**5. Pandemic clones of MRSA samples**

Currently, *Staphylococcus spp*. samples have been typed in numerous epidemiological studies by means of the methods described above. By using these tools, 05 large pandemic clones have been described. These are the Brazilian clone, characterized by *SCCmec* IIIA, MLST 2-3- 1-4-4-3 (ST 239); the Iberian clone with type-IA *SCCmec*, and MLST 3-3-1-1/12-4-4-16 (ST 247); the clone known as New York / Japan, with type-III SCC*mec*, pattern MLST 1-4-1-4-12- 1-10 (ST 05); the Hungarian clone, with SCC*mec III*, MLST 2-3-1-1-4-4-3 (ST 239); the pediatric clone, with type-IV SCC*mec*, MLST 1-4-1-4-12-1-10 (ST 05) and the last large clone known as EMRSA-16, *SCCmec* II MLST 15-12-16-02-16-02-25-17-24-24-24 (ST 36) (Oliveira et al., 2002; Melter et al., 2003; Velásquez-Meza et al. 2004; Aires de Souza & De Lencastre, 2004, Aires Ribeiro et al., 2005).

In our scenario, the predominant MRSA samples belong to the Brazilian clone (Oliveira et al., 2001). The first report on the emergence of this clone dates to 1992-93 in various hospitals in Brazil. The samples were characterized as belonging to the same clone by methods such as PFGE and by showing patterns of transposon *Tn554* and the polymorphism of the *mecA* gene (Teixeira et al., 1995). In other countries, the Brazilian clone is also disseminated, as is the case of the Czech Republic, where the isolation of this clone represented 80% of the MRSA samples found in 1996-1997 (Melter et al., 2003). The Brazilian clone was also described in India, in two hospitals in the region of Bengalore, conjointly with the Hungarian clone (*SCCmec III*) (Arakere et al., 2005)

Other clones are distributed in several parts of the world. The Iberian clone was firstly described in samples from hospitals in Barcelona and Madrid, Spain, and in Lisbon, Portugal. These samples were typed by the PFGE method and probe hybridization, producing a pattern that characterized them as belonging to the same clone. This clone is also described in other countries, such as the Czech Republic (Melter et al., 2003). The clone known as New York – Japan, firstly isolated in the USA in 1994-98 and in Japan in 1997-98 (Oliveira et al., 2002), was also predominant in Mexico during a study on 98 MRSA samples, thus replacing the local clone, known as Mexican (PFGE M, type-IV SCC*mec*), in nosocomial infections (Velasquez-Meza et al., 2004).

The Hungarian clone, firstly identified in Hungary in 1993-94, was characterized by the same methods used for the clones described above in studies on MRSA samples from hospitals in 06 provinces in that country (De Lencastre, 1997). The pediatric clone was isolated in large numbers in 1996-98 in Colombia, and it is also found in Argentina and Poland in 1994-98 and 1990-98 (Oliveira et al., 2002).

The last of the large pandemic clones, referred to as EMRSA-16, is prevalent in hospitals in the United Kingdom, Mexico and Greece, in addition to being responsible for an outbreak in Sweden from 1997 to 2000 (Aires de Souza & De Lencastre, 2004).
