Device and surgical procedure-related infections in Canadian acute care hospitals, 2018–2022

Background Healthcare-associated infections (HAIs) are a significant healthcare burden in Canada. National surveillance of HAIs at sentinel acute care hospitals is conducted by the Canadian Nosocomial Infection Surveillance Program. Objective This article describes device and surgical procedure-related HAI epidemiology in Canada from 2018 to 2022. Methods Data were collected from over 60 Canadian sentinel acute care hospitals between January 1, 2018, and December 31, 2022, for central line-associated bloodstream infections (CLABSIs), hip and knee surgical site infections (SSIs), cerebrospinal fluid shunt (CSF) SSIs and paediatric cardiac SSIs. Case counts, rates, patient and hospital characteristics, pathogen distributions and antimicrobial resistance data are presented. Results Between 2018 and 2022, 2,258 device-related infections and 987 surgical procedure-related infections were reported. A significant rate increase was observed in adult mixed intensive care unit CLABSIs (1.07–1.93 infections per 1,000 line days, p=0.05) and a non-significant rate increase was observed in SSIs following knee arthroplasty (0.31–0.42 infections per 100 surgeries, p=0.45). A fluctuating rate trend was observed in CSF shunt SSIs over the time period and a significant rate decrease in paediatric cardiac SSIs was observed (68%, from 7.5–2.4 infections per 100 surgeries, p=0.01). The most commonly identified pathogens were coagulase-negative staphylococci (22.8%) among CLABSIs and Staphylococcus aureus (42%) among SSIs. Conclusion Epidemiological and microbiological trends among selected device and surgical procedure-related HAIs are essential for benchmarking infection rates nationally and internationally, identifying any changes in infection rates or antimicrobial resistance patterns and helping inform hospital infection prevention and control and antimicrobial stewardship policies and programs.


Introduction
Healthcare-associated infections (HAIs) contribute to excess patient morbidity and mortality, leading to increased healthcare costs, longer hospital stays and increased antimicrobial resistance (1).Healthcare-associated infections may occur during the use of invasive devices and following surgical procedures (2).
More specifically, surgical procedure-related infections are among the most prevalent HAIs and are responsible for a longer hospitalization of approximately seven to 11 days (3).Device and surgical procedure-related infections are also associated with a high-cost burden, accounting for almost $50,000 per central

Case definitions
Device and surgical procedure-related HAIs were defined according to standardized protocols and case definitions (see Appendix).Complex infections, defined as deep incisional and organ/space, were included in hip and knee SSI surveillance, while CLABSIs identified in intensive care unit (ICU) settings were included in CLABSI surveillance.The adult mixed ICU, adult cardiovascular surgery intensive care unit (CVICU), paediatric intensive care unit (PICU) and neonatal intensive care unit (NICU) were included as eligible ICU settings.Adult mixed intensive care units included any adult ICU with a mix of patient types as part of the ICU patient mix (i.e., medical/surgical, surgical/trauma, burn/ trauma, medical/neurosurgical).

Data source
Epidemiological data for device and surgical procedure-related infections identified between January 1, 2018, and December 31, 2022 (using surgery date for surgical site infections and date of positive blood culture for CLABSIs) were submitted by participating hospitals using standardized data collection forms.Hospital participation varied by surveillance project and year.Data submission and case identification were supported by training sessions and periodic evaluations of data quality.

Statistical analysis
To calculate hip and knee SSI, CSF shunt SSI and paediatric cardiac SSI rates, the number of cases were divided by the number of surgical procedures performed (multiplied by 100).To calculate CLABSI rates, the number of cases was divided by line day denominators (multiplied by 1,000).Neonatal intensive care unit CLABSI rates stratified by birth weight category were not included in this report.To calculate proportions of pathogens, the number of pathogens were divided by the total number of identified pathogens.Denominators may vary, as missing and incomplete data were excluded from analyses.Median and interquartile ranges (IQR) were calculated for continuous variables.Trends over time were tested using the Mann-Kendall test.Significance testing was two-tailed and differences were considered significant at a p-value of ≤0.05.Analyses were conducted using R version 4.1.2and SAS 9.4.

