Robyn Mitchell

Molecular epidemiology of vancomycin-resistant enterococcal bacteraemia: results from the Canadian Nosocomial Infection Surveillance Program, 1999–2009

OBJECTIVES Vancomycin-resistant enterococci (VRE) can be associated with serious bacteraemia. The focus of this study was to characterize the molecular epidemiology of VRE from bacteraemia cases that were isolated from 1999 to 2009 as part of Canadian Nosocomial Infection Surveillance Program (CNISP) surveillance activities. METHODS From 1999 to 2009, enterococci were collected from across Canada in accordance with the CNISP VRE surveillance protocol. MICs were determined using broth microdilution. PCR was used to identify vanA, B, C, D, E, G and L genes. Genetic relatedness was examined using multilocus sequence typing (MLST). RESULTS A total of 128 cases of bacteraemia were reported to CNISP from 1999 to 2009. In 2007, a significant increase in bacteraemia rates was observed in western and central Canada. Eighty-one of the 128 bacteraemia isolates were received for further characterization and were identified as Enterococcus faecium. The majority of isolates were from western Canada (60.5%), followed by central (37.0%) and eastern (2.5%) Canada. Susceptibilities were as follows: daptomycin, linezolid, tigecycline and chloramphenicol, 100%; quinupristin/dalfopristin, 96.3%; high-level gentamicin, 71.6%; tetracycline, 50.6%; high-level streptomycin, 44.4%; rifampicin, 21.0%; nitrofurantoin, 11.1%; clindamycin, 8.6%; ciprofloxacin, levofloxacin and moxifloxacin, 1.2%; and ampicillin, 0.0%. vanA contributed to vancomycin resistance in 90.1% of isolates and vanB in 9.9%. A total of 17 sequence types (STs) were observed. Beginning in 2006 there was a shift in ST from ST16, ST17, ST154 and ST80 to ST18, ST412, ST203 and ST584. CONCLUSIONS The increase in bacteraemia observed since 2007 in western and central Canada appears to coincide with the shift of MLST STs. All VRE isolates remained susceptible to daptomycin, linezolid, chloramphenicol and tigecycline.

Impact of the 2009 influenza A (H1N1) pandemic on Canadian health care workers: A survey on vaccination, illness, absenteeism, and personal protective equipment

BACKGROUND Data are limited on the impact of the 2009 H1N1 influenza A pandemic on health care worker (HCW) vaccination, illness, absenteeism, and personal protective equipment (PPE) use. METHODS A survey was completed by HCWs from 14 hospitals participating in the Canadian Nosocomial Infection Surveillance Program who provided direct care to patients with pH1N1 influenza in high-risk units between September and December 2009. RESULTS Surveys were returned from 986 HCWs (80% nurses, 14% respiratory therapists, and 6% physicians). HCWs working in an intensive care unit (78%) or a designated influenza ward (67%) were more compliant with wearing an N95 respirator for aerosol-generating medical procedures than those working in an emergency department (47%; P < .001). HCWs who worked in health care for >11 years were more compliant with wearing protective eyewear than those who worked for ≤11 years (69% vs 54%; P < .001). A total of 815 HCWs (83%) reported having received the pH1N1 influenza vaccine, and 372 (38%) reported having received the 2009-2010 seasonal influenza vaccine. Influenza-like illness was reported by 236 (24%) HCWs, 170 of whom (72%) reported missing work. CONCLUSIONS Experience working in health care improves PPE use and HCWs in emergency departments should be targeted for interventions to improve PPE compliance. pH1N1 influenza vaccine coverage was high, but seasonal influenza vaccine coverage was low, and significant HCW illness and absenteeism were reported.

Healthcare-Associated Influenza in Canadian Hospitals from 2006 to 2012

OBJECTIVE To determine trends, patient characteristics, and outcome of patients with healthcare-associated influenza in Canadian hospitals. DESIGN Prospective surveillance of laboratory-confirmed influenza among hospitalized adults was conducted from 2006 to 2012. Adults with positive test results at or after admission to the hospital were assessed. Influenza was considered to be healthcare associated if symptom onset was equal to or more than 96 hours after admission to a facility or if a patient was readmitted less than 96 hours after discharge or admitted less than 96 hours after transfer from another facility. Baseline characteristics of influenza patients were collected. Patients were reassessed at 30 days to determine the outcome. SETTING Acute care hospitals participating in the Canadian Nosocomial Infection Surveillance Program. RESULTS A total of 570 (17.3%) of 3,299 influenza cases were healthcare associated; 345 (60.5%) were acquired in a long-term care facility (LTCF), and 225 (39.5%) were acquired in an acute care facility (ACF). There was year-to-year variability in the rate and proportion of cases that were healthcare associated and variability in the proportion that were acquired in a LTCF versus an ACF. Patients with LTCF-associated cases were older, had a higher proportion of chronic heart disease, and were less likely to be immunocompromised compared with patients with ACF-associated cases; there was no significant difference in 30-day all-cause and influenza-specific mortality. CONCLUSIONS Healthcare-associated influenza is a major component of the burden of disease from influenza in hospitals, but the proportion of cases that are healthcare associated varies markedly from year to year, as does the proportion of healthcare-associated infections that are acquired in an ACF versus an LTCF.

