Abstract: Background: An outbreak of gastroenteritis occurred in December 2019 after students of a Senior High School in Accra were served with kenkey and fish during their dinner. An investigation was conducted to characterize the affected people, the source of contamination, the etiologic food and agent. Methods: An epidemiological study was conducted with cases selected from the student population who were ill. Controls were selected from among students who also ate from the school canteen during dinner but were not ill. Food history of each case and control was taken to assess their exposure status. Epi Info 7 was used to analyze the data obtained from the outbreak. Attack rates and odds ratios were calculated to determine the risk of foodborne infection for each of the foods consumed by the population. The source of contamination of the foods was ascertained by conducting an environmental risk assessment at the school. Results: Data were obtained from 126 students, out of which 57 (45.2%) were cases and 69 (54.8%) were controls. The cases presented with symptoms such as diarrhea (85.96%), abdominal cramps (66.67%), vomiting (50.88%), headache (21.05%), fever (17.86%) and nausea (3.51%). The peak incubation period was 18 hours with a minimum and maximum incubation periods of 6 and 50 hours respectively. From the incubation period, duration of illness and the symptoms, non-typhoidal salmonellosis was suspected. Multivariate analysis indicated that the illness was associated with the consumption of the fried fish served, however this was statistically insignificant (AOR 3.1.00, P = 0.159). No stool, blood or food samples were available for organism isolation and confirmation of suspected etiologic agent. The environmental risk assessment indicated poor hand washing practices on the part of both the food handlers and students. Conclusion: The outbreak could probably be due to the consumption of the fried fish that might have been contaminated with Salmonella sp. as a result of poor hand washing practices in the school.
Abstract: This study presents the synthesis of a series of methoxybenzoylthiourea amino acid derivatives. The compounds were obtained from the reactions between 2/3/4-methoxybenzoyl isothiocyanate with threonine. All of the compounds were characterized via mass spectrometry, 1H and 13C NMR spectrometry, UV-Vis spectrophotometer and FT-IR spectroscopy. Mass spectra for all of the compounds showed the presence of molecular ion [M]+ peaks at m/z 312, which are in agreement to the calculated molecular weight. For 1H NMR spectra, the presence of OCH3, C=S-NH and C=O-NH protons were observed within range of δH 3.8-4.0 ppm, 11.1-11.5 ppm and 10.0-11.5 ppm, respectively. 13C NMR spectra in all compounds displayed the presence of OCH3, C=O-NH, C=O-OH and C=S carbon resonances within range of δC 55.0-57.0 ppm, 165.0-168.0 ppm, 170.0-171.0 ppm and 180.0-182.0 ppm, respectively. In UV spectra, two absorption bands have been observed and both were assigned to the n-π* and π-π* transitions. Six vibrational modes of v(N-H), v(O-H), v(C=O-OH), v(C=O-NH), v(C=C) aromatic and v(C=S) appeared in the FT-IR spectra within the range of 3241-3467 cm-1, 2976-3302 cm-1, 1720-1768 cm-1, 1655-1672 cm-1, 1519-1525 cm-1 and 754-763 cm-1, respectively. The antibacterial activity for all of the compounds was screened against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella typhimurium and Escherichia coli. However, no activity was observed.