Results
Over 60 hospitals contributed device and surgical procedurerelated infection data to CNISP between 2018 and 2022 (Table 1), with medium-sized (n=201-499 beds) adult hospitals (n=16 sites, 25%) being the most common (data not shown).Overall, 2,258 device-related infections and 987 surgical procedure-related infections were reported.Among all SSIs reported (n=987), hip and knee infections represented 68% (n=667) of these types of infections.
A total of 2,496 pathogens were identified from device-related infections and 1,056 pathogens from surgical procedure-related cases between 2018 and 2022.Of the identified pathogens for CLABSIs, 61% were gram-positive, 24% were gram-negative and 15% were fungal.Of the identified pathogens for SSIs, 79% were gram-positive, 19% were gram-negative and 1.5% were fungal.Coagulase-negative staphylococci (CoNS) and Staphylococcus aureus were the most frequently reported pathogens for CLABSIs and SSIs, respectively (Table 2).From 2018 to 2022, the proportion of methicillin-resistant S. aureus (MRSA) was 16% for CLABSIs and 11% for SSIs (data not shown).
During the COVID-19 pandemic in 2020, knee SSI rates remained stable while hip SSI rates decreased by 40%, compared to 2019.
In 2022, both hip and knee SSI rates increased to 0.72 and 0.42 infections per 100 surgeries respectively, returning to rates observed in the pre-pandemic period (Figure 2 and Table A2).

SURVEILLANCE
with an SSI following hip or knee arthroplasty were readmitted and 66% (n=431/652) required revision surgery.Within 30 days after first positive culture, five all-cause deaths (2.1%, n=9/427) were reported among patients with a complex SSI following a hip arthroplasty while zero all-cause deaths were reported among patients with a knee arthroplasty SSI.Among hip and knee SSI cases, S. aureus and CoNS were the most commonly identified pathogens at 38% and 19%, respectively, and did not differ by deep or organ/space infection type (data not shown).

Cerebrospinal fluid shunt surgical site infections
Between 2018 and 2022, 151 CSF shunt SSIs were reported, with an overall rate of 2.9 infections per 100 surgeries (range: 1.7−3.82infections per 100 surgeries, Table A3).Paediatric and adult/mixed hospitals infection rates were not significantly different at 3.2 and 2.5 infections per 100 surgeries, respectively (p=0.17).Cerebrospinal fluid shunt SSI rates in all hospitals decreased throughout the COVID-19 pandemic in 2020 and 2021 (Figure 3

Paediatric cardiac surgical site infections
A total of 169 paediatric cardiac SSIs were reported between 2018 and 2022 (Table 4).Most of these SSIs were superficial infections (62%), followed by organ/space infections (30%).Overall, the average paediatric cardiac SSI rate was 3.9 infections per 100 surgeries (Table A4).From 2018 to 2022, rates decreased significantly by 68% and consistently, from 7.5 to 2.4 infections per 100 surgeries (p=0.01)(Figure 4).The high rate in 2018 was caused by outlier cases attributable to two hospitals.
The median age of patients with a paediatric cardiac SSI was 40 days (IQR=6-246 days) and the median time from surgery to onset date of infection was 16 days (IQR=8-24 days).Among the three deaths reported within 30 days of infection onset (1.8% of cases), one death was unrelated to the paediatric cardiac SSI, while two deaths were attributable to the paediatric cardiac SSI.Staphylococcus aureus and CoNS were the most commonly identified pathogens from paediatric cardiac SSIs (57% and 16% of identified pathogens, respectively) and did not differ by superficial, organ/space or deep infection type (data not shown).

