Does breast milk protect against septicaemia in the newborn?

Increased risk of group B streptococcal sepsis and meningitis in HIV-exposed uninfected infants in a high-income country

The purpose of this study is to compare group B Streptococcus (GBS) infection incidence in HIV-exposed uninfected (HEU) and HIV-unexposed (HU) infants in a Spanish cohort. We conducted a retrospective study in 5 hospitals in Madrid (Spain). Infants ≤ 90 days of life with a GBS infection were included from January 2008 to December 2017. Incidence of GBS infection in HEU and HU children was compared. HEU infants presented a sevenfold greater risk of GBS infection and a 29-fold greater risk of GBS meningitis compared to HU, with statistical significance. Early-onset infection was tenfold more frequent in HEU children, with statistical significance, and late-onset infection was almost fivefold more frequent in the HUE infants' group, without statistical significance.

CONCLUSION

HEU infants presented an increased risk of GBS sepsis and meningitis. One in each 500 HEU infants of our cohort had a central nervous system infection and 1 in each 200, a GBS infection. Although etiological causes are not well understood, this should be taken into account by physicians when attending this population.

WHAT IS KNOWN

• HIV-exposed uninfected infants are at higher risk of severe infections. • An increased susceptibility of these infants to group B Streptococcus infections has been described in low- and high-income countries, including a higher risk of meningitis in a South African cohort.

WHAT IS NEW

• Group B Streptococcal meningitis is more frequent in HIV-exposed uninfected infants also in high-income countries. • Physicians should be aware of this increased risk when attending these infants.

Relationship between Breastfeeding, Birth History, and Acute Pyelonephritis in Infants

BACKGROUND

Although the clinical importance of the immunological benefits of breastfeeding has been emphasized for decades, their direct relationship with acute pyelonephritis (APN) is still not clear. Our goal was to determine whether breastfeeding truly provides protection against APNs, while investigating the effects of other factors such as sex, age, mode of delivery, and birth weight on APN.

METHODS

A total of 62 infants under 6 months of age who had both microbiologically and radiologically-confirmed APN were enrolled in the case group. Healthy infants (n = 178) who visited the hospital for scheduled vaccinations were enrolled in the control group. The following participant characteristics were compared between the case and control groups: age, sex, birth order among siblings, feeding methods, weight percentile by month, birth weight percentile by gestational age, gestational age at birth, and mode of delivery.

RESULTS

Babies exclusively fed with manufactured infant formulae before 6 months of age had significantly higher risk for APN than breastfed or mixed-fed infants (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.687-7.031; P = 0.001). Firstborn babies had lower risk for APN than 2nd- or 3rd-born babies (OR, 0.43; 95% CI, 0.210-0.919). Other factors that increased the risk for APN were low birth weight percentiles (OR, 8.33; 95% CI, 2.300-30.166) and birth via caesarean section (OR, 2.32; 95% CI, 1.097-4.887). There were more preterm births in the case group (10.9% vs. 1.7%; P = 0.002), but this did not increase the risk for APN (OR, 4.47; P = 0.063).

CONCLUSION

Feeding exclusively with formula before 6 months of age was related to higher risk for APN, which demonstrates that breastfeeding has a protective effect against APN. The other risk factors for APN were birth order (≥ 2nd-born), low birth weight, and birth via caesarean section.

Considerations in the pharmacologic treatment and prevention of neonatal sepsis

The management of neonatal sepsis is challenging owing to complex developmental and environmental factors that contribute to inter-individual variability in the pharmacokinetics and pharmacodynamics of many antimicrobial agents. In this review, we describe (i) the changing epidemiology of early- and late-onset neonatal sepsis; (ii) the pharmacologic considerations that influence the safety and efficacy of antibacterials, antifungals, and immunomodulatory adjuvants; and (iii) the recommended dosing regimens for pharmacologic agents commonly used in the treatment and prevention of neonatal sepsis. Neonatal sepsis is marked by high morbidity and mortality, such that prompt initiation of antimicrobial therapy is essential following culture collection. Before culture results are available, combination therapy with ampicillin and an aminoglycoside is recommended. When meningitis is suspected, ampicillin and cefotaxime may be considered. Following identification of the causative organism and in vitro susceptibility testing, antimicrobial therapy may be narrowed to provide targeted coverage. Therapeutic drug monitoring should be considered for neonates receiving vancomycin or aminoglycoside therapies. For neonates with invasive fungal infections, the development of new antifungal agents has significantly improved therapeutic outcomes in recent years. Liposomal amphotericin B has been found to be safe and efficacious in patients with renal impairment or toxicity caused by conventional amphotericin B. Antifungal prophylaxis with fluconazole has also been reported to dramatically reduce rates of neonatal invasive fungal infections and to improve long-term neurodevelopmental outcomes among treated children. Additionally, several large multicenter studies are currently investigating the safety and efficacy of oral lactoferrin as an immunoprophylactic agent for the prevention of neonatal sepsis.

