Department of Bacteriology-Hygiene, Bicêtre Hospital, Assistance Publique - Hôpitaux de Paris, Le Kremlin-Bicêtre, France.
UMR-S 1184, Paris-Saclay University, Le Kremlin-Bicêtre, France.
J Antimicrob Chemother. 2020 Aug 1;75(8):2120-2123. doi: 10.1093/jac/dkaa155.
OXA-244, a single amino acid variant of OXA-48, demonstrates weaker hydrolytic activity towards carbapenems and temocillin compared with OXA-48. Of note, these antimicrobials are present in high concentrations in several carbapenemase-producing Enterobacterales (CPE) screening media. As a result, some screening media fail to grow OXA-244-producing isolates, while the prevalence of OXA-244 producers is constantly increasing in France.
Here, we evaluate the performance of three commercially available CPE screening media [ChromID® CARBA SMART (bioMérieux), Brilliance™ CRE (Thermo Fisher) and mSuperCARBA™ (MAST Diagnostic)] for their ability to detect OXA-244 producers (n = 101). As OXA-244 producers may also express an ESBL, two additional ESBL screening media were tested (Brilliance™ ESBL and ChromID® BLSE). MICs of temocillin and imipenem were determined by broth microdilution. The clonality of OXA-244-producing Escherichia coli isolates (n = 97) was assessed by MLST.
Overall, the sensitivity of the ChromID® CARBA SMART, Brilliance™ CRE and mSuperCARBA™ media were 14% (95% CI = 8.1%-22.5%), 54% (95% CI = 43.3%-63.4%) and 99% (95% CI = 93.8%-100%), respectively, for the detection of OXA-244 producers. Among the 101 OXA-244-producing isolates, 96% were E. coli and 77%-78% grew on ESBL screening media. MLST analysis identified five main STs among OXA-244-producing E. coli isolates: ST38 (n = 37), ST361 (n = 17), ST69 (n = 12), ST167 (n = 11) and ST10 (n = 8).
Our results demonstrated that the mSuperCARBA™ medium is very efficient in the detection of OXA-244 producers, unlike the ChromID® CARBA SMART medium. The high prevalence of ESBLs among OXA-244 producers allowed detection of 77%-78% of them using ESBL-specific screening media.
OXA-244 是 OXA-48 的一个单一氨基酸变异体，与 OXA-48 相比，对碳青霉烯类和替莫西林的水解活性较弱。值得注意的是，这些抗生素在几种产碳青霉烯酶肠杆菌科（CPE）筛选培养基中浓度很高。因此，一些筛选培养基无法生长产生 OXA-244 的分离株，而 OXA-244 产生者在法国的患病率却在不断增加。
在这里，我们评估了三种市售 CPE 筛选培养基 [ChromID® CARBA SMART（生物梅里埃）、Brilliance™ CRE（赛默飞世尔）和 mSuperCARBA™（MAST 诊断）] 的性能，以检测产生 OXA-244 的分离株（n=101）。由于 OXA-244 产生者也可能表达 ESBL，因此还测试了两种额外的 ESBL 筛选培养基（Brilliance™ ESBL 和 ChromID® BLSE）。通过肉汤微量稀释法测定替莫西林和亚胺培南的 MIC。用 MLST 评估 97 株产生 OXA-244 的大肠埃希菌分离株的克隆性。
总体而言，ChromID® CARBA SMART、Brilliance™ CRE 和 mSuperCARBA™ 培养基检测 OXA-244 产生者的灵敏度分别为 14%（95%CI=8.1%-22.5%）、54%（95%CI=43.3%-63.4%）和 99%（95%CI=93.8%-100%）。在 101 株产生 OXA-244 的分离株中，96%为大肠埃希菌，77%-78%在 ESBL 筛选培养基上生长。MLST 分析在产生 OXA-244 的大肠埃希菌分离株中发现了五个主要 ST：ST38（n=37）、ST361（n=17）、ST69（n=12）、ST167（n=11）和 ST10（n=8）。
我们的结果表明，mSuperCARBA™ 培养基在检测 OXA-244 产生者方面非常有效，而 ChromID® CARBA SMART 培养基则不然。OXA-244 产生者中 ESBL 的高流行率允许使用 ESBL 特异性筛选培养基检测 77%-78%的分离株。
