Browsing by Author "Church, Deirdre"

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    Community-Associated Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia without Evidence of Antecedent Viral Upper Respiratory Infection
    (2014-01-01) Toro, Cristina Moran; Janvier, Jack; Zhang, Kunyan; Fonseca, Kevin; Gregson, Dan; Church, Deirdre; Laupland, Kevin; Rabin, Harvey; Elsayed, Sameer; Conly, John
    BACKGROUND: USA300 community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) strains causing necrotizing pneumonia have been reported in association with antecedent viral upper respiratory tract infections (URI).METHODS: A case series of necrotizing pneumonia presenting as a primary or coprimary infection, secondary to CA-MRSA without evidence of antecedent viral URI, is presented. Cases were identified through the infectious diseases consultation service records. Clinical and radiographic data were collected by chart review and electronic records. MRSA strains were isolated from sputum, bronchoalveolar lavage, pleural fluid or blood cultures and confirmed using standard laboratory procedures. MRSA strains were characterized by susceptibility testing, pulsed-field gel electrophoresis, spa typing, agr typing and multilocus sequence typing. Testing for respiratory viruses was performed by appropriate serological testing of banked sera, or nucleic acid testing of nasopharyngeal or bronchoalveloar lavage specimens.RESULTS: Ten patients who presented or copresented with CA necrotizing pneumonia secondary to CA-MRSA from April 2004 to October 2011 were identified. The median length of stay was 22.5 days. Mortality was 20.0%. Classical risk factors for CA-MRSA were identified in seven of 10 (70.0%) cases. Chest tube placement occurred in seven of 10 patients with empyema. None of the patients had historical evidence of antecedent URI. In eight of 10 patients, serological or nucleic acid testing testing revealed no evidence of acute viral coinfection. Eight strains were CMRSA-10 (USA300). The remaining two strains were a USA300 genetically related strain and a USA1100 strain.CONCLUSION: Pneumonia secondary to CA-MRSA can occur in the absence of an antecedent URI. Infections due to CA-MRSA are associated with significant morbidity and mortality. Clinicians need to have an awareness of this clinical entity, particularly in patients who are in risk groups that predispose to exposure to this bacterium.
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    Differential Yield of Pathogens from Stool Testing of Nosocomial versus Community-Acquired Paediatric Diarrhea
    (1999-01-01) Deorari, Savita; McConnell, Athena; Tan, Kah-Kee; Jadavji, Nadeem; Ma, Doreen; Church, Deirdre; Katzko, Gary; Gall, D Grant; Jadavji, Taj; Davies, H Dele
    OBJECTIVES: To evaluate the role of routine stool examination for all pathogens in paediatric nosocomial diarrhea (NAD) and community-acquired diarrhea (CAD) over a two-year period at Alberta Children’s Hospital and current practices in other Canadian hospitals. A secondary objective was to characterize features that may predict NAD or CAD etiology.STUDY DESIGN: Retrospective cohort study and telephone survey.SETTING: Alberta Children’s Hospital (retrospective review) and Canadian tertiary care paediatric centres (telephone survey).METHODS: The health and microbiological records of all children with an admission or discharge diagnosis of diarrhea were reviewed using a standardized data collection form. In addition, a telephone survey of laboratories serving all paediatric hospitals in Canada was conducted using a standard questionnaire to obtain information about practices for screening for pathogens related to NAD.RESULTS: Four hundred and thirty-four CAD episodes and 89 NAD episodes were identified. Overall, rotavirus and Clostridium difficile were the most commonly identified pathogens. Bacterial culture was positive in 10.6% CAD episodes tested, with Escherichia coli O157:H7 identified as the most common non-C difficile organism. In NAD, no bacteria were identified other than C difficile (toxin). Screening for ova and parasites had negligible yield. Viruses were more frequent in the winter months, while bacterial pathogens were more common in the summer and fall months. Over 50% of Canadian paediatric hospitals still routinely process NAD specimens similarly to CAD specimens.CONCLUSIONS: There is a need for the re-evaluation of routine ova and parasite screening, and bacterial culture in nonoutbreak episodes of NAD in children.
