06/04/2015 05:57 EDT | Updated 06/04/2016 05:59 EDT

NIH suspends making experimental drugs for certain studies after finding 2 contaminated vials

WASHINGTON - The National Institutes of Health is suspending its production of experimental medicines for certain research studies after the discovery of two vials contaminated with fungus.

The NIH says six patients who received different doses made from the original batch in the spring show no signs of illness. Thursday's suspension leaves about 250 people in 46 NIH studies waiting to hear when they will receive other experimental treatments.

A facility at the NIH's research hospital makes modest quantities of experimental drugs for those studies. NIH workers discovered the two contaminated vials in April. Officials say there is no evidence of any other contamination. But last month, Food and Drug Administration inspectors found problems with manufacturing quality practices that NIH must correct.