Read Time | 8 minutes

Case 1

The mother of a premature baby (born at 31 weeks) posted on social media inquiring about her bottle parts turning bright pink. She mentioned that in addition to the pink 'residue' on the bottles, she noticed pink stains on her baby's bibs and onesies after washing and that there was pink milk from an unfinished bottle in her diaper bag. Her 3-month old (7 weeks adjusted) had no signs of illness and showed no changes in behavior.

The day following her initial post, she visited her care provider, who took a sample of her milk for culture. She was advised to continue breastfeeding.

Her milk culture came back for S. Marcescens; she was prescribed antibiotics and continued to breastfeed on the recommendation of her Pediatrician and Lactation consultant.

Case 2

A mother reported noticing her neon pink milk on two occasions. Once when she accidentally left a bottle that had contained her breastmilk in her diaper bag and retrieved it two days later and noted that it had turned pink. She described it as though a "pink highlighter exploded in the bottle." She sterilized the bottles and had no issues with pink milk until the second occurrence.

She observed a similar situation about a month later, which prompted her to call her doctor, who mentioned that he had never seen anything like what she described. After phoning her Lactation consultant, who too admitted they were unfamiliar with the situation, she reassured the mother that as long as her daughter wasn't symptomatic and only occurring occasionally, it was okay to continue to feed her the pumped milk. The lactation consultant suggested getting a milk culture done should the pink milk return.

Case 3

A mother posted in an online forum concerned about neon pink staining on her baby's blankets, clothes, and on her breast pads. She reported that her milk is initially white upon expression but that when it dries, it instantly turns neon pink.

Unsure of the cause of the color changes, cut out all pink and red foods and drink and made an appointment with her care provider and a lactation consultant. Upon inspection, her provider stated that her nipples looked intact with no apparent signs of bleeding or cracking.

Both the doctor and nursing staff had never seen a case of this and were unsure of the cause. Unfortunately, there's no information on how this case resolved.

Case 4

On social media, a mother expressed concerns after observing bottles left out overnight for cleaning, turning fuschia pink. She reported that her eight-week-old was fussy and wanted to nurse constantly, but that she had concerned about feeding him her milk due to the possibility of Serratia Marcescens contamination.

After introducing infant formula due to worries about her milk, she started to notice pink reside in bottles used for infant formula. She concluded that the issue was the water used to clean the bottles, so she returned to breastfeeding, paying extra attention to sanitizing her bottles.

Case 5

A breastfeeding mother of twins contacted her pediatrician after she noticed burp cloths and the top of onesies turning pink. At her appointment, she brought in the burp cloths but was ultimately dismissed as being a non-issue.

Still concerned, she saw a second pediatrician, this time bringing in sterilized, labeled bottles containing both fresh expressed breastmilk and milk that each twin had drunk from (One bottle for each twin). The only bottles that had turned pink were the ones that came in contact with her infant's mouths. Again, the pediatrician dismissed her.

Finally, after getting a third opinion, she was told to put both babies on a probiotic and to continue to sterilize bottles/pump parts. After starting the probiotics, she reported no further instances of neon pink breast milk.

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Though not all cases were confirmed as Serratia Marcescens, each example presented similarities associated with the typical presentation of S. Marcescen colonization of breastmilk.

Typical signs of S. Marcescens colonization include:

Neon/Fuschia pink staining on bibs, burp cloths, clothing, or diapers that occur either after washing or once in the laundry
Milk that is white upon expression but that later turns bright pink after sitting at room temperature

I should note that though this post focuses on breast milk, S Marcescens colonization is not exclusive to breastfeeding parents. There are documented cases of Serratia Marcescens in the formula-fed babies. Additionally, babies may come into contact with S. Marcescens through avenues other than infant feeding.

What is Serratia Marcescens?

