From the Guidelines
Colistin resistance in India is a significant concern, with a prevalence rate ranging from 4-8% among clinical isolates, and it is crucial to address this issue through antimicrobial stewardship programs and surveillance. The geographical distribution of colistin resistance in India shows higher prevalence in urban centers like Delhi, Mumbai, Chennai, and Kolkata, particularly in tertiary care hospitals with extensive antibiotic use 1. Northern and southern regions of India generally report higher resistance rates compared to eastern and northeastern states. This resistance is primarily mediated by the mcr genes (especially mcr-1) and chromosomal mutations in the pmrAB and phoPQ regulatory systems.
- Key factors contributing to the emergence of colistin resistance include:
- Previous colistin exposure
- Prolonged hospitalization
- Immunocompromised patients
- Prior broad-spectrum antibiotic use
- The most common colistin-resistant pathogens in India are:
- Klebsiella pneumoniae
- Acinetobacter baumannii
- Pseudomonas aeruginosa To address the issue of colistin resistance, healthcare facilities should implement antimicrobial stewardship programs, conduct regular surveillance, use combination therapies when appropriate, and employ rapid diagnostic tests to detect resistance, as suggested by the task force on management and prevention of Acinetobacter baumannii infections in the ICU 1. The Indian government has taken steps to restrict colistin use in agriculture and veterinary settings, as food animals serve as important reservoirs for colistin-resistant bacteria and contribute to the spread of resistance genes. The use of colistin should be preserved for treating infections produced by A. baumannii strains showing resistance to all beta-lactams, fluoroquinolones, tigecycline, and a loading dose of 6–9 million IU and subsequently high, extended-interval maintenance doses should be used in critically ill patients 1.
From the Research
Epidemiology of Colistin Resistance in India
- There is limited information available on the epidemiology of colistin resistance in India, but a case report from 2 suggests that metallo-beta-lactamase (MBL)-producing Klebsiella pneumoniae may be present in the country.
- The study from 2 reported a case of a patient with sepsis from a urinary source due to carbapenemase-producing K. pneumoniae, which was sensitive only to colistin and tigecycline.
- The patient had a history of medical treatment in India, which suggests that MBL-producing K. pneumoniae may be present in the country.
Prevalence of Colistin Resistance in India
- There is no direct information available on the prevalence of colistin resistance in India from the provided studies.
- However, a review from 3 reported that colistin resistance rates are continually increasing in South-East Asia, which includes India.
- Another review from 4 reported that colistin-resistant bacteria have emerged in response to the unregulated use of this antibiotic, but did not provide specific information on the prevalence of colistin resistance in India.
Geographical Distribution of Colistin Resistance in India
- There is no information available on the geographical distribution of colistin resistance in India from the provided studies.
- However, a review from 5 reported that the mobile colistin resistance gene (mcr-1) was first discovered in E. coli from China in 2016, and has since been reported in various parts of the world, including Asia.
- Another review from 6 reported that colistin resistance has emerged as a significant global public health issue, but did not provide specific information on the geographical distribution of colistin resistance in India.
Mechanisms of Colistin Resistance
- The studies from 3, 4, and 6 reported that colistin resistance can occur through various mechanisms, including chromosomal mutations, acquisition of resistance genes carried by plasmids, and modification of lipid A.
- The study from 4 reported that the membrane modifications occur by the addition of cationic phosphoethanolamine (pEtN) or 4-amino-l-arabinose on lipid A, which results in a decrease in the negative charge on the bacterial surface.
- The study from 6 reported that different mechanisms of colistin resistance have been characterized, including intrinsic, mutational, and transferable mechanisms.