The continued evolution of MRSA is illustrated by the infections caused by CA-MRSA.
While the majority of these infections are non-life-threatening infections of the skin and soft tissues, these organisms are also capable of producing devastating disease in certain patients.
Among other things, their discovery set off a major response from the scientific and medical professions to control or even eliminate them as major human pathogens.
Despite these efforts, however, MRSA have spread throughout the world and a half century after they burst upon the scene they continue to pose major challenges to research scientists and clinicians alike.
It is not clear whether this represents differentiation from a single clone or introduction of SCC speculate, on the basis of multilocus sequence typing with application of the BURST algorithm to an international collection of 912 MRSA and MSSA isolates, that there are 11 major MRSA clones from five groups of related genotypes.
Moreover, their data suggest that methicillin resistance first appeared in sequence type (ST) 250, which likely evolved from an ST8 isolate of MRSA that acquired the Until recently the majority of these clones of MRSA have caused hospital- or healthcare-associated infections [hospital- or healthcare-associated MRSA (HA-MRSA)].
Fossil evidence suggests that staphylococci have existed on earth for more than a billion years, although it was not until the 19th century that they were actually identified as bacterial pathogens.
Nonetheless, it is clear that they have undoubtedly caused serious wound and other infections throughout recorded human history.
Another recent example of this phenomenon is the report of the discovery of phenotypically MRSA from bulk milk in which the In this instance, besides producing resistance to methicillin, the staphylococcus has once again scored a victory in the battle with modern medicine as it has developed a mechanism of methicillin resistance that cannot be detected by the molecular diagnostic tests currently available in the clinical microbiology laboratory.
Pigs have also been implicated as a possible reservoir of MRSA in Europe, where MRSA of ST398 have been isolated from pigs in more than 10 countries.