Variation in Consumption of Human Milk

摘要: MATERIALS AND METHODSSubjects. Fecal samples were collected from 40 exclusively breast-fed term infants at 3 and 4 months of age (UC Davis Lactation Study). None of the infants enrolled in this study received antibiotic treatment, infant formula, or solid food before the time of sampling. Parents transferred their infant fecal samples into sterile plastic tubes and were instructed to immediately store the samples at J20C until transported by study personnel. Fecal samples were transported to the laboratory on dry ice and stored at J80C before processing. The University of California Davis Institutional Review Board approved all aspects of the study and informed consent was obtained from all subjects. This trial was registered on clinicaltrials. gov (identification number NCT01817127). Microbial isolations. For isolation of Bifidobacterium, 100 mg of each fecal sample was taken aseptically, transferred to a sterile tube, diluted 10-fold with 1% peptone water (Becton, Dickinson, Sparks, MD), and homogenized by vortexing. Ten-fold dilutions were prepared with 1% peptone water and inoculated on modified basal salts medium (BSM) agar (mBSM). Modified BSM agar was prepared by supplementing de Man-Rogosa-Sharpe (MRS) medium (Becton, Dickinson, Sparks, MD) with 15 g/liter agar, 500 mg/liter L-cysteine-HCl, 100 mg/liter mupirocin, 25 mg/liter kanamycin, 4.28 mg/liter polymyxin B, 25 mg/liter iodoacetate, 20 mg/liter nalidixic acid, and 25 mg/ml of 2, 3, 5-triphenyltetrazolium chloride (Sigma, St. Louis, MO). The plates were incubated for 48 h at 37 C in an anaerobic chamber (Coy Laboratory Products, Grass Lake, MI) in an atmosphere …