Two new methods for the determination of hydraulic fracture apertures in fractured-rock aquifers

Fracture apertures play a significant role in groundwater systems. For proper groundwater quantity and contamination management, fractures have to be properly characterised. However, due to their complexity, fracture characterisation is one of the main challenges for hydrogeologists all over the world. This is particularly important in South Africa, where aquifers are predominantly fractured. Two new methods have been developed to determine inclined and horizontal fracture apertures in fractured-rock aquifers. The first is a water-balance method, the slug-tracer (ST) test:. The slug-tracer (ST) test[b = (r2 / R2) ƒ¢ h]and the second is a tracer-detection method, comprising the NAPL entry pressure (NEP) test and the NAPL injection pressure (NIP) test:. The NAPL entry pressure (NEP) test[b = (r ƒÏ g h)]. The NAPL injection pressure (NIP) test[b = (ƒÏ g V/ 2 ƒÎ r)] and [b = (M g) / m]These mathematical formulations were developed from laboratory experimentation using transparent Perspex parallel plate physical models and 27 apertures of 0.008 mm to 6 mm, created by using aluminium foil and thickness gauges between 20 mm thick clamped Perspex plates. The ST test uses a slug to which is added NaCl as tracer (50 mg to 300 mg/.). An EC meter is used to detect breakthrough in the observation boreholes.The NEP test uses an NAPL (sunflower oil) hydraulic head and transducers to determine the entry pressure. Using these mathematical formulae, fracture apertures are then determined for horizontal and inclined apertures. The NIP test uses the entry pressure (by injection), recorded by transducers of an NAPL (sunflower oil) and its volume or mass to determine the fracture aperture for horizontal and inclined fractures. Results from smooth and rough (buffed to 10 x 20 ƒÊ) fracture surfaces gave accuracies of 96 to 98% for aperture determinations of 26 apertures from 0.04 to 6 mm

The trigger-tube: A new apparatus and method for mixing solutes for injection tests in boreholes

The trigger-tube apparatus and method was developed for mixing solutes and tracers for injection tests. The apparatus is a cap-trigger tube segment and the technique mixes solutes in boreholes in 2 min. Trigger-tube with solute/tracer is introduced into the well, the trigger is released, the tube is withdrawn and the solute/tracer mixes with well water instantaneouslyto give a homogeneous mixture. Field tests using this method and apparatus for point dilution tests gave a Darcy velocity of 4.06 m/d, seepage velocity of 122.89 m/d and effective porosity of 0.33. Natural gradient tests gave a Darcy velocity of 4.06 m/d and natural velocity of 123 m/d, using tracer, for the same fracture at 21 m in borehole UO5, University of the Free State campus test site. The apparatus enables a comparatively shorter time for carrying out SWIW tests than is possible using the pump mixing method. Field tests gave results of 13 min for the trigger-tube method and 25 min for the pump mixing method, for a point dilution test using NaCl as a conservative tracer. The trigger-tube apparatus can be used for any borehole test that requires the introduction of a homogenous mixture

Water sources as reservoirs of Vibrio choleraeO1 and non-O1 strains in Bepanda, Douala (Cameroon): relationship between isolation and physico-chemical factors

BACKGROUND: Cholera has been endemic in Douala since 1971. Most outbreaks start from Bepanda, an overcrowded neighbourhood with poor hygiene and sanitary conditions. We investigated water sources in Bepanda as reservoirs of Vibrio cholerae, the causative agent of cholera, determined its antibiotic susceptibility and some physico-chemical characteristics that could maintain the endemicity of this organism in Bepanda. METHODS: Three hundred and eighteen water samples collected from 45 wells, 8 taps and 1 stream from February to July 2009 were analyzed for V. cholerae using standard methods. Isolates were characterized morphologically, biochemically and serologically. The disc diffusion technique was employed to investigate antibiotic susceptibility. Differences in prevalence of organism between seasons were analysed. Correlation strength and direction of association between physico-chemical parameters and occurrence of V. cholerae was analyzed using the Kendall tau_b non-parametric correlation. This was further confirmed with the forward-stepwise binary logistic regression. RESULTS: Eighty-seven (27.4%) samples were positive for V. cholerae. Isolation was highest from wells. The organism was isolated in the rainy season and dry season but the frequency of isolation was significantly higher (χ(2) = 7.009, df = 1, P = 0.008) in the rainy season. Of the 96 confirmed V. cholerae isolates, 32 (33.3%) belonged to serogroup O1 and 64 (66.6%) were serogroup non-O1/non-O139. Isolates from tap (municipal water) were non-O1/non-O139 strains. Salinity had a significant positive correlation with isolation in the dry season (+0.267, P = 0.015) and rainy season (+0.223, P = 0.028). The forward-stepwise method of binary logistic regression indicated that as pH (Wald = 11.753, df = 1), P = 0.001) increased, odds of isolation of V. cholerae also increased (B = 1.297, S.E = 0.378, Exp(B) = 3.657). All isolates were sensitive to ciprofloxacin and ofloxacin. Multi-drug resistance was predominant among the non-O1/non-O139 isolates. CONCLUSION: V. cholerae was found in wells and stream in both seasons. Cholera will continue to be a health threat in Bepanda if intervention measures to prevent outbreak are not implemented. Continuous monitoring of water sources in this and other cholera high-risk areas in Cameroon is necessary, for a better preparedness and control of cholera. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2334-14-421) contains supplementary material, which is available to authorized users

