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RESULTS of the SURVEILLANCE of METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS, from 1995 to 2009

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RESULTS of the SURVEILLANCE of METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS, from 1995 to 2009 (PDF Document - 677 KB - 14 pages)

There has been a gradual but continued increase in overall MRSA rates across the country. However, most of the increase is accounted for by greater numbers of colonized patients (reflecting perhaps widespread MRSA screening practices), with little or no increase in MRSA infection rates.  This could be viewed as a small measure of success of MRSA infection control in many institutions. However, nosocomial (i.e. originating from reporting acute care facility) infection rates remain significant, and account for nearly two-thirds of all cases.  It is also important to note the dramatic increase in community-associated cases (with no traditional risk factors associated with healthcare exposure) in the past 5 years; currently, almost a third of all new MRSA cases appear to be community-associated.

Nosocomial infections = Infections associated with the reporting acute care facility;

Healthcare-associated = Cases of infections or colonizations originating from exposure to any health procedure carried out in a healthcare facility including long term care facilities or clinics.

Table 1. Frequency of detection of MRSA in the CNISP network from 1995 to 2009
Surveillance year MRSAFootnote 1.1 Infections MRSA Colonizations Numerator Denominator
(patient-admissionsFootnote 1.2) (patient-daysFootnote 1.3
1995 106 83 189 374,027 2,907,905
1996 192 247 440 405,791 3,801,608
1997 293 358 653 418,465 3,625,997
1998 418 616 1,050 407,297 2,990,598
1999 513 1,381 1,953 510,095 4,078,163
2000 736 1,781 2,553 507,910 3,862,873
2001 696 1,602 2,328 614,421 4,967,214
2002 845 1,849 2,729 583,658 4,732,172
2003 1,064 2,390 3,465 671,240 5,611,833
2004 1,369 2,642 4,019 677,829 5,227,447
2005 2,067 3,427 5,636 764,341 6,493,286
2006 2,011 3,850 5,867 770,118 5,963,506
2007 1,952 4,335 6,287 768,294 5,695,520
2008 2,001 4,364 6,273 678,610 5,441,458
2009 2,036 4,610 6,646 701,477 5,374,036
Table 2. Regional distribution of MRSA infections & colonizations in the CNISP network from 1995 to 2009
Surveillance year MRSA INFECTIONS MRSA COLONIZATIONS
EastFootnote 2.2 CentreFootnote 2.1 WestFootnote 2.3 East Centre West
1995 5 56 45 4 55 24
1996 4 137 51 23 191 33
1997 16 171 106 16 293 49
1998 12 226 180 20 437 159
1999 11 371 131 29 998 354
2000 21 410 305 51 1,336 394
2001 28 416 252 50 1,243 309
2002 53 514 278 109 1,408 332
2003 99 592 373 251 1,818 321
2004 106 594 669 249 1,970 423
2005 193 687 1,187 308 2,364 755
2006 189 751 1,071 303 2,662 885
2007 207 618 1,127 312 2,816 1,207
2008 261 659 1,081 452 2,933 979
2009 217 858 961 312 3,176 1,122

Figure 1A: Overall MRSA rates, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 1A: Overall MRSA rates, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 1A
Figure 1A: Overall MRSA rates, CNISP 1995-2009 (per 1,000 patient-admissions)
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Overall MRSA rate 0.51 1.08 1.56 2.58 3.83 5.03 3.79 4.68 5.16 5.93 7.37 7.62 8.18 9.24 9.47
MRSA infection rate 0.28 0.47 0.70 1.03 1.01 1.45 1.13 1.45 1.59 2.02 2.70 2.61 2.54 2.95 2.90
MRSA colonization rate 0.22 0.61 0.86 1.51 2.71 3.51 2.61 3.17 3.56 3.90 4.48 5.00 5.64 6.43 6.57

Figure 2A: Healthcare-associated MRSA rates, CNISP 1995 - 2009 (per 1,000 patient-admissions)