Antibiogram
Results of antimicrobial susceptibility testing for the most frequently identified gram-positive, gram-negative and fungal pathogens from device and surgical procedure-related HAIs are listed in Figure 5

Staphylococcus aureus c
Streptococcus spp.

Staphylococcus aureus c
Streptococcus spp.c

Discussion
This report summarizes 2,258 device-related infections and 987 surgical procedure-related infections identified over five years of surveillance (2018-2022) from 64 hospitals across Canada.During this time, rates of device and surgical procedurerelated HAIs have increased significantly by 80% for adult mixed ICU CLABSIs and non-significantly by 36% for knee SSIs.The COVID-19 pandemic has had a varied impact on the rates of device and surgical procedure-related HAIs (10).In Canada, preliminary investigations suggest that the COVID-19 pandemic had an immediate but unsustained impact on HAI rate trends (11).Rates of SSIs in the CNISP network initially decreased in 2020 during the COVID-19 pandemic, when elective surgeries were postponed, before increasing towards pre-pandemic levels in 2021.Ongoing investigations continue to assess the influence of pandemic-related factors such as changes in infection control practices, screening, laboratory testing and antimicrobial stewardship on the observed rates of HAIs.

Central line-associated bloodstream infections
Where comparable data were available, the rates of CLABSI in adult ICUs (overall rate: 0.82 and 1.66 infections per 1,000 line days for CVICUs and mixed ICUs, respectively) were lower than those in the United Kingdom but higher than those in Western Australia (12)(13)(14).In the United Kingdom, 2021 and 2022 rates of CLABSI in the adult and cardiac ICU were 2.5 and 1.6 infections per 1,000 line days, respectively (14).In Western Australia, CLABSI rates in adult ICU settings ranged from 0.0 to 0.8 infections per 1,000 line days between 2018 and 2022 and may be lower than levels in Canada due to differences in surveillance methodologies including the number and type of hospitals under surveillance (12)

Surgical site infections
Among SSIs included in this surveillance report, hip and knee SSIs were the most prevalent.Hip SSI rates fluctuated across reporting years, while knee SSI rates increased non-significantly.Surveillance from the United Kingdom indicates hip and knee SSI rates slightly increased for 2021 and 2022, after remaining stable for 10 years (22).Compared to CNISP data, hip and knee SSI rates reported in Southern Australia were higher overall and have also seen increases in recent years; hip SSI rates increased from 2018 to 2020 (1.80-1.91 infections per 100 procedures), while knee SSI rates increased from 0.79 to 0.88 infections per 100 procedures, during the same time period (23).In accordance with results from other regions, the most common pathogens among hip and knee SSIs were S. aureus and CoNS, likely attributed to the contamination of implant devices by the patient's endogenous skin flora (24,25) The overall rate of paediatric cardiac SSI between 2018 and 2022 was 3.93 per 100 surgeries.The relatively high rate of paediatric cardiac SSI in 2018 should be interpreted with caution, as rates may fluctuate due to the limited number of annual cases.Literature regarding paediatric cardiac SSI rates is limited; however, a pre-post intervention study from 2013 to 2017 has reported successful reduction in paediatric cardiac SSI rates from 3.4 to 0.9 per 100 surgeries in a quaternary, paediatric academic center in California following the implementation of a postoperative SSI reduction care bundle (34).

Antibiogram
The percentage of S. aureus isolates that were MRSA among CLABSIs (15%) and SSIs (12%) was lower in the CNISP network compared to data reported by Centers for Disease Control and Prevention where 44% and 38% of S. aureus isolates were MRSA for CLABSIs and SSIs, respectively (35).

