Antimicrobial resistance surveillance in Ireland Results of invasive Staphylococcus aureus infection (blood) surveillance (2009Q1-4) **** Data as of 14/04/2010

Antimicrobial resistance Antimicrobial resistance surveillance in Irelandsurveillance in Ireland

Results of invasive Staphylococcus aureus infection

(blood) surveillance (2009Q1-4)**** Data as of 14/04/2010 ******** Data as of 14/04/2010 ****

Ireland is a member of the European Antimicrobial Resistance Surveillance System (EARSS)

EARSS EARSS S. aureusS. aureus::Objective and case definitionObjective and case definition

Objective:

To determine the proportions of S. aureus isolates from blood that are resistant to meticillin

Case definition:

EARSS collects data on the first invasive isolate (from blood only) of S. aureus per patient per quarter

Caveats in interpreting EARSS dataCaveats in interpreting EARSS data

Care must be exercised when interpreting the raw figures, i.e. increases in numbers of isolates, as the numbers of laboratories reporting to EARSS has increased over the years

EARSS 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 EARSS in Ireland, including quarterly and annual reports, plus reference/ resource material on the individual pathogens under surveillance, see:

http://www.ndsc.ie/hpsc/A-Z/MicrobiologyAntimicrobialResistance/

EuropeanAntimicrobialResistanceSurveillanceSystemEARSS/

Antibiotic codes and abbreviations:Antibiotic codes and abbreviations:

CIP, Ciprofloxacin ERY, ErythromycinFUS, Fusidic Acid GEN, GentamicinLIN, Lincomycin LNZ, LinezolidMET, Meticillin MUP, MupirocinOXA, Oxacillin PEN, PenicillinRIF, Rifampicin TCY,

TetracyclineTEI, Teicoplanin VAN, Vancomycin

SAU, Staphylococcus aureusMRSA, Meticillin-Resistant S. aureusMSSA, Meticillin-Susceptible S. aureusVISA, Vancomycin-Intermediate S. aureus

Numbers and proportions of Numbers and proportions of S. aureusS. aureus/MRSA /MRSA from bacteraemia with 95% confidence from bacteraemia with 95% confidence Intervals (CI), 1999-2009Q1-4* Intervals (CI), 1999-2009Q1-4*

* Data for 2009 provisional up to the end of Q4

Time period

Number of labs

Number of S. aureus

Number of MRSA

%MRSA (95%CI)

1999 11 510 198 38.8 (34.6-43.1)2000 18 639 249 39.0 (35.2-42.7)2001 20 816 337 41.3 (37.9-44.7)2002 23 1042 445 42.7 (39.7-45.7)2003 28 1140 480 42.1 (39.2-45.0)2004 41 1323 553 41.8 (39.1-44.5)2005 42 1424 592 41.6 (39.0-44.1)2006 42 1412 592 41.9 (39.4-44.5)2007 44 1393 536 38.5 (35.9-41.0)2008 43 1303 439 33.7 (31.1-36.3)2009* 44 1309 355 27.1 (24.7-29.5)

2009Q1 44 343 103 30.0 (25.2-34.9)2009Q2 44 328 92 28.0 (23.2-32.9)2009Q3 44 336 87 25.9 (21.2-30.6)2009Q4 44 302 73 24.2 (19.3-29.0)

S. aureusS. aureus/MRSA bacteraemia trends, /MRSA bacteraemia trends, 1999-2009Q1-4*1999-2009Q1-4*

* Data for 2009 provisional up to the end of Q4Number of laboratories participating by year-end and quarter are indicated above the bars

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18 282320 424241 4411 43 4444 4444 44

S. aureusS. aureus/MRSA bacteraemia trends by quarter, /MRSA bacteraemia trends by quarter, 2002-2009Q1-4*2002-2009Q1-4*

* Data for 2009 provisional up to the end of Q4;Number of laboratories participating by year-end indicated above the Q4 bars

