RESUMO
Antibiotic resistance is an increasing challenge for the human pathogen Staphylococcus aureus. Methicillin-resistant S. aureus (MRSA) clones have spread globally, and a growing number display decreased susceptibility to vancomycin, the favoured antibiotic for treatment of MRSA infections. These vancomycin-intermediate S. aureus (VISA) or heterogeneous vancomycin-intermediate S. aureus (hVISA) strains arise from accumulation of a variety of point mutations, leading to cell wall thickening and reduced vancomycin binding to the cell wall building block, Lipid II, at the septum. They display only minor changes in vancomycin susceptibility, with varying tolerance between cells in a population, and therefore, they can be difficult to detect. In this review, we summarize current knowledge of VISA and hVISA. We discuss the role of genetic strain background or epistasis for VISA development and the possibility of strains being 'transient' VISA with gene expression changes mediated by, for example, VraTSR, GraXSR, or WalRK signal transduction systems, leading to temporary vancomycin tolerance. Additionally, we address collateral susceptibility to other antibiotics than vancomycin. Specifically, we estimate how mutations in rpoB, encoding the ß-subunit of the RNA polymerase, affect overall protein structure and compare changes with rifampicin resistance. Ultimately, such in-depth analysis of VISA and hVISA strains in terms of genetic and transcriptional changes, as well as changes in protein structures, may pave the way for improved detection and guide antibiotic therapy by revealing strains at risk of VISA development. Such tools will be valuable for keeping vancomycin an asset also in the future.
Assuntos
Antibacterianos , Resistência a Vancomicina , Vancomicina , Vancomicina/farmacologia , Antibacterianos/farmacologia , Humanos , Resistência a Vancomicina/genética , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/tratamento farmacológico , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Testes de Sensibilidade Microbiana , Staphylococcus aureus/genética , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/metabolismo , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Adaptação Fisiológica , Staphylococcus aureus Resistente à Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/metabolismo , Mutação , Transdução de SinaisRESUMO
Staphylococcus aureus is a leading cause of healthcare-associated infections globally. Vancomycin-resistant S. aureus (VRSA), those with high-level resistance [minimum inhibitory concentration (MIC) of 16-32 µg/mL vancomycin], are uncommon, whereas vancomycin-intermediate S. aureus (VISA; MIC of 4-8 µg/mL), are isolated more frequently and develop during long-term and/or repeated use of the antibiotic. VISA can be difficult to eradicate and infections may persist. Our knowledge of mechanisms that underlie the development of VISA is incomplete. We used a genomics approach to investigate the VISA phenotype in three prominent S. aureus lineages. All VISA clinical isolates tested had increased cell wall thickness compared with vancomycin-susceptible S. aureus strains. Growth rates of clonal complex (CC) 5, CC8, and CC45 clinical isolates were reduced in 2 µg/mL vancomycin compared to media alone. Culture in 2 and 4 µg/mL vancomycin sequentially for two weeks reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin in a majority of CC5, CC8, and CC45 isolates tested. We identified alleles reported previously to contribute to the VISA phenotype, but unexpectedly, these alleles were unique to each CC. A subtherapeutic concentration of vancomycin elicited changes in the VISA transcriptome-common and unique-among the three CCs tested. Multiple genes, including those encoding a glycerate kinase, an M50 family metallopeptidase, and an uncharacterized membrane protein, were upregulated among all three lineages and not reported previously as associated with VISA. Although there are lineage-specific changes in DNA sequence, our findings suggest changes in the VISA transcriptome constitute a general response to stress that confers reduced susceptibility to multiple antibiotics. IMPORTANCE: Our understanding of the mechanisms that underlie the development of vancomycin-intermediate Staphylococcus aureus (VISA) is incomplete. To provide a more comprehensive view of this process, we compared genome sequences of clonal complex (CC) 5, CC8, and CC45 VISA clinical isolates and measured changes in the transcriptomes of these isolates during culture with a subtherapeutic concentration of vancomycin. Notably, we identified differentially expressed genes that were lineage-specific or common to the lineages tested, including genes that have not been previously reported to contribute to a VISA phenotype. Changes in gene expression were accompanied by reduced growth rate, increased cell wall thickness, and reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin. Our results provide support to the idea that changes in gene expression contribute to the development of VISA among three CCs that are a prominent cause of human infections.
