TITLE:
Anthropogenic Drivers of Antibiotic Resistance in Aerococcus viridans from Urban Mangrove Waters of Grand Libreville (Gabon): Environmental and Public Health Implications
AUTHORS:
Davhys Tresor Kassa-Kassa, Pierre Philippe Mbehang Nguema, Emelie Arlette Apinda Legnouo, Saint Bickolard Mabicka Iwangou, Aubin Armel Koumba, Jean Constant Obague Mbeang, Guy-Roger Ndong Atome, Christophe Roland Zinga Koumba
KEYWORDS:
Mangrove Wastewaters, Aerococcus viridans, Antibiotic Resistance, Anthropogenic Pressures, Health Risks
JOURNAL NAME:
Journal of Environmental Protection,
Vol.17 No.9,
September
30,
2026
ABSTRACT: Mangrove waters are essential ecosystems, serving as nurseries for fish and crustaceans. Investigating bacterial antibiotic resistance in these waters is crucial for assessing potential risks to human health and the safety of food resources derived from these environments. This study highlights the antibiotic resistance profiles associated with Aerococcus viridans strains isolated from mangrove waters in Grand Libreville, Gabon, and examines their geographical variability. The study was conducted from July to September 2025 across nine urban mangrove sites within the four municipalities that make up Grand Libreville: Ambowe, Ondongo, Rouger, Alenakiri, Lowe, Bizango, Angondje, Ozoughe, and Okala. Water samples were collected at low tide from five sampling points per site, yielding a total of 45 wastewater samples. Bacterial cultures were performed on D-Cococcel agar (BioMérieux, France) at 37.0 ± 0.5˚C for 48 hours. Each colony underwent Gram staining, as well as oxidase and catalase testing. Biochemical identification was carried out using API 20 Strep galleries (BioMérieux, France). Antibiotic susceptibility testing was performed using the Kirby-Bauer disk diffusion method with fourteen antibiotic discs. The prevalence of antibiotic resistance was highest for penicillin (100%) and erythromycin (60%), representing a potential public health risk. Moreover, resistance patterns exhibited notable geographical disparities. Higher resistance levels and multidrug resistance scores were observed in sites exposed to multiple sources of anthropogenic pollution, particularly Lowe (76.2%) and Ambowe (61.9%). In contrast, lower resistance levels and multidrug resistance scores were recorded in Okala (16.6%) and Alenakiri (10.71 %), where human activities are less intense. These findings suggest that anthropogenic activities contribute to the contamination of mangrove waters in Lowe and Ambowe. Although the overall situation does not appear alarming, identified hotspots of resistance, as well as intermediate zones such as Bizango, Rouger, and Ozoughe, warrant continued monitoring.