The alarming threat of the spread of multidrug resistant bacteria currently leaves clinicians wit... more The alarming threat of the spread of multidrug resistant bacteria currently leaves clinicians with very limited options to combat infections, especially those from Gram-negative bacteria. Hence, innovative strategies to deliver the next generation of antibacterials are urgently needed. Penicillin binding proteins (PBPs) are proven targets inhibited by β-lactam antibiotics. To discover novel, non-β-lactam inhibitors against PBP3 of Pseudomonas aeruginosa, we optimised a fluorescence assay based on a well-known thioester artificial substrate and performed a target screening using a focused protease-targeted library of 2455 compounds, which led to the identification of pyrrolidine-2,3-dione as a potential scaffold to inhibit the PBP3 target. Further chemical optimisation using a one-pot three-component reaction protocol delivered compounds with excellent target inhibition, initial antibacterial activities against P. aeruginosa and no apparent cytotoxicity. Our investigation revealed th...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Bio®lm formation by Staphylococcus aureus is a serious problem in nosocomial infections. There ar... more Bio®lm formation by Staphylococcus aureus is a serious problem in nosocomial infections. There are great differences in the capacity of S. aureus to express bio®lms, but the reasons are unknown. In all, 105 S. aureus strains were tested for a correlation between the agr quorum-sensing system phenotype and the ability of S. aureus to adhere to polystyrene. Some 78 % of agr-negative, but only 6 % of agr-positive, strains formed a bio®lm, demonstrating a profound impact of agr on bio®lm formation. This result was con®rmed with de®ned agr mutants and by inhibition of agr with quorum-sensing blockers. The observed effect was not due to dif-ferential expression of the autolysin Atl or of the exopolysaccharide polysaccharide intercel-lular adhesin but seemed to be caused, at least in part, by the surfactant properties of d-toxin. The detected bio®lm-enhancing effect of S. aureus quorum-sensing blockers call into question the proposed therapeutic use of such substances. Staphylococcus aureu...
Recently, Staphylococcus aureus strains with intermediate resistance to vancomycin, the antibioti... more Recently, Staphylococcus aureus strains with intermediate resistance to vancomycin, the antibiotic of last resort, have been described. Multiple changes in peptidoglycan turnover and structure contribute to the resistance phenotype. Here, we describe that structural changes of teichoic acids in the cell envelope have a considerable influence on the susceptibility to vancomycin and other glycopeptides. S. aureus cells lacking D-alanine esters in teichoic acids exhibited an at least threefold-increased sensitivity to glycopeptide antibiotics. Furthermore, the autolytic activity of the D-alanine mutant was reduced compared to the wild-type, and the mutant was more susceptible to the staphylolytic enzyme lysostaphin. Vancomycin inhibited autolysis at very high concentrations but neither in the wild-type nor in the mutant was the autolytic activity influenced in the range of the MIC. Mutant cells had a considerably higher capacity to bind vancomycin.
Hospital readmissions following severe infections are a major economic burden on the health care ... more Hospital readmissions following severe infections are a major economic burden on the health care system and have a negative influence on patients' quality of life. Understanding the risk factors for readmission, particularly the extent to which they could be prevented, is of a great importance. In this study we evaluated potentially preventable risk factors for 60-day readmission in patients surviving hospitalization for complicated urinary tract infection (cUTI). This was a multinational, multicentre retrospective cohort study conducted in Europe and the Middle East. Our cohort included survivors of hospitalization due to cUTI during the years 2013–2014. The primary outcome was 60-day readmission following index hospitalization. Patient characteristics that could have influenced readmission: demographics, infection presentation and management, microbiological and clinical data; were collected via computerized medical records from infection onset up to 60 days after hospital dis...
ObjectivesTo systematically summarize the evidence on how to collect, analyse and report antimicr... more ObjectivesTo systematically summarize the evidence on how to collect, analyse and report antimicrobial resistance (AMR) surveillance data to inform antimicrobial stewardship (AMS) teams providing guidance on empirical antibiotic treatment in healthcare settings.MethodsThe research group identified 10 key questions about the link between AMR surveillance and AMS using a checklist of 9 elements for good practice in health research priority settings and a modified 3D combined approach matrix, and conducted a systematic review of published original studies and guidelines on the link between AMR surveillance and AMS.ResultsThe questions identified focused on AMS team composition; minimum infrastructure requirements for AMR surveillance; organisms, samples and susceptibility patterns to report; data stratification strategies; reporting frequency; resistance thresholds to drive empirical therapy; surveillance in high-risk hospital units, long-term care, outpatient and veterinary settings; ...