Assuntos
Antibacterianos , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas , Staphylococcus aureus , Resistência a Vancomicina , Vancomicina , Vancomicina/farmacologia , Antibacterianos/farmacologia , Humanos , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Infecções Estafilocócicas/microbiologia , Resistência a Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/metabolismo , Daptomicina/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismoRESUMO
The incidence of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) infection is increasing and is associated with vancomycin treatment failures. However, studies investigating the risk factors for treatment failure in hVISA infection are limited. Patients with hVISA bacteremia treated with vancomycin over 7 days between August 2008 and June 2020 were enrolled in this study. Clinical and microbiological characteristics were compared between vancomycin treatment failure and success groups to identify the risk factors for vancomycin treatment failure. Among the 180 patients with hVISA bacteremia, 102 patients treated with vancomycin over 7 days were included. Vancomycin treatment failed in 80 (78%) patients. Patients in the vancomycin treatment failure group were older (P < 0.001) and more frequently had solid cancer (P = 0.04) than those in the vancomycin treatment success group. Solid organ transplantation (SOT) was more frequent (P < 0.001) in the vancomycin treatment success group. The Charlson comorbidity index (P = 0.01) and Acute Physiology and Chronic Health Evaluation II scores (P < 0.001) were higher in the vancomycin treatment failure group. In multivariate analysis, independent risk factors for vancomycin treatment failure were old age and severity of bacteremia. SOT and vancomycin minimal inhibitory concentration (MIC) ≤ 1.0 mg/L using the broth microdilution (BMD) method were associated with successful vancomycin treatment. Old age and infection severity were independent risk factors for vancomycin treatment failure. Vancomycin MIC using the BMD method is an important risk factor for vancomycin treatment failure, and its use should be considered in hVISA bacteremia.IMPORTANCEIn this study, we assessed the clinical and microbiological characteristics of heterogeneous vancomycin-intermediated Staphylococcus aureus (hVISA) bacteremia and identified risk factors for vancomycin treatment failure. We found that advanced age and severity of infection were independent risk factors for vancomycin treatment failure. On the other hand, solid organ transplantation and a low vancomycin minimal inhibitory concentration were associated with successful vancomycin treatment. This study highlights the importance of vancomycin minimal inhibitory concentration in hVISA bacteremia.
Assuntos
Antibacterianos , Bacteriemia , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas , Staphylococcus aureus , Falha de Tratamento , Vancomicina , Humanos , Vancomicina/uso terapêutico , Vancomicina/efeitos adversos , Masculino , Bacteriemia/tratamento farmacológico , Bacteriemia/microbiologia , Feminino , Fatores de Risco , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Pessoa de Meia-Idade , Idoso , Antibacterianos/uso terapêutico , Antibacterianos/efeitos adversos , Staphylococcus aureus/efeitos dos fármacos , Estudos Retrospectivos , Adulto , Idoso de 80 Anos ou mais , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacosRESUMO
BACKGROUND: Heterogeneous vancomycin-intermediate Staphylococcus aureus is considered one of the main causes in treatment failure of vancomycin, which leads to poor clinical outcomes. Herein, we comprehensively evaluated characteristics such as global prevalence, trend, and genetic backgrounds of these strains. METHODS: In this study, we conducted a meta-analysis based on PRISMA checklist 2020. In the beginning, global databases were searched to achieve the studies related to the prevalence of hVISA in clinical isolates of methicillin-resistant Staphylococcus aureus. After retrieving the eligible English studies, the prevalence of hVISA isolates and their trend changes were assessed using event rate with 95% confidence intervals. RESULTS: In the present study, the prevalence of 114 801 MRSA isolates (of 124 studies) was 64%. According to our results, although the frequency of infection with hVISA is increasing in recent years, there is not a significant difference between Asian countries and Europe/America (6.1% vs. 6.8%). In addition, infection with hVISA bacteria was higher in bacteraemic patients than other infections (9.4% vs. 5.5%), which increases hospitalization, treatment costs, and mortality in these patients. Isolates harbouring SCCmec types II and III are most common genotypes in hVISA strains. CONCLUSIONS: The prevalence of hVISA is increasing, which will reduce the effectiveness of vancomycin treatment in the coming years. The presence of hVISA stains in blood samples was higher than the other samples, which is threatening for bacteraemic patients. The results of the current study indicate a universal program to identify and control the spread of such strains in nosocomial infections.
