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.

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

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.

Este trabalho utiliza a Análise de Fluxos Metabólicos para estudar o aumento da eficiência da linhagem Burkholderia sacchari (LFM101) na produção de PHB. Foram avaliadas as eficiências de conversão de açúcares em PHA de LFM101. Esta também foi cultivada em batelada alimentada em reator, apresentando o máximo teórico durante um estado pseudo-estacionário sob oferta de glicose. Estes dados, submetidos ao software Metatool, resultaram em mapa metabólico contendo os fluxos das reações centrais ede PHA ocorrido no experimento. Através do cultivo de LFM101 e C. necator sob oferta de glicose marcada com 13C, determinou-se que estas utilizam as mesmas vias para produção de PHA, não justificando a baixa eficiência de LFM101. Em um projeto paralelo, estudou-se a eficiência da produção de PHB utilizando melaço de cana, glicerol cru e acetato, em produtores de hidrogênio e PHA, onde verificou-se não apenas o aumento de PHA em mutantes nifh- de R. capsulatus mas a interação dos parâmetros luz e nitrogênio a partir das metodologias DOE e RSM. / This work applies Metabolic Flux Analysis to discuss the eficiency of Burkholderia sacchari (LFM101) in PHA production from sugars . Conversion yields of LFM101 and Cupriavidus necator from carbohydrates to PHA were assessed. LFM101 was also grown in reactor fed-batch cultivations, and presented the theoretical maximum in a pseudo-steady stage while grown on glucose. These data were submitted to Metatool and resulted in a metabolic network containing the experimental fluxes of central and PHA metabolism. Cultivation of LFM101 and C. necator under 13C- labeled glucose showed that both species use the same metabolic pathways for the biodegradable polymer synthesis. On a parallel project, the efficiency of biopolymer production from molasses, raw glycerol and acetate in strains producing hydrogen and PHA was tested. Results showed that there was not only an increase in PHA production by R. capsulatus nifH- mutants but also the interaction of light and nitrogen effects were studied by DOE and RSM.

Der generalisierte Einsatz von Antibiotika im medizinischen Sektor erzeugt einen hohen Selektionsdruck auf Bakterien. Daher weisen bakterielle Resistenzen gegenüber antimikrobiellen Wirkstoffen eine zunehmende Inzidenz auf. Gegen Antibiotika multiresistente Erreger (MRE), insbesondere Multiresistente Gram-Negative Erreger (MRGN), stellen in Krankenhäusern, aber auch in Tierkliniken ein ernstzunehmendes Problem dar. Das Therapieversagen bei der Behandlung von Infektionen mit 3MRGN oder 4MRGN gefährdet die Gesundheitsversorgung. Die Bedeutung effektiver Kontrollmaßnahmen in der Unterbrechung nosokomialer Infektionsketten rückt in den Fokus. Infektionsprophylaxe wird durch eine Umweltdekontamination in Form von Reinigung und Desinfektion durchgeführt. Zertifizierte Biozide werden routinemäßig eingesetzt. Jedoch weisen einigen Studien auf eine Toleranz von Bakterien gegenüber Desinfektionsmitteln hin. Spezifische Dekontaminationsmaßnahmen könnten daher für die Bekämpfung von MRGN notwendig sein. Ziel der Untersuchung war es zu evaluieren, ob klinische 3MRGN und 4MRGN im Vergleich zu nicht resistenten Referenzstämmen unempfindlicher gegenüber Desinfektionsmitteln reagieren und Desinfektionsprotokolle gegebenenfalls angepasst werden müssen. Dazu wurden sechzehn klinische Stämme der Gattungen Acinetobacter, Pseudomonas und Klebsiella wurden mit fünf korrespondierenden Referenzstämmen in vitro auf deren Empfindlichkeit gegenüber den gängigen Desinfektionsmitteln Natriumhypochlorit, Ethanol, Peressigsäure und Benzalkoniumchlorid untersucht. Die Effizienz wurde anhand von vier aufeinander aufbauenden Testverfahren gemäß den Richtlinien des Verbunds für angewandte Hygiene (VAH, 2015) beurteilt. Diese beinhalten die Bestimmung der minimalen Hemmkonzentration (MHK) und die Durchführung von Suspensionstests und Keimträgerversuchen. Es wurden wirksame Konzentrations-Zeit-Relationen für jeden Teststamm und jede aktive Substanz determiniert. Die Ergebnisse der Suspensionstests über- beziehungsweise unterschreiten die Werte der MHK-Bestimmung um ein Vielfaches. P. aeruginosa tolerierte die höchsten Benzalkoniumchlorid-Konzentrationen, während Acinetobacter-Stämme am empfindlichsten reagierten. Im Vergleich zu Suspensionstests wurden in den praxisnahen Keimträgerversuchen signifikant höhere Konzentrationen an Peressigsäure und Benzalkoniumchlorid ermittelt. Die geringere Empfindlichkeit von P. aeruginosa gegenüber Benzalkoniumchlorid wurde bestätigt. Signifikante Unterschiede zwischen klinischen 3MRGN, 4MRGN und den jeweiligen Referenzstämmen in ihrer Sensitivität gegenüber Bioziden wurden - unabhängig von der angewandten Testmethodik - nicht festgestellt. Im Vergleich der Bakterienspezies wiesen Pseudomonaden eine geringere Sensibilität gegenüber Benzalkoniumchlorid auf, jedoch lagen die bakteriziden Konzentrationen in jedem Fall unterhalb der gelisteten Anwendungskonzentrationen. Der Einfluss organischer Belastung auf die Wirksamkeit von Natriumhypochlorit war signifikant. Die Expositionsdauer führte zu keiner signifikanten Absenkung der Wirkkonzentrationen. Die Annahme, dass antibiotikaresistente Bakterien zwangsläufig biozidresistent sind, konnte anhand unserer Ergebnisse nicht bestätigt werden. Spezielle Desinfektionsprotokolle sind nicht notwendig, solange eine konsequente Einhaltung der durch den Hersteller vorgeschriebenen Konzentrations-Zeit-Relationen gegeben ist. Die Höhe der Desinfektionsmittelkonzentration ist für den Desinfektionserfolg ausschlaggebend, während der Einfluss der Einwirkzeit vernachlässigbar ist. Die MHK-Bestimmung eignet sich im Gegensatz zu praxisnahen Keimträgerversuchen nicht zur Ableitung von Anwendungs-konzentrationen von Desinfektionsmitteln.:1 Einleitung 2 Literatur 2.1 Desinfektion 2.1.1 Allgemeines 2.2 Wirksamkeitsprüfung chemischer Desinfektionsmittel 2.2.1 Allgemeines 2.2.2 VAH-Richtlinie 2.2.3 Minimale Hemmkonzentration 2.2.4 Qualitativer Suspensionstest 2.2.5 Quantitativer Suspensionstest 2.2.6 Quantitativer Keimträgertest 2.3 Bakterielle Resistenzen gegenüber Antibiotika 2.3.1 Allgemeines 2.3.2 Nosokomiale Infektionen 2.3.3 Acinetobacter spp. 2.3.4 Klebsiella spp. 2.3.5 Pseudomonas aeruginosa 2.4 Bakterielle Resistenzen gegenüber Bioziden 2.4.1 Allgemeines 3 Veröffentlichungen 3.1 Veröffentlichung 1 3.2 Veröffentlichung 2 4 Diskussion 5 Zusammenfassung 6 Summary 7 Referenzen 7.1 Literaturverzeichnis 7.2 Tabellenverzeichnis 8 Danksagung

