Pattern and microbiological characteristics of diabetic foot ulcers in a Nigerian tertiary hospital

Purpose: To determine the pattern and bacteriological characteristics of diabetic foot ulcers in patients attending a tertiary health care facility.Method: 160 Patients with Diabetes Mellitus foot syndrome were recruited, out of which 52 had diabetic foot ulcers. Relevant clinical, biochemical, and microbiological evaluations were carried out on the subjects. Data analysis was done using SPSS ver- sion 20. p value was set at <0.05.Results: 52 (32.5%) out of 160 subjects with Diabetes Mellitus Foot Syndrome (DMFS) had diabetic foot ulcers. Poor glycaemic control (mean HbA1c = 9.2 (2.7) %), and abuse of antibiotics (76.9%) characterized the subjects. Foot ulcers mainly involved the right lower limb and followed spontaneous blister formation (50%). Microbiological culture pattern was polymicrobial (71.2%); predominantly anaerobic organisms (53.3%). Gram positive and negative aerobic isolates yielded high sensitivity to common quinolones (76% - 87.8%). The gram positive and negative anaerobic isolates were highly sensitive to Clindamycin and Metroni- dazole respectively (80.2% - 97.8%). High sensitivity (>80%) yield for gram negative anaerobes was recorded for Imipinem and Ampicillin/Sulbactam.Conclusion: Diabetic foot ulcers (DFU) contribute about one-third of DMFS. The bacteriological isolates from these ulcers are mainly polymicrobial with high sensitivity to common antibiotics. The need for appropriate use of antibiotics should be advocated among the patients.Keywords: Diabetes mellitus, antibiotic sensitivity, Nigeria

Knowledge and practice of female secondary school students aboutHIVand sexually transmitted infections in Enugu, South East Nigeria

Purpose: The purpose of this study was to determine the knowledge and practice of female secondary school students to sexually transmitted infections in Enugu, South East Nigeria.These could pose as barriers to effective sexual education and impair case management within the community.Methods: This study was cross-sectional and descriptive in design using a self- administered custom designed multiple choice questionnaire with sections on general information on sexually transmitted infections, awareness and perception of such infections. Ethical clearance and informed consent were obtained.Results: There were 183 respondents with a mean age of 15.9 ± 1.3 years, all female.There was a high level of awareness of HIV (97.8%) and STIs (94.5%).While 74.3% had correct knowledge of modes of transmission,60.7% incorrectly identified casual contact as modes of transmission of HIV. Only 59% correctly identified all the HIV prevention methods tested, while 74.9% practiced all modes of prevention. The median aggregate score for knowledge of transmission and prevention was 72.2%, while it was 62.5% for good prevention practice. The older students were more likely to be sexually active.Conclusion: Female secondary school students in Enugu had a high level of awareness for sexually transmitted infections, especially for HIV. However, in-depth knowledge regarding mode of transmission and prevention was sub-optimal.There is a need to strengthen public and school based sexual health education in Nigeria.Keywords: Sexually transmitted infections, knowledge, female students, Nigeri

Pattern and microbiological characteristics of diabetic foot ulcers in a Nigerian tertiary hospital

Purpose: To determine the pattern and bacteriological characteristics of diabetic foot ulcers in patients attending a tertiary health care facility. Method: 160 Patients with Diabetes Mellitus foot syndrome were recruited, out of which 52 had diabetic foot ulcers. Relevant clinical, biochemical, and microbiological evaluations were carried out on the subjects. Data analysis was done using SPSS version 20. p value was set at <0.05. Results: 52 (32.5%) out of 160 subjects with Diabetes Mellitus Foot Syndrome (DMFS) had diabetic foot ulcers. Poor glycaemic control (mean HbA1c = 9.2 (2.7) %), and abuse of antibiotics (76.9%) characterized the subjects. Foot ulcers mainly involved the right lower limb and followed spontaneous blister formation (50%). Microbiological culture pattern was polymicrobial (71.2%); predominantly anaerobic organisms (53.3%). Gram positive and negative aerobic isolates yielded high sensitivity to common quinolones (76% - 87.8%). The gram positive and negative anaerobic isolates were highly sensitive to Clindamycin and Metronidazole respectively (80.2% - 97.8%). High sensitivity (>80%) yield for gram negative anaerobes was recorded for Imipinem and Ampicillin/Sulbactam. Conclusion: Diabetic foot ulcers (DFU) contribute about one-third of DMFS. The bacteriological isolates from these ulcers are mainly polymicrobial with high sensitivity to common antibiotics. The need for appropriate use of antibiotics should be advocated among the patients. DOI: https://dx.doi.org/10.4314/ahs.v19i1.37 Cite as: Anyim O, Okafor C, Young E, Obumneme-Anyim I, C N. Pattern and microbiological characteristics of diabetic foot ulcers in a Nigerian tertiary hospital. Afri Health Sci. 2019;19(1). 1617-1627. https://dx.doi.org/10.4314/ahs.v19i1.3

Nitrogen Oxides as a by-product of Ammonia/Hydrogen combustion regimes

Alternative fuels are under scrutiny for mitigating carbon dioxide emissions. One of these alternatives is ammonia, which can be produced from waste sources, renewable energy and even nuclear power with potentially zero carbon emissions over most of its life cycle. The difficulties of pure ammonia combustion, partially due to its low flame speed and flammability, can be addressed by doping ammonia mixtures with hydrogen, which increases the reactivity of these blends and allows combustion features similar to those of some fossil fuels. However, NOx emissions are still a problem when burning ammonia, with some circumstances where emissions are even worse than with fossil-based systems. This is a consequence of the considerable formation of N2O, a greenhouse gas that is known to possess up to 300 times the Global Warming Potential (GWP) of carbon dioxide, making these regimes unsuitable for the purpose of fuel replacement to combat climate change. Therefore, this work shows bespoke results for unburned NH3 and NOx emissions, specifically NO, NO2 and N2O, at various conditions of operation whilst employing ammonia-hydrogen blends in a tangential swirl burner representative of industrial gas turbines. The results show a good compromise of NOx emissions at the near 1.05 - 1.2 equivalence ratio, with further understanding behind the chemistry that precludes the formation/consumption of these unwanted emissions for full deployment of ammonia-based energy systems