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    Endocarditis caused by an oral taxon species of Bergeyella identified by partial 16S rDNA sequencing: case report and review of the literature
    (University of Toronto Press, 2017) Clark, Lauren; Parkins, Michael D; Chow, Barbara L; Lynch, Tarah; Church, Deirdre
    Bergeyella spp bacteremia is a rare cause of infective endocarditis and is typically associated with animal contact. This case report presents a case of culture-negative endocarditis caused by Bergeyella spp oral taxon 422 in a 49-year-old man with severe periodontal disease but no animal contact. Multiple sets of blood cultures were negative, but broad-range 16S rDNA polymerase chain reaction (PCR) amplification and sequencing repeatedly detected this organism in the patient’s bloodstream. Empiric broad-spectrum antibiotic treatment against Bergeyella spp resulted in resolution of clinical symptoms, resolution of bloodstream infection, and cure. This is the first human case of endocarditis caused by an oral-associated species of Bergeyella described in the literature. Culture-negative endocarditis due to Bergeyella spp from severe periodontal disease may be missed unless molecular detection methods are used.
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    Evaluation of Potential Factors Contributing to Microbiological Treatment Failure in Streptococcus Pyogenes Pharyngitis
    (2001-01-01) Kuhn, Susan M; Preiksaitis, Jutta; Tyrrell, Gregory J; Jadavji, Taj; Church, Deirdre; Davies, H Dele
    BACKGROUND: A cohort study of children with pharyngitis aged two to 16 years was conducted to assess the role of microbial and host factors in group A beta-hemolytic streptococcus (GABHS) microbiological treatment failure. METHODS: GABHS-infected children had pharyngeal swabs repeated two to five days after completing a 10-day course of penicillin V. M and T typing, and pulsed field gel electrophoresis were performed on the isolates, and the isolates were evaluated for tolerance. Patient characteristics and clinical features were noted and nasopharyngeal swabs for respiratory viruses were taken at enrolment. RESULTS AND CONCLUSIONS: Of 286 patients enrolled, 248 (87%) could be evaluated. GABHS was cultured from 104 patients (41.9%), of whom 33 (33.7%) had microbiological treatment failures on follow-up. Although there was a trend toward failure for younger children (mean 6.5±2.4 years versus 7.3±2.4 years, P=0.07) and M type 12 (24% versus 10%, P=0.08), no factors were associated with treatment failure.
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    Incidence, susceptibility and outcomes of candidemia in adults living in Calgary, Alberta, Canada (2010–2018)
    (2023-02-20) Bourassa-Blanchette, Samuel; Biesheuvel, Marit M.; Lam, John C.; Kipp, Alexander; Church, Deirdre; Carson, Julie; Dalton, Bruce; Parkins, Michael D.; Barkema, Herman W.; Gregson, Daniel B.
    Abstract Background Candidemia is increasing in frequency and is associated with high mortality. We sought to determine the burden of illness, the population it affects and its resistance profile in our region. Methods The Calgary Zone (CZ) provides all care for residents of Calgary and surrounding communities (~ 1.69 million) via five tertiary hospitals each served by a common single laboratory for acute care microbiology. All adult patients in the CZ with at least one Candida spp.-positive blood culture between January 1, 2010, and December 31, 2018, were identified using microbiological data from Calgary Lab Services, the laboratory that processes > 95% of all blood culture samples in the CZ, were reviewed for the study. Results The overall annual incidence of candidemia among individuals living in the CZ was 3.8 per 100,000 persons (Median age 61 years (IQR 48–72) and 221/455 (47.4%) were female). C. albicans was the most common species (50.6%), followed by C. glabrata, (24.0%). No other species accounted for more than 7% of cases. Overall mortality at 30, 90, and 365 days was 32.2, 40.1, and 48.1% respectively. Mortality rate did not differ by Candida species. Of individuals who developed candidemia, more than 50% died within the next year. No new resistance pattern has emerged in the most common Candida species in Calgary, Alberta. Conclusions In Calgary, Alberta, the incidence of candidemia has not increased in the last decade. C. albicans was the most common species and it remains susceptible to fluconazole.
