NRU :: Browsing by Author "Nakavuma, Jesca L."

Browsing by Author "Nakavuma, Jesca L."

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Awareness of mycotoxins and occurrence of aflatoxins in poultry feeds and feed ingredients in selected regions of Uganda
(International Journal of Food Contamination, 2020) Nakavuma, Jesca L.; Kirabo, Angella; Bogere, Paul; Nabulime, Margaret M.; Kaaya, Archileo N.; Gnonlonfin, Benoit
Background: Aflatoxins are a category of mycotoxins produced by certain molds naturally occurring as food and feed contaminants with toxic effects to both animals and humans. In Uganda, previous studies on aflatoxins mainly considered human foods, but scarce information exists for animal feeds. The study aimed at establishing the current status of aflatoxins contamination of poultry feeds, level of awareness and the existing technological challenges and innovations to mycotoxin control in Uganda. Method: Mycotoxin awareness, predisposing factors and existing strategies for managing mycotoxin contamination were investigated through focus group discussions and questionnaires with selected processors and farmers. Poultry feed and feed ingredient samples were collected and analyzed for total aflatoxins using VICAM Fluorimeter procedure for foods and animal feeds. Results: Majority of the farmers and processors (> 50%) had limited knowledge about aflatoxins; contamination predisposing factors; dangers to animals and humans; and mitigation strategies. The study further revealed poor feed and feed ingredients handling and storage practices that predispose to mold/aflatoxin contamination. Forty feed samples from feed processing plants had aflatoxins in the range 7.5 ± 0.71 to 393.5 ± 19.09 parts per billion (ppb) with only twelve samples being within the generally acceptable limits of 20 ppb as recommended by the Food and Agricultural Organisation and the United States Federal Department of Agriculture. Additionally, all 27 feed samples obtained from the farmers had aflatoxins in the range of 19.0 ± 1.41 to 188.5 ± 2.12 ppb and were above the acceptable limit. Generally, broiler feeds were the most contaminated with aflatoxins. Of the feed ingredients tested, silver fish (Rastrineobola argentea, locally known as “mukene”) had the least concentration (8.7 ± 3.18 ppb) of aflatoxins while maize bran had the highest level of contamination, 103.3 ± 22.98 ppb.
Bacteriophage activity against and characterisation of avian pathogenic Escherichia coli isolated from colibacillosis cases in Uganda
(PLoS ONE, 2020) Kazibwe, George; Katami, Phionah; Alinaitwe, Ruth; Alafi, Stephen; Nanteza, Ann; Nakavuma, Jesca L.
Avian Pathogenic Escherichia coli (APEC) cause colibacillosis leading to significant economic losses in the poultry industry. This laboratory-based study aimed at establishing stocks of avian pathogenic Escherichia coli lytic bacteriophages, for future development of cocktail products for colibacillosis management. The study determined the antibiotic susceptibility; phylogenetic categories, occurrence of selected serotypes and virulence genes among Escherichia coli stock isolates from chicken colibacillosis cases; and evaluated bacteriophage activity against the bacteria. Escherichia coli characterization was done through phenotypic and multiplex PCR methods. Bacteriophage isolation and preliminary characterization was achieved using the spot assay and overlay plating techniques. Fifty-six (56) isolates were phenotypically confirmed as E. coli and all exhibited resistance to at least one antimicrobial agent; while multi-drug resistance (at least three drugs) was encountered in 50 (89.3%) isolates. The APEC isolates mainly belonged to phylogroups A and D, representing 44.6% and 39.3%, respectively; whereas serotypes O1, O2 and O78 were not detected. Of the 56 isolates, 69.6% harbored at least one virulence gene, while 50% had at least four virulence genes; hence confirmed as APEC. Virulence genes, ompT and iutA were the most frequent in 33 (58.9%) and 32 (57.1%) isolates respectively; while iroN least occurred in 23 (41.1%) isolates. Seven lytic bacteriophages were isolated and their host range, at 1×108 PFU/ml, varied from 1.8% to 17.9% of the 56 APEC isolates, while the combined lytic spectrum was 25%. Phage stability was negatively affected by increasing temperatures with both UPEC04 and UPEC10 phages being undetectable at 70˚C; whereas activity was detected between pH 2 and 12. The high occurrence of APEC isolates resistant against the commonly used antibiotics supports the need for alternative strategies of bacterial infections control in poultry. The low host range exhibited by the phages necessitates search for more candidates before in-depth phage characterization and application.
Carbapenem Resistance Profiles of Pathogenic Escherichia coli in Uganda
(2020) Ssekatawa, Kenneth; Byarugaba, Denis K.; Nakavuma, Jesca L.; Kato, Charles D.; Ejobi, Francis; Tweyongyere, Robert; Wampande, Eddie M.
