Effective and selective electroreduction of aqueous nitrate catalyzed by copper particles on multi-walled carbon nanotubes.

Drinking-water contamination with nitrate ions is inevitable and wide spreading, which demands feasible removal. Water de-nitration by potentiostatic electroreduction is described here. A novel electrocatalyst based on nano-copper particles, supported onto multi-walled carbon nanotubes (MWCNTs), and spray-deposited onto fluorine doped tin oxide-glass substrates, is described. The Cu/MWCNT/FTO electrode has been characterized by several methods and assessed as a working electrode in aqueous nitrate ion electroreduction, in comparison with MWCNT sprayed on FTO (MWCNT/FTO) with no copper. Comparison with earlier reported electrodes is also described. XRD patterns confirm the presence of nano-copper crystallites, in the electrode, with average size ⁓45 nm. Within 2 h of electrolysis, Cu/MWVNT/FTO exhibits more than 65% removal of nitrate at -1.80 V (vs. SCE). In longer time (7 h) the electrode completely converts the nitrate into N2 (∼65%) and (NH4+) ∼35% with no NO2- ions. The kinetics show 0.76 order with respect to nitrate, and a rate constant 4.53 × 10-2 min-1 higher than earlier counterparts. The new electrode functions under various conditions of temperature, pH, electrolyte type and concentration and inter-electrode spacing, only at ambient applied potential. Moreover, the electrode exhibits stability under nitrate electroreduction conditions, and can be recovered and reused for multiple times without efficiency loss. XRD and EDS results also confirm the electrode stability after multiple reuse. Compared to earlier systems, the Cu/MWCNT/FTO is environmentally stable, safe, non-costly with high nitrate removal efficiency and selectivity.

Comparison of clinical prediction rules for management of pharyngitis in settings with limited resources.

OBJECTIVE: To compare the effectiveness of several clinical prediction rules for culture-positive streptococcal pharyngitis in a single group of patients in a setting in which clinicians routinely treat all cases of pharyngitis presumptively, without laboratory data. STUDY DESIGN: A MEDLINE search identified clinical prediction rules for streptococcal pharyngitis in children. Each rule was applied analytically to data from 410 children in Cairo, Egypt with clinical pharyngitis, in whom throat cultures were performed. The diagnostic effectiveness of these rules for predicting a positive culture were assessed and compared. RESULTS: Seven prediction rules were identified. Of these 7 rules, 4 were developed in North American children, 1 was recommended by the World Health Organization (WHO), and 2 were developed in Egypt. In the Cairo children, the WHO rule was the least sensitive, at 12%. The 6 other rules had sensitivities ranging from 81% to 99% and specificities ranging from 4% to 40%; 2 rules seemed to be effective, with diagnostic odds ratios of 5.2 and 6.1. CONCLUSIONS: The prediction rules demonstrated variable diagnostic effectiveness in the Egyptian children. Without laboratory testing, 2 clinical rules detected > 90% of cases of pharyngitis with positive culture for group A streptococcus and reduced overtreatment of culture-negative cases by approximately 40%. Selected clinical prediction rules have useful characteristics in settings of limited resources and need further validation.

Evaluation of the WHO clinical decision rule for streptococcal pharyngitis.

AIMS: To prospectively assess the WHO clinical decision rule (CDR) for group A beta haemolytic streptococcal (GABHS) pharyngitis in three countries. METHODS: A prospective, observational cohort study in urban outpatient clinics in Rio de Janeiro, Cairo, and Zagreb. There were 2225 children aged 2-12 years with cough, rhinorrhoea, red or sore throat; 1810 of these with sore throat were included in the analysis. RESULTS: The proportion of children presenting with sore throat and found to have GABHS pharyngitis ranged from 24.6% (Brazil) to 42.0% (Croatia). WHO CDR sensitivity was low for all sites in both age groups. In children age 5 or older, sensitivity ranged from 3.8% in Egypt to 10.8% in Brazil. In children under 5, sensitivity was low (0.0-4.6%) Specificity was high in both age groups in all countries (93.8-97.4%). CONCLUSIONS: In these populations, the current WHO CDR has high specificity, but low sensitivity; it did not detect up to 96.0% of children who have laboratory confirmed GABHS pharyngitis. A CDR with higher sensitivity should be developed for use in regions where rheumatic fever and rheumatic heart disease are still major health problems.

