Enterobacter cloacae Complex Isolates Harboring blaNMC-A or blaIMI-Type Class A Carbapenemase Genes on Novel Chromosomal Integrative Elements and Plasmids.

Carbapenem-resistant Enterobacter cloacae complex isolates submitted to a reference laboratory from 2010 to 2015 were screened by PCR for seven common carbapenemase gene groups, namely, KPC, NDM, OXA-48, VIM, IMP, GES, and NMC-A/IMI. Nineteen of the submitted isolates (1.7%) were found to harbor Ambler class A blaNMC-A or blaIMI-type carbapenemases. All 19 isolates were resistant to at least one carbapenem but susceptible to aminoglycosides, trimethoprim-sulfamethoxazole, tigecycline, and ciprofloxacin. Most isolates (17/19) gave positive results with the Carba-NP test for phenotypic carbapenemase detection. Isolates were genetically diverse by pulsed-field gel electrophoresis macrorestriction analysis, multilocus sequence typing, and hsp60 gene analysis. The genes were found in various Enterobacter cloacae complex species; however, blaNMC-A was highly associated with Enterobacter ludwigii Whole-genome sequencing and bioinformatics analysis revealed that all NMC-A (n = 10), IMI-1 (n = 5), and IMI-9 (n = 2) producers harbored the carbapenemase gene on EludIMEX-1-like integrative mobile elements (EcloIMEXs) located in the identical chromosomal locus. Two novel genes, blaIMI-5 and blaIMI-6, were harbored on different IncFII-type plasmids. Enterobacter cloacae complex isolates harboring blaNMC-A/IMI-type carbapenemases are relatively rare in Canada. Though mostly found integrated into the chromosome, some variants are located on plasmids that may enhance their mobility potential.

Antimicrobial co-resistance patterns of gram-negative bacilli isolated from bloodstream infections: a longitudinal epidemiological study from 2002-2011.

BACKGROUND: Increasing multidrug resistance in gram-negative bacilli (GNB) infections poses a serious threat to public health. Few studies have analyzed co-resistance rates, defined as an antimicrobial susceptibility profile in a subset already resistant to one specific antibiotic. The epidemiologic and clinical utility of determining co-resistance rates are analyzed and discussed. METHODS: A 10-year retrospective study from 2002-2011 of bloodstream infections with GNB were analyzed from three hospitals in Greater Vancouver, BC, Canada. Descriptive statistics were calculated for antimicrobial resistance and co-resistance. Statistical analysis further described temporal trends of antimicrobial resistance, correlations of resistance between combinations of antimicrobials, and temporal trends in co-resistance patterns. RESULTS: The total number of unique blood stream isolates of GNB was 3280. Increasing resistance to individual antimicrobials was observed for E. coli, K. pneumoniae, K. oxytoca, E. cloacae, and P. aeruginosa. Ciprofloxacin resistance in E. coli peaked in 2006 at 40% and subsequently stabilized at 29% in 2011, corresponding to decreasing ciprofloxacin usage after 2007, as assessed by defined daily dose utilization data. High co-resistance rates were observed for ceftriaxone-resistant E. coli with ciprofloxacin (73%), ceftriaxone-resistant K. pneumoniae with trimethoprim-sulfamethoxazole (83%), ciprofloxacin-resistant E. cloacae with ticarcillin-clavulanate (91%), and piperacillin-tazobactam-resistant P. aeruginosa with ceftazidime (83%). CONCLUSIONS: Increasing antimicrobial resistance was demonstrated over the study period, which may partially be associated with antimicrobial consumption. The study of co-resistance rates in multidrug resistant GNB provides insight into the epidemiology of resistance acquisition, and may be used as a clinical tool to aid prescribing empiric antimicrobial therapy.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Canada.

