U.S. Sen. Bob Menendez speaks during a news conference, Wednesday,...

U.S. Sen. Bob Menendez speaks during a news conference, Wednesday, April 1, 2015, in Newark, N.J. Menendez, the top Democrat on the U.S. Senate Foreign Relations Committee, was indicted on corruption charges, accused of using his office to improperly benefit an eye doctor and political donor. Credit: AP

Politicians have always found their way to trouble by associating with fraudsters, wiseguys, thieves and prostitutes.

But associating with doctors?

In Newark federal court yesterday, Sen. Robert Menendez (D-N.J.) pleaded not guilty to corruption charges including bribery. The criminal counts involve his dealings with Salomon Melgen, a Florida eye doctor and friend of the senator's.

Judging by official accounts, Melgen does not just spend his days asking patients which lens they see better through and checking for glaucoma.

The feds have charged Melgen in connection with efforts to get visas for his overseas girlfriends, deluxe getaways and lavish gifts. Melgen also allegedly had the senator pulling strings for him with bureaucrats in a high-stakes dispute over his Medicare billings.

The ophthalmologist, who also pleaded not guilty, has attracted scrutiny before. In 2012, his Melgen Retina Eye Center, with offices in West Palm Beach, received $20.83 million from Medicare, making him the program's highest-paid doctor, according to published reports.

The case happens to emerge weeks after another physician -- one who is not charged with any wrongdoing -- drew the spotlight in another federal case against another politician, Assemb. Sheldon Silver (D-Manhattan), who was forced to step aside as speaker.

Dr. Robert Taub is a longtime researcher and clinician specializing in asbestos-related cancer known as mesothelioma. Federal officials said Silver routed $500,000 in state grants to the Columbia University Mesothelioma Center then run by Taub.

In turn, officials charged, it was arranged that Taub would refer his patients to the law firm Weitz & Luxenberg to sue over the hazardous exposure. Silver was of counsel to the Weitz firm.

Taub -- still widely reported to be respected by patients and peers -- was removed as head of the university center. He's identified as "Doctor 1" in a criminal complaint against Silver filed by U.S. Attorney Preet Bharara's office. Silver denies all allegations.

The practice of physicians referring patients to lawyers, meanwhile, was raising discussion even before this case emerged.

Nearly three years ago David Rosen, a former chief executive at Medisys, a Queens nonprofit hospital group, was sentenced to 3 years in prison on bribery conspiracy charges. He figured in payoff cases involving three New York State legislators, including former Democratic Assemb. Carl Kruger, now serving a 7-year prison term. A friend of Kruger, gynecologist Michael Turano, pleaded guilty to one conspiracy count in the complex case.

This week also brought a reminder that some doctors manage to get jammed up without politicians' help. Alleging a conventional-sounding scheme to defraud Medicaid by concocting false claims, Brooklyn District Attorney Kenneth Thompson charged 23 people -- nine of them physicians.

Any corruption afflicting the medical field stands out because of its high calling.

As for elected officials, instances of sleaze may be chronic and incurable. But at least we're accustomed to those.