The latest report from the Canadian Antimicrobial Resistance Surveillance System (CARSS) shows rates of antimicrobial resistance remaining stable in the country, with some declines in select drug-resistant pathogens but some worrisome findings.
The CARRS Report 2016 is the second published by the Public Health Agency of Canada (PHAC) and includes surveillance data on antimicrobial resistance and use, both in humans and animals, through 2014. The report is based on available surveillance data from the PHAC's nine surveillance systems and laboratory reference services.
Declines in MRSA, VRE, and C diff infections
Among the positive trends documented in the CARSS report is a 25% decrease in methicillin-resistant Staphylococcus aureus (MRSA) infections since 2008, driven mainly by a reduction in healthcare-associated MRSA infections. This trend, the report notes, mirrors a decline in MRSA infections seen in the United States.
The report also shows a second year of decline in vancomycin-resistant Enterococcus infections, with the rate of VRE infections dropping to 0.45 cases per 10,000 patient days from a peak of 0.61 cases per 10,000 patient days in 2012. This comes at a time when VRE infections are increasing in prevalence worldwide. And, following a decade of increases, rates of Clostridium difficile infections in hospitalized patients declined in 2014, from 5.2 cases per 1,000 patient admissions to 3.4 cases.
But the report warns that those positive trends come amid a steady rise in drug resistance since 2007. "That said, incidence rates of MRSA and VRE have not decreased to levels seen before 2007 when increases in resistance began, indicating that more work needs to be done to reverse the problem," the authors write.
In addition, the report highlights another trend that's also been seen in the United States: an increase in gonorrhea infections accompanied by rising resistance in Neisseria gonorrhea to the last available treatment options. Surveillance data indicate that N gonorrhea isolates in Canada are showing a significant increase in resistance to azithromycin and a smaller drop in susceptibility to cefixime and ceftriaxone.
"Despite the small numbers, this is of concern as it represents a threat to the success of currently recommended dual therapy treatment options," the report states. Between 2003 and 2014, reported case of gonorrhea rose by 43.1% in Canada.
The report also provides data on drug resistance in three bacteria found in food sources across Canada: Escherichia coli, Salmonella, and Campylobacter. Isolates were collected from healthy animals (chickens, pigs, and cattle) on the farm, healthy animals at slaughter, and from meat at retail food stores. The surveillance data suggest that levels of resistance in these bacteria remained steady in 2014.
Antimicrobial use in humans, animals
The CARSS data on antimicrobial use in humans also show some encouraging trends in stewardship. Overall, 23 million antibiotic prescriptions were dispensed in Canada in 2014, and 17.8 defined daily doses (DDDs) were dispensed per 1,000 inhabitants per day through community pharmacies. These numbers have remained relatively stable since 2007. When compared with the 30 countries of the European Union, Canada has the 12th lowest level of outpatient antimicrobial use.
Most significantly, the report shows that antibiotic prescribing rates in children under 14 have dropped by 8% since 2010, and by 3% in adults under 60 over the same period. The report also shows, however, that antibiotics were commonly prescribed for two viral infections, with 82% of acute sinusitis infections and 77% of acute bronchitis infections resulting in a recommendation for an antimicrobial.
In addition, the report found that antibiotic use in animals in Canada, a country with 19 times more animals than humans, remains problematic. Overall, 1.5 million kilograms (kg) of antimicrobial active ingredients were distributed to animals in 2014—a 5% increase over 2013. And of the 1.4 million kg of medically important antimicrobials sold in the country, 82% were intended for production animals.
While antimicrobials are used in Canadian food-producing animals for disease treatment and prevention, they also are used for growth promotion—a practice that is no longer permitted in the European Union.
Surveillance gaps
The CARSS report also identified several gaps in surveillance that need addressing for a more complete picture of antimicrobial resistance and use. Among those are lack of data on resistant E coli, N gonorrhea, and Shigella; limited drug resistance data in the community, outpatient clinics, doctor's offices, and long-term care facilities; and limited data on antibiotic use in animals.
"Expanding surveillance activities to collect quality data regarding health professional prescribing practices, infection rates, and resistance patterns for priority organisms, particularly in the community setting, will be the priority of PHAC's work over the coming year," the authors write.
See also:
Sep 12 Canadian Antimicrobial Surveillance System Report 2016
