Pink Bathroom Mold’s Fascinating Religious and Military Ties
Make no mistake, pink mold — once regarded as harmless — is a pathogen. And because of its color, it has a quirky history.
Pink mold, also known by the more derogatory name pink slime, doesn’t get the respect it deserves. Sure, it’s a household nuisance most commonly found in bathrooms. But that can be a plus, as Lina DeSilva, founder of Toronto Shine Cleaning, says.
“What if pink mold serves as a bio-alert, signaling it’s time to focus on our home’s health?” she says.
Good point. Especially since the pigment that gives this “mold” its pink color has historic medical applications.
Once thought to be harmless, pink mold was used as a tracer organism to predict the spread of bacterial infections. The easily detectable color allowed researchers to trace its progress through the systems of living organisms, including people.
Pink mold looks pink on your bathroom walls, but it turns blood-red when it grows in bread. It may not be as dangerous as black mold. But it isn’t something you want in your bathroom, or anywhere else.
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What Is Pink Mold?
It turns out pink mold isn’t mold at all. Mold is a type of fungus, and pink mold is a species of bacterium with the scientific name Serratia marcescens.
Unlike most other bacteria, this one is pigmented. The pigment, known as prodigiosin, appears vivid red in a full-blown colony. When a colony grows on bathroom surfaces, the film it creates is usually thin, which is why it appears pink instead of red.
S. marcescens is common and establishes colonies in soil, saline and fresh water, and plants, animals and humans. Scientists believed it was a species of mold until the mid-twentieth century. When they finally realized it was a bacterium, they conferred the name given to it by Bartolomeo Bizio, the Italian researcher who studied it in the early 1800s.
Bizio, who grew colonies in polenta, thought it was a fungus. Oddly, he named it after Sarafino Serrati, an Italian physicist who pioneered work with steamboats.
Pink Mold Sparked a Religious Feast Day
The ability of S. marcescens to grow in damp bread and turn blood-red was responsible for a number of minor “miracles” in ancient times. Perhaps the most notable such “miracle” occurred in 1263 A.D. during Mass at the Church of Saint Christina in Bolsena, Italy.
A Bohemian priest named Peter of Prague, who doubted the doctrine of the transubstantiation — whereby the bread and wine offered during Mass turns into the body and blood of Christ — was raising bread as an offering when it began to drip a blood-like liquid. This was considered so significant that Pope Urban IV instituted the Feast of Corpus Christi the following year. Catholics have celebrated it ever since.
The altar cloth where the “blood” dripped — the Corporal of Bolsena — is preserved and venerated at a cathedral in Orvieto, Italy. The Renaissance artist Raphael painted a fresco to depict the event, which still adorns the Apostolic Palace in the Vatican.
Pink Mold as a Tracer Organism
The vivid coloration makes S. marcescens a useful tracer organism. If someone inhales or ingests it, researchers can detect it in that person’s blood and organs. This inspired a covert operation called Operation Sea Spray conducted by the U.S. military in 1950, to gauge the vulnerability of the population to biochemical attacks.
A minesweeper sprayed bacteria into the atmosphere two miles off the coast of San Francisco for six days, then took samples at 43 sites to determine how far it had spread. They found widespread evidence of infection.
At the time, the military believed that S. marcescens was harmless. But one week after the test, 11 people showed up at Stanford University Hospital complaining of urinary tract infections. Today, medical professionals warn this is a common effect of inhaling the bacteria, now considered a pathogen.
Is Pink Mold Dangerous?
Yes. DeSilva calls S. marcescens “the chameleon of household nuisances.” It can be responsible for a number of diseases, including conjunctivitis, pneumonia and meningitis.
Multiple sources confirm only a small percentage of people are adversely affected by a Serratia infection. They include the elderly, the very young and those with pre-existing conditions. Those susceptible seldom eliminate the bacteria from their systems entirely, so the ill effects become chronic.
Even more concerning, Serratia belongs to a group of bacteria that release enzymes to protect them from antibiotics. Those enzymes can reduce the efficacy of antibiotics on other bacteria.
How To Get Rid of Pink Mold
The Centers for Disease Control and Prevention (CDC) recommends cleaning pink mold with soap and water. Various online sources suggest a cleaning paste of a half cup of baking soda and one tablespoon of dishwashing liquid.
“The best way to handle it?” asks DeSilva. “Deep cleaning followed by regular maintenance.”
So if you see it growing, it’s time for a deep clean, But if you stick to a regular cleaning routine, things should never get to that point.