Assuntos
Antibacterianos , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Vancomicina , Humanos , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Antibacterianos/farmacologia , Vancomicina/farmacologia , Vancomicina/uso terapêutico , Prevalência , Staphylococcus aureus Resistente à Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Resistência a Vancomicina , Saúde Global , GenótipoRESUMO
BACKGROUND: Patients with invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA), especially those with an elevated minimal inhibitory concentration (MIC) of vancomycin (VA), are likely to have treatment failure and poor outcomes. The aim of this study was to delineate and correlate the genotypes and phenotypes of clinical VA-intermediate S. aureus (VISA) from invasive infections in Taiwan. METHODS: Between 2006 and 2010, a total of 670 non-duplicate MRSA isolates were collected from patients with invasive infections, mostly from blood, as part of a nationwide antimicrobial surveillance program named Tigecycline in vitro Surveillance in Taiwan. Among them, 10 (1.5%) VISA (VA MIC = 4 mg/L) isolates were identified. Molecular typing with staphylococcal cassette chromosome mec (SCCmec), multilocus sequence typing, staphylococcal protein A (spa), mec-associated hypervariable region (dru), accessory gene regulator (agr), and pulse-field gel electrophoresis, and phenotypic analysis including antibiotic susceptibility testing, gene encoding Panton-Valentine leukocidin (pvl), and superantigenic toxin profiles, were analyzed. RESULTS: All but one isolate was defined as molecular health-care-associated MRSA: 6 as SCCmecIII-ST239-spa t037-agrI-dru7 (1 isolate) and dru14 (5 isolates), 2 as SCCmecII-ST5-spa t586-agrII-dru4, and one as SCCmecII-ST89-spa t3520-agrIII-dru7. One isolate was defined as SCCmecIV-ST59-spa t437-agrI-dru8, which was categorized as molecular community-associated MRSA. Five pulsotypes were identified; only one had a positive D-test and 3 were insusceptible to daptomycin (MIC â§1 mg/L). Five isolates possessed sea-selk-selq, among them 4 belonged to SCCmecIII-ST239-spa t037-agrI. CONCLUSION: In this study, VISA was rarely isolated from invasive MRSA infections, and most cases harbored limited genotypes and corresponding phenotypes.
Assuntos
Antibacterianos , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Staphylococcus aureus Resistente à Vancomicina , Humanos , Antibacterianos/farmacologia , Genótipo , Resistência a Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Tipagem de Sequências Multilocus , Fenótipo , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Proteína Estafilocócica A/genética , Taiwan/epidemiologia , Vancomicina/farmacologia , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/isolamento & purificaçãoRESUMO
Staphylococcus aureus is an opportunistic pathogen that causes a wide range of infections. Due to the rapid evolution of antibiotic resistance that leads to treatment failure, it is important to understand the underlying mechanisms. Here, the cell wall structures of several laboratory vancomycin-intermediate S. aureus (VISA) strains were analyzed. Among the VISA strains were S. aureus VC40, which accumulated 79 mutations, including most importantly 2 exchanges in the histidine-kinase VraS, and developed full resistance against vancomycin (MIC, 64 µg/ml); a revertant S. aureus VC40R, which has an additional mutation in vraR (MIC, 4 µg/ml); and S. aureus VraS(VC40), in which the 2 vraS mutations were reconstituted into a susceptible background (MIC, 4 µg/ml). A ultraperformance liquid chromatography (UPLC) analysis showed that S. aureus VC40 had a significantly decreased cross-linking of the peptidoglycan. Both S. aureus VC40 and S. aureus VraS(VC40) displayed reduced autolysis and an altered autolysin profile in a zymogram. Most striking was the significant increase in d-alanine and N-acetyl-d-glucosamine (GlcNAc) substitution of the wall teichoic acids (WTAs) in S. aureus VC40. Nuclear magnetic resonance (NMR) analysis revealed that this strain had mostly ß-glycosylated WTAs in contrast to the other strains, which showed only the α-glycosylation peak. Salt stress induced the incorporation of ß-GlcNAc anomers and drastically increased the vancomycin MIC for S. aureus VC40R. In addition, ß-glycosylated WTAs decreased the binding affinity of AtlA, the major autolysin of S. aureus, to the cell wall, compared with α-glycosylated WTAs. In conclusion, there is a novel connection between wall teichoic acids, autolysis, and vancomycin susceptibility in S. aureus. IMPORTANCE Infections with methicillin-resistant Staphylococcus aureus are commonly treated with vancomycin. This antibiotic inhibits cell wall biosynthesis by binding to the cell wall building block lipid II. We set out to characterize the mechanisms leading to decreased vancomycin susceptibility in a laboratory-generated strain, S. aureus VC40. This strain has an altered cell wall architecture with a thick cell wall with low cross-linking, which provides decoy binding sites for vancomycin. The low cross-linking, necessary for this resistance mechanism, decreases the stability of the cell wall against lytic enzymes, which separate the daughter cells. Protection against these enzymes is provided by another cell wall polymer, the teichoic acids, which contain an unusually high substitution with sugars in the ß-conformation. By experimentally increasing the proportion of ß-N-acetyl-d-glucosamine in a closely related isolate through the induction of salt stress, we could show that the ß-conformation of the sugars plays a vital role in the resistance of S. aureus VC40.
