Annual Meeting of the Infectious Diseases Society of America and the HIV Medicine Association

An HIV mystery
Less than 1 percent of HIV patients have the uncanny ability to suppress the virus for years, earning them the name “elite controllers” because they rarely develop AIDS. But researchers now report that some of these people have a chink in their immune defenses after all. In most HIV patients, the virus depletes essential immune cells called CD4 T cells. Elite controllers continually rebuild supplies of these cells. But sometimes their ability to restock these cells fails, and they develop AIDS as their CD4 T cell numbers plummet. For reasons that aren’t clear, these people get sick despite the fact that the rest of their immune systems continue to suppress HIV to practically undetectable levels, reported physician Mathias Lichterfeld of Harvard Medical School.  This raises a clinical problem because HIV drugs work by knocking down virus replication — which is already suppressed in elite controllers. Thus, the drugs don’t help them, Lichterfeld says. —Nathan Seppa

C. diff vaccine progresses
An experimental vaccine against the bacterium Clostridium difficile has cleared an early hurdle. The vaccine is designed to boost a person’s ability to produce antibodies against two toxins, dubbed A and B, made by C. difficile. The toxins cause colitis that is marked by fever, diarrhea and cramps. Researchers gave 72 adults three injections each of the vaccine over 56 days in low, medium or high doses. Another 24 volunteers got placebo shots. Blood samples drawn six months after the last shot showed that nearly all the vaccinated people had developed an antibody response against toxin A, and more than half did against toxin B. C. difficile infections most commonly spread in hospitals among people on antibiotics. If the vaccine passes further tests, the target group for it would be older people who frequently visit hospitals or who are planning to do so for an upcoming medical procedure, said physician and vaccinologist Ginamarie Foglia of the drug company Sanofi Pasteur, who reported the data. —Nathan Seppa

Blood transfusions can pose risks
Hospitalized patients with infections are more prone to develop sepsis — a dangerous immune overreaction — if they get a blood transfusion, researchers report. Transfusions have long been thought to dampen the immune response and possibly open the door to infection, said epidemiologist Mary Rogers of the University of Michigan in Ann Arbor. She and her colleagues identified 969 people who were hospitalized from 2000 to 2008, all of whom had a urinary tract infection. In 299 of those people, the infection spread to the blood and caused sepsis. The chances of developing sepsis were nearly five times greater if a person underwent a transfusion of red blood cells beforehand, the scientists found. Nearly one-third of the people who developed sepsis died, compared with only 4.5 percent of those who didn’t have the immune reaction. Red blood cells stored the longest were associated with a greater risk of blood infection and sepsis. —Nathan Seppa

Bacteria, bacteria everywhere
The current quality of hand-washing in restrooms isn’t up to par, suggested epidemiologist Lennox Archibald of the University of Florida in Gainesville. A sampling of common surfaces and handles in public restrooms revealed substantial amounts of well-known bacterial culprits such as Staphylococcus aureus, Escherichia coli and others. Archibald’s team took swabs from four airplane restrooms and 18 restrooms in U.S. restaurants, offices, libraries, hotels and other public establishments, noting that many microbe-laden surfaces were those typically touched after hand-washing. “I don’t want the public to get paranoid,” Archibald said. “But I think in the current era of [methicillin-resistant S. aureus] and community-acquired infections, you just need to wash your hands carefully.” —Nathan Seppa