Escherichia coli has been implicated as one of the main etiological agents of diarrhea, urinary tract infections, meningitis and septicemia worldwide. The ability to cause diseases is potentiated by presence of virulence factors. The virulence factors influence the capacity of E. coli to infect and colonize different body systems. Thus, pathogenic E. coli are grouped into DEC strains that are mainly clustered in phylogenetic group B1 and A; ExPEC belonging to A, B2 and D. Coexistence of virulence and beta-lactamase encoding genes complicates treatment outcomes. Therefore, this study aimed at presenting the CR profiles among pathogenic E. coli. Methods: This was a retrospective cross-sectional study involving use of archived E. coli clinical isolates collected in 2019 from four Ugandan tertiary hospitals. The isolates were subjected to antibiotics sensitivity assays to determine phenotypic resistance. Four sets of multiplex PCR were performed to detect CR genes, DEC pathotypes virulent genes, ExPEC PAI and the E. coli phylogenetic groups. Results: Antibiotic susceptibility revealed that all the 421 E. coli isolates used were MDR as they exhibited 100% resistance to more than one of the first-line antibiotics. The study registered phenotypic and genotypic CR prevalence of 22.8% and 33.0% respectively. The most predominant gene was blaOXA-48 with genotypic frequency of 33.0%, then blaVIM(21.0%), blaIMP(16.5%), blaKPC(14.8%) and blaNDM(14.8%). Spearman’s correlation revealed that presence of CR genes was highly associated with phenotypic resistance. Furthermore, of 421 MDR E. coli isolates, 19.7% harboured DEC virulent genes, where EPEC recorded significantly higher prevalence (10.8%) followed by S-ETEC(3.1%), STEC(2.9%), EIEC (2.0%) and L-ETEC(2.0%). Genetic analysis characterized 46.1% of the isolates as ExPEC and only PAI IV536(33.0%) and PAI IICFT073(13.1%) were detected. Phylogenetic group B2 was predominantly detected (41.1%), followed by A(30.2%), B1(21.6%), and D(7.1%). Furthermore, 38.6% and 23.1% of the DEC and ExPEC respectively expressed phenotypic resistance. Conclusion: Our results exhibited significant level of CR carriage among the MDR DEC and ExPEC clinical isolates belonging to phylogenetic groups B1 and B2 respectively. Virulence and CR genetic factors are mainly located on mobile elements. Thus, constitutes a great threat to the healthcare system as it promotes horizontal gene transfer.
Chemical composition of Cymbopogon citratus essential oil and its effect on mycotoxigenic Aspergillus species
(African Journal of Food Science, 2011) Matasyoh, Josphat C.; Wagara, Isabel N.; Nakavuma, Jesca L.; Kiburai, Anderson M.
This study evaluated the antifungal activity of essential oil of Cymbopogon citratus (Poaceae) against five mycotoxigenic species of the genus Aspergillus (Aspergillus flavus, Aspergillus parasiticus, Aspergillus ochraceus, Aspergillus niger and Aspergillus fumigatus) isolated from maize samples. The oil of C. citratus was obtained by hydro-distillation and analysed by Gas Chromatography – Mass Spectrometry (GC-MS). The oil was dominated by monoterpene hydrocarbons which accounted for 94.25% of the total oil and characterised by a high percentage of geranial (39.53%), neral (33.31%), and myrecene (11.41%). The antifungal activity tests showed that the oil was active against all the five Aspergillus species. The extent of inhibition of fungal growth was dependent on the concentration of the oil. The activity of the oil against the mycotoxigenic fungi had Minimun Inhibitory Concentration (MIC) values ranging from 15 to 118 mg/ml. These results show that the essential oil of C. citratus has antifungal activities against fungi that are the producers of poisonous mycotoxins found in foods. This oil can be used in food preservation systems to inhibit the growth of moulds and retard subsequent mycotoxin production.