Antimicrobial Resistance & Infection Control, 2019
Background Although catheter-associated urinary tract infection (CA-UTI) is a major healthcare-re... more Background Although catheter-associated urinary tract infection (CA-UTI) is a major healthcare-related problem worldwide, there is a scarcity of current data from countries with high antimicrobial resistance rates. We aimed to determine the clinical outcomes of patients with CA-UTI compared to those of patients with other sources of complicated urinary tract infection (cUTI), and to assess the impact of antimicrobial resistance. We also aimed to identify the factors influencing 30-day mortality among patients with CA-UTI. Methods This was a multicentre, multinational retrospective cohort study including hospitalised adults with cUTI between January 2013 and December 2014 in twenty hospitals from eight countries from southern Europe, Turkey and Israel. The primary endpoint was 30-day mortality. The secondary endpoints were length of hospital stay, symptom improvement after 7 days’ treatment, symptom recurrence at 30 days and readmission 60 days after hospital discharge. Results Of th...
Purpose: Complicated urinary tract infections (cUTIs) are among the most frequent healthcare-asso... more Purpose: Complicated urinary tract infections (cUTIs) are among the most frequent healthcare-associated infections. In patients with cUTI, Pseudomonas aeruginosa deserves special attention, since it can affect patients with serious underlying conditions. Our aim was to gain insight into the risk factors and prognosis of P. aeruginosa cUTIs in a scenario of increasing multidrug resistance (MDR). Methods: This was a multinational, retrospective, observational study at 20 hospitals in south and southeastern Europe, Turkey, and Israel including consecutive patients with cUTI hospitalized between January 2013 and December 2014. A mixed-effect logistic regression model was performed to assess risk factors for P. aeruginosa and MDR P. aeruginosa cUTI. Results: Of 1,007 episodes of cUTI, 97 (9.6%) were due to P. aeruginosa. Resistance rates of P. aeruginosa were: antipseudomonal cephalosporins 35 of 97 (36.1%), aminoglycosides 30 of 97 (30.9%), piperacillin-tazobactam 21 of 97 (21.6%), fluoroquinolones 43 of 97 (44.3%), and carbapenems 28 of 97 (28.8%). The MDR rate was 28 of 97 (28.8%). Independent risk factors for P. aeruginosa cUTI were male sex (OR 2.61, 95% CI 1.60-4.27), steroid therapy (OR 2.40, 95% CI 1.10-5.27), bedridden functional status (OR 1.79, 95% CI 0.99-3.25), antibiotic treatment within the previous 30 days (OR 2.34, 95% CI 1.38-3.94), indwelling urinary catheter (OR 2.41, 95% CI 1.43-4.08), and procedures that anatomically modified the urinary tract (OR 2.01, 95% CI 1.04-3.87). Independent risk factors for MDR P. aeruginosa cUTI were age (OR 0.96, 95% CI 0.93-0.99) and anatomical urinary tract modification (OR 4.75, 95% CI 1.06-21.26). Readmission was higher in P. aeruginosa cUTI patients than in other etiologies (23 of 97 [23.7%] vs 144 of 910 [15.8%], P=0.04), while 30-day mortality was not significantly different (seven of 97 [7.2%] vs 77 of 910 [8.5%], P=0.6). Conclusion: Patients with P. aeruginosa cUTI had characteristically a serious baseline condition and manipulation of the urinary tract, although their mortality was not higher than that of patients with cUTI caused by other etiologies.
The Journal of antimicrobial chemotherapy, Jan 15, 2015
Antibiotic resistance (ABR) is a global public health threat. Despite the emergence of highly res... more Antibiotic resistance (ABR) is a global public health threat. Despite the emergence of highly resistant organisms and the huge medical need for new drugs, the development of antibacterials has slowed to an unacceptable level worldwide. Numerous government and non-government agencies have called for public-private partnerships and innovative funding mechanisms to address this problem. To respond to this public health crisis, the Innovative Medicines Initiative Joint Undertaking programme has invested more than €660 million, with a goal of matched contributions from the European Commission and the European Federation of Pharmaceutical Industries and Associations, in the development of new antibacterial strategies. The New Drugs for Bad Bugs (ND4BB) programme, an Innovative Medicines Initiative, has the ultimate goal to boost the fight against ABR at every level from basic science and drug discovery, through clinical development to new business models and responsible use of antibiotics...