Strengths and limitations
The main strength of CNISP surveillance is the standardized collection of detailed epidemiological and molecular linked data from a large representative network of sentinel hospitals across Canada.From 2018 to 2022, CNISP coverage of Canadian acute care beds has increased from 32% to 35%, including increased representativeness in northern, community, rural, and Indigenous populations.To further improve representativeness, CNISP has launched a simplified dataset accessible to all acute care hospitals across Canada to collect and visualize annual HAI rate data.The number of hospitals participating in each HAI surveillance project differed and epidemiologic data collected were limited to the information available in the patient charts.
For CLABSI surveillance, data were limited to infections occurring in the ICU settings, and as such may only represent a subset of CLABSIs occurring in the hospital.Further, differences in surveillance protocols and case definitions limit comparison with data from other countries.Studies are ongoing to assess the impact of the COVID-19 pandemic on device and surgical procedure-related HAIs and antimicrobial resistance.

Conclusion
This report provides an updated summary of rates, pathogen distributions and antimicrobial resistance patterns among select device and surgical procedure-related HAIs and relevant pathogens.The collection and analysis of national surveillance data are important to understanding and reducing the burden of device and surgical procedure-related HAIs.These data provide benchmark rates for national and international comparison and inform antimicrobial stewardship and infection prevention and control programs and policies.

Appendix: Case definitions Central line-associated bloodstream infection
Only central line-associated bloodstream infections (CLABSIs) related to an intensive care unit (ICU) admission were included in surveillance.

Bloodstream infections case definition:
Bloodstream infection is NOT related to an infection at another site and it meets one of the following criteria: Criterion 1: Recognized pathogen cultured from at least one blood culture, unrelated to infection at another site.
OR Criterion 2: At least one of: fever (higher than 38°C core), chills, hypotension; if aged younger than 1 year, fever (higher than 38°C core), hypothermia (lower than 36°C core), apnea or bradycardia AND common skin contaminant (see list below) cultured from at least two blood cultures drawn on separate occasions or at different sites, unrelated to infection at another site.Different sites may include peripheral veins, central venous catheters or separate lumens of a multilumen catheter.Different times include two blood cultures collected on the same or consecutive calendar days via separate venipunctures or catheter entries.
The collection date of the first positive blood culture is the date used to identify the date of positive culture.Two positive blood culture bottles filled at the same venipuncture or catheter entry constitute only one positive blood culture.

Central line-associated bloodstream infection case definition:
A CLABSI must meet one of the following criteria: Criterion 1: A laboratory-confirmed bloodstream infection (LCBSI) where a central line catheter (CL) or umbilical catheter (UC) was in place for more than two calendar days on the date of the positive blood culture, with day of device placement being Day 1.

OR Criterion 2:
A LCBSI where a CL or UC was in place more than two calendar days and then removed on the day or one day before positive blood culture was drawn.

Intensive care unit-related central line-associated bloodstream infection case definition:
A CLABSI related to an ICU if it meets one of the following criteria: Criterion 1: CLABSI onset after two days of ICU stay.

OR
Criterion 2: If the patient is discharged or transferred out of the ICU, the CLABSI would be attributable to the ICU if it occurred on the day of transfer or the next calendar day after transfer out of the ICU.
Note: If the patient is transferred into the ICU with the CL and the blood culture was positive on the day of transfer or the next calendar day, then the CLABSI would be attributed to the unit where the line was inserted.

Hip and knee surgical site infection
Only complex surgical site infections (SSIs) (deep incisional or organ/space) following hip and knee arthroplasty were included in surveillance.
A deep incisional surgical site infection must meet the following criterion: Infection occurs within 90 days after the operative procedure and the infection appears to be related to the operative procedure and involves deep soft tissues (e.g., facial and muscle layers) of the incision and the patient has at least ONE of the following: • Purulent drainage from the deep incision but not from the organ/space component of the surgical site • Deep incision that spontaneously dehisces or is deliberately opened by the surgeon and is culture-positive or not cultured when the patient has at least one of the following signs or symptoms: fever (higher than 38°C) or localized pain or tenderness (a culture-negative finding does not meet this criterion)