Figure 2A: Healthcare-associated MRSA rates, CNISP 1995 - 2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 2A
Figure 2A: Healthcare-associated MRSA rates, CNISP 1995 - 2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Overall healthcare-associated MRSA rate 0.32 0.75 1.05 1.84 2.88 3.51 2.66 3.12 3.58 4.16 5.09 5.87 5.76 6.21 6.17
Healthcare-associated MRSA infection rate 0.17 0.27 0.42 0.65 0.71 0.98 0.71 0.85 1.02 1.19 1.64 1.81 1.67 1.93 1.96
Healthcare-associated MRSA colonization rate 0.15 0.48 0.62 1.18 2.13 2.49 1.93 2.25 2.56 2.96 3.33 4.06 4.09 4.27 4.21

Within healthcare settings, the occurrence of MRSA colonization dominates that of the infection. Over the years, the difference between rates of colonization and infection has steadily been getting wider. 

Figure 3A: Regional MRSA rates, CNISP 1995 to 2009 (per 1,000 patient-admissions)

Figure 3A: Regional MRSA rates, CNISP 1995 to 2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 3A
Figure 3A: Regional MRSA rates, CNISP 1995 to 2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
WEST 0.50 0.48 0.83 1.96 2.39 3.20 2.62 2.92 2.75 3.95 6.51 6.31 7.44 7.40 7.34
CENTRE 0.68 2.06 2.95 4.32 6.56 8.74 5.37 6.75 7.21 8.06 8.42 8.89 9.10 10.74 12.05
EAST 0.13 0.38 0.44 0.45 0.50 0.89 0.94 1.99 4.25 4.32 6.08 6.52 6.70 9.10 6.38

In the early years of surveillance, the East which was the region with the lowest MRSA (colonizations & infections combined) rates, has in the last six years produced rates as high as those reported in the West: an increase mainly driven by colonization. Central Canada on the other hand continues to post the highest rate in the country.

Figure 4A: Regional MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 4A: Regional MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 4A
Figure 4A: Regional MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
WEST 0.32 0.29 0.56 1.00 0.61 1.37 1.16 1.30 1.47 2.42 3.75 3.45 3.59 4.07 3.39
CENTRE 0.34 0.86 1.09 1.47 1.74 2.03 1.33 1.79 1.76 1.86 1.88 1.95 1.64 1.97 2.56
EAST 0.07 0.06 0.22 0.16 0.13 0.25 0.33 0.64 1.20 1.29 2.32 2.50 2.67 3.33 2.62

From 2002 to 2007, Central Canada recorded little or no increase in its MRSA infection rate, which by the way became the lowest in the country since 2005. However since 2007, it has been considerably increasing; a tendency opposite to the one seen in Eastern and Western Canada which in 2009 posted significantly lower rates than the year before.

The situation is somewhat reverse with regard to colonization since Central Canada is continuously recording the highest incidence rates in the country, and the West the lowest since 2002. The East is the only region where both colonization and infection patterns are similar.

Figure 5A: Regional MRSA COLONIZATION rates, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 5A: Regional MRSA COLONIZATION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 5A
Figure 5A: Regional MRSA COLONIZATION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
WEST 0.17 0.19 0.26 0.88 1.65 1.77 1.42 1.56 1.27 1.53 2.39 2.85 3.85 3.68 3.95
CENTRE 0.34 1.20 1.86 2.84 4.68 6.60 3.97 4.89 5.42 6.18 6.47 6.92 7.46 8.77 9.49
EAST 0.06 0.32 0.22 0.27 0.35 0.61 0.59 1.32 3.05 3.03 3.71 4.01 4.03 5.77 3.76

Figure 6A: Regional healthcare-associated MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 6A: Regional healthcare-associated MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
Figure 6A: Regional healthcare-associated MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions) - Text Equivalent
Figure 6A: Regional healthcare-associated MRSA INFECTION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
WEST 0.20 0.17 0.35 0.61 0.44 0.98 0.71 0.60 0.72 1.13 1.89 2.23 2.16 2.34 2.14
CENTRE 0.21 0.49 0.62 0.95 1.23 1.34 0.86 1.19 1.28 1.33 1.45 1.44 1.12 1.37 1.71
EAST 0.03 0.04 0.15 0.14 0.07 0.10 0.17 0.30 0.84 0.88 1.51 1.97 2.36 2.96 2.33

Since 2005, central Canada has been posting the lowest MRSA infection rates in the country, although from 1995 to 2004, it was the region with the highest infection rates.