Biofilms play an important role in many chronic bacterial infections. Production of an extracellu... more Biofilms play an important role in many chronic bacterial infections. Production of an extracellular mixture of sugar polymers called exopolysaccharide is characteristic and critical for biofilm formation. However, there is limited information about the mechanisms involved in the biosynthesis and modification of exopolysaccharide components and how these processes influence bacterial pathogenesis. Staphylococcus epidermidis is an important human pathogen that frequently causes persistent infections by biofilm formation on indwelling medical devices. It produces a poly-N-acetylglucosamine molecule that emerges as an exopolysaccharide component of many bacterial pathogens. Using a novel method based on size exclusion chromatography-mass spectrometry, we demonstrate that the surface-attached protein IcaB is responsible for deacetylation of the poly-N-acetylglucosamine molecule. Most likely due to the loss of its cationic character, non-deacetylated poly-acetylglucosamine in an isogenic icaB mutant strain was devoid of the ability to attach to the bacterial cell surface. Importantly, deacetylation of the polymer was essential for key virulence mechanisms of S. epidermidis, namely biofilm formation, colonization, and resistance to neutrophil phagocytosis and human antibacterial peptides. Furthermore, persistence of the icaB mutant strain was significantly impaired in a murine model of device-related infection. This is the first study to describe a mechanism of exopolysaccharide modification that is indispensable for the development of biofilm-associated human disease. Notably, this general virulence mechanism is likely similar for other pathogenic bacteria and constitutes an excellent target for therapeutic maneuvers aimed at combating biofilmassociated infection.
Nosocomial infections caused by Staphylococcus epidermidis are characterized by biofilm formation... more Nosocomial infections caused by Staphylococcus epidermidis are characterized by biofilm formation on implanted medical devices. Quorum-sensing regulation plays a major role in the biofilm development of many bacterial pathogens. Here, we describe luxS , a quorum-sensing system in staphylococci that has a significant impact on biofilm development and virulence. We constructed an isogenic ΔluxS mutant strain of a biofilm-forming clinical isolate of S. epidermidis and demonstrated that luxS signaling is functional in S. epidermidis . The mutant strain showed increased biofilm formation in vitro and enhanced virulence in a rat model of biofilm-associated infection. Genetic complementation and addition of autoinducer 2-containing culture filtrate restored the wild-type phenotype, demonstrating that luxS repressed biofilm formation through a cell-cell signaling mechanism based on autoinducer 2 secretion. Enhanced production of the biofilm exopolysaccharide polysaccharide intercellular adh...
To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide int... more To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide intercellular adhesin, whose biosynthesis is driven by the ica locus, a plasmid containing the ica locus was transferred to three ica -negative strains. Using in vitro biofilm assays and a rat central venous catheter infection model, we confirmed the importance of the ica locus for biofilm production and pathogenesis of S. epidermidis .
Novel antimicrobial strategies are urgently required because of the rising threat of multi drug r... more Novel antimicrobial strategies are urgently required because of the rising threat of multi drug resistant bacterial strains and the infections caused by them. Among the available target structures, the so-called penicillin binding proteins are of particular interest, owing to their good accessibility in the periplasmic space, and the lack of homologous proteins in humans, reducing the risk of side effects of potential drugs. In this report, we focus on the interaction of the innovative β-lactam antibiotic AIC499 with penicillin binding protein 3 (PBP3) from Escherichia coli and Pseudomonas aeruginosa. This recently developed monobactam displays broad antimicrobial activity, against Gram-negative strains, and improved resistance to most classes of β-lactamases. By analyzing crystal structures of the respective complexes, we were able to explore the binding mode of AIC499 to its target proteins. In addition, the apo structures determined for PBP3, from P. aeruginosa and the catalytic ...
Antimicrobial resistance and infection control, 2018
Patients with complicated urinary tract infections (cUTIs) frequently receive broad-spectrum anti... more Patients with complicated urinary tract infections (cUTIs) frequently receive broad-spectrum antibiotics. We aimed to determine the prevalence and predictive factors of multidrug-resistant gram-negative bacteria in patients with cUTI. This is a multicenter, retrospective cohort study in south and eastern Europe, Turkey and Israel including consecutive patients with cUTIs hospitalised between January 2013 and December 2014. Multidrug-resistance was defined as non-susceptibility to at least one agent in three or more antimicrobial categories. A mixed-effects logistic regression model was used to determine predictive factors of multidrug-resistant gram-negative bacteria cUTI. From 948 patients and 1074 microbiological isolates, was the most frequent microorganism (559/1074), showing a 14.5% multidrug-resistance rate. was second (168/1074) and exhibited the highest multidrug-resistance rate (54.2%), followed by (97/1074) with a 38.1% multidrug-resistance rate. Predictors of multidrug-re...
