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Table 1 Baseline Characteristics of Paired Infant Samples (n = 210)

From: The infant gut resistome is associated with E. coli and early-life exposures

Infant Characteristics
Infant Sex (%)
 Female 89 (42.4)
 Male 121 (57.6)
Infant Race (%)  
 White 197 (93.8)
 Other 13 (6.2)
Feeding Mode at 6-Week Sample (%)  
 Breast fed 157 (74.8)
 Formula fed 7 (3.3)
 Combination 46 (21.9)
Feeding Mode at 1-Year Sample (%)  
 Breastfed 70 (33.3)
 Formula fed 7 (3.3)
 Combination 133 (63.3)
Antibiotics During Initial Hospitalization (%)  
 No 203 (96.7)
 Yes 7 (3.3)
Gestational Age at Birth in Weeks [Mean (SD)] 39.05 (1.56)
Birth Weight in Grams [Mean (SD)] 3414 (507)
Age at 6-Week Sample Collection in Days [Mean (SD)] 46.78 (18.44)
Age at 1-Year Sample Collection in Days [Mean (SD)] 375.32 (35.69)
Maternal Characteristics
Delivery Mode (%)
 Vaginal 152 (72.4)
 Cesarean section 58 (27.6)
Prenatal Antibiotics Prior to Delivery (%)  
 No 157 (74.8)
 Yes 39 (18.6)
 Missing 14 (6.7)
Group B Streptococcus Positive (%)  
 No 137 (65.2)
 Yes 68 (32.4)
 Missing 5 (2.4)
Parity (%)*  
 Nulliparous 104 (49.8)
 One 72 (34.4)
 At least two 33 (15.8)
Intrapartum Antibiotic Exposure Class** (%)  
 None 95 (45.2)
 Penicillin 43 (20.5)
 Cephalosporin 43 (20.5)
 Multiple 25 (11.9)
 Other 4 (1.9)
  1. *One mother was missing parity status
  2. **Infants were grouped according to intrapartum antibiotic exposures using the following categories: no antibiotics; penicillin-like antibiotics only (amoxicillins, penicillins); cephalosporins only (cefazolin, cephalexin); multi-drug classes (two or more antibiotics characterized as penicillin, cephalosporin, vancomycin, clindamycin, and/or gentamicin); or “other” antibiotics such as aminoglycosides, glycopeptides, or lincomycin