Les bactéries productrices de bêtalactamases à spectre étendu : étude au centre hospitalo-universitaire de Strasbourg

[Experimental studies of long-term effect of a detergent disinfecting for surface on a strain of Escherichia coli]

We offer three complementary, original methods and reproducibles to study the antibacterial and long-term effect of a detergent disinfecting for surfaces commercialized lately in France. Long-term activity noticed-effect is compared with that of other products. We first study the curves of growth of a strain of Escherichia coli put in presence with the surface of the wells of a microplate beforehand and for several days (from D-10 to D0), coated with disinfecting detergents. Another method consisted on surfaces firstly treated from D-10 to D0 by the one or the other product to be tested, which are artificially contaminated in a standardized manner by a velvet footprint with a suspension of E. coli. The surviving microbes are counted after transfer on a Rodac plate. Finally, doorhandles are cleaned and disinfected with the product. The natural bacterial recolonization doorhandles is studied by daily Rodac plate within a week. These studies allow to prove that Bacoban introduces a bactericidal activity on E. coli with an long-term effect for at least 10 days. The most competitive products have a bacteriostatic effect during nine to 10 days, but bactericidal effect only during two days. This bactericidal long-term effect may be particularly interesting in hospital hygiene for the biocleaning of the most manipulated surfaces and should restrict the role of bacterial reservoir of certain surfaces participating in care or near of the patients.

Molecular diversity of Proteus mirabilis isolates producing extended-spectrum β-lactamases in a French university hospital

Between February 1997 and December 2002, 3340 hospitalised patients yielded samples positive for Proteus mirabilis, of whom 45 (1.3%) were colonised/infected by P. mirabilis producing extended-spectrum beta-lactamases (ESBLs). The gross incidence of patients colonised/infected by ESBL-producing P. mirabilis was 1.61/10(5) days of hospitalisation, with 20% of isolates being collected from patients in urology wards, most frequently (53.3%) from urine samples. Seventeen (37.7%) of the 43 isolates were obtained from samples collected within 48 h of hospitalisation, indicating that they were community-acquired. Isoelectric focusing assays and sequencing identified the TEM-24, TEM-92 and TEM-52 ESBLs. Pulsed-field gel electrophoresis revealed eight pulsotypes (I-VIII), with the two most common pulsotypes, IV and VI, comprising ten (23.3%) and 12 (26.6%) isolates, respectively. These pulsotypes were considered to represent epidemic strains and spread in various wards of the hospital.