Sources of viral respiratory infections in Canadian acute care hospital healthcare personnel.

BACKGROUND: Viral respiratory illnesses are common causes of outbreaks and can be fatal to some patients. AIM: To investigate the association between laboratory-confirmed viral respiratory infections and potential sources of exposure during the previous 7 days. METHODS: In this nested case-control analysis, healthcare personnel from nine Canadian hospitals who developed acute respiratory illnesses during the winters of 2010/11-2013/14 submitted swabs that were tested for viral pathogens. Associated illness diaries and the weekly diaries of non-ill participants provided information on contact with people displaying symptoms of acute respiratory illness in the previous week. Conditional logistic regression assessed the association between cases, who were matched by study week and site with controls with no respiratory symptoms. FINDINGS: There were 814 laboratory-confirmed viral respiratory illnesses. The adjusted odds ratio (aOR) of a viral illness was higher for healthcare personnel reporting exposures to ill household members [7.0, 95% confidence interval (CI) 5.4-9.1], co-workers (3.4, 95% CI 2.4-4.7) or other social contacts (5.1, 95% CI 3.6-7.1). Exposures to patients with respiratory illness were not associated with infection (aOR 0.9, 95% CI 0.7-1.2); however, healthcare personnel with direct patient contact did have higher odds (aOR 1.3, 95% CI 1.1-1.6). The aORs for exposure and for direct patient contact were similar for illnesses caused by influenza. CONCLUSION: Community and co-worker contacts are important sources of viral respiratory illness in healthcare personnel, while exposure to patients with recognized respiratory infections is not associated. The comparatively low risk associated with direct patient contact may reflect transmission related to asymptomatic patients or unrecognized infections.

Relationship between enteric pathogens and acute gastroenteritis disease severity: a prospective cohort study.

OBJECTIVES: To evaluate the relationship between individual bacterial and viral pathogens and disease severity. METHODS: Children <18 years with three or more episodes of vomiting and/or diarrhoea were enrolled in two Canadian paediatric emergency departments between December 2014 and August 2016. Specimens were analysed employing molecular panels, and outcome data were collected 14 days after enrolment. The primary outcome was severe disease over the entire illness (symptom onset until 14-day follow-up), quantified employing the Modified Vesikari Scale (MVS) score. The score was additionally analysed in two other time periods: index (symptom onset until enrolment) and follow-up (enrolment until 14-day follow-up). RESULTS: Median participant age was 20.7 (IQR: 11.3, 44.2) months; 47.4% (518/1093) and 73.4% (802/1093) of participants had index and total MVS scores ≥11, respectively. The most commonly identified pathogens were rotavirus (289/1093; 26.4%) and norovirus (258/1093; 23.6%). In multivariable analysis, severe disease over the entire illness was associated with rotavirus (OR = 9.60; 95%CI: 5.69, 16.19), Salmonella (OR = 6.61; 95%CI: 1.50, 29.17), adenovirus (OR = 2.53; 95%CI: 1.62, 3.97), and norovirus (OR = 1.43; 95%CI: 1.01, 2.01). Pathogens associated with severe disease at the index visit were: rotavirus only (OR = 6.13; 95%CI: 4.29, 8.75), Salmonella (OR = 4.59; 95%CI: 1.71, 12.29), adenovirus only (OR = 2.06; 95%CI: 1.41, 3.00), rotavirus plus adenovirus (OR = 3.15; 95%CI: 1.35, 7.37), and norovirus (OR = 0.68; 95%CI: 0.49, 0.94). During the follow-up period, rotavirus (OR = 2.21; 95%CI: 1.50, 3.25) and adenovirus (OR = 2.10; 95%CI: 1.39, 3.18) were associated with severe disease. CONCLUSIONS: In children presenting for emergency department care with acute gastroenteritis, pathogens identified were predominantly viruses, and several of which were associated with severe disease. Salmonella was the sole bacterium independently associated with severe disease.

Unusual Legionnaires' outbreak in cool, dry Western Canada: an investigation using genomic epidemiology.

An outbreak of Legionnaires' disease occurred in an inner city district in Calgary, Canada. This outbreak spanned a 3-week period in November-December 2012, and a total of eight cases were identified. Four of these cases were critically ill requiring intensive care admission but there was no associated mortality. All cases tested positive for Legionella pneumophila serogroup 1 (LP1) by urinary antigen testing. Five of the eight patients were culture positive for LP1 from respiratory specimens. These isolates were further identified as Knoxville monoclonal subtype and sequence subtype ST222. Whole-genome sequencing revealed that the isolates differed by no more than a single vertically acquired single nucleotide variant, supporting a single point-source outbreak. Hypothesis-based environmental investigation and sampling was conducted; however, a definitive source was not identified. Geomapping of case movements within the affected urban sector revealed a 1·0 km common area of potential exposure, which coincided with multiple active construction sites that used water spray to minimize transient dust. This community point-source Legionnaires' disease outbreak is unique due to its ST222 subtype and occurrence in a relatively dry and cold weather setting in Western Canada. This report suggests community outbreaks of Legionella should not be overlooked as a possibility during late autumn and winter months in the Northern Hemisphere.

