No abstract

A study was conducted in the Beirut, Lebanon, Water Treatment Plant to determine the dose of chlorine lethal to algae which were causing operational difficulties in the Plant. In laboratory experiments, it was found that a single dose of 1.8 mg/1 of chlorine was sufficient to kill all the algal taxa growing in the plant. If the chlorine dose was regenerated to the original concentration every 24 hours, then a dose of 1.2 mg/1 was sufficient. In field studies, continuous dosing of chlorine to maintain a residual chlorine level of 0.8 mg/1 was found lethal to the algal taxa. Prechlorination is therefore recommended as an effective method for the control of algal growth in conventional water treatment plants.

Background QTc interval prolongation has been reported when combining fluoroquinolones and triazoles for chemoprophylaxis in cancer patients. Herein, we aimed to identify the prevalence and contributing factors to QTc prolongation in hematopoietic cell transplantation (HCT) recipients who received these agents during the neutropenic phase. Methods This is a retrospective medical chart review conducted at a university hospital in Lebanon from 2017 to 2020. It included all adult HCT inpatients on antimicrobial prophylaxis with fluoroquinolones and triazoles and whose baseline ECG monitoring done prior to chemoprophylaxis administration, then on day-3 and day-6 of therapy, were available. Results Overall, 68 HCT recipients met our inclusion criteria, of which 22% developed QTc prolongation. Based on bivariate analysis, female gender contributed to QTc prolongation ( P = 0.001). There was a trend to QTc prolongation in patients with predisposing thyroid disease ( P = 0.12), grade 2 vomiting and diarrhea ( P = 0.16, P = 0.46, respectively), baseline hypokalemia ( P = 0.18) and hypocalcemia ( P = 0.3), hypomagnesemia on day-3 ( P = 0.21) and day-6 hyponatremia ( P = 0.36). Patients receiving two or more drugs with a known or probable risk of QTc prolongation (other than the fluoroquinolone/ triazole combination) were more prone to experience a prolonged QTc interval ( P = 0.09). None of the patients that had QTc prolongation died or developed serious arrhythmias. Conclusion The prevalence of QTc prolongation was 22% among HCT recipients on fluoroquinolone and triazole prophylaxis, yet we did not identify any independent risk factors for this issue. None of the patients that had QTc interval prolongation died or developed serious arrhythmias.