Prevalence of trimethoprim resistance genes in Escherichia coli isolates of human and animal origin in Lithuania

Abstract

A total of 456 non-repetitive Escherichia coli isolates from human clinical specimens (urinary, n5134; cervix, vagina and prostate, n552; blood, pus and wounds, n545), healthy animals (cattle, n545; poultry, n520) and diseased animals (cattle, n553; swine, n564; poultry, n543) obtained in Lithuania during the period 2005-2008 were studied for trimethoprim (TMP) resistance and the prevalence of dfr genes. A TMP resistance rate in the range of 18-26 % respective to the origin was found in clinical isolates, 23-40 % in isolates from diseased animals and 9-20 % in isolates from healthy animals. Of 112 TMP-resistant isolates, 103 carried at least one of the six dfrA genes (dfrA1, dfrA5, dfrA8, dfrA12, dfrA14 and dfrA17) as determined by multiplex PCR and RFLP. The dfrA1 and dfrA17 genes were found most frequently in clinical isolates (17 and 19 isolates, respectively), whilst dfrA1 and dfrA14 genes dominated in isolates of animal origin (25 and 13 isolates, respectively). The dfrA5, dfrA12 and dfrA8 genes were detected at lower frequencies. The association with class 1/class 2 integrons was confirmed for 73-100 % of dfr genes found in most groups of isolates, except for the isolates from diseased swine. In this group, the majority of dfr-positive isolates (67 %, 8/12) carried dfrA8 (6/12) or dfrA14 genes (2/12) that were not associated with integrons. Non-integron location was also confirmed for the remaining dfrA8 genes (six clinical isolates and one isolate from diseased cattle) and for dfrA14 genes (two isolates from diseased cattle and swine each). All cassetteindependent dfrA14 genes were found to be located within the strA gene. This study on the prevalence and distribution of TMP resistance genes among E. coli isolates of human and animal origin in Lithuania demonstrates that dfr genes are carried most frequently as gene cassettes within class 1 and/or class 2 integrons. However, TMP resistance in some of the isolates was found to be mediated by non-integron-associated dfrA8 and dfrA14 genes, indicating the existence of alternative sources for the spread of resistance.

High prevalence of multidrug-resistance in Acinetobacter baumannii and dissemination of carbapenemase-encoding genes blaOXA-23-like, blaOXA-24-like and blaNDM-1 in Algiers hospitals

“…Simplex and multiplex PCR were used to screen for the following resistance genes as previously described: OXA carbapenemases: bla OXA-51-like , bla OXA-23-like , bla OXA-24-like , bla OXA-58-like [12] and bla OXA-143 [13]; metallo-b-lactamases: bla IMP , bla VIM , bla GIM and bla NDM-1 [14,15]; cephalosporinase: bla ADC [16]; class A beta-lactamases: bla TEM , bla SHV [17], bla CTX-M [18], bla PER , bla VEB , bla GES [19]; plasmid-mediated quinolone resistance determinants: qnrA, qnrB and qnrS [20] ; aminoglycoside-modifying enzyme: aac(6 0 )-Ib [20] ; tetracycline efflux pumps: tetA and tetB [21] ; dihydropteroate synthases: sul1, sul2 and sul3 [22,23] ; dihydrofolate reductases: dfrA1, dfrA5, dfrA7, dfrA8 and dfrA12 [24] .…”

Whole-Genome Analysis of Antimicrobial-Resistant and Extraintestinal Pathogenic Escherichia coli in River Water

“…Eight of these dfr genes were detected in the present study, and dfrA17 was the most prevalent variant. This variant has been found frequently in clinical E. coli isolates and is known to be present as a gene cassette within class 1 integrons (37).…”

“…Trimethoprim resistance is explained mainly by the acquisition of a trimethopriminsensitive dihydrofolate reductase, which is the target enzyme of this agent (37). To date, more than 30 different dfr genes are known (35).…”

Characteristics of ciprofloxacin-resistant Enterobacteriaceae isolates recovered from wastewater of an Algerian hospital

“…Simplex and multiplex PCR were used to screen for the following resistance genes: plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qnrC, qnrD, aac-(6')-Ib, and qepA [14]; beta-lactamases blaOXA-1, blaTEM, and blaCTX-M [8,15]; tetracycline efflux pumps tetA, tetB, tetC, tetD, and tetE [15]; dihydropteroate synthases sul1, sul2, and sul3 [15]; dihydofolate reductase gene clusters dfrA1, dfrA5, dfrA7, dfrA8, and dfrA12 [16]; aminoglycosides adenyltransferases, acetyltransferases and phosphotransferases aadA1/2, aadA5, aac(3)II, aph(3')-Ia, aph(3')-IIa [15]; and mercuric reductase merA [17]. The screening for class 1 integrons was done by PCR targeting the int1 gene [8].…”