Horizontal Transfer of a Multi-Drug Resistance Plasmid between Coliform Bacteria of Human and Bovine Origin in a Farm Environment

Abstract

Multi-drug-resistant coliform bacteria were isolated from feces of cattle exposed to antimicrobial agents and humans associated with the animals. Isolates from both cattle and humans harbored an R plasmid of 65 kb (pTMS1) that may have been transferred between them due to selective antibiotic pressure in the farm environment.The amount of antimicrobial agents used for therapeutic and nontherapeutic purposes in agriculture far exceeds what is used for humans in many parts of the world (11). Since exposure to antimicrobial agents is the most important factor with regard to development of antimicrobial resistance, animals and animal products could thus be significant sources of resistant bacteria for the human population (1,5,12,17,18). Nonpathogenic, multiple-drug-resistant Escherichia coli in the intestine is probably an important reservoir of resistance genes (3,10,13,15,21), and drug-resistant, intestinal E. coli of animal origin may colonize the human intestine, at least temporarily (14,15,20). However, the ease with which bacteria acquire new resistance genes by self-transmissible and mobilizable plasmids and conjugative transposons may represent a more significant contribution to the increasing incidence of resistant strains (19,23,24).In this study, farm inhabitants were investigated for the occurrence of multi-drug-resistant intestinal E. coli. On the farm studied here, various antimicrobials had been used extensively, primarily to treat recurrent Staphylococcus aureus mastitis in dairy cattle (L. Sølverød, personal communication). One family lived on the farm, and one veterinarian had served the animals. During the spring of 1996, fecal swabs (Culturette; Becton Dickinson Europe, Meyland, France) were collected from 13 cattle, three family members, and the local veterinarian. One year later, sampling of the family members and the veterinarian was repeated, and fecal swabs from four other veterinarians operating sporadically in the area were also included. For a primary screening of the total aerobic fecal flora, each swab was plated onto blood agar (blood agar base [Difco Laboratories, Detroit, Mich.] containing 5% citrated bovine blood) and Mueller-Hinton agar (Difco) with Neo-Sensitabs (Rosco Diagnostica, Taastrup, Denmark) containing 33 g of ampicillin (AMP), 80 g of tetracycline (TET), 100 g of streptomycin (STR), 5.2 g of trimethoprim (TMP), 240 g of sulfonamides (SUL), 60 g of chloramphenicol, and 10 g of enrofloxacin. Agar plates were incubated at 37°C for 24 h. A total of six cattle and five human samples exhibited multipledrug-resistant patterns (Amp r Tet r Str r Tmp r Sul r ). From these plates, three colonies were picked from the zones close to the Neo-Sensitabs containing AMP, TET, and SUL, respectively. Colonies were subcultivated on blood agar and BTB-lactose agar plates to assure pure cultures and retested for susceptibility to the above-mentioned antimicrobials. MICs of AMP, TET, STR, TMP, and SUL were determined (16). A total of 39 of 90 lactose-fermenting (coliform) bovine and human iso...

Microbiological quality of organic vegetables produced in soil treated with different types of manure and mineral fertilizer

“…Composting and drying of Reporting of foodborne disease associated with changes in agricultural practices or eating habits, as well as queries on how the pathogens spread from manure to environment; and, the relations between soil microbial population and with vegetal tissue are recent. Furthermore, the chance of antimicrobial resistance being transferred is of great relevance in pathogen emergence and re-emergence (10,16,45,48,55,57,59,64).…”

Isolation and characterization Shiga toxin-producing Escherichia coli from sheep and goats inJordanwith evidence of multiresistant serotype O157:H7

“…The finding of four different R types of STEC O157:H7 on the sheep Farm A is indicative of a selective pressure of several groups of antimicrobial substances on the farm related to treatment some time in the past. If sanitary regulations are not observed, the conditions on such farms are such that a transmission of resistant STEC strains to people, or at least of a transmission of multiresistance encoding determinants from coliform bacteria of animal origin to human strains, may take place (Oppegaard et al, 2001). The results obtained in the study again confirmed the fact that such risks are high in countries where an antibiotic control strategy is missing and the use of antibiotics is not regulated.…”

“…Just as with other agents of human alimentary infections caused by Salmonella typhimurium DT 104 (Threlfall, 2002) and Campylobacter jejuni (Swartz, 2002), the STEC strains resistant to antibiotics of the first choice may complicate antimicrobial therapy whose timely application may prevent the development of life-threatening HUS in human STEC infections (Shiomi et al, 1999). Besides having clinical consequences, resistant E. coli strains of animal origin may be the source of determinants of resistance for the possible transfer to human strains (Oppegaard et al, 2001).…”

Similarity in the Structure of <i>tetD</i>-Carrying Mobile Genetic Elements in Bacterial Strains of Different Genera Isolated from Cultured Yellowtail

“…The only possible explanation is horizontal gene transfer, since conjugative plasmids can be transferred across different genera when no distance barrier exists. Horizontal gene transfer in the environment has been suggested by the structure homologies of mobile genetic elements and antibiotic resistance genes Hartman et al, 2003;Heuer et al, 2009;Oppegaard et al, 2001 . Geographic isolation of fish farm C from A approx.…”