OBJECTIVES: To compare the demographics, antimicrobial susceptibilities and molecular epidemiology of community-associated (CA) and healthcare-associated (HA) methicillin-resistant Staphylococcus aureus (MRSA) in Canada. METHODS: Between 2007 and 2011, 1266 MRSA were collected from inpatients and outpatients attending tertiary-care medical centres across Canada. Susceptibility testing was performed using broth microdilution and isolates were characterized by spa typing and PCR to detect the Panton-Valentine leucocidin (PVL) gene. Detection of heterogeneous vancomycin-intermediate S. aureus (hVISA) was performed using the Etest macromethod and confirmed by population analysis profiling. RESULTS: The annual proportion of S. aureus that were methicillin resistant decreased from 26.1% in 2007 to 19.3% in 2011 (P= 0.0002). Of 1266 MRSA isolated, 366 (28.9%) were CA-MRSA genotypes and 868 (68.6%) were HA-MRSA genotypes. The proportion of MRSA represented by CA-MRSA genotypes increased from 19.7% to 36.4% between 2007 and 2011 (P < 0.0001). CMRSA10 (USA300) was the predominant CA-MRSA genotype (22.1%); the most common HA-MRSA genotype was CMRSA2 (USA100/800) (58.1%). PVL was detected in 328/366 (89.6%) of CA-MRSA genotypes and 6/868 (0.7%) of HA-MRSA genotypes. The hVISA phenotype was detected in 7/27 (25.9%) of MRSA with a vancomycin MIC of 2 mg/L. CONCLUSIONS: The most frequent CA-MRSA genotype was CMRSA10 (USA300), while CMRSA2 (USA100/800) was the predominant HA-MRSA genotype. Despite a decrease in the numbers of MRSA, the proportion of CMRSA10 (USA300) CA-MRSA has risen significantly between 2007 and 2011 in Canada.

Ten-year review of candidemia in a Canadian tertiary care centre: Predominance of non-albicans Candida species.

OBJECTIVE: To review the epidemiology and associated risk factors for candidemia at a tertiary care centre, in view of recent reports on the changing epidemiology of bloodstream infection due to Candida species. METHODS: Between January 2000 and December 2009, patients with blood culture samples positive for Candida species were identified using the microbiology laboratory information system. Patient data were collected by retrospective chart review of clinical characteristics including demographic data, underlying medical diagnoses and risk factors. RESULTS: A total of 266 candidemia episodes were included in the final analysis. Fifty-nine per cent of these episodes occurred in males and 51% were in patients >60 years of age. The most common risk factor for candidemia was previous antibiotic use (85%). The most frequent species was Candida albicans (49%), followed by Candida glabrata (30%). C albicans was the predominant species in all study years with the exception of 2002, in which C glabrata was more frequent. The likelihood of recovering a non-albicans Candida species was found to be significantly associated with previous antifungal therapy (P=0.0004), immunosuppressive therapy (P=0.002), abdominal surgery (P=0.003) and malignancy (P=0.05). Mixed candidemia was found in 10 episodes (4%); 80% grew C albicans and C glabrata. Risk factors for mixed candidemia were not significantly different from those with monomicrobial candidemia. CONCLUSION: C albicans remains the most commonly isolated species in this setting, consistent with findings from other Canadian centres. However, non-albicans Candida species were overall predominant. Mixed-species candidemia does not appear to be more prevalent in patients with identified risk factors.

