Turning the tide or riding the waves? Impacts of antibiotic stewardship and infection control on MRSA strain dynamics in a Scottish region over 16 years: non-linear time series analysis

Abstract

ObjectivesTo explore temporal associations between planned antibiotic stewardship and infection control interventions and the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA).DesignRetrospective ecological study and time-series analysis integrating typing data from the Scottish MRSA reference laboratory.SettingRegional hospital and primary care in a Scottish Health Board.ParticipantsGeneral adult (N=1 051 993) or intensive care (18 235) admissions and primary care registrations (460 000 inhabitants) between January 1997 and December 2012.InterventionsHand-hygiene campaign; MRSA admission screening; antibiotic stewardship limiting use of macrolides and ‘4Cs’ (cephalosporins, coamoxiclav, clindamycin and fluoroquinolones).Outcome measuresPrevalence density of MRSA clonal complexes CC22, CC30 and CC5/Other in hospital (isolates/1000 occupied bed days, OBDs) and community (isolates/10 000 inhabitant-days).Results67% of all clinical MRSA isolates (10 707/15 947) were typed. Regional MRSA population structure was dominated by hospital epidemic strains CC30, CC22 and CC45. Following declines in overall MRSA prevalence density, CC5 and other strains of community origin became increasingly important. Reductions in use of ‘4Cs’ and macrolides anticipated declines in sublineages with higher levels of associated resistances. In multivariate time-series models (R2=0.63–0.94) introduction of the hand-hygiene campaign, reductions in mean length of stay (when >4 days) and bed occupancy (when >74 to 78%) predicted declines in CC22 and CC30, but not CC5/other strains. Lower importation pressures, expanded MRSA admission screening, and reductions in macrolide and third generation cephalosporin use (thresholds for association: 135–141, and 48–81 defined daily doses/1000 OBDs, respectively) were followed by declines in all clonal complexes. Strain-specific associations with fluoroquinolones and clindamycin reflected resistance phenotypes of clonal complexes.ConclusionsInfection control measures and changes in population antibiotic use were important predictors of MRSA strain dynamics in our region. Strategies to control MRSA should consider thresholds for effects and strain-specific impacts.

Chlorhexidine bathing for the prevention of colonization and infection with multidrug-resistant microorganisms in a hematopoietic stem cell transplantation unit over a 9-year period

“…Restrictions enzymes and parameters used were SMA-I for VRE, SPE-I for P aeruginosa , XBA-I for K pneumoniae , and Apa-I for A baumannii . [24–28] A 1.5% band tolerance and 0.5% optimization were used. Cluster analysis was performed by the unweighted pair group method using arithmetic averages (UPGMA).…”

“…[28,29] The data were aggregated at equal time intervals (months) and we used the autoregressive integrated moving average (ARIMA) model. Therefore, we could evaluate the secular trend (coefficient Beta-1), the immediate change after intervention started (coefficient Beta-2), and the long-term effect of the intervention (coefficient Beta-3).…”

Increasing antibiotic susceptibility inStaphylococcus aureusin Boston, Massachusetts, 2000-2014: an observational study

“…The high prevalence of MRSA infections 9,10 and the increased mortality, cost, and length of hospital stay of individuals infected with MRSA as compared to methicillin susceptible S. aureus (MSSA) 11,12 focused research on describing MRSA epidemiology. In the US and Europe, MRSA incidence peaked in 2005 and has been declining steadily since then 10,[13][14][15][16][17] . While the factors driving the decline in MRSA infections are not fully known, infection control efforts in healthcare facilities appear to have reduced the rates of transmission and infection in colonized individuals [16][17][18] .…”

“…In the US and Europe, MRSA incidence peaked in 2005 and has been declining steadily since then 10,[13][14][15][16][17] . While the factors driving the decline in MRSA infections are not fully known, infection control efforts in healthcare facilities appear to have reduced the rates of transmission and infection in colonized individuals [16][17][18] . Evidence from the UK suggests that intrinsic fitness differences between clonal complexes have resulted in a lineage specific decline, possibly due to alterations in selective pressures from changing antimicrobial use 15,16,[19][20][21][22] .…”

Performance of BD Max StaphSR for Screening of Methicillin-Resistant Staphylococcus aureus Isolates among a Contemporary and Diverse Collection from 146 Institutions Located in Nine U.S. Census Regions: Prevalence of mecA Dropout Mutants

“…Despite variability in the occurrence of CO-MRSA and HA-MRSA invasive diseases, S. aureus persists as the most common organism responsible for human infections, and methicillin resistance remains the most commonly identified resistance in medical institutions (11). Therefore, proper infection control practices and antimicrobial stewardship strategies play important roles in controlling MRSA infections (12,13).…”