Comparative in-vitro activities of trimethoprimsulfamethoxazole and the new fluoroquinolones against confirmed extended spectrum beta-lactamase producing Stenotrophomonas maltophilia in Nkonkobe Municipality, Eastern Cape environment
- Adeyemi, Oluwatosin Oluwakemi
- Authors: Adeyemi, Oluwatosin Oluwakemi
- Date: 2012
- Subjects: Antibiotics , Microbial sensitivity tests , Drug resistance in microorganisms , Pathogenic microorganisms , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11275 , http://hdl.handle.net/10353/d1007576 , Antibiotics , Microbial sensitivity tests , Drug resistance in microorganisms , Pathogenic microorganisms , Gram-negative bacterial infections
- Description: Stenotrophomonas maltophilia is increasingly emerging as an opportunistic pathogen of global concern. Due to its inherent resistance to several classes of antibiotics including carbapenems and its ability to acquire mobile resistance elements, treatment of infections caused by S. maltophilia is a constant challenge for clinicians. Trimethoprim-sulphamethoxazole (TMP-SMX) is the generally accepted antibiotic of choice for the treatment of infections caused by this organism, but resistance to the drug is increasingly being reported; hence, the need for alternative therapeutic options. In this study, the antimicrobial susceptibility profile of 110 commensal S. maltophilia isolates obtained from Nkonkobe municipality, Eastern Cape Province, Republic of South Africa was investigated. Twenty-one antibiotics including TMP-SMX and the newer fluoroquinolones; levofloxacin, gatifloxacin and moxifloxacin were included in the antibiotic panel. About 63.4 percent of the isolates were susceptible to TMP-SMX with a resistance rate of 28.2 percent. The fluoroquinolones were more effective with susceptibilities ranging from 76 percent to 94.7 percent. Resistance to the fluoroquinolones ranged from 1.3 percent to 2.7 percent. Levofloxacin was the most effective fluoroquinolone tested. Phenotypic dectection of extended spectrum β-lactamases (ESBLs) showed double disc synergy test (DDST) positivity in 59.5 percent of the isolates. Cefepime was the most sensitive indicator cephalosporin in the DDST with 77.3 percent of suspected ESBL-producing isolates showing cefepime-clavulanic acid synergy. Isolates exhibited nine different ESBL phenotypes, however, PCR amplification of the bla genes revealed four isolates that possessed genes belonging to the CTX-M group (CTX-M-1 and CTX-M-8 groups). ESBL genes are usually carried on mobile elements such as plasmids and transposons which may also bear genes that mediate resistance to aminoglycosides, tetracyclines, TMP-SMX and fluoroquinolones. ESBL positive isolates appeared more susceptible to the fluoroquinolones compared to TMP-SMX but there was no significant relationship between ESBL production and susceptibility to these drugs (p > 0.05). The newer fluoroquinolones are a possible alternative treatment option for S. maltophilia infections in this environment but further studies and clinical investigations are needed to determine the in vivo efficacy of these drugs.
- Full Text:
- Date Issued: 2012
- Authors: Adeyemi, Oluwatosin Oluwakemi
- Date: 2012
- Subjects: Antibiotics , Microbial sensitivity tests , Drug resistance in microorganisms , Pathogenic microorganisms , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11275 , http://hdl.handle.net/10353/d1007576 , Antibiotics , Microbial sensitivity tests , Drug resistance in microorganisms , Pathogenic microorganisms , Gram-negative bacterial infections
- Description: Stenotrophomonas maltophilia is increasingly emerging as an opportunistic pathogen of global concern. Due to its inherent resistance to several classes of antibiotics including carbapenems and its ability to acquire mobile resistance elements, treatment of infections caused by S. maltophilia is a constant challenge for clinicians. Trimethoprim-sulphamethoxazole (TMP-SMX) is the generally accepted antibiotic of choice for the treatment of infections caused by this organism, but resistance to the drug is increasingly being reported; hence, the need for alternative therapeutic options. In this study, the antimicrobial susceptibility profile of 110 commensal S. maltophilia isolates obtained from Nkonkobe municipality, Eastern Cape Province, Republic of South Africa was investigated. Twenty-one antibiotics including TMP-SMX and the newer fluoroquinolones; levofloxacin, gatifloxacin and moxifloxacin were included in the antibiotic panel. About 63.4 percent of the isolates were susceptible to TMP-SMX with a resistance rate of 28.2 percent. The fluoroquinolones were more effective with susceptibilities ranging from 76 percent to 94.7 percent. Resistance to the fluoroquinolones ranged from 1.3 percent to 2.7 percent. Levofloxacin was the most effective fluoroquinolone tested. Phenotypic dectection of extended spectrum β-lactamases (ESBLs) showed double disc synergy test (DDST) positivity in 59.5 percent of the isolates. Cefepime was the most sensitive indicator cephalosporin in the DDST with 77.3 percent of suspected ESBL-producing isolates showing cefepime-clavulanic acid synergy. Isolates exhibited nine different ESBL phenotypes, however, PCR amplification of the bla genes revealed four isolates that possessed genes belonging to the CTX-M group (CTX-M-1 and CTX-M-8 groups). ESBL genes are usually carried on mobile elements such as plasmids and transposons which may also bear genes that mediate resistance to aminoglycosides, tetracyclines, TMP-SMX and fluoroquinolones. ESBL positive isolates appeared more susceptible to the fluoroquinolones compared to TMP-SMX but there was no significant relationship between ESBL production and susceptibility to these drugs (p > 0.05). The newer fluoroquinolones are a possible alternative treatment option for S. maltophilia infections in this environment but further studies and clinical investigations are needed to determine the in vivo efficacy of these drugs.
