Fecal bacteria in flies.

Synanthropic filth flies are common where sanitation is poor and fecal wastes are accessible to them. These flies have been proposed as mechanical vectors for the localized transport of fecal microbes including antimicrobial resistant (AMR) organisms and associated antimicrobial resistance genes (ARGs), increasing exposure risks. We evaluated whether an onsite sanitation intervention in Maputo, Mozambique reduced the concentration of enteric bacteria and the frequency of detection of ARGs carried by flies collected in household compounds of low-income neighborhoods. Additionally, we assessed the phenotypic resistance profile of Enterobacteriaceae isolates recovered from flies during the pre-intervention phase. After fly enumeration at study compounds, quantitative polymerase chain reaction was used to quantify an enteric 16S rRNA gene (i.e., specific to a cluster of phylotypes corresponding to 5% of the human fecal microflora), 28 ARGs, and Kirby Bauer Disk Diffusion of Enterobacteriaceae isolates was utilized to assess resistance to eleven clinically relevant antibiotics. The intervention was associated with a 1.5 log10 reduction (95% confidence interval: -0.73, -2.3) in the concentration of the enteric 16S gene and a 31% reduction (adjusted prevalence ratio = 0.69, [0.52, 0.92]) in the mean number of ARGs per fly compared to a control group with poor sanitation. This protective effect was consistent across the six ARG classes that we detected. Enterobacteriaceae isolates–only from the pre-intervention phase–were resistant to a mean of 3.4 antibiotics out of the eleven assessed. Improving onsite sanitation infrastructure in low-income informal settlements may help reduce fly-mediated transmission of enteric bacteria and the ARGs carried by them.

与人伴生的腐食蝇类（synanthropic filth flies）常出没于卫生条件恶劣、粪便可被其接触的环境。这类蝇类被认为是粪便微生物（包括耐药（antimicrobial resistant, AMR）病原体及相关耐药基因（antimicrobial resistance genes, ARGs））局部传播的机械媒介，提升了人类暴露风险。本研究评估了莫桑比克马普托市的现场卫生干预措施，是否能降低低收入社区住宅院落中采集的蝇类携带的肠道细菌浓度与耐药基因检出频率。此外，本研究还对干预前阶段从蝇类中分离得到的肠杆菌科（Enterobacteriaceae）菌株的表型耐药谱进行了分析。在对研究院落的蝇类进行计数后，本研究采用定量聚合酶链式反应（quantitative polymerase chain reaction, qPCR）对1种肠道16S rRNA基因（即对应占人类粪便菌群5%的类群簇的特异性基因）、28种耐药基因进行定量；同时利用肠杆菌科菌株的柯比-鲍尔纸片扩散法（Kirby Bauer Disk Diffusion）评估其对11种临床相关抗生素的耐药性。与卫生条件较差的对照组相比，干预组的肠道16S rRNA基因浓度降低了1.5个log₁₀单位（95%置信区间：-0.73, -2.3），单只蝇类携带的耐药基因平均数量降低了31%（校正患病率比=0.69, [0.52, 0.92]）。该保护效应在本研究检出的6类耐药基因中均一致存在。仅干预前阶段分离得到的肠杆菌科菌株，在11种受试抗生素中平均对3.4种产生耐药性。改善低收入非正式定居点的现场卫生基础设施，或有助于降低蝇类介导的肠道细菌及其携带耐药基因的传播风险。