The secretory IgA system in the neonatal period

It is still not known when the secretory IgA response, important for defence of the mucous membranes, becomes fully competent in the human infant. The infant is, however, provided with 0.25--0.5 g of secretory IgA/day via the maternal milk. The milk contains secretory IgA antibodies against a wide variety of antigens from microorganisms, including bacteria, viruses and parasites. Many of the antibodies are directed against important virulence factors such as bacterial pili, enterotoxins, capsular polysaccharides and endotoxic lipopolysaccharides. The passive transfer of antibodies through the milk may explain why breast-fed infants are resistant to enteric infections in particular. The antibodies in the milk are often directed against antigens in the mother's milieu and intestine. An entero-mammary gland link, possibly consisting of lymphoid cells homing from the Peyer's patches in the intestine to the mammary gland, has been suggested. A limited selective uptake of oligomeric IgA from serum in exocrine glands, including the mammary glands, has also been indicated. Whichever the mechanism, the antibodies transferred via breast milk are composed to meet the needs of the infant.

The immunological components of human milk

Breast-feeding is generally accepted as the optimal method of feeding infants. However, we have yet to fully understand the complex mixture of bioactive compounds contained in human milk. Epidemiological studies have indicated that breast-feeding is associated with health benefits in the infant for many immune-related conditions. Breast milk contains various antimicrobial substances, factors that promote immune development, constituents that promote tolerance/priming of the infant immune system, as well as anti-inflammatory components. This chapter identifies and discusses the immunological compounds in human milk and the available evidence for their effect on the immune system of the infant. Current feeding regimens recommended for infants are based primarily on the current understanding of the nutritional requirements of the neonate, but perhaps will be modified to reflect the consequences on immune function both immediate and later in life.

From folklore to fact: the rhetorical history of breastfeeding and immunity, 1950-1997

This article examines the recent construction of human milk's immune-protective qualities as scientific fact, demonstrating that long-standing controversies about human milk's immune-protective effects have not been resolved by a particular scientific discovery. Rather, experts' consensus on how to respond to this uncertainty has been transformed, and this transformation has had as much to do with a change in the metaphor that governs interpretation of evidence about immune protection as it has with discovering new evidence about either human milk or the antibodies in it.

Breast feeding and the intestinal microflora of the infant--implications for protection against infectious diseases

Human breast milk contains an array of factors with anti-infectious potential, such as immunoglobulins (especially secretory IgA), oligosaccharides and glycoproteins with anti-adhesive capacity, and cytokines. Breast-feeding is associated with protection from the following infections or infection-related conditions: gastroenteritis, upper and lower respiratory tract infection, acute otitis media, urinary tract infection, neonatal septicaemia and necrotizing enterocolitis. Some of the protective effects may derive from an altered mucosal colonization pattern in the breast-fed infant. In other instances breast-fed infants develop less symptoms to the same microbe which causes disease in the bottle-fed infant. An example of an altered colonization pattern is that breast-fed infants have less P-fimbriated, but more type 1-fimbriated E. coli. This may protect against urinary tract infection in the breast-fed infant since P. fimbriae are the major virulence factor for urinary tract infection. An example of changed consequences of the same microbial colonization is that secretory IgA in the breast-milk protects very efficiently from translocation of intestinal bacteria across the gut mucosa by coating intestinal bacteria and blocking their interaction with the epithelium. This mechanism may protect the infant from septicaemia of gut origin and, possibly, necrotizing enterocolitis. Breast-milk is also highly anti-inflammatogenic and contains hormone like factors which counteract diarrhea. Thus, breast-fed infants may be colonized by recognized diarrheal pathogens and still remain healthy. Due to a less virulent intestinal microflora and decreased translocation breast-fed infants will obtain less stimuli for the gut immune system, resulting, in e.g., lower salivary IgA antibody titres.

Elevated levels and different repertoire profile of colostral anti-LPS antibodies may have a significant role in compensating newborn immunity

A high prevalence of systemic infections caused by enterobacteria such as Escherichia coli is observed during the neonatal period. Lipopolysaccharide (LPS) is one of the major factors responsible for septic shock caused by these Gram-negative bacteria. We have recently demonstrated the presence of anti-LPS immunoglobulin (Ig)G antibodies in cord blood with a repertoire identical to that found in maternal serum. In the present study, we analyzed anti-LPS O111 antibody isotypes in maternal serum and colostrum from mothers and in cord serum from their respective full-term (n = 30) and preterm (n = 13) neonate infants. The main isotype found in serum samples from mothers of term infants was IgM (range between 28 and 54 mg/l), followed by IgA (1-2 mg/l) and IgG (2-3 mg/l). The range of IgG antibody concentrations in cord blood was between 2 and 3 mg/l, as a result of placental transfer. A novel observation in our study was that the LPS bands recognized by colostral antibodies were completely different from those recognized by IgG in serum. Colostral IgA antibodies recognized several bands not bound by serum IgG antibodies from the respective maternal serum, independently of the antibody quantity. In addition, we verified the pattern of LPS recognition by serum IgA and colostral IgA antibodies was identical, what suggested that the antibody isotype found in serum could probably be derived from differentiated IgA-positive cells which were homing to the mucosa through the mucosal homing mechanism. Identical pattern of recognition was obtained comparing the IgA and IgM isotypes in colostrum. Slight differences in the pattern of recognition were found between colostral and serum IgM antibodies. The fact that colostral antibodies recognize much more bands than serum antibodies may be important for the host to mount an effective immune response in the intestinal lumen, in order to prevent excessive absorption of LPS, reducing possible systemic effects caused by the molecule.

