Passive acquisition of anti-Staphylococcus aureus antibodies by newborns via transplacental transfer and breastfeeding, regardless of maternal colonization

OBJECTIVE: To investigate the transmission of anti-Staphylococcus aureus (Sa) IgG, IgG1 and IgG2 via placental transfer and the transfer of IgA via the colostrum according to maternal Sa carrier status at delivery. METHODS: We evaluated anti-Sa IgG, IgG1 and IgG2 in maternal and cord sera and IgA in colostrum from a case (n=49, Sa+) and a control group (n=98, Sa-). RESULTS: Of the 250 parturients analyzed for this study, 49 were nasally colonized with S. aureus (prevalence of 19.6%). Ninety-eight non-colonized subjects were selected for the control group. The anti-Sa IgG, IgG1 and IgG2 levels and the IgG avidity indexes in the maternal and cord sera did not differ between the groups, with a low transfer ratio of anti-Sa IgG to the newborns in both groups. The anti-Sa IgG2 titers were significantly higher than the IgG1 titers in the maternal and cord sera. Inversely, the transfer ratios were higher for anti-Sa IgG1 compared with IgG2; however, no differences between the groups were detected. The Sa-specific IgA levels and avidity indexes in the colostrum were equivalent between groups. CONCLUSIONS: Maternal Sa nasal colonization at delivery is not associated with higher antibody levels in the mother or newborns. The high titers of anti-Sa IgG2 found in the cord serum indicate a greater reactivity with non-protein antigens, which may further contribute to the susceptibility to staphylococcal infections at birth. The presence of IgA in the colostrum with avidity to S. aureus reinforces the importance of breastfeeding shortly after birth.

Avaliação da transferência placentária e pelo colostro de anticorpos IgG e IgA anti-Staphylococcus aureus em mães com e sem colonização nasal / Evaluation of placental and colostral transfer of anti-Staphylococcus aureus IgG and IgA antibodies in mothers with and without nasal colonization

A transferência passiva de anticorpos da mãe para o filho auxilia na adaptação ao meio externo. No recém-nascido (RN), a colonização pelo Staphylococcus aureus (S. aureus) é precoce, sendo este um importante agente etiológico em infecções neonatais e no lactente jovem, para o qual ainda não se dispõem de vacina. OBJETIVOS: Avaliar as concentrações, títulos e avidez de anticorpos maternos anti-S. aureus do tipo IgG e IgA e a passagem desses anticorpos para os RN por transferência placentária e pelo colostro. MÉTODOS: Estudo caso-controle de 147 parturientes saudáveis. Foram coletadas amostras de soros maternos, de cordão umbilical e colostro. O grupo caso foi definido pela colonização nasal natural pelo S. aureus, sendo que para cada caso (n=49) foram selecionados 2 controles (n=98). Foram utilizadas as metodologias de imunoturbidimetria para dosagem de IgG total, ensaio imunoenzimático para dosagem IgA total e para a aferição das concentrações e títulos de anticorpos específicos anti-S. aureus (IgG sérica, subclasses séricas IgG1 e IgG2, IgA de colostro e os índices de avidez). Foram aplicados testes não paramétricos de Wilcoxon para amostras pareadas e de Mann-Whitney para amostras não pareadas, com intervalo de confiança de 95%, nível de significância p < 0,05. RESULTADOS: No grupo caso, as concentrações séricas de IgG total materna foram maiores mas com menor taxa de transferência placentária de IgG total, ocorrendo o inverso para o grupo controle. Não foram observadas diferenças nas concentrações séricas de IgG materna anti-S. aureus entre os grupos, mas com taxa de transferência placentária significantemente menor no grupo caso. Observou-se que os títulos específicos de IgG1 anti-S. aureus foram mais baixos no soro materno e no cordão do grupo caso, com taxas de transferência similar para os grupos caso e controle. Para os títulos específicos de IgG2 anti-S. aureus, não foram observadas diferenças entre os grupos caso e controle, com taxas de...

The passive transfer of antibodies from mother to child assists in adjustment to the external environment. In the newborn (NB), colonization by Staphylococcus aureus (S. aureus) occurs early, which is an important etiologic agent in neonatal and young infant infections, for which no vaccine is available. AIMS: To evaluate concentrations, titers and avidity of anti-S. aureus maternal IgG and IgA antibodies and transmission of these antibodies to the newborns via placental transfer and colostrum. METHODS: Case-control study of 147 healthy pregnant women. Samples of maternal serum, cord blood and colostrum were collected. The case group was defined by natural nasal colonization with S. aureus, and for each case (n = 49) were selected 2 controls (n = 98). Immunoturbidimetric assay was used to measure total IgG, and immunoenzymatic assay to measure total IgA in colostrum and anti-S. aureus concentrations and titers (serum IgG, serum IgG1 and IgG2, colostrum IgA and IgG and IgA avidity indexes). Nonparametric Wilcoxon test for paired samples and the Mann-Whitney test for unpaired samples were applied, with a confidence interval of 95%, significance level of p < 0.05. RESULTS: In the study group, maternal total IgG serum concentrations were higher but with lower total IgG placental transfer ratio, while the opposite occurred for the control group. No differences were observed in anti-staphylococcal maternal IgG serum concentrations between groups, but placental transfer ratio was significantly lower in the case group. It was observed that anti-S. aureus IgG1 titers were lower in maternal and cord serum from the case group, with with similar transfer ratios for case and control groups. Regarding antistaphylococcal IgG2 titers, no differences were observed between case and control groups, with similar transfer ratios between groups. It was observed that specific IgG2 titers were higher than those of IgG1 in both maternal and cord serum from both groups. In...