WEDNESDAY, Sept. 30, 2009 (HealthDay News) -- Bacterial co-infections are common among people who have died of H1N1 swine flu in the United States and probably contributed to their deaths, according to a new federal government study.
Researchers from the U.S. Centers for Disease Control and Prevention analyzed lung tissue samples from 77 people who died of H1N1 flu between May and August this year and found bacterial co-infections in 22 of them (29 percent), including 10 caused by common bacteria called Streptococcus pneumoniae, or pneumococcus. Seven of the co-infections involved Staphylococcus aureus, six involved Streptococcus pyogenes, two involved Streptococcus mitis and one involved Haemophilus influenzae. Multiple pathogens were a factor in four of the cases, the CDC said.
Among those who died, their illness lasted from one to 25 days, with a median duration of six days, the CDC found. Infection with the H1N1 virus was confirmed before death in 41 people and after death in 36.
The 22 people with bacterial co-infections ranged from 2 months to 56 years old and included an equal number of males and females. They came from eight states: California, Hawaii, Illinois, New Jersey, New York, Texas, Utah and Virginia.
Among the other findings in the CDC study:
- Of 18 people for whom information on medical care was available, 14 sought treatment while ill, and eight were hospitalized. At least seven required mechanical ventilation.
- Of the nine people for whom information was available on antimicrobial therapy, seven were treated with antibiotics.
- Previous medical history was available on 21 people, and 16 of them had underlying medical conditions that were known to increase the risk for influenza-associated complications. Also, 15 had conditions that were indications for vaccination with 23-valent pneumococcal polysaccharide vaccine (PPSV23).
- No information was available on the vaccination status of the 22 people with bacterial co-infections.
The findings were published Sept. 30 in an early release of the CDC's Morbidity and Mortality Weekly Report.
The study highlights how important it is for people to get vaccinated against pneumococcus, the researchers said.
"Our influenza season is off to a fast start, and unfortunately there will be more cases of bacterial infections in people suffering from influenza," CDC epidemiologist Dr. Matthew Moore said in a news release from the agency. "It's really important for people, especially those at high risk for the serious complications from influenza, to check with their provider when they get their influenza vaccine about being vaccinated against pneumococcus."
The CDC recommends that children younger than 5 years be given a pneumococcal conjugate vaccination. In addition, the PPSV23 vaccine should be administered to everyone 2 to 64 years old who's considered to be at high risk, and to all people 65 and older.
"The findings in this report also underscore the importance of managing patients with influenza who also might have bacterial pneumonia with both empiric antibacterial therapy and antiviral medications," the CDC study concluded. "In addition, public health departments should encourage the use of pneumococcal vaccine, seasonal influenza vaccine, and, when the vaccine becomes available, pandemic influenza A (H1N1) 2009 monovalent vaccine."
More information
The World Health Organization has more about H1N1 swine flu.
