A rare, antibiotic-resistant form of Group B Streptococcus appears to be getting more common in Minnesota and there's concern that the infection will gain a foothold in the state and sicken more infants.
Group B Strep, or GBS, is a major cause of invasive bacterial disease in babies in the first months of life. If a pregnant woman has the bacteria prior to giving birth she can pass the organism to her baby during its journey through the birth canal. An infant who ingests or inhales the bacteria is at risk of develop a life-threatening illness such as pneumonia, meningitis or a blood infection.
In the United States, previous studies have shown that three types of Group B Strep cause the most disease among babies. But a new study conducted in Minnesota has found the recent emergence of a lesser-known form of GBS, referred to as serotype IV.
"This was rather astounding to us that we had an increase (in serotype IV cases)," said Dr. Patricia Ferrieri, lead author of the study. "I hope that we don't see a trend here."
Ferrieri, a University of Minnesota Medical School physician and researcher, says Group B Strep disease in Minnesota linked to serotype IV accounted for 16 percent of disease cases in 2010 in infants up to six days old. The number of cases was nearly as many as occurred during the previous 10 years combined.
It's not know what caused the uptick in disease caused by serotype IV, but Group B Strep bacteria are a normal part of the common bacteria found in the human digestive tract. However the organisms can become dangerous if they overpopulate the gut and move in to a woman's reproductive tract.
GBS is enough of a concern that physicians routinely screen pregnant women for it toward the end of their pregnancies. Mothers who test positive are given IV antibiotics during labor and delivery to prevent transmission to their infants. But Ferrieri said it's not routine practice to figure out exactly what type of Group B Strep a mother has acquired or whether it's antibiotic resistant.
Her study found that 80 percent of Minnesota's serotype IV cases in 2010 were resistant to the antibiotic clindamycin, one of the drugs used when pregnant women are allergic to penicillin.
"It points out the handicap, deficiency of using a drug for prevention of disease if one hasn't tested the organism in the lab in a test tube to see whether it's susceptible to clindamycin," says Ferrieri.
In the absence of detailed serotype testing for Group B Strep, Ferrieri says physicians should be vigilant in watching for any signs that a newborn is not behaving quite right following birth. She said that could indicate that the mother had an antibiotic-resistant case of GBS and received the wrong drugs.
Her advice for mothers is to be equally vigilant from the moment they arrive at the hospital in labor.
"Know your status, that you are positive or negative," said Ferrieri. "The first question you ask (your health care providers) is 'When are you starting the IV to give me the antibiotic that will prevent my baby from getting Group B Strep infection?'"
Ferrieri's study is published in the April issue of the Center for Disease Control and Prevention's peer-reviewed public health journal "Emerging Infectious Diseases."