Staphylococcus epidermidis: a differential trait of the fecal microbiota of breast-fed infants.
BACKGROUND
Breast milk is an important source of staphylococci and other bacterial groups to the infant gut. The objective of this work was to analyse the bacterial diversity in feces of breast-fed infants and to compare it with that of formula-fed ones. A total of 23 women and their respective infants (16 breast-fed and 7 formula-fed) participated in the study. The 16 women and their infants provided a sample of breast milk and feces, respectively, at days 7, 14, and 35. The samples were plated onto different culture media. Staphylococcal and enterococcal isolates were submitted to genetic profiling and to a characterization scheme, including detection of potential virulence traits and sensitivity to antibiotics.


RESULTS
The feeding practice had a significant effect on bacterial counts. A total of 1,210 isolates (489 from milk, 531 from breast-fed and 190 from formula-fed infants) were identified. Staphylococcus epidermidis was the predominant species in milk and feces of breast-fed infants while it was less prevalent in those of formula fed-infants. Enterococcus faecalis was the second predominant bacterial species among the fecal samples provided by the breast-fed infants but it was also present in all the samples from the formula-fed ones. The biofilm-related icaD gene and the mecA gene were only detected in a low number of the S. epidermidis strains. Several enterococcal isolates were also characterized and none of them contained the cylA or the vanABDEG antibiotic-resistance genes. All were sensitive to vancomycin.


CONCLUSIONS
The presence of S. epidermidis is a differential trait of the fecal microbiota of breast-fed infants. Globally, the staphyloccal isolates obtained from milk and feces of breast-fed infants contain a low number of virulence determinants and are sensitive to most of the antibiotics tested.
Jiménez
Esther
E
Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Universidad Complutense de Madrid, 28040, Madrid, Spain. esjimene@vet.ucm.es
Delgado
Susana
S
Maldonado
Antonio
A
Arroyo
Rebeca
R
Albújar
Mar
M
García
Natalia
N
Jariod
Manel
M
Fernández
Leonides
L
Gómez
Adolfo
A
Rodríguez
Juan M
JM
D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001942:Breast Feeding; D015169:Colony Count, Microbial; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D005243:Feces / Q000382:microbiology*; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D041943:Infant Formula; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D008895:Milk, Human / Q000382:microbiology*; D019105:Random Amplified Polymorphic DNA Technique; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D014774:Virulence
D000900:Anti-Bacterial Agents
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