Chemical tick control practices in southwestern and northwestern Uganda
(Ticks and tick-borne diseases, 2018) Vudriko, Patrick; Okwee-Acai, James; Byaruhanga, Joseph; Tayebwaa, Dickson S.; Okech, Samuel G.; Tweyongyere, Robert; Wampande, Eddie M.; Ademun Okurut, Anna R.; Mugabi, Kenneth; Muhindo, Jeanne B.; Nakavuma, Jesca L.; Umemiya-Shirafuji, Rika; Xuan, Xuenan
Tick acaricide failure is one of the leading challenges to cattle production in Uganda. To gain an understanding into the possible drivers of acaricide failure, this study characterized the current chemical tick control practices in the southwestern (Mbarara, Mitooma and Rukungiri districts) and northwestern (Adjumani district) regions of Uganda. A total of 85 farms participated in a survey that utilized a semi-structured questionnaire. Moreover, ticks were collected to determine the most common species on the farms. Tick acaricide failure was mainly encountered in the districts where 95% (60/63) of the farms reared exotic cattle (dairy cross-breeds) under a paddocking (fenced) system. In the northwestern region, local cattle were reared in communal grazing areas. All farms used chemical acaricides for tick control, predominantly amidine (amitraz) (48%, 41/85) and co-formulated organophosphates and pyrethroids (38%, 32/85). The spraying method was the most common (91%, 77/85) acaricide application technique, with cattle crush (81%, 69/85) as a common means of physical restraint. Less than optimal tick control practices encountered included use of substandard equipment for spraying, inappropriate dilutions, frequent interaction between animals in neighboring farms despite lack of synchronized chemical tick control and malpractices in acaricide rotation. Only Rhipicephalus appendiculatus and R. (Boophilus) decoloratus ticks were found in the southwestern region, where 51% (32/63) of the farmers used high acaricide concentrations above the manufacturers’ recommendation. Farmers in the northwestern region used 2.2 times less acaricide volume per cattle than those in the southwestern region, and more diverse tick species were encountered. Toxic effects of acaricide to cattle and workers were reported by 13% (11/85) and 32% (27/85) of the respondents, respectively. All 27 cases of human acaricide toxicity reported were from the southwestern region. Overall, our findings may inform strategies for more prudent chemical tick control and safe acaricide handling to benefit animal welfare, food safety and public health.
Comparative study of in-vitro antimicrobial activity and phytochemical composition of Sida cuneifolia fruits, leaves, and stem bark extracts
(International Journal of Basic & Clinical Pharmacology, 2014) Nalubega, Rebecca; Nyanzi, Steven A.; Nakavuma, Jesca L.
Background: Sida cuneifolia plant parts are important in ethno-veterinary medicine, but no studies exist on a comparative evaluation of phytochemical composition and antimicrobial properties of fruits, stem bark and leaves. This study evaluated and compared extraction yields, phytochemical composition as well as antibacterial and antifungal properties of ether, methanol and aqueous crude extracts of fruits, leaves, and stem bark of S. cuneifolia. Methods: Yields of extracts were determined, and qualitative phytochemical screening tests were carried out to establish their composition. Crude extracts were screened against five bacteria and two fungi. Agar disk diffusion technique was used to determine the inhibition zone diameters. Broth micro-dilution method was used to determine the minimum inhibition concentrations (MIC) and minimum bactericidal concentrations (MBC). Results: Triterpene aglycones, sterols, tannins, athracene derivatives, polyuronides and glucides were found in intense mounts in S. cuneifolia fruits. Leaves contained intense amounts of carotenoids, tannins, polyuronides and coumarin derivatives. For the leaves, methanol extracts had MICs and MBCs as low as (≤3.13 mg/ml) against the majority (6/7) microorganisms hence had the best activity. Considering the stem bark, the ether extracts had the best antimicrobial activity with MICs as low as ≤3.13 mg/ml against 6/7 microorganisms. For the fruits, the ether extracts had the best antibacterial activity with MICs and MBCs as low as (≤3.13 mg/ml) against all tested bacteria. Conclusion: The study provides scientific evidence for ethno-veterinary use of S. cuneifolia leaves, fruits and stem bark, and this can be exploited in the transformative development of ethno-medicine.
Establishment of a transformation protocol for Uganda’s yellow passion fruit using the GUS gene
(African Journal of Biotechnology, 2019) Tuhaise, Samuel; Nakavuma, Jesca L.; Adriko, John; Ssekatawa, Kenneth; Kiggundu, Andrew
Horticulture is one of the fastest growing sectors in Uganda, exporting products worth US$100 million annually. Passion fruit (Passiflora edulis) growing and export is one of the critical contributors to this sector employing over a million farmers. However, a number of biotic and abiotic constraints have initiated widespread enterprise abandonment by farmers. Passiflora improvement efforts by conventional breeding has had limited success calling for research into alternative approaches such as genetic engineering. The study aimed at optimizing existing protocols to develop an efficient and reproducible Agrobacterium mediated transformation system to suit Uganda’s Passiflora cultivars. Agrobacterium tumefaciens strain AGL1 (OD600 of 0.5) harbouring pCAMBIA2301 containing the GUS (uidA) reporter gene was used to infect pre-cultured leaf discs. Leaf discs were then vacuum infiltrated for 1.5 min at 750 mmHg followed by a three day co-cultivation period on MS + acetosyringone (100 μml-1). Putatively transgenic yellow passion fruit shoots were induced on Murashige and Skoog (MS) selection media supplemented with benzylaminopurine (BAP) 8.9 μM, kanamycin (100 mgL-1mgl) and cefotaxime (500 mgL-1). Developed shoots were then transferred to elongation media (MS + 0.44 μM BAP) and later rooted on 5.37 μM naphthaleneacetic acid (NAA). Genetic transformation was monitored using GUS staining. A single independently transformed plant was confirmed by polymerase chain reaction (PCR), translating in a transformation efficiency of 0.456%. A viable in vitro transformation protocol for Uganda’s yellow passion fruit directly from leaf discs was developed using GUS reporter gene. Further investigations are required to improve the reported protocols transformation efficiency.
