1. The increase in microbial resistance, and in particular multiple drug resistance (MDR), is an increasing threat to public health. The uncontrolled use of antibiotics and antibacterial chemotherapeutics in the poultry industry, especially in concentrations too low to cause inhibition, and the occurrence of residues in feed and in the environment play a significant role in the development of resistance among zoonotic food-borne microorganisms.
2. Determining the presence and transmission methods of resistance in bacteria is crucial for tracking and preventing antibiotic resistance. Horizontal transfer of genetic elements responsible for drug resistance is considered to be the main mechanism for the spread of antibiotic resistance.
3. Of the many well-known genetic elements responsible for horizontal gene transfer, integrons are among the most important factors contributing to multiple drug resistance. The mechanism of bacterial drug resistance acquisition through integrons is one of the essential elements of MDR prevention in animal production.
Salmonella enterica subsp. enterica serovar Eppendorf, with antigenic formula 1,4,12,[27]:d:1,5, is an infrequent serovar. However, 14% (20 of 142) of the isolates recovered during June–July 2012 in chicken farms in Tunisia belonged to S. Eppendorf. These isolates were analysed for resistance and virulence profiles. None of them were susceptible to all antimicrobials tested, while 70%, 60%, 50%, 50%, 20% and 5% were resistant to sulphonamides (sul1, sul2 and sul3), streptomycin (aadA1‐like), trimethoprim (dfrA1‐like), nalidixic acid (GyrA Asp87→Asn and not identified), gentamicin (not identified) and ampicillin (blaTEM‐1‐like). About 30% of the isolates showed decreased susceptibility to ciprofloxacin and carried the qnrB gene; 65% of the isolates were multidrug resistant and contained class 1 integrons with sul1 or sul3 in the 3′ conserved segment. The orgA, ssaQ, mgtC, siiD and sopB virulence genes located on SPI1 to SPI5 and the fimbrial bcfC gene were present in all isolates; the sopE1 and sodC1 carried by prophages were variably detected; however, the prophage gipA gene and the spvC gene of serovar‐specific virulence plasmids were absent. Altogether, ten resistance and three virulence profiles were identified. Typing of the isolates with XbaI‐ and BlnI‐PFGE supports a close relationship, although they appear to be evolving under selective pressure probably caused by antimicrobial use in chicken husbandry. As far as we know, this is the first study investigating the molecular bases of antimicrobial drug resistance, the virulence gene content and the PFGE profiles of S. Eppendorf. The epidemiological surveillance of this serovar would be necessary to evaluate its possible impact on human health, particularly in Tunisia and other African countries where it was already reported. 相似文献
For the sustainable farming of tilapia, proper maintenance of their health and adequate treatment for infections at appropriate time are inevitable. The indiscriminate use of antibiotics in aquaculture, as a part of treatment and as growth promoters, accelerates antimicrobial resistance (AMR) among the fish pathogens. In the present study, we have isolated diverse aeromonads from Nile tilapia and studied their antibiogram and plasmid profiling. Aeromonas hydrophila, Aeromonas veronii, Aeromonas sobria, Aeromonas dhakensis, Aeromonas caviae, Aeromonas jandaei and Aeromonas aquatica were isolated from infected tilapia (n = 150), and their Shannon wiener diversity index was calculated as 1.926. A. veronii was found to be the most multiple antibiotic‐resistant pathogen with the MAR index of 0.46, and A. aquatica was noticed as the least resistant isolate. The minimum inhibitory concentration of resistant antibiotics was shown as >256 mcg/ml for most of the isolates. The virulent genes such as aerolysin and hemolysin were identified in all the isolates except A. aquatica. The detection of class 1 integrons, plasmid profiling and plasmid curing studies confirmed that AMR exhibited by most of the Aeromonas species is of plasmid mediated. This challenges the risk of wide spread of AMR among the pathogens and subsequent treatment of the infection. 相似文献
This study determined the
antimicrobial resistance profiles of Escherichia coli isolates from dogs
with a presumptive diagnosis of urinary tract infection (UTI). Urine samples from 201 dogs
with UTI diagnosed through clinical examination and urinalysis were processed for
isolation of Escherichia coli. Colonies from pure cultures were
identified by biochemical reactions (n=114) and were tested for susceptibility to 18
antimicrobials. The two most frequent antimicrobials showing resistance in Urinary
E. coli isolates were oxytetracycline and ampicillin. Among the
resistant isolates, 17 resistance patterns were observed, with 12 patterns involving
multidrug resistance (MDR). Of the 69 tetracycline-resistant E. coli
isolates, tet(B) was the predominant resistance determinant and was
detected in 50.9% of the isolates, whereas the remaining 25.5% isolates carried the
tet(A) determinant. Most ampicillin and/or amoxicillin-resistant
E. coli isolates carried blaTEM-1 genes.
Class 1 integrons were prevalent (28.9%) and contained previously described gene cassettes
that are implicated primarily in resistance to aminoglycosides and trimethoprim
(dfrA1, dfrA17-aadA5). Of the 44 quinolone-resistant
E. coli isolates, 38 were resistant to nalidixic acid, and 6 were
resistant to nalidixic acid, ciprofloxacin and enrofloxacin. Chromosomal point mutations
were found in the GyrA (Ser83Leu) and ParC (Ser80Ile) genes. Furthermore, the
aminoglycoside resistance gene aacC2, the chloramphenicol resistant gene
cmlA and the florfenicol resistant gene floR were also
identified. This study revealed an alarming rate of antimicrobial resistance among
E. coli isolates from dogs with UTIs. 相似文献