Phenotypic Characterization of Salmonella Typhimurium Isolates from Food-animals and Abattoir Drains in Buea, Cameroon

Salmonella spp. have been extensively incriminated worldwide as common causes of bacterial gastroenteritis in humans, with food-animals serving as important reservoirs. The study was aimed at investigating cattle and pigs slaughtered in Buea as reservoirs of Salmonella Typhimurium and the susceptibility of isolates to antibiotics. In total, 230 specimens (comprising 50 each from the rectum, ileum, and gall bladder of cattle; and 10 each from same anatomical sites of pigs and 50 from abattoir drains) were analyzed for Salmonella using the standard microbiological, biochemical and serological techniques. Antibiotic susceptibility of the isolates was determined by the Kirby-Bauer disc-diffusion test. The isolates were characterized into biotypes using the API 20E kit, and results were analyzed using the chi-square test. Seventy-five (32.6%) of the 230 specimens were positive for S. Typhimurium, with pigs and abattoir drains presenting the highest level of isolation (40%). Biochemical typing grouped the isolates into five biotypes. Biotype I was the most prevalent (30.6%) while biotype IV was the least prevalent (9.3%) and was absent in samples from pigs. Antibio-tic susceptibility studies revealed 14 antibiotypes based on antibiotics used in the study. The predominant antibiotype AMXR DOXRCEFR was recorded in 13 (17.3%) of the isolates. Multidrug resistance (to four or more antibiotics) was recorded in 50.7% (38/75) of the isolates. The most active drugs were ciprofloxacin (98.6%), ofloxacin (93.3%), amikacin (90.6%), and gentamicin (84%). All the isolates (100%) were resistant to tetracycline and ampicillin. Cattle and pigs were found to be reservoirs of S. Typhimurium in the environment of Buea, Cameroon, implying that foods from these sources, if not properly handled, could serve as vehicles for its transmission to humans

Knowledge, Attitudes and Practices Among Adult Malaria Patients Co-Infected with Opportunistic Intestinal Coccidian Parasites in Fundong Health District, Northwest, Cameroon: A Cross Section Study Design