Ethnobotanical uses of Lantana trifolia L. and Sida cuneifolia Roxb. in Mukungwe and Wabinyonyi sub-counties of central Uganda
(Journal of Complementary Medicine Research, 1970) Nalubega, Rebecca; Nyanzi, Steven A.; Nakavuma, Jesca L.; Kamatenesi-Mugisha, Maud
Aim: This was an ethnobotanical study that was carried out to establish the traditional uses of Lantana trifolia L. and Sida cuneifolia Roxb. plants in selected parts of Central Uganda. Methods: The ethnobotanical study was done in August and September, 2012 in Mukungwe and Wabinyonyi sub-counties in Masaka and Nakasongola Districts respectively located in Central Uganda. Study sites and respondents were purposefully selected and information was obtained through semi-structured interview guides, key informant interview guides as well as observations. Eighty respondents were considered for semi-structured interviews and 15 for key informant interviews. Results: Seven ethnobotanical uses for Lantana trifolia were cited by respondents and majority (46.25%) of them used it as a herbal remedy. As a herbal remedy, Lantana trifolia managed 13 human disease conditions and mainly used in the management of cough and common colds by 22.5% of the respondents. Four ethnobotanical uses were cited for Sida cuneifolia and majority of the respondents (62.5%) used it as a herbal remedy as well as sweeping brooms. As a herbal remedy, Sida cuneifolia was reported to be useful in management of 12 disease conditions, fractures and sprains (bone setting) being mentioned by the majority of the of respondents (36.25 %). Conclusion: In conclusion, Lantana trifolia and Sida cuneifolia were culturally important ethnomedicines. Scientific validation of traditional claims as well as conservation of these plants should be encouraged in order to preserve and promote their use.
Genome Sequences of Bacteriophages UPEC01, UPEC03, UPEC06, and UPEC07 Infecting Avian Pathogenic Escherichia coli
(Microbiology Resource Announcements, 2022) Kazibwe, George; Ndekezi, Christian; Alinaitwe, Ruth; Alafi, Stephen; Nanteza, Ann; Magambo, Phillip K.; Nakavuma, Jesca L.
Here, we present the genome sequences of four bacteriophages that infect avian pathogenic Escherichia coli. The phages were isolated from raw sewage in Kampala, Uganda. The genome sizes of the phages ranged between 143,140 bp and 178,307 bp, with an average G1C content of 41.25%. Phages infecting avian pathogenic Escherichia coli (APEC) have the potential to be applied as phage therapy in the management of avian colibacillosis, a devastating disease that is responsible for significant economic losses in the poultry industry (1). The emergence of multidrug-resistant pathogenic E. coli strains has sparked interest in the search for alternative control measures for bacterial pathogens, including, among others, the use of phages (2). In this study, whole-genome sequencing of bacteriophages was carried out to determine the genetic characteristics and the taxonomic identification or classification of these phages as part of a larger study aimed at identifying and establishing phage stocks that can be used to supplement the use of antibiotics in managing avian colibacillosis in Uganda. The bacteriophages in this study were isolated from sewage at the National Water and Sewerage Corporation treatment plant (Kampala, Uganda). Several E. coli field isolates (Table 1) obtained from chicken droppings were used as isolation hosts for the phages following previously described methods (3). Briefly, 10 mL of raw sewage was centrifuged (10,000 g for 10 min) to obtain a supernatant, which was added to 10 mL of 2 tryptic soy broth (TSB) containing 100 mL of overnight E. coli broth culture. The mixture was incubated (30°C for 48 h at 120 rpm) and centrifuged (7,000 rpm for 5 min at 4°C), and the supernatant was filtered (0.45mm). The phage lysate obtained was plaque purified three times to produce a uniform phage stock. The isolated phages that could infect the APEC isolates from chickens that had died from colibacillosis were selected (4). Genomic DNA was extracted from the phages using 2% SDS and purified using a Qiagen Genomic-tip 100/G kit according to the manufacturer’s instructions.
Green Strategy–Based Synthesis of Silver Nanoparticles for Antibacterial Applications
(Frontiers in Nanotechnology, 2021) Ssekatawa, Kenneth; Byarugaba, Denis K.; Kato, Charles D.; Wampande, Eddie M.; Ejobi, Francis; Nakavuma, Jesca L.; Maaza, Malik; Sackey, Juliet; Nxumalo, Edward; Kirabira, John B.