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    Not All Pseudomembranous Colitis is Caused by Clostridium difficile
    (2008-01-01) Janvier, Jack; Kuhn, Susan; Church, Deirdre
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    Plasmid mediated AmpC B-lactamases in E. coli clinical isolated in Calgary Health Region (CHR)
    (2005) Nasim, Khalida; Gregson, Daniel B.; Church, Deirdre
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    Point Prevalence Study of Antibiotic Susceptibility of Genital Group B Streptococcus Isolated from Near-Term Pregnant Women in Calgary, Alberta
    (2012-01-01) Church, Deirdre; Carson, Julie; Gregson, Dan
    BACKGROUND: Genital group B streptococcus (GBS) may be transmitted from a colonized mother to her infant if appropriate intrapartum antibiotic prophylaxis is not given. A recent case of GBS neonatal sepsis occurred due to an erythromycin-intermediate strain after empirical use of this drug as intrapartum prophylaxis.OBJECTIVE: To determine the regional antibiotic resistance rates of genital GBS isolates to penicillin, erythromycin and clindamycin.METHODS: A total of 309 genital GBS strains cultured from vaginal/rectal swabs were prospectively isolated and randomly selected between March and May 2011. Etest strips (bioMèrieux, France) were used to determine the minimum inhibitory concentrations to penicillin, erythromycin and clindamycin according to standard methods. All isolates that either demonstrated intermediate or full resistance to erythromycin had a D-test performed to detect inducible resistance to clindamycin. The resistance mechanism for each isolate was inferred from its antibiogram phenotype.RESULTS: All genital GBS isolates were susceptible to penicillin, but high rates of resistance were found to both erythromycin (25%) and clindamycin (22%), mainly due to acquisition of erythromycin ribosomal methylation genes (erm) that result in the MLSB resistance phenotype. Most often the MLSB resistance phenotype was constitutive (MLSB-C; 14.2%) rather than inducible (MLSB-I; 8.1%), and an efflux mechanism (msrA; 3%) was much less common.DISCUSSION: The present article is the first point prevalence study of genital GBS antibiogram profile that has been reported from a Canadian health care region. The high rates of resistance of genital GBS to both erythromycin and clindamycin is mainly due to the acquisition and spread of erm genes conveying the MSLB phenotype.CONCLUSION: Changes to clinical and laboratory practice in the Calgary, Alberta, region were made to prevent additional cases of neonatal GBS sepsis due to inappropriate intrapartum antibiotic prescription.
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    Population-Based Laboratory Surveillance of Imported Malaria in Metropolitan Calgary, 2000–2011
    (PLoS ONE, 2013-04-15) Lee, Clara S.; Gregson, Daniel B.; Church, Deirdre; Laupland, Kevin B.; Eckhardt, Rose; Ross, Terry; Chan, Wilson; Pillai, Dylan R.
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    Pyogenic Ventriculitis Complicating Aggregatibacter aphrophilus Infective Endocarditis: A Case Report and Literature Review
    (2009-01-01) Jung, Gordon W; Parkins, Michael D; Church, Deirdre
    Pyogenic ventriculitis (PV) is an uncommon, but frequently fatal infection that results from inflammation of the ventricular ependymal lining associated with a purulent ventricular system. PV has been rarely reported as a secondary complication of infective endocarditis. Prompt diagnosis and treatment with appropriate culture-directed antibiotics with adequate central nervous system penetration is crucial when managing patients who are suspected of having PV. The present study reports on a fatal case of a previously well 42-year-old alcoholic woman with infective endocarditis caused by Aggregatibacter aphrophilus, with secondary brain abscess and spontaneous rupture into the ventricles causing PV.