SURVEILLANCE
An organ/space surgical site infection must meet the following criterion: Infection occurs within 90 days after the operative procedure and the infection appears to be related to the operative procedure and infection involves any part of the body, excluding the skin incision, fascia or muscle layers, that is opened or manipulated during the operative procedure and patient has at least ONE of the following: • Purulent drainage from a drain that is placed through a stab wound into the organ/space • Organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space • An abscess or other evidence of infection involving the organ/space that is found on direct examination, during reoperation or by histopathologic or radiologic examination • Diagnosis of an organ/space SSI by a surgeon or attending physician

Cerebrospinal fluid shunt surgical site infection
Only patients who underwent a placement or revision of a cerebrospinal fluid (CSF) shunting device and the infection occurred within one year of surgery were included in surveillance.
Cerebrospinal fluid shunt-associated surgical site infection case definition: An internalized CSF shunting device is in place AND a bacterial or fungal pathogen(s) is identified from the cerebrospinal fluid AND is associated with at least ONE of the following: • Fever (temperature 38°C or higher) • Neurological signs or symptoms • Abdominal signs or symptoms • Signs or symptoms of shunt malfunction or obstruction

Paediatric cardiac surgery surgical site infection
Only surgical site infections following open-heart surgery with cardiopulmonary bypass among paediatric patients (younger than 18 years of age) were included in surveillance.
A superficial incisional SSI must meet the following criterion: Infection occurs within 30 days after the operative procedure and involves only skin and subcutaneous tissue of the incision and meets at least ONE of the following criteria: • Purulent drainage from the superficial incision • Organisms isolated from an aseptically obtained culture of fluid or tissue from the superficial incision • At least ONE of the following signs or symptoms of infection: • Pain or tenderness, localized swelling, redness or heat, and the superficial incision is deliberately opened by a surgeon, and is culture-positive or not cultured (a culturenegative finding does not meet this criterion) • Diagnosis of superficial incisional SSI by the surgeon or attending physician A deep incisional SSI must meet the following criterion: Infection occurs within 90 days after the operative procedure and the infection appears to be related to the operative procedure AND involves deep soft tissues (e.g., facial and muscle layers) of the incision AND the patient has at least ONE of the following: • Purulent drainage from the deep incision but not from the organ/space component of the surgical site • Deep incision spontaneously dehisces or is deliberately opened by the surgeon and is culture-positive or not cultured when the patient has at least one of the following signs or symptoms: fever (higher than 38°C) or localized pain or tenderness (a culture-negative finding does not meet this criterion) • An abscess or other evidence of infection involving the deep incision is found on direct examination, during reoperation or by histopathologic or radiologic examination • Diagnosis of a deep incisional SSI by a surgeon or attending physician An organ/space SSI must meet the following criterion: Infection occurs within 90 days after the operative procedure and the infection appears to be related to the operative procedure AND infection involves any part of the body, excluding the skin incision, fascia or muscle layers, that is opened or manipulated during the operative procedure AND the patient has at least ONE of the following: • Purulent drainage from a drain that is placed through a stab wound into the organ/space • Organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space • An abscess or other evidence of infection involving the organ/space that is found on direct examination, during reoperation or by histopathologic or radiologic examination

Figure 5 :
Figure 5: Antibiogram results a from pathogens identified from central line-associated bloodstream infections, 2018-2022 b,c,d,e parapsilosis A m o x ic il li n / c la v u la n ic a c id A m p ic il li n B e n z y lp e n ic il li n C e fa z o li n C e ft ri a x o n e C ip ro fl o x a c in C li n d a m y c in C lo x a c il li n / o x a c il li n D a p to m y c in E rt a p e n e m E ry th ro m y c in G e n ta m ic in d L in e z o li d M e ro p e n e m P ip e ra c il li n / ta z o b a c ta m R if a m p ic in T e tr a c y c li n e T o b ra m y c in T ri m e th o p ri m / su lf a m e th o x a z o le V a n c o m y c in A m p h o te ri c in B C a sp o fu n g in F lu c o n a z o le M ic a fu n g in V o ri c o n a z o le ic il li n B e n z y lp e n ic il li n C e f a z o li n C e f t r ia x o n e C ip r o fl o x a c in C li n d a m y c in D a p t o m y c in E r t a p e n e m E r y t h r o m y c in G e n t a m ic in d L in e z o li d M e r o p e n e m P ip e r a c il li n / t a z o b a c t a m R if a m p ic in T e t r a c y c li n e T o b r a m y c in T

