ABSTRACT
One hundred sixty Salmonella enterica isolates from clinically healthy dairy cows were assayed for antibiotic susceptibilities, the presence of class 1 integrons, antimicrobial resistance genes and virulence genes, and conjugal transfer of antimicrobial resistance determinants. One hundred nine (68%) of the Salmonella isolates were resistant to at least 1 antibiotic, and 14 isolates (9%) were multiresistant. The most prevalent resistance observed was to streptomycin (64%). Class 1 integrons were detected in only two Salmonella isolates (serovar Singapore and Derby), and both integrons harbored the same cassette content aadA2. The Derby class 1 integrons were associated with Salmonella genomic island 1-A. Most commonly found resistance genes were strA and strB (9.2%). None of class 1 integrons were horizontally transferred, and the resistance genes were successfully transferred from six (5.5%) Salmonella strains. One hundred fifty-nine isolates (98.8%) were positive to the invasion gene invA, whereas the virulence plasmid-associated genes spvC and pefA were found in only two (1.3%) and one (0.6%) Salmonella isolates, respectively.
Subject(s)
Cattle/microbiology , Dairying , Drug Resistance, Bacterial/genetics , Salmonella enterica/drug effects , Salmonella enterica/pathogenicity , Virulence/genetics , Animals , Conjugation, Genetic , Disease Reservoirs/veterinary , Drug Resistance, Multiple, Bacterial/genetics , Feces/microbiology , Foodborne Diseases/prevention & control , Gene Transfer Techniques , Genes, MDR , Genetic Variation , Integrons/genetics , Microbial Sensitivity Tests/statistics & numerical data , Polymerase Chain Reaction , Rectum/microbiology , Salmonella enterica/genetics , Salmonella enterica/isolation & purification , ThailandABSTRACT
Thirteen commercial probiotic feed products were examined for microbiological content and the results were compared with the information available on the product labels. Antibiotic resistance of Lactobacillus and Bacillus was investigated. All the products were inaccurately labelled in either numbers or species of bacteria. Misnaming at the species level was the most common flaw. Lactobacillus exhibited higher-antibiotic resistance than Bacillus did. Plasmid was found in both Lactobacillus (22%) and Bacillus (2.5%). The vanA gene was present in one L. plantarum and one B. subtilis isolate. The vanA-containing B. subtilis also harbored the tetW gene. None of the genes detected appeared to be associated with a conjugative plasmid.
Subject(s)
Animal Feed/microbiology , Bacillus/isolation & purification , Lactobacillus/isolation & purification , Probiotics/analysis , Animal Husbandry , Animals , Bacillus/drug effects , Bacillus/genetics , Bacterial Proteins/genetics , Carbon-Oxygen Ligases/genetics , DNA Primers , Drug Resistance, Bacterial , Genes, Bacterial , Lactobacillus/drug effects , Lactobacillus/genetics , Microbial Sensitivity Tests , Polymerase Chain Reaction , Quality ControlABSTRACT
The unusual 3' conserved sequence region of class 1 integrons was characterized in seven Salmonella isolates from swine and poultry. Three types of gene cassette arrays, aadA2-cmlA1-aadA1, sat-psp-aadA2-cm1A1-aadA1 and drfA12-orf-aadA2-cmlA1-aadA1, were found to be linked to a genetic organization qacH-IS440-sul3. All class 1 integrons were located on a conjugative plasmid that could be transferred to Escherichia coli. The results support the notion that the use of an antibiotic can select for resistance not only to that specific agent, but also to other unrelated antimicrobials including those that are no longer approved for use in food animal production.
Subject(s)
Drug Resistance, Multiple, Bacterial/genetics , Integrons/genetics , Salmonella enterica/genetics , Animals , Conjugation, Genetic , Conserved Sequence , Escherichia coli/drug effects , Escherichia coli/genetics , Microbial Sensitivity Tests , Polymerase Chain Reaction , Poultry , Salmonella enterica/drug effects , Salmonella enterica/isolation & purification , Sequence Analysis, DNA , SwineABSTRACT
A study was conducted to determine the presence of salmonellae in raw chicken meat, giblets (liver, heart, gizzard) and cooked chicken products (meatballs and sausages) in Bangkok. A total of 1,135 samples, collected from nine open markets, nine supermarkets and four poultry processing plants, were examined. Salmonellae were isolated from 467 (66%) of 705 chicken meat samples, 190 (86%) of 221 samples of giblets and 21 (10%) of 209 cooked products. Out of 678 tested isolates, 46 serotypes and one rough strain were found. The five most common serotypes isolated from chicken meat were Salmonella blockley , Salmonella virchow , Salmonella enteritidis , Salmonella hadar and Salmonella paratyphi B; these accounted for 14, 12, 12, 9 and 9%, respectively, of the strains isolated in this study. The major isolates from giblets were S. virchow , Salmonella Kentucky , S. enteritidis , Salmonella agona and S. blockley (15, 13, 12, 12 and 11%, respectively). Salmonella derby (33%) was the serotype most often isolated from the cooked poultry products.