2023 Tamil Nadu outbreak of neurological infection traced to contaminated saline at clinic: Study

New Delhi: A genetic study has traced a 2023 outbreak of a neurological infection in Tamil Nadu to contaminated saline water used at a dental clinic, findings of which were published in The Lancet Regional Health Southeast Asia journal.

Twenty-one probable cases of neuromelioidosis -- a neurological infection caused by bacterium Burkholderia pseudomallei -- between July 2022 and April 2023 were identified across four districts in the northern part of the state.

Seventeen of the 21 cases came from a single district, of which 10 reported undertaking treatment at a dental clinic. The cluster of cases were found to have higher and quicker deaths, compared to the other 11 sporadic cases from environmental sources.

Researchers from Christian Medical College, Vellore, Indian Council of Medical Research-National Institute of Epidemiology, Chennai, and other institutes attributed the cluster to invasive dental procedures -- injecting of a local anaesthetic and repeated irrigation with saline -- performed under suboptimal infection prevention and control conditions.

Whole genome sequencing of 209 isolates, obtained from tissue, blood, and cerebrospinal fluid samples of the affected, revealed 'ST1553' strain of the bacterium B pseudomallei as being associated with the neurological infection outbreak.

Along with suggesting a new process by which neuromelioidosis can be contracted, the findings highlighted the importance of molecular (genetic) methods of analysis in identifying the strain of the bacterium circulating in southeast Asia.

Rigorous infection prevention and control practices across healthcare facilities, particularly those performing invasive procedures, need to be enforced, the authors said.

"We confirmed a large cluster of neuromelioidosis from south India, likely representing sporadic cases from environmental sources and cases linked to an iatrogenic source (complication resulting from treatment) at a dental clinic," the authors wrote.

"Rapid and high case fatality among dental cases supports the direct trans-neural spread of B pseudomallei to the brainstem following inoculation via contaminated saline," they wrote.