Promoting One Health Efforts: The Ozonation of Persistent Antibiotics in Hospital Wastewaters (HWWs) and Its Contribution to the Development and Spread of Antibiotic Resistance in Low- and Middle-Income Countries

Abstract

Elevated bacterial resistance is extensively correlated with the increase in antibiotic usage, currently constituting a first-order public health problem as reported by the World Health Organization (WHO). Despite the WHO's global action plan to control the use of antimicrobial agents, the abuse of antibiotics persists [1,2]. It was noted that among 30.3% of patients consuming antibiotics, only 57.7% had approval from infectious disease specialists (IDS) [3]. This lack of oversight may contribute to the steadily increasing antibiotic consumption, which was approximately 42.3 billion defined daily doses (DDDs) in 2015 and is projected to rise to 128 billion DDDs by 2030 [4]. A growing concern is the residual antibiotics in hospital wastewater (HWW), one of the largest contributors to antibiotic contamination in aquatic environments [5]. More than 58% of consumed antibiotics are not metabolized and are excreted unchanged into the sewerage system [6]. These residual antibiotics, classified as micro-pollutants, have very low biodegradability and tend to be recalcitrant to various biochemical oxidizing agents [7]. Although the concentration of residual antibiotics in discharged HWW is typically low (nano to micrograms per liter) [8] [9], it increases the potential for resistance development [10,11]. The global burden of antibiotic resistance (AR) is exacerbated by these residual antibiotics [12]. LMICs are disproportionately affected due to inadequate healthcare infrastructure, over-the-counter sale of antibiotics, and poor sanitation [1]. These residual antibiotics enter the environment through pharmaceutical waste, agricultural runoff, and industrial discharges, creating environments that facilitate the selection and propagation of resistant bacteria by exerting selective pressure on microbial communities [13]. Ozone is a widely known chemical oxidizer, used since the 1990s to refine and disinfect drinking water [7]. Recently, it has been reported to degrade micro-pollutants, such as antibiotics, in various wastewater matrices [7,14]. Ozone decays in water, generating reactive oxygen species (ROS) and reactive nitrogen species (RNS), which have higher oxidative potency than ozone itself [7]. Ozonation, considered a promising advanced oxidation process (AOP), can cleave antibiotics into smaller, simpler pieces, depending on the dissolved ozone concentration in HWW [14]. However, the bio and ecotoxicity of antibiotic by-products can increase with higher ozone dosages, necessitating an optimal ozone dosage for maximum efficacy and minimal toxicity [15] ...