Abstract: Food safety is a significant and growing public health problem in the world and Nigeria as a developing country, since food-borne diseases are important contributors to the huge burden of sickness and death of humans. In Nigeria, traditional ready-to-eat meat products (RTE-MPs) like balangu, tsire, guru and dried meat products like kilishi, dambun nama, banda, were reported to be highly appreciated because of their eating qualities. The consumption of these products was considered as safe due to the treatments that are usually involved during their production process. However, during processing and handling, the products could be contaminated by pathogens that could cause food poisoning. Therefore, a hazard identification for pathogenic bacteria on some traditional RTE-MPs was conducted in Kebbi and Sokoto States, Nigeria. A total of 116 RTE-MPs (balangu-38, kilishi-39 and tsire-39) samples were obtained from retail outlets and analyzed using standard cultural microbiological procedures in general and selective enrichment media to isolate the target pathogens. A six-fold serial dilution was prepared and using the pour plating method, colonies were counted. Serial dilutions were selected based on the prepared pre-labeled Petri dishes for each sample. A volume of 10-12 ml of molten Nutrient agar cooled to 42-45°C was poured into each Petri dish and 1 ml each from dilutions of 102, 104 and 106 for every sample was respectively poured on a pre-labeled Petri plate after which colonies were counted. The isolated pathogens were identified and confirmed after series of biochemical tests. Frequencies and percentages were used to describe the presence of pathogens. The General Linear Model was used to analyze data on pathogen presence according to RTE-MPs and means were separated using the Tukey test at 0.05 confidence level. Of the 116 RTE-MPs samples collected, 35 (30.17%) samples were found to be contaminated with some tested pathogens. Prevalence results showed that Escherichia coli, salmonella and Staphylococcus aureus were present in the samples. Mean total bacterial count was 23.82×106 cfu/g. The frequency of individual pathogens isolated was; Staphylococcus aureus 18 (15.51%), Escherichia coli 12 (10.34%) and Salmonella 5 (4.31%). Also, among the RTE-MPs tested, the total bacterial counts were found to differ significantly (P < 0.05), with 1.81, 2.41 and 2.9×104 cfu/g for tsire, kilishi, and balangu, respectively. The study concluded that the presence of pathogenic bacteria in balangu could pose grave health risks to consumers, and hence, recommended good manufacturing practices in the production of balangu to improve the products’ safety.
Abstract: Background: Acute gastroenteritis is one of the frequently reported Out-Patient Department (OPD) cases. However, the causative pathogens of these cases are rarely identified at the OPD due to delay in laboratory results or failure to obtain specimens before antibiotics is administered. Method: A retrospective review of surveillance data from the Adentan Municipality, Accra, Ghana that were recorded in the National foodborne disease surveillance system of Ghana, was conducted with the main aim of describing the epidemiology and food practice of cases reported from the Adentan Municipality. The study involved a retrospective review of surveillance data kept on patients who visited health facilities that are involved in foodborne disease surveillance in Ghana, from January 2015 to December 2016. Results: A total of 375 cases were reviewed and these were classified as viral hepatitis (hepatitis A and E), cholera (Vibrio cholerae), dysentery (Shigella sp.), typhoid fever (Salmonella sp.) or gastroenteritis. Cases recorded were all suspected case and the average cases recorded per week was 3. Typhoid fever and dysentery were the two main clinically diagnosed foodborne illnesses. The highest number of cases were observed during the late dry season (Feb to April), which marks the end of the dry season and the beginning of the rainy season. Relatively high number of cases was also observed during the late wet seasons (Jul to Oct) when the rainfall is the heaviest. Home-made food and street vended food were the major sources of suspected etiological food, recording 49.01% and 34.87% of the cases respectively. Conclusion: Majority of cases recorded were classified as gastroenteritis due to the absence of laboratory confirmation. Few cases were classified as typhoid fever and dysentery based on clinical symptoms presented. Patients reporting with foodborne diseases were found to consume home meal and street vended foods as their predominant source of food.
