Background: Milk banks supply pasteurized donated human milk to preterm infants
where the maternal supply is insufficient. Studies have shown that donated human
milk may also be a source of pathogenic bacteria that may affect the infant’s health
due to their pathogenicity or toxicity. For this reason many milk banks screen milk
for bacteria using traditional culture-based methods.
Objective: This study was a retrospective audit that was conducted on bacteria
isolated from QC samples of batched breastmilk donated to the Perron Rotary Express
Milk (PREM) Bank at King Edward Memorial Hospital from 2007 to 2011. This
audit will (i) describe temporal associations between the bacterial content of
donations and the year and season of processing (ii) identify pathogenic bacteria
associated with donated milk and (iii) identify pathotoxigenic bacteria in donated
HM.
Methods: The sample size was 2890 batches that were donated to the PREM Milk
Bank by 448 donors between 2007 and 2011.
Results: Milk batches donated in hot months contained more bacteria with rejection
criteria such as high bacterial load (≥105 CFU/mL) and the presence of pathogenic
bacteria. 92% of 2890 milk batches had bacteria present. Coagulase negative
Staphylococcus (CNS) was detected most frequently. S. aureus was the most frequent
pathogenic bacteria detected and may also be a toxin producing bacteria.
Conclusion: Pathotoxigenic bacteria can potentially produce enterotoxins that cannot
be detected with conventional culture methods and could potentially injure preterm
infant intestinal tissue. Future research is planned to develop a cell culture based
method to detect toxins in milk.