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23 28 41 42 42 44 43 44

S. aureusS. aureus/MRSA bacteraemia trends, /MRSA bacteraemia trends, 2002-2009Q1-4*: 4-quarterly moving average2002-2009Q1-4*: 4-quarterly moving average

* Data for 2009 provisional up to the end of Q4;Number of laboratories participating by year-end indicated above the Q4 bars

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4-Quarter period ending…..Total S.aureus MRSA %MRSA

23 28 41 42 42 44 43 44

Numbers of Numbers of S. aureus S. aureus bacteraemia isolates bacteraemia isolates and %MRSA by Hospital Network, 2009Q1-4and %MRSA by Hospital Network, 2009Q1-4

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

NHO Hospital Network

Total S.aureus MRSA MSSA %MRSA

Dub/M 186 42 144 22.6%

Dub-N 228 48 180 21.1%

Dub-S 219 60 159 27.4%

MW 71 27 44 38.0%

NE 65 18 47 27.7%

S 177 49 128 27.7%

SE 120 30 90 25.0%

W/NW 187 76 111 40.6%Other 8 2 6 25.0%Private 48 3 45 6.3%ROI TOTAL 1309 355 954 27.1%

Proportion of Proportion of S. aureus S. aureus bacteraemia isolates bacteraemia isolates by Hospital Network, 2009Q1-4 (n=1309)by Hospital Network, 2009Q1-4 (n=1309)

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Hospital NetworkTotal S.aureus %MRSA

Numbers of Numbers of S. aureus S. aureus bacteraemia isolates, bacteraemia isolates, %MRSA and rates by Hospital Network, %MRSA and rates by Hospital Network, 2009Q1-42009Q1-4

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

NHO Hospital Network BDU 2009

No. Hospitals

Total S.aureus MRSA MSSA %MRSA

S. aureus rate

MRSA rate

MSSA rate

Dub/M 543,541 7 186 42 144 22.6% 0.34 0.08 0.26

Dub-N 607,701 6 228 48 180 21.1% 0.38 0.08 0.30

Dub-S 633,185 7 219 60 159 27.4% 0.35 0.09 0.25

MW 245,202 6 71 27 44 38.0% 0.29 0.11 0.18

NE 239,488 4 65 18 47 27.7% 0.27 0.08 0.20

S 472,762 7 177 49 128 27.7% 0.37 0.10 0.27

SE 371,601 5 120 30 90 25.0% 0.32 0.08 0.24

W/NW 572,167 6 187 76 111 40.6% 0.33 0.13 0.19ROI TOTAL 3,685,647 48 1253 350 903 27.9% 0.34 0.09 0.25

Numbers, proportions and rates of MRSA Numbers, proportions and rates of MRSA bacteraemia by hospital type, 2009Q1-4bacteraemia by hospital type, 2009Q1-4

*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

Hospital TypeNumber of hospitals

Bed days used (BDU)

Total S. aureus

Total MRSA %MRSA

MRSA rate/ 1000 BDU

Acute Public HospitalsTertiary/Specialist 9 1,796,139 698 201 28.8% 0.11Secondary 20 1,291,156 401 129 32.2% 0.10Primary 8 219,042 57 14 24.6% 0.06Obs/Gynae* 4 190,504 41 1 2.4% 0.01Paediatric* 2 91,372 43 2 4.7% 0.02Orthopaedic* 4 49,858 1 0 0.0% 0.00Other* 2 47,576 12 3 25.0% 0.06Total Acute 49 3,685,647 1253 350 27.9% 0.09

Private/Non-Acute Public HospitalsPrivate (General/Specialist) 3 120,315 17 2 11.8% 0.02Private (General/Specialist)^ 9 ** 31 1 3.2% **Non-Acute/Community *** ** 8 2 0.0% **

TOTAL 61 *** 1309 355 27.1% ***

Note: BDU provided by the

Rates of Rates of S. aureus S. aureus bacteraemia isolates by bacteraemia isolates by Hospital Network*, 2009Q1-4 (n=1253)Hospital Network*, 2009Q1-4 (n=1253)

