Characterisation of a novel SCCmec VI element harbouring fusC in an emerging Staphylococcus aureus strain from the Arabian Gulf region

Abstract

Fusidic acid is a steroid antibiotic known since the 1960s. It is frequently used in topical preparations, i.e., ointments, for the treatment of skin and soft tissue infections caused by Staphylococcus aureus. There is an increasing number of methicillin-resistant S. aureus (MRSA) strains that harbour plasmid-borne fusB/far1 or fusC that is localised on SCC elements. In this study we examined a series of related CC30-MRSA isolates from the Arabian Gulf countries that presented with SCCmec elements and fusC, including a variant that—to the best of our knowledge—has not yet formally been described. It consisted of a class B mec complex and ccrA/B-4 genes. The fusidic acid resistance gene fusC was present, but contrary to the previously sequenced element of HDE288, it was not accompanied by tirS. This element was identified in CC30 MRSA from Kuwait, Saudi Arabia and the United Arab Emirates that usually also harbour the Panton-Valentin leukocidin (PVL) genes. It was also identified in CC8 and ST834 isolates. In addition, further CC30 MRSA strains with other SCCmec VI elements harbouring fusC were found to circulate in the Arabian Gulf region. It can be assumed that MRSA strains with SCCmec elements that include fusC have a selective advantage in both hospital and community settings warranting a review of the use of topical antibiotics and indicating the necessity of reducing over-the-counter sale of antibiotics, including fusidic acid, without prescription.

Genotyping of methicillin resistant Staphylococcus aureus from the United Arab Emirates

“…In accordance with reports from other parts of the world, community associated MRSA (CA-MRSA) lineages have overtaken HA-MRSA lineages as aetiological agents also of nosocomial infections. Interestingly, MRSA isolates circulating in the region represent a wide clonal diversity 3 , 8 , 10 – 12 . Furthermore, emergence of novel and variant MRSA strains including those with novel SCC mec elements or with complex elements that include mecA as well as a gene associated with fusidic acid resistance ( fusC ) continue to be reported 3 , 8 , 10 .…”

Characterisation of S. aureus/MRSA CC1153 and review of mobile genetic elements carrying the fusidic acid resistance gene fusC

“…As previously discussed 30 , fus C was detected in as much as twenty-two different clonal complexes of S. aureus, CC1, CC5, CC6, CC7, CC8, CC15, CC22, CC30, CC45 [ agr I], CC45 [ agr IV], CC50, CC59, ST72, CC88, CC97, CC121, CC152, CC361, CC779, ST834, CC913 and CC1153 from essentially all parts of the world. This and the emergence of fus C-MRSA especially in the Middle East indicate a selective advantage associated with its presence.…”

“…Its fusC gene has one characteristic SNP (309G > A). It was not yet found in MSSA, but in MRSA belonging to CC8, CC30 and ST834 30 . In these strains, it is accompanied by a mec complex B and a set of ccrA/B-4 genes.…”

“…Please note that this is an abridged version; for a more detailed version, see Supplement 5 . References 28 , 30 , 32 , 34 . **Split across two or more contigs so that the correct order of SCC elements and/or individual genes cannot be determined.…”

“…It can be found in MSSA, such as the prototypical CC1-MSSA sequence Sanger MSSA476, as well as in MRSA. It appears in MRSA strains (CC1 and CC5) with SCC mec IV elements, mainly form the Middle East 25 , 28 , 30 , 31 , Australia and New Zealand 38 as well as in SCC mec V strains from the Middle East.…”