Browsing by Author "Mzula, Alexanda"

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Antibiotic-resistant microbial populations in urban receiving waters and wastewaters from Tanzania
(Environmental Chemistry and Ecotoxicology, 2023) Ripanda, Asha Shabani; Rwiza, Mwemezi J; Nyanza, Elias Charles; Miraji, Hossein; Bih, Numfor Linda; Mzula, Alexanda; Mwega, Elisa; Njau, Karoli N; Vuai, Said Ali Hamad; Machunda, Revocatus L
Antimicrobial resistance against certain medications in the pathogenic microbial community is globally increasing due to the continual discharge and disposal of pharmaceuticals in the environment. The phenomenon resulted in significant antibiotic resistance among several exposed Enterobacteriaceae species, with wastewater treatment plants (WWTPs) and rivers serving as significant reservoirs. Despite antibiotic resistance being a tragedy, particularly in treating diseases by using antibiotics, local and regional studies indicating the severity, resistant species and the molecular level insight into these pathogens are scarce, thus requiring immediate intervention. This study, therefore, investigated wastewater from wastewater treatment ponds and receiving waters for the presence of resistant patho- gens through phenotypical and molecular approach screening of their genes. Among the 57 analyzed samples, 18 (67%, n = 27) isolates of Klebsiella spp.., 4 (80%, n = 5) isolates of Proteus spp., 1 (100%, n = 1) of isolated Pseudomonas aeruginosa and 6 (18%, n = 34) of E. coli found were resistant to at least 1 among the tested antibiotics. E. coli had an 83% higher proportion of multi-drug resistance (MDR) than Klebsiella spp.., which had 68.5%, and no MDR was shown by P. aeruginosa isolates. Among the 20 bacterial isolates of antibiotic-resistant genes, showed that E. coli harboured 39%, followed by 22% of Klebsiella spp. Eleven (11) isolates of these 20 (55%) contained sulphonamides resistant genes: Sul 1 (n = 4) and Sul 2 (n = 7). Ten (10) isolates (50%) contained the tetracycline- resistant genes in which 4 isolates showed the Tet A, Tet B – 1 and 5 isolates contained Tet D. β-lactamases (bla CTX-M and bla SHV) were found in 7 isolates (35%). The existence of these antibiotic-resistant species in the urban receiving and wastewater presents a threat of transmission of diseases to humans and animals that are not cured by the existing medications, jeopardizing public health safety.
Assessing the awareness, knowledge, attitude and practice of the community towards solid waste disposal and identifying the threats and extent of bacteria in the solid waste disposal sites in Morogoro municipality in Tanzania
(IISTE, 2015) Chengula, Augustino; Lucas, Bahati K; Mzula, Alexanda
Solid wastes comprise all the wastes arising from human and animal activities that are normally solid, discarded as useless or unwanted materials. Health hazards associated with improper disposal of solid wastes to the community were investigated in Morogoro municipality. The aim of the project was to investigate the solid waste disposal practices and their health hazard implications to the community in Morogoro municipality. The study was conducted by considering several solid waste disposal sites based on three methods; observation, questionnaire survey and microbiological analysis. Based on observation method, several solid waste practices were detected including collection of wastes using trucks, wheel barrow, carriers made from elephant grasses and cement bags. Questionnaire survey pinpointed several diseases caused by solid wastes such as malaria, diarrhea, dysentery, cholera, typhoid and worm diseases from the respondents. From microbiological analysis, several pathogenic bacteria were identified from the solid disposal sites. The bacteria with their frequency of isolation identified were: Salmonella typhimurium (16.7%), Shigella dysenteriae (16.7%), Citrobacter freundii (8.3%), Citrobacter amalonaticus (8.3%), Aerobacter aerogenes (8.3%), Proteus vulgaris (16.7%), Klebsiella oxyotoca (8.3%), Klebsiella (8.3%), E.coli (8.3%). Solid waste generated by the daily activities of the people needs to be properly managed in such a way that it minimizes the risk to the environment and human health. Inadequate collection and disposal of solid waste is a major factor in the spread of disease and environmental degradation.
