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Potential consequences of widespread antepartal use of ampicillin
C V Towers1, M H Carr, G Padilla
1University of California, Irvine, USA.
Insights
Antenatal ampicillin use in mothers increased neonatal sepsis caused by ampicillin-resistant bacteria. Penicillin G is now recommended for group B streptococci prophylaxis.
Area of Science:
- Obstetrics and Gynecology
- Neonatal Medicine
- Infectious Diseases
Background:
- Antenatal antibiotic use has risen, particularly ampicillin for group B streptococci (GBS) prophylaxis.
- Concerns exist regarding the impact of antenatal antibiotics on neonatal sepsis resistance patterns.
Purpose of the Study:
- To investigate the association between antenatal ampicillin and the incidence of early-onset neonatal sepsis caused by non-GBS organisms.
- To assess the ampicillin resistance patterns in neonatal sepsis isolates following antenatal ampicillin exposure.
Main Methods:
- Prospective cohort study (1991-1996) analyzing 42 cases of early-onset neonatal sepsis.
- Data collected included bacterial type, drug resistance, antenatal antibiotic use, and gestational age.
- Early-onset neonatal sepsis defined as onset within 7 days of birth.
Main Results:
- Ampicillin-resistant non-GBS neonatal sepsis was significantly higher in neonates whose mothers received antenatal ampicillin (87% vs. 17%).
- Overall antenatal antibiotic use increased from <10% to 16.9% during the study period.
- Incidence of GBS sepsis decreased, while non-GBS sepsis, particularly E. coli, increased.
Conclusions:
- Increased antenatal ampicillin administration may contribute to ampicillin-resistant non-GBS neonatal sepsis.
- Penicillin G is recommended over ampicillin for GBS prophylaxis.
- Alternative strategies like immunotherapy or vaginal washing warrant further investigation.
Objective:
Recommendations for the use of antenatal antibiotics in obstetrics have increased in the past few years, especially for prophylaxis against group B streptococci, for prolongation of the latency time in patients with preterm premature rupture of the membranes, and as an adjuvant treatment in preterm labor. Our objective was to determine whether the use of antenatal ampicillin affects the incidence of and resistance of early-onset neonatal sepsis with organisms other than group B streptococci.
Study Design:
A prospective cohort study was performed between January 1, 1991, and December 31, 1996. Every case of blood culture-proven neonatal sepsis was prospectively surveyed. The type of bacteria isolated, drug resistance, antenatal antibiotic use and treatment indication, gestational age at delivery, and other antenatal and outcome variables were gathered. Early-onset neonatal sepsis was defined as disease onset within 7 days after birth.
Results:
A total of 42 cases of early-onset neonatal sepsis among 29,897 neonates delivered were found during the 6-year period. Of these, 15 cases were due to group B streptococci and 27 were the result of non-group B streptococcal organisms (21 gram-negative rods and 6 gram-positive cocci). Among the 27 non-group B streptococcal cases, 15 mothers had received antenatal ampicillin and 13 of the 15 bacterial isolates from these neonates (87%) were resistant to ampicillin, versus only 2 ampicillin-resistant isolates (17%) among the 12 cases in which no antenatal antibiotics were administered (P = .0004). Of the 15 mothers who were treated with ampicillin, 13 received more than 1 dose. In evaluating each year of the study, the overall administration of antibiotics to pregnant women in the antenatal period increased from <10% in 1991 to 16.9% in 1996. The incidence of early-onset neonatal sepsis with group B streptococci decreased during this time, whereas the incidence of early-onset sepsis with non-group B streptococcal organisms, especially Escherichia coli, increased.
Conclusions:
The increased administration of antenatal ampicillin to pregnant women may be responsible for the increased incidence of early-onset neonatal sepsis with non-group B streptococcal organisms that are resistant to ampicillin. At this time penicillin G, rather than ampicillin, is therefore recommended for prophylaxis against group B streptococci. In addition, future studies are needed to determine whether alternate approaches, such as immunotherapy or vaginal washing, could be of benefit.