Molecular characterization of NDM-1-producing Pseudomonas aeruginosa isolates from hospitalized patients in Iran

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Genetics

Background:

• Carbapenem-resistant Pseudomonas aeruginosa (CRPA) poses a critical challenge in healthcare settings.
• The blaNDM-1 gene confers resistance to carbapenems, a last-resort antibiotic class.
• Understanding the genetic relatedness of CRPA is crucial for infection control.

Purpose of the Study:

• To perform double-locus sequence typing (DLST) on blaNDM-1 positive P. aeruginosa isolates.
• To characterize the genetic diversity and clonal relationships of these resistant strains.
• To investigate the co-occurrence of other carbapenemase and metallo-beta-lactamase (MBL) genes.

Main Methods:

• Collected 29 blaNDM-1 positive P. aeruginosa isolates from various Iranian cities over three years.
• Utilized Modified Hodge Test (MHT), Double-Disk Synergy Test (DDST), and Double-Disk Potentiation Test (DDPT) for carbapenemase and MBL detection.
• Employed Polymerase Chain Reaction (PCR) to identify specific antibiotic resistance genes and DLST for clonal analysis.

Main Results:

• All isolates exhibited resistance to imipenem and ertapenem.
• DDST and DDPT identified 51.8% and 89.7% of isolates as MBL producers, respectively.
• Detected blaOXA-10 (86.2%), blaVIM-2 (41.4%), blaIMP-1 (34.5%), and blaSPM (3.5%) genes; DLST identified a main cluster (DLST 25-11) involving 13 patients.

Conclusions:

• The co-existence of blaNDM-1 with other MBL genes in P. aeruginosa presents a significant therapeutic challenge.
• DLST analysis indicated partial genetic diversity among the studied blaNDM-1 positive P. aeruginosa isolates.
• These findings highlight the importance of molecular typing for tracking and controlling the spread of multidrug-resistant P. aeruginosa.