Breast milk expression has become a very common practice. Although it is associated with maternal employment, it is also associated with the desire to make it possible for someone else to feed the infant. Pumping to donate the milk has been an uncommon reason, as has been pumping for a hospitalized infant. The prevalence of breast milk expression was determined by reviewing the data from the 2005 to 2007 Infant Feeding Practices Study II by the Center for Food Safety and Applied Nutrition, of the Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC). Of mothers whose infants were younger than 4½ months, 85% had expressed milk at some time since birth, 43% having done so occasionally and 25% on a regular schedule. The number was higher among first-time mothers and slowly declined as the infant became older ( Figures 21-1 and 21-2 ).
The human milk bank has entered another era. The interest in providing human milk for infants with special needs, especially premature infants, has increased, but the concerns regarding donor milk have also escalated. Regulatory bodies have decreed that donor milk must be pasteurized. Milk banks have recognized the need for donors to be carefully screened and women at high risk for certain infections eliminated from the donor pool.
When there are risks associated with using even a mother’s own milk for a given baby, the risk/benefit ratio is determined. Because of the effects of heating, cooling, freezing, and storing milk, some of the most valued and precious qualities are diminished or destroyed; feeding the milk fresh or at least fresh frozen and not heated preserves most of the constituents. The value of the milk produced by women who deliver prematurely has been discussed in Chapter 15 .
Historical Perspective
When “wet nursing” was the immediate alternative feeding to replace a mother’s own milk, and no safe ways were available to store milk of any species, no human milk banks existed. As pasteurization became available and formulas based on milk from other species increased in popularity, the pool of human milk diminished. “Wet nurses” were increasingly difficult to locate, and often were not safe sources because of wet-nurse lifestyle, risk for infections, and poor nutrition. It had already been clearly demonstrated in the early twentieth century that infants who did not receive their mother’s milk had six times the risk for dying in the first year of life (see Chapter 1 ).
The impetus behind milk banks at the turn of the twentieth century was actually the medical profession’s desire to remove the control of infant feeding from wet nurses and separate the product (human milk) from the producer. Pediatricians, anxious to improve the prognosis for infants deprived of their own mother’s milk for medical and social reasons, developed a means of storing human milk for general use for sick infants. The first milk bank was opened in Vienna in 1900. The first one in the United States was established 10 years later at the Massachusetts Infant Asylum, where wet nurses had been the only sources of human milk. In 1919 the first human milk bank was founded in Germany in Magdeburg by Dr. Marie-Elise Kayser. In 1934, she wrote guidelines that were used throughout Europe for the creation and operation of milk banks.
Early attempts at providing donor milk depended on casual screening of donors for tuberculosis, syphilis, and various acute contagious diseases. There was little research investigating human milk, but the dairy industry was rigorous in its attempt to store and market bovine and other mammalian milks. This technology was applied on a small scale, but other human milk banks appeared after Denny and Talbot created the one in Boston. The American Academy of Pediatrics (AAP) established its first formal guidelines for human milk banks in 1943. Similar guidelines were provided in other countries. After World War II, milk banks were mandated on both sides of the Berlin Wall. In 1959 the Federal Republic of Germany (West Germany) had 24 milk banks, and the German Democratic Republic had 62. The numbers gradually decreased.
As technology advanced in newborn care and in infant nutrition, science replaced nature. The interest in human milk faded, and with it the call for banked human milk, in the 1960s and into the 1970s. Experience in Rochester with short-gut syndrome and malabsorption syndromes, however, resulted in the development of a registry of lactating women, who donated fresh milk when needed. A milk bank was developed with donors providing frozen milk on a regular basis. By 1975, five large commercial milk banks were operating in Britain. Milk banks also sprang up across the United States. The system thrived with the establishment in 1985 of the Human Milk Banking Association of North America (HMBANA). The association not only facilitated communications among banks, but also began to investigate processes, develop uniform policies, and most importantly, provide professional and public education.
The threat of human immunodeficiency virus (HIV) and hepatitis, the return of tuberculosis, and drug abuse have cast a long shadow on milk banks in the United States. This resulted in the closure of all but seven milk banks in North America and five in the United States in the nineties (see Appendix H ). In Europe, milk banking has been key in the nourishment of premature and other high-risk infants. The Sorrento Maternity Hospital has supplied 50,000 L of milk from 10,000 donors in 40 years and provided 700 L a year both locally and across Britain in the nineties. In 1994 the remaining 18 milk banks in unified Germany supplied about 15,000 L.
Many developing countries, especially in Central and South America, are establishing milk banks as part of national efforts to promote breastfeeding. Studies done in nurseries in Guatemala have shown a marked decrease in mortality and morbidity rates by providing every infant with human milk, especially colostrum. The United Nations Children’s Fund (UNICEF) has encouraged and supported such efforts.
