Assessment of azithromycin-induced toxicity in Caenorhabditis elegans: Effects on morphology, behavior, and lipid metabolism

Antibiotics are indispensable in modern healthcare, playing a critical role in mitigating bacterial infections. Azithromycin is used to fight upper respiratory tract infections, however has potential toxic effects that remain inadequately understood. In our present study, azithromycin exposure to <i>Caenorhabditis elegans</i> led to significant physiological and behavioral change, with pronounced effects observed at the studied concentration. The study employs an N2 wild-type strain to examine key physiological and behavioral parameters within the worm. <i>C.elegans</i> were exposed to two concentrations of azithromycin (0.0038 and 0.00038 mg/ml) from the embryonic stage to the L4 stage for 48 hours. The study assessed key endpoints including body length, thrashing behavior, brood size, embryonic viability, lipid accumulation via Nile red staining, pharyngeal pumping rate, and response to 1-Nonanol (which assesses neurotransmitter function). Results showed that at 0.0038 mg/ml, azithromycin significantly reduced body length, increased progeny production, altered lipid deposition, delayed response to 1-Nonanol, and decreased feeding rates. Even at the lowest concentration (0.00038 mg/ml), changes in body length and lipid accumulation were observed. These findings suggest that the toxicity of azithromycin in <i>C.elegans</i> is dose-dependent and varies with exposure duration and developmental stage. Further research is needed to elucidate the molecular mechanisms underlying these toxic effects, particularly at environmentally relevant concentrations of azithromycin.