A novel functional class 2 integron in clinical Proteus mirabilis isolates.

Area of Science:

• Microbiology
• Genetics
• Antimicrobial Resistance

Background:

• Integrons are genetic platforms that capture and express gene cassettes, contributing to antimicrobial resistance.
• Class 1 and Class 2 integrons are commonly found in clinical bacteria, including Proteus species.
• Understanding integron diversity is crucial for tracking the spread of antibiotic resistance genes.

Purpose of the Study:

• To identify and characterize novel integron structures in clinical isolates of Proteus mirabilis.
• To investigate the prevalence and genetic relatedness of Proteus mirabilis isolates carrying class 2 integrons.

Main Methods:

• Screening of 153 clinical Proteus isolates for class 1 and class 2 integrons using PCR.
• Determination of integron variable regions via restriction analysis and sequencing.
• Phylogenetic analysis of integron-positive isolates using Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR.

Main Results:

• Class 1 integrons were found in 63% of isolates, with eight gene cassette arrays identified, including a novel array in P. mirabilis.
• Class 2 integrons were detected in 66% of isolates, with four arrays found, including a novel array in a class 2 integron.
• A novel functional class 2 integron, containing dfrA14 and three novel open reading frames, was identified in 38 P. mirabilis isolates with similar ERIC-PCR patterns, suggesting clonal spread.

Conclusions:

• A novel functional class 2 integron was identified for the first time in Proteus mirabilis.
• The identified Proteus mirabilis isolates harboring this novel class 2 integron appear to be clonally disseminated within the hospital environment.