- Email: [email protected]
O177 Biofilm formation may be an independent virulence factor in wild-type Staphylococcus saprophyticus strain 7108 in contrast to wild-type strain CCM 883
S36 zAG, and all BALF samples negative for zAg were also negative for zygomycete DNA by PCR. Conclusion: zAg and zygomycete DNA are present in BALF of patients with IZ, and might be a useful tool for early diagnosis. The presence of both markers in BALF samples from high-risk patients without a clinically manifest disease might indicate the presence of colonisation or subclinical infection.
Slime wars: an in-depth look at biofilms O174 Growth, adhesion and biofilm formation of Pseudomonas aeruginosa with antibiotic-induced morphological changes under the influence of dynamic conditions
17th ECCMID / 25th ICC, Oral presentations Results: All the strains tested were able to form biofilm in all the media tested. However, differences were detected between the different media. The isolates were able to form biofilm faster in Middlebrook 7H9 (100% of surface covered in day 28 for all the strains) than in tap water (100% of surface covered in day 63 for all the strains). The day 70 none of strains covered all the surface when using PBS-5% glucose. No difference was found between species in biofilm development. Conclusions: All the NPRGM tested were able to develop biofilm in all tested media. The biofilm development is dependent on the type of the culture media, being faster when a rich media is used. No differences were detected in biofilm development among the different species. Acknowledgments: T.J. Kinnari was funded by a grant from the Academy of Finland. N. Zamora was funded by a grant from the Fundaci´on Conchita R´abago de Jim´enez D´ıaz (Madrid, Spain).
A.P. Fonseca, J.C. Sousa (Porto, PT) Objectives: The aim of this study was to investigate the effect of dynamic conditions and antibiotic-induced morphological changes on growth, adhesion and biofilm formation ability of Pseudomonas aeruginosa. Methods: A modified microtitre plate assay was used to quantify adhesion, biofilm formation and planktonic culture density of Pseudomonas aeruginosa ATCC 27853 under the effect of 0.5 Minimal Inhibitory Concentration (MIC) of Piperacillin/Tazobactam, Imipenem and Meropenem. Hydrodynamic conditions were obtained by orbital shaking at 250 rpm with the presence of a glass bead in each microtitre well. Results: These conditions decreased the adhesion and biofilm formation abilities of bacteria with antibiotic-induced morphological changes in comparison to static conditions. The planktonic culture density significantly correlates with adhesion but not with biofilm formation. Conclusion: Our results demonstrate the importance of using a high-throughput dynamic model to assess the adhesion and biofilm formation deficient behaviour of P. aeruginosa with antibiotic-induced morphological changes and suggest the possible use of sub-MIC antibiotics in clinical applications to prevent infections acquired by haematogenous spread. This dynamic model contributes to a better simulation of in vivo conditions of adhesion and biofilm formation of P. aeruginosa with altered morphologies induced by b-lactam antibiotics. Acknowledgments: This study was supported by a grant from Funda¸ca˜ o Calouste Gulbenkian (Ref. 47273).
O175 Differences in biofilm development by non-pigmented rapidly growing mycobacteria using different culture media J. Esteban, N. Zamora, R. Fernandez Roblas, I. Gadea, H. Adames, T.J. Kinnari (Madrid, ES) Objective: To evaluate the ability of different species of nonpigmented rapidly growing mycobacteria to develop biofilm in different culture media using a microtiter plate assay. Methods: Collection strains (Mycobacterium fortuitum ATCC 6841 and ATCC 13756, M. chelonae ATCC 19235 and ATCC 35752, M. abscessus DSM 44196, M. peregrinum ATCC 14467, M. mucogenicum DSM 44124, M. septicum ATCC 700731, M. immunogenum ATCC 700505, M. mageritense ATCC 700351, M. porcinum ATCC 33776, M. elephantis DSM 44368, M. smegmatis CECT 3032, CECT 3020 and CECT 3017, M. goodii ATCC 700504, M. alvei CECT 3021, and M. brumae CECT 3022) of non-pigmented rapidly growing mycobacteria (NPRGM) were inoculated in tissue culture-treated polystyrene microtiter plates and incubated in Middlebrook 7H9, PBS-5% glucose or sterile tap water. Plates were incubated at room temperature with rotation during 70 days, and media were changed each 4 days. One well for each strain and medium was stained with Fuchsin, decoloured with ethanol, and photographed to measure the biofilm development the days 1, 4, 8, 12, 20, 27, 34, 41, 48, 55, 62 and 70. Calculation of the surface covered by bacteria was performed analysing the photograps with the ImageJ software for Windows.