- Full Text:
- Date Issued: 2012
Phytochemical analysis and bioactivity of Garcinia Kola (Heckel) seeds on selected bacterial pathogens
- Seanego, Christinah Tshephisho
- Authors: Seanego, Christinah Tshephisho
- Date: 2012
- Subjects: Drug resistance in microorganisms , Garcinia , Antibiotics , Medicinal plants , Microbial sensitivity tests , Streptococcal infections , Streptococcus , Staphylococcus aureus infections , Salmonella typhimurium , Traditional medicine
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11259 , http://hdl.handle.net/10353/420 , Drug resistance in microorganisms , Garcinia , Antibiotics , Medicinal plants , Microbial sensitivity tests , Streptococcal infections , Streptococcus , Staphylococcus aureus infections , Salmonella typhimurium , Traditional medicine
- Description: Garcinia kola is one of the plants used in folklore remedies for the treatment of microbial infections. Bacterial resistance to commonly used antibiotics has necessitated the search for newer and alternative compounds for the treatment of drug resistant microbial infections. This study focuses on the bioactivity of G. kola seeds on Streptococcus pyogenes (ATCC 49399), Staphylococcus aureus (NCTC 6571), Plesiomonas Shigelloides (ATCC 51903) and Salmonella typhimurium (ATCC 13311), organisms which can cause illnesses from mild to severe with potentially fatal outcomes. The crude ethyl acetate, ethanol, methanol, acetone and aqueous extracts were screened by agar-well diffusion method and the activities of the extract were further determined by Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays. The inhibition zones ranged from 0 - 24 mm, while MIC and MBC of the extract ranged between 0.04 - 1.25 mg/mL and 0.081 - 2.5 mg/mL respectively. Chloroform/ Ethyl Acetate/ Formic acid (CEF) solvent system separated more active compounds followed by Ethyl Acetate/ Methanol/ Water (EMW) and Benzene/ Ethanol/ Ammonium Hydroxide (BEA). The extracts were fractionated by Thin Layer Chromatography (TLC). Bioautography was used to assess the activity of the possible classes of compounds present in the more active extracts. Column chromatography was used to purify the active compounds from the mixture while Gas Chromatography-Mass Spectrometry (GC-MS) was used to identify the phyto components of the fractions. The MIC of the fractions ranged between 0.0006 - 2.5 mg/mL. CEF 3 (F3), CEF 11 (F11) and CEF 12 (F12) revealed the presence of high levels fatty acids Linoleic acid, 1, 2-Benzenedicarboxylic acid and 2, 3-Dihydro-3, 5-dihydroxy-6-methyl, respectively. The results obtained from this study justify the use of this plant in traditional medicine and provide leads which could be further exploited for the development of new and potent antimicrobials.