Antibiotics have been the nucleus of chemotherapy since their discovery and introduction into the healthcare system in the 1940s. They are routinely used to treat bacterial infections and to prevent infections in patients with compromised immune systems and enhancing growth in livestock. However, resistance to last-resort antibiotics used in the treatment of multidrug-resistant infections has been reported worldwide. Therefore, this study aimed to evaluate green synthesized nanomaterials such as silver nanoparticles (AgNPs) as alternatives to antibiotics. UV-vis spectroscopy surface plasmon resonance peaks for AgNPs were obtained between 417 and 475 nm. An X-ray diffraction analysis generated four peaks for both Prunus africana extract (PAE) and Camellia sinensis extract (CSE) biosynthesized AgNPs positioned at 2θ angles of 38.2°, 44.4°, 64.5°, and 77.4° corresponding to crystal planes (111), (200), (220), and (311), respectively. A dynamic light-scattering analysis registered the mean zeta potential of +6.3mV and +0.9 mV for PAE and CSE biosynthesized nanoparticles, respectively. Fourier transform infrared spectroscopy spectra exhibited bands corresponding to different organic functional groups confirming the capping of AgNPs by PAE and CSE phytochemicals. Field emission scanning electron microscopy imaging showed that AgNPs were spherical with average size distribution ranging from 10 to 19 nm. Biosynthesized AgNPs exhibited maximum growth inhibitory zones of 21mm with minimum inhibitory concentration and minimum bactericidal concentration of 125 and 250 μg/ml, respectively, against carbapenem-resistant bacteria
Herbal medicine used for the treatment of diarrhea and cough in Kampala city, Uganda
(Tropical Medicine and Health, 2022) Walusansa, Abdul; Asiimwe, Savina; Ssenku, Jamilu E.; Anywar, Godwin; Namara, Milbert; Nakavuma, Jesca L.; Kakudidi, Esezah K.
Globally, diarrheal and respiratory diseases are among the main causes of mortality and morbidity. In Uganda, cities are facing proliferation of trade in herbal medicines (HM), including those for diarrhea and/or cough. Information on the economic, and the ethnopharmacological aspects of these HM is scarce, deterring the sector from achieving optimal capacity to support national development. We profiled the anti-diarrhea and/or anti-cough HM, and the basic economic aspects of HM trade in Kampala city, to support ethnopharmacological knowledge conservation and strategic planning. Methods: A cross-sectional survey was conducted on 65 herbalists using semi-structured questionnaires. This was supplemented by an observational survey using a high-resolution digital camera. Data were collected following the guidelines for research on HM, established by Uganda National Drug Authority, and World Health organization. Results: Eighty-four plant species from 41 families were documented. Fabaceae and Myricaceae had the highest number of species (9, 10.7% each). Citrus limon (L.) Osbeck was the most commonly cited for cough, with a relative frequency of citation (RFC) of 1.00, and its relative medical importance was not significantly different from the other top 5 species except for Azadirachta indica A.Juss (RFC = 0.87). Entada abyssinica A. Rich (RFC = 0.97) was the most cited for diarrhea. Trees (34, 40.5%) were mostly used, and mainly harvested from wild habitats (55.2%) in 20 districts across Uganda. These HM were mainly sold as powders and concoctions, in markets, shops, pharmacies, and roadside or mobile stalls. The highest prices were Uganda Shillings (UGX) 48,000 ($13.15)/kg for Allium sativum L, and UGX 16,000 ($4.38)/kg for C. limon. All participants used HM trade as a sole source of basic needs; majority (60.0%) earned net monthly profit of UGX. 730,000 ($200) ≤ 1,460,000 ($400). The main hindrances to HM trade were the; disruptions caused by the COVID-19 pandemic (n = 65, 100%), and the scarcity of medicinal plants (58, 89.2%). Conclusion: There is a rich diversity of medicinal plant species traded in Kampala to treat diarrhea and cough. The HM trade significantly contributes to the livelihoods of the traders in Kampala, as well as the different actors along the HM value chain throughout the country
Influence of physicochemical parameters on storage stability: Microbiological quality of fresh unpasteurized fruit juices
(Food Science & Nutrition, 2017) Kaddumukasa, Phoebe P.; Imathiu, Samuel M.; Mathara, Julius M.; Nakavuma, Jesca L.