Introduction: Malaria and intestinal coccidian parasitic co-infections, are becoming a public health emergency affecting millions of people around the world. They are among the leading cause of socio-economic problems, long suffering and death especially in developing countries like Cameroon. Introducing new appropriate preventive and control measures to the population requires thorough assessment of community and patient-based knowledge, attitude and preventive practices towards malaria and pathogenic intestinal coccidian parasites is crucial. Our study aimed to describe knowledge, attitudes, and practices and the risk factors among adult malaria patients co-infected with intestinal parasitic infections in the Fundong Health District, a locality in the Northwest Region of Cameroon. Methods: This was a cross-sectional study carried out between February and December, 2022 involving sixteen (16) health facilities in Fundong Health district. A total number of 330 patients participated in the study. Normal saline wet mount and formol-ether concentration techniques were employed in coccidian parasitic detection. Blood samples were subjected to Giemsa stained and viewed microscopically to detect the Plasmodium parasites. Pretested structured questionnaires were administered to collect information on patient’s socio-demographic factors and determine patients’ knowledge, attitudes and practices towards malaria and intestinal coccidian parasites, as well as their prevention and control. The Pearson’s Chi-Square (χ2) and Student T-test were performed a part of the statistical analysis to check for associations between malaria, infection and between malaria-coccidian co-infection and demographic factors. Statistical significance was set a P-value<0.05. Results: Participants main sources of information on malaria were: Television (TV) and radio 111/330 (34%), community health workers 109/330 (33%), and Hospitals (37%). Participants had good knowledge of mosquito bite as the malaria transmission route, 296/330 (90%), night time is the frequent biting time for the mosquito 296/330(90%), dark corners 229 (69%) and dirty areas 175(53%) as mosquito resting places. Knowledge score was also good on cleaning of the house surroundings, 281/330(85%), clearing the bushes 180/330(55%), poor knowledge score on drainage of stagnant water113/330 (34%) as ways to prevent the mosquito from multiplying. Participants had good knowledge of insecticide treated bed nets 295/330 (89%) as the best way to prevent mosquito bites. However, participants also expressed poor knowledge on edges of the river or streams 7(20%), and animal shed 20/330 (6%) as mosquito hiding places, and Plasmodium specie as malaria causative agent 8/330 (2%) (P-value=0.011). Poor scores were recorded on knowledge of opportunistic intestinal coccidian parasites (19.4%) (P=0.427), and was significantly low on unsafe water (47.2%) (P-value=0.036) as possible transmission routes for coccidian parasites. The knowledge score was also low on the at-risk population for malaria and intestinal coccidian infection (31.9%) P-value=0.009. Participants who had poor knowledge about coccidian transmission routes were less likely to drink from protected water source with an odds of 0.713(95% CI: 0.297-1.711) P value=0.449, compared to those who were more knowledgeable and who were 2.981(95% CI: 1.367-6.115) P value=0.005, more likely to use protected source of drinking water. Participants who had hand washing facility in the household were 3.488 (1.760-6.912) value=0.001 times more likely have better knowledge of coccidian transmission routes compared to those who did not have 0.748 (95% CI: 0.406-1.376) P value=0.350. Poor knowledge score of poor hygiene as major cause of coccidian infection significantly associated with poor practice score of sometime or not at all disinfecting animal shed to prevent coccidian infection among study participants (P =0.039). Conclusion: The overall knowledge scores, attitude and practices level of participants towards malaria and opportunistic intestinal coccidian parasites were relatively good. A significant proportion of the participants still have misconceptions about cause, modes of transmission and practices towards malaria and coccidian prevention methods. A combined health education programmes for malaria and intestinal coccidian parasites aimed at raising community awareness needs to be evidence based and requires innovative approaches, to address the gaps identified in the study

Risk factors for wound infection in health care facilities in Buea, Cameroon: aerobic bacterial pathogens and antibiogram of isolates

Introduction: Wound infection is a significant clinical challenge in hospitals in developing countries  where proper healthcare delivery is hampered by limited resources. This study investigated the antibiotic susceptibility pattern of bacteria causing wound infection and risk factors for infection among hospitalized patients in Buea, Cameroon, to generate findings which could drive reformation of policies on infection control.Methods: Aerobic bacteria were isolated from 212 swabs collected from patients with clinically  diagnosed infected wounds. Risk factors for wound infection were investigated. Antibiotic susceptibility of isolates was determined by disk diffusion technique. The Chi-square test was employed to determine significant differences in isolation and distribution of organisms in various specimens. Differences were considered significant at P < 0.05.Results: Twelve bacteria species were isolated from 169 (79.7%) specimens. Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae, the predominant isolates in all wound types  exhibited a high preponderance of multidrug resistant strains. High rate of infection was attributed tolack of constant water supply and breakdown of sterilization equipment during the study period. Highest diversity of pathogens occurred in open wounds. There were no significant differences (P>0.05) in isolation of pathogens with respect to age, gender and wound type. Co-existing morbidity increased risk of wound infection. Isolates were susceptible to fluoroquinolones and resistant to oxacillin. Conclusion: Wound infection with resistant bacteria constitutes a significant cause of morbidity in the study area. Findings reiterate the need to strengthen infection control and drug dispensing policies, and greater  collaboration between microbiologists and medical practioners to stem the spread of resistant bacteria.Key words: Wound infection; antibiotic susceptibility; co-morbidity, bacterial pathogens, Cameroo

In vitro anti-Helicobacter pylori activity of Lycopodium cernuum (Linn) Pic. Serm

