Class 1 integron causes vulnerability to formaldehyde in Escherichia coli

Area of Science:

• Microbiology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Escherichia coli (E. coli) are significant pathogens in poultry.
• Integrons are genetic elements known to confer resistance to antimicrobials and disinfectants.
• Formaldehyde is a common disinfectant with potential to induce resistance.

Purpose of the Study:

• To investigate the relationship between integron 1, formaldehyde dehydrogenase, and orfF genes and formaldehyde resistance in E. coli.
• To determine the prevalence of these genetic markers in E. coli isolated from broilers.
• To explore the potential role of integron 1 in modulating formaldehyde sensitivity.

Main Methods:

• Isolation of E. coli from healthy and diseased broilers.
• Determination of formaldehyde resistance levels using Minimum Inhibitory Concentration (MIC) tests.
• Detection of integron 1, formaldehyde dehydrogenase, and orfF genes using Polymerase Chain Reaction (PCR).

Main Results:

• Prevalence rates were 61% for integron 1, 8% for orfF, and 94% for formaldehyde dehydrogenase.
• 15% of E. coli isolates exhibited formaldehyde resistance, while 85% were sensitive.
• Isolates carrying integron 1 showed significantly higher sensitivity to formaldehyde, contradicting expectations.

Conclusions:

• Integron 1 may enhance bacterial surface protein expression, leading to increased formaldehyde sensitivity.
• This study reports the first instance of integron 1 inducing sensitivity to a disinfectant.
• Integron 1 can represent a vulnerability rather than an advantage for E. coli against formaldehyde.