Antimicrobial Activity of Tamarindus indica Linn

Purpose: Tamarindus indica is a plant that is used in traditional medicine for the treatment of cold, fever, stomach disorder, diarrhea and jaundice and as skin cleanser. To evaluate the scientific basis for the use of the plant, the antimicrobial activities of extracts of the stem bark and leaves were evaluated against some common gram negative and gram positive bacteria and fungi. The study also investigated the chemical constituents of the plant and the effect of temperature and pH on its antimicrobial activity. Methods: The phytochemical constituents of the dried powdered plant parts were extracted using aqueous and organic solvents (acetone and ethanol). The antimicrobial activity of the concentrated extracts was evaluated by determination of the diameter of zone of inhibition against both gram negative and gram positive bacteria and fungi using the paper disc diffusion method. Results: Results of the phytochemical studies revealed the presence of tannins, saponins, sesquiterpenes, alkaloids and phlobatamins and the extracts were active against both gram positive and gram negative bacteria. The activity of the plant extracts were not affected when treated at different temperature ranges (4oC, 30oC, 60oC and 100oC), but was reduced at alkaline pH. Studies on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts on the test organisms showed that the lowest MIC and the MBC were demonstrated against Salmonella paratyphi, Bacillus subtilis and Salmonella typhi and the highest MIC and MBC was exhibited against Staphylococcus aureus. Conclusions: Tamarindus indica has broad spectrum antibacterial activity and a potential source of new classes of antibiotics that could be useful for infectious disease chemotherapy and control. Keywords: Tamarindus indica, Antimicrobial activity, minimum inhibitory concentration, minimum bactericidal concentration, chemotherapy, infectious disease. > Tropical Journal of Pharmaceutical Research Vol. 5 (2) 2006: pp. 597-60

Production of β-glucanase enzyme from Penicillium oxalicum and Penicillium citrinum

Two Penicillium species namely, Penicillium oxalicum and Penicillium citrinum cultivated by solid surface fermentation method using rice bran homogenized with 0.5% (w/v) (NH4)2SO4 solution as nitrogen source and Whatman no. 1 filter paper (WFP1) as substrate for β-glucanase enzyme production medium were found to show a dense growth. Studies on the enzyme, using soluble cellulose (SC) and methyl cellulose (MC) as cellulose-glucan source and Somogyi titrimetric method, revealed optimum temperature for enzyme activity from the Penicillium species, ranging from 50 to 55°C and thermostability of up to 70°C after 15 to 30 min incubation in sodium phosphate buffer. It was found that the metal ions (0.5 to 5.0 M) namely: Zn2+, Cu2+ and Hg2+ did not enhance β-glucanase activity. Cu2+ ions reduced the enzyme activity slightly, Zn2+ ions had no effect, while Hg2+ completely inhibited β-glucanase activity. β-Glucanase can be produced from some fungal species locally using the abundant agricultural wastes (such as rice bran) as substrates.Key words: Fermentation, methylcellulose, metal inhibitors, soluble cellulose, Penicillium species

Antibacterial effects of Balanites aegyptiaca L. Drel. and Moringa oleifera Lam. on Salmonella typhi

The aqueous and organic leaves extracts of Balanites aegyptiaca and Moringa oleifera traditionally used for the treatment of infectious disease were tested for their activity against Salmonella typhiisolated from blood clot culture using the disc diffusion method. Extracts of B. aegyptiaca demonstrated higher activity (16 mm zone of inhibition) than those of Moringa oleifera (8 mm zone ofinhibition) at 100 mg/ml. Of the three solvents used, ethanolic extracts of both plants demonstrated the highest activity, while the aqueous extracts showed the least activity at 100 mg/ml. The activities ofthese plant extracts were comparable to those of antibiotics, ciprofloxacin, cotrimoxazole and chloramphenicol, commonly used for treating typhoid fever. The antibacterial activity appears toincrease when extracts of the two plants were used in combination at 100 mg/ml each (18 mm zone of inhibition). Preliminary phytochemical screening showed that both plant extracts contains saponins,tannins and phenols while only M. oleifera possesses alkaloids and B. aegyptiaca possesses anthraquinones. The antibacterial activities of the extracts on S. typhi was reasonably stable when treated at 4, 30, 60 and 100oC for 1 h, however it reduces significantly when the pH was altered towards alkalinity

Efficacy of low-pressure foam cleaning compared to conventional cleaning methods in the removal of bacteria from surfaces associated with convenience food

Published ArticleFood borne illnesses and food poisoning are cause for concern globally. The diseases are often caused by food contamination with pathogenic bacteria due largely to poor sanitary habits or storage conditions. Objectives: Prevalence of some bacteria on cleaned and sanitised food contact surfaces from eight convenience food plants in Gauteng (South Africa) was investigated with the view to evaluate the efficacy of the cleaning methods used with such food contact surfaces. Methods: The microbial load of eight convenience food manufacturing plants was determined by sampling stainless steel food contact surfaces after they had been cleaned and sanitised at the end of a day’s shift. Samples were analysed for Total Plate Count (TPC), Escherichia coli, Salmonella species, Staphylococcus aureus and Listeria species. Results: Results showed that 59 % of the total areas sampled for TPC failed to comply with the legal requirements for surfaces, according to the Foodstuffs, Cosmetics and Disinfectants Act ( 0.05) in terms of Listeria species isolates obtained from both cleaning methods. The LPF method proved to be the superior cleaning option for lowering TPC counts. Conclusion: Regardless of cleaning method used, pathogens continued to flourish on various surfaces, including dry stainless steel, posing a contamination hazard for a considerable period depending on the contamination level and type of pathogen. Intensive training for proper chemical usage and strict procedural compliance among workers for efficient cleaning procedures is recommended