Abstract: Herbal essential oil and extracts are a good source of natural antioxidants and antimicrobial compounds. Hypericum is one of the potential sources of these compounds. In this study, the antioxidant and antimicrobial activity of essential oil and aqueous, methanol, ethanol, ethyl acetate and acetone extract of Hypericum scabrum was assessed. Flowers of Hypericum scabrum were collected from the surrounding mountains of Hamadan province and after drying in the shade, the essential oil of the plant was extracted by Clevenger and water, methanol, ethanol, ethyl acetate and acetone extract was obtained by maceration method. Essential oil compounds were identified using the GC-Mass. The Folin-Ciocalteau and aluminum chloride (AlCl3) colorimetric method was used to measure the amount of phenolic acid and flavonoids, respectively. Antioxidant activity was evaluated using DPPH and FRAP. The minimum inhibitory concentration (MIC) and the minimum bacterial/fungicide concentration (MBC/MFC) of essential oil and extracts were evaluated against Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Salmonella typhimurium, Aspergillus flavus and Candida albicans. The essential oil yield of was 0.35%, the lowest and highest extract yield was related to ethyl acetate and water extract. The most component of essential oil was α-Pinene (46.35%). The methanol extracts had the highest phenolic acid (95.65 ± 4.72 µg galic acid equivalent/g dry plant) and flavonoids (25.39 ± 2.73 µg quercetin equivalent/g dry plant). The percentage of DPPH radical inhibition showed positive correlation with concentrations of essential oil or extract. The methanol and ethanol extract had the highest DDPH radical inhibitory. Essential oil and extracts of Hypericum had antimicrobial activity against the microorganisms studied in this research. The MIC and MBC values for essential oils were in the range of 25-25.6 and 25-50 μg/mL, respectively. For the extracts, these values were 1.5625-100 and 3.125-100 μg/mL, respectively. Methanol extracts had the highest antimicrobial activity. Essential oil and extract of Hypericum scabrum, especially methanol extract, have proper antimicrobial and antioxidant activity, and it can be used to control the oxidation and inhibit the growth of pathogenic and spoilage microorganisms. In addition, it can be used as a substitute for synthetic antioxidant and antimicrobial compounds.
Abstract: In many countries, cow dung is used as farm manure and for biogas production. Several bacterial strains associated with cow dung such as Campylobacter, Salmonella sp. and Escherichia coli cause serious human diseases. The objective of the present study was to investigate the use of insect larvae including fruit beetle, waxworms and tiger worms to improve the breakdown of agricultural wastes and reduce their pathogen loads. Fresh cow faeces were collected from a cattle farm and distributed into plastic boxes (100 g/box). Each box was provided with 10 larvae of fruit beetle, Waxworms and Tiger worms, respectively. There were 3 replicates in each treatment including the control. Bacteria were isolated weekly from both control and cow faeces to which larvae were added to determine the bacterial populations. Results revealed that the bacterial load was higher in the cow faeces treated with fruit beetles than in the control, while the bacterial load was lower in the cow faeces treated with waxworms and tiger worms than in the control. The activities of the fruit beetle larvae led to the cow faeces being liquefied which provided a more conducive growing media for bacteria. Therefore, higher bacterial load in the cow faeces treated with fruit beetle might be attributed to the liquefaction of cow faeces.
Abstract: In recent years, tendency to use of natural antimicrobial agents in food industry has increased. Pomegranate peels containing phenolic compounds and anti-microbial agents, are counted as valuable source for extraction of these compounds. In this study, the extraction of pomegranate peel extract was carried out at different ethanol/water ratios (40:60, 60:40, and 80:20), temperatures (25, 40, and 55 ˚C), and time durations (20, 24, and 28 h). The extraction yield, phenolic compounds, flavonoids, and anthocyanins were measured. Antimicrobial activity of pomegranate peel extracts were determined against some food-borne microorganisms such as Salmonella enteritidis, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Aspergillus niger, and Saccharomyces cerevisiae by agar diffusion and MIC methods. Results showed that at ethanol/water ratio 60:40, 25 ˚C and 24 h maximum amount of phenolic compounds (349.518 mg gallic acid/g dried extract), flavonoids (250.124 mg rutin/g dried extract), anthocyanins (252.047 mg cyanidin3glucoside/100 g dried extract), and the strongest antimicrobial activity were obtained. All extracts’ antimicrobial activities were demonstrated against every tested microorganisms. Staphylococcus aureus showed the highest sensitivity among the tested microorganisms.