O176 Effect of Fe and glucose on the glycolysis and gluconeogenesis in biofilm-associated Staphylococcus epidermidis C. Massonet, V. Pintens, R. Merckx, J. Van Eldere (Leuven, BE) Objective: To determine the role of GapA (glycolysis) and GapB (gluconeogenesis) in Staphylococcus epidermidis biofilms. Methods: A biofilm-forming S. epidermidis strain from a proven catheter-related infection was used. For in vitro studies, to examine the influence of glucose, bacteria were grown overnight in BHI and re-incubated in BHI (glucose-rich; Fe-rich) or 0.9% NaCl (glucoselimited; Fe-rich). To examine the influence of iron (Fe) bacteria were grown overnight in RPMI without Fe (fRPMI) and re-incubated in fRPMI (glucose-rich; Fe-limited) or fRPMI with 25 mM Fe (glucoserich; Fe-rich). For in vivo studies a subcutaneous rat model was used. Quantification of bacteria and gene expression through Taqman PCR were performed as described by S. Vandecasteele et al. (Biochem. Biophys. Res. Commun. 2002; 291: 528–534). Extracellular matrix and bacteria were visualised through confocal laser scanning microscopy (CLSM). Results: In vitro, in a glucose-rich environment the expression of gapA and gapB did not differ between planktonic and sessile bacteria and stayed constant over time. Both in planktonic and sessile bacteria, expression of gapA was up-regulated in comparison to gapB. In vitro, in a glucose-limited environment, expression of gapA in sessile bacteria decreased in comparison to its expression in planktonic bacteria and expression of gapB in sessile bacteria increased to the expression level of gapA in sessile bacteria. In vitro, in sessile bacteria, gapB expression was high in a medium with a low Fe content, irrespective of the glucose content. Simultaneously with the increased expression of gapB, PIA production could be visualised through CLSM in sessile bacteria in all media. In vivo expression of gapA was high and remained constant over a period of two weeks. The expression of gapB decreased during the initial phase of implantation, but reached the expression level of gapA after two weeks of implantation. Conclusion: The persistent expression of gapA in sessile bacteria could indicate a role in biofilm formation, especially in the early stages, while expression levels of gapB could indicate a role in the later phases of biofilm formation. Results of gene expression and CLSM indicate a link between gapB and PIA production that is influenced by both Fe and glucose. O177 Biofilm formation may be an independent virulence factor in wild-type Staphylococcus saprophyticus strain 7108 in contrast to wild-type strain CCM 883 F. Szabados, K. Strate, M. Kaase, T. Sakinc, A. Anders, S. Gatermann (Bochum, DE) S. saprophyticus is second only to E. coli the most important causative organism of uncomplicated urinary tract infection in young female outpatients. Compared to S. aureus and S. epidermidis only very few virulence factors in S. saprophyticus have been described, for
Antiretroviral treatment example Ssp, a surface-associated lipase, Aas, an autolysin adhesin, SdrI, a collagen binding protein, and urease activity. Purportedly, the uropathogenicity of S. saprophyticus can be attributed to its ability to cope with the high range of variation in salt- and urea-concentration in human urine. The aim of this study was to elucidate virulence factors of uropathogenicity. Methods: Bacterial growth was examined under different conditions using a modified model of artificial urine as previously described. Bacterial aggregation was observed in bright light and electron micrographs. Biofilm formation was tested using native polystyrene and crystalline pre-coated microtiter plates. Results: In S. saprophyticus strain CCM 883, in contrast to wild-type strain 7108, generation-time was increased. In S. saprophyticus wild-type strains 7108 and 9325, bacterial aggregation appeared near large crystal structures in contrast to its urease negative derivative strain GJ1187 and the wild type strain CCM 883. In native polystyrene and crystalline precoated microtiter plates, biofilm formation was observed in strain 7108 in contrast to strain CCM 883. The biofilm formation in S. saprophyticus seems independent of agr-, Ssp-, SdrI, since no difference between knockout mutants to wild type strain was observed. Conclusion: Bacterial