Comparison of early-onset neonatal sepsis caused by Escherichia coli and group B Streptococcus.

Abstract

The purpose of this study was to compare maternal characteristics and neonatal morbidity and mortality rates that are associated with early-onset neonatal sepsis that is caused by group B Streptococcus and Escherichia coli.
This was a retrospective review of newborn infants with a positive blood culture (and/or cerebrospinal fluid) that was positive for either E coli or group B Streptococcus during the first week of life. Data were abstracted from maternal and neonatal medical records.
Among 28,659 deliveries during the study period, 102 episodes of early-onset neonatal sepsis were identified, 61 of which were caused by group B Streptococcus and 41 of which were caused by E coli. E coli sepsis cases had a lower birth weight, a higher percentage with 5-minute Apgar score <7, and a longer stay in the hospital neonatal intensive care unit and required mechanical ventilation more frequently. Death after early-onset neonatal sepsis with E coli was also more frequent.
Early-onset sepsis with E coli is associated with more morbidity and a higher mortality rate compared with early-onset group B Streptococcus.

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Comparison of early-onset neonatal sepsis caused by
Escherichia coli and group B Streptococcus
Kathleen Mayor-Lynn, MD,aVı ´ctor Hugo Gonza ´lez-Quintero, MD, MPH,a,*
Mary Jo O’Sullivan, MD,aAlan I. Hartstein, MD,b,cSonia Roger, MT,c
Madeline Tamayo, RNc
Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine,aand Department of Medicine,
Division of Infectious Diseases,bUniversity of Miami School of Medicine; and Department of Infection Control,
Jackson Health System, Miami, Flac
Received for publication August 31, 2004; revised October 10, 2004; accepted December 7, 2004
KEY WORDS
Early-onset neonatal
sepsis
Group B
Streptococcus
Escherichia coli
Objective: The purpose of this study was to compare maternal characteristics and neonatal
morbidity and mortality rates that are associated with early-onset neonatal sepsis that is caused
by group B Streptococcus and Escherichia coli.
Study design: This was a retrospective review of newborn infants with a positive blood culture
(and/or cerebrospinal fluid) that was positive for either E coli or group B Streptococcus during the
first week of life. Data were abstracted from maternal and neonatal medical records.
Results: Among 28,659 deliveries during the study period, 102 episodes of early-onset neonatal
sepsis were identified, 61 of which were caused by group B Streptococcus and 41 of which were
caused by E coli. E coli sepsis cases had a lower birth weight, a higher percentage with 5-minute
Apgar score !7, and a longer stay in the hospital neonatal intensive care unit and required
mechanical ventilation more frequently. Death after early-onset neonatal sepsis with E coli was
also more frequent.
Conclusion: Early-onset sepsis with E coli is associated with more morbidity and a higher
mortality rate compared with early-onset group B Streptococcus.
? 2005 Elsevier Inc. All rights reserved.
Among very low birth weight infants, the greatest
lethal risk is extreme prematurity. Early-onset sepsis
(during the first week of life) fortunately is an infrequent
complication, which in the past was most frequently
caused by group B Streptococcus (GBS).
After the development and implementation of con-
sensus guidelines for GBS prophylaxis in 1996,1both the
frequency of and death from early-onset sepsis that is
caused by this bacteria has decreased markedly. The
initial guidelines recommended both a screen and a risk-
based approach for intrapartum antibiotic prophylaxis.
The modified 2002 guidelines recommend universal
screening by vaginal and rectal GBS cultures for all
pregnant women at 35 to 37 weeks of gestation.2In
Presented at the 52nd Annual Clinical Meeting of the American
College of Obstetricians and Gynecologists, Philadelphia, Pa, May 2-5,
2004.
* Reprint requests: Vı´ctor H. Gonza ´ lez-Quintero, MD, MPH,
University of Miami, PO Box 016960 (R-136), Miami, FL 33101.
E-mail: vhgonzalez@med.miami.edu
0002-9378/$ - see front matter ? 2005 Elsevier Inc. All rights reserved.
doi:10.1016/j.ajog.2004.12.031
American Journal of Obstetrics and Gynecology (2005) 192, 1437–9
www.ajog.org

