Aug. 22 (UPI) -- A salmonella outbreak that ran from June 2018 to March 2019 was resistant to two drugs commonly used to treat the infection, drawing a warning from the Centers for Disease Control and Prevention on Thursday.
The CDC said in a new report that Salmonella Newport was not responsive to azithromycin and ciprofloxacin, infecting 255 people -- including 60 hospitalizations and two deaths -- in 32 states.
The strain of salmonella could have been started by U.S.-bred beef and Mexico-manufactured soft cheese. This could mean the infection is present in both countries.
"The genetic similarity between isolates from beef in Mexico, beef in the United States, and a steer in the United States strongly suggests that the outbreak strain is present in cattle in both countries," CDC said in the report.
"Because use of antibiotics in livestock can cause selection of resistant strains, the reported 41 percent rise in macrolide use in U.S. cattle from 2016 to 2017 might have accelerated carriage of the outbreak strain among U.S. cattle," the report read.
The outbreak strain had not been identified before 2016, with the CDC saying it emerged recently because it had not been detected in surveillance. It wasn't responsive to ciprofloxacin and had become increasingly resistant to azithromycin, two common antibiotics used to treat salmonella infection.
The CDC estimates about 1.2 million salmonella infections occur each year in the United States, including 450 deaths from the illness. Symptoms of the salmonella include abdominal cramps, diarrhea and fever between 12 and 72 hours of infection. Symptoms typically occur between eight and 72 hours.
"To prevent infection, consumers should avoid eating soft cheese that could be made with unpasteurized milk, and when preparing beef they should use a thermometer to ensure appropriate cooking temperatures are reached: 145 degrees Fahrenheit (62.8 Celsius) for steaks and roasts followed by a 3-minute rest time, and 160 degrees Fahrenheit (71.1 Celsius) for ground beef or hamburgers," CDC said.