Meningococcal bug develops quinolone resistance

In some areas of North Dakota and Minnesota, Neisseria meningitidis has developed resistance to quinolone antibiotics. Public health officials recommend that ciprofloxacin, the drug from this family commonly prescribed to reduce the risk of illness in healthy people who have been exposed to this bacterium, no longer be used for this purpose.

The officials also want physicians outside the region to be alert to the possibility that the medication may not have the desired effect, according to statements issued by health departments in those states and a report in the Feb. 22 Morbidity and Mortality Weekly Report.

"Resistance may rise quickly," said Ruth Lynfield, MD, state epidemiologist for the Minnesota Dept. of Health. "People need to consider susceptibility testing for invasive meningococcal isolates."

Officials issued this advice in response to three cases determined to be quinolone-resistant. The circumstance has been documented elsewhere in the world, but these are the first cases in North America. However, because many laboratories don't carry out resistance testing, there may be many more cases here that have not been detected.

"We might not be picking them up. That's scary," said Neil Fishman, MD, vice president of the Society for Healthcare Epidemiology of America.

Physicians still have options, although less desirable ones. Other long-recommended drugs, rifampin and ceftriaxone, still can be used, and azithromycin has been added to the list when resistance to ciprofloxacin is a possibility. But experts are worried about losing one of the easier options for situations where prevention is critical.

For instance, ciprofloxacin used as prophylaxis needs to be taken only once. Rifampin has to be taken twice a day for two days, and ceftriaxone has to be injected. Azithromycin needs to be taken only once, but data supporting its effectiveness in this situation are more limited than for the other drugs.

"For certain types of problems, [quinolones] are very good and easily tolerated. They're a valuable class of antibiotics," said David McNamara, MD, an infectious disease specialist at MeritCare Health System in Fargo, N.D.

But the experts also say the situation's true take-home message is twofold: Prevention of meningitis is particularly important, as is the judicious use of antibiotics.

This drug-resistant strain is a variety of the bacterium that the meningitis vaccine does not protect against, but public health officials are taking the opportunity to encourage increasing use of it for those recommended to receive it. This list includes those ages 11 to 18 and college freshmen living in dormitories.

They also are taking the opportunity to call for more careful use of antibiotics, particularly since this bacterium is not the only one in recent memory to become resistant to this class of drugs. For example, in April 2007 the Centers for Disease Control and Prevention announced that quinolones no longer could be used against Neisseria gonorrhoeae, a far more common cousin of Neisseria meningitidis, because resistance was so widespread.

"When you start seeing commonly used antibiotics lose effectiveness against uncommon organisms, that's a real concern," Dr. McNamara said. "Quinolones used to be a really good option."

Tackling antibiotic resistance has long been the focus of public health and medical society efforts. The American Medical Association has worked to educate physicians about appropriate antibiotic use and the need to inform patients about the consequences of antimicrobial resistance. The Association also encourages scientific research into this continuing problem.

"We really do have to pay attention to appropriate use of antibiotics, but that's a hard thing to do," said Dr. Fishman, who is also the hospital epidemiologist at the University of Pennsylvania in Philadelphia. "It takes one minute to write a prescription, and 15 or 20 not to write a prescription. Evidence shows that would be time well spent."

Public health officials in North Dakota and Minnesota are working with the CDC to determine the number of people who carry drug-resistant Neisseria meningitidis in those states. Federal health officials are assessing its reach nationally.