Comparison between Flow Cytometry and Traditional Culture Methods for Efficacy Assessment of Six Disinfectant Agents against Nosocomial Bacterial Species.

The present study was undertaken to compare the use of flow cytometry (FCM) and traditional culture methods for efficacy assessment of six disinfectants used in Quebec hospitals including: two quaternary ammonium-based, two activated hydrogen peroxide-based, one phenol-based, and one sodium hypochlorite-based. Four nosocomial bacterial species, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Vancomycin-resistant Enterococci faecalis, were exposed to minimum lethal concentrations (MLCs) and sublethal concentrations (1/2 MLCs) of disinfectants under study. The results showed a strong correlation between the two techniques for the presence of dead and live cell populations, as well as, evidence of injured populations with the FCM. The only exception was observed with sodium hypochlorite at higher concentrations where fluorescence was diminished and underestimating dead cell population. The results also showed that FCM can replace traditional microbiological methods to study disinfectant efficacy on bacteria. Furthermore, FCM profiles for E. coli and E. faecalis cells exposed to sublethal concentrations exhibited distinct populations of injured cells, opening a new aspect for future research and investigation to elucidate the role of injured, cultural/noncuturable/resuscitable cell populations in infection control.

Evaluation of bioaerosol exposures during hospital bronchoscopy examinations.

During hospital bronchoscopy examinations, aerosols emitted from the patient's during coughing can be found suspended in the ambient air. The aerosols can contain pathogenic microorganisms. Depending on their size, these microorganisms can remain in the air for a long time. The objective of this study was to measure the sizes and concentrations of the biological and non-biological particles produced during bronchoscopy examinations, and to propose preventive or corrective measures. Two bronchoscopy rooms were studied. An aerodynamic particle sizer (UV-APS) was used to establish the concentrations of the particles present and their size distributions. This instrument determines the aerodynamic diameter of the aerosols and can distinguish fluorescent (bioaerosols) and non-fluorescent particles. Reference concentrations were measured before the start of the examinations (morning background concentrations). They were used as comparison levels for the concentrations measured during and at the end of the bronchoscopies. In parallel, computational fluid dynamics (CFD) made it possible to isolate and understand different factors that can affect the concentration levels in bronchoscopy rooms. The concentrations of the non-fluorescent and fluorescent particles (bioaerosols) were significantly higher (p ≤ 0.05) during the bronchoscopy examinations than the reference concentrations. For the investigated factors, the bioaerosol concentrations were significantly higher during bronchoscope insertion tasks. The time required at the end of the day for the bioaerosols to reach the morning reference concentrations was about fifteen minutes. The average particle sizes were 2.9 µm for the fluorescent particles (bioaerosols) and 0.9 µm for the non-fluorescent particles. Our models based on computational fluid dynamics (CFD) enabled us to observe the behaviour of aerosols for the different rooms.

Lymphopenia as a novel marker of Clostridium difficile infection recurrence.

BACKGROUND: Treatment of Clostridium difficile infection (CDI) is often limited by recurrence in 25% of cases. The objective of this study was to determine risk factors of CDI recurrence during a provincial endemic. METHODS: Data was prospectively collected for 1 year in a Montréal hospital. Inclusion criteria were: age ≥ 18 years; admission for ≥ 72 h; CDI diagnosis during current admission; no CDI diagnosis in the previous 3 months. RESULTS: A total of 121 patients were included, of which 42% were female. Mean age was 77 years, with a median Charlson comorbidity index of 5. Forty patients (33%) had recurrent disease within 2 months of initial CDI treatment. There were 20 deaths (17%) within the 2-month follow-up period. Higher risk of CDI recurrence was independently associated with older age (HR=2.26 for each decade), female gender (HR=1.56), and lymphopenia at completion of CDI treatment (HR=2.18), while a positive C. difficile antitoxin serology was protective (HR=0.17). CDI recurrence was not associated with either lymphopenia at time of diagnosis, underlying comorbidities, severity or treatment of the initial CDI episode, or re-exposure to antibiotics during the follow-up period. CONCLUSION: Lymphopenia at the end of CDI treatment appears to be a strong marker for CDI recurrence. This available and inexpensive test may identify patients who are at higher risk of CDI recurrence.

Risk of Clostridium difficile-associated disease among patients receiving proton-pump inhibitors in a Quebec medical intensive care unit.

Our study was conducted to determine whether use of gastric acid-suppressive agents increased the risk of Clostridium difficile-associated disease (CDAD) in a medical intensive care unit of one of the first hospitals to be threatened by the current CDAD epidemic in Quebec, Canada. Our findings suggest that efforts to determine risk factors for CDAD should focus on other areas, such as older age and antibiotic use.