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Background. An increase in the incidence and severity of Clostridium difficile-associated disease in Québec and the United States has been associated with a hypervirulent strain referred to as North American pulsed-field type 1 (NAP1)/027. Methods. In 2005, a prospective study was conducted in 88 Québec hospitals, and 478 consecutive nosocomial isolates of C. difficile were obtained. The isolates were subjected to pulsed-field gel electrophoresis (PFGE) typing, antimicrobial susceptibility testing, and detection of binary toxin genes and tcdC gene deletion. Data on patient age and occurrence of complications were collected. Results. PFGE typing of 478 isolates of C. difficile yielded 61 PFGE profiles. Pulsovars A (57%), B (10%), and B1 (8%) were predominant. The PFGE profile of pulsovar A was identical to that of strain NAP1. It showed 67% relatedness with 15 other PFGE patterns, among which 11 had both binary toxin genes and a partial tcdC deletion but different antibiotic susceptibility profiles. Pulsovars B and B1 were identical to strain NAP2/ribotype 001. In hospitals showing a predominant clonal A or B-B1 PFGE pattern, incidence of C. difficile-associated disease was 2 and 1.3 times higher, respectively, than in hospitals without any predominant clonal PFGE pattern. Severe disease was twice as frequent among patients with strains possessing binary toxin genes and tcdC deletion than among patients with strains lacking these virulence factors. Conclusions. This study helped to quantify the impact of strain NAP1 on the incidence and severity of C. difficile-associated disease in Québec in 2005. The identification of the geographic dissemination of this predominant strain may help to focus regional infection-control efforts.

In the first half of 2003, the number of C. difficile infections (22.5 per 1000 admissions) increased in Quebec, Canada. This outbreak was associated with fluoroquinolone and cephalosporin use as well as an increase in C. difficile –associated mortality (to 6.9 percent) and colectomy (to 1.9 percent). The outbreak strain was found to have enhanced virulence, as suggested by the presence of binary toxin genes and the partial deletion of a toxin-repressor gene. In the first half of 2003, the number of C. difficile infections (22.5 per 1000 admissions) increased in Quebec, Canada. This outbreak was associated with fluoroquinolone and cephalosporin use as well as an increase in C. difficile –associated mortality and colectomy. Clostridium difficile is the leading cause of nosocomial infectious diarrhea. 1 The most important risk factor for C. difficile –associated diarrhea is prior antibiotic use. 2 Some patients remain asymptomatic after exposure to C. difficile, whereas illness ranging from mild diarrhea to fulminant colitis develops in others. 2 Only 1 to 5 percent of affected patients have severe disease, leading to colectomy, intensive care, or death. 3 , 4 The best-described C. difficile virulence factors are toxins A and B, encoded by the genes tcdA and tcdB, respectively. 5 Together with two regulatory genes ( tcdC and tcdD ) and a porin gene ( tcdE ), . . .

The ability and willingness of health care workers to report for work during a pandemic are essential to pandemic response. The main contribution of this article is to examine the relationship between risk perception of personal and work activities and willingness to report for work during an influenza pandemic. Data were collected through a quantitative Web-based survey sent to health care workers on the island of Montreal. Respondents were asked about their perception of various risks to obtain index measures of risk perception. A multinomial logit model was applied for the probability estimations, and a factor analysis was conducted to compute risk perception indexes (scores). Risk perception associated with personal and work activities is a significant predictor of intended presence at work during an influenza pandemic. This means that correcting perceptual biases should be a public policy concern. These results have not been previously reported in the literature. Many organizational variables are also significant.

In this prospective cohort study of patients admitted to hospitals in Quebec and Ontario, 2.8% of patients had Clostridium difficile infection and 3.0% had asymptomatic C. difficile colonization during hospitalization. Most patients with C. difficile infection had the NAP1 strain. Clostridium difficile is the leading cause of health care–associated infectious diarrhea. 1 After exposure to C. difficile, some patients remain asymptomatic, whereas others have illness ranging from mild diarrhea to fulminant colitis. 2 Outbreaks of C. difficile infection in North America and Europe have been attributed to the emergence of an epidemic strain (North American pulsed-field gel electrophoresis [PFGE] type 1 [NAP1]). 3 , 4 Risk factors for C. difficile infection include antibiotic use, advanced age, increased severity of underlying illness, prior hospitalization, use of feeding tubes, gastrointestinal surgery, and use of proton-pump inhibitors. 5 , 6 Variability in host factors may explain the wide spectrum . . .

