Researchers at the University of California, Davis have published a study that shows unpasteurized cow milk can harbor a large quantity of antimicrobial-resistant genes if left at room temperature. The study demonstrated bacteria that held antimicrobial-resistant genes transferred them to other bacteria species, potentially spreading resistance if consumed.
"We don't want to scare people, we want to educate them. If you want to keep drinking raw milk, keep it in your refrigerator to minimize the risk of it developing bacteria with antibiotic-resistant genes," said lead author Jinxin Liu, a postdoctoral researcher in the Department of Food Science and Technology at UC Davis.
In addition to potentially spreading resistance, raw milk was seen to lack the abundant supply of probiotics compared to pasteurized milk samples according to the study.
"Two things surprised us," said Liu. "We didn't find large quantities of beneficial bacteria in the raw milk samples, and if you leave raw milk at room temperature, it creates dramatically more antimicrobial-resistant genes than pasteurized milk."
The study was published in the journal,Microbiome.