Risk factors associated with ampicillin-resistant infection in newborns in the era of group B streptococcal prophylaxis.
OBJECTIVE
To document the trend of ampicillin-resistant infections in newborns weighing at least 1500 g and to determine factors associated with ampicillin-resistant neonatal early-onset infection in the era of routine group B streptococcal prophylaxis.


METHODS
Case-control study.


METHODS
Referral hospital with level I through level III nurseries.Patients Newborns aged 0 to 7 days with cultures positive for bacterial infection, born from January 1994 to August 2002 (n = 53). Random controls were matched to admission year and nursery level (n = 159).


METHODS
Trends of and factors associated with ampicillin-resistant infections.


RESULTS
Trends in our institution were the same as those found in some recent reports, a decrease in group B streptococcal early-onset infections without a concomitant increase in gram-negative early-onset infections. Specifically, when stratified by birth weight, newborns weighing at least 1500 g had no increase in gram-negative pathogens in the eras both before and after group B streptococcal prophylaxis (0.8 per 1000 live births to 0.3 per 1000 live births; incidence ratio, 2.3 [95% confidence interval, 0.5-10.9]). No increase in ampicillin resistance was seen during the same 3 periods (50%, 60%, and 50%, respectively; P =.97). Independent risk factors associated with ampicillin-resistant early-onset infection were intrapartum antibiotics for a 24-hour duration or longer (odds ratio, 4.8 [95% confidence interval, 1.0-23.3]) and clinical chorioamnionitis (odds ratio, 9.2 [95% confidence interval, 2.6-32.9]).


CONCLUSIONS
No increase in early-onset infections with gram-negative or ampicillin-resistant pathogens was detected. Ampicillin-resistant early-onset infection was associated with intrapartum antibiotics given for 24 hours or longer prior to delivery and with clinical chorioamnionitis. Ampicillin sodium and gentamicin sulfate remain appropriate initial antibiotic therapies for early-onset infection in newborns weighing at least 1500 g and without these risk factors.
Rentz
Alison C
AC
Department of Pediatrics, Divisions of Neonatology, University of Utah School of Medicine, Salt Lake City 84132, USA. alison.rentz@hsc.utah.edu
Samore
Matthew H
MH
Stoddard
Gregory J
GJ
Faix
Roger G
RG
Byington
Carrie L
CL
D000668:Ampicillin Resistance; D001724:Birth Weight; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology* / Q000517:prevention & control; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D007744:Obstetric Labor Complications / Q000188:drug therapy / Q000453:epidemiology; D011247:Pregnancy; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D013290:Streptococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000517:prevention & control; D013292:Streptococcus agalactiae; D014589:Utah / Q000453:epidemiology