Abstract: The bioactivity studies from the weed ethanolic crude extracts from leaf, stem, pod and root of wild spider flower; Cleoma viscosa Linn. were analyzed for the growth inhibition of 6 bacterial species; Salmonella typhimurium TISTR 5562, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus TISTR 1466, Streptococcus epidermidis ATCC 1228, Escherichia coli DMST 4212 and Bacillus subtilis ATCC 6633 with initial concentration crude extract of 50 mg/ml. The agar well diffusion results found that the extracts inhibit only gram positive bacteria species; S. aureus, S. epidermidis and B. subtilis. The minimum inhibition concentration study with gram positive strains revealed that leaf crude extract give the best result of the lowest concentration compared with other plant parts to inhibit the growth of S. aureus, S. epidermidis and B. subtilis at 0.78, 0.39 and lower than 0.39 mg/ml, respectively. The determination of total phenolic compounds in the crude extracts exhibited the highest phenolic content was 10.41 mg GAE/g dry weight in leaf crude extract. Analyzed the efficacy of free radical scavenging by using DPPH radical scavenging assay with all crude extracts showed value of IC50 of leaf, stem, pod and root crude extracts were 8.32, 12.26, 21.62 and 35.99 mg/ml, respectively. Studied cytotoxicity of crude extracts on human breast adenocarcinoma cell line by MTT assay found that pod extract had the most cytotoxicity CC50 value, 32.41 µg/ml. Antioxidant activity and cytotoxicity of crude extracts exhibited that the more increase of extract concentration, the more activities indicated. According to the bioactivities results, the leaf crude extract of Cleoma viscosa Linn. is the most interesting plant part for further work to search the beneficial of this weed.
Abstract: Natural preservatives have been used as alternatives to traditional chemical preservatives; however, a limited number have been commercially developed and many remain to be investigated as sources of safer and effective antimicrobials. In this study, we have been investigating the antimicrobial activity of an extract of Glycyrrhiza glabra (liquorice) that was provided as a waste material from the production of liquorice flavourings for the food industry, and to investigate if this retained the expected antimicrobial activity so it could be used as a natural preservative. Antibacterial activity of liquorice extract was screened for evidence of growth inhibition against eight species of Gram-negative and Gram-positive bacteria, including Listeria monocytogenes, Listeria innocua, Staphylococcus aureus, Enterococcus faecalis and Bacillus subtilis. The Gram-negative bacteria tested include Pseudomonas aeruginosa, Escherichia coli and Salmonella typhimurium but none of these were affected by the extract. In contrast, for all of the Gram-positive bacteria tested, growth was inhibited as monitored using optical density. However parallel studies using viable count indicated that the cells were not killed meaning that the extract was bacteriostatic rather than bacteriocidal. The Minimum Inhibitory Concentration [MIC] and Minimum Bactericidal Concentration [MBC] of the extract was also determined and a concentration of 50 µg ml-1 was found to have a strong bacteriostatic effect on Gram-positive bacteria. Microscopic analysis indicated that there were changes in cell shape suggesting the cell wall was affected. In addition, the use of a reporter strain of Listeria transformed with the bioluminescence genes luxABCDE indicated that cell energy levels were reduced when treated with either 12.5 or 50 µg ml-1 of the extract, with the reduction in light output being proportional to the concentration of the extract used. Together these results suggest that the extract is inhibiting the growth of Gram-positive bacteria only by damaging the cell wall and/or membrane.
