Fwd: [S-A] Human Milk and the Prevention of Infection

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" Misty L. Trepke "

Mon, 18 Aug 2003 09:23:22 -0000

[s-A] Human Milk and the Prevention of Infection

 

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Misty L. Trepke

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Human Milk and the Prevention of Infection

Benjamin Estrada, MD

 

Breast-feeding is the recommended form of infant nutrition. In

addition to nutritional and psychological benefits, it is well known

that breast-feeding has a protective effect against infection. Human

milk contains significant concentrations of secretory IgA and

oligosaccharides, which provide protection against bacterial

infection. In addition, the bifidus factor present in human

milk stimulates the development of protective intestinal microflora

in breast-fed infants. Protective effects of human milk against

infection caused by rotavirus, enterobacteria, and Streptococcus

pneumoniae are well known.

 

The following are a series of recent findings that add significant

information to our understanding of the anti-infective properties of

human milk. Recently, the presence of different natural

antibacterial agents has been described in human milk. Hakansson and

collaborators (Hakansson A et al. Mol Microbiol. 2000;35:589-600)

have reported that alpha-lactalbumin present in human milk has

bactericidal activity against S pneumoniae. The antibacterial

activity of this substance seems to be independent of S pneumoniae

bacterial serotype or antibiotic resistance pattern. In addition,

Liepke and collaborators (Liepke C et al. J Chromatogr B Biomed Sci

Appl. 2001;752:369-377) have identified a peptide in human milk

similar to a proteolytic fragment of human k-casein. This peptide

was found to inhibit the growth of gram-positive and gram-negative

bacteria as well as yeasts (Hakansson A et al. Mol Microbiol.

2000;35:589-600). Human milk contains relatively large amounts of

xanthine oxidase, and this enzyme has been linked to antibacterial

activity. The combination of xanthine oxidase and nitrites present

in the newborn's GI tract generates nitric oxide, which inhibits the

metabolism of Enterobacteriaceae, Escherichia coli, and Salmonella

enteritidis (Hancock JT et al. Antimicrob Agents Chemother.

2002;46:3308-3310).

 

It has been proved that human milk contains protective cytokines,

such as granulocyte colony-stimulating factor (G-CSF). The

concentrations of this cytokine have been found to be higher during

the first 2 postpartum days, and they are lower in breast milk of

mothers who have given birth to premature infants than in milk of

mothers who have given birth to full-term infants. In addition, G-

CSF receptors are present in intestinal cells of breast-fed

infants (Calhoun DA et al. Pediatrics. 2000;105:e7).

 

Among the major protective factors present in human milk are

secretory IgA and sialic acid, which have activity against

infections with enteric pathogens. Recently, investigators have

demonstrated that these factors present in human milk survive

passage through the GI tract and are present in higher

concentrations in the stool of breast-fed infants than in the stool

of bottle-fed infants (Kohler H et al. J Pediatr Gastroenterol Nutr.

2002;34:188-193; Fernandes RC et al. Diagn Microbiol Infect Dis.

2002;44:331-336).

 

Two recent studies support previous research that suggested a role of

breast-feeding in protecting against infection caused by rotavirus.

In a study performed in Italy, breast-feeding was found to be

associated with a significantly lower rate of nosocomial rotavirus

infection. Breast-feeding was more effective than administration of

lactobacillus GG in the prevention of nosocomial rotavirus infection

in the same setting (Mastretta E et al. J Pediatr Gastroenterol

Nutr. 2002;35:527-531; Gianino P et al. J Hosp Infect. 2002;50:13-

17).

 

New data suggest that the anti-infective properties of human milk

can be preserved for up to 3 months after its expression when the

milk is frozen at 2200C (24.00F) (Ogundele MO. Br J Biomed Sci.

2002;59:205-211).

 

These findings should encourage the promotion and acceptance of

breast-feeding as the ideal form of infant nutrition. Time spent in

the promotion of breast-feeding is always time well invested.

 

 

Dr Estrada is associate professor of pediatrics, division of

infectious diseases, University of South Alabama, Mobile.

 

Infect Med 20(6):270, 2003. ) 2003 Cliggott Publishing, Division of

SCP Communications