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* excludes private hospitals and other non-acute facilities

Rates of MRSARates of MRSA bacteraemia isolates by bacteraemia isolates by Hospital Network, 2009Q1-4 (n=350)Hospital Network, 2009Q1-4 (n=350)


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Rates of MSSARates of MSSA bacteraemia isolates by bacteraemia isolates by Hospital Network, 2009Q1-4 (n=903)Hospital Network, 2009Q1-4 (n=903)


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Susceptibility data for Susceptibility data for S. aureus S. aureus bacteraemia bacteraemia isolates, 2009Q1-4 (n=1309)isolates, 2009Q1-4 (n=1309)

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AntibioticResistant Susceptible

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27.1%

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30.1% 2.3%

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Susceptibility data for MRSASusceptibility data for MRSA bacteraemia bacteraemia isolates, 2009Q1-4 (n=355)isolates, 2009Q1-4 (n=355)

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Susceptibility data for MSSASusceptibility data for MSSA bacteraemia bacteraemia isolates, 2009Q1-4 (n=954)isolates, 2009Q1-4 (n=954)

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84.5%

Antibiogram results for MRSA isolates Antibiogram results for MRSA isolates referred to NMRSARL, 2009Q1-4 (n=321) referred to NMRSARL, 2009Q1-4 (n=321)

Data provided by National MRSA Reference Laboratory, St James’s Hospital

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CHL CIP ERY FUS GEN LIN LNZ MUP RIF TCY TMP VAN

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Resistant Intermediate Susceptible

Trends in proportion of gentamicin resistance Trends in proportion of gentamicin resistance among MRSA isolates^, 1999-2009Q1-4among MRSA isolates^, 1999-2009Q1-4

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YearTotal MRSA tested for GEN-R GEN-R MRSA %GEN-R MRSA

18 282320 424241 4411 43 44

^ Data from National MRSA Reference Laboratory; Changes in the numbers of participating laboratories are indicated above the bars; * 2009 data are provisional

Trends in proportion of fusidic acid resistance Trends in proportion of fusidic acid resistance among MRSA isolates^, 1999-2009Q1-4among MRSA isolates^, 1999-2009Q1-4

^ Data from National MRSA Reference Laboratory; Changes in the numbers of participating laboratories are indicated above the bars; * 2009 data are provisional

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18 282320 424241 4411 43 44

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 ChartsStatistical 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 mean12 of 14 consecutive values on same side of the mean8 consecutive values either increasing or decreasingCyclic or periodic behaviour


Statistical Process ChartStatistical Process ChartNational MRSA proportions: P-Chart National MRSA proportions: P-Chart

Mean proportion calculated from data for Q1 2002-Q3 2009;UWL and LWL, Upper and Lower Warning Limits; UAL and LAL (±2 Standard Deviations), Upper and Lower Action Limits (±3 Standard Deviations)

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Statistical Process Chart Statistical Process Chart National MRSA rates: U-Chart National MRSA rates: U-Chart

Mean rate calculated from data for Q1 2004-Q3 2009; UWL and LWL, Upper and Lower Warning Limits (±2 Standard Deviations); UAL and LAL, Upper and Lower Action Limits (±3 Standard Deviations)

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P-chart: The proportion of MRSA bacteraemia was above its

upper control limit in Q2 2002, Q2 2003 and Q3 2006 and below its lower control limit for Q4 2007 and Q2 2008–Q4 2009. 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 Q2 2005 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


Rates of Rates of S. aureusS. aureus and MRSA bacteraemia, and MRSA bacteraemia, 2004-2009Q1-42004-2009Q1-4

