High rates of Staphylococcus aureus USA400 infection, Northern Canada.

Surveillance of Staphylococcus aureus infections in 3 northern remote communities of Saskatchewan was undertaken. Rates of methicillin-resistant infections were extremely high (146-482/10,000 population), and most (98.2%) were caused by USA400 strains. Although USA400 prevalence has diminished in the United States, this strain is continuing to predominate throughout many northern communities in Canada.

Longitudinal phylogenetic surveillance identifies distinct patterns of cluster dynamics.

OBJECTIVE: Through the application of simple, accessible, molecular epidemiology tools, we aimed to resolve the phylogenetic relationships that best predicted patterns of cluster growth using longitudinal population level drug resistance genotype data. METHODS: Analysis was performed on 971 specimens from drug naïve, first time HIV positive subjects collected in British Columbia between 2002 and 2005. A 1240bp fragment of the pol gene was amplified and sequenced with relationships among subtype B sequences inferred using Neighbour-Joining analysis. Apparent clusters of infections having both a mean within group distance <0.031 and bootstrap value >80% were systematically identified. The entire 2002-2005 dataset was then re-analyze to evaluate the relationship of subsequent infections to those identified in 2002. BED testing was used to identify recent infections (<156 days). RESULTS: Among the 2002 infections, 136 of 300 sequences sorted into 52 clusters ranging in size from 2 to 9 members. Aboriginal ethnicity and intravenous drug use were correlated, and both were linked to cluster membership in 2002. Although cluster growth between 2002 and 2005 was correlated with the size of the original cluster, more related infections were found in clusters seeded from nonclustered infections. Finally, all large growth clusters were seeded from infections that were much more likely to be recent. CONCLUSIONS: This population level phylogenetic analysis suggests that a greater increase in cluster size is associated with recently infected individuals, which may represent the leading edge of the epidemic. The most impressive increase in cluster size is seen originating from initially nonclustered infections. In contrast, smaller existing clusters likely describe historical patterns of transmission and do not substantially contribute to the ongoing epidemic. Application of this method for cross-sectional analysis of existing sequences from defined geographic regions may be useful in predicting trends in HIV transmission.

Risk factors for and outcomes associated with clinical isolates of Escherichia coli and Klebsiella species resistant to extended-spectrum cephalosporins among patients admitted to Canadian hospitals.

BACKGROUND: Clinical features associated with Gram-negative bacterial isolates with extended-spectrum beta-lactamase (ESBL)- and AmpC-mediated resistance identified in Canadian hospitals is largely unknown. The objective of the present study was to determine the demographics, risk factors and outcomes of patients with ESBL- or AmpC-mediated resistant organisms in Canadian hospitals. METHODS: Patients with clinical cultures of Escherichia coli or Klebsiella species were matched with patients with a similar organism but susceptible to third-generation cephalosporins. Molecular identification of the AmpC or ESBL was determined using a combination of polymerase chain reaction and sequence analysis. Univariate and multivariate logistic regression analysis was performed to identify variables associated with becoming a case. RESULTS: Eight Canadian hospitals identified 106 cases (ESBL/AmpC) and 106 controls. All risk factors identified in the univariate analysis as a predictor of being an ESBL/AmpC cases at the 0.20 P-value were included in the multivariate analysis. No significant differences in outcomes were observed (unfavourable responses 17% versus 15% and mortality rates 13% versus 7%, P not significant). Multivariate logistic regression found an association of becoming an ESBL/AmpC case with: previous admission to a nursing home (OR 8.28, P=0.01) or acute care facility (OR 1.96, P=0.03), length of stay before infection (OR 3.05, P=0.004), and previous use of first-generation cephalosporins (OR 2.38, P=0.02) or third-generation cephalosporins (OR 4.52, P=0.01). Appropriate antibiotics were more likely to be given to controls (27.0% versus 13.3%, P=0.05) and number of days to appropriate antibiotics was longer for cases (median 2.8 days versus 1.2 days, P=0.05). CONCLUSION: The importance of patient medical history, present admission and antibiotic use should be considered for all E coli or Klebsiella species patients pending susceptibility testing results.