Abstract: One of the tasks in contemporary biotechnology, pharmacology and other fields of human activities is to obtain biologically active substances from plants. They are very essential in the treatment of many diseases due to their actually high therapeutic value without visible side effects. However, sometimes the possibility of obtaining the metabolites is limited due to the reduction of wild-growing plants. That is why the plant cell cultures are of great interest as alternative sources of biologically active substances. Besides, during the monitored cultivation, it is possible to obtain substances that are not synthesized by plants in nature. Isolated culture of Ajuga genevensis with high growth activity and ability of regeneration was obtained using MS nutrient medium. The agar-diffusion method showed that aqueous extracts of callus culture revealed high antimicrobial activity towards various gram-positive (Bacillus subtilis A1WT; B. mesentericus WDCM 1873; Staphylococcus aureus WDCM 5233; Staph. citreus WT) and gram-negative (Escherichia coli WKPM M-17; Salmonella typhimurium TA 100) microorganisms. The broth dilution method revealed that the minimal and half maximal inhibitory concentration values against E. coli corresponded to the 70 μg/mL and 140 μg/mL concentration of the extract respectively. According to the photochemiluminescent analysis, callus tissue extracts of leaf and root origin showed higher antioxidant activity than the same quantity of A. genevensis intact plant extract. A. genevensis intact plant and callus culture extracts showed no cytotoxic effect on K-562 suspension cell line of human chronic myeloid leukemia. The GC-MS analysis showed deep differences between the qualitative and quantitative composition of callus culture and intact plant extracts. Hexacosane (11.17%); n-hexadecanoic acid (9.33%); and 2-methoxy-4-vinylphenol (4.28%) were the main components of intact plant extracts. 10-Methylnonadecane (57.0%); methoxyacetic acid, 2-tetradecyl ester (17.75%) and 1-Bromopentadecane (14.55%) were the main components of A. genevensis callus culture extracts. Obtained data indicate that callus culture of A. genevensis can be used as an alternative source of biologically active substances.
Abstract: Fluoroquinolones form the mainstay of therapy for the treatment of infections due to Salmonella enterica subsp. enterica. There is a complex interplay between several resistance mechanisms for quinolones and various fluoroquinolones discs, giving varying results, making detection and interpretation of fluoroquinolone resistance difficult. For detection of fluoroquinolone resistance in Salmonella ssp., we compared the use of pefloxacin and nalidixic acid discs as surrogate marker. Using MIC for ciprofloxacin as the gold standard, 43.5% of strains showed MIC as ≥1 μg/ml and were thus resistant to fluoroquinoloes. Based on the performance of nalidixic acid and pefloxacin discs as surrogate marker for ciprofloxacin resistance, both the discs could correctly detect all the resistant phenotypes; however, use of nalidixic acid disc showed false resistance in the majority of the sensitive phenotypes. We have also tested newer antimicrobial agents like cefixime, imipenem, tigecycline and azithromycin against Salmonella spp. Moreover, there was a comeback of susceptibility to older antimicrobials like ampicillin, chloramphenicol, and cotrimoxazole. We can also use cefixime, imipenem, tigecycline and azithromycin in the treatment of multidrug resistant S. typhi due to their high susceptibility.
Abstract: Food poisoning and infection by bacteria are of public
health significance to both developing and developed countries.
Samples of ogi (akamu) prepared from white and yellow variety of
maize sold in Uturu and Okigwe were analyzed together with the
laboratory prepared ogi for bacterial quality using the standard
microbiological methods. The analyses showed that both white and
yellow variety had total bacterial counts (cfu/g) of 4.0 ×107 and 3.9 x
107 for the laboratory prepared ogi while the commercial ogi had 5.2
x 107 and 4.9 x107, 4.9 x107 and 4.5 x107, 5.4 x107 and 5.0 x107 for
Eke-Okigwe, Up-gate and Nkwo-Achara market respectively. The
Staphylococcal counts ranged from 2.0 x 102 to 5.0 x102 and 1.0 x
102 to 4.0 x102 for the white and yellow variety from the different
markets while Staphylococcal growth was not recorded on the
laboratory prepared ogi. The laboratory prepared ogi had no Coliform
growth while the commercially prepared ogi had counts of 0.5 x103
to 1.6 x 103 for white variety and 0.3 x 103 to 1.1 x103 for yellow
variety respectively. The Lactic acid bacterial count of 3.5x106 and
3.0x106 was recorded for the laboratory ogi while the commercially
prepared ogi ranged from 3.2x106 to 4.2x106 (white variety) and 3.0
x106 to 3.9 x106 (yellow). The presence of bacteria isolates from the
commercial and laboratory fermented ogi showed that Lactobacillus
sp, Leuconostoc sp and Citrobacter sp were present in all the
samples, Micrococcus sp and Klebsiella sp were isolated from Eke-
Okigwe and ABSU-up-gate markets varieties respectively, E. coli
and Staphylococcus sp were present in Eke-Okigwe and Nkwo-
Achara markets while Salmonella sp were isolated from the three
markets. Hence, there are chances of contracting food borne diseases
from commercially prepared ogi. Therefore, there is the need for
sanitary measures in the production of fermented cereals so as to
minimize the rate of food borne pathogens during processing and
storage.
