Veterinary Research Forum

Effects of agr genotype on biofilm-forming ability in Staphylococcus pseudintermedius isolates from broiler chickens

Document Type : Original Article

Authors

Sahar Nouri Gharajelar 1, 2
Pariya Heasri 3
Masoumeh Firouzamandi 1
Roghaiyeh Akbari 3

1 Department of Pathobiology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran

2 Department of Pathobiology and Veterinary Science, College of Agriculture, Health and Natural Resources, University of Connecticut, Storrs, USA

3 Master Student of Veterinary Bacteriology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran

10.30466/vrf.2025.2053976.4671
Abstract
The Accessory Gene Regulator (agr) operon as part of the quorum-sensing system, is responsible for regulating numerous virulence factors in Staphylococci. Furthermore, the ability of the opportunistic pathogen Staphylococcus pseudintermedius to form biofilm is a significant contributor to chronic diseases. Our aim was to evaluate of the association between different agr groups and the expression of the icaD gene related to biofilm formation among S. pseudintermedius isolates from nasal samples. Fifty nasal swabs were collected from broiler chickens and phenotypic and molecular tests were performed to isolate S. pseudintermedius from the samples and investigate their agr genotype. The biofilm production capacity of the isolates was determined using both a microtiter plate assay and amplification of the icaD gene. The S. pseudintermedius was detected in the 86.84% of samples. The assessment of agr typing results revealed that most of the strains (69.70%) were classified in agr group I. The relative frequency of biofilm producing S. pseudintermedius isolates was 75.76% and all of them harbored the icaD gene. The expression level of the icaD determinant was significantly higher among isolates in agr group I than other agr groups. These results suggest that broiler chickens may act as a reservoir for the transmission of S. pseudintermedius to humans which should be considered a potential zoonotic bacterium capable of producing different virulence factors like biofilms.

Keywords

agr group
Biofilm
Broiler chicken
icaD gene
Staphylococcus pseudintermedius
Subjects
Veterinary Research Forum
Volume 17, Issue 8
August 2026
Pages 573-579

  • Receive Date 20 February 2025
  • Revise Date 11 August 2025
  • Accept Date 15 November 2025

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