Pharmacological and epidemiological studies on the drug-sensitivity of trypanosomes isolated from a peri-urban dairy production system in Uganda.

The understanding of factors contributing to the appearance and maintenance of trypanosome drug resistance in the field is very limited,. yet this type of information would be very useful in the design of trypanosomosis control strategies. This thesis describes a study that was carried out in Mukono County, a peri-urban dairy production system near Kampala (Uganda). It had the following main objectives: a) to characterise the drug-sensitivity phenotype(s) of trypanosome field isolates collected between 1995 and 1996 from cattle; b) to determine the species and subspecies of trypanosome populations and their prevalence over the same period in cattle; c) to evaluate an isometamidium-enzyme-linked immunosorbent assay (ISMM-ELISA) using sera and use the resulting data to monitor the use of isometamidium and as a tool to indirectly assay for drug resistance; d) to establish whether the trypanosome isolates from cattle might be of zoonotic importance; and e) to analyse the factors associated with trypanocide usage and efficacy. In the first part of this study, 486 cattle from 50 farms in Mukono County were monitored for trypanosome infections over a two-year period (1995 to 1996). Eighteen trypanosome isolates were characterised in vivo for their sensitivity to isometamidium (ISMM), diminazene (DIM) and homidium (HOM). Ten of the isolates were from animals that had the highest serum ISMM concentrations (ranging from 0.3-4.5ng/ml). as determined by the ISMM-ELISA. All 18 isolates exhibited low pathogenicity in cattle and were sensitive to DIM at 3.5-mg/kg-body weight (BW) and ISMM at 0.5 mg/kg BW. In goats, two of the isolates were highly pathogenic, producing CNS involvement. All eight populations examined in goats were sensitive to DIM at 3.5 mg.kg BYV.However. two populations relapsed after treatment with ISMM at 0.5mg/kg BW. and four relapsed after treatment with HOM at 1.0 mg/kg BW. In mice. the 50% curative dose (CD50) values for the populations ranged from OJ to 1.9 mg/kg BW for DIM. from 0.02 to 0.10 rng/kg BW for ISMM and from 0.9 to 3.8 mg/kg BW for HOM. Thus. by comparison to reference drug-sensitive populations. all the isolates were highly sensitive to DIM and ISMM even though some expressed moderate levels of resistance to HOM. All the isolates contained only T brucei and/or T vivax. Twenty five percent of the T brucei populations studied were human serum resistant, indicating that cattle might be reservoir hosts for the causative agent of human sleeping sickness in this area. In the second part of this study, an improved methodology for a competitive enzyme immunoassay (CEIA) for ISMM was developed. The equilibrium method was modified to a sequential saturation procedure, because of unacceptably high intersample variation in the former. For instance. in the equilibrium procedure, the optical densities (ODs) ranged from 0.208 to 3.332, with a very high coefficient of variation (CV) of 94.8%, in adult cattle. Using the sequential saturation procedure, the CV for sera from 20 untreated cattle was 6 %. Four-parameter logistic calibration curves obtained using the sequential saturation method showed the concentration of isometamidium required for 50% competition to be approximately 1.0 ng/ml; half that previously reported for the equilibrium method. This shift in the calibration curve, together with the reduction in the inter-sample variance for untreated cattle. resulted in an improved lower limit of detection of the order of 0.1-0.2 ng/m!. In the third part of the study. the newlv developed ISl\lM-ELISA (sequential saturation) was used to monitor ISMM concentrations in sera from Mukono cattle. after block treatment with ISMM (Samorin": 1.0 mg/kg BW). Serum samples obtained from 474 cattle. distributed among 50 farms were analysed. For each animaL determinations were available for samples collected from up to four occasions. these being day 0 (the day of ISMM block-treatment) and three. approximately monthly, occasions thereafter. The mean serum ISMM concentrations were: at day zero (before drug administration). 0.67±1.28 ng/ml; at 30 days post-treatment (OPT), 0.67±0.60 ng/ml; at 60 OPT, 0.22±0.27 ng/ml; and by 90 OPT, below the detection limit of the assay. Mixed logistic regression analysis of mean serum concentrations for the 3 breed categories (exotics. locals and crosses) at 30, 60 and 90 OPT, revealed a higher probability of detecting ISMM in local than exotic cattle at all time points; suggesting a possible breed effect on the pharmacokinetics of isometamidium. Finally, factors affecting trypanocidal drug use and efficacy in Mukono were also examined. There were no obvious factors associated with drug use in the study area. Of the 1847 ISMM treatments given during the study, 234 infected cases (failures) were diagnosed during the post-treatment observation period. Of the 234 (failures), only 30 (7.4%) occurred between 7-90 days post-treatment, indicating the high efficacy of ISMM. In conciusion. the findings in this study provide important information in deciding the best control option for trypanosornosis in Mukono County. It is suggested that an integrated disease management strategy may be the best approach for the study area

