RESUMO
In food safety implementation, bacterial inactivation is an imperative aspect of hygiene and sanitation. Studies on lithium magnesium silicate (LMS) hydrosol incorporated with slightly acidic electrolyzed water (SAEW) for decontamination of pathogenic bacteria are limited. This present study aimed to investigate the bactericidal efficacy of LMS hydrosol incorporated with SAEW against Escherichia coli. Optimum combination conditions of SAEW, hydrosol concentration, and available chlorine concentration (ACC) were optimized by response surface methodology under the central composite design against the growth of E. coli. The optimum combination conditions of exposure time, hydrosol concentration, and ACC were 9.5 minutes, 1.7%, and 20.5 ppm, respectively. The results showed that the increase in ACC led to inactivation in the survival of E. coli compared with the control (p<0.05). It can be concluded that the best combination percentage between SAEW and hydrosol ranged from 1.5-1.7%, in which E. coli was reduced by 4.50 log10 CFU/mL at an ACC of 9.94 ppm. When increasing the ACC to 14.84 ppm, E. coli was reduced by 4.51 log10 CFU/mL compared with the initial number of bacteria (8.20 log10 CFU/mL) in the control group. The number of bacteria was undetected after increasing ACC to 19.93, 25.15, and 29.88 ppm at 10 min. This study suggests that LMS hydrosol incorporated with SAEW could potentially be used as an effective sanitizer.
RESUMO
The prevalence of staphylococcal infection and the emergence of multidrug resistance of Staphylococcus aureus (S. aureus) are major concerns in food safety and public health. This study aimed to investigate the prevalence of S. aureus isolated from traditional Chinese Rubing and Rushan cheese, antimicrobial resistance profiles, genomic characteristics, and predict antimicrobial resistance genes (ARGs). From 124 samples, 18 of 62 (29.03%) of Rubing and 5 of 62 (8.06%) of Rushan cheese were confirmed to be S. aureus positive by standard culture-based methods. Twenty-three coagulase-positive staphylococci isolates were grouped into 16 clusters by pulsed-field gel electrophoresis and subjected to routine susceptibility testing to 12 antibiotics. Those isolates exhibited high resistance to penicillin (100%), erythromycin, trimethoprim-sulphamethoxazole (34.78%), oxacillin, clindamycin, and cefoxitin (21.74%). Multidrug-resistant (MDR) S. aureus was found in 34.78% (8 of 23) of isolates. Further, S. aureus strain DC.RB_015 isolated from Rubing cheese, recognized as the most resistant to six antibiotics, was selected for whole-genome sequencing (WGS), continued with in silico approaches. S. aureus DC.RB_015 had a single chromosome size of 2,794,578 bp and a plasmid size of 22,961 bp. The strain harbored 18 predicted ARGs, including eight efflux pump genes (mepA, tet(K), arlR, arlS, norA, mgrA, tet(38), LmrS), one peptidoglycan biosynthesis gene (bacA), two ß-lactams resistance genes (mecA, blaZ), and seven genes conferring other antimicrobial resistance (APH(3')-IIIa, aad(6), ErmB, SAT-4, mecR1, GlpT, murA). The results of this study expand the knowledge of S. aureus strain DC.RB_015, increase food safety awareness, and will be helpful in establishing therapeutic therapy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-03072-4.
