THE ROLE OF SANITATION IN THE DEVELOPMENT AND SPREAD OF ANTIMICROBIAL RESISTANCE

68 AMR CONTROL 2015 T he link between sanitation, or lack thereof, and antimicrobial resistance (AMR) is primarily to do with two factors: the level of antibiotic resistant bacteria in a person’s gut, and the level of AMR in the environment. The argument that resistance starts in a hospital and then spreads into the community or environment is often inaccurate and most certainly naïve. There is little evidence that few, if any, new antibiotic resistance mechanisms (ARMs) were acquired by bacteria in health settings yet there is some substantial evidence that clinically relevant bacteria have acquired ARMs from environmental bacteria typified by the sequestration of the CTM-X-15 gene by E. coli from environmental Kluyvera spp. and has now become the globally dominant extended spectrum β-lactamase (1–4). There is a significant documented problem of AMR occurring between animal, human and environmental sectors, including water bodies and soil (Fig. 1). Antibiotic resistant bacteria (and the antibiotics themselves) are excreted with effluents and sewage into the environment, and from there re-contaminate humans and animals via drinking water or food. This does not only concern antibiotic resistant bacteria but also antibiotics entering the ecosystem mediating direct resistance and collateral damage. Once antibiotics enter the ecosystems, they can influence bacterial populations (5), and correspondingly influence potable water (6, 7). Accordingly, critics have commented on the long-term impact of antibiotic remnants in aquatic and semi-aquatic environments (8–10). India produces about 40% of the world’s antibiotics and has been commended by WHO for supplying the world with miracle drugs but the contamination in the Indian (and generally throughout South Asia) environment with antibiotics is immense. Antibiotics can enter sewerage treatment plants (STPs) through human excretion, farm animals and the direct disposal of medical and industrial wastes. Some antibiotics are removed through the degradation and sorption to biosolids during treatment plant processes, such as the secondary and tertiary stages (11), but not all antibiotics are completely removed (12). Studies by Al-Ahmad et al. (2009) and Wiethan et al. (2000) suggest that bacteria, which have already shown resistance to antibiotics, will not necessarily have a selective advantage in sewage treatment (13, 14). Of greatest concern is the production and gross environmental contamination with fluoroquinolones (e.g. ciprofloxacin), once considered the perfect antibiotic. Studies have shown therapeutic levels of ciprofloxacin in Indian rivers and if the elegant studies of Beaber and colleagues are extrapolated to South Asia, this would indicate a colossal level of gene transfer happening in and between bacteria in this part of the world (15). This antibiotic load or pressure is further exacerbated by the levels of poorly degraded antibiotics contained in peoples normal flora that either enter sewerage treatment plants or worryingly, through open defecation. THE ROLE OF SANITATION IN THE DEVELOPMENT AND SPREAD OF ANTIMICROBIAL RESISTANCE