ATLANTA - Four children from Minnesota and North Dakota died of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) between 1997 and 1999, despite having established risk factors.
Therefore, the Centers for Disease Control and Prevention (CDC) is reminding physicians that MRSA can cause infections in healthy young patients and is resistant to ß-lactam antibiotics.
"These cases suggest that MRSA is an important emerging infectious disease in the general population, not just in traditional high-risk groups such as hospitalized patients, those in long-term care facilities and injection drug users," said Timothy Naimi, MD, MPH, medical epidemiologist at the CDC, based at the Minnesota Department of Health.
Previously, community-acquired MRSA infections were limited to patients residing in long-term care facilities, health care workers and injection drug users. "These four cases, however, are different because they involved healthy children from the general population."
Community-acquired MRSA infections have been identified at a Chicago pediatric hospital, in day care centers and among minority communities in other countries, according to a recent Morbidity and Mortality Weekly Report.
Unlike nosocomial MRSA isolates, community-acquired isolates from patients without MRSA risk factors are generally multidrug susceptible, except to ß-lactams, and have distinctive molecular characteristics.
"The class of antibiotics to which these MRSA are resistant includes all of the b-lactam antibiotics, including the entire penicillin family of antibiotics as well as the cefazolin family," said Naimi, who added that these antibiotics are frequently used in outpatient clinics and hospitals, where MRSA infections are usually seen.
The strains isolated from the four patients, however, seem to have different antimicrobial susceptibility patterns and pulsed-field gel electrophoresis characteristics than typical nosocomial MRSA strains, according to the CDC.
"The good news is that all four of these isolates were susceptible or sensitive to nearly all other classes of antibiotics that were tested," said Naimi. This is good news for pediatricians, he said, because there are plenty of other oral and intravenous antibiotic alternatives available to treat MRSA infections. He stressed that these four cases should not lead to an increased use of vancomycin.
However, it is hoped that these community-acquired strains of MRSA will not require routine use of vancomycin, said Naimi. "This is something very important because vancomycin use has a lot of problems in terms of developing antibiotic resistance."
In July 1997, a previously healthy 7-year-old black girl from urban Minnesota presented with a temperature of 103° F and right groin pain. She underwent surgical drainage for an infected right hip and was treated with cefazolin.
On day three, antimicrobial therapy was changed to vancomycin when blood and joint fluid cultures grew MRSA, and the patient underwent another hip drainage.
She developed respiratory failure and was mechanically ventilated. Her course was complicated by acute respiratory distress syndrome, pneumonia and an empyema that required chest tube drainage. She died from a pulmonary hemorrhage after five weeks of hospitalization.
The MRSA strain isolated from her blood, hip joint and sputum was susceptible to multiple antibiotic classes. Autopsy revealed bilateral bronchopneumonia with abscesses. None of her family members resided in long-term care facilities or worked in health care settings.
In February 1999, a previously healthy 12-month-old white boy from rural North Dakota presented with bronchiolitis, vomiting and dehydration. He had a temperature of 105.2° F and a petechial rash.
Chest radiograph revealed an infiltrate in the right lung consistent with pneumonitis. On day two, he was diagnosed with a large right pleural effusion and transferred to the intensive care unit where a chest tube was inserted and vancomycin and cefuroxime (Ceftin, Glaxo Wellcome) treatment were initiated. He died the following day after developing severe respiratory distress and hypotension. Cultures from the patient's pleural fluid and blood grew multidrug-susceptible MRSA.
Autopsy revealed acute necrotizing pneumonia with extensive hemorrhage and numerous gram-positive cocci in the right lung. None of the child's family members were health care workers, resided or worked in long-term care facilities or were known injection drug users.
His two-year-old sister, however, was treated for a culture-confirmed MRSA buttock infection three weeks earlier, and the isolates from he and his sister had identical antibiotic susceptibility profiles.
The other deaths occurred in two children, 16 and 13 months of age. An autopsy of the 16-month-old Native American girl from rural North Dakota revealed multiple small abscesses of the brain, heart, liver and kidney and cultures of meninges, blood and lung tissue grew MRSA. The autopsy of the 13-year-old white girl from rural Minnesota revealed that blood, sputum and pleural fluid grew multidrug susceptible MRSA.
The four cases were in rural and racially diverse areas, suggesting that MRSA colonization may be widespread, particularly in this region of the United States, according to the CDC. The extent of MRSA infection, however, is unknown.
It is unclear how to limit the spread of MRSA and whether it is feasible to decolonize selected high-risk people, according to the report.
How frequently these types of infections occur and where they occur need to be better defined, said Naimi. "I think it is very important to note that these were cases that occurred in one geographic area of the country. We need to do a better job at finding where this bacteria is living in the general population, and we need to do a better job of defining the full range of infections that it might cause."
Naimi concluded that the root of the drug resistant bacteria problem is the excessive and inappropriate use of antibiotics among pediatricians, especially in regard to colds, common bronchitis and marginal ear infections. "Pediatricians should culture when appropriate and redouble their efforts to use antibiotics appropriately so we can decrease the tendency for these resistant organisms to proliferate," he said.
For more information:
- CDC. Four pediatric deaths from community-acquired methicillin-resistant Staphylococcus aureus- Minnesota and North Dakota, 1997-1999. MMWR 1999;48(32):707-710.
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