Proteae: a reservoir of class 2 integrons?

Area of Science:

• Microbiology
• Genetics
• Antimicrobial Resistance

Background:

• Integrons are mobile genetic elements that play a crucial role in the dissemination of antibiotic resistance genes.
• Class 2 integrons, characterized by the intI2 gene, are frequently found in various bacterial species.

Purpose of the Study:

• To confirm the high prevalence of class 2 integrons in clinical isolates of the Proteae tribe (Proteus, Morganella, and Providencia spp.).
• To analyze the genetic characteristics and diversity of gene cassette arrays associated with class 2 integrons in Proteae.

Main Methods:

• Quantitative PCR was used to detect class 1, 2, and 3 integrons in 327 clinical Proteae isolates.
• Sanger sequencing and PCR-RFLP were employed to determine the intI2 gene status and characterize gene cassette arrays.
• Next-generation sequencing was utilized when necessary for complex array analysis.

Main Results:

• Class 2 integrons were detected in 31.5% (103/327) of Proteae isolates, while class 1 integrons were found in 13.8% (45/327).
• Six distinct gene cassette arrays were identified, including four previously described and two novel arrays, one associated with a functional IntI2 integrase and a new gene cassette (gcu115).

Conclusions:

• Proteae bacteria exhibit a high frequency of class 2 integrons, indicating their significant role as a reservoir for these elements.
• The diversity of gene cassette arrays found in Proteae highlights their potential contribution to the spread of antimicrobial resistance genes.