Numerical and experimental study of product gas characteristics in premixed ammonia/methane/air laminar flames stabilised in a stagnation flow

The adoption of ammonia/hydrocarbon fuel blends can be viewed as an intermediate step towards a hydrogen economy, hence the characterization of methane/ammonia flame product gas trends is essential for designing combustors for a broader range of low-carbon fuel blends while fulfilling strict NOx requirements. This paper describes the product gas content of laminar premixed ammonia/methane flames for a range of equivalence ratios and ammonia heat ratios ranging from 10% to 60%, using a strain stabilized burner at atmospheric pressure and room temperature. The optimal condition to reduce NOx emissions while maintaining below 100 ppm of unburnt NH3 emissions was found to be at equivalence ratio of 1.20 for higher ammonia ratios, moving incrementally closer over 1.35 as the methane fuel content was increased. Meanwhile, the highest measured NO values were ∼6,950 ppm at an equivalence ratio of 0.9, peaking at heat ratios of 30% to 40% at this equivalence ratio. Detailed reaction mechanisms were evaluated against the experimental data and rate constants of NO production/consumption steps featuring both NH and HNO intermediates and thermal NOx reactions were updated for Okafor's mechanism. Changes in reaction rate constants improved the mechanism accuracy for NO emissions in lean to stoichiometric flames. Meanwhile, in the rich region, modelled NO values were less responsive to changes in reaction constants, suggesting the need for an alternative approach to improve NO predictions for rich, high methane content flames. However, N2O performance in the rich region could be improved, highlighting the significance of the HNO+CONH+CO2 reaction

Nitrogen oxide emissions analyses in ammonia/hydrogen/air premixed swirling flames

Ammonia/hydrogen fuel blends have gathered interest as a promising solution for the development of a hydrogen economy, with advantages in storage cost or combustion properties compared to pure hydrogen or pure ammonia, respectively. In that pursuit, the present work reports the trends of nitrogen oxide emissions for ammonia/hydrogen blends at atmospheric conditions. NO, NO2 and N2O productions/consumptions are approached in detail in combination with unburnt ammonia. All cases are measured in a turbulent, swirl-stabilised flame configuration across hydrogen fuel fractions from 0% to 25% and equivalence ratios from 0.55 to 1.30. A detailed chemistry analysis was conducted using a chemical reactor network (CRN) employing detailed reaction chemistry. The results show that NO and NO2 emissions peaks around Φ = 0.8, whereas considerable amount of N2O is generated at very lean conditions, Φ ≤ 0.65. Availability of OH radicals and O/H pools in the flames contribute towards fuel NO formation, which in turn produces NO2 and N2O. However, very lean conditions lead to lower temperatures that ensure the survival of N2O. The results identified Φ = 1.05–1.2 as the optimum equivalence ratios for reduced NOX emissions in ammonia/hydrogen blends, with further understanding of the flame chemistry responsible behind these emissions

N2O production characteristics of strain stabilized premixed laminar ammonia/hydrogen/air premixed flames in lean conditions

Product gas characteristics of ammonia/hydrogen/air laminar premixed flames stabilized in stagnation flows were experimentally and numerically studied. Although the maximum value of NO mole fraction increased compared with pure ammonia/air flames, the trade-off relationship between NO and unburnt NH3 were also observed. In addition, N2O production for very lean conditions were observed. To clarify the N2O production mechanism in detail, numerical simulation modelling was employed using CHEMKIN software. Sensitivity analysis suggested that the reactions of (R58) NH+NO = N2O+H, (R105) N2O+H = N2+OH, and (R106) N2O(+M) = N2+O(+M) play an important role in N2O production. Product gas characteristics of N2O were numerically investigated for various stagnation plane temperatures and the equivalence ratios. The reaction rate of R106 decreases for low stagnation plane temperature cases and small equivalence ratios. It was considered that the decrease in the reaction rate of R106 decreased the reduction rate of N2O to N2, and thus large amount of N2O were detected. Also, the N2O amount decreased when the stagnation plane temperatures were sufficiently high. This also suggested that the N2O production may be restricted by a decrease in the heat loss in an ammonia-fueled combustor

Study on N2O production mechanisms of lean ammonia/hydrogen/air premixed laminar flames

Application of ammonia as fuel is a potential candidate to achieve carbon neutrality. As laminar burning velocity of ammonia is slow, hydrogen addition is also considered to improve combustion characteristics with no carbon emission. In this study, we experimentally investigated product gas characteristics of strain stabilized ammonia/hydrogen/air premixed laminar flames under atmospheric pressure for various equivalence ratios. In a lean condition, large amount of N2O production was observed. To clarify N2O production mechanisms, numerical simulations were conducted using a reaction mechanism developed by Gotama et al. In the Gotama reaction mechanism, major N2O production path was NH+NO=N2O+H and major N2O consumption paths were N2O+H=N2+OH and N2O(+M)=N2+O(+M). It was clarified that a decrease in N2O consumption via N2O(+M)=N2+O(+M) increases N2O emission for lean and strained conditions