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.

Thirteen bacterial cultures were isolated from the North arm of Great Salt Lake during the months of January and February of 1973. Eleven isolates were gram-negative pleomorphic rods which lysed in hypotonic solution. The remaining two were gram-positive cocci. All isolates and one known strain of Halobacterium salinarium were subjected to examination of morphological, cultural, physiological, and biochemical characteristics. A numerical taxonomic analysis was applied to the compiled characters to compute a coefficient of similarity for each individual isolate as compared to all other isolates. A comparative analysis was included in the similarity computation using characters assembled from those reported in the literature for six taxonomically accepted species of halophilic bacteria. The lake isolates proved to be extreme halophiles with relative high levels of similarity between each other and the known bacteria included in the numerical analysis.

No description available.

No description available.

Several Gram-negative bacteria modify their outer most surface structure, lipopolysaccharide (LPS), to evade immune surveillance and survive within the host. Many of these changes occur within the lipid A domain, a region that is recognized by the innate immune system via Toll-like receptor-4 (TLR4). One such pathogen, Porphyromonas gingivalis, orchestrates chronic inflammatory disease by disrupting immune homeostasis. P. gingivalis initially synthesizes a penta-acylated lipid A that functions as a weak TLR4 agonist but displays tetra-acylated forms that are either immunologically silent or TLR4 antagonists. The impact of lipid A modifications on downstream signaling and antigen-specific immunity are unclear. TLR4 signals from the plasma membrane through a MyD88-dependent pathway and intracellularly through a TRIF-dependent pathway. Here we show that expression of immunological silent or antagonistic lipid A enables P. gingivalis to evade TRIF-dependent signaling in dendritic cells (DCs). Evasion of TRIF signaling accelerated antigen degradation and impaired priming of pathogen-specific T cells. In contrast, a P. gingivalis strain expressing agonist lipid A potently activated TRIF signaling and delayed antigen degradation, thereby preserving peptides for optimal T cell activation. We propose that lipid A modifications control the endocytic activity of DCs and the efficiency at which microbe-specific T cells are primed. We next investigated the impact of purified P. gingivalis LPS on innate signaling and antigen presentation. All P. gingivalis LPS species induced a program of DC maturation that allowed for constitutive antigen uptake and cross-presentation. This was independent of TLR4 agonist activity and required CD14, a protein that transports TLR4 to endosomes where TRIF signaling can occur. Agonist LPS induced signaling through both MyD88 and TRIF and elicited T cell priming. Antagonistic LPS potently accelerated CD14 endocytosis and induced TRIF-biased signaling leading to comparable degree of cross-priming. Immunologically silent LPS promoted CD14 endocytosis but failed to activate signaling and induced T cell tolerance. Collectively, our results demonstrate that modification of lipid A structure enables Gram-negative bacteria to direct the host immune system towards tolerance or immunity. We propose that these findings can be harnessed for therapeutic modulation of the immune system to treat a variety of immune-mediated diseases. / 2021-06-14T00:00:00Z