Gram stain of meningococci from a culture showing Gram negative (pink) bacteria, often in pairs. Credit: public domain

Prosecutors in northern Mexico blamed private hospitals Monday for contaminated anesthetics that caused a meningitis outbreak that has killed 22 people and sickened at least 71.

Prosecutors in northern Durango state said they have issued seven arrest warrants against the owners or directors of four where the outbreak occurred starting in November.

The warrants charged them with homicide and causing injuries. The office said that tests on a vial of the anesthetic used in the hospitals found no sign of the fungus that caused the outbreak.

Almost all of those infected were women undergoing obstetric procedures. All the patients received a type of anesthesia known as a spinal block. The shots were later confirmed to be contaminated with a fungus.

Many of those sickened were new mothers.

Some had worried the itself had been contaminated in the manufacturing or distribution process; authorities suggested the problem arose at the hospitals.

Authorities had previously closed the four clinics, saying "serious deficiencies" had been found during inspections.

It was the latest scandal for Mexico's woefully under-equipped health care system, which has also had recurring difficulties in supplying medications for children with cancer.

In 2020, 14 people died after a hospital run by Mexico's state-owned oil company gave a drug to dialysis patients that was contaminated with bacteria. More than 69 patients were sickened in that outbreak.