Surveillance summary of hospitalized pediatric enterovirus D68 cases in Canada, September 2014.

BACKGROUND: Enterovirus D68 (EV-D68) has been detected infrequently and has not been associated with severe disease in Canada. In the early fall of 2014, following an unusual case increase in the United States, clusters of EV-D68 among children and some adults manifesting severe symptoms were reported in Canada. OBJECTIVE: To provide an initial epidemiological summary of pediatric cases hospitalized with EV-D68 in Canada. METHODS: A time-limited surveillance pilot was conducted collecting information on pediatric cases (less than 18 years of age) hospitalized with EV-D68 between September 1 and 30, 2014. RESULTS: In total, 268 cases were reported from Ontario (n=210), Alberta (n=45), and British Columbia (n=13). Of the 268 reported cases, 64.9% (n=174) were male; the sex difference was statistically significant (p<0.01). Age was reported for 255 cases, with a mean age for males of 5.4 years and for females of 5.3 years. For cases with data available, 6.8% (18/266) were admitted to an intensive care unit. Of those where clinical illness was recorded, respiratory illness alone was present in 98.3% (227/231), neurologic illness alone was present in 0.4% (n=1), and both illnesses were present in 0.9% of cases (n=2); cases with neither respiratory nor neurologic illness were rare (n=1). Of the 90 cases with additional clinical information available, 43.3% were reported as having asthma. No deaths were reported among the 268 cases. CONCLUSION: The EV-D68 outbreak in Canada in September 2014 represents the beginning of a novel outbreak associated with severe illness in children. These findings provide the first epidemiological summary of severe cases of EV-D68 as an emergent respiratory pathogen in Canada. The continued investigation of this pathogen is necessary to build on these results and capture the full spectrum of associated illness.

Surveillance and molecular characterization of non-tuberculous mycobacteria in a hospital water distribution system over a three-year period.

A three-year surveillance of non-tuberculous mycobacteria (NTM) in a hospital water distribution system was conducted at a facility located in southern Alberta. NTM was not present in any intake water samples, but was found in 106/183 (58%) of endpoint samples across 15 sites over the study period. Two different species of NTM were identified, Mycobacterium gordonae (88/183) and Mycobacterium avium (34/183); with only one strain of each M. gordonae and M. avium found. Given the sensitive nature of a healthcare facility, attention should be paid to minimize potential impact of NTM from potable water sources on patient health.

Prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) in food samples associated with foodborne illness in Alberta, Canada from 2007 to 2010.

Consumption of foods containing Staphylococcus aureus can cause severe gastro-intestinal illness. Given the fact that over the past decade, Canada has seen increasing rates of methicillin-resistant S. aureus (MRSA) carriage and infection, the objective of this study was to investigate the impact of methicillin-susceptible S. aureus (MSSA) and MRSA on foodborne illness in Alberta, Canada. Between January 2007 and December 2010, there were 693 food samples associated with foodborne investigations submitted to the Alberta Provincial Laboratory for Public Health (ProvLab). These foods were screened for: Bacillus cereus, Clostridium perfringens, S. aureus, Aeromonas spp., Campylobacter spp., Escherichia coli O157:H7, Salmonella, Shigella spp., and Yersinia spp. S. aureus was identified in 10.5% (73/693) of samples, and of these, 59% (43/73) were co-contaminated with at least one other organism on the screening panel. The S. aureus positive samples included 29 meat, 20 prepared foods containing meat, 11 prepared foods not containing meat, 10 dairy, and three produce. Methicillin-resistance was not detected in any isolates tested. These findings indicate that the presence of S. aureus in food associated with foodborne investigations is a cause for concern, and although MRSA was not found, the potential for outbreaks exists, and ongoing surveillance should be sustained.

Evaluation of multiple commercial molecular and conventional diagnostic assays for the detection of respiratory viruses in children.

