Health officials said the child, from Tulsa, Okla., was infected with Cronobacter sakazakii, but has now fully recovered.
An Illinois child also rebounded from the infection, but a 10-day-old baby from Missouri died.
The Missouri child's death was initially linked to Enfamil powdered infant formula.
Health officials said the baby in this new case out of Oklahoma had not consumed Enfamil.
The makers of Enfamil said they've tested the same lot fed to the Missouri baby and found no sign of the bacteria.
U.S. officials are awaiting results from their own testing of powdered formula and distilled water used to prepare it.
Barbara Reynolds, a spokeswoman for the Centers for Disease Control and Prevention, said the cases have occurred in roughly the same region of the country, and at this point, it is not clear if they are connected.
Symptoms can include irritability, lethargy, fever, vomiting and seizures. The infection can be treated with antibiotics, but it's still deemed extremely dangerous to premature babies and babies less than 1 month old
An estimated 40 percent of illnesses from the bacteria end in death.
There is no law that requires cases to be reported, but the CDC gets roughly four to six reports of Cronobacter sakazakii each year.
There have been 10 this year, but that doesn't necessarily mean cases are increasing. Attention over the Missouri death just may have prompted more reporting in the past, health officials said.
The bacteria is found naturally in the environment and in plants such as wheat and rice, but it has also been traced to dried milk and powdered formula in the past. Powdered infant formula is not sterile, and experts have said there are not adequate methods to completely remove or kill all bacteria that might creep into formula before or during production.
After initial suspicion landed on Enfamil, national retailers including Wal-Mart Stores Inc., Walgreen Co., Kroger Co. and Safeway pulled a batch of the powdered infant formula from their shelves.
The Associated Press contributed to this report.