Can improvements in breast-feeding practices reduce neonatal mortality in developing countries?

OBJECTIVE

to review the literature on the relationship between breast-feeding practices in the first month of life and neonatal mortality.

METHODS

Medline and Cochrane databases were searched using the keywords breastfeeding, and neonatal mortality, supplemented with additional searches using the keywords developing countries, colostrum, infant feeding and infant mortality, hypoglaecemia, hypothermia, breastfeeding practices, and suckling.

FINDINGS

breast feeding helps prevent hypothermia and hypoglycaemia in newborn babies, which are contributory causes of early neonatal deaths especially among low birth weight and premature babies. During the late neonatal period, most deaths in developing countries are due to infections such as sepsis, acute respiratory tract infection, meningitis, omphalitis and diarrhoea. Feeding colostrum and breast feeding, especially exclusive breast feeding, protects against such deaths.

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

in most developing countries, nearly all women breast feed in the first month of life, but often breast feeding is delayed beyond the first hour after birth, and exclusive breast feeding is not usually practised. Policies and training of staff of maternity centres and hospitals can encourage early initiation of breast feeding and exclusive breast feeding. Midwives can support community-based efforts to support exclusive breast feeding. Breast feeding plays an important role in reducing neonatal mortality and should be strongly emphasised by programmes attempting to reduce neonatal mortality.

Human developmental biology of granulocyte colony-stimulating factor

The availability of granulocyte colony-stimulating factor (G-CSF) has influenced the management of neonates with neutropenia. Since the first use of G-CSF in a neonate with neutropenia, much has been learned about the cellular sources and physiologic roles of G-CSF. This article reviews our present understanding of G-CSF and its cognate receptor in the fetus and neonate.

Granulocyte colony-stimulating factor is present in human milk and its receptor is present in human fetal intestine

OBJECTIVE

Human milk provides neonates with a meaningful degree of protection from infection, but the responsible mechanisms are not well understood. Discovering these mechanisms is important, because of the possibility of supplementing infant formulas with factors that simulate human milk's protective capacity. We postulated that granulocyte colony-stimulating factor (G-CSF), a cytokine known to augment antibacterial defenses through its salutory effect on neutrophil production, might be one such factor. To test this hypothesis, we quantified G-CSF in milk of healthy women and those with intraamniotic infection, and sought the presence of functional G-CSF receptors (G-CSF-R) in fetal/neonatal intestinal villi.

STUDY DESIGN

G-CSF was measured by enzyme-linked immunoassay in 126 milk samples obtained from breast-feeding women, and the concentrations were analyzed according to gestational age, postpartum day of collection (first 2 days vs greater 2 days), and the presence versus absence of intraamniotic infection. G-CSF-R messenger ribonucleic acid transcripts were sought from fetal/neonatal intestine using reverse transcriptase polymerase chain reaction, and localized using in situ RT-PCR. G-CSF-R protein, and specific intracellular signaling proteins (Janus tyrosine kinase-1, Janus tyrosine kinase-2, and tyrosine kinase-2), were sought by immunohistochemistry.

RESULTS

All milk samples contained G-CSF, and significantly more G-CSF was contained in milk collected during the first 2 postpartum days than during subsequent days. Milk from women who delivered prematurely had less G-CSF during the first 2 postpartum days than milk from women who delivered at term. When intraamniotic infection was present, the concentration of G-CSF in milk was elevated significantly compared with concentrations in milk of noninfected women. G-CSF concentrations were also higher in milk collected during the first 2 postpartum days from women who had received intrapartum recombinant G-CSF treatment, compared with milk obtained from women with intraamniotic infection, regardless if they delivered prematurely or at term. G-CSF-R messenger ribonucleic acid and protein were expressed on fetal villus enterocytes, and Janus tyrosine kinase-1, Janus tyrosine kinase-2, and tyrosine kinase-2 were present within the cytoplasm of these cells.

CONCLUSIONS

Human milk contains substantial quantities of G-CSF. G-CSF-R are abundant on villus enterocytes, and specific proteins associated with G-CSF-R signaling are present in these cells.

Concentrations of granulocyte colony-stimulating factor in human milk after in vitro simulations of digestion

