Archive for October, 2009

By Ed Susman

PHILADELPHIA, PA — Researchers said a resistant strain of Stapohylococcus aureau known as USA600 appears to be more lethal than other highly antibiotic-resistant pathogens.

“We found that 8 of 16 patients identified with USA600 bloodstream infections– 50% of the patients infected – died with 30 days of being diagnosed,” said Carol Moore, PharmD, a research investigator in the Division of Infectious Diseases at Henry Ford Hospital, Detroit, MI.

In comparison, about 11% of patients infected with non-USA600 strains died within 30 days. “Actually, we found that most of the patients infected with USA600 died within 15 days of diagnosis,” Dr. Moore said at her late-breaker oral presentation at the 74^th annual meeting of the Infectious Diseases Society of America. Historically, the 30-day mortality rate for MRSA bloodstream infections ranges from 10% to 30%.

Carol Moore, PharmD

She said the strain USA600 contains unique characteristics that may be linked to the high mortality rate. Dr. Moore said researchers are not sure yet whether the strain is more lethal or the health conditions of the patients – 40% of whom were infected in nursing homes – resulted in the high death But they say it is unclear whether other factors like the patients’ older age, diseases or the spread of infection contributed to the poor outcomes collectively or with other factors. The average age of patients with the USA600 strain was 64 years; the average age of patients with other resistant S. aureus strains was 52 years.

“While many methicillin-resistant S. aureus strains are associated with poor outcomes, the USA600 strain has shown to be more lethal and cause high mortality rates,” said Dr. Moore.

“In light of the potential for the spread of this virulent and resistant strain and its associated mortality, it is essential that more effort be directed to better understanding this strain to develop measures for managing it.”

Paul Auwaerter, MD, clinical director of infectious diseases at the Johns Hopkins School of  Medicine, Baltimore, Maryland, said, “This strain of methicillin-resistant S. aureus appears to have some resistance to vancomycin. However, we do have alternatives now such as daptomycin or linezolid.”

Dr. Auwaerter agreed that the UDA600 strain seen by the Henry Ford Hospital doctors is dangerous. “Patients are 5 times more likely to die if they are infected with this strain,” he said.

The study was funded by Henry Ford Hospital.

–10-30-2009

The publishing of a new story from the Infectious Diseases Society of America establishes a milestone for Medical Front Page – our 1,000^th article.

Since going live in February 2009, Medical Front Page reporters and editors have posted articles on all phases of medicine from all corners of the globe.

We thank our correspondents and the 25,000 visitors to our site who have viewed the pages of our website that are updated daily.

Ed Susman

Editor-in-Chief

–10-30-2009

By Ed Susman
PHILADELPHIA, PA – Pregnant women who want to protect their newborns from getting the flu should get themselves vaccinated, researchers said here.
In a study reported here at the 47th annual meeting of the Infectious Diseases Society of America, Marietta Vazquez, MD, assistant professor of pediatrics at Yale University School of Medicine, New Haven, CT, said that if mothers-to-be received a vaccination against influenza the risk of their newborn contracting influenza during the first year of life was reduced by more than 80% when compared with children whose mothers had not been vaccinated while they were pregnant.
But, the percentage of women who receive vaccinations against influenza while they are pregnant “is dismal,” she said during a press briefing.
Dr. Vazquez and colleagues conducted a continuing case-control study of infants admitted to their hospital, starting in 2000. Infants with confirmed influenza were matched with cases of infants admitted for reasons other than influenza infection.

Marietta Vazquez, MD

“Influenza is a major cause of serious respiratory disease in pregnant women and of hospitalization in infants,” she said. “Although influenza vaccine is recommended for pregnant women and children, it is not approved for infants less than 6 months of age. Placental transfer of antibodies to the fetus has been demonstrated in the past, but the few studies having examined the effectiveness of influenza vaccination during pregnancy have had inconsistent findings.”
The goal of the study is to compare the mothers – using both questionnaires and medical records — to see if they were vaccinated during their pregnancy, Vazquez said. Her study assessed the effectiveness of influenza vaccine when given to mothers during pregnancy in preventing hospitalization due to laboratory-confirmed flu in their infants.
She identified 119 infants hospitalized with influenza Just 5% of the mothers of these children had been vaccinated against influenza, the researchers said. On the other hand, 16% of the 172 mothers of control infants, had received influenza vaccinations (P=.002).
Dr. Vazquez said that the differences between the groups translates into an 80.4% effectiveness for reducing the risk of catching influenza for all non-vaccinated children (p=.005). When she analyzed her data and restricted the comparison just to children younger than 6 months – the earliest age at which vaccination is recommended – the effectiveness rate rose to 88.8% (P=.004).

Vazquez said the results might help persuade more women to get vaccinated. “If they’re not getting vaccinated for themselves,” she said, “maybe they’ll do it for their babies.”

–10-30-09