The emergence and spread of multi-drug resistant (MDR-TB) and extensively drugresistant tuberculosis (XDR-TB) are a major medical and public problem threatening the global health. The objectives of this study were to (i) determine the prevalence of MDR-TB and XDR-TB in the Eastern Cape; (ii) analyze patterns of gene mutations in MDR-TB and (iii) identify gene mutations associated with resistance to second line injectable drugs in XDR-TB isolates. A total of 1520 routine sputum specimens sequentially received within a period of 12 months i.e. February 2012 to February 2013 from all MDR-TB and XDR-TB patients treated by Hospitals and clinics in the Eastern Cape were included in this study, of which 1004 had interpretable results. Samples were analyzed with the Genotype MTBDRplus VER 2.0 assay kit (Hain Lifescience) for detection of resistance to Rifampicin and Isoniazid while solid and liquid culture drug susceptibility tests were used for ethambutol, streptomycin, ethionamide, ofloxacin, capreomycin and amikacin. PCR and sequence analysis of short regions of target genes gyrA, (encode subunit of DNA topoisomerase gyrase), rrs (16S rRNA) and tlyA (encodes a 2’-O-methyltransferase) were performed on 20 XDR-TB isolates. MTBDRplus kit results and drug susceptibility tests identified 462 MDR-TB, 284 pre-XDR and 258 XDR-TB isolates from 267 clinics and 25 hospitals in the Eastern Cape. There was a high frequency of resistance to streptomycin, ethionamide, amikacin, ofloxacin and capreomycin. Mutation patterns indicated differences between the health districts as well as differences between the facilities within the health districts. The most common mutation patterns observed were: (i) ΔWT3, ΔWT4, MUT1 [D516V+del515] (rpoB), ΔWT, MUT1 [S315T1] (katG), ΔWT1 [C15T] (inhA) [39 MDR, 204 XDR-TB and 214 pre XDR-TB isolates], (ii) ΔWT8, MUT3 [L533P+S531L] (rpoB), ΔWT, MUT1 [S315T1] [145 MDR, 18 pre-XDR and 3 XDR-TB solates] and (iii) ΔWT3, WT4 [D516Y+del515] (rpoB), ΔWT, MUT1 [S315T1] (katG) [75 MDR, 1 pre-XDR and 7 XDR-TB isolates]. Mutations in inhA promoter regions were strongly associated with XDR-TB isolates. Two thirds (66.6 percent (669/1004) of the isolates had inhA mutations present with 25.4 percent (170/669) found among the MDR isolates, 39.2 percent (262/669) among the pre-XDR isolates and 35.4 percent (237/669) among the XDR-TB isolates, which implies that these resistant isolates are being spread by transmission within the community and circulating in the province. There was good correlation between XDR-TB drug susceptibility test results and sequence analyses of the gyrA and rrs genes. The majority of XDR-TB isolates contained mutations at positions C269T (6/20) and 1401G (18/20) in gyrA and rrs genes respectively. Sequence analysis of short regions of gyrA and rrs genes may be useful for detection of fluoroquinolone and amikacin/ kanamycin resistance in XDR-TB isolates but the tlyA gene is not a sensitive genetic marker for capreomycin resistance. This study highlighted the urgent need for the development of rapid diagnostics for XDR-TB and raised serious concerns regarding ineffective patientmanagement resulting in ongoing transmission of extremely resistant strains of XDRTB in the Eastern Cape suggesting that the Eastern Cape could be fast becoming the epicenter for the development of Totally Drug-resistant Tuberculosis (TDR-TB) in South Africa.

