News du jour	Ob.Gyn.News April 15, 1998
ACDM	Intrapartum Administration of Ampicilln Prophylaxis in GBS Mothers May Raise Risk of Neonatal E. coli Infection

Increase seen in serious cases of the disease.

BY ELIZABETH MECHCATIE

Despite aggressive treatment, six babies died of fulminant early-onset E. coli infection during the entire study period; all six had ampicillin-resistant organisms, and the mothers of four had received intrapartlim ampicillin.

The widespread use of intrapartum ampicillin in women who are carriers of group B streptococci may be creating a serious problem: an increase in severe cases of early onset Escherichia coli disease in newborns caused by resistant organisms, Chicago researchers say.

"We have shown a shift of neonatal early-onset E.coli infections from less fulminant disease associated with ampicillin sensitive strains to more fulminant disease associated with amipicillin-resistant strains," reported Dr. Tessy Joseph of Cook County Children's Hospital and her associates (Arch. Pediatr. Adolesc. Med. 152[l]:35-40, 1998).

When the Centers for Disease Control and Prevention's guidelines on group B Streptococci prophylaxis were being develeoped, there was a concern that antibiotic prophylaxis would alter the types of pathogens seen in early onset sepsis and that resistance of pathogens to antibiotics could occur.

In an interview, Dr. Sharon Phelan, vice chairwoman of the American College of Obstetrcians and Gynecologists' Cornmittee on Obstetric Practice, said that the study's results make it clear that ampicillin resistance "is an entity we need to be aware of."

Nevertheless, it remains unclear whether ampicillin prophylaxis for group B streptococci(GBS) is to blame for the findings in this study, she said, noting that the drug is "used like water across the country" for various adult infections. Another possibility is that the efficacy of intrapartum ampicillin in eradicating GBS disease and reducing related neonatal fatalities enables other infections to emerge, Dr. Phelan said.

There is also "a lot of confusion and abuse of the two [CDC-endorsed prophylaxis] strategies," Dr. Phelan added. Some physicians are culturing women near the end of pregnancy and are immediately treating those with positive results instead of waiting until the woman is in labor; in some cases, this process is repeated before delivery, she said.

Whatever the cause, physicians need to realize that the risk of resistant strains is not just a theoretical concern. . . . This shows it is a real phenomenon," said Dr. Phelan of the University of Alabama, Birmingham.

The investigators decided to do their study after noticing an increase in the number of low-birth-weight babies delivered at Cook County Hospital who developed early-onset E. coli disease after chemoprophylaxis for GBS disease was implemented.

Their study compared infection and fatality rates between 1982 and 1987 and between 1988 and 1993 when the use of intrapartum ampicillin increased.

During the later time period, the incidence of early-onset CBS infections dropped in babies with birth weights below 1,500 g, which was attributed to chemoprophylaxis. There was a "steady shift" of early-onset GBS infections "from small neonates with high fatality rates to larger neonates with lower fatality rates."

Over both periods, 30 neonates were diagnosed with E. coli infections; the neonates had a positive blood culture and symptoms in the first week of life. The infection rate during the first period was 0.37 per 1,000 births and 0.62 per 1,000 during the second period. This increase, which was not significant, was due to an increase in infections in babies with birth weights between 1501 g and 2500 g.

During the first period, 3 of the 12 cases diagnosed were caused by ampicillin resistant E. coli, versus 12 of the 18 cases diagnosed in the second period, a significant increase. During the second period, 61 % of the mothers of infected babies had received intrapartum ampicillin versus 17% in the first period.

Despite aggressive treatment, six babies died of fulminant early-onset E. coli infection during the entire study period; all six had ampicillin-resistant organisms, and the mothers of four had received intrapartlim ampicillin.