Spontaneous genomic variation in Staphylococcus haemolyticus

The introduction of medical devices and antibiotics in clinical practice have substantially improved quality of life of patient and contributed to extend life expectancy. One of the most cumbersome consequences was the emergence of medical devices associated infections caused by multidrug resistant and opportunistic bacteria like Staphylococcus haemolyticus. However, the reason for its success is still elusive. We found that in the absence of environmental stresses this bacterium has the capacity to produce, spontaneously, sub-populations of genomic and phenotypic variants with deletions/mutations in clinically relevant genes. However, when exposed to an antibiotic pressure, a genomic variant among the population will be recruited and become dominant. We suggest that the maintenance of these subpopulations in different physiological states is an extremely effective strategy to adapt to stresses imposed by the host or the infection environment and might contribute for S. haemolyticus survival and persistence in the hospital environment.