Johnson & Johnson said on Thursday it is recalling some lots of infants' and children's Tylenol because of a possible bacterial contamination of the popular pain and fever treatment.

Tylenol products being recalled were manufactured between April and June 2008, the diversified healthcare giant said.

The company identified 21 varieties of the products, which come in various flavors and forms, and 57 different lot numbers, affected by the recall..

The company said it has contacted wholesalers and retailers about the recall, which affects only the United States. It was not immediately clear how widely distributed the 57 affected lots were within the United States.

In a letter dated September 18, J&J unit McNeil Consumer Healthcare said that after consulting with the U.S. Food and Drug Administration, it initiated the voluntary recall as a precaution.

The company said that one of the inactive ingredients did not meet internal testing requirements and Burkholderia cepacia, or B. cepacia, bacteria were detected in a portion of raw material that was not used in the finished product.

However, it was decided, as a precaution, to recall all product that utilized any of the raw material manufactured at the same time as the raw material that tested positive for the bacteria, the letter said, emphasizing that no bacteria were found in the finished product, which met all specifications.

J&J said the likelihood of a serious medical problem arising from the recalled product was remote.

The FDA is working closely with the company to monitor this recall, agency spokeswoman Sandy Walsh said.

There are no adverse events reported by patients using this product, she added.

Health consequences of B. cepacia infections could be severe in high-risk patients, such as those with underlying pulmonary disease, cystic fibrosis or compromised immune systems.

Johnson & Johnson shares closed down 5 cents at $60.72 on the New York Stock Exchange.