75 CBNAAT TB-testing machines idle in Karnataka as cartridges run out

As many as 75 CBNAAT (Cartridge Based Nucleic Acid Amplification Test) machines (each costing at least Rs 13 lakh) used to test tuberculosis (TB) are idling in the state for want of test cartridges.

Ever since the Central TB Division (CTD) decentralised the procurement of these cartridges, the state has been able to source very few cartridges through local purchase with the amount sanctioned.

In the first quarter of the current financial year, 67,680 sputum smear microscopy examinations were done. If the sputum has less than 5,000 bacilli/ml, smear microscopy is highly unlikely to diagnose pulmonary TB. Thus it has an overall low sensitivity.

In comparison, CBNAAT needs only 150 bacilli per ml of clinical specimen to be positive. There are 2,900 TB patients in the state. Limited stocks of cartridges of around 50-200 are being reserved for emergency cases like HIV-TB, ICU patients and paediatric age groups, in seven districts of the state: Chikkaballapur, Belagavi, Bagalkot, Bangalore Rural, BBMP, Tumakuru and Bangalore Urban.

In Bengaluru, the state has a stock of the last five cartridges. In all other districts, cartridges have stocked out.

"We used to have perennial supply of CBNAAT cartridges. In the past, we didn't face a shortage a single day. Now a tender is being called in Belagavi (which is left with 100 cartridges) for Rs 50 lakh to procure 3,000 cartridges. We could test 22,000 samples in a month in the past. These many patients can benefit with early diagnosis and better treatment outcomes every month if these machines are up and running," said a source.

"Considering that we tested a whopping 67,680 samples with sputum microscopy, we can't rely on Truenat machines alone to shoulder the load, which can test only four to six samples a day in three cycles. In August, we did 20,000 Truenat tests. Considering we are a high-burden TB state which did 10 lakh sputum examinations in 2019 alone, we need to deploy all testing tools and cannot afford to have them gathering dust," he said.

Despite having 100 Truenat machines, which is a point-of-care test, having CBNAAT cartridges will help the state do 22,000 additional tests in a month.

Dr Ramesh Reddy, Joint Director, TB, said, "At present, we don’t have stock of CBNAAT cartridges. This used to be supplied by CTD. They have decentralised the process and asked us to them procure locally. We have called for tender with the amount sanctioned to us. We have also sought additional funds from the Centre to procure adequate quantity."

Reddy said the state had 62,600 Truenat MTB chips and 16,300 Truenat RIF chips.