In our tertiary university hospital, fluoroquinolones were prohibited during 2001 leading to a 90% reduction in their use. Our objective was to examine the trends in meticillin-resistant Staphylococcus aureus (MRSA) following the reintroduction of fluoroquinolones. We conducted a 10-year time-series analysis of monthly MRSA according to: (i) period of fluoroquinolone restriction (January 2001 to January 2002); (ii) period of fluoroquinolone increase up to pre-restriction levels (January 2002 to December 2004); and (iii) an observational period including the implementation of a hand hygiene campaign with alcohol-based hand rub (January 2005 to June 2009). We used segmented linear autoregression analysis to assess trends between adjacent periods. Fluoroquinolone use increased from 5.2 defined daily doses (DDD) per 1000 patient-days in 2001 to 56.6 DDD per 1000 patient-days in 2005 reaching pre-restriction fluoroquinolone levels (P<0.001) and remained stable during 2005e2010 (P=0.65). The monthly proportion of MRSA decreased during the period of FQ restriction (-0.49 per month, P < 0.05). The reintroduction of fluoroquinolones was associated with a significant increase in MRSA (+0.68 per month, P<0.02) compared to the previous period. During period 3, we observed a significant change in MRSA (-5.9, P<0.002) compared to the previous period (-0.32 per month, P<0.001). During the latter period, hand hygiene was promoted and alcohol-based hand-rub consumption increased from 3411 L in 2005 to 14 599 L in 2009. This study reinforces the rationale for a hospital-wide fluoroquinolone formulary policy to control MRSA and suggests that it has an additive effect with a hand hygiene promotion.

• Qualitative data - Qualitative data were used during the intervention

5. Charbonneau P, Parienti JJ, Thibon P, et al. Fluoroquinolone use and methicillin-resistant Staphylococcus aureus isolation rates in hospitalized patients: a quasi experimental study. Clin Infect Dis 2006;42:778e784.

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