Amoebe promote persistence of epidemic strains of MRSA

Scientists in the UK have found that a type of amoeba acts as an incubator for MRSA bacteria. As amoebae are often found in healthcare environments this discovery has implications for the infection control strategies adopted by hospitals.

The single cell amoeba, Acanthamoeba polyphagam, commonly eats and digests environmental bacteria. It also engulfs pathogens such as MRSA. However, instead of being digested by the amoeba, MRSA survives and replicates whilst inside the amoeba. Prof Michael Brown and colleagues at the University of Bath, found that MRSA in association with amoebae increased in numbers 1000- fold.

The pathogenic bacteria, Legionella, also replicate inside amoebae and are then released into the environment. The released bacteria are less susceptible to biocides and antimicrobials, and are more invasive than the same bacteria which have grown freely. Replication within amoebae may have the same effect on MRSA.

Amoebae, as cysts, are often dispersed by air currents, providing another means of spreading any trapped bacteria.

“We need more research into the role of amoeba in the spread of MRSA - hospitals should aim to eradicate amoebae as well as the bacteria themselves” said Prof. Brown of the Department of Pharmacy and Pharmacology, University of Bath.