What are the microbes in the river in Ethiopia? Why is there strong drug resistance? The reason?
The spread of drug-resistant pathogens is a global health problem. Most studies reported high levels of antimicrobial resistance genes (ARGs) in aquatic environments; However, the levels associated with sediment are limited. This study aims to investigate the distribution of ARGs in sediment and water in the Akaki River in Addis Ababa, Ethiopia. Sediment and water collected from five sites on the Akagi River assessed the diversity and abundance of 84 ARGs and 116 clinically important bacteria.
Most ARGs are found in cities close to human activity. Water samples collected in the central river catchment contained 71-75% of the target ARG, and genes encoding aminoglycoside acetyltransferase (aac(6)-IB-cr), aminoglycoside adenosyltransferase (aadA1), β-lactamase (bla OXA-10), quinolone-resistant S (qnrS), macrolide efflux protein A (mefA), and tetracycline-resistant (tetA) were detected at all sampling points.
Much less ARG was detected in all sediments, and sediments near hospitals had the highest diversity and levels. Despite lower levels and diversity, no unique ARGs were detected in sediments and not detected in waters. Multiple clinically relevant pathogens have also been detected in the Akaki River. The findings suggest that the aqueous phase, rather than sediment in the Akagi River, is a potential conduit for the spread of ARG and antibiotic-resistant bacteria.
Decades of widespread use of antibiotics to treat human and animal infections, as well as as food supplements for livestock, have led to the rapid emergence of drug-resistant bacteria (ARBs). Infectious diseases caused by ARBs are once again a major global public health problem, resulting in fewer treatment options for some infections. As a result, morbidity and mortality from infections caused by ARBs are the greatest healthcare crisis of the twenty-first century. According to the European Centre for Disease Prevention and Control, around 33,000 people die each year in Europe and the European Economic Area from infections caused by ARB.
In sub-Saharan Africa, the management of drug-resistant infections has become more difficult due to a lack of diagnostic facilities and inadequate surveillance systems. To control the spread of ARB, studies have focused mainly on isolates in clinical settings, with little attention paid to environmental transmission. However, the environment outside of healthcare facilities plays an important role in the spread of ARBs. Antimicrobial resistance cannot be solved by simply managing problems in healthcare settings; Therefore, it must be confronted from the perspective of One Health, which crosses human, veterinary and environmental boundaries.
Antibiotic-resistant pathogens persist in the environment due to the continuous excretion of fecal bacteria and antibiotic residues. Most antibiotics are excreted in their active form, and although some antibiotics have a short half-life, less than a day (e.g., amoxicillin), sustained excretion in the environment depending on conditions results in pseudopersistent selection of subinhibitory concentrations of ARBs.
However, some antibiotics, such as tetracyclines and macrolides, have much longer half-lives in water and even longer in sediments. This is relevant because sediments in aquatic systems are considered important reservoirs of antimicrobial resistance genes (ARGs) and facilitate the spread of antimicrobial resistance pathogens in the environment. ARGs associated with aquatic sediments are considered persistent and therefore may be continuously released into the relevant waters. Therefore, understanding the diversity of ARGs in sediments and aqueous phases is important for sustainable antimicrobial resistance control.
The negative impact of human activities on the aquatic environment is a concern about the continued spread of antimicrobial-resistant pathogens. Bacteria can acquire antibiotic resistance through mutation and horizontal gene transfer, which not only contributes to the abundance and diversity of resistance genes in the aquatic environment, but also distributes them across different bacteria. However, a major source of ARB in aquatic environments is untreated sewage discharge from healthcare facilities and homes.
Most of these studies use culture-based methods that typically involve isolating the bacteria of interest on general or selective media and then evaluating the ARG. Assessing antibiotic resistance in cultureable bacteria in the environment provides only partial information and misses the detection of ARGs in culturable bacteria.
Conclusion:
ARGs levels in sediments are consistently lower than in water. Lactamase-coding genes are less diverse and abundant in sediments, while aminoglycoside and fluoroquinolone resistance genes are more abundant. The aqueous facies of the city-influenced aquatic environment, rather than associated sediments, may be the main source of ARGs and ARBs that persist and spread in the Akaki River. ARGs have the highest levels in urban locations affected by a range of human activities, including agriculture, hospitals, industry, and densely populated residential areas that release untreated waste and contribute to the diversity and richness of ARGs.
As a result, rivers become reservoirs of major clinically relevant ARGs that can be transmitted between environmental and pathogenic bacteria in rivers and subsequently to residents, posing a public health risk. To effectively implement an antimicrobial stewardship program, the role of the environment in the generation and spread of ARGs must also be considered. This study highlights the importance of considering the aquatic environment in Ethiopia's antimicrobial resistance surveillance system to effectively control the spread of drug-resistant bacteria and resistant genes.
Rivers become reservoirs for the main clinically relevant ARGs, which can be transmitted between environmental and pathogenic bacteria in rivers and subsequently to residents, posing a public health risk. To effectively implement an antimicrobial stewardship program, the role of the environment in the generation and spread of ARGs must also be considered. This study highlights the importance of considering the aquatic environment in Ethiopia's antimicrobial resistance surveillance system to effectively control the spread of drug-resistant bacteria and resistant genes.