A cross-sectional study of maternity care providers' and women's knowledge, attitudes, and behaviours towards influenza vaccination during pregnancy.

BACKGROUND: Pregnant women are at increased risk of influenza-related complications, but research to examine barriers to maternal influenza vaccination has been limited and no studies have assessed the barriers to vaccinating pregnant women in Canada. OBJECTIVES: The objectives of the study were to assess (1) how the knowledge, attitudes, and beliefs of Canadian maternity care providers influence their discussion and recommendation patterns, and (2) how the knowledge, attitudes, and beliefs of Canadian women, along with care providers' recommendations, influence their acceptance of influenza vaccine during pregnancy. METHODS: Two cross-sectional surveys, one of maternity care providers and one of postpartum women, were carried out between December 1, 2003, and March 31, 2004. RESULTS: Multivariate logistic analysis demonstrated that high levels of provider knowledge about maternal vaccination (OR = 2.64; 95% CI 1.56-4.46), positive attitudes towards influenza vaccination (OR = 2.29; 95% CI 1.43-3.68), and increased age (OR = 1.03; 95% CI 1.02-1.06) were associated with recommending influenza vaccine to pregnant women. Similarly, women who had higher levels of knowledge about maternal vaccination (OR = 3.46; 95% CI 1.31-9.17), positive attitudes towards influenza vaccination (OR = 4.69; 95% CI 1.63-13.5), and a recommendation from their maternity care provider (OR = 32.3; 95% CI 10.4-100) were more likely to be vaccinated during pregnancy. One of the most striking provider barriers identified was uncertainty about who bears responsibility for discussion, recommendation, and vaccination. CONCLUSION: Maternity care provider recommendation was found to be an important element in increasing influenza vaccination rates during pregnancy. Clarity about responsibility for providing vaccine is needed.

Vancomycin-resistant enterococci in Canada: results from the Canadian nosocomial infection surveillance program, 1999-2005.

Surveillance for vancomycin-resistant enterococci (VRE) in sentinel Canadian hospitals has been conducted since 1999. From 1999 to 2005, the rate of VRE detection increased from 0.37 to 1.32 cases per 1,000 patients admitted, and the rate of VRE infection increased from 0.02 to 0.05 cases per 1,000 patients admitted. Thirty-three percent of all patients with VRE detected that were reported during 1999-2005 were identified in 2005, with increases seen in all regions of Canada. Although the incidence rate of VRE carriage in Canada is increasing, it remains very low.

Infection control and antimicrobial restriction practices for antimicrobial-resistant organisms in Canadian tertiary care hospitals.

In 2003, a survey examining infection control and antimicrobial restriction policies and practices for preventing the emergence and transmission of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE), and extended spectrum beta-lactamase (ESBL) was performed within Canadian teaching hospitals as part of the Canadian Nosocomial Infection Surveillance Program. Twenty-eight of 29 questionnaires were returned. The majority of facilities conducted admission screening for MRSA (96.4%) and VRE (89.3%) but only 1 site screened for ESBL/AmpC. Rates of MRSA, VRE, and ESBL remain low in Canada. It is believed that these lower rates may be due to intense admission screening protocols and stringent infection control policies for antimicrobial-resistant organisms (AROs) within Canadian institutions. Few (MRSA: 14.8%; VRE: 12.0%) recorded the number of patients screened. Regular prevalence surveys were done for MRSA (21.4%), VRE (35.7%), and ESBL/AmpC (3.8%). Pre-emptive precautions were applied for MRSA by 60.7% and for VRE by 75.0% of facilities. All facilities flagged patients previously identified with MRSA and VRE but only 46.2% flagged ESBL and 15.4% flagged AmpC patients. Barrier precautions varied by ARO and patient-care setting. In the inpatient non-ICU setting, more than 90% wore gowns and gloves for MRSA and VRE but only 50% for ESBL; and 57.1% wore masks for MRSA. Attempts to decolonize MRSA patients had been made by 82.1%, largely in order to place them in another facility. Policies restricting antimicrobial prescribing were reported by 21 facilities (75.0%). Further studies examining hospital infection control policies and corresponding rates of ARO infections would help in identifying and refining best practice guidelines within Canadian institutions.

