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
- 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.
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Assessment of the antibacterial properties of n-Hexane extract of Cocos Nucifera and its interactions with some conventional antibiotics
- Authors: Akinyele, Taiwo Adesola
- Date: 2011
- Subjects: Coconut palm , Microbial sensitivity tests , Gram-negative bacterial infections , Vibrio infections , Antibiotics , Hexane , Extracts
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11245 , http://hdl.handle.net/10353/416 , Coconut palm , Microbial sensitivity tests , Gram-negative bacterial infections , Vibrio infections , Antibiotics , Hexane , Extracts
- Description: Cocos nucifera belong to the family Aracaceae (palm Family). The English name is coconut and it is used extensively as medicinal remedies against infections such as urinary tract infections, gastro intestinal infections, skin and wound infections. The in vitro antibacterial (including anti-listerial and anti-vibrio) properties as well as the evaluation of the combination potentials of the plant extract with six front-line antibiotics were evaluated in this study using standard procedures. The in vitro anti-listerial properties of the crude aqueous and n-Hexane extract of the husk of Cocos nucifera were carried out against 37 Listeria isolates. Twenty-nine of the test organisms were susceptible to the aqueous extract while thirty were susceptible to the n-Hexane extract both at the screening concentration of 25 mg/ml. Minimum Inhibitory Concentration (MIC) values for all the susceptible bacteria ranged between 0.6 - 5.0 mg/ml. For the aqueous extract, average log reduction in viable cell count ranged between 0.32 Log10 and 4.8 Log10 CFU/ml after 8 hours interaction in 1 × MIC and 2 × MIC. For the n-Hexane extract, the log reduction ranged between 2.4 Log10 and 6.2 Log10 CFU/ml after 8 hours interaction in 1 × MIC and 2 × MIC. The time-kill characteristics of the two extracts suggest that at higher concentration (2 × MIC) and longer duration of interaction (8 hr), more bacteria were killed. In vitro anti-vibrio and antibacterial properties experiment revealed that of all the 45 vibrio and 25 bacteria strains that was tested, 37 were susceptible to the aqueous extract and 38 to the n-Hexane extract, while 17 were susceptible to the aqueous extract and 21 to the n-Hexane extract. Minimum Inhibitory Concentration (MIC) values for all the susceptible bacteria ranged between 0.3 - 5.0 mg/ml. viii The time kill studies revealed that for the aqueous extract, average log reduction in viable cell count in time kill assay ranged between 0.12 Log10 and 4.2 Log10 CFU/ml after 8 hr interaction at 1 × MIC and 2 × MIC. For the n-Hexane extract, the log reduction ranged between 0.56 Log10 and 6.4 Log10 CFU/ml after 8 hr interaction in 1 × MIC and 2 × MIC. In the test for the combination interactions, the checkerboard method revealed synergy of 67% and indifferent of 33%, while the time kill assay detected synergy in 72% and indifferent in 28% of the combinations tested. The synergy detected was not specific to any of the antibiotics or the Gram reaction of the bacteria, and no antagonism was detected. We conclude that the aqueous and n-Hexane extract of the husk of C. nucifera contains potential broad spectrum antibiotics resistance modulating compounds that could be relevant in the treatment of infections caused by these pathogens. In addition, the husk which is being discarded as agro waste will opens up a vista of opportunities for utilization for therapeutic purposes
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In vitro activity of bioactive compounds of selected South African medicinal plants on clinical isolates of Helicobacter pylori
- Authors: Okeleye, Benjamin Ifeoluwa
- Date: 2011
- Subjects: Helicobacter pylori , Microbial sensitivity tests , Traditional medicine -- South Africa , Gram-negative bacterial infections
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11255 , http://hdl.handle.net/10353/310 , Helicobacter pylori , Microbial sensitivity tests , Traditional medicine -- South Africa , Gram-negative bacterial infections
- Description: The stem bark of Peltophorum africanum and Bridelia micrantha are used in South Africa traditional medicine for treatment of intestinal parasites, relieve problems and human immunodeficiency virus/ acquired immune deficiency syndrome (HIV/AIDS). The growing problem of antibiotic resistance by Helicobacter pylori the major etiological agent in gastritis, gastric cancer, peptic and gastric ulcer demands the search for novel compounds from plant based sources. This study was aimed to determine the antimicrobial activity of five solvent (ethylacetate, acetone, ethanol, methanol and water) extracts of the stem bark of P. africanum and B. micrantha on clinical strains of H. pylori in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs. H. pylori strains were isolated from patients presenting with gastric related morbidities at the Livingstone Hospital, Port Elizabeth for endoscopy and confirmed following standard microbiology procedures. The plant extracts including clarithromycin were tested against 31 clinical strains of H. pylori by the agar well diffusion method. The most potent extract was evaluated by the microdilution method to determine the Minimum Inhibitory Concentration (MIC50&90), followed by the rate of kill. Preliminary phytochemical analysis was carried out. The one way ANOVA test was used to statistically analyse the results. All the extracts demonstrated anti-H. pylori activity with zone diameters of inhibition that ranged from 0 to 23 mm for the extracts and 0 to 35 mm for clarithromycin. Marked susceptibility (100%) was recorded for the ethyl acetate extract of P. africanum (P. afr. EA) and the acetone extract of B. micrantha (B. mic. A), which were statistically significant (P < 0.05) compared to all other extracts and clarithromycin. For B. micrantha ethyl acetate extract, 93.5 percent susceptibility was observed while for the control iv antibiotic, clarithromycin it was 58.1 percent. The MIC50 ranged from 0.0048 to 0.313 mg/mL for P. afr. EA, and from 0.0048 to 0.156 mg/mL for B. mic. EA; MIC90 ranged from 0.156 mg/mL to 0.625 mg/mL and 0.0048 to 2.5 mg/mL for P. afr. EA and B. mic. EA respectively. There was a significant statistical difference observed in potency of both P. afr. EA and B. mic. A compared to the two antibiotics (P < 0.05). One hundred percent killing by P. afr EA was observed at 0.05 mg/mL (½ x MIC) and 0.2 mg/mL (2 x MIC) in 66 h for strain PE466C and PE252C respectively. For B. mic. EA, 100 percent killing effect of both strains (PE430C and PE369C) was observed at 0.1 mg/mL (2 x MIC) in 66 h. Qualitative phytochemical analysis confirmed the presence of alkaloids, flavonoids, steroids, tannins and saponins in the ethyl acetate extracts of both plants, which could be a potential template of lead molecule for the design of new anti- Helicobacter pylori therapies.
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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.
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Prevalence and risk factors for Helicobacter pylori transmission in the Eastern Cape Province application of immunological molecular and demographic methods
- Authors: Dube, Callote
- Date: 2010
- Subjects: Helicobacter pylori , Bacterial diseases , Gastritis -- Risk factors , Bacterial diseases -- Risk factors , Gram-negative bacteria , Gram-negative bacterial infections , Helicobacter , Helicobacter infections , Helicobacter pylori -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11262 , http://hdl.handle.net/10353/265 , Helicobacter pylori , Bacterial diseases , Gastritis -- Risk factors , Bacterial diseases -- Risk factors , Gram-negative bacteria , Gram-negative bacterial infections , Helicobacter , Helicobacter infections , Helicobacter pylori -- South Africa -- Eastern Cape
- Description: Helicobacter pylori (H. pylori) is a microaerophilic, Gram-negative motile curved rod that inhabits the gastric mucosa of the human stomach. The organism chronically infects billions of people worldwide and is one of the most genetically diverse of bacterial species. Infection with the organism potentially induces chronic gastritis and peptic ulcer disease. In addition, H. pylori plays a role in the etiology of gastric cancer and gastric MALT lymphoma. The risk of infection is increased in those living in the developing world, which has been ascribed to precarious hygiene standards, crowded households, and deficient sanitation common in this part of the world. Thus, the aim of this study was to identify the risk factors in the transmission of H. pylori in our environment, i.e. in Nkonkobe Municipality in the Eastern Cape Province, South Africa. Faecal samples were collected from 356 apparently healthy subjects, consisting of 168 males and 188 females aged from 3 months to 60 years (Mean = 31 years). A standardized questionnaire was applied, it described demographic characteristics including age, sex, household hygiene, socioeconomic status, area of residence, duration of stay in the area, sharing bath water, sharing tooth brush, habit of sucking thumb, medication currently being taken or medication taken within the past three months, source of water, type of toilet used, education and occupation. A sandwich-type enzyme immunoassay amplification technology (Amplified IDEIA TM Hp StAR TM , Oxoid, UK) was used to analyze the faecal samples for the detection of H. pylori antigens using monoclonal antibodies specific for H. pylori antigens. To assess the possibility of faecal oral route with tap water as an intermediary link, PCR targeting the ureC (glmM), a highly conserved gene in H. pylori ii was carried out to detect H. pylori DNA in faecal samples of already positive samples by HpSA test as well as in direct tap water used by the H. pylori positive subjects. QIAamp DNA stool mini kit was used to extract DNA from faecal samples. Tap water samples were then obtained using sterile bottles from areas inhabited by H. pylori positive subjects as determined by HpSA test and PCR. DNA extraction from water samples was done using UltraCleanTM Water DNA Isolation Kit (0.22μm) according to the manufacturer’s instructions. PCR with primers specific for H. pylori glmM gene was carried out with both positive and negative controls incorporated. Fisher’s exact test was used to assess the univariate association between H. pylori infection and the possible risk factors. Odds ratio (OR) and the corresponding 95 percent confidence interval (CI) were calculated to measure the strength of association using EPI INFO 3.41 package. P values of < .05 were required for significance. The precision rate of the diagnostic tests used was also determined. H. pylori antigen was detected in 316 of the 356 subjects giving an overall prevalence of 88.8 percent. Prevalence increased with age from 75.9 percent in children < 12 years age to 100 percent in the age group from 13 years to 24 years, also 100 percent prevalence of H. pylori was recorded in young adults aged 25-47 years and subjects aged 60 years (P < .05). H. pylori prevalence was higher in females than in males. Of 188 females who participated in the study, H. pylori antigen was detected in 172 (91.5 percent) versus 144 (85.7 percent) of 168 males (P > .05). Interestingly, H pylori antigen was detected more often (100 percent) in the high socioeconomic group than in those of low socioeconomic group (85.9 percent). Sixteen (66.7 percent) of twenty four faecal samples that had previously tested positive for the organism by HpSA test were confirmed positive by PCR. However none of the treated tap water samples tested positive for the organism by PCR. The present iii study revealed a high prevalence of H. pylori in faecal samples of asymptomatic individuals in the Nkonkobe Municipality, an indication of active infection. The obtained results also revealed that direct treated tap water might not be playing a crucial role in the oral transmission of H. pylori in the studied population.
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