Human milk contains proteins that survive digestion in the neonatal gastrointestinal tract. Our group and others have reported that granulocyte colony-stimulating factor (G-CSF), a hematopoietic cytokine that influences neutrophil proliferation and differentiation, is present in human milk. We also reported that specific receptors for G-CSF are expressed on the villous enterocytes of neonates. However, the physiologic role of milk-borne G-CSF is not known. Thus, we sought to evaluate the capacity of human milk to protect G-CSF against proteolytic degradation after exposure to gastric secretions obtained from preterm (PT) and term (T) neonates at pH concentrations of 3.2, 5.8, and 7.4. Specifically, we examined degradation of 1) endogenous G-CSF in PT (n = 15) and T (n = 15) human milk; 2) recombinant human G-CSF (rhG-CSF) added to a protein-free buffer (n = 10, 5 PT and 5 T); and 3) rhG-CSF added to human milk (n = 12, 6 PT and 6 T), various commercially prepared infant formulas (n = 15), and cow's milk (n = 5). Endogenous G-CSF and rhG-CSF added to human milk resisted degradation at 1 and 2 h. However, when rhG-CSF was added to commercial formulas, >95% was degraded at 1 and 2 h at each pH level. Similarly, approximately 60% of rhG-CSF added to cow's milk was degraded at I and 2 h. We conclude that 1) endogenous G-CSF and rhG-CSF added to human milk are protected from degradation after exposure to gastric secretions at physiologic pH levels, 2) rhG-CSF added to infant formulas is not protected from degradation, and 3) it is likely that the G-CSF present in human milk is biologically available to the neonate.

Human milk and host defence: immediate and long-term effects

Convincing studies demonstrate significant protection during breastfeeding against diarrhoea, respiratory tract infections, otitis media, bacteraemia, bacterial meningitis, botulism, urinary tract infections and necrotizing enterocolitis. There is also good evidence for enhanced protection for years after the termination of breastfeeding against Haemophilus influenzae type b infections, otitis media, diarrhoea, respiratory tract infections and wheezing bronchitis. In some reports breastfeeding has also improved vaccine responses. Several studies show that milk may actively stimulate the immune system of the offspring via transfer of anti-idiotypic antibodies and lymphocytes. This may explain why breastfeeding diminishes the risk of developing coeliac disease. Some investigations suggest that there may also be a similar effect on allergic diseases and autoimmune diseases, as well as inflammatory bowel diseases and certain tumours. This needs to be confirmed.

Neonatal mortality in a rural area of The Gambia

Childhood mortality in Upper River Division, The Gambia is high, 99 per 1000 mid-year population, and 27% of deaths occur is the neonatal period. The aims of the present study were to describe patterns of neonatal death and to identify risk factors. Cause of death was investigated using a neonatal post-mortem questionnaire, and a population-based, matched case-control study was conducted to identify potential risk factors. The neonatal mortality rate in Upper River Division was 39 per 1000 live births (95% CI 36.8-41.2). The rates in the early and late neonatal periods were 21.0 (19.4-22.6) and 18.0 (16.5-19.5), respectively. Infection accounted for 57% of all deaths. In the early neonatal period, 30% of deaths were due to prematurity. Only 55% of babies who died presented for treatment and 84% died at home. Risk factors for neonatal death were primiparity (OR 2.18), previous stillbirth (OR 3.19), prolonged labour (OR 2.80) and pre-lacteal feeding (OR 3.38). A protective effect was seen in association with delivery by a trained traditional birth attendant (OR 0.34) and the application of shea nut butter, a traditional medicine, to the cord stump (OR 0.07). This study has identified the need to understand the reasons underlying the widespread use of pre-lacteal feeds and the barriers to health service use in this community in order to plan effective interventions.

Breastfeeding provides passive and likely long-lasting active immunity

OBJECTIVES

The reader of this review will learn about the mechanisms through which breastfeeding protects against infections during and most likely after lactation, as well as possibly against certain immunologic diseases, including allergy.

DATA SOURCES

I have followed the literature in the area closely for the last 30 to 40 years and have made repeated literature searches through MEDLINE, most recently in 1998. Textbooks and peer-reviewed journals have been sought for, as well as books representing meeting reports in English, French, German, and Spanish.

RESULTS

Human milk protects against infections in the breastfed offspring mainly via the secretory IgA antibodies, but also most likely via several other factors like the bactericidal lactoferrin. It is striking that the defense factors of human milk function without causing inflammation, some components are even directly anti-inflammatory. Protection against infections has been well evidenced during lactation against, e.g., acute and prolonged diarrhea, respiratory tract infections, otitis media, urinary tract infection, neonatal septicemia, and necrotizing enterocolitis. There is also interesting evidence for an enhanced protection remaining for years after lactation against diarrhea, respiratory tract infections, otitis media, Haemophilus influenzae type b infections, and wheezing illness. In several instances the protection seems to improve with the duration of breastfeeding. Some, but not all studies have shown better vaccine responses among breastfed than non-breastfed infants. A few factors in milk like anti-antibodies (anti-idiotypic antibodies) and T and B lymphocytes have in some experimental models been able to transfer priming of the breastfed offspring. This together with transfer of numerous cytokines and growth factors via milk may add to an active stimulation of the infant's immune system. Consequently, the infant might respond better to both infections and vaccines. Such an enhanced function could also explain why breastfeeding may protect against immunologic diseases like coeliac disease and possibly allergy. Suggestions of protection against autoimmune diseases and tumors have also been published, but need confirmation.

CONCLUSIONS

Breastfeeding may, in addition to the well-known passive protection against infections during lactation, have a unique capacity to stimulate the immune system of the offspring possibly with several long-term positive effects.