The First International Congress on Human Milk Banking: A Vision of the Future was held in Brazil in 2000, sponsored by the Brazilian Association of Milk Banks. There are 154 milk banks in Brazil. Representatives from South America, France, United Kingdom, North America, and the Caribbean attended. All of the milk banks processed the milk. Some screened the serum of donors, but not all. None paid donors but some did provide pumps. Regulations vary by locale. A resurgence of milk banks in the United States has occurred in the last 10 years, stimulated in part by the recognition of the value of human milk for premature and especially very-low-birth-weight infants by neonatologists. Another stimulus was the establishment of a for-profit milk bank in California, approved and licensed by the State of California. This milk bank, supported by venture capitalists, studied the safest ways to process milk. The milk bank was able to measure the caloric value of the milk and provide milk of 20, 22, 24, and 28 cal/oz. Its most important contribution has been the development of a supplement consisting only of human milk to be used to enhance the protein, calcium, and caloric content of a feeding of mother’s milk for a premature or other compromised infant who requires extra calories, protein, and minerals.
Storing Human Milk
It is often necessary to store milk for infants, especially in the hospital. The storage of human milk involves two types of milk: mother’s milk and donor milk. The distinction becomes important in how the milk is stored and prepared for an infant. It is also important because many states have developed codes for donor milk but fortunately have not regulated mother’s milk as yet. Certain guidelines are appropriate for each milk. Indications for use of such milk were alluded to in other chapters but are briefly summarized here.
Mother’s Milk for a Healthy Infant
The conditions under which a mother collects and stores milk while at work are not always ideal. At home, at work, or at school, milk should be collected with clean equipment, stored in sterile containers (dishwasher cleaned and dishwasher dried suffices), and handled with just-washed hands. The limits of temperature and time are an important consideration in the storage of milk.
To assess microbial growth and stability of milk protein and lipid at varying temperatures and for varying lengths of time, Hamosh et al. collected samples from 16 healthy women with healthy babies who were exclusively breastfed. Sampling was done early in lactation (1 month postpartum) and late in lactation (5 to 6 months postpartum). The milk pH decreased from 7.02 ± 0.20 to 5.16 ± 0.26 after 24 hours of storage at 38° C (100° F), and significant differences in pH occurred at all temperatures at 24 hours or longer. Proteolysis was minimal at 15° C (59° F) and 25° C (77° F), but became apparent at 38° C (100° F) at 24 hours. Lipolysis was marked in the first 24 hours at all temperatures compared with freshly expressed milk. Bacterial growth or normal flora was minimal at 15° C at 24 hours, low at 25° C at 8 hours, and higher at 38° C by 4 hours.
The authors concluded that storage of human milk is safe at 15° C for 24 hours and 25° C (room temperature) for 4 hours and should not be stored at 38° C. Proteins appear to maintain their structure and function in short-term storage. The marked lipolysis appears to slow bacterial growth at the same time.
Pasteurizing Breast Milk at Home
Many women face the dilemma of discarding milk pumped when they had a Candida infection of the breast before it was diagnosed. Freezing does not destroy Candida . It has been suggested that milk could be “pasteurized” at home, for use at home by the mother’s own infant. Below are the steps for home pasteurization for one’s own infant, not a milk bank:
Pour all milk into a large saucepan, and place over medium heat on the stove.
Using a candy thermometer, gradually bring the milk to a temperature of 145° F (62.5° C).
Watch closely, and stir often, keeping milk at this temperature for 30 minutes.
Milk can then be poured into appropriate storage containers.
Label each container with the baby’s name and the date and time of pasteurization.
Freeze the pasteurized milk in dishwasher-clean containers until ready for use.
Do not boil the milk (boiling occurs at 212° F or 100° C).
If performed correctly, this process will decrease nutritional and immunologic components by about 30%, but will destroy all microorganisms.
See Protocol 8 in Appendix P for more information. This milk should not be shared, but used only for the mother’s baby.
Mother’s Milk for a Sick Infant
The following situations are common scenarios for the use of mother’s own milk.
- 1.
A mother plans to breastfeed the infant ultimately but needs to provide pumped milk until the infant can be put to the breast.
- 2.
An infant requires the special nutritional benefits of human milk (as with those infants who are recovering from intestinal surgery), but cannot nurse at the breast.
- 3.
An infant weighs 1500 g or less and has difficulty digesting and absorbing other milks and is usually fed by nasogastric tube.
