Detection of class 1 integrons in Salmonella Weltevreden and silent antibiotic resistance genes in some seafood-associated nontyphoidal isolates of Salmonella in south-west coast of India

Abstract

Aims: To study the antibiogram of 40 seafood isolates of Salmonella and use of PCR to detect the presence of integrons and genes coding for antibiotic resistance. Methods and Results: In this study, 40 isolates of Salmonella were used for antibiogram analysis. The multidrug‐resistant isolates were analyzed for the presence of integron using integron‐specific primers. Twenty‐five percentage of the isolates were multidrug resistant while 67·50% were resistant to at least two antibiotics. Antibiotic resistance genes catA1 and tetA were present in 57·52 and 60%, respectively. Although widespread presence of genes was observed, only 26·08% of the catA1‐carrying isolates exhibited phenotypic resistance against the respective antibiotic. Integrons present in representative isolates of Salmonella Weltevreden and Salmonella Newport were sequenced. The former contained class 1 integron with a single gene dfrA7 in the integron cassette and an adjacent dihydropteroate synthetase gene along with the usual quaternary ammonium compound resistance gene, while the later contained class 1 integron with dhfrA1, OrfC, in the integron cassette and an adjacent dihydropteroate synthetase gene along with the usual quaternary ammonium compound resistance gene. Conclusions: This study demonstrates the presence of silent antibiotic resistance genes and class I integrons in seafood‐associated Salmonella strains. The study also demonstrates the first report of class I integron in Salm. Weltevreden. Detection of catA1 genes in phenotypically sensitive bacteria suggests that these could be reservoirs in the environment. Significance and Impact of the Study: The manuscript provides novel results describing the existence of a high rate of antibiotic resistance in the Salmonella populations prevailing in environmental sources as well as an absence of correspondence between the presence of antibiotic resistance genes, and the exhibition of a the corresponding phenotypic trait of resistance against the respective antibiotic compound was observed. In addition, the manuscript reports the presence of the class I integron in Salm. Weltevreden.

Antimicrobial‐resistant genes associated with Salmonella spp. isolated from human, poultry, and seafood sources

“…Thus the present results and those of Deekshit et al. () agree that some antimicrobial‐resistant genes are “silent” in bacteria in vitro; it further provides an indication that these silent genes can spread to other bacteria or turn on in vivo, especially under selection pressure of antibiotic use (Yaqoob et al. ).…”

“…Resistance to traditional antibiotics (AMP, TET, and SUL) was high in Salmonella isolates from animals and foods of animals as observed in this study, previously reported by Deekshit et al. (). It is apparent that resistance to traditional antibiotics such as TETs, AMPs, and cotrimoxazole and detection of their genes in microbial populations of both countries constitute a public health concern by limiting the therapeutic choices for treating salmonellosis in animals and humans.…”

Alternate antimicrobial resistance genes in multidrug resistant Salmonella spp. isolated from retail meats in Vietnam using RNA‐sequencing analysis

“…In this study, approximately 52% of the isolates were resistant to at least one antibiotic, which was higher than other studies in Poland (42.6%; Maka et al, 2015), but lower than figures reported in Tokyo (89.9%; Katoh et al, 2015) and India (67.5%; Deekshit et al, 2012). The overall rate of multi antimicrobial resistance was 36%, which was higher than that described in Korea (29%; Choi et al, 2015) and India (25%; Deekshit et al, 2012), but lower than figures reported in Romania (71.4%; Tirziu et al, 2015), Japan (90.2%; Katoh et al, 2015), and Colombia (98%, Donado-Godoy et al, 2015). The cause of this difference could be attributed to the abuse of antibiotics used in animal feed, used in treatment and prevention of livestock diseases on farms, and use in treatment of human patients, all of which has increased the rate of resistance genes for microorganisms (Miranda, Mondragon, Martinez, Guarddon, & Rodriguez, 2009).…”

Differential expression of virulence genes and role of gyrA mutations in quinolone resistant and susceptible strains of Salmonella Weltevreden and Newport isolated from seafood

“…In wild quinolone resistant isolates (SN36 and SW9), the decreased growth rate, invasion and survival inside the HeLa cell may also be due to other factors such as presence of class 1 integron or their resistance to other antibiotics as reported in a previous study on the same isolates by Deekshit et al . (). Molecular mechanism of how particular mutations in the QRDR region ( gyrA , gyrB , parC and parE ) improve or decrease the growth rate or expression of particular virulence associated genes of SPIs need further study.…”