Drug sensitivity patterns of bacterial isolates from septic post-operative wounds in a regional referral hospital in Uganda

Background: Wound infections have been a problem in the field of surgery for a long time.Advances in control of infections have not completely eradicated this problem because of development of drug resistance.Antimicrobial resistance can increase complications and costs associated with procedures and treatment. Objective: A study was carried out on drug sensitivity patterns of bacterial isolates from septic postoperative wounds in Jinja hospital, Uganda.This study was designed to determine the distribution of bacterial pathogens isolated from septic post-operative wounds and their antimicrobial susceptibility patterns. Method: Specimens of pus swabs were collected aseptically and analysed in the laboratory. Colony characteristics and Grams technique were used to differentiate the organisms. Biochemical tests were done to confirm the species of the organisms. Sensitivity testing was done on the isolates using the disk diffusion method. Results: Pathogenic bacteria were recovered from 58.5% of the specimens.The isolates were: S.aureus (45.1%), Coliforms (16.9%), Proteus mirabilis (11.3%), P.aeruginosa (9.9%), Klebsiella pneumoniae (7.0%) and Enterobacter spp (2.82%). Most of the organisms were sensitive to gentamicin, ciprofloxacin and ceftazidime.There was resistance to ampicillin, amoxycillin and chloramphenicol. Staphylococcus aureus was generally sensitive to gentamicin (87.5%), ciprofloxacin (68.7%) and methicillin (75%), but resistant to erythromycin (56.2%) and ampicillin (97%). Most of the gram-negative bacteria isolated (Coliforms, P.aeruginosa , E.coli , Proteus mirabilis , and Klebsiella pneumoniae ) were sensitive to Ciprofloxacin, Gentamicin and Ceftazidime but resistant to Ampicillin,Amoxycillin and Chloramphenicol. Methicillin-resistant Staphylococcus aureus (MRSA) strains formed 25% of this species. Pseudomonas aeruginosa was sensitive to gentamicin (87.5%) and ceftazidime (85.7%) but showed resistance to ciprofloxacin (57.2%). Some organisms e.g. S.aureus, Pseudomonas aeruginosa and Proteus mirabilis exhibited multi-drug resistance to the antibiotics tested. Conclusion: Since a high proportion of samples had positive cultures, infection control is recommended as a strategy to minimise spread of resistant organisms. It is recommended that gentamicin, ciprofloxacin and ceftazidime be used in preference to ampicillin and amoxycillin for treatment of septic wounds.There is need to develop national surveillance of antibiotic- resistant organisms. African Health Sciences Vol. 7 (3) 2007: pp. 148-15

The sensitivities to first-line antibiotic therapy of the common urinary tract bacterial infections detected in urine samples at a hospital in metropolitan Kampala (Uganda)