S. Marcescens is a common, generally benign, opportunistic bacteria that can be found anywhere from soap dishes to floors both at home or in the hospital setting. A bright pink color often accompanies an S. Marcescens colonization is due prodigiosin a red-orange pigment produced by the bacteria at temperatures lower than 98.6 F.

Serratia Marcescens has a preference for damp conditions, which accounts for its prevalence in bathrooms, kitchens, and washer machines and the pink or orangeish slimy film sometimes left behind in the bathtub.

How does S. Marcescens get into breastmilk?

The mode of transmission varies depending on the location, but the most common way Serratia Marcescens is introduced into expressed breastmilk at home is from the contamination of bottles via bacteria found in the kitchen sink or dishtowels.

S. Marcescens is a pathogen that can be associated with Bovine mastitis, so some reports hypothesize the potential for it to cause mastitis in humans as well. Though there certainly is potential for that to be the case, as of writing this, I've found no confirmed cases of S. Marcescens as the cause of mastitis.

With that said, cultures of human milk have been positive for Serratia Marcescens, so colonization of breastmilk in the breast a potential mode of infection.

What are the risks of S. Marcescens?

As mentioned above, Serratia Marcescens is generally benign but does pose significant risks to medically fragile and premature infants.

Some of the potential risks of S. Marcescens infection include

Feeding intolerance
bloodstream infection (sepsis)
conjunctivitis (eye infections)
pneumonia
urinary tract infection
meningitis

Full-term, healthy babies rarely develop infections from ingesting Serratia Marcescens. Still, some may be asymptomatic or have mild signs such as feeding intolerance and fussiness during feedings (along with pink diapers or dried spit-up).

I think I have Serratia Marcescens, what should I do?

If you suspect you have an S. Marcescens in your breast milk, it can be very alarming and worrisome! The good news is that S. Marcescens infections of infants in the at-home setting are rare.

Its recommended that you see your primary care provider so they can do a milk culture to confirm the type of bacteria and to know if it's resistant to any antibiotics (AST). If your milk tests positive for Serratia Marcescens, you have the option of starting an antibiotic or taking a more conservative approach.

Whether or not your provider feels an antibiotic is necessary will depend on their familiarity with conservative treatment options, your baby's gestation, and whether or not your baby is showing signs of an infection.

Your provider may also culture your baby's stool to see if they are colonized with S. Marcesens. The results of this culture may contribute further to whether or not they feel antibiotics are necessary.

What antibiotics might my doctor prescribe?

The most suitable antibiotics for S. Marcescens appear to be Cefotaxime (Claforan) and Gentamicin(Gentak), both of which are considered compatible with breastfeeding.

Serratia Marcescens showed the highest resistance to Ceftriaxone, Ceftazidime, and Piperacillin and Tazobactam and may be resistant to other antibiotics.

It's for this reason that before any antibiotics are started for suspected cases, an AST is performed.

Do I have to stop breastfeeding?

Regardless of whether or not you choose to utilize antibiotics, direct breastfeeding is typically safe to continue. The small amount of S. Marcescens a full-term, healthy baby would ingest from direct breastfeeding makes the risk low for adverse outcomes.

Pumping and storing milk poses a higher risk as improper storage and handling may allow the bacteria to grow in number, increasing the possibility of infection.

To reduce this risk, ensure you're following safe milk storage, wash your hands and pump parts before and after you express, sterilize pump parts and bottles daily, and keep all of your parts dry.

Overall, S. Marcescens colonization is more alarming than anything else, but getting the appropriate support and care may be a challenge. Not every case of S. Marcescens needs antibiotics, and with the growing concerns of antibiotic resistance, providers may avoid the use of antibiotics in the absence of symptoms. Because other bacteria, such as Pseudomonas, also create a pink pigment, getting a culture done is essential. Breastfeeding rarely needs to be interrupted and usually can continue, though some parents, for fear adverse outcomes, may choose to wean.

If you would like to read more information/case studies on S. Marcescens, please check out the links below. And if you haven't already, follow me over on Facebook! I would love for you to join our growing community!