Understanding the burden of influenza infection among adults in Canadian hospitals: A comparison of the 2009-2010 pandemic season with the prepandemic and postpandemic seasons

BACKGROUND The degree to which the 2009-2010 influenza pandemic season differed from previous and subsequent influenza seasons in Canadian hospitals has not yet been assessed. METHODS Surveillance for laboratory-confirmed influenza among adults in 51 Canadian Nosocomial Infection Surveillance Program hospitals was conducted between November 1, 2006, and May 31, 2011. Inpatient characteristics, treatment, and outcomes of influenza cases in the pandemic season (2009-2010) were compared with those in the prepandemic (2006-2007 to 2008-2009) and postpandemic (2010-2011) seasons. RESULTS The incidence of influenza infection was lower in the postpandemic season (1.59/1,000 admissions) compared with the prepandemic seasons (2.00/1,000 admissions; P < .001) and the pandemic season (1.80/1,000 admissions; P < .001). The proportion of cases classified as health care-associated was much smaller during the pandemic season (6.6%) than in either the prepandemic season (23.2%; P < .001) or the postpandemic season (23.6%; P < .001). Inpatients in the pandemic season were significantly younger compared with those in the prepandemic and postpandemic seasons (P < .001). Inpatients in the pandemic season were less likely to have been vaccinated (P < .001), but more likely to be treated with antiviral agents (P < .001), than inpatients in both the prepandemic and postpandemic seasons. Intensive care unit admission was greater during the pandemic season, but there were no significant differences in 30-day mortality among the seasons. CONCLUSIONS Among adult inpatients, the pH1N1 pandemic season differed from seasonal influenza in terms of age, vaccination status, antiviral use, and intensive care unit admission, but not in terms of 30-day mortality.

Laboratory-Confirmed Pandemic H1N1 Influenza in Hospitalized Adults: Findings from the Canadian Nosocomial Infections Surveillance Program, 2009-2010

Surveillance for pandemic H1N1 influenza was conducted between June 1, 2009, and May 31, 2010, among adults at 40 participating hospitals in the Canadian Nosocomial Infection Surveillance Program. The first wave was characterized by a higher proportion of Aboriginals and pregnant women as well as severe outcomes, compared to the second wave.

How reliable are national surveillance data? Findings from an audit of Canadian methicillin-resistant Staphylococcus aureus surveillance data

BACKGROUND The Canadian Nosocomial Infection Surveillance Program (CNISP) has conducted surveillance for incident cases of methicillin-resistant Staphylococcus aureus (MRSA) in sentinel hospitals since 1995. In 2007, a reliability audit of the 2005 data was conducted. METHODS In 2005, 5,652 cases were submitted to the CNISP from 43 hospitals. A proportional sample of submitted forms (up to 25) from each site were randomly selected. Stratified random sampling was used to obtain the comparison data. The original data were compared with the reabstracted data for congruence on 7 preselected variables. RESULTS Reabstracted data were received from 30 out of 43 hospitals (70%), providing 443 of the 598 case forms requested (74%). Of these, 397 (90%) had matching case identification numbers. Overall, the percentage of discordant responses was 7.0%, ranging from 3.5% for sex and up to 23.7% for less well-defined variables (eg, where MRSA was acquired). CONCLUSION Our findings suggest that, in general, the 2005 MRSA data are reliable. However to improve reliability a data quality framework with quality assurance practices, including ongoing auditing should be integrated into the CNISPs surveillance programs. Providing training to data collectors and standard definitions with practical examples may help to improve data quality, especially for those variables that require clinical judgment.