Background: Urinary tract infections (UTIs) are among the most common human infections. Many urinary tract bacteria are capable of expressing drug resistance. Resistant bacteria may be present from the commencement of the infection or may develop during treatment. This study focused on the problem of antibiotic resistance to the first-line drugs that were used to treat patients presenting with urinary tract infections at Rubaga hospital in Kampala, Uganda. Objectives: The objective of this study was to isolate and identify the major bacterial pathogens of symptomatic and asymptomatic UTIs among patients at Rubaga hospital. Furthermore, the study sought to determine the antimicrobial susceptibility patterns of the major bacterial isolates to the first-line drugs used to treat UTIs at Rubaga hospital. Methods: Urine samples were aseptically collected and examined microscopically and were microbiologically cultured on blood agar, nutrient agar and on MacConkey agar. The isolates obtained were then identified using standard tests and tested for antimicrobial sensitivity by the Kirby-Bauer technique. Results: The isolated pathogens included Escherichia coli (10.9%), Staphylococcus (31.9%), Streptococcus (9.2%), Klebsiella species (21.0%) and Proteus species (10.1%). 20 (16.8%) of the isolates were lactose fermenting gram-negative rods that were also indole-negative. These isolates were termed `unclassified coliforms&apos; in this study but were probably Enterobacter species. On antimicrobial susceptibility testing, all the gram-negative isolates were significantly resistant to amoxycillin, cotrimoxazole, erythromycin, and to nalidixic acid; but were susceptible to nitrofurantoin. Among the gram-negative isolates, only Klebsiella species were significantly resistant (p<0.05) to ciprofloxacin. The gram-positive cocci were susceptible to amoxycillin, ciprofloxacin, and to erythromycin but resistant to cotrimoxazole and nalidixic acid. Unlike the Staphylococcus species that were significantly resistant to nitrofurantoin, Streptococcus species were moderately susceptible to the drug. Conclusion: The common urinary tract bacteria detected in Rubaga hospital in Uganda were most sensitive to Ciprofloxacin and Nitrofurantoin

Screening of extracts of Zanthoxylum chalybeum and Warburgia ugandensis for activity against measles virus (Swartz and Edmonston strains) in vitro

A large proportion of the population in Uganda still relies on the use of plant extracts for treatment of various ailments. This study tested the claimed efficacy of some plants in the treatment of measles. In vitro antiviral assays were performed on extracts of two medicinal plants (Warburgia ugandensis and Zanthoxylum chalybeum) using measles virus (Edmonston and Swartz strains) as the test organisms. The assays performed were the neutralisation tests and the plaque reduction assays. Of the two plants Z. chalybeum had demonstrable in vitro antiviral activity in the seed extracts (titer reduction factor [TRF]: 100, for the ethanolic extract). The in vitro antiviral activity of the seed extracts was demonstrated to be due to compound 27–135D (TRF=1000), which was characterized by 1H-NMR spectroscopy as the alkaloid skimmianine. Skimmianine had minimal toxicity to VERO cell lines. The petroleum ether extracts and the ethanolic extracts of Warburgia ugandensis had no inhibitory effect on cytopathic effect (CPE) formation, especially at the maximal non-toxic dose (MNTD). The extracts of W. ugandensis were highy toxic to VERO cell lines. The TRF values for the stem bark extracts of W. ugandensis were: water extract, 10; ethanolic extract, 1; fraction 27–163D, 100., which were regarded to be too low. Seed extracts of Z.chalybeum therefore probably cure measles due to the antiviral effect of skimmianine. It is not clear how extracts of W. ugandensis produce a beneficial response in measles disease, if at all

Antibacterial and antifungal activities of extracts of Zanthoxylum chalybeum and Warburgia ugandensis, Ugandan medicinal plants