Evolution of immunologic functions of the mammary gland and the postnatal development of immunity

Physiologic delays in production of immune factors occur in mammals including Homo sapiens. This finding is counter to a basic tenet of biologic evolution, because such delays increase the risk of infections. The disadvantage is, however, offset by defense factors in milk of the species in whom the developmental delay occurs. Reciprocal relationships between the production of immune factors by the lactating mammary gland and the production of those defense agents during early infancy are found in all investigated mammalian species. Thus, the evolution of these processes is closely related. Certain immunologic components of milk are highly conserved, whereas others vary according to the species. The variations most likely evolved by genetic mutations and natural selection. In addition, the immune composition of mammalian milks is associated with developmental delays in the same immunologic agents. Furthermore, most closely related mammals, such as humans and chimpanzees, are most similar in the defense agents in their milks and the corresponding developmental delays in their immune systems. Defense factors in human milk include antimicrobial agents (secretory IgA, lactoferrin, lysozyme, glycoconjugates, oligosaccharides, and digestive products of milk lipids), antiinflammatory factors (antioxidants, epithelial growth factors, cellular protective agents, and enzymes that degrade mediators of inflammation), immunomodulators (nucleotides, cytokines, and antiidiotypic antibodies), and leukocytes (neutrophils, macrophages, and lymphocytes). Because of a lack of geographic/ethnic variation in the immunologic composition of human milk and corresponding immunologic delays in infants, these evolutionary processes seem stable. This is supported by investigations of diverse populations that indicate that this evolutionary outcome is highly beneficial to human infants.

Intestinal oxygenation and mucosal permeability with luminal mother's milk in developing piglets

We have previously observed a developmental difference in mucosal permeability (i.e. the younger the animal, the greater the increase in permeability) after exposure to luminal nutrients derived from cow's milk-based infant formulas. There has been tremendous speculation and some clinical evidence that mother's milk may be protective against mucosal injury in developing intestine. In this study, we hypothesized that instillation of sow's milk into the intestinal lumen of developing piglets would cause no differences in either intestinal metabolic demand (oxygen uptake) or mucosal permeability among age groups. Intestinal blood flow (total and fractionated), arteriovenous oxygen content difference, venous pressure, and capillary pressure were measured, and vascular resistance and oxygen uptake were calculated, after 30 min of intraluminal instillation of predigested and solubilized sow's milk in 1-d-old, 3-d-old, 2-wk-old, and 1-mo-old piglet jejunoileum. In a separate group of animals, plasma-to-lumen clearance of chromium-51 EDTA was evaluated during luminal perfusion with digested and solubilized sow's milk in 1-d-old, 3-d-old, and 1-mo-old piglet jejunoileum. Intestinal oxygen uptake was similar among age groups of developing piglets, but EDTA clearance was significantly higher for intestinal segments perfused with sow's milk in 1-d-old, compared with older, animals. Thus, luminal perfusion with predigested and bile acid-solubilized sow's milk in 1-d-old piglet jejunoileum, compared with perfusion in older piglets, causes increased mucosal permeability in 1-d-old intestine, but this increased permeability is not due to increased intestinal oxygen uptake (i.e. increased metabolic demand).

Effect of early nutritional deprivation and diet on translocation of bacteria from the gastrointestinal tract in the newborn rat

The gastrointestinal (GI) barrier function is immature in the preterm neonate and might thus facilitate translocation of enteric bacteria and gut-derived septicemia. Circumstantial evidence suggests that bacterial uptake from the intestine may be further enhanced by an alteration of the host nutritional status. To test this hypothesis, neonatal rats were fed normal or restricted amounts of either breast milk or of a rat milk-simulated formula for 3-5 d. At the end of the study, various sections of the GI tract, mesenteric lymph nodes, liver, spleen, and blood were analyzed for bacteria using standard microbiologic procedures. Normal breast feeding was associated with bacterial translocation to mesenteric lymph nodes and in some cases to liver or spleen in 27% of rats, whereas all bacterial cultures were negative in a control group killed immediately after birth. Restricted breast feeding did not increase translocation compared with normal breast feeding. By contrast, feeding normal or restricted amounts of formula increased the numbers of gut bacteria by 2-3 logs, altered the morphology of the small intestinal mucosa, and resulted in ample bacterial translocation to the mesenteric lymph nodes and to systemic organs including the blood. Bacterial translocation may normally occur in suckling neonatal rats and is not increased by food restriction. Artificial feeding dramatically enhances translocation of gut bacteria.