- Full Text:
- Date Issued: 2012
- Authors: Seanego, Christinah Tshephisho
- Date: 2012
- Subjects: Drug resistance in microorganisms , Garcinia , Antibiotics , Medicinal plants , Microbial sensitivity tests , Streptococcal infections , Streptococcus , Staphylococcus aureus infections , Salmonella typhimurium , Traditional medicine
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11259 , http://hdl.handle.net/10353/420 , Drug resistance in microorganisms , Garcinia , Antibiotics , Medicinal plants , Microbial sensitivity tests , Streptococcal infections , Streptococcus , Staphylococcus aureus infections , Salmonella typhimurium , Traditional medicine
- Description: Garcinia kola is one of the plants used in folklore remedies for the treatment of microbial infections. Bacterial resistance to commonly used antibiotics has necessitated the search for newer and alternative compounds for the treatment of drug resistant microbial infections. This study focuses on the bioactivity of G. kola seeds on Streptococcus pyogenes (ATCC 49399), Staphylococcus aureus (NCTC 6571), Plesiomonas Shigelloides (ATCC 51903) and Salmonella typhimurium (ATCC 13311), organisms which can cause illnesses from mild to severe with potentially fatal outcomes. The crude ethyl acetate, ethanol, methanol, acetone and aqueous extracts were screened by agar-well diffusion method and the activities of the extract were further determined by Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays. The inhibition zones ranged from 0 - 24 mm, while MIC and MBC of the extract ranged between 0.04 - 1.25 mg/mL and 0.081 - 2.5 mg/mL respectively. Chloroform/ Ethyl Acetate/ Formic acid (CEF) solvent system separated more active compounds followed by Ethyl Acetate/ Methanol/ Water (EMW) and Benzene/ Ethanol/ Ammonium Hydroxide (BEA). The extracts were fractionated by Thin Layer Chromatography (TLC). Bioautography was used to assess the activity of the possible classes of compounds present in the more active extracts. Column chromatography was used to purify the active compounds from the mixture while Gas Chromatography-Mass Spectrometry (GC-MS) was used to identify the phyto components of the fractions. The MIC of the fractions ranged between 0.0006 - 2.5 mg/mL. CEF 3 (F3), CEF 11 (F11) and CEF 12 (F12) revealed the presence of high levels fatty acids Linoleic acid, 1, 2-Benzenedicarboxylic acid and 2, 3-Dihydro-3, 5-dihydroxy-6-methyl, respectively. The results obtained from this study justify the use of this plant in traditional medicine and provide leads which could be further exploited for the development of new and potent antimicrobials.
- Full Text:
- Date Issued: 2012
Bioactivity and phytochemical analysis of Hydnora Africana on some selected bacterial pathogens
- Authors: Nethathe, Bono Bianca
- Date: 2011
- Subjects: Helicobacter pylori , Medicinal plants -- South Africa -- Eastern Cape , Microbial sensitivity tests , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Plants -- Analysis , Staphylococcus aureus , Aeromonas hydrophila , Drug resistance in microorganisms , Plant-pathogen relationships
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11247 , http://hdl.handle.net/10353/d1001063 , Helicobacter pylori , Medicinal plants -- South Africa -- Eastern Cape , Microbial sensitivity tests , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Plants -- Analysis , Staphylococcus aureus , Aeromonas hydrophila , Drug resistance in microorganisms , Plant-pathogen relationships
- Description: Abstract Medicinal plants have been for long remedies for human diseases because they contain components of therapeutic value. The growing problem of antibiotic resistance by organisms demands the search for novel compounds from plant based sources. The present study was aimed at evaluating the bioactivity and phytochemical analysis of Hydnora africana on clinical and standard strains of Helicobacter pylori (PE 252C and ATCC 43526), Aeromonas hydrophila ATCC 35654, and Staphylococcus aureus NCT 6571 in an effort to identify potential sources of cheap starting materials for the synthesis of new drugs against these strains. Ethyl acetate, acetone, ethanol, methanol, and water crude extracts of H. africana were screened for activity against the test organisms using the agar well diffusion assay. The Minimum Inhibitory Concentration (MIC50) and Minimum Bactericidal Concentration (MBC) of the most potent extracts were determined by the microdilution method, followed by qualitative phytochemical analysis. Results were analyzed statistically by ANOVA one - way test. Different concentrations (200,100, 50mg/mL) of the methanol, acetone, ethanol and ethyl acetate extracts showed activity against S. aureus and A. hydrophila while for H. pylori, only methanol and ethyl acetate extracts were active; water showed no activity for all studied bacterial pathogens. Mean zone diameter of inhibition which ranged from 0-22mm were observed for all test bacterial pathogens and 14-17mm for ciprofloxacin. The activity of methanol and ethyl acetate extracts were statistically significant (P< 0.05) compared to all the other extracts. MIC50 and MBC ranged from 0.078 – 2.5mg/mL, 0.78-25mg/mL respectively for all tested bacterial pathogens. For ciprofloxacin, the MIC50 and MBC ranged from 0.00976 – 0.078mg/mL and 0.098– 0.78mg/mL respectively. There was no statistically significant difference between extracts (methanol, acetone, ethanol, ethyl acetate) and the control antibiotic (ciprofloxacin) (P> 0.05). Qualitative phytochemical analysis confirmed the presence of alkaloids, saponins, steroids, tannins and flavonoids in the methanol, acetone,ethanol and ethyl acetate extracts. The results demonstrate that H. africana may contain compounds with therapeutic potentials which can be lead molecules for semi-synthesis of new drugs.