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2003, the overall disease incidence was 0.32, which
represented a 34% decline in incidence since 2000 to
2001.3
Intrapartum antibiotic prophylaxis has been shown
to be most effective to prevent GBS early-onset sepsis,
regardless of which of the aforementioned strategies is
used to prevent this disease. The widespread use of
antibiotics has led to concern over the possible selection
for other organisms and/or increased antibiotic resis-
tance. There is a concern that early-onset sepsis could be
caused by other more virulent organisms in the future.4,5
Although Gram-positive organisms (most commonly
GBS) were responsible most infections between 1991
and 1993, Gram-negative organisms (most commonly
Escherichia coli) became the most frequent cause of
early-onset sepsis between 1998 and 2000.5,6The objec-
tives of this study were to compare maternal character-
istics and neonatal morbidity and mortality rates that
were associated with early-onset neonatal sepsis caused
by E coli and GBS.
Study design
This was a retrospective study of early-onset neonatal
sepsis cases caused by either E coli or GBS at Jackson
Memorial Hospital between January 1, 1998, and June
30, 2002. Approval from the University of Miami’s
Institutional Review Board was obtained. Early-onset
sepsis was defined as a positive blood or cerebrospinal
fluid culture that was obtained between birth and the
end of day 6 of life. Analyzed maternal variables
included demographics, the number of vaginal exami-
nations, the duration of rupture of membranes, the use
of fetal scalp electrodes and/or intrauterine pressure
catheters, the development of chorioamnionitis, and
the gestational age at delivery. Neonatal variables
included birth weight, Apgar scores at 5 minutes,
length of stay, number of days in the neonatal intensive
care unit, and neonatal morbidities (specifically septi-
cemia, pneumonia, intraventricular hemorrhage, sei-
zures, acidosis[pH
!7.20],
mechanical ventilation).
Statistical analyses were performed with SPSS for
Windows (version 10.0; SPSS Inc, Chicago, Ill). De-
scriptive statistics were obtained for all variables.
Continuous variables were analyzed with 2- sample
t-test, and dichotomous variables were analyzed by
chi-squared tests.
and theneedfor
Results
There were 28,659 live births during the study period.
One hundred two cases of early-onset neonatal sepsis
were caused by GBS (61 cases) or E coli (41 cases). No
significant differences were noted with respect to mater-
nal demographics. There was no perceptible increase in
the number of cases of E coli–induced early-onset sepsis
during the era of risk-based GBS prophylaxis. A
comparison of intrapartum factors between cases of
early-onset GBS and E coli sepsis in the neonate is
shown in the Table I.
Of the most common morbidities that are associated
with both E coli and GBS early-onset neonatal sepsis,
only septicemia and mechanical ventilation were signif-
icantly higher in the E coli group (Table II). Most
importantly, the neonatal mortality rate was increased
Table I
Maternal and neonatal variables among cases with early-onset GBS and E coli sepsis
VariableGBS cases (n = 61) E coli cases (n = 41)P value
Vaginal examination (n)*
Duration of rupture of membranes (hr)*
Chorioamnionitis (% affected)
Fetal scalp electrode (% used)
Gestational age at delivery (wk)*
Birth weight (g)
5-Minute Apgar score !7 (%)
Length of stay (d)*
Neonatal intensive care unit (d)*
4.8 G 31
17.5 G 59.6
14.5
16.7
37.0 G 4.7
3151.7 G 1032.5
14.3
18.2 G 24.4
8.8 G 25.4
1.7 G 1.4
1.3 G 5.2
0
9.1
32.6 G 6.2
2055.9 G 1163.3
36.1
43.0 G 53.5
32.0 G 52.9
!.01
.044
.034
NS
!.01
!.01
.04
.014
.021
NS, Not significant.
* Data are given as mean G SD.
Table II
early-onset sepsis caused by E coli and GBS
Selected neonatal morbidities among cases with
Variable
GBS cases
(%)
E coli cases
(%)P value
Septicemia
Pneumonia
Seizure
Acidosis
Intraventricular hemorrhage
Mechanical ventilation
56.7
18.3
3.4
30.5
3.4
13.6
85.3
9.1
21.9
30.5
12.5
53.1
!.01
NS
NS
NS
NS
!.0001
NS, Not significant.
1438Mayor-Lynn et al

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among neonates who were diagnosed with E coli sepsis
compared with GBS sepsis (19% vs 7%; P ! .007).
Comment
Early-onset sepsis is a rare, but potentially lethal
problem, that affects primarily neonates of low birth
weight.1Vertical transmission of GBS during labor or
delivery may result in an invasive infection in the
newborn infant during the first week of life, which
results in approximately 1600 cases and 80 deaths
annually, according to the latest report from the Centers
for Disease Control.3The incidence of invasive GBS
infections among pregnant women in the United States
decreased by 21% from 1993 to 1998 to an incidence of
0.23 per 1000 live births,7with a further decrease in
2003.3The emergence of other pathogens and an
increase in the incidence of early-onset sepsis caused
by E coli during or after this interval have been
reported.4However, we found no increase in the number
of cases of early-onset E coli sepsis at our institution.
There were a number of differences that were noted
between cases of E coli– and GBS-induced early-onset
sepsis, which were related mostly to intrapartum events
in the GBS cases. Infants who received a diagnosis of
E coli sepsis were born at an earlier gestational age and
of lower birth weights and had a higher percentage of
Apgar scores of !7 at 5 minutes than those with GBS
sepsis. It follows then that these infants had a longer
length of stay and a greater number of days spent in the
neonatal intensive care unit. The 2 morbidities that were
significantly higher in the E coli group were septicemia
and a need for mechanical ventilation. More impor-
tantly, the neonatal mortality rate was significantly
higher with E coli sepsis, compared with GBS sepsis.
The increased mortality rate in the E coli sepsis group
may be confounded by the higher prematurity rate
among the affected neonates in our study group.
In conclusion, E coli sepsis occurred in a more
premature patient population in comparison to GBS
and was associated with higher morbidity and mortality
rates. On-going surveillance of infecting organisms and
antimicrobial prophylaxis that is directed at GBS must
continue.
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