Speedy test for antibiotic resistance

An international research team, including KAIMRC’s Hosam Zowawi, has assessed the early ‘beta’ version of a test for antibiotic-resistant bacteria; the ‘SpeeDx Carba (beta) multiplex real-time PCR assay.’ The test is based on detecting key genes responsible for antibiotic resistance. 

Zowawi contributed to the study’s conception and design, and the samples tested came from seven countries, including Saudi Arabia.

The targeted bacteria produce enzymes called carbapenemases, which can break down some of the most common antibiotics, including penicillins, cephalosporins, monobactams, and carbapenems.

The authors point out that carbapenemase-producing organisms (CPOs) are of global concern. The World Health Organisation identifies several CPOs as being at risk of becoming untreatable.

A key aspect of combatting the CPO threat will be to develop more sensitive and simpler methods to detect them in saliva, blood and faeces, as well as in the environment.

The SpeeDx test uses the technique called polymerase chain reaction (PCR), which employs a combination of a DNA copying enzyme (the polymerase) and DNA fragments called primers that match parts of the genes of interest. The primers combine with the bacterial DNA, initiating multiplication by the polymerase enzyme to make readily detectable levels. The team focused on identifying five types of gene that code for the carbapenemase enzymes of some of the most troublesome antibiotic-resistant bacteria. 

In trials using bacterial samples whose identity is known, the test positively identified the carbapenemase genes in 152 of 154 samples. It also successfully yielded negative results for all samples lacking the target genes. The test also gave promising results when used directly on faecal samples.

“The initial results from the direct faecal sample testing suggest the Carba (beta) assay may be suitable for screening purposes, but more work is needed,” the authors conclude. This further development will include testing the procedure on a variety of different clinical and environmental samples. 

“We are pleased with the performance of the test in this evaluation,” says Elisa Mokany, SpeeDx chief technology officer and founder of SpeeDx, the Australian biotech company developing the test.

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