"..This is a significant public health problem. We should be very worried," said Scott K. Fridkin, a medical epidemiologist at the CDC.
Other researchers noted that the estimate includes only the most serious infections caused by the germ, known as methicillin-resistant S taphylococcus au reus (MRSA).
"It's really just the tip of the iceberg," said Elizabeth A. Bancroft, a medical epidemiologist at the Los Angeles County Department of Public Health who wrote an editorial in JAMA accompanying the new studies. "It is astounding."
MRSA is a strain of the ubiquitous bacterium that usually causes staph infections that are easily treated with common, or first-line, antibiotics in the penicillin family, such as methicillin and amoxicillin. Resistant strains of the organism, however, have been increasingly turning up in hospitals and in small outbreaks outside of heath-care settings, such as among athletes, prison inmates and children.