The bacterial disease is believed to have killed at least 31 people in the northwestern area of Tuscany.

Authorities in Tuscany, home to some of Italy's most visited tourist attractions, have stepped up hospital controls after a deadly outbreak of the superbug that first surfaced in Delhi.

The antibiotic-resistant killer has shown "significant diffusion in the northwestern area of Tuscany" since November 2018, infecting at least 75 people, local health authority ARS said.

The bacterial disease is believed to have killed at least 31 people in 17 different hospitals since then, Italian media reported Thursday.

More than 31 cases were reported in Pisa, home to the famous leaning tower.

Superbug NDM-1 (New Delhi metallo-beta-lactamase 1) sparked a global panic when it was found in New Delhi in 2010 and showed resistance even to carbapenems, a group of antibiotics often reserved as a last line of defence.

The European Centre for Disease Prevention and Control in June issued a rapid risk assessment after a "large outbreak" of the superbug in Tuscany.

It warned of possible cross-border infections, "especially since the affected area is a major tourist destination."

Tuscany's health authority said "the ability to resist antibiotics makes these bacteria dangerous, especially in vulnerable patients, already affected by serious pathologies or immunosuppressed."

As a result, hospitals in the region have "stepped up procedures for the prevention and control of infections in health facilities," it said.