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

• Published in: European journal of clinical microbiology & infectious diseases Vol. 35; no. 12; pp. 2047 - 2051
• Main Authors: Pardo, C.-A., Tan, R. N., Hennequin, C., Beyrouthy, R., Bonnet, R., Robin, F.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2016; Springer Nature B.V; Springer Verlag
• Subjects: Anti-Bacterial Agents - metabolism; Anti-Bacterial Agents - pharmacology; Antibiotics; Bacteriological Techniques - methods; Biomedical and Life Sciences; Biomedicine; Biotransformation; Drug Resistance, Bacterial; Enterobacteriaceae; Enterobacteriaceae - drug effects; Enterobacteriaceae - metabolism; Genes; Human health and pathology; Internal Medicine; Ionization; Lasers; Life Sciences; Medical laboratories; Medical Microbiology; Methods; Mutation; Norfloxacin - metabolism; Norfloxacin - pharmacology; Original Article; Polymerase chain reaction; Sensitivity and Specificity; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Time Factors; France; Tobramycin; Ofloxacin; Norfloxacin; Nalidixic Acid; Quinolones; flight mass-spectrometry; fluoroquinolone-modifying enzyme; prevalence; identification; desorption ionization-time; quinolone resistance gene; united-states; carbapenemases; ciprofloxacin
• ISSN: 0934-9723; 1435-4373
• DOI: 10.1007/s10096-016-2762-1

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.