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    Severe facial necrosis in a type 1 diabetic patient secondary to mucormycosis masquerading as an internal maxillary artery occlusion: a case report
    (2019-02-22) Manji, Farheen; Lam, John C; Meatherall, Bonnie L; Church, Deirdre; Missaghi, Bayan
    Abstract Background Mucormycosis is a group of rare but life threatening angioinvasive infections caused by fungi of the order Mucorales that often occurs in immunocompromised patients and individuals with poorly controlled diabetes. Rhinocerebral mucormycosis can mimic sinusitis but can rapidly progress to deeper disease and cause facial necrosis. Facial vascular thrombosis is a rare complication of mucormycosis and can confound diagnosis of the disease. Case presentation We report the case of a 25-year-old female with poorly controlled type 1 diabetes mellitus who initially presented with symptoms of sinusitis but rapidly progressed with signs of left-sided facial necrosis due to occlusion of the left internal maxillary artery. Early surgical debridement did not yield a microbiological diagnosis. Deeper surgical debridements ultimately revealed angioinvasive fungal disease consistent with mucormycosis. The patient recovered after repeated surgical intervention and aggressive parenteral antifungal therapy. Conclusion This case illustrates an atypical complication of mucormycosis, and emphasizes that a high index of suspicion in vulnerable patient populations aids in the diagnosis of this life-threatening infection.
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    Studying Infection Transmission Dynamics Amongst Individuals with Cystic Fibrosis
    (2023-11-27) Izydorczyk, Conrad; Parkins, Michael; Church, Deirdre; Pillai, Dylan; Wasmuth, James; Surette, Michael
    Cystic fibrosis (CF) impairs the natural immune defenses of the lungs and leaves affected individuals susceptible to incident and chronic lung infections by a variety of microbial pathogens. The potential for patient-to-patient transmission of lung infections between persons with CF (pwCF) was first realized in the 1980's with incident infections caused by members of the Burkholderia cepacia complex, followed in the 1990’s by the recognition of epidemic strains of the archetypal CF pathogen, Pseudomonas aeruginosa. To mitigate this risk, progressively stringent infection prevention and control (IPC) guidelines have been implemented to prevent further spread amongst pwCF. However, few longitudinal studies assessing the potential for transmission of CF pathogens have been performed. Accordingly, the primary objective of this thesis was to investigate the natural history and potential for transmission of four key CF pathogens amongst pwCF attending the Southern Alberta Adult CF Clinic (SAACFC) in Calgary, Canada between 2002-2020: Escherichia coli, Haemophilus influenzae, Stenotrophomonas maltophilia, and P. aeruginosa. Whole-genome sequencing +/- pulse field gel electrophoresis were utilized for investigating infection transmission to achieve maximal resolution. A wide variety of genomic approaches were investigated for the inference of patient-to-patient transmission from genomic data, including several measures of genetic relatedness, phylogenetics, and pangenome analyses. These were combined with investigations of epidemiological linkages between pwCF to identify potential transmission opportunities. While a high degree of strain sharing was observed for all examined species, healthcare associated patient-to-patient transmission was rare through two decades. No instances of potential transmission were observed between 2002-2020 for E. coli, H. influenzae, or S. maltophilia, while infrequent transmission was postulated for P. aeruginosa. However, evidence of widespread historical transmission of epidemic P. aeruginosa strains was observed prior to patients entering the SAACFC. These findings corroborate the paradigm that most lung infections in pwCF in the current era of rigorous IPC mandates are acquired by independent acquisition events from independent environmental sources. Overall, the findings of this thesis contribute not only to CF and infection control literature, but also to the application of whole-genome sequencing to the study of infection transmission.