Assuntos
Ácidos Teicoicos/metabolismo , Ácidos Teicoicos/farmacologia , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/metabolismo , Vancomicina/farmacologia , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Parede Celular/metabolismo , Proteínas de Ligação a DNA/genética , Glicosilação , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/metabolismo , Testes de Sensibilidade Microbiana , Mutação , Peptidoglicano/metabolismo , Infecções Estafilocócicas , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Staphylococcus aureus Resistente à Vancomicina/genéticaRESUMO
Aim: The aim of this study was to synthesize new coumarin-based compounds and evaluate their antibacterial and antitumor potential. Results: Using transition metal-catalyzed reactions, a series of 7-hydroxycoumarin derivatives were synthesized with aliphatic and aryl moiety attached directly at C-3 of the coumarin ring and through the ethynyl or 1,2,3-triazole linker. The 3-substituted coumarin derivative bearing bistrifluoromethylphenyl at the C-4 position of 1,2,3-triazole (33) showed strong and selective antiproliferative activity against cervical carcinoma cells. The 7-hydroxy-4-methylcoumarin with a phenyl ring directly attached to coumarin at C-3 (10) showed good potency against the methicillin-resistant Staphylococcus aureus and vancomycin-resistant strains. Conclusion: The most active coumarin derivatives owe their antiproliferative potential to the 3,5-ditrifluoromethylphenyl substituent (in 33) and antibacterial activity to the aromatic moiety (in 10); their structure can be optimized further for improved effect.
Assuntos
Antibacterianos/farmacologia , Cumarínicos/farmacologia , Citostáticos/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Elementos de Transição/química , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Catálise , Cumarínicos/síntese química , Cumarínicos/química , Citostáticos/síntese química , Citostáticos/química , Humanos , Testes de Sensibilidade Microbiana , Estrutura MolecularRESUMO
The emergence of bacteria resistant to conventional antibiotics is of great concern in modern medicine because it renders ineffectiveness of the current empirical antibiotic therapies. Infections caused by vancomycin-resistant Staphylococcus aureus (VRSA) and vancomycin-intermediate S. aureus (VISA) strains represent a serious threat to global health due to their considerable morbidity and mortality rates. Therefore, there is an urgent need of research and development of new antimicrobial alternatives against these bacteria. In this context, the use of antimicrobial peptides (AMPs) is considered a promising alternative therapeutic strategy to control resistant strains. Therefore, a wide number of natural, artificial, and synthetic AMPs have been evaluated against VRSA and VISA strains, with great potential for clinical application. In this regard, we aimed to present a comprehensive and systematic review of research findings on AMPs that have shown antibacterial activity against vancomycin-resistant and vancomycin-intermediate resistant strains and clinical isolates of S. aureus, discussing their classification and origin, physicochemical and structural characteristics, and possible action mechanisms. This is the first review that includes all peptides that have shown antibacterial activity against VRSA and VISA strains exclusively.
