RESUMEN
Reduced susceptibility of Clostridium difficile to antibiotics is problematic in clinical settings. There is new evidence indicating the cotransfer of toxin-encoding genes and conjugative transposons encoding resistance to antibiotics among different C. difficile strains. To analyze this association, in the current study, we evaluated the frequency of toxigenic C. difficile among the strains with different multidrug-resistant [MDR] profiles in Iran. Antimicrobial susceptibility patterns and minimal inhibitory concentrations [MIC] of the isolates were determined against metronidazole, imipenem, ceftazidime, amikacin, and ciprofloxacin by agar dilution method. The association of the resistance profiles and toxigenicity of the strains were studied by PCR targeting tcdA and tcdB genes. Among 86 characterized strains, the highest and lowest resistance rates were related to ciprofloxacin [97%] and metronidazole [5%], respectively. The frequency of resistance to other antibiotics was as follow: imipenem [48%], ceftazidime [76%], and amikacin [76.5%]. Among the resistant strains, double drug resistance and MDR phenotypes were detected in the frequencies of 10.4% and 66.2%, respectively. All of the metronidazole-resistant strains belonged to tcdA [+]/tcdB[+] genotype with triple or quintuple drug resistance phenotypes. MIC[50] and MIC[90] for this antibiotic was equally
RESUMEN
In this study, genetic polymorphism of two tRNA-liked short tandem repeat [STR]-containing loci, R-R and S-Q, was analyzed in order to clarify further the genotypic differences among E. dispar isolates. Entamoeba dispar is closely related to the human pathogen E. histolytica, the agent of amebic dysentery and amebic liver abscesses. E. dispar is, to some extent, capable of producing variable focal intestinal lesions in animals and of destroying epithelial cell monolayers in vitro, and some have reported it to be capable of producing amoebic liver abscess in hamsters. However no evidence exists at present to link E. dispar with human disease. A total of 28 E. dispar samples from gastrointestinal disorder patients were characterized using PCR and sequencing. The sequences obtained were edited manually and aligned. Sequence analysis showed 9 and 6 different patterns of units in the repeat-containing region of R-R and S-Q, respectively. The repeat-containing regions of R-R and S -Q loci were found to be extensively polymorphic, varying in size, number and order of repeat units. The results demonstrate extensive genetic variability among Iranian E. dispar clinical isolates. The genetic diversity of tRNA gene-linked STR loci shows them to be suitable for epidemiological studies such as the characterization of the routes of transmission of these parasites in Iran