Antibacterial Effect of Some Plant Extracts on Selected Enterobacteriaceae

Vernonia amygdalina (Bitterleaf), Eucalyptus citriodora (Eucalypt) and Phyllanthus amarus (Schum) were investigated for their antibacterial properties against pure cultures of clinical isolates of Escherichia coli, Klebsiella sp., Salmonella sp. and Shigella sp. The isolates were obtained from dept of Medical Microbiology and Parasitology of the University of Ilorin Teaching Hospital. Water and Ethanol were used in the crude extractions of the active constituents of the plants. Broth dilution and Agar diffusion methods were used in determining the antibacterial effects of the different plant extracts on the test organisms. The minimum inhibitory concentration (MIC) of the water extracts on the test organisms was 50 mg/ml while that of the ethanolic extract ranged between 6.25 - 50 mg/ml. Similarly the diameters of zones of inhibition of the plant extracts at concentration of 100 mg/ml ranged between 3.0-14.0 mm and 3.0-18.0 mm for the water and ethanolic extracts respectively on the test organisms. Water extracts of vernonia amygdalina (Bitterleaf) and Schum (Phyllanthus amarus) were not effective on majority of the test organisms. Klebsiella sp. was not inhibited by the water extracts at the test concentrations. The Ethanolic extracts of Eucalyptus citriodora (Eucalypt) were most effective on all the test organisms. The least and the most susceptible organisms to the extracts were Shigella sp. and E. coli respectively. The results of this study suggest the possibility of using the ethanolic extracts of these plants in treating diseases caused by the test organisms

Tradomedical Values of Cotton Leaf Plus Lemon Juice Against Clinical Bacterial Isolates

The antibacterial activity of the water and ethanolic extracts of cotton leaf (Gossypium spp.) plus lemon juice (Citrus limon) were tested against pure clinical isolates of Salmonella sp., Shigella sp., E. coli and Klebsiella sp. Cotton leaf is normally used in conjunction with lemon juice by the local populace in Nigeria for the treatment of enteric infections. Decoction method was used for the extraction of the active components from the plant in order to simulate the traditional method of extraction. The Minimum Inhibitory Concentration (MIC) and the diameters of zones of inhibition were determined by broth dilution and Agar diffusion methods respectively. The ethanolic extracts are more effective than the water extracts on the test organisms. The MIC of the water and ethanolic extracts ranged between 1.25 -5.0 w/v on the test organisms. Similarly, the average diameter of zones of inhibition of the water extracts on the test organisms ranged between 3.0 to 13.0mm while that of the ethanolic extracts ranged between 12.0 to 21.0mm. The results of this study showed that E. coli was the most susceptible followed by Klebsiella sp., then Salmonella sp., and finally Shigella sp. at the concentrations used for both water and ethanolic extracts. This observation thereby justifies the traditional uses of these plant extracts among the Nigerian local populace for the treatment of some enteric infections such as dysentery and diarrhoea

Antibacterial effect of Ocimum gratissimum against bacteria from paediatric diarrhoeal stool samples in the tropics

The upsurge in the prevalence of side effects of many synthetic antimicrobial agents and incidence of multidrug resistant bacteria has spurred scientists on the research for plant based antimicrobial of therapeutic potentials. Ocimum gratissimum presents such potential of high medicinal value. This plant is used in Nigeria traditionally as condiments and for the treatment of various ailments such as pyorrhea, dysentery and bronchitis. Aqueous and ethanolic leaf extracts of O. gratissimum was screened for antibacterial activity against bacteria recovered from paediatric diarrhoea stool samples. Both extracts were found to exhibit selective inhibition against the isolates. The diameter zones of inhibition exhibited by the extracts were between 2.50±0.50mm – 26.00±1.00mm. The ethanolic and aqueous extracts had minimum inhibitory concentrations that ranged between 15 and 25mg/ml, the extracts were bacteriostatic. Ethanolic extract showed more inhibitory effects compared to the aqueous extracts. The phytochemical analysis of both extracts revealed the presence of saponins, alkaloids, flavonoids, phenolics, tannins and glycosides, volatile oils, proteins and amino acids and terpernoids. In view of the efficacy of these extracts in inhibiting the growth of diarrhoea- causing organisms in paediatric stool samples, the utilization of the extracts in the formulation of new antibacterial drugs for the treatment of gastroenteritis caused by these organisms is strongly recommended especially when the availability and low cost of this medicinal plant are put into strong consideration.Keywords: Ocimum, diarrhoea, paediatric, stool, antibacteria

Biofilm-forming bacteria and their antibiotic resistance in treated water supplies in Ilorin Metropolis, Nigeria

