Identification and characterization of resistance and pathogenicity of Enterococcus spp. in samples of donor breast milk

BACKGROUND: Breast milk is the primary source of nutrition for newborns. Hospitalized babies frequently need nutritional support from Human Milk Banks. As bacterial species of the genus Enterococcus are part of the microbiota of healthy donors, they may contaminate samples of pumped breast milk. AIM: To identify and characterize the bacterial virulence and resistance in samples isolated from the nipple-areolar region, hands, and breast milk aliquots from donors at the Human Milk Bank of Municipal Hospital Esaú Matos in the city of Vitória da Conquista, Bahia State, Brazil. METHODS: The personal hygiene and sanitation of donors were analyzed with the aim of identifying possible reasons for contamination of pumped milk. Cutaneous samples as well as aliquots of unpasteurized and pasteurized milk from 30 participants were obtained. Each Enterococcus spp. isolate underwent a disk diffusion susceptibility test and molecular biology techniques to determine resistance and virulence genes. RESULTS: Enterococcus spp. were identified in 30% of donors (n = 9), and 11 specimens were isolated. Resistance to tetracycline was highly prevalent, being detectable in 63% of the isolates (n = 7) and followed by intermediate sensitivity to ciprofloxacin, observed in 27% of the specimens (n = 3). The efaA gene was found in 63% (n = 7) of the isolates, while the ace gene was detected in 27% (n = 3). CONCLUSION: This study illustrates the importance of microbiological monitoring by Human Milk Banks and the need for alternatives to prevent the presence of Enterococcus spp. in hospital settings.