aggregation could be due to increased adhesion. The lipase activity may modulate hydrophobicity and Ca2+ binding. Higher local Ca2+ concentration, as well as strengthened bacterial aggregation, may lead to increased crystal formation. Bacteria may adhere to crystals, additionally to the later mechanism due to biofilm formation. In crystallisation process, bacteria were embedded into the crystal structure. This may be a new model of infectious stone genesis. This study strongly suggest that S. saprophyticus wild-type strain CCM 883 lacks important virulence factors in contrast to wild-type strain 7108 and biofilm formation may play an important role in S. saprophyticus urinary tract infection. O178 Production of an anti-biofilm molecule by Candida albicans yeasts growing as a biofilm
S37 properties of this antigen are that it is highly immunogenic, it is not found in BCG or many environmental mycobacteria, and it is a key virulence factor. Its immunogenicity and specificity led to a series of studies to assess its potential as a major component of new diagnostic tests. Such tests have evolved into two major forms-a whole blood assay marketed under the name Quantiferon and an ELISPOT assay marketed under the name T-spot. New antigens have been assessed for improved test performance, most notably CFP-10. Studies of in-house versions of these assays, and more recently the commercial kits, have shown encouraging results in TB cases for the diagnosis of disease and in their close contacts for the diagnosis of M. tuberculosis infection. It is clear that these tests are not confounded by prior BCG vaccination and are probably not subject to boosting by injected tuberculin. Their quantitative readouts may also provide important information with respect to infectious load. However, some findings have caused concern: disparity in test performance between temperate non-TB endemic and tropical TB-endemic settings, evidence of relatively poor sensitivity to the presence of certain M. tuberculosis strains (eg. M. africanum) and in certain sub-groups (eg. Pulmonary TB, certain TB contacts), and rapid unexplained test reversion. It is therefore becoming clear that T cell assays may have a niche in the diagnosis of certain TB cases and in certain individuals suspected of having M. tuberculosis infection, but this niche has not yet been fully defined. More longitudinal studies, especially following TB case contacts for the development of disease, are indicated. Also more studies should be undertaken in TB endemic areas. Finally, if these tests are to have any role in TB control globally they would need to be much cheaper and more easy to use. Some advances with respect to these two issues have already taken place.
Antiretroviral treatment S184 New targets for innovative HIV treatment G. F¨atkenheuer (Cologne, DE)
E. Cateau, J. Berjeaud, M. Rodier, C. Imbert (Poitiers, FR) Objectives: The influence of biofilm formation in catheter-related candidiasis has been established and it has been shown that the development of biofilm by the colonising yeasts confers resistance to antifungals. The purpose of this work was to demonstrate the production, by the Candida albicans yeasts growing as a biofilm, of a molecule able to reduce biofilm growth. Methods: An in vitro model of C. albicans biofilm associated with 100% silicone catheters was used. The supernatant medium recovered from C. albicans (ATCC 3153) biofilm aged of 24 hours was added during the course of a new biofilm formation made with 4 C. albicans strains (182, 444, 2091 and ATCC 3153), and its influence was subsequently evaluated with XTT method. Ultrafiltration and purification assays to characterise the modulating fungal molecule responsible for the biofilm supernatant activity are presented in this study. Results: The addition of the supernatant to adherent C. albicans cells induced a significant (p < 0.001) inhibition of the biofilm growth. This activity was not observed when the supernatant was added to preformed biofilms. Ultrafiltration and purification assays demonstrated that this molecule is small (<3000 Da) and hydrophilic. Conclusions: These preliminary results suggest that this new molecule, naturally produced within yeasts communities, could be a good candidate for the prevention of biofilms associated with indwelling medical devices.