Periprosthetic Infection following Primary Hip and Knee Arthroplasty: The Impact of Limiting the Postoperative Surveillance Period

BACKGROUND Hip and knee arthroplasty infections are associated with considerable healthcare costs. The merits of reducing the postoperative surveillance period from 1 year to 90 days have been debated. OBJECTIVES To report the first pan-Canadian hip and knee periprosthetic joint infection (PJI) rates and to describe the implications of a shorter (90-day) postoperative surveillance period. METHODS Prospective surveillance for infection following hip and knee arthroplasty was conducted by hospitals participating in the Canadian Nosocomial Infection Surveillance Program (CNISP) using standard surveillance definitions. RESULTS Overall hip and knee PJI rates were 1.64 and 1.52 per 100 procedures, respectively. Deep incisional and organ-space hip and knee PJI rates were 0.96 and 0.71, respectively. In total, 93% of hip PJIs and 92% of knee PJIs were identified within 90 days, with a median time to detection of 21 days. However, 11%-16% of deep incisional and organ-space infections were not detected within 90 days. This rate was reduced to 3%-4% at 180 days post procedure. Anaerobic and polymicrobial infections had the shortest median time from procedure to detection (17 and 18 days, respectively) compared with infections due to other microorganisms, including Staphylococcus aureus. CONCLUSIONS PJI rates were similar to those reported elsewhere, although differences in national surveillance systems limit direct comparisons. Our results suggest that a postoperative surveillance period of 90 days will detect the majority of PJIs; however, up to 16% of deep incisional and organ-space infections may be missed. Extending the surveillance period to 180 days could allow for a better estimate of disease burden. Infect Control Hosp Epidemiol 2017;38:147-153.

Laboratory-confirmed pandemic H1N1 influenca in hospitalized adults – findings from the Canadian Nosocomial Infection Surveillance Program (CNISP), 2009-10

In response to the spread of the pandemic H1N1 (pH1N1) influenza virus in 2009, the Canadian Nosocomial Infection Surveillance Program (CNISP) extended its seasonal influenza surveillance to year-round reporting in order to describe the epidemiology and outcomes of pH1N1 in hospitalized adults. This report describes the findings of the surveillance program during the first year of pH1N1 influenza.

Results from the Canadian Nosocomial Infection Surveillance Program for detection of carbapenemase-producing Acinetobacter spp. in Canadian hospitals, 2010–16

Objectives Globally there is an increased prevalence of carbapenem-resistant Acinetobacter spp. (CRAs) and carbapenemase-producing Acinetobacter spp. (CPAs) in the hospital setting. This increase prompted the Canadian Nosocomial Infection Surveillance Program (CNISP) to conduct surveillance of CRA colonizations and infections identified from patients in CNISP-participating hospitals between 2010 and 2016. Methods Participating acute care facilities across Canada submitted CRAs from 1 January 2010 to 31 December 2016. Patient data were collected from medical records using a standardized questionnaire. WGS was conducted on all CRAs and data underwent single nucleotide variant analysis, resistance gene detection and MLST. Results The 7 year incidence rate of CRA was 0.02 per 10 000 patient days and 0.015 per 1000 admissions, with no significant increase observed over the surveillance period (P > 0.73). Ninety-four CRA isolates were collected from 58 hospitals, of which 93 (98.9%) were CPA. Carbapenemase OXA-235 group (48.4%) was the most common due to two separate clusters, followed by the OXA-23 group (41.9%). Patients with a travel history were associated with 38.8% of CRA cases. The all-cause 30 day mortality rate for infected cases was 24.4 per 100 CRA cases. Colistin was the most active antimicrobial agent (95.8% susceptibility). Conclusions CRA remains uncommon in Canadian hospitals and the incidence did not increase from 2010 to 2016. Almost half of the cases were from two clusters harbouring OXA-235-group enzymes. Previous medical treatment during travel outside of Canada was common.

P041: Trends in antiviral use in hospitalized patients following the 2009 influenza pandemic in Canada

receive antiviral treatment during the pandemic than during the post-pandemic seasons (89.7% vs. 75.7%, p<0.001). A higher proportion of adults admitted to the ICU during the 2009 pandemic (94.2%) received antiviral treatment compared with the 2010-11 and 2011-12 seasons (84.6%, p<0.001). There was no difference in antiviral treatment among inpatients who died within 30 days of admission during the pandemic (84.3%) than during the post-pandemic seasons (78.9%, p=0.370). Conclusion Antiviral treatment of adults hospitalized with laboratory-confirmed influenza significantly fell in the two seasons following the 2009 influenza pandemic. In order to guide strategies aimed at minimizing the impact of influenza among hospitalized adults, reasons for the decline in antiviral treatment need to be further explored.