Antimicrobial resistance surveillance in Ireland Results of invasive Staphylococcus aureus infection (blood) surveillance, 2009 **** Data as of 01/12/2010 **** Ireland is a member of the European Antimicrobial Resistance Surveillance Network (EARS-Net)

EARS-Net S. aureus: Objective and case definition Objective : To determine the proportions of S. aureus isolates from blood that are resistant to meticillin Case definition: EARS-Net collects data on the first invasive isolate (from blood only) of S. aureus per patient per quarter

Caveats in interpreting EARS-Net data Care must be exercised when interpreting the raw figures, i.e. increases in numbers of isolates, as the numbers of laboratories reporting to EARS-Net has increased over the years EARS-Net data does not distinguish clinically significant isolates from contaminants If MRSA is isolated subsequent to MSSA within the same quarter, then that isolate is not counted (and similarly if MSSA is isolated subsequent to MSSA) [similarly for other pathogen-antibiotic resistance combinations]

For further information on antimicrobial resistance and EARS-Net in Ireland, including quarterly and annual reports, plus reference/resource material on the individual pathogens under surveillance, see: Z/MicrobiologyAntimicrobialResistance/EuropeanAntimic robialResistanceSurveillanceSystemEARSS/

Antibiotic codes and abbreviations: CIP, CiprofloxacinERY, Erythromycin FUS, Fusidic AcidGEN, Gentamicin LIN, LincomycinLNZ, Linezolid MET, Meticillin MUP, Mupirocin OXA, OxacillinPEN, Penicillin RIF, RifampicinTCY, Tetracycline TEI, TeicoplaninVAN, Vancomycin SAU, Staphylococcus aureus MRSA, Meticillin-Resistant S. aureus MSSA, Meticillin-Susceptible S. aureus VISA, Vancomycin-Intermediate S. aureus

Numbers and proportions of S. aureus/MRSA from bacteraemia with 95% confidence Intervals (CI),

S. aureus/MRSA bacteraemia trends, Number of laboratories participating by year-end and quarter are indicated above the bars

S. aureus/MRSA bacteraemia trends by quarter, Number of laboratories participating by year-end indicated above the Q4 bars

S. aureus/MRSA bacteraemia trends, : 4-quarterly moving average Number of laboratories participating by year-end indicated above the Q4 bars

Numbers of S. aureus bacteraemia isolates and %MRSA by Hospital Network, 2009 Dub/M, Dublin Midlands; Dub-N, Dublin North; Dub-S, Dublin South; MW, Mid Western; NE, North Eastern; NW, North Western; S, Southern; SE South Eastern; W/NW, West/North Western

Proportion of S. aureus bacteraemia isolates by Hospital Network, 2009 (n=1309)

Numbers of S. aureus bacteraemia isolates, %MRSA and rates by Hospital Network, 2009 Dub/M, Dublin Midlands; Dub-N, Dublin North; Dub-S, Dublin South; MW, Mid Western; NE, North Eastern; NW, North Western; S, Southern; SE South Eastern; W/NW, West/North Western

Numbers, proportions and rates of MRSA bacteraemia by hospital type, 2009 *Single speciality hospitals; ** Denominator data (BDU, Bed Days Used) not available; *** Complete denominator data not available; ^ includes all private hospitals/quarters for which no activity data were available Note: BDU provided by the Acute Services Team in the Business Intelligence Unit, Corporate Planning and Corporate Performance (CPCP) section of the Health Service Executive for acute hospitals and directly from the infection control/finance departments from private hospitals

Rates of S. aureus bacteraemia isolates by Hospital Network*, 2009 (n=1253) * excludes private hospitals and other non-acute facilities

Rates of MRSA bacteraemia isolates by Hospital Network, 2009 (n=350) * excludes private hospitals and other non-acute facilities

Rates of MSSA bacteraemia isolates by Hospital Network, 2009 (n=903) * excludes private hospitals and other non-acute facilities

Susceptibility data for S. aureus bacteraemia isolates, 2009 (n=1309)

Susceptibility data for MRSA bacteraemia isolates, 2009 (n=355)

Susceptibility data for MSSA bacteraemia isolates, 2009 (n=954)

Antibiogram results for MRSA isolates referred to NMRSARL, 2009 (n=321) Data provided by National MRSA Reference Laboratory, St James’s Hospital

Trends in proportion of gentamicin resistance among MRSA isolates^, ^ Data from National MRSA Reference Laboratory; Changes in the numbers of participating laboratories are indicated above the bars

Trends in proportion of fusidic acid resistance among MRSA isolates^, ^ Data from National MRSA Reference Laboratory; Changes in the numbers of participating laboratories are indicated above the bars