New diagnostic kits on the block S179 Finding the niche of T cell assays in tuberculosis infection and disease P. Hill (Banjul, GM) In 1994 the first article describing an ‘early secreted’ antigen (esat-6) from the culture filtrate of M. tuberculosis was published. Three key
Over the last ten years unprecedented progress has been made in the treatment of HIV infection by the application of combination antiretroviral therapy (cART). Three classes of drugs have been contributed to this success: the nucleoside (NRTI) and the nonnucleoside (NNRTI) reverse transcriptase inhibitors, and the protease inhibitors (PI). With the advent of the fusion inhibitor enfuvirtide (T20) the field has been opened for new classes of drugs. During the last year a whole bundle of drugs with new targets has been studied in humans. Among the most developed compounds are CCR5 antagonists and integrase inhibitors. Other classes in earlier phases of clinical development include attachment inhibitors and maturation inhibitors. It is expected, that integrase inhibitors and CCR5- antagonists will be introduced into clinical practice in 2007/2008. Both of these drug classes have been first studied in heavily treatment experienced patients having failed NRTI, NNRTI and PI therapy. In preliminary analyses the integrase inhibitor MK-0518 combined with optimised background treatment (OBT) has shown clinical superiority over OBT alone. Up to 72% of patients treated with MK-0518 have reached complete viral suppression (HIV-RNA <50 c/mL) after 16 weeks. Preliminary data also suggest a high virological potency of the drug in treatment na¨ıve patients. MK-0518 was applied bid and was well tolerated in both pretreated an treatment na¨ıve patients. Two CCR5 antagonists are currently studied in clinical trials, maraviroc and vicriviroc. Vicriviroc together with OBT has shown superiority over OBT alone in treatment experienced patients, but has failed in a phase II study in treatment na¨ıve patients presumably due to matters of dosing. Further studies to define the optimal dose (together with ritonavir boosting) are underway. With maraviroc results of a study in treatment experienced patients exhibiting dual tropic virus (R5/X4) are available. In this population, maraviroc did not show additional virological efficacy over placebo, but lead to a greater increase of CD4 cells. In conclusion, new drugs in new classes improve the treatment options for patients with multi-resistant HIV considerably. Since these drugs
Slime wars: an in-depth look at biofilms O174 Growth, adhesion and biofilm formation of Pseudomonas aeruginosa with antibiotic-induced morphological changes under the influence of dynamic conditions
17th ECCMID / 25th ICC, Oral presentations Results: All the strains tested were able to form biofilm in all the media tested. However, differences were detected between the different media. The isolates were able to form biofilm faster in Middlebrook 7H9 (100% of surface covered in day 28 for all the strains) than in tap water (100% of surface covered in day 63 for all the strains). The day 70 none of strains covered all the surface when using PBS-5% glucose. No difference was found between species in biofilm development. Conclusions: All the NPRGM tested were able to develop biofilm in all tested media. The biofilm development is dependent on the type of the culture media, being faster when a rich media is used. No differences were detected in biofilm development among the different species. Acknowledgments: T.J. Kinnari was funded by a grant from the Academy of Finland. N. Zamora was funded by a grant from the Fundaci´on Conchita R´abago de Jim´enez D´ıaz (Madrid, Spain).
A.P. Fonseca, J.C. Sousa (Porto, PT) Objectives: The aim of this study was to investigate the effect of dynamic conditions and antibiotic-induced morphological changes on growth, adhesion and biofilm formation ability of Pseudomonas aeruginosa. Methods: A modified microtitre plate assay was used to quantify adhesion, biofilm formation and planktonic culture density of Pseudomonas aeruginosa ATCC 27853 under the effect of 0.5 Minimal Inhibitory Concentration (MIC) of Piperacillin/Tazobactam, Imipenem and Meropenem. Hydrodynamic conditions were obtained by orbital shaking at 250 rpm with the presence of a glass bead in each microtitre well. Results: These conditions decreased the adhesion and biofilm formation abilities of bacteria with antibiotic-induced morphological changes in comparison to static conditions. The planktonic culture density significantly correlates with adhesion but not with biofilm formation. Conclusion: Our results demonstrate the importance of using a high-throughput dynamic model to assess the adhesion and biofilm formation deficient behaviour of P. aeruginosa with antibiotic-induced morphological changes and suggest the possible use of sub-MIC antibiotics in clinical applications to prevent infections acquired by haematogenous spread. This dynamic model contributes to a better simulation of in vivo conditions of adhesion and biofilm formation of P. aeruginosa with altered morphologies induced by b-lactam antibiotics. Acknowledgments: This study was supported by a grant from Funda¸ca˜ o Calouste Gulbenkian (Ref. 47273).
