Who is tougher? MRSA, MSSA or VISA?

Who is tougher? MRSA, MSSA or VISA?

There is a general feeling that being antibiotic resistant imposes a considerable fitness cost for bacteria - and the more resistant, the less fit the bacterium becomes. Whilst this is no-doubt true to some degree, a recent study from Brazil shows that MRSA, MSSA and vancomycin-intermediate S. aureus (VISA) have very similar survival properties on dry surfaces.

Staph

One strain of MRSA, MSSA and VISA were dried onto various surfaces and survived for a similar length of time. In general, S. aureus survive better on non-porous surfaces than on porous surfaces - and VISA 'out-survived' the MRSA and MSSA strain on the non-porous surfaces. However, VISA didn't do so well on the porous surfaces, surviving for less time than MRSA and MSSA. Previous studies have suggested that VISA are better at forming biofilms than other S. aureus. This was tested, but did not seem to be the case ' the MRSA strain seemed to be the most effective biofilms producer.

However, since only one strain of each type was tested, it is difficult to be certain of any comparisons. Previous work has illustrated considerable strain variation in the survival properties of S. aureus, so it's a shame that more strains were not included for each group. Nonetheless, the study shows that even highly antibiotic-resistant S. aureus retains the ability to produce biofilm and survive on dry surfaces for extended periods.