Bacterial contamination of the hands of food handlers as indicator of hand washing efficacy in some convenient food industries

Published ArticleHands of ready-to-eat food service employees have been shown to be vectors in the spread of foodborne disease, mainly because of poor personal hygiene and accounting for approximately 97% of food borne illnesses in food service establishments and homes. Our objective was to evaluate the efficacy of hand washing practices and sanitation before commencing work among food handlers in the convenient food industry in Gauteng, South Africa. Methods: A total of 230 samples were collected, involving 100% of the food handlers, in 8 selected convenient food outlets with their main focus on preparing ready-to-eat foods. The workers’ cleaned and disinfected dominant hands were sampled for Total Plate Count (TPC), Staphylococcus aureus and Escherichia coli. Bacteria were isolated and counted using standard methods. Results: The highest bacterial count from the hand samples was 7.4 x 103 cfu.cm-2 and the lowest showed no detectable growth. Although hands with a count of 0 cfu.cm-2 were found in all of the plants, the results indicated that all the plants exceeded the legal limit for food surfaces or hands of < 100 cfu.cm-2 when the average bacterial counts on hands were compared. Sixty percent of the TPC analysed exceeded the legal limit and only 18% of the food handlers had no bacteria detectable on their hands. One sample tested positive for E. coli and S. aureus could not be detected on the hands of any of the food handlers. Conclusion: The study revealed that hand hygiene is unsatisfactory and may have serious implications for public health due to contamination of food from food handlers’ hands. This therefore underlined the importance of further training to improve food handlers’ knowledge of good hand washing practices

Virulence factors and antibiotic susceptibility among verotoxic non O157: H7 Escherichia coli isolates obtained from water and wastewater samples in Cape Town, South Africa.

Forty eight samples (30 wastewater and 18 river water) were collected between July and November, 2010, from different sources in Cape Town, South Africa in order to characterize verotoxic non O157: H7 Escherichia coli strains. Samples (1 ml) were inoculated into MacConkey broth (MB, 9 ml) and incubated at 37°C for 24 h, after which a loopful of the MB was then spread onto Eosin Methylene Blue (EMB) and further incubated for 24 h at 37°C in order to isolate E. coli. The identification of isolates was done using standard biochemical procedures; and confirmed serologically using E. coli polyvalent antisera (Bioweb, SA). Isolates were also characterized for virulence factors such as verotoxin, haemolysin, gelatinase, extended spectrum beta lactamases (ESBLs), cell surface hydrophobicity and bacterial serum resistance, as well as susceptibility (using disc diffusion method) to stem bark extracts of Curtisia dentata. Results showed the presence of different serotypes of E. coli (69 isolates in all) including 026: H11, 055, O111: NM, O126, O44, O124, O96:H9, O103:H2, O145: NM and O145:H2. Over 60% of the isolates exhibited serum resistance, haemolysin and gelatinase production, 81% exhibited cell surface hydrophobicity and over 52% produced ESBLs. Results also showed that while 60% of the isolates showed various levels of resistance to different antibiotics [ampicillin (10 μg), cefuroxime, cephalexin, ceftazidime and tetracycline (30 μg in each case) (multidrug resistance index (MDRI) values 4.20 to 5.60%)], only 28% were resistant to ethanol stem bark extracts of C. dentata (MIC, 70 to 150 mg/ml). The presence of pathogenic verotoxic antibiotic resistant E. coli in these water sources is a threat to water quality and food security and C. dentata has a potential for sourcing novel antibiotic substances for chemotherapy against these resistant pathogenic strains of E. coli.Key words: Curtisia dentata, Escherichia coli, haemolysins, cell surface hydrophobicity, gelatinase, plant extracts, verotoxins

Impact of effluent from gudu district sewage treatment plant on gudu stream in Abuja, Nigeria.

Gudu stream, the major stream providing water for Durumi 1, Durumi 2 and Durumi 3 settlements of Gudu District in Abuja, Nigeria was studied for impact assessment of discharged effluent from the Gudu District wastewater treatment plant. Studies on the physicochemical properties of the stream revealed high concentration of contaminants at the point of effluent discharge (IP) and upstream (USP). The effluent had no effect on the temperature of the stream at all points sampled (27\ub0C). Bacteriological analysis revealed the most probable number (MPN) to be highest at USP ( 651800/100ml) and EP ( 651700/100ml), followed by that of DSP (1000/100ml) and the least value was obtained at IP (750/100ml). Escherichia coli , Salmonella typhi , S. paratyphi, Shigella flexnerri Klebsiella spp and Pseudomonas aerugenosa . Escherichi coli, Salmonella typhi, S. paratyphi, Shigella flexnerri were the prevalent bacteria isolated at all the points sampled