This study compares the performance of four commercial multiplex PCR assays (Resplex II Panel v2.0, Seeplex RV15, xTAG RVP and xTAG RVP Fast) and direct fluorescent antibody (DFA) staining and viral isolation. Seven hundred and fifty nasopharyngeal swabs were tested for 17 viral agents. In each assay, the sensitivity and specificity for each target were determined against a composite reference standard. Two hundred and eighty-eight out of 750 (38.4%) specimens were positive by DFA or viral isolation, while an additional 214 (28.5%) were positive by multiplex PCR, for a total positivity rate of 66.9%. Of 502 positive specimens, one virus was detected in 420 specimens (83.7%), two in 77 (15.3%), three in four (0.8%) and four in one case (0.2%). Compared with a composite reference standard, the inter-assay accuracy of the multiplex PCR assays varied, but all were superior to conventional diagnostic methods in detecting a broad range of respiratory viral agents in children. In addition, the sensitivity of two commercial assays, Resplex II Plus PRE and Seeplex Influenza A/B Subtyping, was determined relative to the Astra influenza Screen & Type assay for detection of influenza A viruses, including seasonal influenzas and pandemic H1N1 2009 influenza A virus. Using 75 positive and 55 negative nasopharyngeal swabs for influenza A by the Astra assay, the sensitivity of Seeplex and Resplex was 95.9% and 91.8%, respectively, with a specificity of 100% for both.

Surveillance of autopsy cases for D222G substitutions in haemagglutinin of the pandemic (H1N1) 2009 virus in Alberta, Canada.

Pandemic (H1N1) 2009 virus-positive specimens were collected from autopsy patients and matched to pandemic (H1N1) 2009 virus-positive nasopharyngeal specimens from community control patients and pandemic (H1N1) 2009 virus-positive specimens from intensive-care unit (ICU) patients. Specimens were analysed for polymorphisms at amino acid 222 of the haemagglutinin (HA) glycoprotein. Whereas some specimens from autopsy patients were positive for D222N, none was positive for D222G. All control patient specimens were wild-type D222. D222G polymorphisms were also identified in a subset of ICU patients with admixtures of D222G and D222 and of D222N, D222G and D222 present. The relevance of D222N and D222G to influenza pathogenesis and transmissibility currently remains unclear.

Novel duplex real-time PCR assay detects Bordetella holmesii in specimens from patients with Pertussis-like symptoms in Ontario, Canada.

Bordetella holmesii is a human pathogen found mainly in immunocompromised patients. A specific real-time PCR assay was developed and successfully used to identify specimens from which B. holmesii was misidentified as Bordetella pertussis and to establish the prevalence of B. holmesii in Ontario patients with pertussis-like symptoms.

Development of a novel real-time reverse-transcriptase PCR method for the detection of H275Y positive influenza A H1N1 isolates.

During the 2007-2008 influenza season global strain surveillance for antiviral resistance revealed the sudden emergence of oseltamivir resistance in influenza A H1N1 isolates. Although oseltamivir resistance rates vary from region to region, 16% of isolates tested globally were found to be oseltamivir resistant by a histidine to tyrosine mutation of residue 275 of the neuraminidase gene of influenza A. In order to implement effective resistance testing locally a novel real-time reverse-transcriptase PCR (RT-PCR) assay was developed for the detection of the H275Y mutation. To evaluate this method, 40 oseltamivir resistant and 61 oseltamivir sensitive H1N1 influenza isolates were tested using Sanger sequencing, which is the reference method for detection of resistance, pyrosequencing and the novel H275Y RT-PCR assay. In comparison to Sanger sequencing, the sensitivity and specificity of the H275Y RT-PCR assay were 100% (40/40) and 100% (61/61) respectively, while the sensitivity and specificity of pyrosequencing were 100% (40/40) and 97.5% (60/61) respectively. Although all three methods were effective in detecting the H275Y mutation associated with oseltamivir resistance, the H275Y RT-PCR assay was the most rapid and could easily be incorporated into an influenza subtyping protocol.

Genetic microheterogeneity of emerging H275Y influenza virus A (H1N1) in Toronto, Ontario, Canada from the 2007-2008 respiratory season.

BACKGROUND: The H275Y mutation (H274Y in N2 numbering) in the neuraminidase (NA) gene (segment 6) of the influenza virus A (H1N1) genome is linked to oseltamivir resistance. OBJECTIVES: To determine the percentage of influenza virus A (H1N1) isolates that carry the H275Y mutation in the NA gene in Toronto, Ontario, Canada and to characterize select oseltamivir resistant and susceptible isolates using sequence analysis. STUDY DESIGN: Sanger sequencing was used to determine strain type and H275Y mutations based on partial sequencing of the hemagglutinin (HA) (segment 4) and NA genes. Mutations in the NS1 gene (segment 8) were determined by Sanger sequencing and pyrosequencing. Statistical analysis of demographics and proportions of H275 and H275Y isolates with mutations was carried out using chi(2) analyses. RESULTS: The HA gene of influenza virus A (H1N1) isolates collected during the 2007-2008 respiratory season was most like influenza A/Brisbane/59/2007, Clade 2, subclade B. Seventeen percent of these isolates possessed the H275Y NA mutation associated with oseltamivir resistance. H275Y isolates were more likely than H275 isolates to have the mutations A209T and R224G in NS1 (chi(2)=284.9, df=2, p<0.0001). CONCLUSIONS: During the 2007-2008 influenza season in Toronto, Ontario, Canada, 17% of influenza virus A (H1N1) isolates carried the H275Y mutation associated with oseltamivir resistance. These H275Y isolates were more likely than H275 isolates to exhibit unique microheterogeneity in the gene encoding the NS1 protein.

