没有影响。最后，在不同条件下（5%二氧化碳或微需氧）培养大肠杆菌并不影响流行率估计值。对于这些实验中测试的条件，样本处理方案的微小修改不太可能使粪便大肠杆菌抗生素耐药性流行率的估计产生偏差。