Milk Sharing
Milk sharing has become a popular source of human milk, and the various methods have generated much discussion in various media. Serious analysis of the activity has shown that it is not safe. A carefully executed study of milk samples purchased on the Internet showed high contamination with bacteria and, in some cases, pathogenic bacteria. The authors also reported poor collection, storage, and shipping practices. This study did not measure toxins, pharmaceuticals, or medications, which are also a risk in shared milk for the sick or premature infants. Caloric content and protein levels were not measured. Clearly, Internet sharing or selling milk by unscreened donors is not recommended. Small community-based nonprofit milk sharing systems where the donors are screened provide safety. They do not guarantee the caloric content, and it is known that the caloric content can be as low as 15 cal/oz. Neonatal intensive care units (NICUs) who need milk for high-risk infants should only accept milk from certified sources.
Donor Milk From a Milk Bank
The following scenarios are common reasons for obtaining donor milk from a bank.
- 1.
An infant is at risk for infection or necrotizing enterocolitis. Fresh colostrum is held to be especially protective and may be collected from low-risk, carefully screened mothers, who are not breastfeeding their own infants.
- 2.
An infant has a gastrointestinal anomaly or other reasons for intestinal tract surgery, especially short-gut syndrome.
- 3.
A physician thinks an infant would benefit from the nourishment in human milk because of prematurity, especially if the infant weighs less than 1500 g.
- 4.
A mother is temporarily unable to nourish her own breastfed infant completely. It may be that the mother’s supply is inadequate when she first puts the infant to the breast after weeks of pumping, or when the mother has been ill or hospitalized. Usually these infants are already at home.
- 5.
Donor milk is an excellent transition from parenteral nutrition when mother’s milk is not available. It allows earlier weaning from parenteral solution—earlier than when formula is known to be tolerated.
- 6.
Metabolic disorders, especially amino acid disorders, respond well because of the physiologic profile of human milk (decreased casein, tyrosine, and phenylalanine). In addition, human milk is protective against infection, which may be a serious complication of these disorders.
- 7.
An older infant or child has unique feeding difficulties, usually characterized by an inability to tolerate any oral nourishment except human milk (e.g., a child dying of HIV infection).
Structure of a Milk Bank
Most informal and casual milk banks operating in conjunction with a NICU have disappeared. NICUs may provide a deep freeze for storage of a mother’s own milk for use by her infant. They store it for feeding of the infant and do not process it at all except to culture random samples for contamination. Most do not permit “donating” milk to other infants except by private arrangements between the two mothers with a physician’s approval. No feeding is given to an infant in the hospital without a physician’s order. Smaller public milk banks have phased out since state legislation or local medical practice standards have mandated strict surveillance of samples and pasteurization.
A few large, well-established banks operate in the United States and around the world ( Figure 21-3 ). A network of these milk banks meets and shares information through the HMBANA in North America. Copies of the association’s guidelines for milk storage are available for a fee. HMBANA works closely with the FDA concerning FDA regulations for human tissues and fluids. Appendix H provides the guidelines ( Figure 21-4 ).
The Mother’s Milk Bank of the Institute for Medical Research in San Jose, California, was established in 1974. It has a full-time coordinator and a medical director, provides milk for hundreds of infants, and contributes to the fund of knowledge on human milk. Because the milk is provided to patients only by physician’s prescription, it is reimbursable by health insurance carriers of California. Mother’s Milk Bank has developed procedures and policies regarding milk collection, storage, and processing. This was first described in detail by Asquith et al. and documented with an extensive bibliography.
The State of New York passed an amendment to the public health law in 1980, in which it was declared policy that any and all infants requiring human breast milk be assured access to sufficient quantities of wholesome human breast milk, donated by concerned lactating mothers on a continued and systematic basis. New York State has regulations, which have the force of law, governing human milk banks. They address construction, medical direction, donor qualifications, milk collection and storage, maintenance of records, and milk distribution. They are available on the Internet in Part 52, Subpart 52-9, of Title 10 (Health) of the New York Code of Rules and Regulations, which can be accessed from the New York State Department of Health’s Public website at http://www.health.ny.gov/regulations/nycrr/title_10 (accessed 30 April 2015).
Neonatologists caution that the cavalier feeding of unsterile unsupplemented breast milk to premature infants may produce iatrogenic problems. Mothers who pump and save milk for their own infants should follow the instructions/guidelines for storing mother’s own milk (see Appendix J, Protocol #8 ).
Qualifications of Donors
A mother who is willing to donate milk should be healthy and fulfill the following qualifications ( Box 21-1 ):
- 1.
Normal pregnancy and delivery
- 2.
Serologically negative for syphilis, hepatitis B surface antigen, cytomegalovirus (CMV), and HIV
- 3.
No infection, acute or chronic (i.e., not at high risk)
- 4.
Not taking medications, smoking, or using excessive alcohol
- 5.
Capable of carrying out sterile technique
- 6.
If donating for other infants, own child is healthy and without jaundice
- 1.
Donors answer questions on a verbal health history screening form. Primary health care providers for the prospective donor and her infant are asked for verification of health.
- 2.
Donors are tested serologically for:
- a.
HIV-1 and HIV-2
- b.