Measles is a killer disease of children in Uganda. The treatment of the disease is mainly directed at the secondary microbial infections. A large proportion of the population in Uganda still relies on the use of herbal remedies, which have been claimed to produce beneficial responses. In this study, the efficacy of Warburgia ugandensis and Zanthoxylum chalybeum against common bacteria and fungi was investigated. Bactericidal and antifungal assays were done using extracts derived from Z. chalybeum and W. ugandensis (agar well diffusion, disc diffusion and colony count assays). All extracts (ethanolic, petroleum ether and aqueous) of Z. chalybeum did not show antimicrobial activity. Phytochemical investigations of Zanthoxylum chalybeum (seed) yielded a pure crystalline alkaloid (27–135D) which was characterized as skimianine based on 1H-NMR spectroscopy and comparison with spectra of authentic samples. Skimmianine did not have antimicrobial activity in this test system. W. ugandensis water extracts elicited antibacterial activity against both Escherischia coli and Staphylococcus aureus in the agar well assay but not in the disc diffusion assay. Warburgia ugandensis water extracts and fraction 27-163D also showed antifungal activity against Candida albicans. Chromatography of extracts of Warburgia ugandensis stem bark afforded compound 49–169K, which was characterized as the sesquiterpine muzigadial (by 1H-NMR spectroscopy), which did not show antibacterial activity but had antifungal activity against C. albicans. Therefore, the claimed efficacy of W. ugandensis could be attributable to antibacterial and antifungal activity of its components. Since Z. chalybeum extracts had neither antifungal nor antibacterial activities, its mode of action is unclear from these results

Bioassay-guided studies on the cytotoxic and in vitro trypanocidal activities of a sesquiterpene (Muzigadial) derived from a Ugandan medicinal plant (Warburgia ugandensis)

Trypanosomiasis is arguably the most important disease of man and his domesticated animals in the tropics. There are few compounds available for its treatment. This has exacerbated the development of drug resistance. There is therefore urgent need to search for newer compounds to treat this important disease. Medicinal plants represent a potential source of the drugs. This paper reports a bioassay-guided study to search for possible biological activity (cytotoxic and trypanocidal) in two Ugandan medicinal plants. The methodology adopted was the so-called ‘ping-pong’ approach, involving phytochemical purification (column chromatography and preparative thin layer chromatography), alongside biological studies (cytotoxicity, antibacterial, trypanocidal and antifungal studies). Phytochemical investigations of Zanthoxylum chalybeum (seed) yielded a pure crystalline compound, 27-135D, which was characterized by 1HNMR as the alkaloid skimmianine. Studies on stem bark yielded three alkaloids 27-165A, 27-173A and 27-173B. All the above pure isolates, and the crude extracts of Z. chalybeum had neither biological activity nor cytotoxicity in the brine shrimp assay. A cytotoxic sesquiterpine, characterized as muzigadial, was isolated from W. ugandensis. It was highly toxic in the brine shrimp assay and also had in vitro trypanocidal activity against IL 3338 as well as IL1180; reference drug-resistant and drug-sensitive trypanosome strains respectively, comparable to diminazene aceturate and Geneticin (G418). Muzigadial also had antifungal activity against Candida albicans. It was concluded that the brine shrimp assay might be a useful predictor of trypanocidal activity of plant extracts and that muzigadial may be potentially valuable in the treatment of drug-resistant trypanosomosis

In-vitro antibacterial activity of selected medicinal plants from Longisa region of Bomet district, Kenya

