A second top Los Angeles hospital has reported an outbreak of drug-resistant "superbug" infections, and dozens more potential exposures, from procedures performed with a fiber-optic instrument called a duodenoscope.

The notice from Cedars-Sinai Medical Center of four such infections and 67 more patients who were at risk coincided with a hospital in Hartford, Connecticut, reporting a similar outbreak involving at least five infections and more than 280 potential exposures.

The Cedars-Sinai cases, like the larger number of infections and potential exposures reported last month at the UCLA Ronald Reagan Medical Center in Los Angeles, involved a family of germs called carbapenem-resistant Enterobacteriaceae, or CRE.

The bacteria identified on Wednesday in the Hartford Hospital outbreak was a drug-resistant strain of E.coli.

But the procedure and instrument implicated at all three hospitals were the same - an endoscopic retrograde cholangiopancreatography, or ERCP, performed with a duodenoscope.

The Food and Drug Administration, meanwhile, issued an updated safety alert for duodenoscopes, urging medical providers to inform patients of the risks, including possible transmission of infection, associated with the use of such instruments.

The alert also puts providers on notice to report any infections they suspect were caused by problems with the scopes to the manufacturer and the FDA.

The latest flurry of infections has raised new questions about whether manufacturers' recommendations for disinfecting duodenoscopes are sufficient to protect patients.

The complex design of the instrument - flexible tubes that are threaded down the throat and stomach to the top of the small intestine to drain fluids from blocked pancreatic and bile ducts - may hinder proper cleaning, the FDA has warned.

A senior FDA official said this week that manufacturers' own tests of disinfection measures they recommend contained flaws that rendered those cleaning procedures unreliable.

Makers of the devices include such camera companies as Olympus Corp (7733.T), Fujifilm Holdings Corp (4901.T) and Pentax.

Olympus was the maker of the single duodenoscope linked to all 71 patients of concern at Cedars-Sinai, from August 2014 to February 2015, and of two suspect scopes tied to 179 potential exposures dating back to October at UCLA.

Seven of UCLA patients were confirmed to have been infected, and two of them had died.

One of the four infected Cedars-Sinai patients died from "an underlying disease," not from the bacteria, as the infection had by then been cleared, the hospital said in its statement.

Hartford Hospital said it found five or six of its patients had contracted drug-resistant E.coli last year from two duodenoscopes used in 281 more procedures, leading doctors to conclude that those additional patients may have been exposed.

Both privately run Cedars-Sinai and UCLA, a public hospital, say they were offering potentially exposed patients free home-testing kits. The two facilities also said they have begun using enhanced disinfection procedures, above and beyond the manufacturer recommendations.

Duodenoscopes have been associated with episodic infections for more than a decade. But an increasing number of germs have developed a resistance to antibiotics, making them potentially more dangerous and difficult to treat.