HTLV-I and HTLV-II
- c.
Hepatitis B
- d.
Hepatitis C
- e.
Syphilis
- a.
- 3.
Repeat donors are treated as new donors with each pregnancy.
- 4.
Milk banks will cover the cost of the serologic screening if the tests are done by the milk bank.
Reasons for excluding a donor
- •
Receipt of a blood transfusion or blood products within last 12 months
- •
Receipt of an organ or tissue transplant within last 12 months
- •
Regular use of more than 2 oz of hard liquor or its equivalent in a 24-hour period
- •
Regular use of over-the-counter medications or systemic prescriptions (replacement hormones and some birth control hormones acceptable)
- •
Use of megadose vitamins or pharmacologically active herbal preparations
- •
Total vegetarians (vegans) who do not supplement their diet with vitamins
- •
Use of illegal drugs
- •
Use of tobacco products
- •
Silicone breast implants
- •
History of hepatitis, systemic disorders of any kind, or chronic infections (e.g., HIV, HTLV, TB)
When a directive from the Department of Health and Social Security in Great Britain mandated HIV testing for donors to milk banks, it was observed that the list of 19 established milk banks dwindled to six. The Sorrento Maternity Hospital, however, in accordance with the directive of the Department of Health and Social Security, screened all donors for HIV antibodies. Only four mothers of 470 potential donors have refused to be tested, contrary to fears that the ruling would discourage donating.
The donor should not be taking medications regularly, including certain oral contraceptives and any nonprescription medications, such as aspirin or acetaminophen. Her infant should be well and should not have had neonatal jaundice. If the mother is donating only for her own infant, the state of the infant’s health does not prevent her from donating. Any time the donor becomes ill, however, she should discard milk from the previous 24-hour period and not save milk until the illness is ended if the milk is to be donated.
Discarding milk during maternal illness is the most difficult regulation to which a mother must adhere. The desire to contribute may overshadow the mother’s understanding of the risk it poses for an infant who is not her own receiving such milk.
The one limiting factor in donating milk is that the woman must be lactating. Becoming a professional donor of milk today is highly unlikely. The amount of protein has been noted to be lower after 6 months of lactation in some women; thus after 6 months or, at most, 8 months postpartum it is advisable to evaluate a given mother’s contributions to confirm that protein and caloric content is sufficient. There is always the theoretical risk for a donor mixing her collections with cow milk. Milk can be tested for bovine protein. Prolacta Bioscience and Medolac, for-profit milk banks, can screen for a mother’s DNA. These two milk banks screen all donations to confirm a match to the certified donor’s DNA.
Technique for Collection
Whether collecting for a mother’s own infant or for other uses, it is of prime importance to maintain cleanliness and minimize bacteria in the process of collection. The mother should be instructed in washing her hands and her breasts before handling the equipment or pumping.
The two major ways of collecting are letting the milk drip while the infant nurses on the other side, and pumping or manually expressing the milk. Drip milk is acceptable for one’s own infant when it is used as an occasional tide-over feeding in the mother’s temporary absence; however, it is not appropriate for donor milk. Dripped milk has been found to have lower caloric value, lower fat, and a much higher incidence of contamination. Pumped milk has a higher fat content than dripped or manually expressed milk, and in most individuals the volume is also greater. Any equipment used, such as hand pumps, tubing, and collecting bottles, should be sterile. When an electric pump is used, the parts that come in contact with the milk should be sterile or disposable ( Figure 21-5 ). Many hospitals own electric pumps, or one may be rented from a local medical equipment rental company. Some women can pump large volumes of fat-rich milk manually, and for them, manual expression would be acceptable.
The hospital or the bank should provide a program of education for the donors. Milk samples should be cultured initially to ensure proper technique and the absence of significant contamination. Then samples should be sent for culture on a random basis. Studies have shown that milk collected at home has a higher contamination rate than that collected while the same donor is hospitalized, or with equipment maintained by the hospital. Collection at the hospital also avoids the transportation problem.
Many hospitals use the 4-oz sterile water-nursing bottles packaged by formula companies for collections by discarding the water at the time of collection and then filling them with milk. This can be costly if the hospital is paying for feeding supplies. Other programs suggest the use of 50-mL plastic centrifuge tubes, which are pre-sterilized and have tight-fitting tops. These tubes have the advantage of more appropriate volume and easy measurability and sterility. Ideally the hospital or milk bank provides a uniform container. Soft plastic bags are not recommended; however, pump companies sell bags that are safe. If a woman wants to donate a large amount of previously collected and frozen milk that suddenly becomes available (the infant weans or dies), then this milk is a valuable resource. It can be handled separately with culturing and pasteurization, if the milk bank has a protocol for accepting such milk.
