Jackson Nyarongi Ombui - Academia.edu (original) (raw)

Papers by Jackson Nyarongi Ombui

Textile & Leather Review, 2021

Huge quantities of chromium-containing leather solid wastes are generated during the production o... more Huge quantities of chromium-containing leather solid wastes are generated during the production of chrome-tanned leather worldwide. Disposal of these huge quantities of leather solid wastes is a major challenge due to the presence of chromium, which is highly toxic (mainly in its hexavalent form) and detrimental to the environment. Sustainable and environmentally friendly methods of their disposal and treatment options for removing chromium are required so that the dechromed waste can be utilized to make useful products, such as fertilizer for soil conditioning, to improve agriculture, or other applications. In this study, therefore, a new method of dechroming leather solid wastes was designed, whose procedure and results were compared with three other commonly used methods. The focus of the various dechroming methods was on the evaluation of the degree of chromium extraction from chrome-tanned leather wastes without destroying the collagen tissues. The average total amount of extra...

Disposal of leather waste from urban tanneries is a major challenge. Sustainable and environmenta... more Disposal of leather waste from urban tanneries is a major challenge. Sustainable and environmentally friendly methods are required in urban settings. This paper therefore, deals with the identification and quantification of all types of tanned solid wastes generated by 6 pre-selected urban tanneries in Kenya vis a vis corresponding quantity of hides and skins processed. Questionnaire survey and key informant interviews were conducted. The data collected in this study was analysed using descriptive statistics, and the analysis showed that 1,443,000kg of chromium contaminated leather waste was generated by the 6 pre-selected tanneries in the month of study. The generated wastes constituted chrome shavings (32.1%), chrome splits and trimmings (36.2%), vegetable shavings (9.1%), vegetable splits and trimmings (14.9%), crust trimmings (3.5%), buffing dust (2.4%) and finished trimmings (1.8%), all of which amounted to 2,112,560kg for one month in the 6 pre-selected tanneries that were inv...

Background: Salmonellosis is considered one of the most widespread food-borne zoonoses in industr... more Background: Salmonellosis is considered one of the most widespread food-borne zoonoses in industrialized as well as developing countries. The presence of Salmonella in food animals at slaughter and the consequent cross-contamination of edible carcass tissues present a significant food safety hazard. Methodology: Samples were collected from randomly selected pigs at the Ndumbuini abattoir in Nairobi. Isolates were confirmed to be Salmonella by biochemical tests and characterised by serotyping, phage typing and plasmid analysis. Minimum inhibitory concentrations (MICs) of eight antimicrobials were determined and the resistant isolates were screened for resistance genes by PCR. Results: Sixteen (13.8%) of 116 samples were positive for Salmonella. Three Salmonella enterica subsp. enterica serovars, namely Saintpaul, Braenderup, and Heidelberg were identified, S. Saintpaul being predominant. Antimicrobial resistance was found in 35.7% of the isolates. The S. Heidelberg isolates were susceptible to all the antimicrobials tested. Multidrug resistance was found in 7.1% of the Salmonella isolates. Plasmids were only detected in S. Heidelberg. Ampicillin resistance was based on expression of a bla TEM gene, while chloramphenicol, streptomycin, and tetracycline resistances were encoded by the genes catA1, strA, and tet(A), respectively. Conclusions: Pigs may serve as reservoirs of antimicrobial resistant Salmonella and slaughterhouse cross-contamination of pork may be a food safety risk.

Textile & Leather Review

The unhairing stage of leather processing is associated with the production of significant amount... more The unhairing stage of leather processing is associated with the production of significant amounts of solid and liquid wastes. The use of enzymes to replace the polluting sulphides currently used for unhairing is a viable alternative. Various proteases from different Bacillus cereus strains as well as many other bacterial strains have been used successfully for the unhairing of skins. However, no previous work has assessed the use of the crude alkaline protease extract from Bacillus cereus strain 1-p, a novel Bacillus cereus strain obtained from the shores of Lake Bogoria - a soda lake in Kenya – in the unhairing of goatskins. This study, therefore, evaluates the potential of the protease extract from the Bacillus cereus strain 1-p to unhair goatskins. Optimum variables for unhairing using the protease were investigated. Complete unhairing was achieved within 12 hours at 27°C and pH 12 using the crude enzyme. The period and temperature required for complete unhairing were significan...