Figure 7A: Regional healthcare-associated MRSA COLONIZATION rates, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 7A: Regional healthcare-associated MRSA COLONIZATION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 7A
Figure 7A: Regional healthcare-associated MRSA COLONIZATION rates, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
WEST 0.11 0.13 0.17 0.64 1.37 1.39 1.14 0.90 0.81 1.09 1.61 2.01 2.69 2.08 2.26
CENTRE 0.23 0.96 1.36 2.26 3.56 4.55 2.86 3.60 3.85 4.64 4.90 5.87 5.36 8.77 6.09
EAST 0.04 0.28 0.19 0.23 0.35 0.44 0.47 1.01 2.64 2.74 2.99 3.30 3.54 4.57 3.29

The slowdown in healthcare-associated MRSA infections rates noted in Central Canada was not seen with their MRSA colonization rates (per patient-admissions) which remained the highest in the country. In contrast, the West with the highest infection rates has been posting the lowest colonization rates in the country since 2002.

Figure 8A: Overall & healthcare-associted rates MRSA INFECTION, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 8A: Overall & healthcare-associted rates MRSA INFECTION, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 8A
Figure 8A: Overall & healthcare-associted rates MRSA INFECTION, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Overall 0.51 1.08 1.56 2.58 3.83 5.03 3.79 4.68 5.16 5.93 7.37 7.62 8.18 9.24 9.47
Healthcare-associated 0.32 0.75 1.05 1.84 2.88 3.51 2.66 3.12 3.58 4.16 5.09 5.87 5.76 6.21 6.17

The widening of the margin between the overall MRSA rates and the rates of healthcare-associated MRSA illustrates the growing importance of community-associated MRSA cases being detected in healthcare settings.

MRSA bacteraemia was on the rise from 2008 to 2009, recording an overall 8% increase in its rate. A much higher increase (over 27%) was recorded in reporting CNISP acute care facilities (nosocomial).

Figure 9A: Bacteraemic MRSA, CNISP 2008 - 2009 (per 1,000 patient-admissions)

Figure 9A: Bacteraemic MRSA, CNISP 2008 - 2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 9A
Figure 9A: Bacteraemic MRSA, CNISP 2008 - 2009 (per 1,000 patient-admissions)
  2008 2009
All bacteraemia 0.50 0.54
Healthcare-associated bacteraemia 0.32 0.37
Nosocomial bacteraemia 0.22 0.28
Surveillance year All bacteraemia Healthcare-associated bacteraemia Nosocomial bacteraemia Denominator (patient-admissions) Denominator (patient-days)
2008 338 219 150 678,610 5,441,458
2009 380 258 195 701,477 5,374,036

Healthcare-associated MRSA infections predominate in adult hospitals compared to paediatric hospitals where community-associated infections account for the majority of cases. From 2008 to 2009, healthcare-associated MRSA infection rates (per patient-admissions) were significantly lower in paediatric hospitals, whereas in adult and mixed hospitals, the changes were insignificant (Figure 10A).

Figure 10A: Healthcare-associated MRSA infections by hospital type, CNISP 2008-2009 (per 1,000 patient-admissions)

Figure 10A: Healthcare-associated MRSA infections by hospital type, CNISP 2008-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 10A
Figure 10A: Healthcare-associated MRSA infections by hospital type, CNISP 2008-2009 (per 1,000 patient-admissions)
  2008 2009
Adult hospitals 2.63 2.56
Paediatric hospitals 0.49 0.23
Mixed hospitals 1.16 1.20
National - CNISP 1.93 1.96

While a decrease of about 7% was registered in the community-associated MRSA infection rate (per patient-admissions) in paediatric hospitals from 2008 to 2009, adult hospitals were experiencing an increase of similar magnitude (Figure 10B).

