Characteristics of virulence, resistance and genetic diversity of strains of Salmonella Infantis isolated from broiler chicken in Brazil

Abstract

Salmonella Infantis is frequently associated with human infections worldwide and is transmitted by consumption of contaminated foods, particularly those of animal origin, especially the chicken meat. We aimed to evaluate virulence characteristics, antimicrobial resistance and the genetic similarity of 51 strains of S. Infantis isolated from samples of poultry origin. The strains were isolated from 2009 to 2010 in a company with full cycle of broiler’s production in the state of São Paulo, Brazil. The antimicrobial susceptibility test was performed and, by PCR, we evaluated the presence of the genes lpfA (hem-adhesion), agfA (hem-biofilm) and sefA (hem-adhesion) and resistance genes to beta-lactams (blaTEM, blaSHV, bla CTX-M and blaAmpC ). The phylogenetic relationship was determined by RAPD-PCR method. Among the drugs tested, the highest percentages of resistance were to amoxicillin (35.3%) and to sulfonamide (15.7%). Eleven antimicrobial resistance patterns were identified (A1 to A11), none of them presented a multiresistance profile (> 3 antimicrobials classes). There was 100% of positivity for the agfA gene, 92.2% for the lpfA gene, and no strain presented the sefA gene. Most of the isolates showed similarities in virulence potential, since they were simultaneously positive for two studied genes, agfA and lpfA (92.2%, 47/51). Of the 18 (35.3%) strains resistant to antimicrobials of the β-lactam class, 10 (55.5%) were positive to blaAmpC gene, five (27.8%) for blaCTX-M , two (11.1%) to blaSHV and no strain presented the blaTEM gene. The phylogenetic evaluation has shown the presence of five clusters (A, B, C, D and E) with similarity greater than 80%, and three distinct strains which were not grouped in any cluster. Cluster B grouped 33 strains, all positive for lpfA and agfA genes, from both, the broiler farming facility and the slaughterhouse, persistent throughout all the study period. This cluster also grouped 18 strains clones with genetic similarity greater than 99%, all isolated in the slaughterhouse. The presence of virulence genes associated with persistent strains clones for a long period, warns to the possibility of S. Infantis to form biofilm, and should be constantly monitored in broilers’ production chain, in order to know the profile of the strains that may contaminate the final product and evaluate the hazards that represents to public health.

Molecular Characterization of Salmonella Detected along the Broiler Production Chain in Trinidad and Tobago

“…Worldwide, the rapid development of resistance to extended-spectrum cephalosporins, predominantly associated with the production of β-lactamase-producing bacteria (EsβL) in different Salmonella serovars, has been reported. In agreement with our study, EsβL resistance genes have been detected in Salmonella strains isolated from animal products in several countries, including Korea (food animals and humans), 1.6% [ 45 ], Mexico (humans and animals), 6.6% [ 46 ], and Brazil (broiler chickens), where 27.8% [ 47 ] of isolates were positive for the bla CTX-M gene. The detection of 6.8% MDR strains among serovar Infantis isolates possessing the bla CTX-M-65 gene is of public health significance due to the reported cross-transmission of EsβL-producing bacterial strains from poultry farms to other livestock farms and humans with the potential for wide-spread population infections [ 48 , 49 ].…”

Molecular Characterization and Survive Abilities of Salmonella Heidelberg Strains of Poultry Origin in Brazil

“…It is restricted to group D serovars, Enteritidis, Dublin, Moscow, and Blegdon serotypes (Amini et al, 2010). Thus, the absence of this gene in SH was expected, but its presence was investigated due to the possibility of genetic recombination, which can occur when the sefABCD genes present G + C around 35.2%, suggesting horizontal transfer (Bäumler et al, 1997;Mendonça et al, 2020).…”

Characterization of a pESI-like plasmid and analysis of multidrug-resistant Salmonella enterica Infantis isolates in England and Wales

“…S. enterica Infantis has been the most prevalent serovar isolated from fresh poultry meat and broiler flocks from across Europe [6,54] and human S. enterica Infantis infections are often associated with poultry meat [2,6,[55][56][57][58]. Between 2014 and 2018 in England and Wales, human salmonellosis associated with S. enterica Infantis has been increasing, and this serovar has now become the fifth most widespread after S. enterica Enteritidis (n=12 548, 290.6 %), S. enterica Typhimurium including monophasic (n=7930, 180.7 %), S. enterica Newport (n=1372, 30.2 %) and S. enterica Typhi (n=1120, 20.6 %) (PHE data).…”

“… enterica Infantis has been the most prevalent serovar isolated from fresh poultry meat and broiler flocks from across Europe [6, 54] and human S . enterica Infantis infections are often associated with poultry meat [2, 6, 55–58]. Between 2014 and 2018 in England and Wales, human salmonellosis associated with S .…”