Assume proportion or rate stable over time (i.e. in control) Mean calculated from data for quarters (data points) up to the previous quarter, i.e. excluding latest quarter Warning limits and action limits are equal to 2 and 3 Standard Deviations (SD), respectively These are used to determine if: ◦ the trends in proportions or rates are behaving as expected, i.e. the process is in control. The variation observed here is due to chance (common cause or natural variation) or ◦ the trends are not behaving as expected and something unusual is happening, i.e. the process is out of control. The variation observed here is unlikely to be due to chance alone. Special circumstances are more likely to operate (special cause variation) warranting further investigations Statistical Process Charts

Special cause variation occurs if: One value above or below the action limits (±3SD) 3 consecutive values between upper warning and action limits (or lower limits) 5 consecutive values in top or bottom 2/3 (between 1 and 3 SD, or -1 and -3 SD) 13 consecutive values in top or bottom middle 1/3 (between mean and 1 SD, or mean and -1 SD) 8 consecutive values on the same side of the mean 12 of 14 consecutive values on same side of the mean 8 consecutive values either increasing or decreasing Cyclic or periodic behaviour Statistical Process Charts

Statistical Process Chart National MRSA proportions: P-Chart Mean proportion calculated from data for Q Q3 2009; UWL and LWL, Upper and Lower Warning Limits; UAL and LAL (±2 Standard Deviations), Upper and Lower Action Limits (±3 Standard Deviations)

Statistical Process Chart National MRSA rates: U-Chart Mean rate calculated from data for Q Q3 2009; UWL and LWL, Upper and Lower Warning Limits (±2 Standard Deviations); UAL and LAL, Upper and Lower Action Limits (±3 Standard Deviations)

P-chart: The proportion of MRSA bacteraemia was above its upper control limit in Q2 2002, Q and Q and below its lower control limit for Q and Q2 2008–Q These indicate that the process is out of control - if true, the former represents a worsening situation and the latter an improving situation regarding %MRSA U-chart The rate of MRSA bacteraemia was above its upper control limit in Q and below its lower control limit for Q2 2008–Q4 2009, (except for Q1 2008) indicating that out of control - if true, the former represents a worsening situation and the latter an improving situation regarding %MRSA Worsening/improving situations warrant further investigation to determine reasons why Statistical Process Charts

Rates of S. aureus and MRSA bacteraemia, Acute hospitals only (Total hospitals = Total acute hospitals in Ireland) 2 Bed Days Used (BDU) provided by the Acute Services Team in the Business Intelligence Unit, Corporate Planning and Corporate Performance (CPCP) section of the Health Service Executive for acute public hospitals and directly from the infection control/finance departments from acute private hospitals 3 Per 1,000 BDU: for 2004 and 2005, rates calculated using data from acute public hospitals only; for the period , rates calculated using data from all public and private acute hospitals for which both numerator (MRSA isolates) and denominator ( BDU) data available 4 Data from acute public hospitals only

Vancomycin-Intermediate S. aureus (VISA) reports from EARSS in 2009* In 2009, no MRSA isolates with reduced susceptibility to vancomycin were detected by the Etest macromethod In 2006, two VISA isolates were detected, which were the first reports of VISA from EARSS in Ireland: both were confirmed as VISA by CDC one was shown to be VISA and the other to be h-VISA by population analysis profiling (PAP) studies *Data from the National MRSA Reference Laboratory, where all EARSS MRSA isolates submitted by participating laboratories are tested for reduced susceptibility to vancomycin

Age distribution of patients with MRSA and MSSA bacteraemia in 2009

Age-specific incidence rates of MRSA and MSSA bacteraemia in 2009 ASIR, Age-Specific Incidence Rate (per 100,000 population)

Age and sex distribution of patients with MRSA bacteraemia in 2009

Age and sex-specific incidence rates of MRSA bacteraemia in 2009 ASIR, Age-Specific Incidence Rate (per 100,000 population)

Age and sex distribution of patients with MSSA bacteraemia in 2009

Age and sex-specific incidence rates of MSSA bacteraemia in 2009 ASIR, Age-Specific Incidence Rate (per 100,000 population)

Mean, median, mode and range of ages of patients with S. aureus (MRSA and MSSA) bacteraemia in 2009 The difference in median ages for patients with MRSA and MSSA bacteraemia is significant as the confidence intervals do not overlap

Relative risk of developing MRSA bacteraemia associated with age in 2009 In patients with laboratory-confirmed S. aureus bacteraemia in 2009, the probability that the infecting organism was MRSA as compared to MSSA was approximately1.7-times greater in patients aged ≥65years than in those aged <65 years

Sex distribution of patients with S. aureus (MRSA and MSSA) bacteraemia in 2009 In patients with laboratory-confirmed S. aureus bacteraemia in 2009, males were approximately 1.8-times more likely to get an infection (2.1-times for MRSA and 1.8-times for MSSA) than females. These findings were significant (P<0.0001)

Distribution of MRSA in EARSS/EARS-Net countries in 2009 Map downloaded from: on 20/12/2010

Distribution of MRSA in EARSS countries in 2008 Map downloaded from on 24/08/2009