Officials from the Prince George's Hospital Center brief reporters during an evacuation of the neonatal intensive care unit earlier this year.

The Prince George’s Hospital Center is closing its neonatal intensive care unit for the second time this year following another bacterial outbreak among its patients.

Dimensions Health Care Systems, the nonprofit organization that runs the hospital, said in a statement on Wednesday that all five tiny patients will be transferred from the unit after two were found to have tested positive for the Pseudomonas bacterium.

“At this time there is no environmental indication or defined cause for the latest bacterium presence,” Dimensions said in the statement.

Chief Operating Officer Sherry B. Perkins called the germ a “complex epidemiological case,” but said experts are working closely with the hospital to get rid of it.

This outbreak comes one month after the hospital reopened the NICU, after state and hospital officials implemented safeguards to prevent Pseudomonas from recolonizing in the hospital’s water system. The waterborne germ is notoriously difficult to eradicate.

Pseudomonas can be deadly for people with compromised immune systems, such as babies in the NICU. It is fairly common in tap water and can spread by health care workers’ hands and insufficiently sterilized medical equipment.

The bacteria was first discovered in the Cheverly hospital in early August, when officials said routine nasal swabs from several infants detected its presence.

At that time, nine NICU patients were transferred to Children’s National Medical Center in the District.

It took nearly two months for the hospital and state epidemiologists to discover the source of the bacteria: the plumbing supplying water to the NICU. They removed sinks that had harbored Pseudomonas, installed filters on faucets and treated the water.

State health officials said their agency was informed of the latest outbreak on Sunday.

Dimensions did not respond to additional questions regarding how the bacteria was detected or whether any children were sickened by the outbreak.

It is unclear where the patients were being transferred.