JMM Editor's Choice: Mutations causing antimicrobial resistance in Helicobacter pylori

Posted on April 3, 2019   by Microbiology Society

The Journal of Medical Microbiology (JMM) is a journal published by the Microbiology Society, focused on providing a comprehensive coverage of medical, dental and veterinary microbiology and infectious diseases, including bacteriology, virology, mycology and parasitology. This month, ​​​​Dr Arunaloke Chakrabarti, has selected an outstanding paper from the April issue to highlight as Editor’s Choice. The paper, titled 'Comparison of new and classical point mutations associated with clarithromycin resistance in Helicobacter pylori strains isolated from dyspeptic patients and their effects on phenotypic clarithromycin resistance' discusses the factors contributing to resistance in H. pylori.

H. pylori, the invariable colonizer of human gut, is associated with wide clinical spectrum ranging from asymptomatic gastritis to carcinoma. The standard eradication therapy involves lowering gastric acidity and eradicating H. pylori using antimicrobial agents. Unfortunately, the treatment success remains below 80%. This is largely due to the emerging resistance to clarithromycin, the agent forming the backbone of antimicrobial therapy.

This study describes the molecular characterization of clarithromycin resistance – conferring genes in 63 isolates of H. pylori collected in Turkey. After phenotypic screening of clarithromycin resistance, they studied the presence of  mutations that conferred classical (A2142G, A2142C and A2143G) and novel (A2115G, G2141A and A2144T) clarithromycin resistance. The novel mutations were present in considerable number (25-33%) of strains. 

This is the second study that has looked into the point mutations of clarithromycin-resistant H. pylori, beyond the classical codons. The study highlights the increasing relevance of novel mutations in clarithromycin resistance leading to treatment failure.

This study opens the door for future research – establishing correlation between detection of mutated gene and clinical failure of clarithromycin therapy, discovering other novel resistance-conferring mutations, and generating local epidemiological data on clarithromycin-resistant H. pylori.

Comparison of new and classical point mutations associated with clarithromycin resistance in Helicobacter pylori strains isolated from dyspeptic patients and their effects on phenotypic clarithromycin resistance

Helicobacter pylori is responsible for a wide variety of gastric diseases, with chronic infection leading to stomach ulcers and, in some people, cancer of the mucosal lining of the stomach. Typically, H. pylori  infection is cleared using a seven-day course of the antibiotic clarithromycin. H. pylori is rapidly devloping resistance to these antimicrobials, and the success rate for H. pylori treatment has now fallen to below 80%. 

The research assessed the mechanisms of resistance to clarithromycin in H. pylori collected from 63 patients in Turkey. 23 (36.5%) of these isoaltes were found to be resistant to clarithromycin. Using real-time PCR, six point mutations were identified. Understanding the relevance of point-mutations in antimicrobial resistance is important in recognising how these bacteria develop resistance and how new antimicrobial strategies can be identified.