Fresh juices rich in health and nutritional benefits are valued for their fresh flavor, taste, and aroma. These juices’ quality however is affected by factors like temperature, light, and microbiological contamination significantly changing physicochemical parameters and storage stability. Physicochemical and microbiological analyses of passion fruit, pineapple, and mango juices in dark and light bottles at 24°C and 4°C were conducted in Kampala, Uganda for 12 days. Physicochemical parameters significantly reduced (p < .05) storage stability of fresh juices, while no significant changes (p > .05) were observed for the microbiological analyses. pH values ranged from 3.0 to 4.2 (dark) bottles and 2.9 to 4.0 (light) bottles for juices at 24°C and 4°C. °Brix values were from 1.0 to 5.5 for dark and clear bottles at 24°C and 4°C. TTA (%) values ranged from 1.1 to 7.2 (dark) bottles and 1.1 to 7.4 for (light) bottles at 24°C and 4°C. Ascorbic acid content ranged from 3.5 to 61.0 mg/ 100 ml and 5.5 to 56.7 mg/100 ml for juices in dark and clear bottles, respectively. total plate counts ranged from 1.3 × 10⁶ to 3.3 × 107 CFU/ml (dark bottles at 24°C) to 3.5 × 10³ to 3.3 × 108 CFU/ml (dark bottles at 4°C). For juices in light bottles, total plate counts ranged from 1.8 × 10⁶ to 8.0 × 107 CFU/ml (24°C) and 2.7 × 10⁴ to 1.5 × 108 CFU/ml (4°C). High microbial loads suggest the use of poor processing techniques and lack of good hygiene which lower quality and reduce storage stability of juices. Storage temperature greatly reduces physicochemical parameters both at ambient and refrigeration temperatures. This implies that temperature control for unpasteurized juices is critical in order to inhibit microorganism metabolic activities which accelerate biodeterioration leading to spoilage and short shelf life. Fresh unpasteurized juices stored at 24°C and 4°C may safely be consumed within 1 and 2 days, respectively.
Isolation and Characterization of Novel Lytic Phages to Combat Multidrug-Resistant E. coli and Salmonella spp.
(Journal of Microbiology and Infectious Diseases, 2021) Nyachieo, Atunga; Alafi, Stephen; Jepkurui Mutai, Ivy; Ngolobe, Benson; Nabunje, Ritah; Nakavuma, Jesca L.
Objectives: Escherichia coli and some Salmonella enterica serovars are zoonotic pathogens affecting livestock and humans. These pathogens cause significant loss of productivity in livestock, severe morbidity and mortality in humans, and have high antibiotic resistance profiles. Therefore, the exploitation of lytic phages for therapeutic purposes is important for eliminating these resistant bacterial strains. Methods: Thirty-four bacterial stock isolates comprised of 23 E. coli and 11 Salmonella spp. strains were evaluated for antimicrobial susceptibility to seven antibiotics using the Kirby-Bauer disk diffusion test. The antibiotics included Ciprofloxacin, Trimethoprim-Sulphamethoxazole, Gentamycin, Imipenem, Ceftriaxone, Cefotaxime, and Ofloxacin. Twelve (12/23) E. coli and (2/11) Salmonella spp. exhibited antimicrobial resistance. Selected six (6/12) drug-resistant E. coli strains were subjected to three different phages (PA5, EHEC005, C11S1A) for efficacy and host range assay. Similarly, two (2/2) resistant Salmonella strains were exposed to one Salmonella phage A23 for efficacy and host range assay. The E. coli (C11S1A) phage, which infected most bacterial hosts, was evaluated for optimal efficiency at various pH and temperatures. Results: E. coli isolates had the highest resistance 12/23 (52%) compared to Salmonella spp. 2/11(18%) (p<0.05). Most resistance was against Trimethoprim-Sulphamethoxazole (44%) and (9%) for E. coli and Salmonella spp., respectively. Furthermore, E. coli (C11S1A) phages killed all the Escherichia coli strains, while Salmonella phage A23 only lysed the host bacteria. The E. coli (C11S1A) phages were highly efficacious at 37 0C and pH 7.4.
Medically important bacteria isolated from commercial herbal medicines in Kampala city indicate the need to enhance safety frameworks
(Scientific Reports, 2022) Walusansa, Abdul; Nakavuma, Jesca L.; Asiimwe, Savina; Ssenku, Jamilu E.; Aruhomukama, Dickson; Sekulima, Tahalu; Kafeero, Hussein M.; Anywar, Godwin; Katuura, Esther; Nabatanzi, Alice; Musisi, Nathan L.; Tugume, Arthur K.
The high global bacterial infection burden has created need to investigate the neglected potential drivers of pathogenic bacteria, to inform disease prevention. Kampala is facing a proliferation of herbalists, selling herbal medicine (HM), of largely unregulated microbiological quality. We evaluated the bacterial contamination burden in HM sold in Kampala, to support evidence-based redress. The total viable loads (TVL), total coliform counts (TCC), E. coli counts, and prevalence of selected bacterial strains in 140 HM were examined using conventional culture, following the guidelines of World Health Organization (WHO), and Uganda National Drug Authority (NDA). Data were analyzed using D’Agostino-Pearson test, frequencies, proportions, Chi-square, and Mann–Whitney U test with STATA version-15.0. Fifty (35.7%), fifty-nine (42.1%), and twelve (8.6%) HM were unsafe for human use because they exceeded WHO’s permissible limits for TVL, TCC, and E. coli counts respectively. Solids had significantly higher mean TVL than liquids. Violation of NDA’s guidelines was significantly associated with high TVL. Fifty-nine bacteria, viz., Klebsiella pneumoniae (n = 34; 57.6%), Escherichia. coli (12; 20.3%), Staphylococcus aureus (7; 11.9%), Klebsiella oxytoca (3; 5.1%), Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. (1; 1.7% each), were isolated from 45 (32.1%) samples. These bacteria can cause severe clinical diseases, and promote deterioration of HM potency.