The aim of this study was to assess community members’ knowledge levels regarding Drug Resistant TB and HIV and AIDS. The study was conducted at ward 40 in Green bushes area in Nelson Mandela Metropolitan Municipality (NMMM). A quantitative research method was used in this study. Random sampling is the type of probability sampling method that was used in this study. The sample consisted of 100 respondents above 18 years who were randomly selected from the beneficiary list of for the RDP houses in Green bushes area in the Nelson Mandela Metropolitan Municipality. Data for this study were collected using close ended questions which were administered by the researcher to the selected participants. Data was analysed using bivariate and descriptive statistics according to the identified themes. The study revealed that community members had high knowledge levels regarding Drug Resistant TB and HIV and AIDS prevention, transmission modes and diagnosis and treatment methods. The findings revealed that community members were highly knowledgeable and aware of the fact that abstaining and practising safe sex were means of preventing the spread of HIV and AIDS as it was spread through unprotected sex, while opening of windows and minimisation of close contact with HIV positive people and children with people infected with Drug Resistant TB are infection control measures or methods of preventing the spread of the disease. Additionally, the study indicated that female respondents were more aware and knowledgeable about prevention, transmission modes and diagnosis and treatment of Drug Resistant TB and HIV and AIDS than male respondents. Furthermore, the findings revealed that the respondents were highly knowledgeable and aware about transmission of Drug Resistant TB and HIV and AIDS; knowledgeable about prevention and less knowledgeable about diagnosis and treatment. A high percentage of female respondents knew that there was no vaccine to neither prevent nor cure HIV and AIDS and that antiretroviral drug were used to manage it. The study also showed that female respondents knew that all people irrespective of race and economic class can be infected with Drug Resistant TB and HIV and AIDS. It is important to note that the respondents between 41-60 years possessed more knowledge regarding Drug Resistant TB and HIV and AIDS than the respondents who were between 18-40 years. Lastly, the study showed that there were significant differences in gender and knowledge and no significant differences in age and knowledge of the respondents regarding Drug Resistant TB and HIV and AIDS. It is recommended that in future, research regarding knowledge levels about Drug Resistant TB and HIV and AIDS be extended to other wards in the Nelson Mandela Metropolitan Municipality (NMMM). Accurate knowledge should be provided by ensuring that educational materials that are developed, are appropriate for the various levels of literacy, and that more appropriate and relevant information regarding these diseases is made more accessible to community members in their home languages. The researcher further recommends that during training interventions and educational campaigns more emphasis should be put on prevention, diagnosis and treatment of Drug Resistant TB and HIV and AIDS.

Thesis (MSc. (Medical Sciences)) -- University of Limpopo, 2015 / Introduction: Multidrug-resistant tuberculosis (MDR-TB) caused by resistance to at least rifampicin (RIF) and isoniazid (INH) drugs is a growing public health concern in South Africa. The detection of MDR-TB still relies on culture despite advancement in molecular diagnostic technology. Currently MTBDRplus and GeneXpert are the only available assays used in rapid diagnosis of MDR-TB using chromosomal mutations in drug target regions. Some strains are missed by these assays due to their limitation in mutational detection profile. Novel Seegene Anyplex assays simultaneously detect TB and resistance to RIF and INH using fifteen and six mutational probes, respectively within 3 hours. Limpopo Province has limited information on the circulating strains of TB. Aim: To determine drug-resistant Mycobacterium tuberculosis (M. tuberculosis) mutations using Anyplex™ MTB/NTM/MDR-TB real time assay and characterise the drug-resistant strains. Methods: We prospectively collected 204 clinical samples at Modimolle MDR-TB unit and retrospectively used 104 culture isolates from MRC laboratory in Pretoria. The MTBDRplus assay was used to screen for