Complicated urinary tract infections (cUTIs) impose a high burden on healthcare systems and are a... more Complicated urinary tract infections (cUTIs) impose a high burden on healthcare systems and are a frequent cause of hospitalisation. The aims of this paper are to estimate the cost per episode of patients hospitalised due to cUTI and to explore the factors associated with cUTI-related healthcare costs in eight countries with high prevalence of multidrug resistance (MDR). This is a multinational observational, retrospective study. The mean cost per episode was computed by multiplying the volume of healthcare use for each patient by the unit cost of each item of care and summing across all components. Costs were measured from the hospital perspective. Patient-level regression analyses were used to identify the factors explaining variation in cUTI-related costs. The study was conducted in 20 hospitals in eight countries with high prevalence of multidrug resistant Gram-negative bacteria (Bulgaria, Greece, Hungary, Israel, Italy, Romania, Spain and Turkey). Data were obtained from 644 ep...
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, Jan 17, 2018
Complicated urinary tract infections (cUTIs) are responsible for a major share of all antibiotic ... more Complicated urinary tract infections (cUTIs) are responsible for a major share of all antibiotic consumption in hospitals. We aim to describe risk factors for treatment failure and mortality among hospitalised patients with cUTIs. A multinational, multicentre retrospective cohort study, conducted in 20 countries in Europe and the Middle East. Data were collected from patients' files on hospitalised patients with a diagnosis of cUTI during 2013-2014. The primary outcome was treatment failure. Secondary outcomes included all-cause mortality 30 days, among other outcomes. Multivariable analysis using a logistic model and the hospital as a random variable was performed to identify independent predictors for treatment failure and 30 day mortality. A total of 981 patients with cUTI were included. Treatment failure was observed in 26.6% (261/981) of patients; all cause 30-day mortality rate was 8.7% (85/976), most of these in patients with catheter related UTI (CaUTI). Risk factors for...
Antimicrobial resistance poses a growing threat to public health and the provision of health care... more Antimicrobial resistance poses a growing threat to public health and the provision of health care. Its surveillance should provide up-to-date and relevant information to monitor the appropriateness of therapy guidelines, antibiotic formulary, antibiotic stewardship programmes, public health interventions, infection control policies, and antimicrobial development. In Europe, although the European Antimicrobial Resistance Surveillance Network provides annual reports on monitored resistant bacteria, national surveillance efforts are still fragmented and heterogeneous, and have substantial structural problems and issues with laboratory data. Most incidence and prevalence data cannot be linked with relevant epidemiological, clinical, or outcome data. Genetic typing, to establish whether trends of antimicrobial resistance are caused by spread of resistant strains or by transfer of resistance determinants among different strains and species, is not routinely done. Furthermore, laboratory-b...
Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases, Jan 24, 2017
Surveillance is a key component of any control strategy for health-care associated infections (HA... more Surveillance is a key component of any control strategy for health-care associated infections (HAIs) and antimicrobial resistance (AMR), and public availability of methodological aspects is crucial for the interpretation of the data. We sought to systematically review publicly available information for HAIs and/or AMR surveillance systems organised by public institutions or scientific societies in European countries. A systematic review of scientific and grey literature following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines was performed. Information on HAIs and/or AMR surveillance systems published until October 31, 2016 were included. 112 surveillance systems were detected; 56 from 20 countries were finally included. Most exclusions were due to lack of publicly available information. Regarding antimicrobial resistance, the most frequent indicator was the proportion of resistant isolates (27 of 34 providing information, 79.42%); only 18...
RWRWRW-NH 2 (MP196) is an amphipathic hexapeptide that targets the bacterial cytoplasmic membrane... more RWRWRW-NH 2 (MP196) is an amphipathic hexapeptide that targets the bacterial cytoplasmic membrane and inhibits cellular respiration and cell wall synthesis. In previous studies it showed promising activity against Gram-positive bacteria and no significant cytotoxicity or hemolysis. MP196 is therefore used as lead structure for developing more potent antibiotic derivatives. Here we present a more comprehensive study on the parent peptide MP196 with regard to clinically relevant parameters. We found that MP196 acts rapidly bactericidal killing 97% of initial CFU within 10 min at two times MIC. We were unable to detect resistance in standard 24 and 48 h resistance frequency assays. However, MP196 was effective against some but not all MRSA and VISA strains. Serum binding of MP196 was intermediate and we confirmed its low toxicity against mammalian cell lines. MP196 did neither induce NFκB activation nor cause an increase in IL8 levels at 250 µg/mL, and no IgE-dependent activation of basophil granulocytes was detected at 500 µg/mL. Yet, MP196 demonstrated acute toxicity in mice upon injection into the blood stream. Phase contrast microscopy of mouse blood treated with MP196 revealed a shrinking of erythrocytes at 250 µg/mL and severe morphological changes and lysis of erythrocytes at 500 µg/mL. These data suggest that MP196 derivatization directed at further lowering hemolysis could be instrumental in overcoming acute toxicity. The assessment of hemolysis is a critical step in the evaluation of the clinical potential of promising antimicrobial peptides and should be accompanied by microscopy-based morphological analysis of blood cells.
