S. aureus resistance to methicillin or b-lactam antibiotics is due to modification of 78 kDa penicillin binding protein (PBP)2a encoded by a mec A gene. In 2011, mec C was discovered to be causing resistance to b-lactam antibiotics23. Both mec A and mec C are carried on a large SCCmec element. In addition to mec gene, SCCmec elements also harbours ccr genes, regulatory genes and accessory genes. To date, eleven different types of SCCmec elements have been identified.
This nomenclature is based on the combination of mec complex and ccr complex genes that share similarities. SCCmec types can further be subdivided into subtypes based on variations within joining regions (J-regions) which are classified into subgroups, J1-3. SCCmec elements differ in sizes with SCCmec II (53 kb) and SCCmec III (67 kb) which are frequently linked with HA-MRSA are large and possess Mobile genetic elements (MGEs) while SCCmec IV (24 kb) and SCCmec V are shorter, susceptible to non-b-lactam antibiotics and associated with CA-MRSA.SCCmec elements act as a carrier for exchange of genetic information between different S. aureus strains so as to adapt to different harsh environments and pressures from antibiotic exposures. Therefore, understanding prevalence and occurrence of SCCmec in different hosts and different regions may help in identifying, regulating, preventing and treatment strategies of human diseases caused by S.
aureus.There are few available data regarding the diversity of SCCmec elements in Kenya. Maina et al 2013 conducted a study in a public hospital facility among patients presenting with skin and soft tissue infections in which they found that 75.4% of MRSA were SCCmec type II, 7.2% SCCmec type I and 2.9% had SCCmec IV. Another study from Omuse et al 2016 in healthcare settings found that the predominant SCCmec was type III followed by SCCmec IV.
Contrary to these different types of SCCmec in same study, Aiken et al 2014 conducted a study in a public hospital found that all the six MRSA strains belong to SCCmec type III. The possible reason for single type of SCCmec was because all the MRSA were belonging to the same ST239. It is clear from this information that only SCCmec type I, II, III and IV have been reported in Kenya and all these studies were conducted in clinical settings therefore there is gaps of information of SCCmec occurrence in the community and in the isolates from animals.