Figure 10B: Community-associated MRSA infections by hospital type, CNISP 2008-2009 (per 1,000 patient-admissions)

Figure 10B: Community-associated MRSA infections by hospital type, CNISP 2008-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 10B
Figure 10B: Community-associated MRSA infections by hospital type, CNISP 2008-2009 (per 1,000 patient-admissions)
  2008 2009
Adult hospitals 0.58 0.62
Paediatric hospitals 1.57 1.46
Mixed hospitals 0.52 0.53
National - CNISP 0.64 0.66
Table 3. Healthcare & community-associated MRSA in paediatric patients
Surveillance year Healthcare-associated MRSAFootnote 3.1 Community-associated MRSA Denominator
Infection Colonization Infection Colonization (patient-admissions) (patient-days)
1995 0 1 0 0 25,468 131,629
1996 0 1 0 0 24,089 130,348
1997 0 1 0 0 29,952 142,543
1998 1 2 0 1 29,516 144,828
1999 2 3 1 2 31,804 195,434
2000 1 0 2 0 28,443 168,690
2001 2 1 0 2 35,695 199,428
2002 2 3 1 1 37,024 203,770
2003 3 6 1 3 38,170 216,225
2004 6 7 2 2 43,549 193,596
2005 9 16 8 2 44,376 228,621
2006 18 10 16 8 52,661 327,861
2007 12 14 61 22 50,518 327,704
2008 26 23 83 14 52,833 338,950
2009 12 84 76 35 52,204 339,526

Nosocomial infections = Infections associated with healthcare facilities in the CNISP network.

Healthcare-associated infections = Infections originating from hospitalization for 48 hours or more, or form an exposure to any medical procedure carried out in a hospital, clinic or a long-term care facility.

From 1995 to 2005, MRSA infection and colonization in paediatric patients occurred at comparable rates. However in 2006, the rate of infections became significantly higher than that of colonization and remained so until 2008, it’s only in 2009 that the patterns reversed considerably (Figures 11).

Figure 11A: MRSA incidence rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 11A: MRSA incidence rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 11A
Figure 11A: MRSA incidence rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Overall MRSA 0.04 0.12 0.10 0.17 0.31 0.28 0.45 0.51 0.55 0.71 1.19 1.25 2.51 3.22 4.83
Overall Infection Rate 0.00 0.00 0.03 0.07 0.13 0.14 0.17 0.16 0.24 0.37 0.65 0.84 1.74 2.31 1.90
Overall Colonization Rate 0.04 0.12 0.07 0.10 0.19 0.11 0.28 0.35 0.31 0.34 0.54 0.42 0.77 0.91 2.93

Figure 11B: MRSA incidence rates for paediatric patients, CNISP 1995 - 2009 (per 10,000 patient-days)

Figure 11B: MRSA incidence rates for paediatric patients, CNISP 1995 - 2009 (per 10,000 patient-days)
Text Equivalent - Figure 11B
Figure 11B: MRSA incidence rates for paediatric patients, CNISP 1995 - 2009 (per 10,000 patient-days)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Overall MRSA 0.08 0.23 0.21 0.35 0.51 0.47 0.80 0.93 0.97 1.60 2.32 2.01 3.88 5.02 7.42
Overall Infection Rate 0.00 0.00 0.07 0.14 0.20 0.24 0.30 0.29 0.42 0.83 1.27 1.34 2.69 3.60 2.92
Overall Colonization Rate 0.08 0.23 0.14 0.21 0.31 0.18 0.50 0.64 0.55 0.77 1.05 0.67 1.19 1.42 4.51

From 1995 to 2006, paediatric healthcare-associated MRSA (both infection & colonization) occurred at a rate slightly lower than community-associated only once (in the year 2000). However in 2007, community-associated rate jumped to a level three times that of healthcare-associated which remained almost unchanged. This difference margin subsequently decreased in the following years (Figure 12A).

Figure 12A: Healthcare- & community-associated MRSA rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 12A: Healthcare- & community-associated MRSA rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 12A
Figure 12A: Healthcare- & community-associated MRSA rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Healthcare-associated Rate 0.04 0.04 0.03 0.10 0.16 0.04 0.08 0.14 0.24 0.30 0.56 0.53 0.51 0.93 1.84
Community-associated  Rate 0.00 0.00 0.00 0.03 0.09 0.07 0.06 0.05 0.10 0.09 0.23 0.46 1.64 1.84 2.13

Changes in the overall paediatric MRSA rates observed from 2007 onward have largely been driven by community-associated infection rates (Figure 12B) and those of healthcare-associated colonization (Figure 12C).

