This superbug, known as Carbapenem-Resistant Enterobacteriaceae (CRE), is a type of antibiotic-resistant bacteria. This illustration depicts the bacteria moving through the bloodstream with flagella. There is no evidence that the nightmare strains have swapped the mcr-1 gene into their genomes, experts said.

NEW YORK — State and federal health officials are investigating a possible “patient zero” in New York who may have been infected with bacteria that ferried genes resistant to the final drugs on pharmacy shelves, health department officials confirmed last week.

The patient, who wasn’t identified by name or place of residence, was apparently infected last year with E. coli that carried a gene known as mcr-1. New York’s probable case of a highly potent form of drug resistance marks the second such case in the country. The resistance gene first emerged in China, experts said.

Hints about a New York link to the resistance gene from China were contained in a study reported in the journal Antimicrobial Agents and Chemotherapy, a publication of the American Society for Microbiology. The report, however, was abruptly withdrawn late Monday afternoon by its editors. A spokeswoman for the journal said the research was “put on hold” because scientists needed to further verify their data.

But about a half-hour after the report’s withdrawal, state health officials confirmed that an investigation involving the resistance gene is underway in New York. A separate case is being investigated in Pennsylvania.

Dr. Bruce Polsky, chairman of medicine at Winthrop University Hospital in Mineola, said mcr-1 is an infinitesimal snippet of DNA that confers a powerful form of antibiotic resistance. The gene enables bacteria to repel the drugs colistin and polymixin B, the last ones on the shelf.

“Mcr-1 confers what we call pan-resistance, which means resistance to all known antibiotics,” said Polsky, who was not involved in the research.

Colistin is an antique antibiotic that Polsky said was resurrected from the 1950s and put back into service in recent years to combat so-called “nightmare bacteria.”

The nightmare bugs — also known as CRE for carbapenem-resistant enterobacteriaceae — thwart the drug class known as carbapenems, a half-dozen modern antibiotics frequently referred to as the drugs of last resort. Now, bugs equipped with mcr-1 have moved a step beyond that. There is no evidence that the nightmare strains have swapped the mcr-1 gene into their genomes, experts said Monday.

State health officials told Newsday in an email that hospitals, nursing homes, diagnostic and treatment centers throughout New York were informed in a health advisory about the drug resistance gene on June 16. There was no news release to inform the public, however. The statement also said New York health authorities were notified of the emerging form of drug resistance by officials at the Centers for Disease Control and Prevention.

The CDC routinely studies bacterial samples from hospitals nationwide as part of the agency’s broad-scale surveillance program for highly infectious pathogens. Health department officials said the bacterial sample “is currently being investigated and will require confirmatory testing.”

Polsky said mcr-1 emerged recently in China in the human population and has spread throughout pig herds that are farmed for their meat. The bacteria are shuttled around the world, he said, with the global movement of humans and animals.

Polsky said mcr-1 exists on a mobile ring of genes that bacteria pass among themselves, called a plasmid. “Once it’s here in plasmid form it is easy to imagine how it can move from one place to another.

“The good news is the vast majority of E. coli and other Gram negative bacteria do not have the mcr-1 plasmid,” Polsky said, referring to related microbial strains.

State health officials, meanwhile, said the health department’s division of epidemiology “has an active surveillance program for all forms of bacterial drug resistance.”

The Wadsworth Center, the state’s laboratory, uses a range of molecular technologies to detect antibiotic resistance, officials said.