Anti-alpha-galactosyl immunoglobulin A (IgA), IgG, and IgM in human secretions

Anti-alpha-galactosyl (anti-Gal) is a natural human serum antibody that binds to the carbohydrate Gal alpha 1,3Gal beta 1,4GlcNAc-R (alpha-galactosyl epitope) and is synthesized by 1% of circulating B lymphocytes in response to immune stimulation by enteric bacteria. We were able to purify secretory anti-Gal from human colostrum and bile by affinity chromatography on silica-linked Gal alpha 1,3Gal beta 1,4GlcNAc. We found similar secretory anti-Gal antibodies in human milk, saliva, and vaginal washings. Secretory anti-Gal from milk and saliva was exclusively immunoglobulin A (IgA); that from colostrum and bile also contained IgG and IgM isotypes. Serum was also found to contain anti-Gal IgM and IgA in addition to the previously reported IgG. Anti-Gal IgA purified from colostrum and bile had both IgA1 and IgA2. Secretory anti-Gal from saliva, milk, colostrum, and bile agglutinated rabbit erythrocytes (RRBC) and bound to bovine thyroglobulin, both of which have abundant alpha-galactosyl epitopes. The RRBC-hemagglutinating capacity of human saliva, milk, bile, and serum was specifically adsorbed by immobilized Gal alpha 1,3Gal beta 1,4GlcNAc but not by Gal alpha 1,4Gal beta 1,4GlcNAc, Gal beta 1,3GalNAc, Gal beta 1,4GlcNAc, Gal beta 1,4GlcNAc alpha 1,2Man, or Fuc alpha 1,2Gal beta 1,4GlcNAc. No RRBC-hemagglutinating activity could be detected in rat milk, rat bile, cow milk, or rabbit bile, suggesting a restricted species distribution for secretory anti-Gal similar to that found for serum anti-Gal. Colostral anti-GaI IgA bound strongly to a sample of gram-negative bacteria isolated from the throats and stools of well children as well as to an Escherichia coli K-1 blood isolate. Colostral anti-GaI IgA inhibited the binding of a Neisseria meningitidis strain to human buccal epithelial cells, suggesting that this antibody may play a protective role at the mucosal surface.

Age at breast feeding start and postneonatal growth and survival

Colostrum has important anti-infective properties. It may also somehow promote the development of the child's immunological system. Discarding colostrum, as practised in some cultures, could thus have adverse health consequences beyond the neonatal period. To test this hypothesis, the age at breast feeding start of 734 healthy newborns in urban Guinea-Bissau was ascertained. The children were then prospectively followed up to 3 years of age. Eighty nine deaths occurred during the study. The probability of death in the age interval 28 days to 3 years was about 20%. The child's age at breast feeding start had no statistical impact on postneonatal growth or survival. As a single measure, early breast feeding start is not likely to make much difference for the long term growth or survival of children living under material poverty conditions.

Breast feeding and protection against neonatal sepsis in a high risk population

Protection against neonatal sepsis by breast feeding was investigated in a developing community. A case-control study was carried out with 42 cases from a hospital and 270 controls, matched for age and socioeconomic conditions from the community. Exclusive breast feeding was extremely rare, most babies being partially breast fed and a few being given formula feed or animal milk. A highly significant odds ratio of 18 was obtained, showing that even partial breast feeding protects against neonatal sepsis in such a population.

Phenotypic differences and characteristics of pyelonephritogenic strains of Escherichia coli isolated from children and adults

We examined the frequency of bacterial strains expressing cell surface hydrophobicity, P-fimbriae, mannose-resistant haemagglutination (MRHA), type I fimbriae, production of aerobactin, haemolysin synthesis (Hly), production of cytotoxic necrotising factor (CNF) and HeLa cell adherence in 126 strains of Escherichia coli isolated from children (n = 65) and women (n = 61) with acute non-obstructive pyelonephritis. Previous investigations have shown that pyelonephritogenic strains of E. coli more often express hydrophobic properties, P-fimbriae, MRHA, aerobactin-mediated iron uptake, Hly and CNF production than strains isolated from the faecal flora of healthy persons. The objective of the present study was to examine phenotypic differences between strains of E. coli obtained from children with their first episode of acute pyelonephritis and strains from women with non-obstructive acute pyelonephritis. Of the pyelonephritogenic strains of E. coli isolated from children, 98% expressed cell surface hydrophobic properties compared to 82% isolated from adults (P = 0.004). Strains from children and adults had the same ability to assimilate iron and equally often expressed P-fimbriae, MRHA and type I fimbriae. Strains from children with acute pyelonephritis more significantly expressed Hly (72%) and CNF (58%) than did pyelonephritogenic strains from adults (49 and 37% respectively, P = 0.013 and P = 0.028 respectively). The frequency of HeLa cell adherence was similar and low in both groups. The phenotype aerobactin+ Hly+ and Hly+CNF+ was found significantly more often in pyelonephritogenic strains from children than in strains from adults (P = 0.006 and P = 0.028 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Human breast milk T lymphocytes display the phenotype and functional characteristics of memory T cells

Naive (unsensitized) and memory (antigen-primed) T cells can be phenotypically distinguished on the basis of the high or low intensity with which they express a number of immunologically relevant lymphocyte membrane antigens, including CD45R, CDw29, UCHL1, LFA-1, LFA-3, CD2 and Pgp-1. Here we report that in contrast to the two major T cell subsets found in the blood, milk T lymphocytes are almost exclusively composed of the one which exhibits the CD45Rlow, CDw29, UCHL1, LFA-1high memory T cell phenotype. In addition, while milk and autologous blood cells expressed similar levels of CD3 surface antigens, CD2 and ICAM-1 expression was approximately twofold greater on the milk T lymphocytes. This agrees with the finding that whereas colostrum T cells respond poorly to PHA, they proliferate and produce interferon-gamma normally when stimulated with either the anti-CD3 or anti-CD2 monoclonal antibodies. The selective colonization of the mammary gland during lactation by a population of T lymphocytes which displays the phenotype and functional characteristics of memory T cells may be one of the mechanisms whereby the suckling infant benefits form its mother's immunological experience.