The alarming threat of the spread of multidrug resistant bacteria currently leaves clinicians wit... more The alarming threat of the spread of multidrug resistant bacteria currently leaves clinicians with very limited options to combat infections, especially those from Gram-negative bacteria. Hence, innovative strategies to deliver the next generation of antibacterials are urgently needed. Penicillin binding proteins (PBPs) are proven targets inhibited by β-lactam antibiotics. To discover novel, non-β-lactam inhibitors against PBP3 of Pseudomonas aeruginosa, we optimised a fluorescence assay based on a well-known thioester artificial substrate and performed a target screening using a focused protease-targeted library of 2455 compounds, which led to the identification of pyrrolidine-2,3-dione as a potential scaffold to inhibit the PBP3 target. Further chemical optimisation using a one-pot three-component reaction protocol delivered compounds with excellent target inhibition, initial antibacterial activities against P. aeruginosa and no apparent cytotoxicity. Our investigation revealed th...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Bio®lm formation by Staphylococcus aureus is a serious problem in nosocomial infections. There ar... more Bio®lm formation by Staphylococcus aureus is a serious problem in nosocomial infections. There are great differences in the capacity of S. aureus to express bio®lms, but the reasons are unknown. In all, 105 S. aureus strains were tested for a correlation between the agr quorum-sensing system phenotype and the ability of S. aureus to adhere to polystyrene. Some 78 % of agr-negative, but only 6 % of agr-positive, strains formed a bio®lm, demonstrating a profound impact of agr on bio®lm formation. This result was con®rmed with de®ned agr mutants and by inhibition of agr with quorum-sensing blockers. The observed effect was not due to dif-ferential expression of the autolysin Atl or of the exopolysaccharide polysaccharide intercel-lular adhesin but seemed to be caused, at least in part, by the surfactant properties of d-toxin. The detected bio®lm-enhancing effect of S. aureus quorum-sensing blockers call into question the proposed therapeutic use of such substances. Staphylococcus aureu...
Recently, Staphylococcus aureus strains with intermediate resistance to vancomycin, the antibioti... more Recently, Staphylococcus aureus strains with intermediate resistance to vancomycin, the antibiotic of last resort, have been described. Multiple changes in peptidoglycan turnover and structure contribute to the resistance phenotype. Here, we describe that structural changes of teichoic acids in the cell envelope have a considerable influence on the susceptibility to vancomycin and other glycopeptides. S. aureus cells lacking D-alanine esters in teichoic acids exhibited an at least threefold-increased sensitivity to glycopeptide antibiotics. Furthermore, the autolytic activity of the D-alanine mutant was reduced compared to the wild-type, and the mutant was more susceptible to the staphylolytic enzyme lysostaphin. Vancomycin inhibited autolysis at very high concentrations but neither in the wild-type nor in the mutant was the autolytic activity influenced in the range of the MIC. Mutant cells had a considerably higher capacity to bind vancomycin.
Hospital readmissions following severe infections are a major economic burden on the health care ... more Hospital readmissions following severe infections are a major economic burden on the health care system and have a negative influence on patients' quality of life. Understanding the risk factors for readmission, particularly the extent to which they could be prevented, is of a great importance. In this study we evaluated potentially preventable risk factors for 60-day readmission in patients surviving hospitalization for complicated urinary tract infection (cUTI). This was a multinational, multicentre retrospective cohort study conducted in Europe and the Middle East. Our cohort included survivors of hospitalization due to cUTI during the years 2013–2014. The primary outcome was 60-day readmission following index hospitalization. Patient characteristics that could have influenced readmission: demographics, infection presentation and management, microbiological and clinical data; were collected via computerized medical records from infection onset up to 60 days after hospital dis...
ObjectivesTo systematically summarize the evidence on how to collect, analyse and report antimicr... more ObjectivesTo systematically summarize the evidence on how to collect, analyse and report antimicrobial resistance (AMR) surveillance data to inform antimicrobial stewardship (AMS) teams providing guidance on empirical antibiotic treatment in healthcare settings.MethodsThe research group identified 10 key questions about the link between AMR surveillance and AMS using a checklist of 9 elements for good practice in health research priority settings and a modified 3D combined approach matrix, and conducted a systematic review of published original studies and guidelines on the link between AMR surveillance and AMS.ResultsThe questions identified focused on AMS team composition; minimum infrastructure requirements for AMR surveillance; organisms, samples and susceptibility patterns to report; data stratification strategies; reporting frequency; resistance thresholds to drive empirical therapy; surveillance in high-risk hospital units, long-term care, outpatient and veterinary settings; ...