Figure 6 :
Figure 6: Antibiogram results a from pathogens identified from hip and knee, cerebrospinal fluid shunt and paediatric cardiac surgical site infections, 2018-2022 b,c,d,e

Table 1 :
Characteristics of acute care hospitals participating in device and surgical procedure-related healthcare-associated infection surveillance, 2022 Abbreviations: CLABSI, central line-associated bloodstream infection; CSF shunt SSI, cerebrospinal fluid shunt surgical site infection; CVICU, cardiovascular surgery intensive care unit; ICU, intensive care unit; N/A, not applicable; NICU, neonatal intensive care unit; PICU, paediatric intensive care unit; SSI, surgical site infection a Four hospitals classified as "adult" also had a NICU

Table 3 :
Frequency of hip and knee surgical site infections by year and infection type, 2018-2022 Figure 1: Rate of central line-associated bloodstream infection per 1,000 line days by intensive care unit type, 2018-2022 Abbreviations: CVICU, cardiovascular intensive care unit; ICU, intensive care unit; NICU, neonatal intensive care unit; PICU, paediatric intensive care unit

Table 4 :
Paediatric cardiac surgical site infection rates by year and infection type, 2018-2022 (27)(28)(29)(30)age of patients with hip and knee SSIs relate to the older age of patients requiring joint replacements and the increased likelihood of surgical complications(26).Our data indicate that frequent readmission and revision surgeries are required for SSIs, both of which place high economic and resource burdens on the Canadian healthcare system, consistent with other studies from the United States, Australia and the United Kingdom(27)(28)(29)(30).
(38,39)identified Enterococcus spp. in CLABSIs, 23% were vancomycin-resistant Enterococci (VRE).From National Healthcare Safety Network surveillance in the United States, 73% of Enterococcus faecium and 4% of Enterococcus faecalis pathogens identified from CLABSIs in ICUs were VRE in 2021(36).Meropenem resistance was low in most gram-negative pathogens identified among CLABSIs and SSIs (0%-8%) in the CNISP network, and similar to carbapenem resistance levels reported in the United States in 2021 (5% among Klebsiella spp.; 6% among Enterobacter spp.; and 0.8% among tested E. coli isolates) (37).However, among Pseudomonas spp.identified in CLABSIs, meropenem resistance was 38%, which is higher than levels reported in the United States (21% carbapenem-resistant Pseudomonas aeruginosa among CLABSIs in 2021)(38,39).Overall, antibiogram patterns observed in the CNISP network may differ compared to other countries due to differences in surveillance methodologies, antimicrobial stewardship practices, types of hospitals or patient populations under surveillance and differences in circulating molecular strain types.
• An abscess or other evidence of infection involving the deep incision is found on direct examination, during reoperation or by histopathologic or radiologic examination • Diagnosis of a deep incisional SSI by a surgeon or attending physician Page 209 CCDR • June 2024 • Vol.50 No.6

Table A1 :
Rate of central line-associated bloodstream infection per 1,000 line days by intensive care unit type, 2018-2022 : CVICU, cardiovascular intensive care unit; ICU, intensive care unit; NICU, neonatal intensive care unit; PICU, paediatric intensive care unit Abbreviations

Table A2 :
Rate of hip and knee surgical site infections per 100 surgeries, 2018-2022

Table A3 :
Cerebrospinal fluid shunt surgical site infection rates per 100 surgeries by hospital type, 2018-2022 All hospitals include adult, mixed, and paediatric hospitals participating in cerebrospinal fluid shunt surgical site infection surveillance a