Preliminary study of breastfeeding and bacterial adhesion to uroepithelial cells

The oligosaccharide content of breast-milk and urine from ten nursing mothers and their babies, collected 30 days after delivery, was analysed by thin-layer and high-performance liquid chromatography. Each woman's milk and urinary oligosaccharide profiles were very similar, and the pattern of oligosaccharides excreted by her infant was also strongly correlated with that of her milk. The babies excreted 300-500 mg/day oligosaccharides and the mothers 500-800 mg/day. The effect of oligosaccharide fractions from a 500 ml pool of colostrum on bacterial adhesion to uroepithelial cells was tested on a strain of Escherichia coli isolated from an infant with urinary tract infection. The high-molecular-weight sialylated oligosaccharides had no effect but neutral oligosaccharides caused inhibition of bacterial adhesion which rose as the size of the oligosaccharides decreased. These findings suggest that breastfeeding may have a preventive effect on urinary tract infection in both mother and infant.

Human milk for low birthweight infants: immunology, nutrition and newer practical technologies

Human milk has a number of unique properties which can be of benefit to high risk low birthweight and preterm infants. Immunological features are of particular importance. Growth is better with the use of the mother's own milk than with pooled bank milk. The quality of the latter can be improved by various measures noted in the text. Growth can be further improved by enriching the milk with human milk factors, powder formula or protein supplements. As breast-feeding is best for infants, the maternal milk supply should be maintained during the hospital stay of infants by frequent expression, galactogogues used where necessary under supervision, encouraging maternal contact with the infant, promotion of suckling initially on the "empty" breast after expression of milk, and subsequently institution of direct breast-feeding. With proper interventions and motivation of both staff and mothers, even very low birthweight infants below 1,500 gm can go on, in time, to exclusive breast-feeding.

In vivo distribution of human milk leucocytes after ingestion by newborn baboons

The in vivo distribution of enterally administered human milk leucocytes labelled with indium hydroxyquinoline (111In) was studied in premature baboons. The animals were killed at 72 hours of age and tissue samples examined for radioactivity. Maximum activity was found in the luminal contents, and activity in the liver and spleen was higher than in bone marrow, the site where free isotope is normally deposited. These findings suggest that some intact milk leucocytes may cross from the gastrointestinal tract into the neonatal circulation. Also the high activity in gastrointestinal tissue that had been washed several times indicates that leucocytes adhere to mucosa or lie intramurally. We speculate that the presence of leucocytes in the gastrointestinal tract 60 hours after a single breast feed can provide an important defence mechanism against infection.

The prevalence of bacteriuria among high risk neonates in Nigeria

Among the 446 high risk neonates studied for significant bacteriuria and pyuria in the neonatal wards of the Obafemi Awolowo University teaching hospital Complex, Ile-Ife, 7.6% and 5.8% were positive for significant bacteriuria and pyuria respectively, while none of the 81 infants in the control group were positive. Males and females were similarly affected and there was no seasonal variation in the prevalence of pyuria or bacteriuria. It is noteworthy that 25 (96%) of the 26 pyuria neonates also had bacteriuria emphazising the significance of pyuria as a possible screening method for urinary tract infections in neonates. The clinical problems in the neonates studied included prematurity, low birthweight, neonatal jaundice, fever, CNS symptoms, ophthalmia neonatorum, prolonged rupture of the membranes (PROM), respiratory distress, septic cord/skin, diarrhoea, vomiting and feeding problems. Only prematurity and low birthweight were significantly associated with bacteriuria in the neonates studied. The organisms encountered in this study were Escherichia coli (58.4%), Klebsiella species (35.3%) and Proteus species (5.9%). Of the bacterial isolates, 67% were sensitive to Ampicillin and 97% to Gentamycin. The combination of these antibiotics was effective in all cases in the present study. The study has highlighted the need for routine urine culture in our high risk neonates.

Uptake of lymphocytes fed to suckling rats. An autoradiographic study of the transit of labeled cells through the neonatal gastric mucosa

To determine the potential for transfer of maternal lymphocytes to the newborn during suckling, radiolabeled cells were fed to rat neonates of different ages and autoradiographs prepared from tissue sections obtained from the stomach and small intestine. The entire stomach (including contents) and intestinal walls were observed using semiserial 3 micron methacrylate plastic sections. For these studies 100 X 10(6) [3H]uridine-labeled lymph node cells were fed to 1-4-day-old neonates using a smooth-tipped intubation needle. Some of the lactating female rats had been given radioisotope prior to delivery and "cold" babies were fostered to them to enhance the number of labeled cells in the neonatal digestive tract. Babies were killed at 1, 2, 4, 8, 24 and 48 h after feeding. The stomach contents showed a considerable number of labeled cells (32% at 1 h after feeding) and many of these cells were in close proximity to the epithelium. The gastric epithelium often exhibited gaps between adjacent epithelial cells similar to those we have previously reported in the lactating mammary epithelium, and labeled cells were observed in the immediate area of the gaps. Labeled cells were seen in the neonatal gastric epithelium, lamina propria, mesenteric attachments, in the wall and lumen of small gastric blood vessels and adjacent lymph nodes. Labeled cells were most abundant in the gastric wall at 1-2 h following feeding, indicating that transit through the epithelium occurred rapidly. Although labeled cells were seen in the lumen of the small intestine, none were observed in the tissues of the intestinal wall. When heat-killed labeled cells were fed, no labeled cells were seen in the tissues of the neonatal gastrointestinal tract. It is apparent from these studies that a portion of the leukocytes that are delivered to the neonate during suckling are able to transit the gastric epithelium and establish themselves in the neonate's tissues, presumably to aid in the protection of the immunologically naive infant.