OBJECTIF: Analyser l'épidémiologie et les facteurs de risque connexes de septicémie à Candida dans un centre de soins tertiaires, compte tenu des récents rapports sur l'évolution de l'épidémiologie des bactériémies causées par des espèces de Candida. MÉTHODOLOGIE: Entre janvier 2000 et décembre 2009, les chercheurs ont déterminé les patients dont l'hémoculture était positive aux espèces de Candida au moyen du système d'information du laboratoire de microbiologie. Ils ont colligé les données à leur sujet au moyen de l'analyse rétrospective des caractéristiques cliniques contenues dans leur dossier, y compris les données démographiques, les diagnostics médicaux sous-jacents et les facteurs de risque. RÉSULTATS: Au total, 266 épisodes de septicémie à Candida ont été inclus dans l'analyse finale. Cinquante-neuf pour cent d'entre eux s'étaient produits chez des hommes, et 51 % chez des patients de plus de 60 ans. La prise antérieure d'antibiotiques était le principal facteur de risque de septicémie à Candida (85 %), et les espèces les plus fréquentes, le Candida albicans (49 %), suivies du Candida glabrata (30 %). Le C albicans était l'espèce prédominante dans toutes les années d'étude, sauf en 2002, où il était détrôné par le C glabrata. La possibilité de dépister une autre espèce que le C albicans s'associait nettement à une thérapie anti-fongique antérieure (P=0,0004), à une thérapie immunosuppressive (P=0,002), à une chirurgie abdominale (P=0,003) et à une tumeur maligne (P=0,05). Dans dix épisodes (4 %), les chercheurs ont observé une septicémie à Candida mixte, dont 80 % d'association de C albicans et de C glabrata. Les facteurs de risque de septicémie à Candida mixte ne différaient pas de manière significative de ceux des septicémies à Candida monomicrobiennes. CONCLUSION: Le C albicans demeure l'espèce la plus isolée dans ce contexte, ce qui correspond aux observations d'autres centres canadiens. Cependant, dans l'ensemble, les autres espèces que le C albicans étaient prédominantes. Les septicémies à Candida mixtes ne semblent pas plus prévalentes chez les patients ayant des facteurs de risque déterminés.

Potential influence of rapid diagnostics on timeliness of management decisions for patients with positive blood cultures.

Background: The Accelerate Pheno system (AXDX) provides rapid identification (ID; 90 minutes) and antimicrobial susceptibility testing (AST; approximately 7 hours) from positive blood culture (BC) bottles. We assessed the potential of AXDX results to influence more timely antibiotic interventions with a convenience sample of 158 positive BCs. Methods: BCs with a mono-microbial Gram stain likely to be on the AXDX panel were run in parallel with the standard of care (SOC). Using results from the SOC, the medical microbiologist on call (MMOC) noted interventions made at the time of BC Gram stain and when ID and AST results were available. The timing of MMOC intervention was noted and compared with fastest potential SOC time and AXDX time. Results: Of 158 specimens selected for analysis, 144 were evaluable. ID was available 11.9 hours and AST 27.7 hours faster than SOC. Correct ID was provided for 85.2% of specimens and AST for 59.0% of specimens, with 97.5% essential agreement compared with the SOC. One hundred and thirteen clinical interventions were made on 100 specimens: 54.9% were narrowing; 33.6%, escalation; 6.2%, consultation with ID; and 3.5%, further investigation. If AXDX data had been used immediately once available, interventions would have been possible 24 hours earlier for ID interventions and 39 hours earlier for AST results. Conclusions: Results from rapid diagnostic panels such as AXDX have the potential to support timely antimicrobial de-escalation and other decisions to benefit patients, especially if paired with stewardship interventions.

Historique: Le système Accelerate Pheno (AXDX) permet de procéder à une identification rapide (ID; 90 minutes) et à des tests de susceptibilité antimicrobienne (AST; environ sept heures) à partir de bouteilles d'hémoculture (BH) positives. À l'aide d'un échantillon de commodité de 158 BH positives, les auteurs ont évalué le potentiel de résultats du système AXDX pour favoriser des interventions antibiotiques plus opportunes. Méthodologie: Les auteurs ont comparé les BH présentant une coloration de Gram monomicrobienne susceptible de se trouver sur le panel AXDX avec la norme de soins (NdS). À l'aide des résultats de la NdS, le microbiologiste médical sur appel (MMSA) a consigné les interventions effectuées au moment de la coloration de Gram de la BH et lorsque les résultats de l'ID et de l'AST étaient disponibles. Le moment de l'intervention du MMSA était consigné et comparé avec la durée de la NdS au potentiel le plus rapide et la durée de l'AXDX. Résultats: Des 158 échantillons sélectionnés en vue d'être analysés, 144 étaient évaluables. L'ID était disponible 11,9 heures et l'AST, 27,7 heures plus rapidement que la NdS. L'ID exacte était fournie pour 85,2 % des échantillons et l'AST exacte, pour 59,0 % des échantillons, selon une entente essentielle de 97,5 % par rapport à la NdS. Cent treize interventions ont été effectuées sur 100 échantillons : 54,9 % visaient à réduire le spectre, 33,6 %, à accroître la médication, 6,2 %, à demander une consultation avec l'ID et 3,5 %, à obtenir des explorations plus approfondies. Si les données de l'AXDX avaient été utilisées dès l'obtention des résultats, il aurait été possible d'agir 24 heures plus rapidement pour les interventions d'ID et 39 heures plus rapidement pour les résultats de l'AST. Conclusions: Les résultats des panels diagnostiques rapides comme l'AXDX ont le potentiel de favoriser une désescalade antimicrobienne et d'autres décisions au profit des patients, surtout s'ils s'associent à des interventions de gestion.