- Full Text:
- Date Issued: 2011
- Authors: Nethathe, Bono Bianca
- Date: 2011
- Subjects: Helicobacter pylori , Medicinal plants -- South Africa -- Eastern Cape , Microbial sensitivity tests , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Plants -- Analysis , Staphylococcus aureus , Aeromonas hydrophila , Drug resistance in microorganisms , Plant-pathogen relationships
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11247 , http://hdl.handle.net/10353/d1001063 , Helicobacter pylori , Medicinal plants -- South Africa -- Eastern Cape , Microbial sensitivity tests , Herbs -- Therapeutic use -- South Africa -- Eastern Cape , Plants -- Analysis , Staphylococcus aureus , Aeromonas hydrophila , Drug resistance in microorganisms , Plant-pathogen relationships
- Description: Abstract Medicinal plants have been for long remedies for human diseases because they contain components of therapeutic value. The growing problem of antibiotic resistance by organisms demands the search for novel compounds from plant based sources. The present study was aimed at evaluating the bioactivity and phytochemical analysis of Hydnora africana on clinical and standard strains of Helicobacter pylori (PE 252C and ATCC 43526), Aeromonas hydrophila ATCC 35654, and Staphylococcus aureus NCT 6571 in an effort to identify potential sources of cheap starting materials for the synthesis of new drugs against these strains. Ethyl acetate, acetone, ethanol, methanol, and water crude extracts of H. africana were screened for activity against the test organisms using the agar well diffusion assay. The Minimum Inhibitory Concentration (MIC50) and Minimum Bactericidal Concentration (MBC) of the most potent extracts were determined by the microdilution method, followed by qualitative phytochemical analysis. Results were analyzed statistically by ANOVA one - way test. Different concentrations (200,100, 50mg/mL) of the methanol, acetone, ethanol and ethyl acetate extracts showed activity against S. aureus and A. hydrophila while for H. pylori, only methanol and ethyl acetate extracts were active; water showed no activity for all studied bacterial pathogens. Mean zone diameter of inhibition which ranged from 0-22mm were observed for all test bacterial pathogens and 14-17mm for ciprofloxacin. The activity of methanol and ethyl acetate extracts were statistically significant (P< 0.05) compared to all the other extracts. MIC50 and MBC ranged from 0.078 – 2.5mg/mL, 0.78-25mg/mL respectively for all tested bacterial pathogens. For ciprofloxacin, the MIC50 and MBC ranged from 0.00976 – 0.078mg/mL and 0.098– 0.78mg/mL respectively. There was no statistically significant difference between extracts (methanol, acetone, ethanol, ethyl acetate) and the control antibiotic (ciprofloxacin) (P> 0.05). Qualitative phytochemical analysis confirmed the presence of alkaloids, saponins, steroids, tannins and flavonoids in the methanol, acetone,ethanol and ethyl acetate extracts. The results demonstrate that H. africana may contain compounds with therapeutic potentials which can be lead molecules for semi-synthesis of new drugs.