O175 Differences in biofilm development by non-pigmented rapidly growing mycobacteria using different culture media J. Esteban, N. Zamora, R. Fernandez Roblas, I. Gadea, H. Adames, T.J. Kinnari (Madrid, ES) Objective: To evaluate the ability of different species of nonpigmented rapidly growing mycobacteria to develop biofilm in different culture media using a microtiter plate assay. Methods: Collection strains (Mycobacterium fortuitum ATCC 6841 and ATCC 13756, M. chelonae ATCC 19235 and ATCC 35752, M. abscessus DSM 44196, M. peregrinum ATCC 14467, M. mucogenicum DSM 44124, M. septicum ATCC 700731, M. immunogenum ATCC 700505, M. mageritense ATCC 700351, M. porcinum ATCC 33776, M. elephantis DSM 44368, M. smegmatis CECT 3032, CECT 3020 and CECT 3017, M. goodii ATCC 700504, M. alvei CECT 3021, and M. brumae CECT 3022) of non-pigmented rapidly growing mycobacteria (NPRGM) were inoculated in tissue culture-treated polystyrene microtiter plates and incubated in Middlebrook 7H9, PBS-5% glucose or sterile tap water. Plates were incubated at room temperature with rotation during 70 days, and media were changed each 4 days. One well for each strain and medium was stained with Fuchsin, decoloured with ethanol, and photographed to measure the biofilm development the days 1, 4, 8, 12, 20, 27, 34, 41, 48, 55, 62 and 70. Calculation of the surface covered by bacteria was performed analysing the photograps with the ImageJ software for Windows.
O176 Effect of Fe and glucose on the glycolysis and gluconeogenesis in biofilm-associated Staphylococcus epidermidis C. Massonet, V. Pintens, R. Merckx, J. Van Eldere (Leuven, BE) Objective: To determine the role of GapA (glycolysis) and GapB (gluconeogenesis) in Staphylococcus epidermidis biofilms. Methods: A biofilm-forming S. epidermidis strain from a proven catheter-related infection was used. For in vitro studies, to examine the influence of glucose, bacteria were grown overnight in BHI and re-incubated in BHI (glucose-rich; Fe-rich) or 0.9% NaCl (glucoselimited; Fe-rich). To examine the influence of iron (Fe) bacteria were grown overnight in RPMI without Fe (fRPMI) and re-incubated in fRPMI (glucose-rich; Fe-limited) or fRPMI with 25 mM Fe (glucoserich; Fe-rich). For in vivo studies a subcutaneous rat model was used. Quantification of bacteria and gene expression through Taqman PCR were performed as described by S. Vandecasteele et al. (Biochem. Biophys. Res. Commun. 2002; 291: 528–534). Extracellular matrix and bacteria were visualised through confocal laser scanning microscopy (CLSM). Results: In vitro, in a glucose-rich environment the expression of gapA and gapB did not differ between planktonic and sessile bacteria and stayed constant over time. Both in planktonic and sessile bacteria, expression of gapA was up-regulated in comparison to gapB. In vitro, in a glucose-limited environment, expression of gapA in sessile bacteria decreased in comparison to its expression in planktonic bacteria and expression of gapB in sessile bacteria increased to the expression level of gapA in sessile bacteria. In vitro, in sessile bacteria, gapB expression was high in a medium with a low Fe content, irrespective of the glucose content. Simultaneously with the increased expression of gapB, PIA production could be visualised through CLSM in sessile bacteria in all media. In vivo expression of gapA was high and remained constant over a period of two weeks. The expression of gapB decreased during the initial phase of implantation, but reached the expression level of gapA after two weeks of implantation. Conclusion: The persistent expression of gapA in sessile bacteria could indicate a role in biofilm formation, especially in the early stages, while expression levels of gapB could indicate a role in the later phases of biofilm formation. Results of gene expression and CLSM indicate a link between gapB and PIA production that is influenced by both Fe and glucose. O177 Biofilm formation may be an independent virulence factor in wild-type Staphylococcus saprophyticus strain 7108 in contrast to wild-type strain CCM 883 F. Szabados, K. Strate, M. Kaase, T. Sakinc, A. Anders, S. Gatermann (Bochum, DE) S. saprophyticus is second only to E. coli the most important causative organism of uncomplicated urinary tract infection in young female outpatients. Compared to S. aureus and S. epidermidis only very few virulence factors in S. saprophyticus have been described, for
