Modelling the impact of antibiotic use and infection control practices on the incidence of hospital-acquired methicillin-resistant Staphylococcus aureus: a time-series analysis.
OBJECTIVE
Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. A wide range of factors have been suggested to influence the spread of MRSA. The objective of this study was to evaluate the effect of antimicrobial drug use and infection control practices on nosocomial MRSA incidence in a 426-bed general teaching hospital in Northern Ireland.


METHODS
The present research involved the retrospective collection of monthly data on the usage of antibiotics and on infection control practices within the hospital over a 5 year period (January 2000-December 2004). A multivariate ARIMA (time-series analysis) model was built to relate MRSA incidence with antibiotic use and infection control practices.


RESULTS
Analysis of the 5 year data set showed that temporal variations in MRSA incidence followed temporal variations in the use of fluoroquinolones, third-generation cephalosporins, macrolides and amoxicillin/clavulanic acid (coefficients = 0.005, 0.03, 0.002 and 0.003, respectively, with various time lags). Temporal relationships were also observed between MRSA incidence and infection control practices, i.e. the number of patients actively screened for MRSA (coefficient = -0.007), the use of alcohol-impregnated wipes (coefficient = -0.0003) and the bulk orders of alcohol-based handrub (coefficients = -0.04 and -0.08), with increased infection control activity being associated with decreased MRSA incidence, and between MRSA incidence and the number of new patients admitted with MRSA (coefficient = 0.22). The model explained 78.4% of the variance in the monthly incidence of MRSA.


CONCLUSIONS
The results of this study confirm the value of infection control policies as well as suggest the usefulness of restricting the use of certain antimicrobial classes to control MRSA.
Aldeyab
Mamoon A
MA
Clinical and Practice Research Group, School of Pharmacy, Queen's University Belfast, BT9 7BL Belfast, Northern Ireland, UK.
Monnet
Dominique L
DL
López-Lozano
José María
JM
Hughes
Carmel M
CM
Scott
Michael G
MG
Kearney
Mary P
MP
Magee
Fidelma A
FA
McElnay
James C
JC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology* / Q000517:prevention & control; D004363:Drug Utilization / Q000706:statistics & numerical data; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D015994:Incidence; D007223:Infant; D017053:Infection Control / Q000379:methods*; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D015999:Multivariate Analysis; D009660:Northern Ireland; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology* / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013223:Statistics as Topic; D013997:Time Factors
D000900:Anti-Bacterial Agents