Abstract: Medicinal plants are now gaining attractiveness in
treatment of bacterial infections and food preservation. The objective
of this study was to assess antibacterial activity of some medicinal
plants on pathogenic bacteria. Screening of antibacterial activity of
aqueous and methanol extracts of some plants: Jojoba, Ginger, Sage,
Thyme and Clove against Bacillus cereus, Salmonella typhimurium,
Staphylococcus aureus, Clostridium perfringens and Escherichia coli
were investigated. Antibacterial activity was performed by agar
diffusion and disc diffusion method. Jatropha, Jojoba, Clove and
Ginger extracts showed notable bacterial activity in the first
screening step then selected to be tested against Bacillus cereus
(Gram+), Staphylococcus aureus (Gram+) and Salmonella
typhimurium (Gram−) and their effect was compared using
antibiotics as control. Screening results showed potential antibacterial
activity of the tested plant extracts against the screened bacterial
strains. It was found that methanol extracts exhibited higher
antibacterial activity than aqueous extracts. Methanol extract of
Jatropha showed the highest inhibition zone against Staphylococcus
aureus (Gram+) with 24.00 mm diameter, compared to the other
plant extracts followed by clove. Meanwhile, the inhibition zones of
methanol extracts of Jojoba and Ginger were the same (12mm).The
Gram-positive bacteria were found to be more sensitive to aqueous
and methanol extracts than Gram-negative bacteria.
Abstract: Enterococci are important inhabitants of the animal
intestine and are widely used in probiotic products. A probiotic strain
is expected to possess several desirable properties in order to exert
beneficial effects. Therefore, the objective of this study was to
isolate, characterize and identify Enterococcus sp. from chicken cecal
and fecal samples to determine potential probiotic properties.
Enterococci were isolated from chicken ceca and feces of thirty three
clinically healthy chickens from a local farm. In vitro studies were
performed to assess antibacterial activity of the isolated LAB (using
agar well diffusion and cell free supernatant broth technique against
Salmonella enterica serotype Enteritidis), survival in acidic
conditions, resistance to bile salts, and their survival during simulated
gastric juice conditions at pH 2.5. Isolates were identified by
biochemical carbohydrate fermentation patterns using an API 50
CHL kit and API ZYM kits and by sequenced 16S rDNA. An isolate
belonging to E. faecium species exhibited inhibitory effect against S.
enteritidis. This isolate producing a clear zone as large as 10.30 mm
or greater and was able to grow in the coculture medium and at the
same time, inhibited the growth S. enteritidis. In addition, E. faecium
exhibited significant resistance under highly acidic conditions at pH
2.5 for 8 h and survived well in bile salt at 0.2% for 24 h and showing
ability to survive in the presence of simulated gastric juice at pH 2.5.
Based on these results, E. faecium isolate fulfills some of the criteria
to be considered as a probiotic strain and therefore, could be used as a
feed additive with good potential for controlling S. Enteritidis in
chickens. However, in vivo studies are needed to determine the safety
of the strain.