Background: Current strategies to overcome the global problem of antimicrobial resistance include research in finding new and innovative antimicrobials from plants. This study was carried out to determine the antibacterial activity of plant extracts of Olea africana stem-bark, Psidium guajava leaves, Vernonia amygdalina leaves, Lantana camara leaves and Mangifera indica leaves which are used in folklore medicine to treat infections of microbial origin in Longisa region of Bomet District, Kenya.Methods: Methanol extracts were derived and screened. Standard cultures of Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923 were used in the study. The antibacterial tests used were the agar well diffusion assays at concentration 1gm/ml. Minimum Inhibition Concentration (MIC) was determined in the plant extract that showed some efficacy against the tested microorganisms. Gentamicin (10&mu;g) was used as a positive control.Results: The methanol extracts showed weak antibacterial activity against the study organisms compared to Gentamicin. All extractsexhibited a significant bactericidal activity against S. aureus while L. camara and V. amygdalina lacked efficacy against P.aeruginosa andE.coli. O.africana and P. guajava presented the lowest MIC against S.aureus (62.5 mg/ml and 250 mg/ml respectively P.guajava and M.indica showed analogous MICs against P.aeruginosa (250 mg/ml). P.guajava exhibited a better MIC against E.coli (500 mg/ml).Conclusions: This in-vitro study corroborated the antimicrobial activity of the selected plants used in folklore medicine. The plants could be potential sources of new antimicrobial agent.Key words: Medicinal Plant extracts, antibacterial activity, MICAfrican Health Sciences 2009; 9(S): 42-4

Preliminary observations on the species composition and distribution of indigenous wild mushrooms in the Lake Victoria basin wetlands, Musoma, Tanzania.

Harvesting of wild mushrooms in the Lake Victoria basin for household food and inter-household trade is widespread and mushrooms contribute strongly to household food security. In spite of the importance of mushrooms to household food security the spatial and temporal distribution and ecological conditions influencing mushroom growth and availability in the Lake Victoria basin are yet to be documented adequately to enable development of plans for their conservation. The objective of this study was to document the composition, seasonal and spatial distribution of the mushrooms of the Lake Victoria basin wetlands and their habitats. Preliminary surveys identified a total of nine species most of which are of the genus Termitomyces. Generally most of the mushrooms were associated with termite mounds thus growing on clay soils and soils associated with low organic matter. Some species grow solely on termite mounds while others can grow a distance from a termite mound but associated with underground termite nests. Majority of the mushrooms appear during the rain season and are equally available during the short and long rains. This suggests that most species will grow well throughout the year whenever moisture level in the substrate is adequate irrespective of the season. Some of the species especially the Polypores (Ganoderma sp.) grow on dead wood as well as on living trees, infecting living trees through wounds. Most of the species grow in acidic (pH 6.5) substrates with a pH range between 5 and 6.8 though one species (Termitomyces clypeatus) was observed to grow on slightly alkaline conditions. Generally the substrate for most species had low organic carbon ranging from 3% to slightly above 4%. More detailed study of the ecology of the most important mushrooms in the Lake Victoria basin wetlands is important as a basis for their management and domestication. TJFNC Vol. 76 2007: pp. 80-8

Ethno-pharmacological practices in management of livestock helminthes by pastoral communities in the drylands of Uganda. Livestock Research for Rural Development

Abstract A two stage sampling ethno-pharmacological study was carried out with agro-pastoralists in Nakasongola district involving two sub-counties namely; Nabiswera and Nakitoma. Participatory methods were used to establish a livestock disease inventory, ethno-diagnosis, medicinal plants used and implication for livestock-based livelihoods. Fourteen focus groups discussion comprising of 198 persons and 32 key informant interviews were conducted. Trypanosomosis (20.9%), East cost fever (15.5%) and helminthosis (12.8%) were found to be the most prevalent of the twenty five diseases affecting different livestock species in the area. Thirty seven plants species belonging to 28 genera and 24 families were reported as traditional treatments against helminthosis. The frequently used plant parts were leaves(54.1%) and roots (29.7%). Cold aqueous extraction (pounding and adding water) (81.1%) was the main method of preparation of ethno-veterinary remedies with oral drenching as the main route of administration. About 65% of population used combination of traditional and conventional veterinary medicine, 22% used only conventional veterinary medicines, while 13% of the farmers used traditional medicine. Accuracy of ethno-diagnosis compared well with conventional veterinary medicine diagnosis although the causes of the diseases were not well understood by the respondents. Medicinal plants were found to be an important input in livestock production although their efficacy, active molecules and safety is not known thus there was urgent need of scientific studies into these research gaps