The efficacy of various methods of removing milk from the breast has been evaluated. Electric pumping was clearly more effective in raising the maternal prolactin levels and increasing the volume of milk when compared with hand pumping and manual expression. The study did not compare various brands of pumps but types of pumps. A hospital may own a breast pump that is 10 or 20 years old, however, which may not have safety features that are built into current models. Problems of contamination are a significant issue because old models may not protect against milk backing up into the motor or tubing, normally thought to be free of milk, and of potential contamination. Care must be taken to check each machine and follow directions for its proper use. Old vacuum extraction pumps should be discarded.
The use of most of the modern electric pumps with their disposable tubing and collecting vessels makes mechanical pumping the most efficient and cleanest of the methods. In addition, the milking action of an electric pump produces more physiologic stimulus to the breast. Most electric pumps provide attachments for pumping both breasts simultaneously. With double pumping, overall production may be increased, and time for pumping may be cut in half.
Bank milk collected by manual expression is less likely to be contaminated than that collected by hand pumps, even when pumps are boiled or placed in an electric dishwasher. The rubber bulb of the hand pump, resembling a bicycle horn, retains milk and bacteria and should not be used. “Nesty cups,” which are placed inside the brassiere to collect milk drippings between feedings, have been associated with the greatest contamination and are not recommended. Some women develop mastitis using small hand pumps.
Donowitz et al. reported contaminated breast milk as the source of Klebsiella bacteremia in a NICU. Unpasteurized human milk from a single donor fed through nasogastric and nasoduodenal tubes to sick newborns was found to be contaminated from the safety overflow bottle and tubing of the electric breast pump maintained in the NICU. This part of the tubing and equipment should be sterilized or disposed of between collections, according to the manufacturer’s instructions. Strict attention to sterilization of equipment is imperative. Older electric pumps that do not have a built-in mechanism to prevent milk from getting into the permanent “works” should be discarded. Only pumps with disposable or cleanable parts and a safety valve should be used.
The bacteriologic benefit to discarding the first 5 to 10 mL of milk pumped from the breast remains disputed. Some banks require that their donors follow instructions for discarding the first 5 to 10 mL of milk expressed at each pumping and each breast. When a donor is collecting for long-term storage, this may be appropriate. When a mother is collecting for her own baby and her volume is meager, discarding 10 mL may be counterproductive. This is particularly important initially, when early colostrum and milk are less in total volume but high in value to the infant. At home, later, when production is abundant and technique may be less stringent, discarding 2 to 3 mL might be appropriate. This will allow a clean collection without washing the breast before pumping, which is associated with sore nipples in some women.
Collection and Storage Containers
Colostrum was reported by Goldblum et al. to impart greater stability to its components than did mature milk. None of the cellular or humoral immunologic factors investigated were diminished when colostrum was stored at 4° C (39° F) for 24 hours in any of the containers ( Table 21-1 ).
| Constituent | Pyrex | Polypropylene | Polyethylene Bags | Polyethylene (Rigid) |
|---|---|---|---|---|
| Colostrum | Constituents stable | when refrigerated | 24 hours | in all containers |
| Mature milk | ||||
| Cells | Stick to glass | Maintain phagocytosis | Stable | Stable |
| Fat-soluble vitamins | No effect | No effect | – | – |
| Micronutrients | No effect | No effect | – | – |
| Secretory IgA | – | – | Lower | Stable |
| Difficult to handle | – | – | Very | – |
| Spill easily | ||||
| Recommend for donor milk | Highly | No | No | Yes |
The effect of the container on the stability of the constituents of milk was investigated by Garza et al. Pyrex and polypropylene containers were found not to interact with water-soluble and fat-soluble nutrients such as vitamin A, zinc, iron, copper, sodium, and protein nitrogen. Polyethylene bags were found to spill easily, to be harder for mothers to fill without contamination, and to be difficult to handle in the nursery. The containers also leaked and punctured easily, resulting in 60% lower secretory immunoglobulin A (IgA) levels because of adherence to the material. It appears that rigid polypropylene plastic containers may have a significant advantage in maintaining the stability of all constituents in human milk collections and may be easier and safer to handle.
Paxson and Cress have reported a significant difference in the survival of leukocytes when milk is collected and stored in plastic containers rather than glass, because the cells apparently stick to the glass. The phagocytosis of these cells, however, is not affected by the container. The researchers further demonstrated that varying the osmolarity or protein concentration does not alter the number or the phagocytosis of the cells. Because they believe the main reason for feeding preterm infants human milk is for the protection against infection, they suggest nasogastric feedings instead of nasojejunal feeding (to maintain pH in the acid range; in the small bowel, the pH is 6.5 to 8). The milk is collected in sterile plastic containers and maintained in the refrigerator until it is fed to the infant, avoiding heating, freezing, and alkaline solutions (see Table 21-1 ).
