Class 1 Integrons and Salmonella Genomic Island 1 Among Salmonella enterica Isolated from Poultry and Swine

Abstract

Two hundred eleven Salmonella enterica strains representing 35 serotypes isolated from healthy poultry (n=103) and swine (n=108) were used in this study. The occurrence and characteristics of class 1 integrons were investigated. Salmonella genomic islands (SGIs) and the horizontal transfer of integrons were assessed. One hundred eighty-six isolates (88%) were resistant to at least one antimicrobial and 140 isolates (66%) were multidrug resistant. The intI1 gene was present in 54 isolates (25.6%), of which 33 (15.6%) carried gene cassettes with sizes ranging from 0.7 to 2.3 kb. Sequence analysis revealed 11 distinct integron profiles in which resistance genes bla(PSE-1), dfrA1, dfrA12, aadA2, aadA4a, and silB were present. The gene cassette array dfrA12-aadA2 was the most prevalent among the isolates whereas most integrons were located on conjugative plasmids. SGI1 variants (SGI1-A and -F) were present in nine isolates belonging to serovars Albany, Emek, Kedougou, and Kingston.

Antimicrobial Resistance Genes in Salmonella enterica Isolates from Poultry and Swine in Thailand

“…A total of 184 Salmonella isolates previously isolated were studied [8,15]. They were originated from poultry (n=80) and swine (n=104) and comprised of 34 serotypes including 24 [2005][2006].…”

“…All of the isolates used were previously classified as resistant to at least one antimicrobial agent [15]. Resistance rates to ampicillin, chloramphenicol, ciprofloxacin, gentamicin, spectinomycin, streptomycin, sulfamethoxazole, tetracycline and trimethoprim were 56%, 32%, 2%, 14%, 56%, 69%, 76%, 66% and 38%, respectively.…”

“…Fifty-three percent of the isolates were resistant to 3 different classes of antimicrobials or more and considered multidrug resistance (MDR). Fifteen percent of the Salmonella strains carried class 1 integrons with resistance gene cassettes and 5% of the isolates harbored SGI1-A or -F [15].…”

“…In our previous study, the prevalence, molecular characteristics and transferability of class 1 integrons in S. enterica from healthy swine and poultry were investigated [15]. In this study, we further characterized the molecular mechanisms of multidrug resistance among the Salmonella isolates.…”

Antimicrobial resistance, presence of integrons and biofilm formation ofSalmonellaPullorum isolates from eastern China (1962–2010)

“…Integrons are capable of capturing and mobilizing antimicrobial resistance bacterial genes. Class 1 and class 2 integrons are the most common integron types identified in Salmonella and play an important role in the dissemination of resistance genes among these pathogens (Orman et al, 2002;Antunes et al, 2006;Khemtong & Chuanchuen, 2008). Likewise, biofilms are important factors in antimicrobial resistance, and play a key role in the pathogenesis of many bacterial infections.…”