Antimicrobial Resistance & Infection Control, 2019
Background Although catheter-associated urinary tract infection (CA-UTI) is a major healthcare-re... more Background Although catheter-associated urinary tract infection (CA-UTI) is a major healthcare-related problem worldwide, there is a scarcity of current data from countries with high antimicrobial resistance rates. We aimed to determine the clinical outcomes of patients with CA-UTI compared to those of patients with other sources of complicated urinary tract infection (cUTI), and to assess the impact of antimicrobial resistance. We also aimed to identify the factors influencing 30-day mortality among patients with CA-UTI. Methods This was a multicentre, multinational retrospective cohort study including hospitalised adults with cUTI between January 2013 and December 2014 in twenty hospitals from eight countries from southern Europe, Turkey and Israel. The primary endpoint was 30-day mortality. The secondary endpoints were length of hospital stay, symptom improvement after 7 days’ treatment, symptom recurrence at 30 days and readmission 60 days after hospital discharge. Results Of th...
Purpose: Complicated urinary tract infections (cUTIs) are among the most frequent healthcare-asso... more Purpose: Complicated urinary tract infections (cUTIs) are among the most frequent healthcare-associated infections. In patients with cUTI, Pseudomonas aeruginosa deserves special attention, since it can affect patients with serious underlying conditions. Our aim was to gain insight into the risk factors and prognosis of P. aeruginosa cUTIs in a scenario of increasing multidrug resistance (MDR). Methods: This was a multinational, retrospective, observational study at 20 hospitals in south and southeastern Europe, Turkey, and Israel including consecutive patients with cUTI hospitalized between January 2013 and December 2014. A mixed-effect logistic regression model was performed to assess risk factors for P. aeruginosa and MDR P. aeruginosa cUTI. Results: Of 1,007 episodes of cUTI, 97 (9.6%) were due to P. aeruginosa. Resistance rates of P. aeruginosa were: antipseudomonal cephalosporins 35 of 97 (36.1%), aminoglycosides 30 of 97 (30.9%), piperacillin-tazobactam 21 of 97 (21.6%), fluoroquinolones 43 of 97 (44.3%), and carbapenems 28 of 97 (28.8%). The MDR rate was 28 of 97 (28.8%). Independent risk factors for P. aeruginosa cUTI were male sex (OR 2.61, 95% CI 1.60-4.27), steroid therapy (OR 2.40, 95% CI 1.10-5.27), bedridden functional status (OR 1.79, 95% CI 0.99-3.25), antibiotic treatment within the previous 30 days (OR 2.34, 95% CI 1.38-3.94), indwelling urinary catheter (OR 2.41, 95% CI 1.43-4.08), and procedures that anatomically modified the urinary tract (OR 2.01, 95% CI 1.04-3.87). Independent risk factors for MDR P. aeruginosa cUTI were age (OR 0.96, 95% CI 0.93-0.99) and anatomical urinary tract modification (OR 4.75, 95% CI 1.06-21.26). Readmission was higher in P. aeruginosa cUTI patients than in other etiologies (23 of 97 [23.7%] vs 144 of 910 [15.8%], P=0.04), while 30-day mortality was not significantly different (seven of 97 [7.2%] vs 77 of 910 [8.5%], P=0.6). Conclusion: Patients with P. aeruginosa cUTI had characteristically a serious baseline condition and manipulation of the urinary tract, although their mortality was not higher than that of patients with cUTI caused by other etiologies.
The Journal of antimicrobial chemotherapy, Jan 15, 2015
Antibiotic resistance (ABR) is a global public health threat. Despite the emergence of highly res... more Antibiotic resistance (ABR) is a global public health threat. Despite the emergence of highly resistant organisms and the huge medical need for new drugs, the development of antibacterials has slowed to an unacceptable level worldwide. Numerous government and non-government agencies have called for public-private partnerships and innovative funding mechanisms to address this problem. To respond to this public health crisis, the Innovative Medicines Initiative Joint Undertaking programme has invested more than €660 million, with a goal of matched contributions from the European Commission and the European Federation of Pharmaceutical Industries and Associations, in the development of new antibacterial strategies. The New Drugs for Bad Bugs (ND4BB) programme, an Innovative Medicines Initiative, has the ultimate goal to boost the fight against ABR at every level from basic science and drug discovery, through clinical development to new business models and responsible use of antibiotics...