A point prevalence survey of health care-associated infections in pediatric populations in major Canadian acute care hospitals.

OBJECTIVE: To estimate the prevalence of pediatric health care-associated infections (HAI) in Canadian acute care hospitals. METHODS: A point-prevalence study conducted in February 2002 in 25 hospitals across Canada. Information on HAI, utilization of antimicrobial agents and invasive devices, isolation precautions, and microbial etiology was collected. RESULTS: Nine hundred ninety-seven children were surveyed. Ninety-one HAI were detected in 80 patients for a prevalence of 91 per 1000 patients surveyed. Bloodstream infections were the most common HAI (3% of patients; 34% of all HAI). The prevalence of patients with HAI was 8%, ranging from 0% in trauma/bum units to 19% in the pediatric intensive care units, and 27% in transplant units. By multivariate logistic regression analysis, having a central venous catheter (OR, 2.54; 95% CI, 1.46-4.40) or endotracheal tube with mechanical ventilation (OR, 2.59; 95% CI, 1.16-5.76) were independently associated with an HAI, as were being in isolation (OR, 2.90; 95% CI, 1.54-5.45), and receiving antimicrobial agents (OR, 9.27; 95% CI, 4.71-18.52). CONCLUSION: In this first national point-prevalence study in Canada, the prevalence of HAI was similar to that reported in other industrialized countries. These data will also be useful to provide an estimate of the health burden of pediatric HAI in Canada.

ampC gene expression in promoter mutants of cefoxitin-resistant Escherichia coli clinical isolates.

Reverse transcriptase polymerase chain reaction was used to determine the amount of overexpression of the ampC gene in 52 cefoxitin-resistant Escherichia coli clinical isolates that had previously characterized mutations in their ampC promoter/attenuator regions. The results showed that mutations that create a consensus -35 box (TTGACA) are the most important factor in strengthening the ampC promoter, followed by base pair insertions that increase the distance between the -35 and -10 boxes to 17 or 18 bp. Mutations in the -10 box are of lesser importance and those in the attenuator region appear to have little effect on ampC expression. Three strains overexpress ampC due to the effect of insertion elements located in the ampC promoter regions. Further, the data show that there is no correlation between ampC overexpression and the minimum inhibition concentration of cefoxitin in clinical isolates. Overall, the data indicate that a combination of ampC promoter mutations and other strain-specific factors combine to contribute to the magnitude of cefoxitin resistance in E. coli.

Cluster of cases of severe acute respiratory syndrome among Toronto healthcare workers after implementation of infection control precautions: a case series.

OBJECTIVE: To review the severe acute respiratory syndrome (SARS) infection control practices, the types of exposure to patients with SARS, and the activities associated with treatment of such patients among healthcare workers (HCWs) who developed SARS in Toronto, Canada, after SARS-specific infection control precautions had been implemented. METHODS: A retrospective review of work logs and patient assignments, detailed review of medical records of patients with SARS, and comprehensive telephone-based interviews of HCWs who met the case definition for SARS after implementation of infection control precautions. RESULTS: Seventeen HCWs from 6 hospitals developed disease that met the case definition for SARS after implementation of infection control precautions. These HCWs had a mean age (+/-SD) of 39+/-2.3 years. Two HCWs were not interviewed because of illness. Of the remaining 15, only 9 (60%) reported that they had received formal infection control training. Thirteen HCWs (87%) were unsure of proper order in which personal protective equipment should be donned and doffed. Six HCWs (40%) reused items (eg, stethoscopes, goggles, and cleaning equipment) elsewhere on the ward after initial use in a room in which a patient with SARS was staying. Use of masks, gowns, gloves, and eyewear was inconsistent among HCWs. Eight (54%) reported that they were aware of a breach in infection control precautions. HCWs reported fatigue due to an increased number and length of shifts; participants worked a median of 10 shifts during the 10 days before onset of symptoms. Seven HCWs were involved in the intubation of a patient with SARS. One HCW died, and the remaining 16 recovered. CONCLUSION: Multiple factors were likely responsible for SARS in these HCWs, including the performance of high-risk patient care procedures, inconsistent use of personal protective equipment, fatigue, and lack of adequate infection control training.