Antiretroviral treatment example Ssp, a surface-associated lipase, Aas, an autolysin adhesin, SdrI, a collagen binding protein, and urease activity. Purportedly, the uropathogenicity of S. saprophyticus can be attributed to its ability to cope with the high range of variation in salt- and urea-concentration in human urine. The aim of this study was to elucidate virulence factors of uropathogenicity. Methods: Bacterial growth was examined under different conditions using a modified model of artificial urine as previously described. Bacterial aggregation was observed in bright light and electron micrographs. Biofilm formation was tested using native polystyrene and crystalline pre-coated microtiter plates. Results: In S. saprophyticus strain CCM 883, in contrast to wild-type strain 7108, generation-time was increased. In S. saprophyticus wild-type strains 7108 and 9325, bacterial aggregation appeared near large crystal structures in contrast to its urease negative derivative strain GJ1187 and the wild type strain CCM 883. In native polystyrene and crystalline precoated microtiter plates, biofilm formation was observed in strain 7108 in contrast to strain CCM 883. The biofilm formation in S. saprophyticus seems independent of agr-, Ssp-, SdrI, since no difference between knockout mutants to wild type strain was observed. Conclusion: Bacterial aggregation could be due to increased adhesion. The lipase activity may modulate hydrophobicity and Ca2+ binding. Higher local Ca2+ concentration, as well as strengthened bacterial aggregation, may lead to increased crystal formation. Bacteria may adhere to crystals, additionally to the later mechanism due to biofilm formation. In crystallisation process, bacteria were embedded into the crystal structure. This may be a new model of infectious stone genesis. This study strongly suggest that S. saprophyticus wild-type strain CCM 883 lacks important virulence factors in contrast to wild-type strain 7108 and biofilm formation may play an important role in S. saprophyticus urinary tract infection. O178 Production of an anti-biofilm molecule by Candida albicans yeasts growing as a biofilm
S37 properties of this antigen are that it is highly immunogenic, it is not found in BCG or many environmental mycobacteria, and it is a key virulence factor. Its immunogenicity and specificity led to a series of studies to assess its potential as a major component of new diagnostic tests. Such tests have evolved into two major forms-a whole blood assay marketed under the name Quantiferon and an ELISPOT assay marketed under the name T-spot. New antigens have been assessed for improved test performance, most notably CFP-10. Studies of in-house versions of these assays, and more recently the commercial kits, have shown encouraging results in TB cases for the diagnosis of disease and in their close contacts for the diagnosis of M. tuberculosis infection. It is clear that these tests are not confounded by prior BCG vaccination and are probably not subject to boosting by injected tuberculin. Their quantitative readouts may also provide important information with respect to infectious load. However, some findings have caused concern: disparity in test performance between temperate non-TB endemic and tropical TB-endemic settings, evidence of relatively poor sensitivity to the presence of certain M. tuberculosis strains (eg. M. africanum) and in certain sub-groups (eg. Pulmonary TB, certain TB contacts), and rapid unexplained test reversion. It is therefore becoming clear that T cell assays may have a niche in the diagnosis of certain TB cases and in certain individuals suspected of having M. tuberculosis infection, but this niche has not yet been fully defined. More longitudinal studies, especially following TB case contacts for the development of disease, are indicated. Also more studies should be undertaken in TB endemic areas. Finally, if these tests are to have any role in TB control globally they would need to be much cheaper and more easy to use. Some advances with respect to these two issues have already taken place.
