Analysis of the Degradation of Broad-Spectrum Cephalosporins by OXA-48-Producing Enterobacteriaceae Using MALDI-TOF MS.

Marina Oviaño,María Rosario Rodicio,Germán Bou,Jürgen J Heinisch,Rosaura Rodicio,Javier Fernández

doi:10.3390/microorganisms7120614

Abstract

The objective of the study was to evaluate the activity of OXA-48 against different broad-spectrum cephalosporins and to identify the reaction products by MALDI-TOF MS. The action of OXA-48 on cefotaxime, ceftazidime, and ceftriaxone was assessed by this method, using an Escherichia coli J53 transconjugant carrying only the ~62 Kb IncL plasmid containing the blaOXA-48 gene, and the same strain without any plasmid was included as a negative control. In addition, a collection of 17 clinical OXA-48-producing Enterobacteriaceae, which were susceptible to broad-spectrum cephalosporins, was evaluated. MALDI-TOF MS-based analysis of the E. coli transconjugant carrying the blaOXA-48-harboring plasmid, and also the clinical isolates, showed degradation of cefotaxime into two inactive compounds—decarboxylated and deacetylated cefotaxime (~370 Da) and deacetyl cefotaxime (~414 Da), both with the hydrolyzed beta-lactam ring. Reaction products were not obtained when the experiment was performed with ceftriaxone or ceftazidime. From a clinical point of view, our study supports the idea that the efficacy of cefotaxime against OXA-48-producing Enterobacteriaceae is doubtful, in contrast to ceftazidime and ceftriaxone which could be valid choices for treating infections caused by these bacteria. However, further clinical studies confirming this hypothesis are required.

Highlights

The oxacillinases comprise a heterogeneous group of class D β-lactamases that are able to hydrolyze amino- and carboxypenicillins and, for some members of the group, cephalosporins and carbapenems to a greater or lesser extent [1,2]
Since at least some cephalosporins may be a possible alternative for the treatment of invasive infections caused by OXA-48-producing Enterobacteriaceae, the aim of the present study was to evaluate the activity of OXA-48 against three commonly used broad-spectrum cephalosporins, for which data are still limited or unavailable, and to analyze the reaction products, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)
The present study confirmed the degradation of cefotaxime by the OXA-48 enzyme, providing further evidence to rule out the use of this antibiotic for the treatment of OXA-48-producing Enterobacteriaceae

Summary

Introduction

The oxacillinases comprise a heterogeneous group of class D β-lactamases that are able to hydrolyze amino- and carboxypenicillins and, for some members of the group, cephalosporins and carbapenems to a greater or lesser extent [1,2]. Therapeutic options against infections caused by carbapenemase-producing Enterobacteriaceae are scarce and these bacteria represent a major threat for patient safety worldwide [6]. OXA-48 and its variants, with the exception of OXA-163, hydrolyze carbapenems at low level, but do not confer resistance to broad-spectrum cephalosporins in contrast to other carbapenemases whose activity against these drugs is well known [2,4]. From the point of view of clinical efficacy, in vivo experiments in mice evidenced that therapy with ceftazidime was effective against OXA-48-producing Enterobacteriaceae lacking extended-spectrum beta-lactamases (ESBLs) or AmpC-like β-lactamases, whereas the therapy with cefotaxime had little impact in reducing lethality of the rodents [8,9]

Objectives

Methods

Conclusion