Ousmane Traore

Modification of the surfaces of medical devices to prevent microbial adhesion and biofilm formation.

BACKGROUND The development of devices with surfaces that have an effect against microbial adhesion or viability is a promising approach to the prevention of device-related infections. AIM To review the strategies used to design devices with surfaces able to limit microbial adhesion and/or growth. METHODS A PubMed search of the published literature. FINDINGS One strategy is to design medical devices with a biocidal agent. Biocides can be incorporated into the materials or coated or covalently bonded, resulting either in release of the biocide or in contact killing without release of the biocide. The use of biocides in medical devices is debated because of the risk of bacterial resistance and potential toxicity. Another strategy is to modify the chemical or physical surface properties of the materials to prevent microbial adhesion, a complex phenomenon that also depends directly on microbial biological structure and the environment. Anti-adhesive chemical surface modifications mostly target the hydrophobicity features of the materials. Topographical modifications are focused on roughness and nanostructures, whose size and spatial organization are controlled. The most effective physical parameters to reduce bacterial adhesion remain to be determined and could depend on shape and other bacterial characteristics. CONCLUSIONS A prevention strategy based on reducing microbial attachment rather than on releasing a biocide is promising. Evidence of the clinical efficacy of these surface-modified devices is lacking. Additional studies are needed to determine which physical features have the greatest potential for reducing adhesion and to assess the usefulness of antimicrobial coatings other than antibiotics.

Eradication of microorganisms embedded in biofilm by an ethanol-based catheter lock solution

BACKGROUND Interdialytic locking of catheters with antimicrobial agents is frequently used for preventing catheter-related infections, often associated with biofilm formation. We determined the bactericidal effect of 60% ethanol (ETOH) versus a 46.7% trisodium citrate (TSC) solution on biofilm embedded in silicone catheters. METHODS Four- and 24-h biofilms of Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans established in a microfermentor were exposed to ETOH and TSC for up to 24 h and the number of remaining viable microorganisms was determined. RESULTS ETOH 60% was significantly more effective than 46.7% TSC in rapidly eradicating sessile cells from all microorganisms tested. A 20-min ETOH 60% treatment completely eradicated the Gram-negative bacilli and C. albicans biofilms, which initially contained up to 10(8) and 10(5) cells, respectively. Gram-positive cocci biofilms only showed a significant 2.6-4.3 log reduction in the initial viable counts after 20 min of ETOH 60% treatment, with eradication occurring after 30 min. Confocal laser scanning microscopy observation of ETOH-treated biofilm showed sparse cells with respiratory activity. TSC 46.7% eradicated none of the tested microorganisms. In contrast, ETOH 60% totally eradicated planktonic cells, whereas TSC had significant bactericidal activity against K. pneumoniae, P. aeruginosa and C. albicans after 20 min, 1 and 24 h, respectively, but none on the Staphylococcus species. CONCLUSIONS This in vitro study demonstrates the superior antimicrobial activity of ETOH 60% in contrast to TSC 46.7% in eradicating biofilm formed on a silicon catheter. Hence, ethanol-based solution shows promise as a catheter lock solution.

Successful control of a hospital-wide vancomycin-resistant Enterococcus faecium outbreak in France

We describe the control of a hospital-wide vancomycin-resistant Enterococcus faecium (VRE) outbreak in a 2,000-bed university hospital located on three different sites in Clermont-Ferrand, France. From January 2004 to April 2007, 220 VRE cases were identified. Overall, 28 different wards had at least one case. All of the strains expressed a high level of resistance to vancomycin and to teicoplanin carried by the vanA gene. Pulsed-field gel electrophoresis (PFGE) analysis of the strains revealed that they were clonally related. Control measures consisted of implementing a strategy of VRE screening by rectal swab, reinforcing hand hygiene practices and taking contact precautions. Recommendations for a restricted use of specific antibiotics were sent to each physician. Alcohol-based handrubs were provided throughout the hospital and the staff underwent training for their use. Compliance with contact precautions, including the use of clean non-sterile gloves and single-use gowns, was reinforced. VRE cases were assigned systematically to a single-bed room. In October 2007, no new VRE carriage has been detected for 7 months and no clinical samples had been VRE-positive for 10 months. In conclusion, a hospital-wide VRE outbreak was successfully controlled by a strategy based on routine screening, the reinforcement of hand hygiene and taking barrier precautions.

Bloodstream infection after positive catheter cultures: What are the risks in the intensive care unit when catheters are routinely cultured on removal?

