BackgroundThe purpose of this study was to identify potential predisposing factors associated with human infectious mastitis.MethodsWe conducted a case–control study among breastfeeding women, with 368 cases (women with mastitis) and 148 controls. Data were collected by a questionnaire designed to obtain retrospective information about several factors related to medical history of mother and infant, different aspects of pregnancy, delivery and postpartum, and breastfeeding practices that could be involved in mastitis. Bivariate analyses and multivariate logistic regression model were used to examine the relationship between mastitis and these factors.ResultsThe variables significantly- and independently-associated with mastitis were cracked nipples (P < 0.0001), oral antibiotics during breastfeeding (P < 0.0001), breast pumps (P < 0.0001), topical antifungal medication during breastfeeding (P = 0.0009), mastitis in previous lactations (P = 0.0014), breast milk coming in later than 24 h postpartum (P = 0.0016), history of mastitis in the family (P = 0.0028), mother-infant separation longer than 24 h (P = 0.0027), cream on nipples (P = 0.0228) and throat infection (P = 0.0224).ConclusionsValuable factors related to an increased risk of infectious mastitis have been identified. This knowledge will allow practitioners to provide appropriate management advice about modifiable risk factors, such as the use of pumps or inappropriate medication. They also could identify before delivery those women at an increased risk of developing mastitis, such as those having a familial history of mastitis, and thus develop strategies to prevent this condition.

Many coagulase-negative staphylococci, viridans group streptococci, and corynebacteria, usually dismissed as contaminant bacteria, may play an important role as etiologic agents of mastitis. Proper diagnosis of mastitis should be established after performing microbiological testing of milk based on standardized procedures. A reliable analysis must identify the mastitis-causing pathogen(s) at the species level and its(their) concentration(s).

Objectives Lactational mastitis frequently leads to a premature abandonment of breastfeeding; its development has been associated with several risk factors. This study aims to use a decision tree (DT) approach to establish the main risk factors involved in mastitis and to compare its performance for predicting this condition with a stepwise logistic regression (LR) model. Methods Data from 368 cases (breastfeeding women with mastitis) and 148 controls were collected by a questionnaire about risk factors related to medical history of mother and infant, pregnancy, delivery, postpartum, and breastfeeding practices. The performance of the DT and LR analyses was compared using the area under the receiver operating characteristic (ROC) curve. Sensitivity, specificity and accuracy of both models were calculated. Results Cracked nipples, antibiotics and antifungal drugs during breastfeeding, infant age, breast pumps, familial history of mastitis and throat infection were significant risk factors associated with mastitis in both analyses. Bottle-feeding and milk supply were related to mastitis for certain subgroups in the DT model. The areas under the ROC curves were similar for LR and DT models (0.870 and 0.835, respectively). The LR model had better classification accuracy and sensitivity than the DT model, but the last one presented better specificity at the optimal threshold of each curve. Conclusions The DT and LR models constitute useful and complementary analytical tools to assess the risk of lactational infectious mastitis. The DT approach identifies high-risk subpopulations that need specific mastitis prevention programs and, therefore, it could be used to make the most of public health resources.

There was a good agreement among the different methods assessed in this study to identify those isolates of the salivarius, mutans, and pyogenic groups, whereas unambiguous discrimination could not be achieved concerning some species of the mitis group ( S mitis, S pneumoniae, S pseudopneumoniae, S oralis).

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