Microbiologic investigations for head and neck infections.

A variety of methods, including direct examination of stained smears, antigen detection, routine and special cultures, and histopathologic evaluation are available for investigation of head and neck infections. Newer rapid molecular techniques with increased sensitivity and specificity are becoming available at many centers. Evaluation of specific causes in head and neck infections is complicated by the tendency for polymicrobial infections, difficulty in obtaining adequate specimens, and the presence of a diverse endogenous microflora at various mucosal sites that also can include true pathogens. These aspects of laboratory investigation for head and neck infections are reviewed in this article.

The antimicrobial effect of nitric oxide on the bacteria that cause nosocomial pneumonia in mechanically ventilated patients in the intensive care unit.

BACKGROUND: Nosocomial pneumonia is the second most frequent nosocomial infection and the leading cause of death from hospital-acquired infection. Endogenously produced nitric oxide is an important component of the body's natural defense mechanism. Recent studies have demonstrated that exogenous gaseous nitric oxide (gNO) is bactericidal and that inhaled gNO is beneficial to bacterial clearance. OBJECTIVE: Determine the antimicrobial effect of exogenous gNO in vitro against organisms from culture collections and pathogens derived from tracheal aspirates of mechanically ventilated patients with pneumonia in an intensive care unit. METHODS: Using bacterial isolates in pure culture, a 0.5 McFarland standard (10(8) colony-forming-units [cfu] per mL) was prepared and further diluted to 1:1,000 with saline, to 10(5) cfu/mL. For each isolate tested, 3 mL was pipetted into each well of a 6-well plate, and placed in a specially designed incubator with compartments for both a treatment arm and a control arm. Both chambers received a continuous flow of heated, humidified gas. The treatment chamber had 200 ppm of gNO in the gas flow, which is higher than the clinically accepted concentration for gNO. Samples were drawn off at time intervals, plated onto Columbia agar base with 5% sheep blood, and placed in a traditional incubator at 35 degrees C for a minimum of 24 h. All tests were performed in duplicate. The colony-forming units were visually counted to determine percentage kill. RESULTS: There was total kill (100% of all colony-forming units) of each bacterial strain subjected to the test conditions at between 2 and 6 h of exposure to 200 ppm gNO. CONCLUSION: gNO is bactericidal against various strains of bacteria suspended in saline, including both Gram-positive and Gram-negative organisms, and those that commonly cause nosocomial pneumonia in mechanically ventilated patients. Future work should focus on developing strategies that maximize the antimicrobial effect while minimizing the effect of these same interventions on host cells.

Cryptococcus neoformans infections at Vancouver Hospital and Health Sciences Centre (1997-2002): epidemiology, microbiology and histopathology.