Abstract: Bacteria flora of Clarias gariepinus collected from two natural habitats namely Owena River (freshwater) and Igbokoda lagoon (brackish water) were examined using standard microbiological procedures. Thirteen bacterial species were identified. The result indicated that from the identified bacteria isolated, Vibrio sp, Proteus sp. Shigella sp. and E. coli were present in both habitats (fresh and brackish waters). Others were habitat-selective such as Salmonella sp., Pseudomonas sp, Enterococcus sp, Staphylococcus sp. that were found only in freshwater habitat. While Branhamella sp, Streptococcus sp. and Micrococcus sp. were found in brackish water habitat. Bacteria load from Owena river (freshwater) was found to be the highest load recorded at 6.21 x 104cfu. T-test analysis also revealed that there was a marked significant difference between bacterial load in guts of sampled Clarias from fresh water and brackish water habitats.
Abstract: Results of a field study carried out at Trinitapoli (Puglia region, southern Italy) on the irrigation of an artichoke crop with three types of water (secondary-treated wastewater, SW; tertiary-treated wastewater, TW; and freshwater, FW) are reported. Physical, chemical and microbiological analyses were performed on the irrigation water, and on soil and yield samples.
The levels of most of the chemical parameters, such as electrical conductivity, total suspended solids, Na+, Ca2+, Mg+2, K+, sodium adsorption ratio, chemical oxygen demand, biological oxygen demand over 5 days, NO3 –N, total N, CO32, HCO3, phenols and chlorides of the applied irrigation water were significantly higher in SW compared to GW and TW. No differences were found for Mg2+, PO4-P, K+ only between SW and TW. Although the chemical parameters of the three irrigation water sources were different, few effects on the soil were observed. Even though monitoring of Escherichia coli showed high SW levels, which were above the limits allowed under Italian law (DM 152/2006), contamination of the soil and the marketable yield were never observed. Moreover, no Salmonella spp. were detected in these irrigation waters; consequently, they were absent in the plants. Finally, the data on the quantitative-qualitative parameters of the artichoke yield with the various treatments show no significant differences between the three irrigation water sources. Therefore, if adequately treated, municipal wastewater can be used for irrigation and represents a sound alternative to conventional water resources.
Abstract: Gold nanoparticles (AuNPs) have gained increasing
interest in recent times. This is greatly due to their special features,
which include unusual optical and electronic properties, high stability
and biological compatibility, controllable morphology and size
dispersion, and easy surface functionalization. In typical synthesis,
AuNPs were produced by reduction of gold salt AuCl4 in an
appropriate solvent. A stabilizing agent was added to prevent the
particles from aggregating. The antibacterial activity of different
sizes of gold nanoparticles was investigated against Staphylococcus
aureus, Salmonella typhi and Pseudomonas pneumonia using the disk
diffusion method in a Müeller–Hinton Agar. The Au-NPs were
effective against all bacteria tested. That the Au-NPs were
successfully synthesized in suspension and were used to study the
antibacterial activity of the two medicinal plants against some
bacterial pathogens suggests that Au-NPs can be employed as an
effective bacteria inhibitor and may be an effective tool in medical
field. The study clearly showed that the Au-NPs exhibiting inhibition
towards the tested pathogenic bacteria in vitro could have the same
effects in vivo and thus may be useful in the medical field if well
researched into.