Tropical Animal Health and Production

Pan African Medical Journal

Introduction: unadulterated milk, free of antimicrobial residues is important for industrial proc... more Introduction: unadulterated milk, free of antimicrobial residues is important for industrial processing and consumers' health. Antimicrobial residues in foods of animal origin can cause adverse public health effects like drug resistance and hypersensitivity. Milk produced in Lamu West sub-county is sold raw directly to consumers. We estimated the compositional quality and prevalence of antimicrobial residues in informally marketed raw cow milk in Lamu West Sub-County, Kenya. Methods: we randomly recruited 152 vendors and 207 farmers from four randomly selected urban centers in a cross-sectional study and interviewed them using a pretested standardized questionnaire. A100-ml raw milk sample was aseptically collected from each vendor and farm and tested for antimicrobial residues using Charm Blue Yellow II kit following the European Union Maximum Residue Limits (EU-MRLs) while an Ekomilk® Analyzer was used to measure compositional quality where samples with either solid not fat (SNF) < 8.5 or added water ≥ 0.01% or both were considered adulterated. We analyzed data using univariate analysis and unconditional logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). Results: thirty-two of the 207 (15.5%) samples from farmers and 28 (18.4%) of the 152 samples from vendors tested positive for antimicrobial residues. Thirty-six (17.4 %) samples from farmers and 38 (25.0%) from vendors were found to be adulterated with water. Farmers' awareness of the danger of consuming milk with antimicrobial residues and farmers having training on good milking practices were protective against selling milk with antimicrobial residues (adjusted OR and 95% CI 0.20, 0.07-0.55 and 0.33, 0.11-0.99, respectively). Conclusion: the antimicrobial residues above EU MRLs and adulteration of raw marketed cow milk observed in this study provide evidence for routine testing of marketed milk and educating farmers to observe antimicrobial withdrawal period.

Preventive veterinary medicine, 2018

The camel milk trade in Kenya has evolved significantly from a small-scale business undertaken in... more The camel milk trade in Kenya has evolved significantly from a small-scale business undertaken in local villages to its current status involving a large number of different stakeholders supplying urban towns, particularly Nairobi City. Despite the evident growth pattern, the supply of camel milk to Nairobi has largely remained informal, with minimal enforcement of regulations. The aim of this study was to characterise the camel milk system supplying Nairobi and assess its governance, main challenges and the potential food safety risk practices. A value chain analysis framework was used to carry out data collection between August 2014 and July 2015. Qualitative and quantitative data were collected through focus group discussions and key informant interviews with stakeholders operating in different nodes of the value chains. Three milk value chains supplying Nairobi were identified and mapped: the Isiolo chain, the Kajiado chain and the camel milk processing company chain. Overall, th...

Tropical Animal Health and Production, 2015

A cross-sectional survey was conducted between the months of March 2014 and March 2015 to determi... more A cross-sectional survey was conducted between the months of March 2014 and March 2015 to determine the prevalence of contagious caprine pleuropneumonia in goat populations in pastoral flocks in three sub-counties of the Rift Valley region. A total of 432 serum samples were collected from goats from 54 flocks and tested for the presence of antibodies against mycoplasma capricolum subspecies capripneumoniae (mccp) using monoclonal antibody-based competitive enzyme-linked immuno-sorbent assay. Sero-prevalence recorded for Turkana West was 63.9 %, Kajiado Central was 48.6 %, while Pokot East was 29.2 % which was statistically significant (χ2 = 34.997; P = 0.000) in the study sites. The results of this study confirmed that CCPP is widespread and endemic in the pastoral production systems studied in the Rift Valley region. The results confirmed that regions sharing international boundaries are at a higher risk of CCPP hence the need for a unified cross-border approach to disease control measures in the border areas.

