Alteration of Drug-Resistant Proteins in ESBL-Producing Escherichia coli After Induction with Cefoxitin Using MALDI-TOF Technique

Abstract This study aimed to solve the diagnostic problem of AmpC enzyme production from ESBL production of community-acquired urinary tract-infected Escherichia coli from Maharaj Nakorn Chiang Mai Hospital in 2019-2020 by using the MALDI-TOF technique to search for the significant difference between the ceftazidime exposure alone and the concomitance of ESBL inhibitor, clavulanic acid, and AmpC inducer, cefoxitin. Among 254 E. coli isolates, 42.12% (n = 107) were categorized as high-ESBL producers after determined by E-strip test. The frequencies of six peaks, 2689 (88.19%), 3126 (90.55%), 6314 (91.73%), 6411 (88.98%), 7157 (90.55%), 10301 (85.09%) Da were suspected to be the E. coli specific peptide spectra. In the high-ESBL-producing group, three statistically significant peptide spectra which played an ESBL manner were only identified at 4613 (13.33%, P = 0.008), 5613 (11.67%, P = 0.018), and 9713 (55.00%, P < 0.001) Da. Three peptide spectra that acted in AmpC β-lactamase manner were statistically significant at 4184 (16.67%, P = 0.048), 9551 (10.00%, P = 0.021), and 10477 Da (38.33%, P = 0.006) in this group. Whereas the statistically significant peptide spectra which played as AmpC were identified at 5380 (80.00%, P = 0.005) and 6254 Da (66.67%, P = 0.016) in the non ESBL-producing group. Our results indicated that AmpC enzyme-related spectra could be detected in some high-ESBL and non ESBL-producing isolates after being induced by cefoxitin. Keywords: AmpC, MALDI-TOF, Cefoxitin, ESBL-producing E. coli, Drug resistance protein