* Acute public hospitals only

** Bed days used (BDU) calculated from Acute Public Hospital Activity data for acute

public hospitals participating in EARSS

*** Per 1,000 bed days used

YearNo. hospitals*

(Total hospitals)Bed Days

Used**Total

S.aureus MRSA %MRSAMRSA rate***

2004 57 (58) 3,728,566 1282 545 42.5% 0.15

2005 57 (58) 3,792,972 1367 577 42.2% 0.15

2006 53 (53) 3,722,832 1353 572 42.3% 0.15

2007 52 (52) 3,747,184 1339 526 39.3% 0.14

2008 50 (51) 3,693,026 1259 425 33.8% 0.12

2009Q1-4 48 (48) 3,685,647 1253 350 27.9% 0.09

VVancomycin-ancomycin-IIntermediate ntermediate SS. . aaureusureus (VISA) (VISA) reports from EARSS in 2009*reports from EARSS in 2009*

In 2008, 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 Age distribution of patients with MRSA and MSSA bacteraemia in MSSA bacteraemia in 20082008

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Age-specific incidence rates of MRSA Age-specific incidence rates of MRSA and MSSA bacteraemia in and MSSA bacteraemia in 20082008

ASIR, Age-Specific Incidence Rate (per 100,000 population)

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Age GroupMRSA MSSA TOTAL

Age and sex distribution of patients with Age and sex distribution of patients with MRSA bacteraemia in MRSA bacteraemia in 20082008

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Age and sex-specific incidence rates of Age and sex-specific incidence rates of MRSA bacteraemia in MRSA bacteraemia in 20082008


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Age and sex distribution of patients with Age and sex distribution of patients with MSSA bacteraemia in MSSA bacteraemia in 20082008

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Age and sex-specific incidence rates of Age and sex-specific incidence rates of MSSA bacteraemia in MSSA bacteraemia in 20082008


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female male TOTAL

Mean, median, mode and range of ages of Mean, median, mode and range of ages of patients with patients with S. aureusS. aureus (MRSA and MSSA) (MRSA and MSSA) bacteraemia in bacteraemia in 20082008

The difference in median ages for patients with MRSA and MSSA bacteraemia is significant as the confidence intervals do not overlap

MRSA MSSA SAU

n 435 854 1289

n with age 434 852 1286

Mean 66.5y 52.7y 57.4y

Median 72y (70-74y) 59y (57-61y) 64y (62-66y)

Mode 78y 0y 0y

Range 0-96y 0-97y 0-97y

Relative risk of developing MRSA bacteraemia Relative risk of developing MRSA bacteraemia associated with age in associated with age in 20082008

In patients with laboratory-confirmed S. aureus bacteraemia in 2008, the probability that the infecting organism was MRSA as compared to MSSA was over 2-times greater in patients aged ≥65years than in those aged <65 years

MRSA MSSA Total

>=65y 290 337 627

<65y 144 515 659

Total 434 852 1286

Relative risk (RR) = (347/669)/(190/724)2.116671

= 2.12 (95% CI: 1.79-2.50)

Chi-squared 85.9

P-value <0.0001

Sex distribution of patients with Sex distribution of patients with S. aureusS. aureus (MRSA and MSSA) bacteraemia in (MRSA and MSSA) bacteraemia in 20082008

In patients with laboratory-confirmed S. aureus bacteraemia in 2008, males were approximately 1.6-times more likely to get an infection (1.5-times for MRSA and 1.7-times for MSSA) than females. These findings were significant (P<0.0001)

MRSA MSSA SAU

No. male 260 535 795

%male 40.1 62.7 61.8

No. female 174 318 492

%female 59.9 37.3 38.2

m/f ratio 1.49 1.68 1.62

z-test 4.21 7.68 8.69

P-value <0.0001 <0.0001 <0.0001

Distribution of MRSA in EARSS countries Distribution of MRSA in EARSS countries in 2008in 2008

Map downloaded from http://www.rivm.nl/earss/database/ on 24/08/2009





Documents

Antimicrobial resistance surveillance in Ireland Results of invasive Staphylococcus aureus infection (blood) surveillance (2009Q1-4) **** Data as of 14/04/2010