h For decades, third-generation cephalosporins (3GC) have been major drugs used to treat infections due to Enterobacteriaceae; growing resistance to these antibiotics makes the rapid detection of such resistance important. The ␤Lacta test is a chromogenic test developed for detecting 3GC-resistant isolates from cultures on solid media within 15 min. A multicenter prospective study conducted in 5 French and Belgian hospitals evaluated the performance of this test on clinical isolates. Based on antibiotic susceptibility testing, strains resistant or intermediate to cefotaxime or ceftazidime were classified as 3GC resistant, and molecular characterization of this resistance was performed. The rates of 3GC resistance were 13.9% (332/2,387) globally, 9.4% in Escherichia coli (132/1,403), 25.6% in Klebsiella pneumoniae (84/328), 30.3% in species naturally producing inducible AmpC betalactamases (109/360), and 5.6% in Klebsiella oxytoca and Citrobacter koseri (7/124). The sensitivities and specificities of the ␤Lacta test were, respectively, 87.7% and 99.6% overall, 96% and 100% for E. coli and K. pneumoniae, and 67.4% and 99.6% for species naturally producing inducible AmpC beta-lactamase. False-negative results were mainly related to 3GC-resistant strains producing AmpC beta-lactamase. Interestingly, the test was positive for all 3GC-resistant extended-spectrum beta-lactamaseproducing isolates (n ‫؍‬ 241). The positive predictive value was 97% and remained at >96% for prevalences of 3GC resistance ranging between 10 and 30%. The negative predictive values were 99% for E. coli and K. pneumoniae and 89% for the species producing inducible AmpC beta-lactamase. In conclusion, the ␤Lacta test was found to be easy to use and efficient for the prediction of resistance to third-generation cephalosporins, particularly in extended-spectrum beta-lactamase-producing strains.

Blood culture (BC) efficiency is critical for the diagnosis of bloodstream infection (BSI). We evaluated the impact on standard care of implementing the new BacT/ALERT® FAPlus and FNPlus BC bottles containing antibiotic-binding polymeric beads. We measured positivity rates and time to detection (TTD) during the first 10 months of implementation (PF) and during the previous 10-month period (PS) during which we were using standard aerobic (SA) or standard anaerobic (SN) BC bottles. For each period, the same number of consecutive patients (n = 3,918) was included. Per patient, a median of 1 BC set (1 aerobic and 1 anaerobic bottles) has been sampled. A higher positivity rate was measured during PF than PS when counting per BC bottle (7.0 % vs 5.8 % with 1,456 and 1,237 positive bottles respectively, P < 0.0001) and per BC set (9.6 % vs 7.8 % with 995 and 832 positive BC sets respectively, P < 0.0001). In PF, an increased number of cases due to staphylococci (P < 0.0001) and to Gram-negative bacilli (P < 0.005) was observed, whereas the contamination rate was similar during the two periods (2.4 % of BC sets in PF and 2.3 % in PS). Although antibiotic consumption and medical activity were similar during the two periods, BSI case detection increased from 2.2 to 2.6 per 1,000 hospital-days, especially in intensive care units (ICU; 35.1 to 55.7). Mean TTD for pathogenic microorganisms was significantly shorter in PF than in PS (15.5 h vs 18.0 h, P < 0.01). In conclusion, the use of the new FAPlus/FNPlus BC bottles improved the diagnosis of bacteremia in our hospital, especially in ICU patients.