Phage banks as potential tools to rapidly and cost effectively manage antimicrobial resistance in the developing world
(Current Opinion in Virology, 2022) Nagel, Tobi; Musila, Lillian; Muthoni, Milkah; Nikolich, Mikeljon; Nakavuma, Jesca L.; Clokie, Martha R. J.
Lower and middle-income countries seldom develop vaccines and therapeutics for their own populations and are dependent on supplies from industrialized countries, which are often hampered by financial or supply chain limitations. This has resulted in major delays in delivery with significant loss of life, as seen with the coronavirus pandemic. Since the vast majority of deaths from the antimicrobial resistance crisis are expected to occur in developing countries, there is an urgent need for in-country production of antibacterial therapies such as phages. Nationally controlled phage banks might provide such a solution since locally developed phage therapies tailored to endemic bacterial strains could offer cost-effective antibiotic alternatives
Prevalence and dynamics of clinically significant bacterial contaminants in herbal medicines sold in East Africa from 2000 to 2020: a systematic review and metaanalysis
(Tropical Medicine and Health, 2021) Walusansa, Abdul; Asiimwe, Savina; Kafeero, Hussein M.; Iramiot, Stanley J.; Ssenku, Jamilu E.; Nakavuma, Jesca L.; Kakudidi, Esezah K.
Infectious diseases remain a leading cause of mortality and morbidity around the world, and those caused by bacteria are common in the East African region. In this region, trade and consumption of herbal medicine has been expanding in the recent decades. Herbal medicines may be contaminated with pathogenic bacteria; however, there is limited information due to fragmented studies in East Africa. In this meta-analysis, we critically analyzed original research related to the incidence of pathogenic bacterial contaminants of HM in the East African region since 2000. The aim was to create a comprehensive understanding of the extent and dynamics of bacterial contamination in HM, to guide future research and concerted public health protection in the region. Methodology: The study was conducted according to the standards of the Preferred Reporting Items for Systematic Reviews and Meta-analyses. We searched and evaluated published articles from eleven electronic databases (Google Scholar, PubMed, HerbMed, MEDLINE, Science Direct, Scifinder Scholar, Cochrane Library, International Pharmaceutical Abstracts, EMBASE, Biological Abstracts and Commonwealth Agricultural Bureau Abstracts). Prevalences of different bacterial species, Cochran’s Q test, and the I2 statistic for heterogeneity were evaluated using a software called MedCalcs. Random and fixed effects models were used to determine the pooled prevalence of clinically significant bacteria from studies which were included in this meta-analysis. The potential sources of heterogeneity were examined through sensitivity analysis, sub-group analysis, and meta-regression at 95% level of significance.
Prevalence of pathogenic Klebsiella pneumoniae based on PCR capsular typing harbouring carbapenemases encoding genes in Uganda tertiary hospitals
(Antimicrobial Resistance & Infection Control, 2021) Ssekatawa, Kenneth; Byarugaba, Denis K.; Nakavuma, Jesca L.; Kato, Charles D.; Ejobi, Francis; Tweyongyere, Robert; Wampande, Eddie M.
Background: Klebsiella pneumoniae is an opportunistic pathogen that has been implicated as one of commonest cause of hospital and community acquired infections. The K. pneumoniae infections have considerably contributed to morbidity and mortality in patients with protracted ailments. The capacity of K. pneumoniae to cause diseases depends on the presence of an array virulence factors. Coexistence and expression of virulence factors and genetic determinants of antibiotic resistance complicates treatment outcomes. Thus, emergence of pathogenic MDR K. pneumoniae poses a great threat to the healthcare system. However, the carriage of antibiotic resistance among pathogenic K. pneumoniae is yet to be investigated in Uganda. We sought to investigate the carbapenem resistance profiles and pathogenic potential based on capsular serotypes of K. pneumoniae clinical isolates. Methods: This was a cross sectional study involving use of archived Klebsiella pneumoniae isolates collected between January and December, 2019 at four tertiary hospitals in Uganda. All isolates were subject to antimicrobial susceptibility assays to determine phenotypic antibiotic resistance, pentaplex PCR to detect carbapenemases encoding genes and heptaplex PCR to identify capsular serotypes K1, K2, K3, K5, K20, K54 and K57. Results: The study found an overall phenotypic carbapenem resistance of 23.3% (53/227) and significantly higher genotypic resistance prevalence of 43.1% (98/227). Over all, the most prevalent gene was blaOXA-48-like (36.4%), followed by blaIMP-type (19.4%), blaVIM-type (17.1%), blaKPC-type (14.0%) and blaNDM-type (13.2%). blaVIM-type and blaOXA-48-like conferred phenotypic resistance in all isolates and 38.3% of isolates that harbored them respectively. Capsular multiplex PCR revealed that 46.7% (106/227) isolates were pathogenic and the predominantly prevalent pathotype was K5 (18.5%) followed by K20 (15.1%), K3 (7.1%), K2 (3.1%) and K1 (2.2%). Of the 106 capsular serotypes, 37 expressed phenotypic resistance; thus, 37 of the 53 carbapenem resistant K. pneumoniae were pathogenic. Conclusion: The high prevalence of virulent and antibiotic resistant K. pneumoniae among clinical isolates obtained from the four tertiary hospital as revealed by this study pose a great threat to healthcare. Our findings underline the epidemiological and public health risks and implications of this pathogen.