- Full Text:
- Date Issued: 2011
In-vitro anti-vibrio activities of crude extracts of Garcinia Kola seeds
- Authors: Penduka, Dambudzo
- Date: 2011
- Subjects: Microbial sensitivity tests , Drug resistance in microorganisms , Antibiotics , Garcinia , Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11256 , http://hdl.handle.net/10353/405 , Microbial sensitivity tests , Drug resistance in microorganisms , Antibiotics , Garcinia , Medicinal plants
- Description: The n-Hexane, dichloromethane, methanol and aqueous crude extracts of Garcinia kola (Heckel) seeds were screened for their anti-Vibrio activities against 50 Vibrio bacteria isolated from wastewater final effluents. The 50 isolates consisted of different Vibrio species namely V. fluvialis (14), V. vulnificus (12), V. parahaemolyticus (12), V. metschnikovii (3) and 9 others unidentified to the specie level. The n-Hexane, dichloromethane and methanol extracts had activities against 16 (32 percent) of the Vibrio isolates, while the aqueous extracts had activities against 12 (24 percent) all at a screening concentration of 10 mg/ml. The minimum inhibitory concentrations (MICs) were 0.313-0.625 mg/ml, 0.313-0.625 mg/ml, 0.313-2.5 mg/ml and 10 mg/ml for n-Hexane, dichloromethane, methanol and aqueous extracts respectively. Rate of kill studies were carried out against three different Vibrio species namely V. vulnificus (AL042), V. parahaemolyticus (AL049) and V. fluvialis ( AL040) using the n-Hexane, dichloromethane and methanol extracts at 1× to 4 × MICs and 2 hour exposure. About 96.3 percent, 82.2 percent, and 78.1 percent (V. fluvialis AL040); 92.6 percent, 87.8 percent and 68.9 percent (V. parahaemolyticus AL049); and 91.6 percent, 64.4 percent, 60 percent (V. vulnificus AL042) of the bacteria were killed by the crude n-Hexane, dichloromethane and methanol extracts respectively after 2 hour exposure time at 4× MIC. The patterns of activity were bacteriostatic, with the n-Hexane extracts being most effective in activity. We conclude that the Garcinia kola seeds have promise in the treatment and management of infections caused by Vibrio species.
- Full Text:
- Date Issued: 2011
- Authors: Penduka, Dambudzo
- Date: 2011
- Subjects: Microbial sensitivity tests , Drug resistance in microorganisms , Antibiotics , Garcinia , Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11256 , http://hdl.handle.net/10353/405 , Microbial sensitivity tests , Drug resistance in microorganisms , Antibiotics , Garcinia , Medicinal plants
- Description: The n-Hexane, dichloromethane, methanol and aqueous crude extracts of Garcinia kola (Heckel) seeds were screened for their anti-Vibrio activities against 50 Vibrio bacteria isolated from wastewater final effluents. The 50 isolates consisted of different Vibrio species namely V. fluvialis (14), V. vulnificus (12), V. parahaemolyticus (12), V. metschnikovii (3) and 9 others unidentified to the specie level. The n-Hexane, dichloromethane and methanol extracts had activities against 16 (32 percent) of the Vibrio isolates, while the aqueous extracts had activities against 12 (24 percent) all at a screening concentration of 10 mg/ml. The minimum inhibitory concentrations (MICs) were 0.313-0.625 mg/ml, 0.313-0.625 mg/ml, 0.313-2.5 mg/ml and 10 mg/ml for n-Hexane, dichloromethane, methanol and aqueous extracts respectively. Rate of kill studies were carried out against three different Vibrio species namely V. vulnificus (AL042), V. parahaemolyticus (AL049) and V. fluvialis ( AL040) using the n-Hexane, dichloromethane and methanol extracts at 1× to 4 × MICs and 2 hour exposure. About 96.3 percent, 82.2 percent, and 78.1 percent (V. fluvialis AL040); 92.6 percent, 87.8 percent and 68.9 percent (V. parahaemolyticus AL049); and 91.6 percent, 64.4 percent, 60 percent (V. vulnificus AL042) of the bacteria were killed by the crude n-Hexane, dichloromethane and methanol extracts respectively after 2 hour exposure time at 4× MIC. The patterns of activity were bacteriostatic, with the n-Hexane extracts being most effective in activity. We conclude that the Garcinia kola seeds have promise in the treatment and management of infections caused by Vibrio species.