Abstract: The aim of the present work was to test in vitro inhibition of food pathogens and spoilage bacteria by crude bacteriocins from autochthonous lactic acid bacteria. Thirty autochthonous lactic acid bacteria isolated previously, belonging to the genera: Lactobacillus, Carnobacterium, Lactococcus, Vagococcus, Streptococcus, and Pediococcus, have been screened by an agar spot test and a well diffusion assay against Gram-positive and Gram-negative harmful bacteria: Bacillus cereus, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 8739, Salmonella typhimurium ATCC 14028, Staphylococcus aureus ATCC 6538, and Pseudomonas aeruginosa under conditions means to reduce lactic acid and hydrogen peroxide effect to select bacteria with high bacteriocinogenic potential. Furthermore, crude bacteriocins semiquantification and heat sensitivity to different temperatures (80, 95, 110°C, and 121°C) were performed. Another exploratory test concerning the response of St. aureus ATCC 6538 to the presence of crude bacteriocins was realized. It has been observed by the agar spot test that fifteen candidates were active toward Gram-positive targets strains. The secondary screening demonstrated an antagonistic activity oriented only against St. aureus ATCC 6538, leading to the selection of five isolates: Lm14, Lm21, Lm23, Lm24, and Lm25 with a larger inhibition zone compared to the others. The ANOVA statistical analysis reveals a small variation of repeatability: Lm21: 0.56%, Lm23: 0%, Lm25: 1.67%, Lm14: 1.88%, Lm24: 2.14%. Conversely, slight variation was reported in terms of inhibition diameters: 9.58± 0.40, 9.83± 0.46 and 10.16± 0.24 8.5 ± 0.40 10 mm for, Lm21, Lm23, Lm25, Lm14and Lm24, indicating that the observed potential showed a heterogeneous distribution (BMS = 0.383, WMS = 0.117). The repeatability coefficient calculated displayed 7.35%. As for the bacteriocins semiquantification, the five samples exhibited production amounts about 4.16 for Lm21, Lm23, Lm25 and 2.08 AU/ml for Lm14, Lm24. Concerning the sensitivity the crude bacteriocins were fully insensitive to heat inactivation, until 121°C, they preserved the same inhibition diameter. As to, kinetic of growth , the µmax showed reductions in pathogens load for Lm21, Lm23, Lm25, Lm14, Lm24 of about 42.92%, 84.12%, 88.55%, 54.95%, 29.97% in the second trails. Inversely, this pathogen growth after five hours displayed differences of 79.45%, 12.64%, 11.82%, 87.88%, 85.66% in the second trails, compared to the control. This study showed potential inhibition to the growth of this food pathogen, suggesting the possibility to improve the hygienic food quality.
Abstract: Fever, bloody diarrhea and high mortality rate were the main clinical finding in a group of fattening calves. Analysis of corn silage revealed presence of aflatoxins at level of 370 ppb. This level of aflatoxins in the feed of cattle is somewhat low to be the main cause of reported signs. Leukocytopenia, anemia, decreased lymphocytic activity and lowered phagocytic index are the main hematological and immunological alterations in diseased calves. Bacteriological investigation revealed isolation of pathogenic Salmonella typhimurium from the rectal swabs of diseased calves. Our results suggested that, long duration of exposure to aflatoxins even at small concentrations may considered as predisposing factor for the incidence of natural infectious outbreaks as salmonellosis due to its immunosuppressive effect. We can conclude that the veterinarians and owners must be given an attention to the relation between aflatoxicosis and salmonellosis under field condition. We are recommended that the treatment program during similar outbreaks must be including anti-aflatoxins preparations beside the antimicrobial therapy.
Abstract: Antimicrobial activities of aminoreductone (AR), a product formed in the initial stage of Maillard reaction, were screened against pathogenic bacteria. A significant growth inhibition of AR against all 7 isolates (Staphylococcus aureus ATCC® 25923™, Salmonella typhimurium ATCC® 14028™, Bacillus cereus ATCC® 13061™, Bacillus subtilis ATCC® 11774™, Escherichia coli ATCC® 25922™, Enterococcus faecalis ATCC® 29212™, Listeria innocua ATCC® 33090™) were observed by the standard disc diffusion methods. The inhibition zone for each isolate by AR (2.5 mg) ranged from 15±0mm to 28.3±0.4mm in diameter. The minimum inhibitory concentration (MIC) of AR ranging from 20mM to 26mM was proven in the 7 isolates tested. AR also showed the similar effect of growth inhibition in comparison with antibiotics frequently used for the treatment of infections bacteria, such as amikacin, ciprofloxacin, meropennem and levofloxacin. The results indicated that foods containing AR are valuable sources of bioactive compounds towards pathogenic bacteria.