Study of plastic fragments of beaches of Las Palmas de Gran Canaria as resistant bacteria reservoirs

Abstract

Plastic pollution is an issue of growing global concern. Although the mechanisms by which this waste causes direct damage to marine life are well documented (ingestion and entanglement), little is known about the indirect impact of plastics on the environment and public health. Recent studies have demonstrated the ability of plastic debris as a reservoir of potentially pathogenic bacteria, including antibiotic-resistant bacteria. Here, plastic pollution in the oceans worldwide, including the direct and indirect impact of plastic debris on marine biota, is reviewed. The particular situation of the Canary Islands is also revised. In addition, a small study was conducted with the aim of analysing the presence of antibiotic-resistant bacteria on the Canary Islands' coasts, focusing on coliforms due to their role as indicators of faecal contamination. Using samples of meso (25 mm – 5 mm) and microplastics (< 5 mm), sand and water from four different beaches of Las Palmas de Gran Canaria, four growth mediums (MacConkey, Blood Agar, Sabouraud and BairdParker) were cultivated. Growth was obtained in 4/5 plastic samples, 2/4 sand samples and 1/4 water samples. At the same time, PCRs of the intergenic region between the 16S and 23S rRNA genes were performed, obtaining negative results in all samples. Nine antibiotics were tested using the Kirby-Bauer method (Amoxicillin-Clavulanic, Cephalaxin, Clarithromycin, Doxycycline, Enrofloxacin, Lincomycin, Nalidixic Acid, Nitrofurantoin and Tetracycline) and resistance was found in all strains isolated for four of them (Amoxicillin-Clavulanic, Cephalaxin, Clarithromycin and Lincomycin). On the other hand, the antibiotics that showed the greatest susceptibility were Doxycycline, Enrofloxacin and Tetracycline.