Renvoisé Aurélie, Decré Dominique, Amarsy-Guerle Rishma, Huang Te-Din, Jost Christelle, Podglajen Isabelle, Raskine Laurent, Genel Nathalie, Bogaerts Pierre, Jarlier Vincent, Arlet Guillaume
Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Laboratory of Bacteriology-Hygiene, Paris, France.
J Clin Microbiol. 2013 Dec;51(12):4012-7. doi: 10.1128/JCM.01936-13. Epub 2013 Sep 25.
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 βLacta 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 beta-lactamases (109/360), and 5.6% in Klebsiella oxytoca and Citrobacter koseri (7/124). The sensitivities and specificities of the βLacta 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-lactamase-producing 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 βLacta 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.
几十年来，第三代头孢菌素（3GC）一直是治疗肠杆菌科细菌感染的主要药物；对这些抗生素的耐药性不断增加，使得快速检测这种耐药性变得很重要。βLacta检测是一种显色试验，用于在15分钟内从固体培养基上的培养物中检测耐3GC的分离株。在法国和比利时的5家医院进行的一项多中心前瞻性研究评估了该检测对临床分离株的性能。根据抗生素敏感性试验，对头孢噻肟或头孢他啶耐药或中介的菌株被分类为耐3GC，并对这种耐药性进行了分子特征分析。全球耐3GC的比率为13.9%（332/2387），大肠杆菌中为9.4%（132/1403），肺炎克雷伯菌中为25.6%（84/328），天然产生可诱导AmpCβ-内酰胺酶的菌种中为30.3%（109/360），产酸克雷伯菌和科氏柠檬酸杆菌中为5.6%（7/124）。βLacta检测的敏感性和特异性总体分别为87.7%和99.6%，大肠杆菌和肺炎克雷伯菌分别为96%和100%，天然产生可诱导AmpCβ-内酰胺酶的菌种为67.4%和99.6%。假阴性结果主要与产生AmpCβ-内酰胺酶的耐3GC菌株有关。有趣的是，该检测对所有耐3GC且产超广谱β-内酰胺酶的分离株（n = 241）均呈阳性。阳性预测值为97%，对于3GC耐药率在10%至30%之间的情况，阳性预测值保持在≥96%。大肠杆菌和肺炎克雷伯菌的阴性预测值为99%，产生可诱导AmpCβ-内酰胺酶的菌种的阴性预测值为89%。总之，发现βLacta检测易于使用，并且对于预测对第三代头孢菌素的耐药性很有效，特别是在产超广谱β-内酰胺酶的菌株中。
