NDM1 and antimicrobial resistance: Need for objective introspection

The recent controversy around NDM-1 has again brought to the fore the deep rooted malaise of Indian health system – scientific leadership responding to public health events based on judgement instead of evidence. And therefore it is not surprising that the response and risk communication following publication of NDM-1 reports in the Lancet were completely lopsided. The issue of drug resistance and the systemic factors responsible for it in India were completely side-tracked by the rhetoric and counter allegations of hidden agenda of foreign medical community to malign India’s growing medical prowess and lucrative medical tourism. While one does understand the sentiment of such reports having the potentially negative economic impact in a globalized world and the need to have more systematic nomenclature for bacterial resistance genes, one also expected a more calibrated and scientific response to these reports.

The recent study on NDM-1 bacilli in Delhi water supply was a follow up to an earlier report on presence of NDM-1 positive bacteria in patients returning from India to European countries. The study was designed to look for NDM-1 positive resistant bacteria in the environment and was not designed to establish any clinical or epidemiological correlation. Therefore, the absence of these correlations doesn’t qualify as an argument against its finding, namely, environment circulation of NDM-1 β-lactamase-producing bacteria in different areas of New Delhi. However, less focus on other resistanace bacteria possibly artificially inflated NDM-1. Same applies to seepage and tap water samples used in the study as well. E.g. All seepage samples grew bacteria (including Enterobacteriaceae) that were resistant to cefotaxime, and 166 of 171 grew bacteria on media containing 0•5 mg/L meropenem. All the concentrated water samples grew bacteria on media containing cefotaxime and 14 of 50 grew on media containing meropenem”.

The rebuttal on presence of NDM-1 positive bacteria in drinking water samples in Delhi was equally non-scientific. It’s no rocket science that, even with adequate chlorination upstream, various practices at the end user level can result in contamination of tap water. Therefore, a number of tap water samples are likely to be unfit for drinking in the normal course (due to various factors such as decay in chlorine levels, illegal use of booster pumps to draw water from water lines thus damaging the supply system etc.), which is quite often the case and could possibly be said to be a greater public health threat for the local population in terms of disease burden than presence or absence of NDM-1 positive bacteria. What also needed to be communicated to the general public was that occurrence of disease both in case of Vibrio cholera and Shigella depends on factors such as adequate Infective Dose, presence of all the genetic elements to trigger the pathogenesis etc. Therefore, presence of these bacteria by itself should not cause panic.

From drug resistance point of view the threat is real, especially in view of the fact that some of the known pathogens such as Vibrio cholera and Shigella boydii have been shown to possess the resistance gene. The gene is also transferable to known pathogenic bacteria. Once infected with these or other NDM-1 positive bacteria, treatment is very difficult and therefore it does constitute a public health threat.

The discussions following the publication of both papers in internationally reputed journals raise important questions about the quality of public health discourse in India. Some Indian experts suggested that the study findings would be acceptable only if comparative studies are performed in other cities of India, US and Europe. Is this a reason enough to doubt the findings of this study and does it really change the actual problem of antimicrobial resistance?  The public health community in India should seriously consider if such suggestions will serve only to divert attention from the real issue which is the presence of multi drug resistant bacteria including NDM-1? Lastly, in spite of all these questions doubting the technical veracity of the quoted studies, will it be correct to say that the problem of NDM-1 is not a public health threat?

Development of resistance in bacteria in the environment including multi drug resistance is a dynamic process that is virtually impossible to arrest. We could contribute less to it by more rational use of antimicrobials. The risk of acquiring NDM-1 from the environment is no different from risk due to other resistant bacteria unless it can be associated with certain specific environments. However, presence of NDM-1 positive bacteria is indicative of the evolution of bacteria into more resistant strains. This, in turn, is a reflection of the antimicrobial use practices in the larger clinical practice. This, in itself, continues to be a significant public health risk which cannot be ignored.


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