Assessment of biofilm formation by Campylobacter spp.  strains mimicking slaughterhouse conditions

Patrícia Moedas Araújo

Key information

Authors:

Patrícia Moedas Araújo (Patrícia Moedas Araújo)

Supervisors:

Maria João dos Ramos Fraqueza; Ana Cristina Anjinho Madeira Viegas (Ana Cristina Anjinho Madeira Viegas)

Published in

03/23/2021

Abstract

The aim of this research was to evaluate biofilm formation of C. jejuni and C. coli strains isolated from poultry samples, taken at slaughterhouse level, in order to explain their survival and persistence through slaughter processing steps until the final consumer. Genotyping of an isolate collection (n=145) was performed by means of restriction fragment length polymorphism (RFLP) of the gene flaA. Pulse filed gel electrophoresis (PFGE) was also performed. Profiles were analysed with Bionumerics version 6.6., and by similarity and hierarchical clustering, 17 strains were selected for antimicrobial susceptibility tests and biofilm formation assays by crystal violet staining method. Biofilm assays were performed mimicking slaughterhouse environmental conditions, namely temperature, atmosphere, and contamination levels. Results obtained indicated that C. jejuni strains with similar flaA-RFLP profiles were present at slaughterhouse on different processing days. All strains tested were multidrug resistant, except one. Biofilm formation ability was strain dependent, and it was affected by inoculum concentration and tolerance to oxygen levels. The temperature of 10ºC negatively affected adherence levels. However, under microaerophilic and aerobic atmospheres at 42ºC, three strains: C. jejuni 46E, C. jejuni 61C and C. coli 65B, stood out exhibiting significant levels of biofilm formation. Strains formed aggregates (11 out of 17), and maintained viable cell counts after 72h of incubation at 10°C under aerobiosis. Most strains were considered weak biofilm producers by Stepanović et al. (2000) classification system. Other factors besides the ones studied could contribute to the permanence of some C. jejuni and C. coli strains at slaughterhouse.