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Detection of vim- and ipm-type metallo-beta-lactamases in Pseudomonas aeruginosa clinical isolates
Saeed Sepehriseresht1, Mohammad Ali Boroumand, Leila Pourgholi
1Molecular Pathology Department, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
Background:
Pseudomonas aeruginosa is the most important bacterium isolated from burn wounds, and its resistance to imipenem due to metallo-beta-lactamases is increasing. This study was designed to detect vim1, vim2, ipm1 and ipm2 metallo-beta-lactamases genes between Pseudomonas aeruginosa isolates isolated from Shahid Motahari Burns Hospital, Iran.
Methods:
To that end, we isolated 483 nonduplicate consecutive isolates of P. aeruginosa from burn infections; and after biochemical confirmation, we examined the imipenem susceptibility via the Kirby-Bauer method. All the imipenem-resistant and imipenem-intermediate isolates were screened for vim1, vim2, ipm1 and ipm2 genes through the PCR method.
Results:
From the 483 isolates, 272 (56%) and 63 (13%) isolates had resistant and intermediate zones in their imipenem antibiogram pattern, respectively. Fifty-four (16.1%), 7 (2.1%), 22 (6.6%), and 11 (3.3%) of the resistant and intermediate isolates had vim1, vim2, ipm1 and ipm2 genes in their PCR results, respectively.
Conclusion:
MBL-mediated imipenem resistance in P. aeruginosa is a cause for concern in the treatment of infective burn patients. The rate of imipenem resistance due to MBL was increased dramatically and newer versions of MBL families were detected for the first time. These results suggest that an effective method should be provided to fight MBL production in clinical isolates.
Insights
Metallo-beta-lactamase (MBL) genes, including newer variants, are increasingly detected in Pseudomonas aeruginosa from burn wounds, contributing to rising imipenem resistance. This necessitates urgent strategies to combat MBL production in clinical settings.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Pseudomonas aeruginosa is a primary cause of burn wound infections.
- Increasing metallo-beta-lactamase (MBL) mediated resistance to imipenem poses a significant treatment challenge.
- This study focuses on Iranian burn wound isolates.
Purpose of the Study:
- To detect specific MBL genes (vim1, vim2, ipm1, ipm2) in Pseudomonas aeruginosa.
- To investigate the prevalence of these genes in imipenem-resistant and intermediate isolates.
- To assess the contribution of MBLs to imipenem resistance in burn wound infections.
Main Methods:
- Isolation and biochemical confirmation of 483 P. aeruginosa strains from burn infections.
- Determination of imipenem susceptibility using the Kirby-Bauer method.
- Screening for MBL genes (vim1, vim2, ipm1, ipm2) via Polymerase Chain Reaction (PCR) in resistant/intermediate isolates.
Main Results:
- High rates of imipenem resistance (56%) and intermediate susceptibility (13%) were observed.
- MBL genes were detected in a significant proportion of resistant/intermediate isolates: vim1 (16.1%), vim2 (2.1%), ipm1 (6.6%), and ipm2 (3.3%).
- Newer MBL variants were identified, indicating evolving resistance mechanisms.
Conclusions:
- MBL-mediated imipenem resistance in P. aeruginosa is a growing concern for burn patient treatment.
- The detection of novel MBL families highlights the increasing prevalence of these resistance genes.
- Effective interventions are crucial to control MBL production in clinical P. aeruginosa isolates.
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