Oguadinma Ikechukwu, Mishra Abhinav, Dev Kumar Govindaraj
Center for Food Safety, The University of Georgia, Griffin, GA, United States.
Department of Food Science & Technology, The University of Georgia, Athens, GA, United States.
Front Microbiol. 2023 Apr 26;14:1059144. doi: 10.3389/fmicb.2023.1059144. eCollection 2023.
The occurrence of antibiotic resistant (ABR) bacteria in foods is a growing public health challenge. We evaluated sanitizer cross-tolerance among ABR () O157:H7 and non-O157:H7 Shiga-toxin producing (STEC) serogroups. Sanitizer tolerance in STEC could be a public health concern as mitigation strategies against the pathogen might be compromised.
Resistance to ampicillin and streptomycin were evolved in serogroups: O157:H7 (H1730, and ATCC 43895), O121:H19 and O26:H11. Resistance to antibiotics was evolved chromosomally through incremental exposure to ampicillin (amp C) and streptomycin (strep C). Transformation using a plasmid was performed to confer resistance to ampicillin to generate amp P strep C.
The minimum inhibitory concentration (MIC) of lactic acid for all strains evaluated was 0.375% v/v. Analysis of bacterial growth parameters in tryptic soy broth amended with 0.0625% v/v, 0.125% v/v, and 0.25% v/v (subMIC) lactic acid indicated that growth correlated positively with the lag phase duration, and negatively with both the maximum growth rate and change in population density for all strains evaluated except for the highly tolerant variant- O157:H7 amp P strep C. Strains O121 NR (non-ABR), O121 amp C, O121 amp P strep C, O157:H7 H1730 amp C and O157:H7 H1730 amp P strep C were not inactivated after exposure to 1% and 2.5% v/v lactic acid for 300 s. No recovery of cells was observed after the strains were exposed to 5% v/v lactic acid for 300 s. ABR strains O157:H7 H1730 amp C and O157: H7 H1730 amp P strep C demonstrated a high tolerance to lactic acid ( ≤ 0.05).
ABR in isolate O157: H7 H1730 may improve tolerance to lactic acid. Increased tolerance may be discerned by evaluating growth parameters of bacteria in presence of sub-MIC levels of lactic acid.
食品中抗生素抗性（ABR）细菌的出现是一个日益严峻的公共卫生挑战。我们评估了ABR大肠杆菌O157:H7和非O157:H7产志贺毒素大肠杆菌（STEC）血清型之间对消毒剂的交叉耐受性。STEC对消毒剂的耐受性可能会成为一个公共卫生问题，因为针对该病原体的缓解策略可能会受到影响。
在大肠杆菌血清型中诱导出对氨苄青霉素和链霉素的抗性：O157:H7（H1730和ATCC 43895）、O121:H19和O26:H11。通过逐步暴露于氨苄青霉素（amp C）和链霉素（strep C）在染色体上诱导产生对抗生素的抗性。使用质粒进行转化以赋予对氨苄青霉素的抗性，从而产生amp P strep C。
所评估的所有菌株对乳酸的最低抑菌浓度（MIC）为0.375% v/v。在添加了0.0625% v/v、0.125% v/v和0.25% v/v（亚MIC）乳酸的胰蛋白胨大豆肉汤中对细菌生长参数进行分析，结果表明，除高度耐受的变体O157:H7 amp P strep C外，所有评估菌株的生长与延迟期持续时间呈正相关，与最大生长速率和种群密度变化呈负相关。菌株O121 NR（非ABR）、O121 amp C、O121 amp P strep C、O157:H7 H1730 amp C和O157:H7 H1730 amp P strep C在暴露于1%和2.5% v/v乳酸300秒后未被灭活。在菌株暴露于5% v/v乳酸300秒后未观察到细胞复苏。ABR菌株O157:H7 H1730 amp C和O157:H7 H1730 amp P strep C对乳酸表现出高耐受性（P≤0.05）。
分离株O157:H7 H1730中的ABR可能会提高对乳酸的耐受性。通过评估在亚MIC水平乳酸存在下细菌的生长参数，可以发现耐受性的增加。
