The cases show the staph germ, known as methicillin-resistant staphylococcus aureus, or MRSA, has become even more dangerous by causing a shock-like condition.
"The fact that there are three community-acquired staph aureus cases is really scary," says Dr. John Bartlett, an infectious disease specialist at Johns Hopkins University School of Medicine.
The Chicago deaths are described in Thursday's New England Journal of Medicine
Health officials are unclear how the drug-resistant staph causes the shock-like syndrome, but it appears to be rare, according to Dr. Clifford McDonald, an epidemiologist with the federal Centers for Disease Control and Prevention.
Dr. Robert Daum, a pediatrician at the University of Chicago, who co-authored the study, says doctors should be on the lookout for shock-like cases caused by MRSA.
In 1999, drug-resistant staph infections were responsible for the deaths of four healthy children ranging in age from 1 to 13 years old in Minnesota and North Dakota. Since then, doctors have actively kept on eye out for other such infections in their communities.
In the cases reported in Thursday's medical journal, the baby and two toddlers who died were otherwise healthy before they were separately admitted to a Chicago hospital with pneumonia-like symptoms between 2000 and 2004. Doctors believe the children inhaled the germ.
The children died within a week after being hospitalized; autopsies show they suffered from shock and bleeding in the adrenal gland. The infections were caused by MRSA, which is usually not associated with any type of shock.
Until recently, drug-resistant staph infections were thought to be limited to hospitals and other health care settings, where they can easily spread to patients with open wounds, causing serious complications.
Infectious disease specialists now say, in recent years, a growing number of community-acquired resistant staph infections have struck healthy people outside of hospitals.
Doctors in Los Angeles treated 14 people with necrotizing fasciitis, commonly known as flesh-eating bacteria, caused by the resistant germ.
And in Corpus Christi, Texas, doctors have seen community-acquired resistant staph cases jump since the 1990's, from 10 cases a year to over 400 in 2003.
The first Chicago death occurred in 2000, after a 15-month-old girl was diagnosed with severe pneumonia and died eight hours later.
In 2003, a 9-month-old girl was hospitalized with fever and breathing problems, her condition soon deteriorated and she died six days later.
A year later, a 17-month-old boy was admitted with respiratory problems and died the next day.
All three victims' conditions progressed from pneumonia to shock.