M. tuberculosis and drug resistant mutations to RIF and INH drugs. Anyplex™ MTB/NTM/MDR-TB assay was used for rapid detection of M. tuberculosis and drug resistance to RIF and INH within 3 hours. The discordance between phenotypic and genotypic assays was resolved by sequencing and the Anyplex™ resistant profiles were spoligotyped. Diagnostic data was collected from NHLS and MRC databases and analysed using the Microsoft excel and Epi Info version 3.5. Descriptive statistics (percentages and frequencies) were used to explain proportions. Results: The Anyplex™ MTB/NTM assay detected M. tuberculosis in 69/111(62%) and 100/104 (96%) of clinical and culture samples respectively. The sensitivities, specificity, PPV and NPV obtained for both RIF and INH resistance by Anyplex™ MDR-TB assay were 67%, 59%, 67%, 55% and 15%, 100%, 100% and 17%, respectively. Anyplex™ MTB/NTM/MDR-TB resolved 23/45 (51%) of discordant vi samples. Sequencing of remaining discordant isolates revealed L511P, L533P and D516Y mutations within rpoB gene. A novel R385W mutation within katG was also detected. Spoligotyping of Anyplex™ MDR-TB resistant clinical isolates revealed Euro American clade with 20% followed by 15% Manu2, 5% East African Indian, 5% H37Rv, 5% atypical and 50% were orphans. Conclusion: The novel Anyplex™ MTB/NTM/MDR-TB assay is a rapid and valid technique for detecting M. tuberculosis and most common mutations conferring resistance to RIF and INH. However further investigations are required, as the assay has a lower sensitivity as compared to already endorsed techniques. / National Research Foundation (NRF) and University of Limpopo TB Grant

The intra- and extracellular activities of 2 novel tetramethylpiperidine (TMP)-substituted phenazines, B4121 and B4128 against Mycobacterium tuberculosis H37R (ATCC 27294) were determined and compared with those of clofazimine (B663). Clofazimine, together with B4121 and B4128, were also tested for their activities against drug-resistant strains of M.tuberculosis. Both B4121 and B4128 were significantly more active than clofazimine against M.tuberculosis, including multidrug-resistant clinical strains of this microbial pathogen, demonstrating a lack of cross resistance between the riminophenazines and standard anti-tuberculous drugs. Using M.tuberculosis-infected monocyte-derived macrophages both B4121 and B4128 were found to possess intracellular activity, which was superior to that of both clofazimine and rifampicin. The relationship between anti mycobacterial action of the TMP-subsitituted phenazines and clofazimine and the effects of these agents on microbial PLA2 activity, cation (K+, Ca2+) fluxes and energy metabolism (ATP) was also investigated. PLA2 and cation fluxes were measured by radiometric procedures, while microbial ATP was assayed using a luciferin/luciferase chemiluminescence method. All 3 riminophenazines, particularly B4128 caused dose-related enhancement of microbial PLA2 activity, which was associated with inhibition of K+-influx and enhancement of uptake of Ca2+. The results of kinetics studies demonstrated that riminophenazine-mediated enhancement of PLA2 activity and inhibition of K+ uptake in mycobacteria are rapidly-occurring and probably related events that precede, by several minutes, any detectable effects on microbial ATP concentrations and uptake of Ca2+. Inclusion of the extracellular and intracellular Ca2+-chelating agents EGTA and BAPTA, respectively, individually or in combination, did not prevent the effects of the riminophenazines on mycobacterial PLA2 (enhancement) or K+ transport (inhibition), whereas α-tocopherol, which neutralizes PLA2 primary hydrolysis products, antagonized the inhibitory effects of the riminophenazines on microbial K+ uptake. These results demonstrated that the riminophenazine-mediated enhancement of PLA2 is a Ca2+-independent event. The involvement of PLA2 in the antimicrobial activity of the riminophenazines was supported by the observation that added, exogenous Iysophosphotidylcholine (a primary hydrolysis product of PLA2 action on membrane phospholipids) also inhibited K+ transport and growth of mycobacteria. Enhancement of endogenous PLA2 as a mechanism of riminophenazine-mediated disruption of cation transport and antimycobacterial activity was further investigated using the conventional calcium-mobilizing stimuli, calcium ionophore A23187 and thapsigargin. Both agents, but A23187 in particular caused in dose-related enhancement of microbial