Methicillin-resistant Staphylococcus aureus in Canadian aboriginal people.

We describe 279 hospitalized Canadian aboriginals in whom methicillin-resistant Staphylococcus aureus (MRSA) was detected. They were identified in 38 Canadian hospitals from 1995 through 2002. Compared with nonaboriginals, aboriginals were more likely to be younger than 18 years of age (OR, 1.8; P<.0001), to have had an MRSA infection (OR, 3.8; P<.0001), and to have had MRSA isolated from specimens of skin or soft tissue (OR, 4.1; P=.016). The clinical features of MRSA infection in aboriginals are distinct from those in the general patient population with MRSA infection in Canadian hospitals, and the genetic background of MRSA isolates from aboriginals also varies from that of strains from the non-aboriginal population.

Clinical and epidemiologic features of methicillin-resistant Staphylococcus aureus in elderly hospitalized patients.

We describe characteristics of elderly patients with MRSA identified in 37 Canadian hospitals between 1995 and 2002. Of these inpatients, 6,613 (66%) were older than 65 years. They were more likely than younger patients to have been colonized without infection and to have had MRSA isolated from urine or the perineum. The epidemiology and clinical features of these patients is distinct from that of younger patients.

Molecular characterization of cefoxitin-resistant Escherichia coli from Canadian hospitals.

A study designed to gain baseline information on strains of Escherichia coli displaying resistance to cefoxitin in Canada is described. A total of 29,323 E. coli isolates were screened at 12 participating hospital sites as part of an extended-spectrum beta-lactamase surveillance initiative. A total of 411 clinically significant, nonrepeat isolates displaying reduced susceptibilities to the NCCLS-recommended beta-lactams were submitted to a central laboratory over a 1-year period ending on 30 September 2000. Two hundred thirty-two isolates were identified as resistant to cefoxitin. All cefoxitin-resistant strains were subtyped by pulsed-field gel electrophoresis, and of these, 182 strains revealed a unique fingerprint and 1 strain was untypeable. PCR and sequence analysis of the ampC promoter region revealed 51 different promoter or attenuator variants and 14 wild-type promoters. Three promoter regions were interrupted by insertion elements, two contained IS10 elements, and one contained an IS911 variant. PCR and sequence analysis for the detection of acquired AmpC resistance (by the acquisition of ACT-1/MIR-1, CMY-2, or FOX) revealed that 25 strains contained CMY-2, including 7 of the strains found to have wild-type promoters. The considerable genetic variability in both the strain fingerprint and the promoter region suggests that AmpC-type resistance may emerge spontaneously by mutation of sensitive strains rather than by the spread of strains or plasmids in the hospital setting.

Ambler class A extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella spp. in Canadian hospitals.