Effectiveness of clinical guidelines for the presumptive treatment of streptococcal pharyngitis in Egyptian children.

BACKGROUND: Primary prevention of acute rheumatic fever requires antibiotic treatment of acute streptococcal pharyngitis. In developing countries, clinicians must rely on clinical guidelines for presumptive treatment of streptococcal pharyngitis since bacterial culture and rapid diagnostic tests are not feasible. We evaluated the WHO Acute Respiratory Infection guideline in a large urban paediatric clinic in Egypt. METHODS: Children between 2 and 13 years of age who had a sore throat and pharyngeal erythema were enrolled in the study. Clinical, historical, and demographic information was recorded and a throat culture for group A beta-haemolytic streptococci was done. Sensitivity (% of true-positive throat cultures) and specificity (% of true-negative throat cultures) were calculated for each clinical feature. The effect of various guidelines on correct presumptive treatment for throat-culture status was calculated. FINDINGS: Of 451 children with pharyngitis, 107 (24%) had group A beta-haemolytic streptococci on throat culture. A purulent exudate was seen in 22% (99/450) of these children and this sign was 31% sensitive and 81% specific for a positive culture. The WHO Acute Respiratory Infections (ARI) guidelines, which suggest treatment for pharyngeal exudate plus enlarged and tender cervical node, were 12% sensitive and 94% specific; 13/107 children with a positive throat culture would correctly receive antibiotics and 323/344 with a negative throat culture would, correctly, not receive antibiotics. Based on our data we propose a modified guideline whereby exudate or large cervical nodes would indicate antibiotic treatment, and this guideline would be 84% sensitive and 40% specific; 90/107 children with a positive throat culture would correctly receive antibiotics and 138/344 with a negative throat culture would, correctly, not receive antibiotics. INTERPRETATION: The WHO ARI clinical guideline has a high specificity but low sensitivity that limits the unnecessary use of antibiotics, but does not treat 88% of children with a positive streptococcal throat culture who are at risk of acute rheumatic fever. A modified guideline may be more useful in this population. Prospective studies of treatment guidelines from many regions are needed to assess their use since the frequency of pharyngitis varies.

PIP: In developing country settings without access to bacterial culture and rapid diagnostic tests, the prevention of acute rheumatic fever depends on clinicians' presumptive treatment of streptococcal pharyngitis. This study evaluated the effectiveness of World Health Organization (WHO) acute respiratory infection guidelines in a large pediatric clinic (Abu Reesh Children's Hospital) in Cairo, Egypt. 451 children 2-13 years of age with sore throat and pharyngeal erythema were enrolled, 107 (24%) of whom had group A beta-hemolytic streptococci on throat culture. Purulent exudate, present in 99 (22%) of these children, was 31% sensitive and 81% specific for a positive culture. The WHO guidelines, which recommend treatment for pharyngeal exudate plus enlarged and tender cervical node, were 12% sensitive and 94% specific. Based on these guidelines, 13 of 107 children with a positive throat culture would correctly receive antibiotics and 323 of 344 with a negative culture would not receive antibiotics. A modified guideline in which exudate or large cervical nodes would indicate antibiotic treatment would be 84% sensitive and 40% specific. With this modification, 90 of 107 children with a positive throat culture would correctly receive antibiotics and 138 out of 344 with a negative culture would not receive treatment. However, additional prospective studies from other regions of Egypt are necessary before modified guidelines are implemented.