Rapid detection of AAC(6')-Ib-cr production using a MALDI-TOF MS strategy

Eur J Clin Microbiol Infect Dis. 2016 Dec;35(12):2047-2051. doi: 10.1007/s10096-016-2762-1. Epub 2016 Aug 24.

Abstract

Plasmid-mediated quinolone resistance mechanisms have become increasingly prevalent among Enterobacteriaceae strains since the 1990s. Among these mechanisms, AAC(6')-Ib-cr is the most difficult to detect. Different detection methods have been developed, but they require expensive procedures such as Sanger sequencing, pyrosequencing, polymerase chain reaction (PCR) restriction, or the time-consuming phenotypic method of Wachino. In this study, we describe a simple matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) method which can be easily implemented in clinical laboratories that use the MALDI-TOF technique for bacterial identification. We tested 113 strains of Enterobacteriaceae, of which 64 harbored the aac(6')-Ib-cr gene. We compared two MALDI-TOF strategies, which differed by their norfloxacin concentration (0.03 vs. 0.5 g/L), and the method of Wachino with the PCR and sequencing strategy used as the reference. The MALDI-TOF strategy, performed with 0.03 g/L norfloxacin, and the method of Wachino yielded the same high performances (Se = 98 %, Sp = 100 %), but the turnaround time of the MALDI-TOF strategy was faster (<5 h), simpler, and inexpensive (<1 Euro). Our study shows that the MALDI-TOF strategy has the potential to become a major method for the detection of many different enzymatic resistance mechanisms.

MeSH terms

  • Anti-Bacterial Agents / metabolism*
  • Anti-Bacterial Agents / pharmacology
  • Bacteriological Techniques / methods*
  • Biotransformation*
  • Drug Resistance, Bacterial*
  • Enterobacteriaceae / drug effects*
  • Enterobacteriaceae / metabolism
  • Norfloxacin / metabolism*
  • Norfloxacin / pharmacology
  • Sensitivity and Specificity
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Time Factors

Substances

  • Anti-Bacterial Agents
  • Norfloxacin