Several water-related disease outbreaks have been attributed to deficiencies in water distribution systems (WDS). This study determined the relationship between biofilm-producing bacteria and their antibiotic resistance in WDS in Ilorin Metropolis, Nigeria through the assessment of the quality of water, the virulence factors possessed and susceptibility to some antibiotics. The physicochemical and bacteriological quality of the water samples were analyzed using standard methods. A total of 60 samples were collected from seven different locations within Ilorin metropolis. The pH of the water samples ranged from 6.58 – 7.22, turbidity 0.14 – 2.07 NTU and free residual chlorine ranged from 0.00 – 1.14 mg/L. A total of eleven bacteria isolates were identified by biochemical and molecular methods. They included genera of Pseudomonas, Escherichia, Staphylococcus, Klebsiella, Citrobacter, Shigella, Proteus, Yersinia and Serratia. The total bacterial counts were 1.10 – 7.20 × 102 cfu/mL. The isolates consisted of 72.7% biofilm producers using the tube method and 63.6% biofilm producers using the congo red method. Both biofilm and non-biofilm isolates displayed complete resistance to ceftriazone, amoxicillin, tetracycline, and cotrimoxazole. Biofilm producers showed stronger relationship with antibiotic resistance (p < 0.0001) than non-biofilms, thus suggesting the use of bacterial biofilm counts as indicators of water quality

Antibacterial activity of honey (<em>Apis mellifera</em>) on <em>Pseudomonas aeruginosa, Klebsiella pneumonia</em> and <em>Escherichia coli</em> isolated from wastewater

The use of honey as a remedy for microbial infections has been the reason behind recent researches on its antimicrobial activity. The research assessed the antibacterial activity of honey on Eschericia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae isolated from environmental wastewater, using disc diffusion method at various concentrations of honey ranging from 62.5 - 1000 mg/ml while the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined using macro-dilution method. The zones of inhibition across the disc were measured after 24 hours of incubation. Results showed that honey has higher antibacterial activity on E. coli compared to other test isolates and also higher on E. coli than ciprofloxacin. Honey showed weaker activity on K. pneumoniae and P. aeruginosa compared to standard antibiotics. MIC was 250 mg/ml for E. coli while K. pneumoniae and P. aeruginosa were at 500 mg/ml. MBC for E. coli, K. pneumoniae and P. aeruginosa were observed at 312. 5 mg/ml, 687.5 mg/ml and 750 mg/ml respectively. Honey has promising antibacterial activity on infections caused by E. coli, K. pneumoniae and P. aeruginosa because of its antibacterial properties such as low pH, high osmolarity, and production of hydrogen peroxide

Spatial Assessment of Public Water Supplies in Densely Populated Areas of Ilorin Metropolis, Kwara State, Nigeria

Water samples collected from public tap supplies at densely populated areas within Ilorin metropolis were analyzed for potability and safety. The study covered a period of twenty-four months. Physicochemical parameters such as pH, turbidity, residual chlorine, colour, suspended solids and total hardness were determined. The pH of the samples ranged from 7.0 - 7.90 while the range for residual chlorine was 0.5 - 10 mg/L. The suspended solids and total hardness ranged from 0.79 - 46.0 mg/L and 7.0 - 34mg/L respectively. Turbidity of the samples ranged from 0 – 5 NTU, while the colour range was 0 - 5 HU and temperature range was 21 - 30 0C. The results show that only four (20%) of the twenty samples were potable and free from pathogens while Escherichia coli, Klebsiella sp., Salmonella sp., Pseudomonas aeruginosa, Shigellla sp. and Enterobacter aerogenes were detected in sixteen (80%) of the samples. The viable total bacterial count ranged between 0.00 – 2.6 x 102 cfu/mL, total coliform count ranged from 0 – 75 MPN/100mL while faecal coliform count ranged from 0.00 – 2.3 x 102 cfu/mL. The presence of coliforms in the samples is indicative of faecal and non-faecal contamination along the supply network, which in some cases could be due to leaching from contaminated environment into corroded pipes along the distribution network used for conveying the treated water that passed through drainage system. Keywords: Coliforms, contamination, safety, bacteriological, physicochemical parameter

Microbial Deterioration of Tomato Fruit ( Lycopersicon esculentum ) Sold in Three Popular Markets in Ilorin, Kwara State, Nigeria

