Isolation and antimicrobial resistance of Escherichia coli isolated from farm chickens in Taif, Saudi Arabia.

OBJECTIVES: Poultry is one of the main sources of food in the world. Antimicrobial-resistant Escherichia coli can be transmitted to humans by contact with poultry waste or by contaminated poultry products, contributing to the increasing crisis of antimicrobial resistance. This study aimed to determine the incidence of antimicrobial resistance in E. coli isolated from chickens in Taif province, Saudi Arabia, and to identify the genes responsible for any resistance observed. METHODS: A total of 150 cloacal swabs were aseptically obtained from chickens from different farms, from which 180 colonies of E. coli were identified using standard microbiology procedures. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method. The genes blaSHV, aac(3)-IV, tet(A), tet(B), aadA1, catA1, cmlA, ere(A) and sul1 were detected by PCR. RESULTS: Most of the E. coli isolates showed resistance to oxacillin (99%), lincomycin (98%) and oxytetracycline (97%). The prevalence of resistance to chloramphenicol (73%), ciprofloxacin (59%) and ampicillin (51%) was lower. Genes conferring resistance to ß-lactams (blaSHV) and tetracyclines [tet(A) and tet(B)] were observed at prevalences of 96% and 95%, respectively, among the E. coli isolates. Chloramphenicol (catA1 and cmlA) and erythromycin [ere(A)] resistance genes showed prevalences of 72% and 15%, respectively, whereas gentamicin [aac(3)-IV], streptomycin (aadA1) and sulfonamide (sul1) resistance genes were detected in 20%, 20% and 10% of the studied isolates, respectively. CONCLUSION: A significant prevalence of antimicrobial resistance genes was observed among E. coli isolates from farm chickens, supporting strict regulatory procedures for the use of antimicrobial agents.

Bacterial load of fresh vegetables and their resistance to the currently used antibiotics in Saudi Arabia.

This study was carried out to describe the bacterial load and the occurrence of some disease-causing enteric bacteria on raw vegetables sold in Saudi markets. The study further aimed to analyze antibiotic resistance rates, production of extended-spectrum beta lactamase, and plasmid carriage among bacterial population of raw vegetables. Results revealed that none of them contained Bacillus cereus, Salmonella, and Escherichia coli O157:H7. However, Staphylococcus aureus and Shigella were detected in 11.8% and 4.4% of the samples, respectively. The bacterial loads ranged from 3 to 8 log(10) CFUg(-1) for aerobic bacteria and 1 to 4 log(10) CFUg(-1) for coliforms as well as Enterobacteriaceae. The isolates exhibited resistance in decreasing order for ampicillin (76.5%), cephalothin (69.5%), trimethoprime-sulfamethoxazole (36.7%), aminoglycosides (21.9%), tetracycline (17.2%), fluoroquinolones (17.2%), amoxycillin-clavulanic acid (13.3%), and chloramphenicol (7.8%). Maximum resistance to extended-spectrum beta-lactam antibiotics occurred in 14.8% of isolates and the production of extended-spectrum beta-lactamase was achieved by 2.3% of isolates. Multiple resistances to four or more antimicrobial agents along with plasmid with varied sizes were documented. These investigations indicate the occurrence of antibiotic resistance and plasmid carriage among bacterial isolates populating raw vegetables.

Antibiotic resistance in Escherichia coli isolated from retail raw chicken meat in Taif, Saudi Arabia.

The present study was carried out to screen and analyze the genetic characteristics of antibiotic resistance in Escherichia coli strains isolated from chicken meat marketed in the local markets of the Taif region in Saudi Arabia. A total of 119 samples were purchased from various supermarkets and examined for bacterial contamination with resistant E. coli. Thirty-seven E. coli isolates were evaluated for their antibiotic susceptibilities and the presence of class 1 integrons and antibiotic resistance genes. Results of antibiograms revealed that E. coli isolates were resistant to one or more of the antibiotics tested. Resistance was most frequently observed against sulphafurazole (89.2%), ampicillin (78.4%), nalidixic acid (70.3%), streptomycin (48.6%), chloramphenicol (32.4%), and gentamicin (24.3%). Fifteen E. coli strains have multidrug resistance phenotypes and harbored at least three antibiotic resistance genes. The bla(TEM) (beta-lactamase) and sul (sulfonamide) resistance encoding genes were detected in all the tested isolates. Polymerase chain reaction screening detected class 1 integrons in all multiresistant E. coli isolates. The present study provides an assessment of the occurrence of multidrug resistance of E. coli from raw chicken meat collected from local markets.

Optimization of bacteriocin production by Lactobacillus plantarum AA135.

Growth of Lactobacillus plantarum AA135 in MRS broth at 30 degrees C yielded maximal plantaricin AA13 activity of 10000 AU/ml at pH 3.8 after 16 hours. Maximal activity (10000 AU/ml) of plantaricin AA13 was recorded in MRS broth at initial pH of 5 or 5.5. Optimal production (10000 AU/ml) was recorded in the presence of tryptone (20 g/l), a combination of tryptone plus meat extract (1:0.6) or tryptone with yeast extract (1:0.6) as sole nitrogen source. Growth of Lactobacillus plantarum AA135 in the presence of 20 g/l glucose yielded bacteriocin activity of 10000 AU/ml. Moreover, when 40 g/l glucose was added, the plantaricin AA13 levels doubled to 20000 AU/ml. Concentrations of 5, 10 and 20 g/l K2HPO4 lowered bacteriocin activity by 60%. Supplementing MRS with 1 g/l or more glycerol repressed bacteriocin production. Maximal activity of 20000 AU/ml was recorded in MRS supplemented with Vitamin DL-6,8-thioctic acid.