Etched aluminium surfaces can reduce hospital-acquired infections

When someone is admitted to hospital, doctors not only have to worry about tackling the illness, but they also have to ensure the person is not infected by fellow patients.

According to the World Health Organisation, out of every 100 hospitalised patients in developing countries, 10 will be affected by at least one hospital-acquired infection (HAI).

Researchers at the Biomaterials and Tissue Engineering Lab of the Indian Institute of Science have developed a method to combat HAIs by giving aluminium surfaces the ability to keep bacteria away and even kill them.

Aluminium foils or sheets are dipped in a solution of sodium hydroxide or potassium hydroxide, creating micro- and nano-scale roughness on the surface. While the micro-scale features prevent the bacteria from attaching themselves to the surface, the nano-scale features act like a bed of pins. When the bacteria try to 'sit' on the sheet, the sharp protrusions rupture their membrane, killing them.

Jafar Hasan, the postdoctoral fellow who led the research, found inspiration for the surface from the wings of insects like cicada and dragonfly, which have similar nanofeatures to kill bacteria.

"We wanted to create a surface which can be used in hospital settings, especially in the intensive care unit. Using these aluminium surfaces in common areas such as on doorknobs, tables and taps would reduce the risk of patients acquiring infections," Hasan said.

E coli, K pneumoniae and  P aeruginosa are the common bacteria responsible for infections in hospital environments. They cause diseases like pneumonia, urinary tract infections and diarrhoea.

The material was put to test at the Mazumdar Shaw Centre for Translational Research of Narayana Hrudayalaya Health City. It was found that the etched aluminium surface killed 97% of E. coli and 28% of the Staphylococcus aureus cells in comparison to 7% and 3%, respectively, on smooth surfaces.

With more strains of bacteria becoming resistant to multiple drugs and even to disinfectants, this method could prove especially useful. "Since this method does not rely on chemicals to kill or repel bacteria, it does not matter if it is resistant to antibiotics," said Kaushik Chatterjee, associate professor and head of the lab.

The method is affordable, easily scalable and does not require much expertise. The team is in talks with clinicians and surgeons in some hospitals in the city.

"We are trying to understand where the surface would be most useful. Is it on doorknobs, headboards of beds or side tables? Once we understand their requirement, we will help them test it out," Chatterjee said.