WEDNESDAY, Feb. 25 (HealthDay News) -- The first U.S. cases of meningitis bacteria resistant to a widely used antibiotic have caused public health agencies to increase surveillance efforts, change preventive measures in one area of the country, and emphasize warnings about overuse of all antibiotics.

A toddler in North Dakota who recovered, a Minnesota adult who died and a Minnesota college student who survived were found to have been infected with meningitis bacteria resistant to ciprofloxacin, said a report in the Feb. 26 issue of the New England Journal of Medicine.

"Ciprofloxacin resistance had not been described in the United States," said report lead author Dr. Henry M. Wu, an officer with the federal Centers for Disease Control and Prevention's epidemic intelligence service. "When these cases presented, it became very important to investigate."

About 800 to 1,500 cases of bacterial meningitis occur each year in the United States, Wu said. The mortality rate is 10 percent to 15 percent, and "there are high rates of permanent disability among the survivors," he said.

A diagnosis of bacterial meningitis calls for immediate use of an antibiotic to protect anyone who has been in close contact with the patient. Ciprofloxacin is perhaps the most widely used antibiotic for bacterial meningitis, but its use for that purpose has been stopped in Minnesota and North Dakota to prevent the spread of the resistant strain, Wu said.

"After these three cases, we have increased antimicrobial testing," he said. "There has since been a single case in California, but we have not changed our recommendations for California. We have been increasing the number of isolates we test for resistance, but so far we have not detected any further cases."

The two alternatives to ciprofloxacin are the antibiotics rifampin and ceftriaxone, Wu said. The Minnesota student who recovered was treated with ceftriaxone, which must be given by injection. Ciprofloxacin is preferred for preventive treatment, because it can be taken orally, and "it doesn't involve multiple doses," he said.

Dr. Ruth Lynfield, Minnesota's state epidemiologist who took part in the investigation, said, "The fact that we now see emergence of ciprofloxacin resistance in this bacterium is very troubling. This underscores the importance of using antibiotics appropriately, so we don't overuse them."

Lynfield said health officials are worried about a repeat of the experience with gonorrhea, in which antibiotic resistance spread quickly after it first occurred. "We do think that it is related to overuse of antibiotics in the community," she said.