Chinese wastewater plants 'released drug immune gene'

Several wastewater treatment facilities may have discharged water into the environment that contains a gene called New Delhi metallo-β-lactamase resistance gene (NDM-1). This gene has been seen in a number of bacterial infections within people, which makes the bacteria immune to most β-lactam antibiotics. 

Concerns have now been raised over whether this discharge could result in more bacteria that are immune to antibiotics, which could have severe consequences on human and animal health.

Patients that are infected with bacteria that carry the NDM-1 gene have been seen in Australia, Europe, Asia and the US. The gene was first identified within a Swedish patient that was in an Indian hospital in 2008. It was found that the gene made the bacteria immune to the majority of antibiotics, even those that are only used as a last resort.

Research in 2010 performed by scientists from Rice University, US, found a large amount of the NDM-1 gene in the Haihe River in China. The discovery led them to examine a number of wastewater treatment facilities that were local to the river because this type of gene tends to be widespread in faecal matter. 

Bacterial DNA was extracted from the various stages of wastewater treatment at two different plants that were local to the Haihe River. Samples were also taken on the treated sludge, which is often used by farmers as a crop fertiliser. 

Polymerase chain reaction (PCR) was used to measure how much NDM-1 was present in each of the samples. It was found that there was an abundance of the gene in released wastewater from both of the facilities. The treated sludge was found to contain much higher concentrations of the gene. One of the plants released more concentrations of NDM-1 that was brought in via untreated wastewater. 

According to the researchers, the gene that was released by the wastewater treatment facilities is able to jump to other types of bacteria, resulting in them becoming immune to most forms of antibiotics.

Jeffrey Duchin, chair of the public health committee of the Infectious Diseases Society of America, told Chemical and Engineering News that the study "sounds a huge alarm" in terms of health. The more of these genes that are in the environment, he continued, the more chance there is for them to affect other types of bacteria.