If you’ve noticed a pinkish slime or residue on bathroom surfaces, you’re not alone. This common substance often appears around sinks, shower walls, and bathtubs, and many assume it’s a type of mould.
However, according to content creator Dr Karan Rajan, “If you’ve seen this pink slime lurking in your bathroom, it’s not mould, it’s bacteria… specifically one called Serratia marcescens.” This bacteria thrives in moist, humid environments, making bathrooms an ideal habitat.
To shed light on the nature of this pinkish slime and how best to manage it, we spoke to Dr Jagadish Hiremath, a public health intellectual, who shared valuable insights on this commonly misunderstood household issue.
What Serratia marcescens is, and why it frequently appears as pink slime in bathrooms
“Serratia marcescens is a type of bacteria commonly found in moist environments like bathrooms. It’s recognisable by its pink or reddish hue, which often appears as a slimy film on surfaces such as shower walls, tile grout, and around sinks. This bacterium thrives in damp, humid areas with a constant supply of organic matter, which it feeds on. In bathrooms, sources of organic nutrients may come from soap scum, shampoo residue, and even the oils from our skin, making these surfaces ideal for bacterial growth,” informs Dr Hiremath.
The distinct pink colour results from a pigment called prodigiosin, he adds, which Serratia marcescens produces under certain conditions. “Bathrooms, especially those with inadequate ventilation, create an ideal breeding ground for this bacteria. Research in Applied and Environmental Microbiology highlights that warm, moist environments combined with limited air circulation allow Serratia marcescens to grow and spread, making it a common sight in bathrooms.”
In home bathrooms, the risks are relatively lower (Source: Freepik)
Is exposure to Serratia marcescens harmful?
Dr Hiremath states, “For most healthy individuals, brief exposure to Serratia marcescens is typically low-risk, but the bacteria can pose certain health concerns, particularly for people with compromised immune systems.”
The risks are relatively lower in-home bathrooms, but exposure should still be minimized, especially in households with infants, elderly individuals, or those with weakened immune systems. “Regular exposure to the bacteria through contact with contaminated surfaces or inhaling airborne particles during a shower can lead to skin irritation, mild respiratory symptoms, or, in rare cases, infections. Practicing good hygiene and regularly cleaning surfaces can greatly reduce any health risks associated with Serratia marcescens,” says Dr Hiremath.
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Most effective ways to prevent and remove this bacteria buildup from bathroom surfaces
Here are some effective cleaning strategies, according to Dr Hiremath:
Vinegar and Baking Soda: Create a baking soda and water paste, scrub the affected area, then rinse with vinegar. The chemical reaction helps loosen the bacteria and remove residue.
Bleach Solution: Diluting bleach in water (about 1 part bleach to 10 parts water) is an effective disinfectant. Scrub the affected areas with this solution, then rinse thoroughly.
Hydrogen Peroxide Spray: Hydrogen peroxide has antibacterial properties that can help kill Serratia marcescens. Spray a 3% hydrogen peroxide solution on affected areas, let it sit for a few minutes, then rinse off.
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Keep surfaces dry: Maintaining dry surfaces as much as possible also helps. Serratia marcescens thrive in moisture, so drying surfaces after each use, ensuring proper ventilation, and reducing overall humidity are essential.
