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The rapid emergence of multiresistant microbial pathogens, dubbed superbugs, is a serious threat to human health. Extended spectrum beta lactamase (ESBL)-producing Escherichia coli is a superbug causing worldwide outbreaks, necessitating timely and accurate tracking of resistant strains. Accordingly, this study was designed to investigate the spread of ESBL-producing Escherichia coli isolates, to analyze the effect of different genotypic and phenotypic factors on in vitro resistance patterns, and to assess the diagnostic value of commonly used ESBL genetic markers. For that purpose, we cultured 250 clinical isolates and screened their susceptibility to beta-lactam antibiotics. Among 12 antibiotics screened, only imipenem seems to have remained resilient. We subsequently analyzed the ESBL phenotype of Escherichia coli isolates and examined potential associations between their resistance phenotypes and patient-related factors. ESBL genotyping of 198 multiresistant isolates indicated that 179 contained at least one blaCTX-M gene. As we statistically dissected the data, we found associations between overall resistance and body site / type of disease. Additionally, we confirmed the diagnostic value of testing both blaCTX-M-1 and blaCTX-M-15 in providing better prediction of overall resistance. Finally, on sequencing the amplification products of detected blaCTX-M genes, we discovered two novel variants, which we named blaCTX-M-14.2 and blaCTX-M-15.2.

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Despite the nutritional significance of sulfur, its influence on biosurfactants production has not been sufficiently studied. We investigated the expression of key biosurfactants production genes, rhlABC, in cultures of Pseudomonas sp. AK6U grown with inorganic or organic sulfur sources. AK6U grew with either inorganic sulfate (MgSO4), dibenzothiophene (DBT), or DBT-sulfone as a sole sulfur source in the presence of glucose as a carbon source. The AK6U cultures produced variable amounts of biosurfactants depending on the utilized sulfur source. Biosurfactants production profile of the DBT cultures was significantly different from that of the DBT-sulfone and inorganic sulfate cultures. The last two cultures were very similar in terms of biosurfactants productivity. Biosurfactants yield in the DBT cultures (1.3 g/L) was higher than that produced by the DBT-sulfone (0.5 g/L) and the inorganic sulfate (0.44 g/L) cultures. Moreover, the surface tension reduction in the DBT cultures (33 mN/m) was much stronger than that measured in the DBT-sulfone (58 mN/m) or inorganic sulfate (54 mN/m) cultures. RT-qPCR revealed variations in the expression levels of the rhlABC genes depending on the sulfur source. The DBT cultures had higher expression levels for the three genes as compared to the DBT-sulfone and inorganic sulfate cultures. There was no significant difference in the expression profiles between the DBT-sulfone and the MgSO4 cultures. The increased expression of rhlC in the DBT cultures is indicative for production of higher amounts of dirhamnolipids compared to the DBT-sulfone and inorganic sulfate cultures. The gene expression results were in good agreement with the biosurfactants production yields and surface tension measurements. The sulfur source mediates a fine-tuned mechanism of transcriptional regulation of biosurfactants production genes. Our findings can have an impact on industrial production of biosurfactants and other biotechnological processes like biodesulfurization.

ObjectiveTo determine the incidence of symptomatic and ‘silent’ obstruction after ureteroscopic procedures.Patients and methodsIn all, 1980 patients underwent ureteroscopy for ureteric calculi in two large centres. The methods of disintegration, auxiliary procedures used and type of stenting were considered. Intraoperative complications, in addition to the size and site of the stone, were assessed in relation to postoperative obstruction. The mean (range) follow-up was 42 (12–68) months, with patients assessed after 3–6 months and yearly thereafter. The postoperative evaluation included an assessment of pain, renal ultrasonography, a plain abdominal film, intravenous urography, and a diuretic renal scan in some cases to confirm obstruction.ResultsThe success rate of stone removal was 98.5%. The failures were related to the size of the stone (>2 cm; P < 0.001). In eight patients there was a ureteric perforation, and six of these developed a ureteric stricture. A stricture also occurred in 12 patients (0.6%) during the follow-up; these included nine of 204 with stones of >2 cm (4.4%), compared to three (0.17%) of 1746 patients with stones of <2 cm (P < 0.001). Fourteen patients presented with pain (0.7%), and five had no obstruction, while in nine (0.46%) the pain was associated with obstruction. There was silent obstruction in three cases (0.15%). The negative and positive predictive values for pain were 99.8% and 64.3%, respectively.ConclusionsRadiographic surveillance for stricture formation and obstruction is mandatory in patients who are symptomatic after ureteroscopy, and for up to 18 months in patients with intraoperative complications or with a stone of >2 cm in the proximal ureter.