Biofilms play an important role in many chronic bacterial infections. Production of an extracellu... more Biofilms play an important role in many chronic bacterial infections. Production of an extracellular mixture of sugar polymers called exopolysaccharide is characteristic and critical for biofilm formation. However, there is limited information about the mechanisms involved in the biosynthesis and modification of exopolysaccharide components and how these processes influence bacterial pathogenesis. Staphylococcus epidermidis is an important human pathogen that frequently causes persistent infections by biofilm formation on indwelling medical devices. It produces a poly-N-acetylglucosamine molecule that emerges as an exopolysaccharide component of many bacterial pathogens. Using a novel method based on size exclusion chromatography-mass spectrometry, we demonstrate that the surface-attached protein IcaB is responsible for deacetylation of the poly-N-acetylglucosamine molecule. Most likely due to the loss of its cationic character, non-deacetylated poly-acetylglucosamine in an isogenic icaB mutant strain was devoid of the ability to attach to the bacterial cell surface. Importantly, deacetylation of the polymer was essential for key virulence mechanisms of S. epidermidis, namely biofilm formation, colonization, and resistance to neutrophil phagocytosis and human antibacterial peptides. Furthermore, persistence of the icaB mutant strain was significantly impaired in a murine model of device-related infection. This is the first study to describe a mechanism of exopolysaccharide modification that is indispensable for the development of biofilm-associated human disease. Notably, this general virulence mechanism is likely similar for other pathogenic bacteria and constitutes an excellent target for therapeutic maneuvers aimed at combating biofilmassociated infection.
Nosocomial infections caused by Staphylococcus epidermidis are characterized by biofilm formation... more Nosocomial infections caused by Staphylococcus epidermidis are characterized by biofilm formation on implanted medical devices. Quorum-sensing regulation plays a major role in the biofilm development of many bacterial pathogens. Here, we describe luxS , a quorum-sensing system in staphylococci that has a significant impact on biofilm development and virulence. We constructed an isogenic ΔluxS mutant strain of a biofilm-forming clinical isolate of S. epidermidis and demonstrated that luxS signaling is functional in S. epidermidis . The mutant strain showed increased biofilm formation in vitro and enhanced virulence in a rat model of biofilm-associated infection. Genetic complementation and addition of autoinducer 2-containing culture filtrate restored the wild-type phenotype, demonstrating that luxS repressed biofilm formation through a cell-cell signaling mechanism based on autoinducer 2 secretion. Enhanced production of the biofilm exopolysaccharide polysaccharide intercellular adh...
To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide int... more To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide intercellular adhesin, whose biosynthesis is driven by the ica locus, a plasmid containing the ica locus was transferred to three ica -negative strains. Using in vitro biofilm assays and a rat central venous catheter infection model, we confirmed the importance of the ica locus for biofilm production and pathogenesis of S. epidermidis .
Novel antimicrobial strategies are urgently required because of the rising threat of multi drug r... more Novel antimicrobial strategies are urgently required because of the rising threat of multi drug resistant bacterial strains and the infections caused by them. Among the available target structures, the so-called penicillin binding proteins are of particular interest, owing to their good accessibility in the periplasmic space, and the lack of homologous proteins in humans, reducing the risk of side effects of potential drugs. In this report, we focus on the interaction of the innovative β-lactam antibiotic AIC499 with penicillin binding protein 3 (PBP3) from Escherichia coli and Pseudomonas aeruginosa. This recently developed monobactam displays broad antimicrobial activity, against Gram-negative strains, and improved resistance to most classes of β-lactamases. By analyzing crystal structures of the respective complexes, we were able to explore the binding mode of AIC499 to its target proteins. In addition, the apo structures determined for PBP3, from P. aeruginosa and the catalytic ...
Antimicrobial resistance and infection control, 2018
Patients with complicated urinary tract infections (cUTIs) frequently receive broad-spectrum anti... more Patients with complicated urinary tract infections (cUTIs) frequently receive broad-spectrum antibiotics. We aimed to determine the prevalence and predictive factors of multidrug-resistant gram-negative bacteria in patients with cUTI. This is a multicenter, retrospective cohort study in south and eastern Europe, Turkey and Israel including consecutive patients with cUTIs hospitalised between January 2013 and December 2014. Multidrug-resistance was defined as non-susceptibility to at least one agent in three or more antimicrobial categories. A mixed-effects logistic regression model was used to determine predictive factors of multidrug-resistant gram-negative bacteria cUTI. From 948 patients and 1074 microbiological isolates, was the most frequent microorganism (559/1074), showing a 14.5% multidrug-resistance rate. was second (168/1074) and exhibited the highest multidrug-resistance rate (54.2%), followed by (97/1074) with a 38.1% multidrug-resistance rate. Predictors of multidrug-re...
Complicated urinary tract infections (cUTIs) impose a high burden on healthcare systems and are a... more Complicated urinary tract infections (cUTIs) impose a high burden on healthcare systems and are a frequent cause of hospitalisation. The aims of this paper are to estimate the cost per episode of patients hospitalised due to cUTI and to explore the factors associated with cUTI-related healthcare costs in eight countries with high prevalence of multidrug resistance (MDR). This is a multinational observational, retrospective study. The mean cost per episode was computed by multiplying the volume of healthcare use for each patient by the unit cost of each item of care and summing across all components. Costs were measured from the hospital perspective. Patient-level regression analyses were used to identify the factors explaining variation in cUTI-related costs. The study was conducted in 20 hospitals in eight countries with high prevalence of multidrug resistant Gram-negative bacteria (Bulgaria, Greece, Hungary, Israel, Italy, Romania, Spain and Turkey). Data were obtained from 644 ep...
