The spread of a mupirocin-resistant/methicillin-resistant Staphylococcus aureus clone in Kuwait hospitals

High-level mupirocin- and methicillin-resistant Staphylococcus aureus (MRSA ) isolated from five hospitals in Kuwait were studied by pulsed-field gel e lectrophoresis (PFGE) to determine their relatedness to one another and to high-level mupirocin-resistant MRSA isolated previously in a Bums Unit. The genetic location of mupirocin resistance determinant was also determined. All of the isolates were resistant to gentamicin, kanamycin, streptomycin, tetracycline and cadmium, and contained plasmids of 38, 26 and 2.8 kb. Two isolates contained additional 4.4-kb plasmids. Transfer experiments demonst rated that the 38-kb plasmid encoded high-level mupirocin resistance and th e 4.4-kb plasmid encoded chloramphenicol resistance. PFGE typing of represe ntative isolates from the five hospitals demonstrated that the majority of them had identical or closely related pulsed-field patterns suggesting that they had a common origin. However, they differed from high-level mupirocin -resistant MRSA isolated previously in the Burns Unit in their resistance a nd pulsed-field patterns. Whereas the majority of the previous isolates wer e susceptible to ciprofloxacin and resistant to trimethoprim and chloramphe nicol, the majority of the current isolates were susceptible to trimethopri m and chloramphenicol, and resistant to ciprofloxacin. Only one of the curr ent isolates had identical pulsed-field pattern to the majority of isolates obtained previously in the Bums Unit. The results suggested that a previou sly dominant clone of high-level mupirocin-resistant MRSA has been replaced in the Burns Unit by a new clone, which also spread in four other hospital s. (C) 2001 Elsevier Science B.V. All rights reserved.