Characterization of Aeromonads and development of Vaccine candidate from Aeromonas Hydrophila Isolated from Tilapia fish farms in Tanzania
(Sokoine University of Agriculture, 2020) Mzula, Alexanda
Tanzania produces less than half of the country annual demand in fish. Therefore, there is an urgent need to produce more fish, particularly through fish farming. However, aeromonads infections cause major lose in aquaculture worldwide and especially in developing countries, including Tanzania, lacking advanced capacity for fish disease control and prevention. Poor fish farming management practices, lack of data on prevalence, emergence of resistances to commonly used drugs, drug residues and limited capacity to control aeromonads bacterial infections emerged as major health problems in fish farming in Tanzania. This study aimed to characterise the aeromonads species circulating in fish farms and then develop a monovalent vaccine candidate from selected prevalent aeromonads specie for supporting tilapia fish farming improvement in Tanzania. A cross sectional study was conducted in Ruvuma, Mbeya, Iringa and Kilimanjaro regions between February 2017 and October 2018. A questionnaire was administered to 32 selected fish farmers to explore their knowledge on pond, fish health and diseases management practices. The results showed that the selected farmers had limited knowledge on pond, fish health and disease management practices. On- farm training on the same to these farmers would improve their knowledge. A total of 816 whole fish samples were aseptically collected from these 32 fish farms to detect and identify aeromonads using molecular methods in order to establish the prevalence and characterise their virulence properties. The overall prevalence of 24.6% was recorded. Seventy five percent of the isolates had virulence genes of varying combinations and the in-vivo study showed high mortality (98.3%) to isolates with more virulence genes indicating their capacity to establish disease in a favourable environment. The Aeromonas hydrophila strain TZR7- 2018 was selected and attenuated using a novel thermo-continuous sub-culturing method to develop a vaccine candidate. The experimental study was carried out to assess its protective efficacy. The results showed that the vaccine candidate had acceptable protective efficacy of 82.3% and 71.4% when given through intraperitoneal injection (IP) and immersion (IM); respectively. To the best of my knowledge this study reports the development of thermo attenuated and stabilized A. hydrophila vaccine candidate for the first time in Tanzania or elsewhere
Current state of modern biotechnological-based aeromonas hydrophila Vaccines for aquaculture: a systematic review
(Hindawi BioMed Research International, 2019-07-29) Mzula, Alexanda; Wambura, Philemon N; Mdegela, Robinson H; Shirima, Gabriel M
This systematic review describes what “the cutting edge vaccines for Aeromonas hydrophila are”. The focus is on types of high tech biotechnological based vaccines, target gene or antigen in developing these vaccines, and challenge model fish species used in vaccines efficacy testing. Vaccines delivery methods, immune response, and their efficacy, adjuvant or carrier systems used, and the overall experimental setup or design of the vaccines under investigation are also described. The search for the original papers published between 2009 and 2018 was conducted in June of 2018, using the PubMed and Google scholar electronic database. Twenty- three (23/4386) studies were included in the final assembly using PRISMA guidelines (Protocol not registered). Recombinant protein vaccines were the highly experimented type of the modern biotechnological based vaccines identified in the selected studies (16/23; 70%). Outer membrane proteins (OMPs) of different β-barrels were shown to be a potential antigenic entity for A. hydrophila vaccines (57%). Intraperitoneal route with conventional carries or adjuvants was the highly applied delivery system while very few studies used herbal based vaccine adjuvants and nanomaterial as a vaccine carrier. Variation was observed in terms of protection levels in the selected studies. The experimental designs partly contributed to the observed variation. Therefore, recombinant vaccines that use new carrier system technologies and delivered through oral route in feeds would have been of great value for use in the prevention and control of A. hydrophila infections in fish. Despite the usefulness as academic tools to identify what is important in pathogenicity of the etiological agent to the host fish, these vaccines are only economically viable in very high-value animals. Therefore, if vaccination is a good option for A. hydrophila group, then simple autogenous vaccines based on accurate typing and evidence-based definition of the epidemiological unit for their use would be the most viable approach in terms of both efficacy and economic feasibility especially in low and middle-income countries (LMIC).
Determination of bacterial load and antibiotic Susceptibility testing of bacteria isolated from students’ toilets At Sokoine University of Agriculture, Morogoro, Tanzania
(Journal of Health, Medicine and Nursing, 2014) Chengula, Augustino; Lushino, Asha; Mzula, Alexanda; Mafie, Eliakunda; Mwega, Elisa; Makundi, Isaac; Peter, Emma
The circulation of infectious diseases in the community settings in urban and rural areas remains to be a hectic problem. One of the sources of microbial diseases is toilets. This study aimed at isolating, identifying and establishing bacterial loads associated with public restrooms in students’ hostels at Sokoine University of Agriculture in Morogoro, Tanzania. Samples were collected from a total of thirty toilets (60 samples) in different surfaces; (i) surfaces associated with toilets (toilet seats and toilet bowls), (ii) surfaces routinely touched with hands (door handles in and out of the restrooms, faucet handles and toilet flush handles) and (iii) the restroom floors. Samples were inoculated in MacConkey and Blood agar and then incubated at 37 o C for 24 hours. All isolates were sub cultured and identified based on macro- and micro-morphology and Standard Biochemical Tests. The establishment of total bacteria load was done using Standard Plate Count Method. The sensitivity testing of the isolates were carried out using the Disk Diffusion Method on nutrient agar plate. The following bacteria genera and species were isolated from the students’ toilets; Staphylococcus aureus (25.0%), Escherichia coli (36.7%), Pseudomonas aeruginosa (13.3%), Streptococcus pyogenes (6.7%), Proteus mirabilis (6.7%) and Klebsiella pneumonia (11.6%). The results from total bacterial count indicated that the surfaces routinely touched with hands had highest bacteria load compared to restroom floor and toilet seats. However, the differences of means among the surfaces were not statistically significant (P= 0.6762). Sensitivity testing of the isolates against commonly used antibiotics in the study area showed that all bacterial isolates tested were resistant and intermediate resistant to at least one antibiotic.
