ABSTRACT
Background: implementation of MRSA decolonization programs is increasing and the emergence of mupirocin resistance among MRSA isolates has been a well-defined phenomenon in many parts of the world two mupirocin resistance phenotypes; low-level [LR-Mup] and high-level [HR-Mup] mupirocin resistance. Are defined in staphylococci. High-level mupirocin resistance cannot be eradicated with mupirocin
Aim of the Work: to assess the prevalence of the Mup A [ileS-2] gene encoding high-level mupirocin resistance among MRSA isolates and to study risk factors and predictors of mupirocin resistance in Mansoura University Hospitals [MUHs] supporting an efficient control of MRSA colonization
Materials and Methods: This study was carried out on 1200 nasal swab, MRSA isolates were detected by growth on Mueller-Hinton agar supplemented with 4% NaCl and oxacillin [6mglml] and confirmed by cefoxitin disc 'diffusion test [DDT]. Mupirocin resistance was detected by DDT and agar dilution test [ADT]. The presence of mup A [ileS-2] gene was tested by PCR for all mupirocin resistant MRSA isolates
Results: out of the 396 MRSA isolates, 76 mupirocin resistant strains were detected. Of them 59 [77.6%] were LR-Mup and 17 isolates [22.4%] were HR-Mup Significant risk factors included; previous ICU stay, previous treatment with mupirocin, other antibiotics and previous pseudomonas infection
Conclusion: mupirocin resistance is an emerging problem in MUHs. In our study HR- Mup mupirocin resistance was detected in 22.4% of MRSA isolates. The finding that the ileS2 gene was detected in all HR-Mup MRSA represents an alarming sign as this gene allow the fast spread of resistance among both MRSA, methicillin sensitive S. aureus [MSSA] and coagulase negative staphylococci [CoNS]. Thus we recommend a strict policy on mupirocin use. in MUHs including proper dose and duratio:1 as prolonged use has led to the development of a rapidly transmissible resistance