Ceftizoxime Sodium

Microbe-mediated iron cycling plays a pivotal role in biogeochemical processes. However, the impact of trace-level antibiotics on microbially mediated dissimilatory iron reduction (DIR) remains unexplored. In this study, we investigated the effects of four typical antibiotics on DIR mediated by Shewanella oneidensis MR-1, with a focus on their inhibitory effects on three extracellular electron transfer (EET) pathways: 1) direct EET, 2) soluble redox mediator-dependent EET, and 3) nanowire-mediated EET. Our findings demonstrate a concentration-dependent decline in DIR activity with increasing ceftizoxime concentrations, culminating in complete suppression at 64 μg/L. Polymyxin disrupts the cell membrane, causing structural damage that subsequently impairs the electron transport chain (ETC), leading to a reversible reduction in DIR activity. In contrast, ofloxacin and tetracycline directly down-regulated genes associated with electron production and transfer, thereby suppressing both electron transport system activity and the synthesis of NADH dehydrogenase and c-type cytochromes. This irreversibly disrupts ETC function, blocking S. oneidensis MR-1 from conducting EET and impairing DIR activity. This finding reveals antibiotic-induced alterations in microbial iron metabolism and provides new insights into their potential impact on the environmental iron cycling.

With the spread of antibiotic resistance genes such as blaCTX-M-2, dfrA1 and blaNDM-1, the problem of drug resistance in E. coli is becoming increasingly serious [1]. This study aimed to identify integrons genes and MGEs in E. coli isolated from migratory birds' feces at Poyang Lake, Jiangxi Province, focusing on their role in antimicrobial resistance (AMR). The 114 isolated E. coli strains were tested by standard disk diffusion method and genetic testing method. Results showed 64.04 % (73/114) of isolates were multi-drug resistance (MDR), mainly resistant to 3-6 antibiotics. Common resistances included neomycin (50 %) and streptomycin (48.25 %). We detected 21 mobile genetic elements, including IS903 (92.11 %), traA (72.81 %), ISCR3 (64.91 %), and ISpa7 (50 %). These elements were present in all isolates, forming 112 combinations. Significant differences in resistance rates were found between class I integron-positive and negative strains for doxycycline, tetracycline, bacitracin, and streptomycin (P < 0.01), and for neomycin (P < 0.05). Class II integron-positive bacteria showed higher resistance to doxycycline (P < 0.01) and ceftizoxime (P < 0.05). No significant differences were observed for class III integron-positive strains. This study underscores the prevalence of multidrug-resistant and the diversity of mobile genetic elements in E. coli, emphasizing the need for continuous monitoring.