Researchers in the U.S. say that it is not just in hospitals that the so-called "superbugs" present a problem.
They say drug-resistant bacteria have spread to the urban poor in the U.S. and are now infecting more people in community settings such as prisons and public housing, and the problem is no longer confined to hospitals.
According to the researchers, crowded living conditions in public housing and jails may accelerate the person-to-person spread of the infections; they say such infections rose almost seven-fold in recent years in some Chicago neighbourhoods.
It was once the case that superbugs were seen mainly in hospitals and nursing homes and confined to vulnerable patients, but they have recently appeared amongst athlete groups, prisoners and people who have illegal tattoos and the problem has emerged in community settings around the world.
Superbug methicillin-resistant Staphylococcus aureus (MRSA) are staph germs which can cause skin infections that in rare cases have led to pneumonia, bloodstream infections and a painful, flesh-destroying condition.
MRSA is tricky to manage because the bacteria have developed resistance to the penicillin drug family.
Over a five-year period, the researchers at Chicago's Rush University Medical Center found a seven-fold increase in drug-resistant staph infections that had been contracted outside of any hospital.
They estimate that the rate of infection rose to 164 cases per 100,000 people in 2005, up from 24 cases per 100,000 in 2000.
After analyzing 518 people who received treatment for community-contracted infections, the researchers found two significant risk factors: incarceration in a jail or prison, and living in public housing projects.
Other risk factors included intravenous drug use, living in overcrowded housing, playing certain sports, tattooing and poor hygiene.
The U.S. Centers for Disease Control and Prevention (CDC) says drug-resistant infections contracted in U.S. hospitals kill 90,000 people annually and cost $4.5 billion.