Lead, silver nitrate and antibiotic resistance in bacteria isolated from Nile tilapia (Oreochromis niloticus) in anthropogenically polluted Lake Chivero, Zimbabwe

Abstract

Antibiotic and heavy metal-resistant pathogenic bacteria associated with fish from contaminated water can spread diseases. This study aims to identify antibiotics, lead, and silver nitrate-resistant bacteria in 180 fish samples from Lake Chivero using bacterial identification, disk-diffusion, and agar dilution methodologies. Of the identified 157 bacterial isolates, 46 (29.3%) were Staphylococcus, 35 (22.3%) were Escherichia coli, 26 (16.6%) were Aeromonas spp., 15 (9.6%) were Shigella spp., 13 (8.3%) were Bacillus cereus, 12 (7.6%) were Edwardsiella tarda, 7 (4.5%) were Proteus mirabilis, and 3 (1.9%) were Listeria spp. Gentamicin was the most effective, with 100% of the bacterial species susceptible, followed by neomycin (68.2%), tetracycline (56.7%), cloxacillin (52.2%), streptomycin (51%), erythromycin (32.6%), lincomycin (15.3%), and rifampicin (13.4%). For the eight taxa investigated, the multiple antibiotic resistance (MAR) index ranged from 0.50 to 0.88, with all values greater than 0.2. E. Coli and Proteus spp. had the highest MAR index values (0.88 each), followed by Bacillus, Aeromonas, and Staphylococcus (0.75 each), and Listeria, Edwardsiella, and Shigella (0.63 each). The isolated bacteria were multidrug-resistant, with varying resistance levels to lead and silver nitrate, with silver nitrate resistance rates ranging from 23.1–88.5% and lead resistance rates ranging from 30.8–69.2%. The multidrug resistance (MDR) pathogenic bacteria are found in fish from contaminated Lake Chivero, posing a health risk to humans. As a result, adequate waste disposal is required, as is multi-sectoral monitoring of antimicrobial resistance (AMR) and public education about the health risks associated with fish and fish-derived products.

Keywords:

• fish
• pathogenic bacteria
• antimicrobial resistance
• heavy metal resistance

PUBLIC INTEREST STATEMENT

Antibiotics and heavy metals water pollution has lately been a major cause of concern throughout the world, resulting in microbes that are resistant to a variety of medications. However, antibiotic- and heavy metal-resistant pathogenic bacteria linked with aquatic species like fish have the potential to transmit illnesses. As a result, this study examines the human pathogenic bacteria associated with Nile tilapia (Oreochromis niloticus) in a heavy metal and antibiotic-polluted environment (Lake Chivero) and assesses their resistance to lead, silver nitrate, and antibiotics. According to the findings, anthropogenic metals and antimicrobial residues have a crucial role in the development of resistance among bacteria linked with aquatic life. These drug-resistant microbes might have a significant influence on antibiotic therapeutic efficacy in aquatic organisms, humans, and other animals. To reduce the acquisition and spread of antibiotic resistance, thorough multi-sectoral monitoring, proper waste disposal, and public education are strongly advised.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

Claudious Gufe

Claudious Gufe, the first author, is an experienced Laboratory Technologist with a demonstrated history of working in the veterinary industry. Strong research professional with a Bsc Hononurs in Biological Sciences focused in Biological Sciences from Midlands State University and MSc in Tropical animal health, Institute of Tropical medicine, Antwerp Belgium, collaborating with University of Pretoria, South Africa. He is currently a PhD student.

Jerikias Marumure

Jerikias Marumure, the third author, a lecturer and researcher at Great Zimbabwe University. Completed his Bachelor of Science in Biological Sciences from the Bindura University of Science Education, and completed his Masters of Science in Applied Microbiology and Biotechnology from National University of Science and Technology in Zimbabwe. Currently a PhD student at University of South Africa, working on antibacterial resistance and the efficacy of antidiarrhoeal plants against cholera.

Bothwell Karembera, the second author, is biologist and a graduate of BSc honours Biological Sciences from the University of Zimbabwe.

Zakio Makuvara

Zakio Makuvara, the corresponding author, is a lecturer and researcher at Great Zimbabwe University. Completed his Bachelor of Science in Biological Sciences and Statistics from the University of Zimbabwe, and completed his Masters of Science in Applied Microbiology and Biotechnology from National University of Science and Technology in Zimbabwe. Currently a PhD student at University of South Africa, working on antimalarial resistance and the efficacy of antimalarial plants against malaria.