News Excerpt:

Researchers from the National Institute of Cholera and Enteric Diseases (ICMR-NICED), Kolkata, have developed a two-step PCR test of the Helicobacter pylori (H. pylori) bacteria. It can help detect H. pylori infection and also identify clarithromycin-resistant bacteria and those that are drug-sensitive in six to seven hours.

Helicobacter pylori (H. pylori) infection:

• It occurs when Helicobacter pylori (H. pylori) bacteria infect the stomach.

• It is the most common cause of peptic ulcers, which are painful open sores in the digestive tract. In rare cases, it could even lead to stomach cancer.
• About two-thirds of the world’s population has it in their bodies. For most people, it never causes any symptoms.
• In India, H. pylori infection affects 60-70% of the population. 
• This usually happens during childhood and remains in the stomach throughout their life if not treated with antibiotics effectively.

• Symptoms:

• An ache or burning pain in your stomach (abdomen)
• Stomach pain that may be worse when your stomach is empty
• Nausea
• Loss of appetite
• Frequent burping
• Bloating
• Unintentional weight loss

Why is it a concern?

• As it takes three weeks to culture the bacteria and carry out drug-sensitivity tests. So, the conventionally used empirical treatment using clarithromycin is routinely used without knowing the drug's sensitivity. 
• The growing incidence of clarithromycin-resistant bacteria is a big concern and has to be addressed as it is the most important reason for treatment failure.

Highlights of the study:

• The researchers used Genome Sequencing to pin- point the problems.
• They identified that the drug resistance was due to a point mutation (A to G mutation at 2143 position) in the 23S ribosomal RNA (rRNA) gene of the bacteria.
• The study revealed that drug-resistant and drug-sensitive strains had very different binding affinity for the drug. 
• The drug’s binding affinity to the mutant one was weaker than its affinity to the drug-sensitive one.
• Due to weak binding, less amount of the drug can get into the bacteria, and so it is unable to kill them. The point mutation is thus responsible for the clarithromycin resistance.
• The new molecular-based assay has been found to have 100% sensitivity and specificity, thus creating a milestone in this journey.