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, Jan 17, 2018
Complicated urinary tract infections (cUTIs) are responsible for a major share of all antibiotic ... more Complicated urinary tract infections (cUTIs) are responsible for a major share of all antibiotic consumption in hospitals. We aim to describe risk factors for treatment failure and mortality among hospitalised patients with cUTIs. A multinational, multicentre retrospective cohort study, conducted in 20 countries in Europe and the Middle East. Data were collected from patients' files on hospitalised patients with a diagnosis of cUTI during 2013-2014. The primary outcome was treatment failure. Secondary outcomes included all-cause mortality 30 days, among other outcomes. Multivariable analysis using a logistic model and the hospital as a random variable was performed to identify independent predictors for treatment failure and 30 day mortality. A total of 981 patients with cUTI were included. Treatment failure was observed in 26.6% (261/981) of patients; all cause 30-day mortality rate was 8.7% (85/976), most of these in patients with catheter related UTI (CaUTI). Risk factors for...
Antimicrobial resistance poses a growing threat to public health and the provision of health care... more Antimicrobial resistance poses a growing threat to public health and the provision of health care. Its surveillance should provide up-to-date and relevant information to monitor the appropriateness of therapy guidelines, antibiotic formulary, antibiotic stewardship programmes, public health interventions, infection control policies, and antimicrobial development. In Europe, although the European Antimicrobial Resistance Surveillance Network provides annual reports on monitored resistant bacteria, national surveillance efforts are still fragmented and heterogeneous, and have substantial structural problems and issues with laboratory data. Most incidence and prevalence data cannot be linked with relevant epidemiological, clinical, or outcome data. Genetic typing, to establish whether trends of antimicrobial resistance are caused by spread of resistant strains or by transfer of resistance determinants among different strains and species, is not routinely done. Furthermore, laboratory-b...
Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases, Jan 24, 2017
Surveillance is a key component of any control strategy for health-care associated infections (HA... more Surveillance is a key component of any control strategy for health-care associated infections (HAIs) and antimicrobial resistance (AMR), and public availability of methodological aspects is crucial for the interpretation of the data. We sought to systematically review publicly available information for HAIs and/or AMR surveillance systems organised by public institutions or scientific societies in European countries. A systematic review of scientific and grey literature following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines was performed. Information on HAIs and/or AMR surveillance systems published until October 31, 2016 were included. 112 surveillance systems were detected; 56 from 20 countries were finally included. Most exclusions were due to lack of publicly available information. Regarding antimicrobial resistance, the most frequent indicator was the proportion of resistant isolates (27 of 34 providing information, 79.42%); only 18...
RWRWRW-NH 2 (MP196) is an amphipathic hexapeptide that targets the bacterial cytoplasmic membrane... more RWRWRW-NH 2 (MP196) is an amphipathic hexapeptide that targets the bacterial cytoplasmic membrane and inhibits cellular respiration and cell wall synthesis. In previous studies it showed promising activity against Gram-positive bacteria and no significant cytotoxicity or hemolysis. MP196 is therefore used as lead structure for developing more potent antibiotic derivatives. Here we present a more comprehensive study on the parent peptide MP196 with regard to clinically relevant parameters. We found that MP196 acts rapidly bactericidal killing 97% of initial CFU within 10 min at two times MIC. We were unable to detect resistance in standard 24 and 48 h resistance frequency assays. However, MP196 was effective against some but not all MRSA and VISA strains. Serum binding of MP196 was intermediate and we confirmed its low toxicity against mammalian cell lines. MP196 did neither induce NFκB activation nor cause an increase in IL8 levels at 250 µg/mL, and no IgE-dependent activation of basophil granulocytes was detected at 500 µg/mL. Yet, MP196 demonstrated acute toxicity in mice upon injection into the blood stream. Phase contrast microscopy of mouse blood treated with MP196 revealed a shrinking of erythrocytes at 250 µg/mL and severe morphological changes and lysis of erythrocytes at 500 µg/mL. These data suggest that MP196 derivatization directed at further lowering hemolysis could be instrumental in overcoming acute toxicity. The assessment of hemolysis is a critical step in the evaluation of the clinical potential of promising antimicrobial peptides and should be accompanied by microscopy-based morphological analysis of blood cells.
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Papers by Cuong Vuong