Superbugs and disinfectants

The recent FDA warning about contaminated handwashing liquid in Puerto Rico was a paradox considering that billions of people use handwashing liquid each day to avoid contamination.

Handwashing liquids contain disinfectants, which by definition are substances which hinder growth of even kill bacteria. Disinfectants come in many forms, from handwashing liquids, to gels and soaps. In recent years, however, more and more evidence is accumulating that disinfectants and other germ-killing compounds in our armory are simply losing their potency against superbugs that are so adaptable that they learned how to survive, even thrive in the compounds meant to kill them.

One such superbug is Pseudomonas aeruginosa. Researchers at the University of Ireland in Galway report that this bacterial species can withstand and survive increasing amounts of disinfectants. What is even more cause for concern is the fact that this bacteria is so adaptable that constant exposure to disinfectants enabled it to build up a strong defence mechanism against, not only to the said disinfectants, but even to antibiotics it wasn’t exposed to before.

The researchers report that this disinfectant-resistant species also developed resistance to ciprofloxacin – a commonly-prescribed antibiotic – even without being exposed to it. The resistance developed through a DNA mutation that made them resistant to ciprofloxacin-type antibiotics. In addition, the bacteria have also developed a more efficient system of pumping out antibacterial agents.

P. aeruginosa is an opportunistic bacterial species that may cause mild symptoms in a healthy individual but life-threatening infections in the immunodepressed. Patients with HIV, cystic fibrosis and diabetes are especially susceptible.

Another bug is the notorious Staphylococcus aureus (sometimes called Staph or SA for short), the bug that has evolved into the dreaded MRSA (methicillin-resistant SA). MRSA is responsible for a lot of the so-called nosocomial (hospital-acquired) infections and is resistant not only to disinfectants but to a lot of antibiotics currently available.

These superbugs present a major headache for hospitals and clinics. Disinfection and sterilization is of great importance in these environments. Hospital patients usually have a weakened immune system, are suffering from metabolic problems, or have suffered from major injuries. Exposure of these patients to superbugs can have some severe consequences.

According to Dr. Gerard Fleming, who led the Irish study on P. aeruginosa:

“In principle this means that residue from incorrectly diluted disinfectants left on hospital surfaces could promote the growth of antibiotic-resistant bacteria. What is more worrying is that bacteria seem to be able to adapt to resist antibiotics without even being exposed to them.”

Disinfectants are used to kill bacteria on hospital surfaces and staff to prevent their spread. If the bacteria manage to survive to infect patients, antibiotics are used to fight the infection. However, bugs that that can resist both disinfectants and antibiotics are unbeatable and uncontrollable – and deadly.

It is therefore important to study the environmental factors that might promote antibiotic resistance. Dr. Fleming continues:

“We need to investigate the effects of using more than one type of disinfectant on promoting antibiotic-resistant strains. This will increase the effectiveness of both our first and second lines of defence against hospital-acquired infections.”