Objectives: The aim of the study was to assess whether an isolated positive catheter culture is predictive of a subsequent bloodstream infection in intensive care unit patients. Design: Retrospective clinical study between 2000 and 2007. Setting: Intensive care unit of a university hospital. Subjects: All arterial, central venous, and dialysis catheters yielding selected pathogenic microorganisms from isolated positive catheter cultures. Positive catheter culture was defined by a catheter tip culture performed with the Brun-Buisson technique yielding ≥103 colony-forming units/mL; isolated positive catheter culture by a positive catheter culture without concomitant bloodstream infection due to the microorganism of the positive catheter culture evidenced within 48 hrs before or after catheter removal; and subsequent bloodstream infection by a bloodstream infection developing between 48 hrs and 30 days after catheter removal and due to a selected pathogenic microorganism of an isolated positive catheter culture. Active antibiotic therapy was active if at least one of the antibiotics administered was effective against the selected pathogenic microorganism of the positive catheter culture. Intervention: None. Measurement and Main Results: The end point of the study was the ratio of the number of subsequent bloodstream infections to that of selected pathogenic microorganisms isolated from positive catheter culture 30 days after catheter removal. A total of 138 isolated positive catheter cultures for 149 selected pathogenic micro-organisms was included in the study. Only two cases (1.3%) of subsequent bloodstream infection were evidenced, one resulting from Escherichia coli and the other from Staphylococcus epidermidis. The incidence of subsequent bloodstream infection did not differ with regard to the presence or absence of active antibiotics at catheter removal: zero of 23 vs. two of 121 (p = 1), respectively. Conclusions: Our results suggest that the risk of subsequent bloodstream infection in intensive care unit patients when the Brun-Buisson technique is used to define isolated positive catheter culture is low.

Fabrication of Acrylonitrile-Butadiene-Styrene Nanostructures with Anodic Alumina Oxide Templates, Characterization and Biofilm Development Test for Staphylococcus epidermidis

Medical devices can be contaminated by microbial biofilm which causes nosocomial infections. One of the strategies for the prevention of such microbial adhesion is to modify the biomaterials by creating micro or nanofeatures on their surface. This study aimed (1) to nanostructure acrylonitrile-butadiene-styrene (ABS), a polymer composing connectors in perfusion devices, using Anodic Alumina Oxide templates, and to control the reproducibility of this process; (2) to characterize the physico-chemical properties of the nanostructured surfaces such as wettability using captive-bubble contact angle measurement technique; (3) to test the impact of nanostructures on Staphylococcus epidermidis biofilm development. Fabrication of Anodic Alumina Oxide molds was realized by double anodization in oxalic acid. This process was reproducible. The obtained molds present hexagonally arranged 50 nm diameter pores, with a 100 nm interpore distance and a length of 100 nm. Acrylonitrile-butadiene-styrene nanostructures were successfully prepared using a polymer solution and two melt wetting methods. For all methods, the nanopicots were obtained but inside each sample their length was different. One method was selected essentially for industrial purposes and for better reproducibility results. The flat ABS surface presents a slightly hydrophilic character, which remains roughly unchanged after nanostructuration, the increasing apparent wettability observed in that case being explained by roughness effects. Also, the nanostructuration of the polymer surface does not induce any significant effect on Staphylococcus epidermidis adhesion.

Comparative study of 2 oral care protocols in intensive care units

HighlightsOral chlorhexidine and tooth brushing improved oral health scores in ICU patients.Increased caregiver satisfaction with an easy and simple oral care protocol.Decreased VAP rates with an oral chlorhexidine and tooth brushing protocol. Background: The quality of oral care is important in limiting the emergence of ventilator‐associated pneumonia (VAP) in intubated patients. Our main objective was to measure the quality improvement in oral care following the implementation of a new oral care protocol. We also monitored VAP rates. Material/methods: This was a cohort study of patients in 5 adult ICUs covering different specialties. During period 1, caregivers used a foam stick for oral care and during period 2 a stick and tooth brushing with aspiration. Oral chlorhexidine was used during both periods. The caregivers rated improvement in oral health on the basis of 4 criteria (tongue, mucous membranes, gingivae, and teeth). Caregiver satisfaction was also assessed. The incidence of VAP was monitored. Results: A total of 2,030 intubated patients admitted to intensive care units benefited from oral care. The patient populations during the 2 periods were similar with regard to demographic data and VAP potential risk factors. Oral health was significantly better from the third day of oral care in period 2 onward (period 1, 6.4 ± 2.1; period 2, 5.6 ± 1.8; P = .043). Caregivers found the period 2 protocol easier to implement and more effective. VAP rates decreased significantly between the 2 periods (period 1, 12.8%; period 2, 8.5%; P = .002). Conclusions: Our study showed that the implementation of a simple strategy improved the quality of oral care of patients in intensive care units, and decreased VAP rates.