The Effect of Antimicrobial Resistance Plasmids Carrying blaCMY-2 on Biofilm Formation by Escherichia coli from the Broiler Production Chain.

Live L Nesse,Ingun L Witsø,Lene K Vestby,Solveig S Mo,Silje N Ramstad,Camilla Sekse,Anna Eline E Bruvoll,Anne Margrete Urdahl

doi:10.3390/microorganisms9010104

Abstract

Extended-spectrum cephalosporin-resistant Escherichia coli (ESCR E. coli) with plasmids carrying the blaCMY-2 resistance gene have been isolated from the Norwegian broiler production chain through the Norwegian monitoring program for antimicrobial resistance in animals, food and feed, NORM-VET. The aim of the present study was to investigate the biofilm forming abilities of these strains, and in particular to see whether these might be influenced by the carriage of blaCMY-2 plasmids. The ESCR E. coli from the broiler production chain displayed relatively low biofilm forming abilities in the crystal violet biofilm assay as compared to quinolone-resistant E. coli (QREC) from the same population (mean ± SD = 0.686 ± 0.686 vs. 1.439 ± 0.933, respectively). Acquisition of two different blaCMY-2 plasmids by QREC strains reduced their biofilm production in microtiter plates, but not their biofilm production on Congo Red agar plates. Furthermore, motility was reduced, but not planktonic growth. We hypothesize that genes carried by these plasmids may have caused the observed reduction in biofilm formation, possibly mediated through changes in flagellar expression or function. Furthermore, this may help explain the different biofilm forming abilities observed between ESCR E. coli and QREC. The results also indicate that the risk of biofilm reservoirs of antimicrobial resistant E. coli on in the broiler production is lower for ESCR E. coli than for QREC.

Highlights

In broiler chickens, extended-spectrum cephalosporin-resistant Escherichia coli (ESCRE. coli) were first described two decades ago [1] and are shown to be globally distributed [2].This is an increasing cause of concern, as cephalosporins have been listed by the WHO as critically important antimicrobials in human medicine [3].In Norwegian broilers, ESCR E. coli was detected in 2006 [4]
Biofilm Production by ESCR E. coli Related to Biofilm Assay and Morphotype
Biofilm formation by the ESCR E. coli strains was measured both on the organic surface on CR agar plates and on the inert surface of microtiter plates

Summary

Introduction

In broiler chickens, extended-spectrum cephalosporin-resistant Escherichia coli (ESCRE. coli) were first described two decades ago [1] and are shown to be globally distributed [2].This is an increasing cause of concern, as cephalosporins (third, fourth and fifth generation) have been listed by the WHO as critically important antimicrobials in human medicine [3].In Norwegian broilers, ESCR E. coli was detected in 2006 [4]. E. coli) were first described two decades ago [1] and are shown to be globally distributed [2]. This is an increasing cause of concern, as cephalosporins (third, fourth and fifth generation) have been listed by the WHO as critically important antimicrobials in human medicine [3]. The E. coli strains carrying these plasmids may not be pathogenic, there is a large potential of dissemination of the resistance genes to pathogens through horizontal transfer of the plasmids. Most isolates carry a blaCMY resistance gene, mainly encoded by plasmids belonging to two of the major resistance plasmid families identified in clinically relevant Enterobacteriaceae—i.e., IncK and IncI. There may be genes encoding other proteins as well as hypothetical proteins [7]

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