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Bacterial infections in infants 60 days and younger: epidemiology, resistance, and implications for treatment
1Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Children's National Medical Center, Washington, DC, USA.
Insights
Ampicillin resistance is high in gram-negative rods (GNRs) causing invasive bacterial infections in infants. Initial antibiotic therapy for infants 60 days or younger in the emergency department (ED) should consider alternatives to ampicillin, such as third-generation cephalosporins.
Area of Science:
- Pediatrics
- Infectious Diseases
- Pharmacology
Background:
- Invasive bacterial infections pose a significant risk to infants 60 days or younger.
- Optimal empiric antibiotic selection is crucial for effective treatment in this vulnerable population.
- Emergency departments (EDs) frequently manage infants with suspected bacterial infections.
Purpose of the Study:
- To determine optimal initial antibiotic therapy for suspected invasive bacterial infections in infants 60 days or younger.
- To analyze pathogen frequency and antibiotic resistance patterns in this age group.
- To guide empiric antibiotic selection in the ED setting.
Main Methods:
- Retrospective case series of positive blood, urine, and cerebrospinal fluid cultures in children 60 days or younger (1994-1997).
- Identification and frequency analysis of bacterial pathogens.
- Subgroup analysis of antibiotic resistance patterns among gram-negative rods (GNRs) in ED patients.
Main Results:
- Gram-negative rods (GNRs) were the most common pathogens (79.3%) isolated from ED patients.
- Over 60% of GNRs isolated from ED patients exhibited ampicillin resistance.
- No Listeria isolates were identified during the study period.
- All GNR isolates were sensitive to gentamicin sulfate and cefotaxime sodium.
Conclusions:
- Ampicillin may not be necessary or beneficial as empiric therapy for infants 60 days or younger in the ED, given high GNR resistance.
- Third-generation cephalosporins, with or without gentamicin, are suggested as alternative empiric initial antibiotic therapy.
- These findings are relevant for centers with similar low Listeria incidence and high GNR ampicillin resistance.
Objective:
To establish what might be more optimal initial antibiotic therapy for suspected invasive bacterial infections in infants 60 days or younger who are evaluated in the emergency department (ED).
Setting:
Urban university-affiliated pediatric referral center with an average yearly ED census of 52000 visits during the study period.
Design And Methods:
We assembled a retrospective case series of all positive blood, urine, and cerebrospinal fluid cultures in children 60 days or younger from January 1, 1994, through December 31, 1997, obtained from both inpatients and patients initially evaluated in the ED. From this case series we determined the frequency of bacterial pathogens responsible for such infections in this age group. Pathogens were defined as group B streptococcus, various enteric gram-negative rods (GNRs), Listeria monocytogenes, enterococcus, Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type B, and Staphylococcus aureus. A subgroup analysis was performed to determine resistance patterns among the GNRs isolated from patients evaluated in the ED.
Results:
A total of 367 pathogens were isolated: 187 (51.0%) in the neonatal intensive care unit, 153 (41.7%) in the ED, 20 (5.4%) in the inpatient wards, and 7 (1.9%) in the pediatric intensive care unit. Of the 121 pathogens isolated from 120 ED patients that were eligible for review, 94 (77.7%) were in the urine only, 16 (13.2%) in blood only, 4 (3.3%) in cerebrospinal fluid only, 3 (2.5%) in blood and cerebrospinal fluid, and 4 (3.3%) in blood and urine. Organisms isolated included GNRs (n = 96, 79.3%), group B streptococcus (n = 14, 11.6%), enterococcus (n = 7, 5.8%), S. pneumoniae (n = 3, 2.5%), and N. meningitidis (n = 1, 0.8%). No Listeria were isolated. Of the 96 GNRs isolated, 60 (62.5%; 95% confidence interval, 52.8%-72.1%) were ampicillin resistant. All were sensitive to gentamicin sulfate and cefotaxime sodium.
Conclusions:
Our results reveal 2 important facts: (1) during a 4-year period, no isolates of Listeria were identified from any patients 60 days or younger; and (2) of the 96 GNRs isolated from patients in the ED, more than 60% were ampicillin resistant. These data suggest that in similar centers with a low incidence of infection with Listeria and high levels of ampicillin resistance among GNRs, empiric use of ampicillin as part of a combination for presumed bacterial infections in patients 60 days or younger initially evaluated in the ED may be neither necessary nor beneficial. Consideration should be given to empiric initial antibiotic therapy using a third-generation cephalosporin with or without gentamicin.