Takeshi Mikawa1, Katsumi Mizuno2, Kazuo Tanaka3, Chikara Kohda3, Youko Ishii2, Kazuya Yamamoto2, Shunjiro Kobayashi4. 1. Department of Pediatrics, Showa University Koto Toyosu Hospital, Koto, Tokyo, Japan. 2. Department of Pediatrics, Showa University School of Medicine, Shinagawa, Tokyo, Japan. 3. Department of Microbiology, Showa University School of Medicine, Shinagawa, Tokyo, Japan. 4. Bean Stalk Snow Co. Ltd, Research and Development Department, Tokyo, Japan.
Abstract
BACKGROUND: Breast milk (BM) is the best nutrition for very preterm infants (VPI), except when provided by human cytomegalovirus (HCMV)-seropositive mothers. Given that VPI are at high risk of developing a sepsis-like syndrome or cholestasis, methods for prevention of HCMV infection via BM have been investigated. Although Holder pasteurization (HP) is the gold standard, HP needs special instruments. Microwave (MW) is available anywhere, therefore, we performed this study to determine whether MW can be used for HCMV prevention. METHODS: Human cytomegalovirus Towne strain was added to formula, followed by heating procedure using HP or MW (at 500 W for 20, 30, 40, or 60 s). HFL-III cells were seeded in culture dishes. Aliquots of HCMV-milk samples after heating were inoculated onto susceptible cell monolayers. The number of plaques was counted to determine the viral titer. The determination of HCMV-DNA copies was also performed. RESULTS: Addition of HCMV for a viral load of 5.0 × 103 plaque-forming units (p.f.u.)/mL achieved 772 p.f.u./mL at baseline, with a decrease to 257 p.f.u./mL after MW radiation for 20 s. No plaque was detected after HP or MW for 30, 40, and 60 s. The temperature of the breast milk reached 60°C after MW radiation for 40 s. The number of HCMV-DNA copies did not change with MW. CONCLUSIONS: Microwave at 500 W for 40 s can be used as a prevention strategy for HCMV transmission. Further research including the loss of bioactive properties in BM is required prior to clinical application.
BACKGROUND: Breast milk (BM) is the best nutrition for very preterm infants (VPI), except when provided by human cytomegalovirus (HCMV)-seropositive mothers. Given that VPI are at high risk of developing a sepsis-like syndrome or cholestasis, methods for prevention of HCMV infection via BM have been investigated. Although Holder pasteurization (HP) is the gold standard, HP needs special instruments. Microwave (MW) is available anywhere, therefore, we performed this study to determine whether MW can be used for HCMV prevention. METHODS:Human cytomegalovirus Towne strain was added to formula, followed by heating procedure using HP or MW (at 500 W for 20, 30, 40, or 60 s). HFL-III cells were seeded in culture dishes. Aliquots of HCMV-milk samples after heating were inoculated onto susceptible cell monolayers. The number of plaques was counted to determine the viral titer. The determination of HCMV-DNA copies was also performed. RESULTS: Addition of HCMV for a viral load of 5.0 × 103 plaque-forming units (p.f.u.)/mL achieved 772 p.f.u./mL at baseline, with a decrease to 257 p.f.u./mL after MW radiation for 20 s. No plaque was detected after HP or MW for 30, 40, and 60 s. The temperature of the breast milk reached 60°C after MW radiation for 40 s. The number of HCMV-DNA copies did not change with MW. CONCLUSIONS: Microwave at 500 W for 40 s can be used as a prevention strategy for HCMV transmission. Further research including the loss of bioactive properties in BM is required prior to clinical application.