Storage and Testing of Milk Samples
Fresh, refrigerated, unsterilized mother’s milk can be used for 48 hours following collection. If the milk is to be used fresh chilled, it should be refrigerated at home and brought in promptly for use within 48 hours. If it is to be frozen, this should be done immediately at − 18° C (0° F) (standard home freezer) or in the top of a refrigerator freezer. The milk stored in the latter should be deep frozen within 24 hours if it is to be stored any length of time. The milk kept at − 18° C can be kept for 6 months. Freezing and thawing, which can occur in a freezer that is part of a refrigerator, significantly alters the energy content and predisposes the milk to separation of the fat layer. Therefore, milk stored in the freezer compartment of a refrigerator freezer with separate doors should be placed well back in the freezer (not in door) and stored for only 1 month. In the hospital or at a bank, all samples should be labeled with name of donor, date, and time of collection. Milk is stored in the freezer in such a way that the oldest milk is used first, and all milk of a single donor is kept together and used only for the infant of that mother.
When a hospitalized mother is contributing fresh milk to her own infant, it is usually not cultured. Pumping is usually done with the help of the nursing staff. Colostrum seems to be more resistant to contamination. Once a mother has been discharged home and she is producing mature milk, however, random sample culturing of her milk samples every week or two is a mechanism for checking milk-expression technique. NICUs have found that random testing improves technique in general.
Because using the fresh milk from the mother to feed a premature infant is becoming commonplace, it is important to be aware of the bacteria cultured from fresh samples during refrigeration. Samples pumped by hand pump and manually expressed were cultured at zero time and after 48 and 120 hours of refrigeration by Sosa and Barness. Although 8 of 41 samples had no growth, the others had the same bacteria on skin and nipple as appeared in the milk ( Table 21-2 ). Concentration was low and decreased over time ( Table 21-3 ), which is attributed to the bacterial inhibitory factors present in milk. This suggests that refrigeration of carefully collected breast milk is a safe method for more than 48 hours. Guidelines for collection and use of mother’s own milk appear in Appendix P, Protocol #8.
| Bacterial Groups * | No. (%) of Cultures | |
|---|---|---|
| Skin and Nipple | Milk | |
| Staphylococcus epidermidis | 77 (94) | 29 (71) |
| Streptococcus | 17 (21) | 6 (15) |
| Propionibacterium | 10 (12) | 5 (12) |
| Staphylococcus aureus | 4 (5) | – |
| Pseudomonas aeruginosa | 2 (2) | – |
| Klebsiella pneumoniae | 1 (1) | 2 (5) |
* Two or more organisms were identified in several skin, nipple, and milk cultures.
| Cultures | Time of Refrigeration (h) | ||
|---|---|---|---|
| 0 | 48 | 120 | |
| Positive | 33 | 27 | 11 |
| Negative | 8 | 14 | 30 |
| Total | 41 | 41 | 41 |
Standards for Raw Donor Milk
Labeling donor milk immediately on arrival at the bank is mandatory. Bar coding is the most accurate method and is done by Prolacta and Medolac. Hospitals have also adopted the methodology. Centralized breast milk handling and barcode scanning improved safety and reduced breast milk administration errors at Orange County Childrens hospital. Errors were reduced to zero.
The FDA and the CDC do not recommend use of donor milk without heat treatment. Rare children, however, require fresh donor milk and cannot tolerate the heat-treated product. For these infants, the guidelines should be carefully followed. These special donors must be meticulously screened and monitored for high-risk behaviors. Parents of the infant recipient should sign an informed consent form.
All raw donor milk should be screened microbiologically before use. No generally accepted microbiologic criteria exist for such milk, except that no potential pathogens should be present. Such pathogens include Staphylococcus aureus , β-hemolytic streptococci, Pseudomonas species, Proteus species, and Streptococcus faecalis . Some milk that cannot be fed raw can be pasteurized.
Other guidelines for raw donor milk include the following :
- 1.
Each pool of milk shall have a sterile sample taken for bacteriologic screening.
- 2.
Only milk from a specially certified donor with less than 10 4 colony-forming units per milliliter (CFU/mL) of normal skin flora (e.g., coagulase negative staphylococcus, diphtheroids, Staphylococcus epidermis , or Streptococcus viridans ) will be acceptable to dispense raw. The presence of any pathogen is unacceptable.
Standards for Pasteurization of Donor Milk
Milk suitable for pasteurization should meet the following minimum standards :
- 1.
A total aerobic count that does not exceed 1 × 10 6 CFU/mL.
- 2.
S. aureus that does not exceed 1 × 10 3 CFU/mL; risk for feeding heat-treated enterotoxins when S. aureus exceeds 1 × 10 6 CFU/mL.
- 3.
Presence of organisms defined as being of fecal origin does not exceed 1 × 10 4 CFU/mL.
- 4.
Presence of organisms not part of normal flora does not exceed 1 × 10 7 CFU/mL.