- Full Text:
- Date Issued: 2011
Phytochemical analysis and bioactivity of the stem bark of Combretum Molle on some selected bacterial pathogens
- Authors: Nyenje, Mirriam, E
- Date: 2011
- Subjects: Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11261 , http://hdl.handle.net/10353/391 , Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Description: Antimicrobial resistance is a worldwide problem that has deleterious long-term effects as the development of drug resistance outpaces the development of new drugs. Plants have been used for many generations for healing purposes, and screening of extracts of these plants has often yielded positive outcomes. This study was aimed at isolating and characterizing the major active antimicrobial compounds present in the stem bark of C. molle, in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. Various solvents (hexane, ethyl acetate, dichloromethane, acetone, ethanol and methanol) were used for extraction. The agar well diffusion technique was used to screen for antimicrobial activity of C. molle extracts against Streptococcus pyogenes ATCC 49399, Plesiomonas shigelloides ATCC 51903, Pseudomonas aeruginosa ATCC 15442, Helicobacter pylori ATCC 43526 and Helicobacter pylori 252C (clinical isolate); minimum inhibition concentration (MIC) of the most active extracts was determined by the broth dilution method. Fractionation of acetone extract was done by thin layer chromatography (TLC) and bioautography to determine the compounds present and their antimicrobial activity respectively. The acetone extract was purified by column chromatography and their MIC determined. The most potent fraction (EA4) was subjected to Gas chromatography- Mass spectrometry (GC-MS) and High performance liquid chromatography (HPLC) for identification of the active compounds. Results were analyzed by the Fisher‟s exact test. All the extracts tested demonstrated antimicrobial activity with zone diameters of inhibition ranging from 0–32 mm. Acetone was the most potent extract with its MIC ranging from 0.078–5.0 mg/mL. Seventeen fractions were collected from column chromatography and the most active fraction against all the organisms was EA 4 (eluted with 100 percent ethyl acetate), with its MIC ranging from 0.078 - 2.5mg/mL. There was no statistically significant difference (P>0.05) in the potency of the xii four extracts (acetone, methanol, ethanol and ethyl acetate) and antibiotic (ciprofloxacin) on the different bacterial strains tested, likewise the crude extract and the fractions. No compound was detected by GC-MS whereas numerous peaks were identified by HPLC implying that the active compounds in this plant are non volatile. We could not identify the compounds thereby proposing further studies using Nuclear magnetic resonance to identify the compounds. The study revealed that the acetone extract of C. molle was the most active against all the test organisms and therefore justifies the use of this plant in traditional medicine.
- Full Text:
- Date Issued: 2011
- Authors: Nyenje, Mirriam, E
- Date: 2011
- Subjects: Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11261 , http://hdl.handle.net/10353/391 , Drug resistance in microorganisms , Materia medica, Vegetable , Antibiotics , Microbial sensitivity tests , Gram-negative bacterial infections
- Description: Antimicrobial resistance is a worldwide problem that has deleterious long-term effects as the development of drug resistance outpaces the development of new drugs. Plants have been used for many generations for healing purposes, and screening of extracts of these plants has often yielded positive outcomes. This study was aimed at isolating and characterizing the major active antimicrobial compounds present in the stem bark of C. molle, in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. Various solvents (hexane, ethyl acetate, dichloromethane, acetone, ethanol and methanol) were used for extraction. The agar well diffusion technique was used to screen for antimicrobial activity of C. molle extracts against Streptococcus pyogenes ATCC 49399, Plesiomonas shigelloides ATCC 51903, Pseudomonas aeruginosa ATCC 15442, Helicobacter pylori ATCC 43526 and Helicobacter pylori 252C (clinical isolate); minimum inhibition concentration (MIC) of the most active extracts was determined by the broth dilution method. Fractionation of acetone extract was done by thin layer chromatography (TLC) and bioautography to determine the compounds present and their antimicrobial activity respectively. The acetone extract was purified by column chromatography and their MIC determined. The most potent fraction (EA4) was subjected to Gas chromatography- Mass spectrometry (GC-MS) and High performance liquid chromatography (HPLC) for identification of the active compounds. Results were analyzed by the Fisher‟s exact test. All the extracts tested demonstrated antimicrobial activity with zone diameters of inhibition ranging from 0–32 mm. Acetone was the most potent extract with its MIC ranging from 0.078–5.0 mg/mL. Seventeen fractions were collected from column chromatography and the most active fraction against all the organisms was EA 4 (eluted with 100 percent ethyl acetate), with its MIC ranging from 0.078 - 2.5mg/mL. There was no statistically significant difference (P>0.05) in the potency of the xii four extracts (acetone, methanol, ethanol and ethyl acetate) and antibiotic (ciprofloxacin) on the different bacterial strains tested, likewise the crude extract and the fractions. No compound was detected by GC-MS whereas numerous peaks were identified by HPLC implying that the active compounds in this plant are non volatile. We could not identify the compounds thereby proposing further studies using Nuclear magnetic resonance to identify the compounds. The study revealed that the acetone extract of C. molle was the most active against all the test organisms and therefore justifies the use of this plant in traditional medicine.
- Full Text:
- Date Issued: 2011
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