ROME (AP) — Health authorities in northern Italy are investigating whether bacteria in the water supply is behind an outbreak of pneumonia that has afflicted more than 100 people.

The Brescia public health authority issued a general advisory over the weekend for residents to take basic precautions, such as changing water filters or letting water flow for some time before using it. But the notice stressed that the water in the nine hardest hit towns and cities was safe to drink.

Officials were taking water samples and doing epidemiological tests, the results of which were expected in a few days. News reports say some 150 people in Brescia have come down with pneumonia, though the head of the city's health authority, Dr. Carmelo Scarcella, says the number of new cases has fallen.