Multidrug-Resistant, Potentially Pathogenic Bacteria in Mother’s Milk, and Neonatal Oral and Rectal Swabs of Preterm Mother-Neonate Dyads

Preterm mother-neonate dyads are often exposed to broad-spectrum antibiotics. We studied preterm dyads for multidrug-resistant potentially pathogenic bacteria (MDR-PPB).To determine colonisation rates of MDR-PPB in mother’s milk and neonatal oral and rectal swabs and identify genetically identical strains across the 3 samples. We enrolled lactating mother-neonate dyads, and cultured milk and neonatal oral, rectal swabs under aseptic conditions. We identified bacteria using MALDI-TOF, focusing on a panel of 13 neonatal pathogens of interest. Sensitivity was tested using Vitek2. If the milk, oral, and rectal swab samples from a mother-neonate dyad showed the same species and antibiogram, multi-locus sequence type (MLST) was performed. Of 130 dyads screened, we enrolled 100. 14 milk samples (from 14 mothers) had pathogens of interest, including 9 (64%) MDR bacteria. 82 isolates were grown from the oral swabs (77 neonates), of which 58 (70.7%) were MDR. 130 isolates were grown from the rectal swabs (96 neonates), of which 104 (80%) were MDR. Two mother-neonate dyads had MDR Escherichia coli and Klebsiella pneumoniae species cultured from all three samples with identical antibiograms. On MLST, DNA sequencing analysis of the PCR products showed no variation at all 7 loci of E. coli (Sequence Type-405), whereas, with K. pneumoniae, variations were observed in 4 loci (infB, mdh, phoE,rpoB). An alarming proportion of preterm mother’s milk, oral swab and rectal swabs have MDR-PPB. MLST suggested that a pathogenic strain of E. coli was transmitted from mother’s milk to the neonate’s gut.