Sept. 17, 2007 (Chicago) -- Since the 2000 introduction of the pneumococcal vaccine to prevent ear infections in children, a superbug that is resistant to all the antibiotics approved to treat the condition has emerged, researchers report.
Children who carry the superbug develop particularly agonizing middle ear infections and often need surgical insertion of pressure-equalizing tubes in the ears, says Michael Pichichero, MD, a pediatrician and vaccine researcher at the University of Rochester in Rochester, N.Y.
Pneumococcal bacteria cause 30% to 55% of kids' ear infections. More than four out of five kids get at least one ear infection by the age of 3. It's the most common reason doctors give antibiotic drugs to children.
Vaccines and Middle Ear Infections
In 2000, a pneumococcal vaccine became commercially available for children under age 2. Sold as Prevnar, the pneumococcal vaccine attacks seven strains of the bacterium Streptococcuspneumoniae that can cause ear infections.
In the early years following its introduction, the pneumococcal vaccine cut middle ear infections by 20%, Pichichero says.
But by 2003, problems began to emerge, he tells WebMD. That’s when doctors began to see kids with ear infections caused by strains of S. pneumoniae other than the seven included in the vaccine.
The new study was presented here at a meeting of the American Society for Microbiology.
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Antibiotic-Resistant Bacteria Strain
The study included 162 children with recurrent ear infections. All of the children had received the pneumococcal vaccine.
All the children underwent ear taps, a procedure during which doctors put a needle into the eardrum to draw out infected fluid so they can examine the bacteria.
They found that 59 children carried the S. pneumoniae bacterium.
Of these, nine children carried a new strain called 19A that is not included in the vaccine and proved resistant to all FDA-approved antibiotics for ear infections in children.
"Children infected with this strain were unsuccessfully treated with two or more antibiotics," Pichichero says.
A 'Particularly Troubling' Strain
Keith Klugman, MD, an infectious disease specialist at Emory University in Atlanta and moderator of the session at which Pichichero’s study was presented, says that researchers now know of 91 different strains of S. pneumoniae.
The 19A strain is particularly troubling, he says.
"The vaccine took away all of the competing strains, so there’s more of this virulent 19A strain in the body," Klugman tells WebMD.
Klugman notes that Wyeth pharmaceutical company is developing a vaccine that includes strain 19A.
"That should help resolve the problem," he says.
Pichichero tells WebMD that children with recurring ear infections should undergo an ear tap, called tympanocentesis, as that’s the only way to determine if someone has a resistant strain of the bacteria.
He adds that he’s not convinced the vaccine is totally to blame for the emergence of the drug-resistant ear infection. "It could have happened in nature anyway."