Previous observations have indicated that infection with Clostridium difficile occurs almost exclusively after exposure to antibiotics, but more recent observations have suggested that prior antibiotic exposure may be less frequent among cases of community-acquired disease. We used 2 linked health databases to perform a matched, nested case—control study of elderly patients admitted to hospital with community-acquired C. difficile infection. For each of 836 cases among people 65 years of age or older, we selected 10 controls. We determined the proportion of cases that occurred without prior antibiotic exposure and estimated the risk related to exposure to different antibiotics and the duration of increased risk. Of the 836 cases, 442 (52.9%) had no exposure to antibiotics in the 45-day period before the index date, and 382 (45.7%) had no exposure in the 90-day period before the index date. Antibiotic exposure was associated with a rate ratio (RR) of 10.6 (95% confidence interval [CI] 8.9–12.8). Clindamycin (RR 31.8, 95% CI 17.6–57.6), cephalosporins (RR 14.9, 95% CI 10.9–20.3) and gatifloxacin (RR 16.7, 95% CI 8.3–33.6) were associated with the highest risk. The RR for C. difficile infection associated with antibiotic exposure declined from 15.4 (95% CI 12.2–19.3) by about 20 days after exposure to 3.2 (95% CI 2.0–5.0) after 45 days. Use of a proton pump inhibitor was associated with increased risk (RR 1.6, 95% CI 1.3–2.0), as were concurrent diagnoses of inflammatory bowel disease (RR 4.1, 95% CI 2.6–6.6), irritable bowel syndrome (RR 3.4, 95% CI 2.3–5.0) and renal failure (RR 1.7, 95% CI 1.2–2.2). Community-acquired C. difficile infection occurred in a substantial proportion of individuals with no recent exposure to antibiotics. Among patients who had been exposed to antibiotics, the risk declined markedly by 45 days after discontinuation of use.

The confident discrimination of nucleic acids that share a high degree of sequence identity is the major obstacle for the widespread applicability of multiplex DNA-based techniques. This diagnostic uncertainty originates in the insufficient specificity of hybridization, allowing cross-hybridization between unwanted probe–target combinations. Starting from a random mixture of oligonucleotides, we describe a protocol to selectively amplify the probes that bind to the target but not to the similar, unintended targets. The procedure involves five forward hybridizations to generate pools of probes with significant affinity, but not necessarily specificity, for the target. Specificity is then achieved during subtractive hybridization steps, where only probes having differential diagnostic performance are retained. Iterative hybridizations, cloning, sequencing and testing of the performance of selected probes can all be fully automated. Eight weeks are required for the full completion of a project composed of 40 probe–target pairs, even when targets share as much as 87% of sequence identity. While alternative, computer-assisted, rational oligonucleotide design may produce an uncertain outcome, the present protocol generates robust and specific probes suitable for a variety of multiplex, nucleic acid-based detection/typing platforms.

Clostridium difficile is an anaerobic, Gram-positive bacterium that has been implicated as the leading cause of antibiotic-associated diarrhea. Metronidazole is currently the first-line treatment for mild to moderate C. difficile infections. Our laboratory isolated a strain of C. difficile with a stable resistance phenotype to metronidazole. A shotgun proteomics approach was used to compare differences in the proteomes of metronidazole-resistant and -susceptible isolates. NAP1 C. difficile strains CD26A54_R (Met-resistant), CD26A54_S (reduced- susceptibility), and VLOO13 (Met-susceptible) were grown to mid-log phase, and spiked with metronidazole at concentrations 2 doubling dilutions below the MIC. Peptides from each sample were labeled with iTRAQ and subjected to 2D-LC-MS/MS analysis. In the absence of metronidazole, higher expression was observed of some proteins in C. difficile strains CD26A54_S and CD26A54_R that may be involved with reduced susceptibility or resistance to metronidazole, including DNA repair proteins, putative nitroreductases, and the ferric uptake regulator (Fur). After treatment with metronidazole, moderate increases were seen in the expression of stress-related proteins in all strains. A moderate increase was also observed in the expression of the DNA repair protein RecA in CD26A54_R. This study provided an in-depth proteomic analysis of a stable, metronidazole-resistant C. difficile isolate. The results suggested that a multi-factorial response may be associated with high level metronidazole-resistance in C. difficile, including the possible roles of altered iron metabolism and/or DNA repair.

Abstract During 4 Clostridium difficile infection outbreaks, unit-wide screening of 114 patients led to detection and isolation of 15 (13%) C. difficile asymptomatic carriers. Carriage prevalence varied between outbreaks, from 0% to 29% (P = .004). Isolating carriers was not associated with significantly shorter outbreak durations, compared with historical controls.

Background Healthcare acquired infections (HAI) are an important public health problem in developed countries, but comprehensive data on trends over time are lacking. Prevalence surveys have been used as a surrogate for incidence studies and can be readily repeated. Methods The Canadian Nosocomial Infection Surveillance Program conducted prevalence surveys in 2002 and 2009 in a large network of major Canadian acute care hospitals. NHSN definitions of HAI were used. Use of isolation precautions on the survey day was documented. Results In 2009, 9,953 acute care inpatients were surveyed; 1,234 infections (124/1000) were found, compared to 111/1000 in 2002, ( p  < 0.0001). There was increased prevalence of urinary tract infection (UTI) and Clostridium difficile , offset by decreases in pneumonia and bloodstream infection. Use of isolation precautions increased from 77 to 148 per 1000 patients ( p  < 0.0001), attributable to increased use of contact precautions in patients infected or colonized with antimicrobial resistant organisms. Conclusion Between 2002 and 2009 HAI prevalence increased by 11.7 % in a network of major Canadian hospitals due to increases in Clostridium difficile and urinary tract infection. The use of isolation precautions increased by 92.2 % attributable to increased contact isolation. National prevalence surveys are useful tools to assess evolving trends in HAI.