Drug-Resistant Infections Gaining Traction in U.S.

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by Nicole Ostrow

October 17, 2007

The most frequent type of drug- resistant skin infections among people going to emergency rooms is about three times more prevalent than U.S. health officials thought, according to new research.

There were 31.8 cases of methicillin-resistant Staphylococcus aureus, or MRSA, for every 100,000 persons in the U.S. in 2005, with the highest rates among those 65 and older, researchers said. A second study found that ear infections in children caused by a resistant strain of a germ that can lead to pneumonia and meningitis may also be gaining traction.

Both reports in this week's Journal of the American Medical Association suggest there is a growing need for new medicines to treat infections that are increasingly causing deadly illness in the community and hospitals.

``We hope that there are more pressure and more incentives to develop more and more useful antibiotics for all generations,'' said Elizabeth Bancroft, a medical epidemiologist at the Los Angeles County Department of Public Health who wrote an editorial accompanying the studies in the journal.

The MRSA study is the first to document nationwide prevalence for a germ that can be deadly when infections enter the body through a wound or opening, Bancroft said in an Oct. 15 telephone interview.

The report by researchers at the U.S. Centers for Disease Control and Prevention in Atlanta, found 8,987 cases of invasive MRSA at nine areas in the U.S. between July 2004 and December 2005. About 18 percent of the cases, or 1,598, resulted in death.

94,360 Cases

The researchers, led by R. Monina Klevens, adjusted their findings by age, race and sex to determine incidence rates. Based on those numbers, the CDC estimated that 94,360 invasive MRSA infections occurred in the U.S. in 2005 and that those infections were associated with 18,650 deaths.

In 2000, the CDC estimated that there were 31,440 U.S. cases of MRSA based on hospital discharge codes, the researchers said.

The newest numbers for estimated deaths exceed those attributed to AIDS in the U.S. in 2005, Bancroft said. About 17,000 people died of AIDS that year, according to the CDC.

``We clearly need some better vaccines for pneumococcal disease and, ideally, a vaccine for staph,'' Bancroft said.

A high school student in southwest Virginia died from an MRSA infection yesterday, prompting authorities to close all 21 schools in Bedford County for cleaning, the Associated Press reported today.


Many hospitals in the U.S. and Europe are testing all their patients for the drug-resistant germs and isolating those who have the bacteria on their skin or in their noses until they can be treated or disinfected. The results may spur more legislation in Illinois and some other states to require hospitals to perform the screening routinely.

The drug-resistant ear infections reported in the journal involve a form of the pneumococcus germ, called Legacy, that first surfaced during the 2003-2004 flu season. Between September 2003 and June 2006, nine cases of the new strain were reported in Rochester, New York, out of 1,816 children treated for ear infections.

While the number of children with the drug-resistant diagnoses was small, the researchers caution that the bacteria could spread to other communities and invade the lungs or bloodstream leading to pneumonia or meningitis. They recommend doctors learn how to test for the bacteria and not over prescribe antibiotics and urge parents to get their children vaccinated with Wyeth's Prevnar.

Popping Up Elsewhere

``This winter we are concerned that this Legacy strain may show its face not only in Rochester but pop up in other parts of the country,'' said Michael Pichichero, the study's lead author and a professor at the University of Rochester Medical Center in New York state, in an Oct. 12 telephone interview. ``Doctors need to be aware that it could be there.''

Prevnar includes seven pneumococcal strains out of 90. They were chosen because they accounted for the majority of the pneumococcal infections in the U.S. in children under two.

The vaccine has helped reduce visits to doctors for ear infections by 20 percent in children under the age of two, according to Madison, New Jersey-based Wyeth.

The company is developing a vaccine that covers 13 pneumococcal strains, including the drug-resistant 19A strain that was seen in Rochester, and plans to seek U.S. regulatory approval in early 2009, said Kim Center, Wyeth's director of global medical affairs, in an Oct. 12 telephone interview.

1,816 Children

In the study, researchers performed an ear tap in 212 of the 1,816 children treated for ear infections.

Of the nine cases infected with the drug-resistant strain, four children received tubes in their ears, which help to prevent infection by allowing air into the ear. The other five children were given Johnson & Johnson's Levaquin, which is only approved for use in adults.

``We will not treat a child with Levaquin unless we know for sure that they have a super bug,'' said Janet Casey, an author of the study in an Oct. 12 telephone interview. ``We cannot afford to lose this drug and widespread use of this drug will cause resistance.''

All of the children in the study were vaccinated with Prevnar. The researchers found that the strains not included in the Prevnar vaccine were becoming more numerous and more resistant to standard antibiotics.

Children receive Prevnar in four doses, starting around two months old. The fourth shot is given between 12 months and 15 months, according to the prescribing label. The vaccine had 2006 sales of $1.96 billion.