A review of phage mediated antibacterial applications
(Alexandria Journal of Medicine, 2021) Ssekatawa, Kenneth; Byarugaba, Denis K.; Kato, Charles D.; Wampande, Eddie M.; Ejobi, Francis; Tweyongyere, Robert; Nakavuma, Jesca L.
For over a decade, resistance to newly synthesized antibiotics has been observed worldwide. The challenge of antibiotic resistance has led to several pharmaceutical companies to abandon the synthesis of new drugs in fear of bacteria developing resistance in a short period hence limiting initial investment return. To this effect, alternative approaches such as the use of bacteriophages to treat bacterial infections are being explored. This review explores the recent advances in phage-mediated antibacterial applications and their limitations. Methods: We conducted a comprehensive literature search of PubMed, Lib Hub and Google Scholar databases from January 2019 to November 2019. The search key words used were the application of bacteriophages to inhibit bacterial growth and human phage therapy to extract full-text research articles and proceedings from International Conferences published only in English. Results: The search generated 709 articles of which 95 full-text research articles fulfilled the inclusion guidelines. Transmission Electron Microscopy morphological characterization conducted in 23 studies registered Myoviruses, Siphoviruses, Podoviruses, and Cytoviruses phage families while molecular characterization revealed that some phages were not safe to use as they harbored undesirable genes. All in vivo phage therapy studies in humans and model animals against multidrug-resistant (MDR) bacterial infection provided 100% protection. Ex vivo and in vitro phage therapy experiments exhibited overwhelming results as they registered high efficacies of up to 100% against MDR clinical isolates. Phage-mediated bio-preservation of foods and beverages and bio-sanitization of surfaces were highly successful with bacterial growth suppression of up to 100%. Phage endolysins revealed efficacies statistically comparable to those of phages and restored normal ethanol production by completely eradicating lactic acid bacteria in ethanol fermenters. Furthermore, the average multiplicity of infection was highest in ex vivo phage therapy (557,291.8) followed by in vivo (155,612.4) and in vitro (434.5).
Toxicity Studies on Anti-fungal Essential Oils Extracted from Selected Aromatic Plants from Mabira and Kakamega Forests, East Africa
(European Journal of Medicinal Plants, 2016) Nakavuma, Jesca L.; Matasyoh, Josphat C.; Wagara, Isabel N.; Kalema, John; Alinaitwe, Lordrick
In a bid to explore for grain bio-preservatives, essential oils extracted from Cymbopogon citratus, Rosmarinus officinalis, Monanthataxis littoralis and Aframomum angustifolium, that were earlier established to have anti-mold activity, were evaluated for their biosafety by determining the oral LD50. Methods: The essential oils were extracted by hydro-distillation from aromatic plants collected from Kakamega and Mabira forests in Kenya and Uganda, respectively. Acute oral toxicity was established using mice by determining the LD50; after which sub-acute toxicity studies were performed. The animals were observed for behavioural changes; and the gross and histopathological effects, if any, on the intestinal mucosa, spleen, lungs, liver, kidney and heart were noted. Results: The oral LD50 for Cymbopogon citratus, Rosmarinus officinalis, Monanthataxis littoralis and Aframomum angustifolium essential oils were established as 7,046.90; 4,723.33; 13,335.82; and 17,539.82 (mg/kg body weight), respectively. In all cases, increased breathing rates were observed, however Rosemary also caused lethargy and convulsions. Grossly, no changes were seen in the liver, kidney, lungs, heart and spleen from both the control and the treated mice except for Monanthataxis littoralis where the lungs and liver seemed changed; and the urinary bladder distended. However, the latter effects were noted at higher doses than the established oral LD50. Histopathologically, thickened intestinal mucosa lining; tubular degeneration and proteinuria in the kidneys; vascular congestion, focal necrosis and hydropic degeneration of hepatocytes in the liver, were encountered. Conclusion: Basing on the oral LD50 in mice, all oils were safe and can be explored further as antimold grain preservatives. However, Rosmarinus officinalis was marginally safe as per the OECD guidelines. The histopathological effects of Monanthataxis littoralis essential oil need to be investigated further.

Browsing by Author "Nakavuma, Jesca L."

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