Late-onset Bloodstream Infections in Hospitalized Infants

In This Article

Abstract and Introduction

Abstract

Background: The epidemiology and incidence of late-onset blood stream infections (BSIs) in premature infants have been described, but studies describing late-onset BSI in term infants are sparse. We sought to describe the pathogens, incidence, risk factors and mortality of late-onset BSI in hospitalized term infants.

Methods: A cohort study was conducted of infants ≥37 weeks gestational age and ≤120 days of age discharged from Pediatrix Medical Group neonatal intensive care units from 1997 to 2010. We examined all cultures obtained from day of life 4–120 and used multivariable regression to assess risk factors for late-onset BSI.

Results: We found a total of 206,019 infants cared for between day of life 4 and 120, and the incidence of late-onset BSI was 2.7/1000 admissions. We identified Gram-positive organisms in 64% of the cultures and Gram-negative organisms in 26%. We found a decreased risk of late-onset BSI in infants with the following characteristics: small for gestational age, delivery by Cesarean, antenatal antibiotic use and discharged in the later years of the study. Late-onset BSI increased the risk of death after controlling for confounders [odds ratio 8.43 (95% confidence interval 4.42–16.07)].

Conclusion: Our data highlight the importance of late-onset BSI in hospitalized term infants. We identified Gram-positive organisms as the most common pathogen, and late-onset BSI was an independent risk factor for death.

Introduction

Although the incidence of blood stream infections (BSI) in term infants is relatively low, BSI-related mortality and morbidity are high.^[1,2] The epidemiology and incidence of late-onset BSIs in premature infants have been described, but studies describing late-onset BSI in term infants are sparse.^[3,4] Late-onset BSIs in premature infants are most often caused by coagulase-negative staphylococci (CoNS).^[5–7] Group B Streptococcus is the leading cause of early-onset BSI in term infants despite the implementation of intrapartum antibiotic prophylaxis.^[5]

Considering that a high proportion of infants admitted to the neonatal intensive care unit (NICU) are term infants, the need for recent data describing the epidemiology of late-onset BSI in this population is dire.^[8] We evaluated pathogen distribution, incidence, risk factors and mortality of late-onset BSIs in term infants using contemporary data from a large cohort of hospitalized infants.

Table 1. Demographics, N (%)
	No Late-onset BSI (n = 205,485)	Late-onset BSI (n = 534)
GA (weeks)
37	42,953 (21)	110 (21)
38	51,415 (25)	155 (29)
39	50,857 (25)	120 (22)
40	44,441 (22)	117 (22)
41	13,789 (7)	22 (4)
≥42	2030 (1)	10 (2)
Male	120,521 (59)	331 (62)
Race/ethnicity
White	96,029 (49)	187 (38)
Black	29,265 (15)	80 (16)
Hispanic	57,407 (30)	200 (40)
Other	11,413 (6)	29 (6)
Small for GA	22,539 (11)	74 (14)
Apgar score at 5 minutes
0–3	2817 (1)	19 (4)
4–6	10,878 (5)	36 (8)
7–10	185,436 (93)	414 (88)
Cesarean delivery	90,937 (45)	215 (42)
Antenatal antibiotics	49,699 (24)	83 (16)
Early-onset BSI	2055 (1)	11 (2)

Table 2. Incidence and Mortality of Late-onset Bloodstream Infection
Organism	Episodes, n (%)	Episodes/1000 NICU Admissions	Mortality (%)
Gram-positive organisms	354 (64)	1.7	3.8
GPC (unspecified)	153 (28)	0.7	3.0
Coagulase-negative staphylococci	71 (13)	0.3	4.6
Staphylococcus aureus	70 (13)	0.3	4.6
Group B Streptococcus	31 (6)	0.2	6.7
Enterococcus sp.	27 (5)	0.1	0
Gram-negative organisms	145 (26)	0.7	3.9
E. coli	76 (14)	0.4	2.8
Klebsiella sp.	17 (3)	0.1	0
GNR (unspecified)	16 (3)	0.1	9.1
Enterobacter sp.	14 (3)	0.1	0
Pseudomonas sp.	6 (1)	0.03	16.7
Serratia sp.	5 (1)	0.02	0
Yeast	28 (5)	0.1	13.0
Other	25 (5)	0.1	0
Total	552	2.7	4.1

GPC, Gram-positive cocci; GNR, Gram-negative rods.

Table 3. Risk Factors Associated With Late-onset Bloodstream Infection
	Adjusted HR (95% CI)	P
Gestational age (weeks)
37	Reference	—
38	1.25 (0.96–1.62)	0.10
39	1.10 (0.83–1.46)	0.50
40	1.18 (0.88–1.57)	0.27
41	0.61 (0.36–1.02)	0.06
≥42	0.59 (0.22–1.62)	0.31
Male	1.02 (0.85–1.23)	0.82
Race/ethnicity
White	Reference	—
Black	1.40 (1.07–1.83)	0.01
Hispanic	1.15 (0.93–1.42)	0.19
Other	0.95 (0.62–1.46)	0.82
Small for GA	0.66 (0.50–0.86)	0.002
Apgar score at 5 minutes
7–10	Reference	—
4–6	0.86 (0.61–1.21)	0.39
1–3	0.72 (0.46–1.14)	0.17
Cesarean delivery	0.77 (0.64–0.93)	0.007
Antenatal antibiotics	0.71 (0.55–0.92)	0.009
Early-onset BSI	0.64 (0.36–1.14)	0.13
Discharge year	0.96 (0.93–0.98)	<0.001