Srichamnong Warangkana, Kalambaheti Natcha, Woskie Susan, Kongtip Pornpimol, Sirivarasai Jintana, Matthews Karl R
Institute of Nutrition Mahidol University Phutthamonthon, Nakhon Pathom Thailand.
Department of Public Health Zuckerberg College of Health Sciences University of Massachusetts Lowell Lowell MA USA.
Food Sci Nutr. 2021 Jan 23;9(3):1460-1470. doi: 10.1002/fsn3.2116. eCollection 2021 Mar.
Antibiotics used during production of food crops to control plant diseases may result in selection of antibiotic-resistant bacteria and occurrence of antibiotic residues. The aim of this research was to evaluate the effect of antibiotics used in butterhead lettuce production on persistence of commensal microbiota. Butterhead lettuce were treated with antibiotics (oxytetracycline, gentamicin, and streptomycin) at different concentrations (100, 200, 300, 400 and 500 ppm) starting at 5 weeks' growth by spraying once daily for 4 weeks and harvesting 7 days after the final spray application. The population of total aerobic bacteria and antibiotic-resistant bacteria were determined. The results showed antibiotic usage significantly decreased bacterial populations on lettuce. Moreover, increased concentration of antibiotics resulted in significantly greater decrease in bacterial populations. At a concentration of 500 ppm, all antibiotics achieved an approximate 2 log CFU/g decrease in bacterial populations. A stable population (4 log CFU/g) of potentially antibiotic-resistant commensal microbiota were maintained throughout production. Screening for level of susceptibility indicated that bacteria exhibited greater resistance to oxytetracycline than gentamicin. In conclusion, application of antibiotics failed to eliminate commensal microbiota, demonstrating large populations of antibiotic-resistant bacteria reside on lettuce grown under conditions used in the present study. This is the first study focused on antibiotic usage on hydroponic systems. Results of this study suggest regulations directed at antibiotic use on food crops must be developed and implemented to control the selection and spread of antibiotic-resistant bacteria that present a global health concern.
在粮食作物生产过程中用于控制植物病害的抗生素可能会导致抗生素抗性细菌的产生以及抗生素残留的出现。本研究的目的是评估在奶油生菜生产中使用抗生素对共生微生物群持久性的影响。从生长5周开始，对奶油生菜用不同浓度（100、200、300、400和500 ppm）的抗生素（土霉素、庆大霉素和链霉素）进行处理，每天喷雾一次，持续4周，并在最后一次喷雾后7天进行收获。测定了总需氧菌和抗生素抗性细菌的数量。结果表明，使用抗生素显著降低了生菜上的细菌数量。此外，抗生素浓度的增加导致细菌数量的下降幅度显著增大。在500 ppm的浓度下，所有抗生素使细菌数量减少了约2个对数CFU/g。在整个生产过程中，潜在的抗生素抗性共生微生物群数量保持稳定（4个对数CFU/g）。药敏水平筛选表明，细菌对土霉素的抗性比对庆大霉素的抗性更强。总之，抗生素的应用未能消除共生微生物群，表明在本研究使用的条件下种植的生菜上存在大量抗生素抗性细菌。这是第一项关注水培系统中抗生素使用情况的研究。本研究结果表明，必须制定并实施针对粮食作物抗生素使用的法规，以控制对抗生素抗性细菌的选择和传播，这些细菌是全球健康关注的问题。