Phenotypic and molecular detection of Aeromonads infection in farmed Nile tilapia in Southern highland and Northern Tanzania
(Elsevier Ltd, 2019-07) Mzula, Alexanda; Wambura, Philemon N; Mdegela, Robinson H; Shirima, Gabriel M
Aeromonads disease outbreaks are now becoming a common phenomenon in freshwater farmed fish worldwide. In Tanzania, the aquaculture field is increasingly growing save to sustain food protein demand and strengthen household income. To avoid losses that tilapia fish farmers might account, information on magnitude of infection and characteristics of the aetiological agent is vital. This study aimed to establish the prevalence of aeromonads infection in farmed tilapia and assess pond and fish health management practices. A cross sectional study was carried out between February 2017 and October 2018 and a total of 816 whole fish samples were aseptically collected from 32 ponds in Ruvuma, Mbeya, Iringa and Kilimanjaro regions. During sampling, water quality parameters were taken and questionnaires to assess the knowledge of farmers were also provided. Isolation and identification of bacteria was conducted using conventional biotyping and molecular techniques. A total of 201 (80.4%) of 250 isolates that were conventionally identified were confirmed to be aeromonads by amplification of 820 bp rpoD gene, making the overall prevalence of 24.6% (201, n 1⁄4 816). Sequencing of rpoD gene and phylogenetic analysis revealed two aeromonads species, Aeromonas hydrophila and Aeromonas veronii. To the best of our knowledge this is the first report to establish the prevalence of aeromonads in apparently healthy farmed tilapia in Southern highlands and Northern zone of Tanzania. In addition it was observed that farmers were lacking proper knowledge and awareness on pond management practices and fish health management. In conclusion, the infection rate of aeromonads in apparently health tilapia coupled with lack of proper knowledge and awareness on pond and fish health management by fish farmers in the study area poses risk of diseases outbreaks in their farms in future. Therefore, it is recommended that the farmers should be trained on basic pond and fish health management and control strategies.
Virulence pattern of circulating aeromonads isolated from farmed nile tilapia in Tanzania and novel antibiotic free attenuation of aeromonas hydrophila strain tzr7-2018
(Aquaculture Reports, 2020) Mzula, Alexanda; Wambura, Philemon N; Mdegela, Robinson H; Shirima, Gabriel M
Aeromonads are gram-negative, rod-shaped, facultative anaerobes bacteria known to cause motile aeromonads septicemia diseases (MAS) in warm freshwater farmed fish. Outbreaks are associated with pathogenicity of aeromonads in fish which is partly contributed by virulence characteristics of the etiological agent. The objective of this study was to assess the virulence characteristics of the previously isolated and identified aeromonads, and attenuate potential Aeromonas hydrophila strain TZR7-2018 to serve as local vaccine candidate. Six virulence genes and other virulence characteristics were molecularly and phenotypically assessed both using in-vitro and in-vivo approaches. Attenuation of A. hydrophila parent strain TZR7-2018 + was performed by passaging through thermal continuous sub-culturing 40 times in Tryptic soy agar (TSA). Bacterin was prepared by formalin in- activation from the same parent strain. Humoral responses were assayed using quantitative serological agglu- tination test (qSAT) while protective efficacy was measured through relative percent survival (RPS). A total 240 Nile tilapia fingerlings with an average weight of 8.1 ± 0.4 g were used in all in-vivo studies. The presence of aerolysin (aer), cytotoxic enterotoxin (act), elastase (ahy), haemolysin (hly), serine (ser) and polar flagella (fla) genes were determined using PCR. Out of 201 isolates, 75.1 % (151/201) of the aeromonads possessed virulence genes (120=A. hydrophila and 31=Aeromonas veronii). The virulence gene pattern of aer/hly/fla was the most prominent with the prevalence of 12.6 %. The attenuated strain TZR7-2018 − showed reduced: colon size, multiplication rate, cell size and loss in; haemolysis, motility and capsule. Humoral responses increased gra- dually and reached maximum at day 28 in both attenuated and bacterin formulation given through in- traperitoneal (IP) injection and immersion (IM). A RPS of 82.3 %, 71.4 % and 85.1 %, were recorded to the attenuated vaccine given through IP and IM and bacterin provided through IP respectively. Therefore the attenuated strain TZR7-2018 − obtained through thermal continuous subculture technique and the bacterin proved to be efficacious and can serve as vaccine candidate.