- 5.
Presence of no unusual organisms such as Pseudomonas aeruginosa , spore-bearing aerobes, or spore-bearing anaerobes.
Heat Treatment
When human milk was pasteurized at 73° C (163° F) for 30 minutes, minimal immunoglobulins A and G (IgA, IgG), lactoferrin, lysozyme, and C3 complement remained. When the temperature was kept at 62.5° C (144.5° F) for 30 minutes, there was a loss of 23.7% of the lysozyme, 56.8% of the lactoferrin, and 34% of the IgG, but no loss of IgA, according to work done by Evans et al. Similar studies of heat treatments of graded severity were carried out by Ford et al. The findings were similar. Pasteurization at 62° C for 30 minutes (Holder method) reduced IgA by 20% and destroyed IgM and lactoferrin. Lysozyme was stable at 62.5° C but destroyed at 100° C, as was lactoperoxidase and the ability to bind folic acid against bacterial uptake. Growth of Escherichia coli increased when introduced into heated milk. Vitamin B 12 -binding capacity declined progressively with increasing temperature of the heat treatment.
The effects of the Holder method on antiinfective agents were reviewed by Orloff et al., who concluded that high temperatures destroyed much of the bacteriostatic effect of human milk, thus decreasing the benefit to infants. These data raise the question of whether any heat treatment might not increase the risk for enteric infection in infants.
The alterations of the lymphocyte and antibody content after processing were of concern. Significant changes with heat, including a decrease in total lymphocyte count and in specific antibody titer to E. coli , are noted.
Welsh and May discuss antiinfective properties of breast milk and provide two tables to demonstrate the stability of the antibacterial and antiviral properties of human milk.
Low-temperature short-time pasteurization of human milk was reported by Wills et al. using the Oxford human milk pasteurizer. Heating at 56.0° C for 15 minutes destroyed more than 99% of the inoculated organisms, which included E. coli , S. aureus , and group B β-hemolytic streptococci. The remaining activity of antimicrobial proteins after different time/temperature treatments is shown in Tables 21-4 and 21-5 .
| Microbial Analysis of Frozen and Thawed Breast Milk | Vitamin Analysis of Frozen and Thawed Breast Milk | ||
|---|---|---|---|
| Conditions | CFU/mL | Vitamin A (IE/100 mL) | Vitamin C (mg/100 mL) |
| 8° C for 4 hours | 8.6 × 10 1 | 100 | 2.2 |
| 8° C for 24 hours | 3.5 × 10 1 | 100 | 1.7 |
| 23° C for 4 hours | 1.0 × 10 2 | 105 | 1.6 |
| 23° C for 8 hours | 3.7 × 10 2 | 100 | 1.0 |
| Repeated freeze-thaw | 1.1 × 10 2 | 100 | 1.5 |
| Control | 1.1 × 10 2 | 100 | 2.2 |
| Fatty Acid | Highest Peaks | Lowest Peaks | ||||
|---|---|---|---|---|---|---|
| C6 | F | C | D | B | E | A |
| C8 | F | C | D | B | E | A |
| Cl0 | F | D | C | E | B | A |
| C12 | C | D | F | B | E | A |
| C14 | C | D | F | B | E | A |
| C16:1 | C | F | B | D | A | E |
| C16 | C | D | F | B | A | E |
| C18:2 | C | B | F | D | A | E |
| C18:1 | C | F | B | D | A | E |
Bacteriologic screening of donor human milk before and after Holder pasteurization was done at the Mother’s Milk Bank at Austin, Texas. 810 samples from 219 certified donors were used to create 303 pools of pasteurized donor milk. Fourty-four pools of preterm donor milk were also studied. After Holder pasteurization, 93% of the pooled milk samples had no growth on routine cultures. All donor milk with any detectable bacterial growth after pasteurization was discarded. Holder pasteurization was considered by the authors to be an effective means to remove detectable bacteria from samples. Viruses and enveloped bacteria could not be detected by culture.
High-temperature short-time (HTST) pasteurization is a method used in the commercial dairy industry. It is used for large volumes as well as lesser volumes in professional human milk banks. It requires establishing 72° C (87° F) for 15 seconds, which involves greater technical skill than the Holder method. The investigators report that HTST is effective in the elimination of bacteria as well as important pathogenic viruses. A time of 16 seconds is recommended rather than the original 15 seconds. Subsequently, they have demonstrated that HTST preserves the nutrients in human milk.
HTST treatment (72° F or 87° C up to 16 seconds) of human milk inoculated with endogenous bacteria and CMV rendered the milk bacteria free in 5 seconds and CMV-free in 15 seconds. Folic acid and vitamins B 1 , B 2 , B 6 , and C were not affected. Bile salt-stimulated lipase was inactivated by these conditions. Lactoferrin and IgA and secretory IgA antibody activity were stable at 72° C (162° F) for 15 seconds. Lysozyme concentration and enzymatic activity were increased, suggesting that lysozyme may be sequestered in the milk.