An outbreak of infections due to a rare subspecies of Cryptococcus neoformans (var. gattii) was recognized on Vancouver Island (VI), British Columbia, in 2002, which had affected 59, mostly immunocompetent, individuals since 1999. The objectives of this study were to: (1) determine if the outbreak had spread to Vancouver and its surrounding communities and (2) review the epidemiological, clinical and pathological features of all cryptococcal infections in patients admitted to the Vancouver Hospital and Health Sciences Centre (VHHSC) over a 5 year period. VHHSC microbiology and pathology databases were searched for cryptococcal infections from 1 June 1997 to 31 December 2002. Hospital charts of all identified patients were reviewed. Available cryptococcal isolates and histopathological specimens were reviewed. Twenty-six cases of cryptococcosis were identified in both HIV-positive (n = 15) and HIV-negative (n = 11) patients. C. neoformans var. grubii was cultured from 13 patients, of whom 10 were HIV-positive. The outbreak strain, C. neoformans var. gattii, was detected in three patients; all had travelled to VI. C. neoformans var. neoformans was cultured from two patients, Cryptococcus laurentii was cultured from one, and seven patients had cryptococcosis based on histopathology alone, without cultures. The majority (10/15) of the HIV-positive patients developed systemic disease whilst HIV-negative patients (8/11) presented with pulmonary cryptococcosis. Lung biopsies revealed necrotizing and/or fibrosing granulomas, with cryptococcal cells in 5 of 10 specimens. Brain biopsies showed cryptococcal organisms within leptomeninges and deeper structures with minimal associated inflammation. This retrospective study demonstrated a sharp increase in the total number of C. neoformans infections in both immunocompromised and immunocompetent patients at the VHHSC in 2002. There was no evidence of spread of the outbreak strain to the Greater Vancouver area. This is the first correlation of clinical and investigational findings of cryptococcosis in a region in North America where C. neoformans varieties gattii and grubii are endemic.

Antibiotic resistance in isolates recovered from women with community-acquired urinary tract infections presenting to a tertiary care emergency department.

INTRODUCTION: We sought to determine the antibiotic susceptibility of organisms causing community-acquired urinary tract infections (UTIs) in adult females attending an urban emergency department (ED) and to identify risk factors for antibiotic resistance. METHODS: We reviewed the ED charts of all nonpregnant, nonlactating adult females with positive urine cultures for 2008 and recorded demographics, diagnosis, complicating factors, organism susceptibility, and risk factors for antibiotic resistance. Odds ratios (ORs) and 95% confidence intervals (CIs) for potential risk factors were calculated. RESULTS: Our final sample comprised 327 UTIs: 218 were cystitis, of which 22 were complicated cases and 109 were pyelonephritis, including 22 complicated cases. Escherichia coli accounted for 82.3% of all UTIs, whereas Staphylococcus saprophyticus accounted for 5.2%. In uncomplicated cystitis, 9.5% of all isolates were resistant to ciprofloxacin and 24.0% to trimethoprim-sulfamethoxazole (TMP-SMX). In uncomplicated pyelonephritis, 19.5% of isolates were resistant to ciprofloxacin and 36.8% to TMP-SMX. In UTI (all types combined), any antibiotic use within the previous 3 months was a significant risk factor for resistance to both ciprofloxacin (OR 3.34, 95% CI 1.16-9.62) and TMP-SMX (OR 4.02, 95% CI 1.48-10.92). Being 65 years of age or older and having had a history of UTI in the previous year were risk factors only for ciprofloxacin resistance. CONCLUSIONS: E. coli was the predominant urinary pathogen in this series. Resistance to ciprofloxacin and TMP-SMX was high, highlighting the importance of relevant, local antibiograms. Any recent antibiotic use was a risk factor for both ciprofloxacin and TMP-SMX resistance in UTI. Our findings should be confirmed with a larger prospective study.

Coordinated response to SARS, Vancouver, Canada.

Two Canadian urban areas received travelers with severe acute respiratory syndrome (SARS) before the World Health Organization issued its alert. By July 2003, Vancouver had identified 5 cases (4 imported); Toronto reported 247 cases (3 imported) and 43 deaths. Baseline preparedness for pandemic threats may account for the absence of sustained transmission and fewer cases of SARS in Vancouver.