PLA2 activity, which was associated with inhibition of K+ influx and growth. Influx of Ca2+ into A23187- and thapsigargin-treated mycobacteria was observed using both radiometric and FURA-2-based spectrofluorimetric procedures. Exposure of the mycobacteria to these agents resulted in an immediate increase in uptake of Ca2+, which implies that enhancement of PLA2 activity in calcium-mobilizing stimuli-treated mycobacteria is Ca2+ dependent. In conclusion, the TMP-substituted phenazines possess anti mycobacterial properties which are superior to those of clofazimine, particularly against intraphagocytic M.tuberculosis. The superior anti mycobacterial properties of these agents is paralleled by their potentiating effects on microbial PLA2 and consequent inhibitory action on uptake of K+, particularly in the case of B4128. Mycobacterial PLA2 and K+ transporters may therefore represent novel targets for antimicrobial chemotherapy. / Thesis (DPhil (Medical Immunology))--University of Pretoria, 2007. / Immunology / unrestricted

Overuse of conventional antibiotics has led to increased multidrug resistant micro-organisms. Therefore, development of alternative drugs with new mechanisms of action in the control of resistant micro-organisms is urgently needed. Defensins, one of the larger groups of naturally occurring antimicrobial peptides (AMPs), found in a variety of species, may serve as templates for the development of novel therapeutic agents. The work completed in this study is based on an antimicrobial peptide (AMP), Os, derived from the C-terminus of a tick Ornithodoros savignyi defensin isoform 2 (OsDef2). OsDef2 was found to be active against Gram-positive bacteria only, whereas Os, showed bactericidal activity towards both Gram-positive and Gram-negative bacteria. In this study a series of synthetic shorter peptides, based on the sequence of Os, was utilised in order to determine whether shorter peptides would retain their antibacterial activity and selectivity. Initial screening indicated that only two fragments, Os(3-12) and Os(11-22), were active towards the tested Gram-negative and Gram-positive bacteria. The minimum bactericidal concentrations (MBCs) of the two fragments were determined and ranged from 30 μg/ml to 120 μg/ml. The MBCs of the parent peptide, Os (1.88 to 15 μg/ml), was considerably lower than that of Os(3-12) and Os(11-22). As previously observed for Os, neither of the peptides showed cytotoxic effects towards eukaryotic cells. The amidated analogue of one of the active peptides, Os(11-22)NH2, was further evaluated in terms of its secondary structure, antibacterial and antioxidant activities as well as cytotoxicity. Amidation increased the activity of Os(11-22) 16 fold towards B. subtilis (MBC of 1.88 μg/ml) and 32 fold towards both Escherichia coli and Pseudomonas aeruginosa (MBC of 3.75 μg/ml), whereas a 2 fold decrease in activity was observed against Staphylococcus aureus (MBC of 60 μg/ml). Circular dichroism data showed that amidation altered the secondary structure of Os(11-22) from α-helical to mostly random coiled. In the presence of 30% serum the activity of Os(11-22)NH2 unexpectedly increased 8 fold against S. aureus (MBC of 7.5 μg/ml), but decreased 32 fold against E. coli (MBC of 120 μg/ml). The activity of Os(11-22)NH2 in 100 mM NaCl decreased 4 fold against E. coli (MBC of 15 μg/ml), but was completely lost (MBC >120 μg/ml) against S. aureus. The kinetics of bactericidal activity indicated that Os(11-22)NH2 killed B. subtilis and E. coli within 30 min and 120 min, respectively, whereas Os killed both bacteria within 5 min. Even at high concentrations Os(Os(11-22)NH2 was non-toxic towards human erythrocytes and SC-1 cells, moreover an increase in SC-1 cell number was observed at 120 μg/ml. The peptide showed strong antioxidant activity and was found to be 4 fold more active than glutathione (GSH), however Os was 3.4 fold more antioxidative than Os(11-22)NH2. Os(11-22)NH2 can be considered a dual functional peptide, since it possesses both antibacterial and antioxidant activity. The amidated peptide has the potential for use against the damaging effects of oxidative stress associated with infectious diseases and recovery of chronic wounds. Further investigation into structure-function properties of Os(11-22)NH2 is necessary. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Biochemistry / Unrestricted