This report describes a study carried out to gain baseline information on the molecular characteristics of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella spp. in Canada. A total of 29,323 E. coli and 5,156 Klebsiella sp. isolates were screened at 12 participating sites. Of these, 505 clinically significant, nonrepeat isolates displaying reduced susceptibility to the NCCLS-recommended beta-lactams were submitted to a central laboratory over a 1-year period ending on 30 September 2000. A total of 116 isolates were confirmed to be ESBL producers. PCR and sequence analysis revealed the presence of TEM-11 (n = 1), TEM-12 (n = 1), TEM-29 (n = 1), TEM-52 (n = 4), CTX-M-13 (n = 1), CTX-M-14 (n = 15), CTX-M-15 (n = 11), SHV-2 (n = 2), SHV-2a (n = 12), SHV-5 (n = 6), SHV-12 (n = 45), and SHV-30 (n = 2). Five novel beta-lactamases were identified and designated TEM-115 (n = 2), TEM-120 (n = 1), SHV-40 (n = 2), SHV-41 (n = 4), and SHV-42 (n = 1). In addition, no molecular mechanism was identified for five isolates displaying an ESBL phenotype. Macrorestriction analysis of all ESBL isolates was conducted, as was restriction fragment length polymorphism analysis of plasmids harboring ESBLs. Although a "clonal" distribution of isolates was observed at some individual sites, there was very little evidence suggesting intrahospital spread. In addition, examples of identical or closely related plasmids that were identified at geographically distinct sites across Canada are given. However, there was considerable diversity with respect to plasmid types observed.

Laboratory characterization of methicillin-resistant Staphylococcus aureus in Canadian hospitals: results of 5 years of National Surveillance, 1995-1999.

Two thousand seven hundred eighty single-patient, methicillin-resistant Staphylococcus aureus (MRSA) isolates collected between January 1995 and December 1999 at 17 tertiary care hospital sites across Canada were characterized by phenotypic and genotypic techniques. Six clonal types, as defined by pulsed-field gel electrophoresis, comprised 87% of all isolates and were labeled Canadian (C) MRSA-1 through -6. CMRSA-1 was the most prevalent clonal type, representing 45% of all MRSA. CMRSA-2 was indistinguishable from the New York clone and was more likely to be associated with community acquisition. CMRSA-3 was more likely to cause an infection, compared with the other CMRSA types. CMRSA-4 was indistinguishable from epidemic (E) MRSA-16 from the United Kingdom. Both CMRSA-5 and -6 occurred primarily in single-site, multiyear outbreaks. This study confirms that the epidemiology of MRSA in Canada is evolving, but most isolates at this time appear to belong to one of a small number of epidemic clones.

Morbidity, mortality, and healthcare burden of nosocomial Clostridium difficile-associated diarrhea in Canadian hospitals.

OBJECTIVE: To assess the healthcare burden, morbidity, and mortality of nosocomial Clostridium difficile-associated diarrhea (N-CDAD) in Canadian hospitals. DESIGN: Laboratory-based prevalence study. SETTING: Nineteen acute-care Canadian hospitals belonging to the Canadian Hospital Epidemiology Committee surveillance program. PATIENTS: Hospitalized patients in the participating centers. METHODS: Laboratory-based surveillance was conducted for C. difficile toxin in stool among 19 Canadian hospitals from January to April 1997, for 6 continuous weeks or until 200 consecutive diarrhea stool samples had been tested at each site. Patients with N-CDAD had to fulfill the case definition. Data collected for each case included patient demographics, length of stay, extent of diarrhea, complications of CDAD, CDAD-related medical interventions, patient outcome, and details of death. RESULTS: We found that 371 (18%) of 2,062 tested patients had stools with positive results for C difficile toxin, of whom 269 (13%) met the case definition for nosocomial CDAD. Of these, 250 patients (93%) had CDAD during their hospitalization, and 19 (7%) were readmitted because of CDAD (average readmission stay, 13.6 days). Forty-one patients (15.2%) died, of whom 4 (1.5% of the total) were considered to have died directly or indirectly of N-CDAD. The following N-CDAD-related morbidity was noted: dehydration, 3%; hypokalemia, 2%; gastrointestinal hemorrhage requiring transfusion, 1%; bowel perforation, 0.4%; and secondary sepsis, 0.4%. The cost of N-CDAD readmissions alone was estimated to be a minimum of $128,200 (Canadian dollars) per year per facility. CONCLUSION: N-CDAD is a common and serious nosocomial infectious complication in Canada, is associated with substantial morbidity and mortality, and imposes an important financial burden on healthcare institutions.