This study evaluated a direct multiplex PCR to detect food contamination with enterotoxigenic Bac... more This study evaluated a direct multiplex PCR to detect food contamination with enterotoxigenic Bacillus cereus (B. cereus) in comparison with culture and multiplex gene detection using colonies. Detection of B. cereus enterotoxin genes was done on artificially contaminated and ready-to- eat market foods including cooked rice, pasteurized milk and cheese. Of the 108 food samples analysed, 51(47.2 % were found

This study characterises enterotoxin genes including nheA, nheB, nheC, hblA, hblC, hblD, entFM,cy... more This study characterises enterotoxin genes including nheA, nheB, nheC, hblA, hblC, hblD, entFM,cytK, bceT, and ess in 51 Bacillus cereus (B. cereus) strains isolated from pasteurized milk, processed cheese and cooked rice. A colony multiplex polymerase chain reaction was used to test for presence of genes in B. cereus isolates. Of the fifty one B. cereus isolates, 12 (33.3%) were from milk, 8 (22.2%) from cheese and 31 (60.7%) from rice. The isolates were classified into 15 toxigenic groups A - O according to the genes they contained. Group G had the highest number of strains, 8(15.7%) while groups D and H had one isolate each. The emetic toxin gene sequence (ess) was found in 18% while bceT was found in 20% of rice isolates. The cytK gene was present in 4% of milk and 8% of rice isolates. The cytK gene was not found in any of the cheese isolates. All the other genes were found in isolates from all the three food types. The toxigenic profiles of isolates from milk and cheese differe...

Tropical Animal Health and Production, 2012

The objective of the study was to investigate and assess the impact of trainings on the levels of... more The objective of the study was to investigate and assess the impact of trainings on the levels of meat contamination produced from local livestock slaughter facilities in the NorthWest region of Somalia (Somaliland). The investigation considered slaughter facilities where workers had been trained or not. The survey was carried out in four local slaughter facilities. A pre-tested questionnaire on abattoir hygiene and food safety standards was administered to International Aid Organizations, government officials, abattoir workers and supervisors. In addition, a total of 320 surface meat swab samples were collected from randomly selected small ruminant carcasses slaughtered from four purposefully selected local slaughter facilities. The samples were analyzed at Analabs laboratories in Nairobi, Kenya, for total viable counts, total coliforms count and presence of Salmonella species. Meat contamination risk factors associated with hygiene practices based on training offered or not was identified. It was noted that slaughter facilities where abattoir workers had not received trainings on minimum meat hygiene standards and quality assurance systems of good hygiene practices and sanitary standard operating procedures produced carcasses with high levels of bacterial contamination in comparison with those where workers had received the said trainings. The laboratory results were in agreement with poor hygiene meat handling practices and lack of compliance with minimum meat hygiene and food safety standards in Berbera and Burao local livestock slaughter facilities where personnel had not been trained.

FEMS Microbiology Letters, 2006

Microbial Drug Resistance, 2007

The aims of this study were to determine the genetic basis of streptomycin and chloramphenicol re... more The aims of this study were to determine the genetic basis of streptomycin and chloramphenicol resistance in 30 Escherichia coli isolates from food animals in Kenya and the role of plasmids in the spread of the resistance. Seven of the 29 streptomycin-resistant isolates harbored both the strA and strB genes. Twenty-one of isolates had the strA, strB, and aadA1 genes. The strA gene was disrupted by a functional trimethoprim gene, dfrA14 in 10 of the 21 isolates harboring the three streptomycin resistance genes. Physical linkage of intact strA and sul2 genes was found in two different plasmids from four isolates. Linkage of cassette-borne aadA1 and dfrA1 genes in class 1 integrons was found in two of the isolates. Chloramphenicol resistance was due to the gene catA1 in all the chloramphenicol resistant isolates. The strB, strA, and catA1 genes were transferable by conjugation and this points to the significance of conjugative resistance plasmids in the spread and persistence of streptomycin and chloramphenicol resistance in food animals in Kenya.