Cationic steroid antimicrobials (CSAs or ceragenins) are a novel class of synthetic, cholic acid-based mimics of endogenous antimicrobial peptides. These small molecule compounds display broad bactericidal activity against gram-negative and gram-positive bacteria, potent ability against fungal pathogens, and cidal effects against drug resistant and multidrug resistant microbes. Implantable medical devices provide an abiotic surface upon which bacteria and fungi can accumulate--thereby leading to localized or systemic infection. We proposed that CSA antibiotics can be incorporated into medical device surface coatings which can be optimized for the active release or elution of the CSA compounds over time to prevent device-associated infections. This report will discuss the progress of developing and testing coating systems for 3 such devices: cardiac implantable electronic devices (CIED), silicone nasal splints, and breast tissue expanders. In the case of CIEDs, an envelope material containing CSA was created using bioresorbable polymers. We found that this envelope elutes CSA antibiotics and kills all surrounding bacteria or fungi in both planktonic and biofilm forms within 1 hour of exposure. We also developed a nasal splint coating which is directly adhered to the surface of the silicone splint. This coating system demonstrated more than 8 days of protective ability (full microbicidal activity to the detection limit) against Candida albicans, and reduced microbial growth of P. aeruginosa, Candida auris, and MRSA for approximately 6 days. Lastly, in the case of tissue expanders, we developed a layered coating which displays fully-reductive antimicrobial activity against MRSA for 8 days with reintroduction of bacteria every 24 hours. Additionally, this work will discuss our investigations into the secondary properties of ceragenin compounds. On the basis of studies which have demonstrated the pro-osteogenic properties of CSA, we probed the mechanism of this effect. We studied the potential effects of ceragenins on the proliferation, differentiation, and migration of bone-derived mesenchymal stem cells (MSCs). We have determined the absence of any positive proliferative effects of ceragenins on these cells; however, we have demonstrated the significant migration-promoting chemoattractant properties of CSA. In the case of CSA-13, we have observed up to a 400% increase in migration compared to the control. Also, we demonstrated that the P2X7 receptor is strongly implicated in the cellular mechanism of this effect. Our studies of the differentiation-promoting properties of CSA on MSCs have been largely inconclusive, but further investigations are proposed in this report. Lastly, this work includes a report on our investigations into the potential synergistic interactions between CSA-131/CSA-44 with amphotericin B or caspofungin, two commonly used antifungal agents.

Background: Multidrug-resistant Gram-negative bacteria (MDRGN) are found with rising prevalence in non-hemodialysis risk populations as well as hemodialysis (HD) cohorts in Asia, Europe and North America. At the same time, colonization and consecutive infections with such pathogens may increase mortality and morbidity of affected individuals. We aimed to monitor intestinal MDRGN colonization in a yet not investigated German HD population. Methods: We performed cross-sectional point-prevalence testing with 12 months follow-up and selected testing of relatives in an out-patient HD cohort of n = 77 patients by using microbiological cultures from fresh stool samples, combined with Matrix Assisted Laser Desorption Ionization—Time of Flight Mass Spectrometry (MALDI-TOF-MS) and antimicrobial susceptibility testing. Results: We detected MDRGN in 8 out of 77 patients (10.4%) and 1 out of 22 relatives (4.5%), indicating only colonization and no infections. At follow-up, 2 patients showed phenotypic persistence of MDRGN colonization, and in 6 other patients de-novo MDRGN colonization could be demonstrated. Pathogens included Escherichia coli and Klebsiella pneumoniae (with extended-spectrum beta-lactamase [ESBL]-production as well as fluoroquinolone resistance), Stenotrophomonas maltophilia and Enterobacter cloacae. Conclusions: In a single-center study, MDRGN colonization rates were below those found in non-HD high-risk populations and HD units in the US, respectively. Reasons for this could be high hygiene standards and a strict antibiotic stewardship policy with evidence of low consumption of fluoroquinolones and carbapenems in our HD unit and the affiliated hospital.