Differential patterns of amantadine-resistance in influenza A (H3N2) and (H1N1) isolates in Toronto, Canada.

BACKGROUND: Molecular methods were used to characterize influenza A (H1N1) and (H3N2) strains and to identify amantadine-resistance. OBJECTIVES: To compare proportions of amantadine-resistant influenza A (H1N1) and (H3N2) isolates in the Greater Toronto Area. STUDY DESIGN: Isolates of influenza A (H1N1) and (H3N2) were strain typed using molecular methods. Pyrosequencing for point mutations in the transmembrane domain of the M2 proton channel was undertaken. Proportions of amantadine-resistant and susceptible isolates were compared using the The Fisher's exact test. RESULTS: 96% of the 49 influenza A (H3N2) isolates and none of the influenza A (H1N1) tested carried a point mutation in the M gene coding for the M2 protein. Influenza A (H3N2) isolates were more likely to carry an amantadine-resistance associated mutation than influenza A (H1N1) isolates (Fishers's exact test, P<0.0001). CONCLUSIONS: : Characterization of amantadine-resistance in influenza A (H1N1) isolates should utilize a variety of different methods including sub-typing, strain typing, and direct sequencing for point mutations associated with amantadine-resistance.

Use of Bordetella pertussis BP3385 to establish a cutoff value for an IS481-targeted real-time PCR assay.

This study utilized the Bordetella pertussis single-copy PCR target BP3385 as a means of confirming IS481 PCR-positive reactions with cycle threshold (C(T)) values of >35. IS481 PCRs with C(T) values of >35 cycles may represent PCR conditions where there is <1 CFU of B. pertussis per PCR.

Decreased prevalence of virulence factors among ciprofloxacin-resistant uropathogenic Escherichia coli isolates.

Ciprofloxacin resistance was identified in 18% and 6% of consecutively collected, clinically significant urinary tract isolates of Escherichia coli from inpatients and outpatients, respectively. In comparison to ciprofloxacin-susceptible isolates, there were fewer resistant isolates that expressed beta-hemolysis (outpatient, 9% versus 87%, P < 0.0001; inpatient, 4% versus 76%, P < 0.0001) and that had a papEF genotype, genes encoding P fimbriae (outpatient, 30% versus 70%, P = 0.0004; inpatient, 26% versus 70%, P < 0.0001).

A protein kinase inhibitor as an antimycobacterial agent.

The protein kinase inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) was found to inhibit the growth of two different mycobacterial strains, the slow-growing Mycobacterium bovis Bacille Calmette Guerin (BCG) and the fast-growing saprophyte Mycobacterium smegmatis mc2 155, in a dose-dependent manner. While screening for the effect of kinase inhibitors on mycobacterial growth, millimolar concentrations of H7 induced a 40% decrease in the growth of M. bovis BCG when measured as a function of oxidative phosphorylation. This H7-induced decrease in growth was shown to involve a 2-log fold decrease in the viable counts of M. smegmatis within a 48-h period and a 50% reduction in the number of BCG viable counts within a 10-day period. Micromolar concentrations of H7 compound induced a significant decrease in the activity of the Mycobacterium tuberculosis protein serine/threonine kinase (PSTK) PknB. The inhibition of mycobacterial growth as well as the inhibition of a representative M. tuberculosis protein serine/threonine kinase PknB suggests that conventional PSTK inhibitors can be used to study the role that the mycobacterial PSTK family plays in controlling bacterial growth.

Expression and characterization of the Mycobacterium tuberculosis serine/threonine protein kinase PknB.

PknB is a member of the newly discovered eukaryotic-like protein serine/threonine kinase (PSTK) family of proteins. The pknB gene was cloned and expressed in Escherichia coli. The active recombinant protein was purified and shown to be reactive with antiphosphoserine antibodies, as well as with antibodies to the phosphorylated eukaryotic Ser/Thr kinases mitogen-activated protein kinase kinase 3 and 6, P38, and Creb. In vitro kinase assays demonstrated that PknB is a functional kinase that is autophosphorylated on serine/threonine residues and is also able to phosphorylate the peptide substrate myelin basic protein. Analysis of pknB expression in Mycobacterium tuberculosis indicates the presence of pknB mRNA in (i) organisms grown in vitro in bacteriological media, (ii) a murine macrophage in vitro infection model, and (iii) in vivo alveolar macrophages from a patient with tuberculosis.