Antiretroviral treatment S184 New targets for innovative HIV treatment G. F¨atkenheuer (Cologne, DE)
E. Cateau, J. Berjeaud, M. Rodier, C. Imbert (Poitiers, FR) Objectives: The influence of biofilm formation in catheter-related candidiasis has been established and it has been shown that the development of biofilm by the colonising yeasts confers resistance to antifungals. The purpose of this work was to demonstrate the production, by the Candida albicans yeasts growing as a biofilm, of a molecule able to reduce biofilm growth. Methods: An in vitro model of C. albicans biofilm associated with 100% silicone catheters was used. The supernatant medium recovered from C. albicans (ATCC 3153) biofilm aged of 24 hours was added during the course of a new biofilm formation made with 4 C. albicans strains (182, 444, 2091 and ATCC 3153), and its influence was subsequently evaluated with XTT method. Ultrafiltration and purification assays to characterise the modulating fungal molecule responsible for the biofilm supernatant activity are presented in this study. Results: The addition of the supernatant to adherent C. albicans cells induced a significant (p < 0.001) inhibition of the biofilm growth. This activity was not observed when the supernatant was added to preformed biofilms. Ultrafiltration and purification assays demonstrated that this molecule is small (<3000 Da) and hydrophilic. Conclusions: These preliminary results suggest that this new molecule, naturally produced within yeasts communities, could be a good candidate for the prevention of biofilms associated with indwelling medical devices.
New diagnostic kits on the block S179 Finding the niche of T cell assays in tuberculosis infection and disease P. Hill (Banjul, GM) In 1994 the first article describing an ‘early secreted’ antigen (esat-6) from the culture filtrate of M. tuberculosis was published. Three key
Over the last ten years unprecedented progress has been made in the treatment of HIV infection by the application of combination antiretroviral therapy (cART). Three classes of drugs have been contributed to this success: the nucleoside (NRTI) and the nonnucleoside (NNRTI) reverse transcriptase inhibitors, and the protease inhibitors (PI). With the advent of the fusion inhibitor enfuvirtide (T20) the field has been opened for new classes of drugs. During the last year a whole bundle of drugs with new targets has been studied in humans. Among the most developed compounds are CCR5 antagonists and integrase inhibitors. Other classes in earlier phases of clinical development include attachment inhibitors and maturation inhibitors. It is expected, that integrase inhibitors and CCR5- antagonists will be introduced into clinical practice in 2007/2008. Both of these drug classes have been first studied in heavily treatment experienced patients having failed NRTI, NNRTI and PI therapy. In preliminary analyses the integrase inhibitor MK-0518 combined with optimised background treatment (OBT) has shown clinical superiority over OBT alone. Up to 72% of patients treated with MK-0518 have reached complete viral suppression (HIV-RNA <50 c/mL) after 16 weeks. Preliminary data also suggest a high virological potency of the drug in treatment na¨ıve patients. MK-0518 was applied bid and was well tolerated in both pretreated an treatment na¨ıve patients. Two CCR5 antagonists are currently studied in clinical trials, maraviroc and vicriviroc. Vicriviroc together with OBT has shown superiority over OBT alone in treatment experienced patients, but has failed in a phase II study in treatment na¨ıve patients presumably due to matters of dosing. Further studies to define the optimal dose (together with ritonavir boosting) are underway. With maraviroc results of a study in treatment experienced patients exhibiting dual tropic virus (R5/X4) are available. In this population, maraviroc did not show additional virological efficacy over placebo, but lead to a greater increase of CD4 cells. In conclusion, new drugs in new classes improve the treatment options for patients with multi-resistant HIV considerably. Since these drugs