Thesis (M. Sc. (Chemistry)) -- University of Limpopo, 2021 / Tuberculosis is one of the top 10 leading causes of death in the world. The development of drug resistant strains of Mycobacterium tuberculosis such as Multidrug resistant (MDR) and Extensively drug resistant (XDR) strains further complicate the TB control. Medicinal plants present a possible source for new potential antitubercular drugs. They have played an important role in drug discovery, with many pharmaceutical products originating from them. Isolation and characterisation of new antitubercular compounds from plant extracts is relevant today because of the development of resistant strains. The aim of the study was to evaluate the antimycobacterial activity of the leave extracts of Croton gratissimus and Leonotis leonorus. The first step was to extract fine powder leaves of the two plant species using four (dichloromethane, acetone, hexane and ethanol/water) different solvent systems. Isolation of the fractions was done using column chromatography and preparative thin layer chromatography. Minimum inhibitory concentrations were determined using the broth dilution method and the values were recorded in μg/mL. All the isolated fractions from both plant species were evaluated for preliminary in-vitro antimycobacterial activity. Some of the isolated fractions showed an increased activity against the pathogen as compared to the crude extracts. All the crude extracts of the two plants had activity with MIC90 values greater than 125 μg/mL. Seven fractions obtained from Croton gratissimus showed potential activity against the pathogen with MIC90 values ranging from 30.61 to 64.88 μg/mL. Leonotis leonurus had three fractions with promising activity with MICs ranging from 1.963 to 62.51 μg/mL. The crude extracts of the two plant species showed that the two plant species have antioxidant properties. The qualitative antioxidant assay showed that DCM crude extracts had more antioxidants than all other extracts because of more clear zones against the purple background colour on the TLC plates. These was confirmed by the qualitative antioxidant assay where DCM crude extracts was able to inhibit the highest percentage of DPPH at different concentrations than all other solvent extracts. The DCM crude extracts of L. leonurus and Croton gratissimus inhibited 87 and 93 % of DPPH respectively at 250 μg/mL. The structures of the compounds within the isolated fractions were elucidated using NMR and confirmed by MS and FTIR spectroscopies. The NMR data showed that the isolated fractions were not pure compounds but mixtures of closely related compounds. The compounds whose structures were elucidated included two labdane diterpenoids (Croton A and Croton B) and a Cembranolide ((5E,10E,13R)-4-isopropyl-7,11-dimethyl-15-oxo-14-oxa-bicyclo [11.2.1] hexadeca-5,10-dien-7-yl acetate) from Croton gratissimus and a phenol (4-(3,3,4,4-tetramethylheptyl) benzene-1,2-diol)) from Leonotis leonurus. / National Research Foundation (NRF) and Sasol Foundation

Tuberculosis (TB) is a leading public health problem across the world. For various reasons, TB and multidrug-resistant tuberculosis (MDR-TB) have increased. Clarification on TB/HIV co-infection and homelessness as risk factors for TB and MDR-TB is required to inform policy interventions to reduce TB-related morbidity, mortality, and healthcare costs. In this quantitative study, data from the Houston Health Department (N = 341) were analyzed to explore the relationship between TB and MDR-TB outcomes and TB/HIV co-infection and type of housing/homelessness. Foreign-born persons are disproportionately affected in the United States. The socio-ecological model provided a theoretical framework for the investigation. Multiple and logistic regression analyses were conducted to investigate the relationships between variables, controlling for age and gender. Results indicate that HIV infected persons were more likely than non-infected persons to contract TB, and homeless persons were more likely than non-homeless persons to contract TB/MDR-TB, suggesting that high TB/HIV co-infection rates increase prevalence of TB and MDR-TB while improvements in housing reduce prevalence of TB and MDR-TB. However, no significant associations between variables were found. The odds ratio, Exp(B) = 0.000, p -?¥ 0.90, 95% Cl [0.000, with no upper bound values] was observed for both independent variables. Regular screening for TB/HIV co-infection among persons with high TB and MDR-TB risk profiles is recommended. Further investigation is required. Inclusion of more covariates could further elucidate more evidence of an association between variables. Study findings may support interventions to reduce TB-related morbidity, leading to positive social change.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21258号 / 医博第4376号 / 新制||医||1029(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 松村 由美, 教授 伊達 洋至, 教授 中川 一路 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM