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Diverse Genetic Array of blaCTXM-15 in Escherichia coli: A Single-Center Study from India
Anand Prakash Maurya1, Shweta Mishra2, Anupam Das Talukdar3
11 Department of Microbiology, Assam University , Silchar, India .
Abstract:
CTX-M-15 is a chief contributor for expanded-spectrum cephalosporin and monobactam resistance in India, complicating treatment options. In this study, we have investigated genetic context of CTX-M-15 in Escherichia coli and their transmission dynamics in a tertiary referral hospital of India. A total of 198 isolates were collected, of which 66 were harboring blaCTXM-15. Among them, 14 isolates were carrying a single CTX-M-15 gene and 52 were harboring multiple extended-spectrum β-lactamase genes along with blaCTX-M-15. The resistance gene was flanked by tnpA, ISEcp1, IS26, and ORF477 in 10 different arrangements. The resistance determinant was horizontally transferable through F, W, I1, and P Inc types of plasmids. Restriction mapping of plasmids showed a variable band pattern even within the same Inc types. Minimum inhibitory concentration was found above the breakpoint level against expanded-spectrum cephalosporins and monobactam while susceptible against carbapenems. blaCTX-M-15 was highly stable and sustained in the cell after 115 serial passages. In pulse-field gel electrophoresis, eight pulsotypes of E. coli were found to be responsible for the spread of blaCTX-M-15 in the tertiary referral center. We conclude that the presence of CTX-M-15 in the heterogeneous group of E. coli is highly alarming in terms of infection control and it may require regular monitoring, so as to formulate appropriate antibiotic policy to stop the spread of this resistance determinant.
Insights
CTX-M-15 is a significant cause of resistance to extended-spectrum cephalosporins and monobactams in India. This study reveals its genetic context and transmission in Escherichia coli within a major hospital, highlighting infection control challenges.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- CTX-M-15 is a primary driver of resistance to extended-spectrum cephalosporins and monobactams.
- This resistance poses a significant challenge to effective antibiotic treatment in India.
Purpose of the Study:
- To investigate the genetic context of the blaCTX-M-15 gene in Escherichia coli.
- To understand the transmission dynamics of CTX-M-15 producing E. coli in a tertiary care hospital.
Main Methods:
- Analyzed 198 E. coli isolates, with 66 harboring blaCTX-M-15.
- Investigated flanking genetic elements, plasmid-mediated horizontal transfer, and E. coli genetic diversity using pulse-field gel electrophoresis.
- Determined minimum inhibitory concentrations and assessed gene stability through serial passages.
Main Results:
- The blaCTX-M-15 gene was found in various genetic arrangements and was horizontally transferable via multiple plasmid types.
- E. coli isolates exhibited high-level resistance to expanded-spectrum cephalosporins and monobactams but remained susceptible to carbapenems.
- Eight distinct E. coli pulsotypes were identified as vehicles for blaCTX-M-15 spread within the hospital.
Conclusions:
- The widespread presence of CTX-M-15 in diverse E. coli strains is a serious concern for infection control.
- Regular monitoring and strategic antibiotic policies are crucial to curb the dissemination of this resistance determinant.