The HTST technique was thoroughly studied by Terpstra et al. to determine its effect on the bioburden of human milk. HTST was effective in eliminating all bacteria and lipid-enveloped viruses, as well as at least one nonlipid envelope virus from spiked samples. Furthermore, HTST preserved IgA and other proteins important to immune defences. The authors suggest HTST is the method of choice for milk banks ( Tables 21-6 and 21-7 ).
| Time (s) | ||||||||
|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 3 | 15 | |||||
| <SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | <SPAN role=presentation tabIndex=0 id=MathJax-Element-2-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | <SPAN role=presentation tabIndex=0 id=MathJax-Element-3-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | <SPAN role=presentation tabIndex=0 id=MathJax-Element-4-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | |
| Vitamin B 1 (mcg/mL) | 0.104 ± 0.013 | 9 | ||||||
| 72° C | 0.098 ± 0.005 | 3 | 0.091 ± 0.008 | 3 | 0.088 ± 0.009 | 3 | ||
| 87° C | 0.084 ± 0.011 * | 3 | 0.095 ± 0.027 | 3 | ND | |||
| Vitamin B 2 (mcg/mL) | 0.724 ± 0.132 | 9 | ||||||
| 72° C | 0.75 ± 0.08 | 3 | 0.70 ± 0.09 | 3 | 0.56 ± 0.07 | 3 | ||
| 87° C | 0.66 ± 0.13 † | 3 | 0.72 ± 0.22 | 3 | ND | 3 | ||
| Vitamin B 6 (mcg/mL) | 0.237 ± 0.081 | 9 | ||||||
| 72° C | 0.27 ± 0.05 | 3 | 0.26 ± 0.025 | 3 | 0.22 ± 0.012 | 3 | ||
| 87° C | 0.25 ± 0.07 | 3 | 0.26 ± 0.02 | 3 | ND | |||
| Folic acid (mcg/mL) | 0.106 ± 0.020 | 9 | ||||||
| 72° C | 0.089 ± 0.005 ‡ | 3 * | 0.065 ± 0.018 | 3 | 0.101 ± 0.012 | 3 | ||
| 87° C | 0.088 ± 0.008 | 3 | 0.080 ± 0.023 | 3 | ND | |||
| Vitamin C (mcg/mL) | 9.2 ± 2.4 | 9 | ||||||
| 72° C | 11.2 ± 1.2 | 3 | 21.5 ± 3.0 * | 3 | 8.7 ± 1.7 | 3 | ||
| 87° C | 16.0 ± 4.9 * | 3 | 22.5 ± 13.3 | 3 | ND | |||
| Time (s) | ||||||||
|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 3 | 15 | |||||
| <SPAN role=presentation tabIndex=0 id=MathJax-Element-5-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | <SPAN role=presentation tabIndex=0 id=MathJax-Element-6-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | <SPAN role=presentation tabIndex=0 id=MathJax-Element-7-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | <SPAN role=presentation tabIndex=0 id=MathJax-Element-8-Frame class=MathJax style="POSITION: relative" data-mathml='P=V×I’>?=?×?P=V×I P = V × I | n | |
| Lactoferrin (mg/mL) | 0.67 ± 0.10 | 8 | ||||||
| 72° C | 0.95 ± 0.21 | 2 | 0.58 ± 0.2 | 3 | 0.83 ± 0.05 | 3 | ||
| 87° C | 0.50 ± 0.02 | 3 | 0.50 ± 0.2 | 3 | 0.47 ± 0.17 | 2 | ||
| Lysozyme (mcg/mL) | 15.0 ± 8.7 | 8 | ||||||
| 72° C | 86.0 ± 3.5 * | 2 | 78.0 ± 16.0 | 3 † | 59.0 ± 7.0 * | 3 | ||
| 87° C | 86.0 ± 9.1 * | 3 | 59.0 ± 9.0 | 3 † | 36.0 ± 7.7 | 2 | ||
| Total IgA (mg/mL) | 0.37 ± 0.08 | 8 | ||||||
| 72° C | 0.37 ± 0.07 | 2 | 0.25 ± 0.06 | 3 | 0.3 ± 0.04 | 3 | ||
| 87° C | 0.06 ± 0.04 * | 3 | 0.04 ± 0.02 | 3 † | 0.05 ± 0.03 | 2 | ||
| sIgA Ab (reciprocal titer) | 10.0 ± 4.8 | 7 | ||||||
| 72° C | 10.2 ± 12.4 | 2 | 10.6 ± 4.8 | 2 | 15.0 ± 3.5 | 3 | ||
| 87° C | < 1 | 3 | < 1 | 2 | < 1 | 2 | ||
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