Effect of iron on serotypes and haemagglutination patterns of Escherichia coli in bottle-fed infants

Strains of Escherichia coli isolated from faecal specimens of ten infants receiving breast milk, six receiving a cow-milk preparation with iron supplement (5 mg/l) and six the preparation without iron supplement (less than 0.5 mg/l), were serotyped and examined for their haemagglutinating activity. The Escherichia coli flora of breast-fed and bottle-fed infants consisted of one resident strain, accompanied by one or more transient strains. Changes in the serotype of the Escherichia coli flora and in the frequency of occurrence of strains associated with urinary tract infections were more often seen in bottle-fed than in breast-fed infants. In breast-fed and bottle-fed infants without iron supplement most strains of Escherichia coli were non-haemagglutinating, while most strains in infants bottle-fed with iron supplement showed mannose-resistant haemagglutination. It is concluded that human milk favours the establishment of a stable non-pathogenic Escherichia coli flora and that a low iron content in standard cow-milk preparation favours colonization with non-adherent strains of Escherichia coli.

Cellular immunity in human milk

The responses of human milk lymphocytes (MIL) to a variety of immunogenic stimuli were studied and compared to those of peripheral blood lymphocytes (PBL) from the milk donors. MIL showed a decreased proliferative response to mitogens and allogeneic leukocytes in vitro but displayed the ability to stimulate alloreactivity equivalent to PBL. Neither pretreatment with cell-free autologous milk nor co-cultured MIL were capable of suppressing the proliferative responses of PBL. Moreover, macrophages isolated from milk and pulsed with soluble antigen or allogeneic cells effectively induced proliferation by peripheral blood T cells whereas the response of milk nonadherent cells to antigen presented by peripheral macrophages was very low. MIL respond better to pathogenic enteric E. coli than PBL not as well as PBL to Yersinia enterocolitica. Treatment of MIL with monoclonal antibodies cytotoxic for T cells abolished their response to bacterial antigens. Application of an anti HLA class II antigen monoclonal antibody to mixed lymphocyte or lymphocyte-bacteria cultures resulted in substantial inhibition of the MIL response similarly to that of PBL. The relevance of these data to the immunological needs of the neonate are discussed.

Comparison of the cellular cytotoxic activities of colostral lymphocytes and maternal peripheral blood lymphocytes

Colostral lymphocytes (CL) from mothers 2 to 4 days post-partum and autologous maternal peripheral blood lymphocytes (PBL) were investigated for (1) natural killer (NK) and antibody-dependent cellular cytotoxic (ADCC) activities, (2) target binding ability, (3) interferon (IFN)- and interleukin 2 (IL2)-induced augmentation of NK activity, (4) lectin-dependent cellular cytotoxicity (LDCC), and (5) the ability of culture-derived soluble suppressor factor(s) to inhibit the NK activity of normal allogeneic lymphocytes. CL depleted of adherent cells and Percoll-separated NK-enriched subpopulations of CL demonstrated significantly lower NK and ADCC activities compared to autologous PBL. However, the target binding ability of CL was comparable to autologous PBL. Although the residual NK activity of CL was augmented by IFN and IL2, the activity was not enhanced to the same level shown by autologous PBL. CL also demonstrated a significant enhancement of LDCC activity, although the activity was not stimulated to the levels shown by PBL. Culture supernates of CL manifested greater suppression of the NK ability of allogeneic PBL than culture supernates produced by autologous PBL. These results are consistent with a model that suggests differential partitioning of lymphocyte subpopulations between colostrum and peripheral blood.

Relationship of breast feeding versus bottle feeding with emergency room visits and hospitalization for infectious diseases

Breast-feeding habits of 480 Jewish infants visiting a pediatric emergency room (ER) with infectious diseases were compared to those of 502 healthy infants visiting maternal-child health centers (MCH). (These centers are attended by almost 100% of the Jewish infant population.) Among infants under 5 months of age with acute gastroenteritis and upper respiratory infections, breast feeding was significantly less prevalent than among age-matched infants in the MCH group (22.6%, 18.5% and 53.4% respectively, P less than 0.0001). Infants with acute otitis media and lower respiratory tract infections showed the same trend although the numbers were small. A very short breast-feeding period of 2 weeks or less was more prevalent among the ER group and was associated with increased hospitalization rate. These data emphasize the importance of breast milk in reduction of ER visiting and hospitalization rate.