[Antimicrobial susceptibility of Clostridium difficile clinical isolates collected from 2001 to 2007 in a French university hospital]. / Etude de la sensibilité aux antibiotiques de souches cliniques de Clostridium difficile isolées de 2001 à 2007 au CHU Henri-Mondor, Créteil.

AIM: The aim of this study was to determine the antimicrobial susceptibilities of Clostridium difficile clinical isolates obtained from symptomatic patients suffering from diarrhoea. METHODS: In vitro activities of 22 antimicrobial agents were evaluated against 401 clinical isolates of C. difficile collected from patients hospitalized in a French university hospital (Henri Mondor hospital) between 2001 and 2007. The in vitro antibiotic susceptibility testing was performed using the disc diffusion method according to recommendations of the antibiogram committee of the French society for microbiology. RESULTS: All strains were found to be susceptible to metronidazole and vancomycin but resistant to clindamycin, gentamicin, and colistin. Most of them were susceptible to pristinamycin (97.8%), rifampin (94.8%), and chloramphenicol (97.3%), and variable degrees of resistance were found for erythromycin and spiramycin (72.8%), as well as for tetracycline (85.6%). Note that none of the strain was susceptible to ofloxacin, and that 80.5% of them showed a high-level resistance. For beta-lactams, all strains were resistant to tested cephalosporins, and nine isolates (2.2%) were also resistant to penicillins combined or not to a beta-lactamase inhibitor. Finally, 28 (7%) and 38 (9.5%) of tested strains were categorized intermediate and resistant to imipenem (with a heterogeneous aspect), respectively. CONCLUSION: All tested strains were found to be susceptible to metronidazole and vancomycin which remain antimicrobial agents for the treatment of infections caused by C. difficile.

[Comparison of three enzyme immunoassays for detection of Clostridium difficile toxins A and B]. / Comparaison de trois tests immunoenzymatiques pour la détection des toxines A et B de Clostridium difficile.

AIM OF THE STUDY: Diagnosis of Clostridium difficile-associated diarrhea is classically based on detection of toxin A and/or toxins A+B by using several techniques. However, these techniques show important differences in terms of sensitivity and specificity. In this work, we compared three commercial immunoenzymatic tests for detecting C. difficile toxins. METHODS: We used three immunoenzymatic techniques: ELISA Premiertrade mark Toxins A and B (Meridian), ImmunoCard (IC) Toxins A and B (Meridian), and Triage (TRI) Antigen GDH and Toxin A (Biosite). Culture on the specific media C. difficile (bioMérieux) was performed in parallel. RESULTS: During two years, 898 stool specimens have been tested by using the three different techniques. According to the manufacturer's recommendations (sample positive if optical density [OD] value greater or equal to 0.15), 205 (22.8%) were positive for ELISA. Among them, 65 (31.7%) were negative for all other tests, and they have been considered as false-positive results. This discrepancy led us to choose other OD values (greater than 0.75: positive result; 0.15-0.75: limit result). For limit results, IC, TRI, antigen GDH, and culture methods were positive in 30, 2, 41, and 29% of cases, respectively, whereas for positive results (>0.75), they were positive in 82, 54, 84, and 76% of cases, respectively. CONCLUSION: ELISA and IC tests are the most powerful and are concordant together if interpretation is performed with OD values redefined by the microbiology laboratory. The choice of the technique to use depends on the number of samples to analyze, the rapidity of the result, and the cost.

[Contribution of urinary pneumococcal antigen detection combined with the research of legionella antigen for diagnosis of pneumonia in hospitalized patients]. / Contribution de la recherche d'antigénurie pneumococcique couplée à celle d'antigénurie légionelle au diagnostic des pneumonies à l'hôpital.

AIM OF THE STUDY: Bacteriological confirmation of pneumonia (PNM) in hospitalized patients is often erratic or belated. Because of importance of prognosis, early adaptation of treatment requires an empirical antimicrobial therapy (generally aminopenicillin and macrolide combination). The starting therapeutic strategy should profit by a fast and reliable test asserting a pneumococcal etiology. The Binax Now S. pneumoniae (BNP) test allows an urinary pneumococcal antigen (UPA) detection using an immunochromatographic membrane assay within 15 minutes. MATERIALS AND METHODS: We first evaluated the BNP test for 28 patients with pneumococcal PNM proved by culture, and 118 negative control patients without PNM. The BNP test was then evaluated by testing urine from 158 hospitalized patients with a clinical picture of PNM (community-acquired: 90, nosocomial: 68) for whom a research of urinary Legionella antigen (Binax Now) was prescribed and was positive for only two cases. 57 patients (36.1%) were hospitalized in ICU. RESULTS: The sensitivity was 71.4% (85.7% for the 21 bacteriemic PNM), and the specificity was 98.3%; that is consistent with previous published data. Among the 158 patients with PNM, UPA was detected in 17 cases (10.8%): 15 within the community-acquired PNM (16.7%) and 2 (2.9%) within the nosocomial cases. The pneumococcal etiology was confirmed by bacteriological samples in 7/17 patients (6 by blood cultures). The 10 others showed clinical and radiological features in agreement with a pneumococcal PNM. Among the 141 patients with negative AUP, S. pneumoniae was isolated from 6 of them (2 in blood cultures). CONCLUSION: The Binax Now S. pneumoniae test allowed a fast and reliable etiological diagnosis in 10.8% of hospitalized PNM (16.7% of the community-acquired cases) having a research of urinary Legionella antigen (conceiving with severity factors). So it could conduce to an improved adjustment of the starting antimicrobial therapy of hospitalized adult patients with PNM.

Dissemination of CTX-M-type beta-lactamases among clinical isolates of Enterobacteriaceae in Paris, France.

We analyzed 19 clinical isolates of the family Enterobacteriaceae (16 Escherichia coli isolates and 3 Klebsiella pneumoniae isolates) collected from four different hospitals in Paris, France, from 2000 to 2002. These strains had a particular extended-spectrum cephalosporin resistance profile characterized by a higher level of resistance to cefotaxime and aztreonam than to ceftazidime. The bla(CTX-M) genes encoding these beta-lactamases were involved in this resistance, with a predominance of bla(CTX-M-15). Ten of the 19 isolates produced both TEM-1- and CTX-M-type enzymes. One strain (E. coli TN13) expressed CMY-2, TEM-1, and CTX-M-14. bla(CTX-M) genes were found on large plasmids. In 15 cases the same insertion sequence, ISEcp1, was located upstream of the 5' end of the bla(CTX-M) gene. In one case we identified an insertion sequence designated IS26. Examination of the other three bla(CTX-M) genes by cloning, sequencing, and PCR analysis revealed the presence of a complex sul1-type integron that includes open reading frame ORF513, which carries the bla gene and the surrounding DNA. Five isolates had the same plasmid DNA fingerprint, suggesting clonal dissemination of CTX-M-15-producing strains in the Paris area.