Figure 12B: Healthcare- & community-associated MRSA INFECTION rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 12B: Healthcare- & community-associated MRSA INFECTION rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 12B
Figure 12B: Healthcare- & community-associated MRSA INFECTION rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Healthcare-associated Rate 0.00 0.00 0.00 0.03 0.06 0.04 0.06 0.05 0.08 0.14 0.20 0.34 0.24 0.49 0.23
Community-associated Rate 0.00 0.00 0.00 0.00 0.03 0.07 0.00 0.03 0.03 0.05 0.18 0.30 1.21 1.57 1.46

Figure 12C: Healthcare- & community-associated MRSA COLONIZATION rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)

Figure 12C: Healthcare- & community-associated MRSA COLONIZATION rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
Text Equivalent - Figure 12C
Figure 12C: Healthcare- & community-associated MRSA COLONIZATION rates for paediatric patients, CNISP 1995-2009 (per 1,000 patient-admissions)
  1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Healthcare-associated Rate 0.04 0.04 0.03 0.07 0.09 0.00 0.03 0.08 0.16 0.16 0.36 0.19 0.28 0.44 1.61
Community-associated Rate 0.00 0.00 0.00 0.03 0.06 0.00 0.06 0.03 0.08 0.05 0.05 0.15 0.44 0.26 0.67

CMRSA2 emerged gradually from the early days of the current surveillance to establish itself as the most widely distributed strain in Canada among adult patients, followed by CMRSA10, which has emerged as an important epidemiological strain only since 2004 (Figures 13A & 13B). CMRSA1 & CMRSA3/6 hit their peak in 2000 and have rapidly declined to insignificant levels although from 2006, infections due to CMRSA3/6 and CMRSA7 significantly increased. 

Figure 13A: Distribution of MRSA strains from infected cases, CNISP 1995-2007

Figure 13A: Distribution of MRSA strains from infected cases, CNISP 1995-2007
Text Equivalent - Figure 13A
Figure 13A: Distribution of MRSA strains from infected cases, CNISP 1995-2007
  CMRSA1 CMRSA2 CMRSA3/6 CMRSA4 CMRSA5 CMRSA7 CMRSA8 CMRSA9 CMRSA10 Others (non-CMRSAs)
1995  (n=98) 23 16 34 10 4 2 0 0 0 9
1996 (n=102) 25 25 14 25 9 1 0 0 0 3
1997 (n=232) 109 39 29 7 40 0 1 1 0 6
1998 (n=328) 124 30 84 9 65 7 0 0 0 9
1999 (n=311) 161 52 61 8 16 2 1 1 1 8
2000 (n=552) 173 151 164 17 12 6 16 2 2 9
2001 (n=326) 114 129 26 6 7 12 4 15 0 13
2002 (n=355) 67 180 50 6 3 15 12 8 2 12
2003 (n=478) 58 277 46 30 4 15 8 12 14 14
2004 (n=596) 44 348 53 30 5 21 10 7 61 17
2005 (n=748) 39 432 50 25 2 26 17 5 131 21
2006 (n=1364) 23 702 93 45 7 69 16 1 369 39
2007 (n=1315) 10 678 97 35 7 87 13 2 364 22

Figure 13B: Distribution of MRSA strains from infected cases, CNISP 2008-2009*

Figure 13B: Distribution of MRSA strains from infected cases, CNISP 2008-2009*

* Only three-month data for each surveillance year were considered.

Text Equivalent - Figure 13B
Figure 13B: Distribution of MRSA strains from infected cases, CNISP 2008-2009
  CMRSA1 CMRSA2 CMRSA3/6 CMRSA4 CMRSA5 CMRSA7 CMRSA8 CMRSA9 CMRSA10 Others (non-CMRSAs)
2008 (n=711) 9 384 40 10 2 46 9 0 187 24
2009 (n=620) 4 356 26 4 1 21 19 1 170 18

N.B. Cautious interpretations of regional differences in the overall MRSA rates and colonization rates are recommended, because screening policies may differ from one province to another.

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