The economic loss as a result of spoilage and proliferation of microorganisms on tomato fruits with the possible health risks were the justification for this study. One hundred and fifty tomato fruit samples in different stages of spoilage from three different markets in Ilorin, Kwara State, Nigeria were collected within five weeks and the effect of moisture content on each sample and resulting microflora examined. The pH of the samples ranged from 4.90 - 5.40, while the moisture content ranged from 89.10% - 90.70%. The bacteria counts ranged from 4.00 x 106 - 7.50 x 106 cfu/ml, while the fungal counts ranged from 1.60 x 106 - 3.50 x 106 cfu/ml. A total number of sixteen bacteria and eleven fungi including yeasts were associated with the samples. The bacterial isolates included Aeromonas veronii, Bacillus sp., Neisseria sp., Corynebacterium renale, Pseudomonas fluorescens, Micrococcus varians, Moraxella sp., Bacillus polymyxa, Aeromonas hydrophila, Pseudomonas sp., Bacillus megaterium, Corynebacterium ulcerans, Vibrio sp., Proteus mirabilis, Corynebacterium xerosis, and Bacillus brevis while the fungal isolates included Alternaria sp., Botrytis sp., Candida albicans, Candida guilliermondii, Candida tropicalis, Chrysosporium tropicum, Curvularia sp., Doratomyces microsporus, Geotrichum candidum, Saccharomyces cerevisiae, and Rhizopus stolonifer. The high moisture content of the tomato samples provides an enabling environment for proliferation of the microbial load and hence its spoilage and potential to become health risk to human beings. Keywords: Spoilage, proliferation, economic loss, pH and moistur

Optimization of Conditions for Xylanase Production Using Aspergillus tubingensis Under Different Carbon Sources

Xylanases are hydrolytic enzymes with wide range of applications in food processing, bleaching of pulp in paper manufacturing industry, bio-conversion of biomass wastes to fermentable sugars and enhancing nutrient digestibility in animal feeds. The optimization of growth conditions and evaluation of an appropriate substrate as carbon source among cassava peels, corn cobs, wheat bran and rice husk on xylanase production by novel strain of Aspergillus tubingensis under Solid State Fermentation (SSF) was investigated. The fungal isolate was identified based on ribosomal RNA gene and ITS gene sequencing analysis as Aspergillus tubingensis. Results showed that Corn cobs had the highest xylanase production among the four substrates. Corn cobs recorded the highest value of xylanase production at pH of 6.0 (107.97 U/g), after incubation period of 72 hour (111.23 U/g), at temperature of 30 oC (44.26 U/g) and at ratio 1:3 (45.68 U/g). The optimum growth conditions for xylanase production by Aspergillus tubingensis were: pH 6.0, incubation period of 72 hours, temperature of 30 oC and substrate concentration of 1:3 (4g of substrate per 12mL of fermentation medium). Corn cobs showed the highest yield of xylanase activity (111.23±0.31 U/g), followed by Rice husk (101.91±0.72 U/g), Wheat bran (89.30±1.16 U/g) and Cassava peel (87.03±0.57 U/g). In conclusion, among the various agro residues that were used as carbon sources, Corn cobs had maximum xylanase activity. Various culture conditions were optimized by using one factor at a time method and the maximum xylanase production was obtained at pH of 6.0, incubation period of 72 hour, temperature of 30 oC and substrate concentration of 1:3 under solid state fermentation. It is therefore suggested that some other notable environmental and fermentation factors that influence metabolism-mediated production yields of xylanase like aeration, agitation, carbon and nitrogen sources, metal ion requirement,  inoculum size etc. should be optimized for maximum production of enzyme. Keywords: Solid State Fermentation, Cassava peels, Corn cobs, Wheat bran, Rice hus

Antibacterial Efficacies of Extracts of Lemon Grass (Cymbopogon citratus) on Some Clinical Microbial Isolates

The spread of new infections and the emergence of multidrug resistant strains of microorganisms necessitate the search for new antimicrobials with focus on plant extracts. In this study, the antimicrobial activity of the extracts (aqueous and ethanolic) of lemon grass known usually for bioactive essential oil (Cymbopogon citratus) was investigated in-vitro, against selected clinical isolates (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans). Antimicrobial efficacy of the extracts was assessed using the agar-well diffusion and broth-dilution techniques. The aqueous extract of C. citratus was more efficacious as it showed higher antimicrobial activity against all the test isolates at all tested concentrations. In contrast, only two of the test isolates; P. aeruginosa and S. aureus were susceptible to the ethanolic extract with minimum inhibitory (MIC) concentrations of 2 mg/mL (against S. aureus) and 12.5 mg/mL (against P. aeruginosa). The MIC of the aqueous extract were (mg/mL): 2, 6.25, 12.5, 25 and 50 against S. aureus, E. faecalis, P. aeruginosa, E. coli and C. albicans respectively. Meanwhile, both the aqueous and ethanolic extracts of C. citratus exerted only a bacteriostatic effect against the five test isolates at all concentrations. Quantitative phytochemical screening of the two extracts revealed the presence of more concentration of active compounds in the aqueous extract than the ethanolic extract which plausibly accounts for its greater antimicrobial activity. This study has shown that, in difference to the use of its conventional essential oil, solvent extraction of Cymbopogon citratus is also a potent source of efficacious antimicrobials. Further works to determine the respective mechanisms of action(s) of the extracts’ active principle is being projected.  Keywords: Lemon grass, Clinical isolates, Antimicrobial efficacies, Bioactive compounds