Table 4. Studies with characterization of bacteria present in breast milk by microbiota profiling.

Predominant taxa	Characterization method	Abundance of bifidobacteria and lactobacilli	N	Population	Collection protocol	Reference
Staphylococcus sp., Streptococcus sp.	Pyrosequencing	“very few sequences”	16	US	Cleansing with iodine	[18]
					Entire breast
Leuconostoc sp. Weisella sp.	Pyrosequencing	No Bifidobacterium or Lactobacillus reported	18	Finnish	Cleansing with iodine	[15]
					Rejection of first drops
Staphylococcus sp., Pseudomonas sp., Streptococcus sp.,	Pyrosequencing	Bifidobacterium 1.3% Lactobacillus absent	7	Swiss	Cleansing with aseptic soap	[8]
					Rejection of foremilk
Staphylococcaceae, Streptococcaceae, Pseudomonadaceae	Pyrosequencing	No Bifidobacterium or Lactobacillus reported	10	Spanish	Cleansing with chlorhexidine	[36]
					Rejection of first drops
Acinetobacter sp., Staphylococcus sp.	Ion Torrent	Bifidobacterium 2% Lactobacillus 1.6%	8	US	Cleansing with saline	[19]
					First 10 to 15 ml taken
Staphylococcus sp., Unclassified genus of Enterobacteriaceae, Pseudomonas sp., Streptococcus sp.,	Illumina	Bifidobacterium 0.8% Lactobacillus 3%	39	USA Caucasian	Cleansing with saline	[37]
					First 5 to 15 ml taken
Staphylococcus sp., Pseudomonas sp.,	Metagenomics	No Bifidobacterium Lactobacillus 0.2%	10	US	None	[21]
Staphylococcus sp., Pseudomonas sp.,	Metagenomics	Bifidobacterium 0.1% Lactobacillus 0.6%	10	Spanish	Cleansing with chlorhexidine	[20]
					Rejection of first drops