Helicobacter pylori, a gram negative microaerophilic bacterium is a major etiological agent in duodenal, peptic and gastric ulcers. In this study, gastric biopsy samples were obtained from patients presentingwith gastroduodenal complications. H. pylori was isolated from the specimens following standard microbiology procedures, and isolates subjected to pure fractions of Lycopodium cernuum extracts forantimicrobial assays. Extracts were fractionated by partition chromatography with solvents of increasing polarity to obtain pure fractions. The disk diffusion method was used to determine thesusceptibility of 15 strains of H. pylori to the fractions. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the most active fraction was also determined by thebroth dilution method. Results were analyzed by the Fisher’s exact test. All the fractions tested demonstrated antimicrobial activity with zone diameters of inhibition between 0 - 30 mm. Of the 5 fractions obtained, the hexane (Hex) fraction was the most active. The lowest MIC and MBC recorded for the hexane (Hex) fraction were 0.016 and 0.125 mg/mL, respectively. There was no statistically significant difference (P>0.05) in the potency of the fraction on the different bacterial strains tested, both for the MIC and MBC. It is concluded that this plant may contain compounds with therapeutic activity, which may be found in the Hex fraction (100%)

Current antibiotic susceptibility profile of the bacteria associated with Surgical wound infections in the Buea health district in Cameroon

Background: Most surgical wounds seen in clinical practice in the Buea Health District, Cameroon are infected prior to arrival or while they are in the hospital. Sometimes the infection necessitates a combination of local wound site measures and systemic antibiotherapy to properly manage the patient.Objective: To identify the current antibiotic susceptibility profile of the common germs that cause surgical wound infections in the Buea Health District of Cameroon.Methods: A total of 2120 specimens comprising swabs from burns, ulcers, open or post-operative wounds were collected from hospitalized patients attending health institutions in Buea. The samples were collected from different anatomic sites of the patients. Cultures were effected from the specimens and bacteria isolated from infected wounds using standard microbiological techniques. Antibiotic susceptibility of the different isolates was determined.Results: Majority (79.8%) of the wounds were infected with pathogenic bacteria. The germs globally showed multi resistant patterns to commonly used antibiotics in the study area, especially to co-trimoxazol, doxycycline, chloramphemicol, ampicilline and aztreonam. However appreciable sensitivity was noted to ofloxacillin, perflacin, and ceftriazone.Conclusion: This study has revealed ofloxacin as the only antibiotic to which all the isolated bacteria from infected wounds were sensitive in the study area.Keywords: Wound infection, Antibiotic susceptibility profile, Buea Health District, Cameroo

Phenotypic Characterization of Salmonella Typhimurium Isolates from Food-animals and Abattoir Drains in Buea, Cameroon

Salmonella spp. have been extensively incriminated worldwide as common causes of bacterial gastroenteritis in humans, with food-animals serving as important reservoirs. The study was aimed at investigating cattle and pigs slaughtered in Buea as reservoirs of Salmonella Typhimurium and the susceptibility of isolates to antibiotics. In total, 230 specimens (comprising 50 each from the rectum, ileum, and gall bladder of cattle; and 10 each from same anatomical sites of pigs and 50 from abattoir drains) were analyzed for Salmonella using the standard microbiological, biochemical and serological techniques. Antibiotic susceptibility of the isolates was determined by the Kirby-Bauer disc-diffusion test. The isolates were characterized into biotypes using the API 20E kit, and results were analyzed using the chi-square test. Seventy-five (32.6%) of the 230 specimens were positive for S. Typhimurium, with pigs and abattoir drains presenting the highest level of isolation (40%). Biochemical typing grouped the isolates into five biotypes. Biotype I was the most prevalent (30.6%) while biotype IV was the least prevalent (9.3%) and was absent in samples from pigs. Antibiotic susceptibility studies revealed 14 antibiotypes based on antibiotics used in the study. The predominant antibiotype AMXR DOXRCEFR was recorded in 13 (17.3%) of the isolates. Multidrug resistance (to four or more antibiotics) was recorded in 50.7% (38/75) of the isolates. The most active drugs were ciprofloxacin (98.6%), ofloxacin (93.3%), amikacin (90.6%), and gentamicin (84%). All the isolates (100%) were resistant to tetracycline and ampicillin. Cattle and pigs were found to be reservoirs of S. Typhimurium in the environment of Buea, Cameroon, implying that foods from these sources, if not properly handled, could serve as vehicles for its transmission to humans