Bacteria

North Harford Middle School has posted a warning and sent a note home to parents this week that its water tested positive Monday for E. coli and fecal coliform bacteria contamination. Black plastic bags were placed over school faucets, and children were encouraged to drink bottled water and clean their hands at hand-washing stations, said the school's PTSA treasurer, Lisa Breece. It was not clear whether any children had become ill from the water. One of the school's vice principals referred questions to a county spokesman, who could not be reached last night.

The safest hamburger might be a well-flipped hamburger, a new study from the Lawrence Livermore National Laboratory in California suggests. Government guidelines suggest cooking ground beef thoroughly to kill bacteria that can cause salmonella and other infections. But some food safety experts have wondered how best to do that without raising levels of amines, chemicals that have been linked to cancer in animals. "These compounds are formed at high temperatures, so the more you cook something the more of these amines you get," said Mark Knize, an analytical chemist who took part in the study.

Workers are ripping out the bacteria-laden carpet in six classrooms at Mount Airy Elementary School this week and replacing it with vinyl tile that will be a less hospitable environment for germs.The bacteria, acinetobacter and enterobacter, are present in animal feces and were probably tracked in on shoes, school officials believe.The first- and second-grade section of the building is built on a concrete slab with no waterproof layer to keep out moisture that seeps up from the ground.Vernon Smith, director of support services for the Carroll County school system, said that may account for why children in that part of the building reported throat and eye irritations.

Swimming has been banned at Hart-Miller Island, the third beach in eastern Baltimore County to be closed this month because of high levels of fecal coliform bacteria. Officials said yesterday that the beach at Hart-Miller Island will be closed through at least the middle of next week, when additional test results are received. Hart-Miller Island, located in the Chesapeake Bay near the mouth of the Middle River, is a popular boating destination. Officials said boating, including kayaking, canoeing and operating personal watercraft, will be allowed.

Some of the bacteria that cause Legionnaire's disease survived a series of cleanings at a Towson office building, and state health officials are now deciding whether the building should be treated again.Karen Stott, a spokeswoman for the Baltimore County Department of Health, said the 700 state and county employees who work at the Investment Building near the intersection of York and Dulaney Valley roads should not fear for their safety."It's still not considered a threat," Stott said. "The levels [of Legionella bacteria]

Baltimore County environmental inspectors will begin searching today for the source of the bacterial contamination that has forced the shutdown of Miami Beach Park's swimming area.County officials said yesterday that the problem, triggered by water-borne fecal coliform bacteria, could have come from waterfowl, area septic tanks or other sources near the beach on the Chesapeake Bay. Results of the survey are expected by the end of the week; a decision on whether to reopen the beach, which closed Monday, could come early next week.

The Maryland Department of the Environment is trying to find out how bacteria are getting into Union Bridge's town well, although water from the well remains safe to drink."

Gunpowder Falls State Park's riverfront beach in Chase will remain closed until at least the middle of next week because of test results showing high levels of fecal coliform bacteria, park and environmental officials said yesterday. After reviewing results of the latest round of testing on water at beaches in eastern Baltimore County, environmental officials said Middle River's Miami Beach also will be closed this weekend. More samples are to be taken at the beaches Monday for tests that will yield results a day later, said David Riter, a technician with the county's Department of Environmental Protection and Resource Management.

Women might be able to protect themselves from HIV infections someday with genetically engineered bacteria that latch onto the virus and keep it from penetrating vaginal tissues, according to research published yesterday. Stanford University scientists are developing the approach, in which they modify a type of naturally occurring bacteria in the vagina to secrete a protein that attracts HIV, the virus that causes AIDS. Once trapped on the surface, the HIV is destroyed by other natural substances in the vagina - such as lactic acid - that are toxic to the human immunodeficiency virus.

Frustrated by a beach closing that has entered its second month, state officials are planning a study to determine the cause of high levels of fecal coliform bacteria in the waters off Gunpowder Falls State Park. Representatives of the state Department of Natural Resources will meet with experts in the state Department of Health and Mental Hygiene and the state Department of the Environment to try to avoid a prolonged closing next summer at the park's Hammerman Area riverfront beach, said John Surrick, a DNR spokesman.