Data on antibiogram and resistance genes harboured by Salmonella strains and their Pulsed-field gel electrophoresis clusters

This article describes the Pulsed-field gel electrophoresis clustering of the predominant Salmonella strains (Salmonella ser. Albany, Salmonella ser. Brancaster, and Salmonella ser. Corvallis) isolated from poultry and processing environment in wet market and small-scale processing plant in Penang and Perlis, the northern states of Malaysia. Agar disk diffusion assay was performed to determine the phenotypic antibiotic resistance of these Salmonella strains. The most common antibiograms among the three predominant Salmonella serovars were reported. The presence of integrase genes and antibiotic resistance genes conferring to resistance against β-lactams, aminoglycosides, tetracyclines, quinolones, sulphonamides and chloramphenicol, was detected via PCR amplification.


Subject area
Microbiology More specific subject area Foodborne pathogen Type of data Table  How data was  acquired Antibiograms were determined using the agar disk diffusion assay. Antibiotic resistance genes were detected using PCR (TProfessional Standard Gra-dient96 Thermocyler, Biometra, Germany). Typing of the Salmonella strains was performed using Pulsed-field gel electrophoresis (PFGE) (

Value of the data
The data on the presence of multidrug-resistant Salmonella in poultry and processing environment is a good indicator to extensive use of antibiotic in poultry.
DNA fingerprinting will help in understanding the Salmonella contamination patterns. The data is a good indicator for the government to create a national surveillance program focusing on monitoring the antibiotic resistance profiles and DNA fingerprinting of foodborne Salmonella in poultry and processing environment.
The data will aid in the discussion of the potential dissemination of antibiotic resistance genes in poultry and processing environment. Table 1 lists the antibiograms of multidrug-resistant (MDR) S. Corvallis, S. Brancaster and S. Albany strains isolated from poultry and processing environment in northern Malaysia. The Microsoft Excel Worksheet that is provided as Supplementary data (Table S1) for this article lists the antibiotic resistance and integrase genes harboured by these Salmonella strains, and the PFGE clustering of these strains.

Salmonella strains
Salmonella enterica subsp. enterica strains used in this study were previously isolated from a total of 182 poultry and environmental samples collected from wet markets and small-scale processing plant located in Penang and Perlis, the northern states of Malaysia. Seventeen different Salmonella Table 1 Antibiograms of MDR S. Corvallis, S. Brancaster and S. Albany strains isolated from poultry and processing environment in northern Malaysia.

Serovar
Antibiogram a MDR No. of isolates serotypes were isolated and the predominant serotypes were S. ser. Albany, S. ser. Brancaster and S. ser. Corvallis [2]. In this study, 114 representative strains of these three predominant serotypes, S. Albany (n ¼ 53), S. Brancaster (n ¼ 35) and S. Corvallis (n ¼ 26), were randomly selected for the following studies described below.

Pulsed-field gel electrophoresis
PFGE was conducted according to the standard operating protocol described by PulseNet, CDC [3]. DNA of Salmonella strains were digested with 50 U of restriction enzyme XbaI (Vivantis, Malaysia), at 37°C for 2 h. DNA electrophoresis was performed on 1% (w/v) agarose gel in a CHEF Mapper system (BioRad, Hercules, CA) with 0.5 × Tris-Borate EDTA buffer. The gel was run for 20 h at 14°C using a linear ramp of 2.16-63.8 s at 6 V/cm. XbaI-digested Salmonella Braenderup H9812 was used as the DNA size marker. PFGE data were processed using Bionumerics software version 7.0 (Applied Maths, Kortrijk, Belgium) and clustering of the fingerprints was performed as previously described [4].

Agar disk diffusion assay
Agar disk diffusion assay was performed by using commercially available antibiotic disks (Oxoid, Basingstoke, UK) on Mueller-Hinton agar (Oxoid, Basingstoke, UK) according to the guidelines of the CLSI [5]. Escherichia coli ATCC 25922 was employed as a positive control. The diameter of inhibition zones was measured and interpreted as resistant by referring to breakpoints suggested by CLSI [5]. Salmonella strains classified as intermediate susceptible on the basis of inhibition zone were considered as sensitive for resistance spectrum. Strain that was resistant to more than two types of antibiotic was regarded as MDR [1].

Detection of antibiotic resistance and integrase genes using PCR
Genomic DNA was prepared by using phenol-chloroform extraction method, adapted from Santos et al. [6] with modifications. PCR reaction mixtures were prepared as described by Benacer et al. [7] and amplification was performed using a TProfessional Standard Gradient96 Thermocyler (Biometra, Germany). The presence of integrase genes and antibiotic resistance genes conferring to resistance against β-lactams, aminoglycosides, tetracyclines, quinolones, sulphonamides and chloramphenicol, was detected using primers previously reported [8].