Assuntos
Proteínas Citotóxicas Formadoras de Poros/uso terapêutico , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Humanos , Proteínas Citotóxicas Formadoras de Poros/química , Proteínas Citotóxicas Formadoras de Poros/classificação , Proteínas Citotóxicas Formadoras de Poros/farmacologiaRESUMO
Over 60-year clinical use of vancomycin led to the emergence of vancomycin-resistant bacteria and threatened our health. To combat vancomycin-resistant strains, numerous vancomycin analogues were developed, such as Telavancin, Oritavancin and Dalbavancin. Extra structures embedded on C-terminus has been proved to be an effective strategy to promote antibacterial activity of vancomycin against vancomycin-resistant strains. Here, we reported a facile strategy, inspired by native chemical ligation, for vancomycin C-terminus functionalization and derivatization. The introduction of C-terminal hydrazide on vancomycin not only provided us an accessible method for C-terminus functionalization through carbonyl azide and thioester, also acted as an efficient site for vancomycin structure modifications. Based on hydrazide-vancomycin, we effectively conjugated cysteine and cysteine containing peptides onto vancomycin C-terminus, and two fluorescent FITC-vancomycin were prepared through Cys-Maleimide conjugation. Meanwhile, we introduced lipophilic structures onto vancomycin C-terminus via the hydrazide moiety. The obtained vancomycin derivatives were evaluated against both Gram-positive and negative bacteria strains.
Assuntos
Antibacterianos/farmacologia , Hidrazinas/farmacologia , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Vancomicina/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Relação Dose-Resposta a Droga , Humanos , Hidrazinas/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade , Vancomicina/síntese química , Vancomicina/químicaRESUMO
Recent genomic studies of methicillin-resistant Staphylococcus aureus (MRSA) have revealed genetic diversity in the various clonal lineages. Along with clinical concerns of MRSA infection, infection with heterogeneous vancomycin-intermediate S. aureus (hVISA) is closely associated with treatment failure. In this study, we investigated the magnitude of genetic variation and features at the genomic level of hVISA strains isolated in South Korea. Four hVISA strains were analyzed by molecular epidemiology, antimicrobial susceptibility, and whole-genome sequencing methods, and they were compared with the reference VISA and vancomycin-susceptible S. aureus strains in the same clonal lineage. The epidemiologic features of hVISA strains were closely related to the ST5 and ST239 clones. Comparative analysis of the whole genome showed genetic mutations, particularly in two-component systems (TCSs) and transcriptional regulators. Genetic mutations in walK were commonly found in both ST5- (F545L, E378K, T500K) and ST239-related (E424D, T492R) hVISA strains. hVISA strains in the ST5 clonal lineage contained mutations in TCS genes, including the walK, vraR, and agr loci, whereas ST239-related strains harbored different genetic variations in walK, lytR, and saeR. This study suggests that the diverse genetic variation of TCSs and transcriptional regulators are involved in reduced vancomycin susceptibility through different mechanisms in each clonal lineage.
Assuntos
Antibacterianos/farmacologia , Genes Bacterianos/genética , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/genética , Humanos , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , República da Coreia , Sequenciamento Completo do GenomaRESUMO
Methicillin-resistant S. aureus (MRSA) and their antimicrobial resistance pose exacerbating global health threats and endangering everyone. Thus, the prevalence, molecular characterization of virulence genes, and antimicrobial resistance patterns of strains isolated from 225 beef burger and hot dog sandwiches vended in Mansoura city, Egypt were determined. 83.1% of the sandwiches tested were contaminated with coagulase-positive S. aureus, with a mean count of 4 × 103 CFU/g. Genes encoding mecA, α-hemolysin, staphylococcal enterotoxins, and toxic shock syndrome toxin-1 were detected in 22.6%, 96.3%, 61.1%, and 0% of the strains isolated, respectively. Of the 190 coagulase-positive strains, 43 (22.6%) were confirmed as MRSA. Among them, 4 strains (2.1%) were vancomycin-resistant S. aureus (VRSA) and resistant to all antimicrobials tested. Interestingly, all isolates were resistant to at least one of the antimicrobials tested, with 75.2% being multi-drug resistant (MDR) and an average multiple antimicrobial resistance (MAR) index of 0.503. Not less important, 100%, 96.3%, 90.5%, 79.5%, 73.7%, 62.6%, and 48.9% of isolates were resistant to Kanamycin, Nalidixic acid, Cefotaxime, Sulphamethoxazole-Trimethoprim, Penicillin G, Tetracycline, and Cephalothin, respectively. The potential hazard of MDR-, MRSA-, and VRSA-contaminated sandwiches may be an indication of the presence of what is more dangerous. Hence, strict hygienic measures and good standards of food handler's personal hygiene to prevent transmission of these pathogens to consumers are imperative.
Assuntos
Fast Foods/microbiologia , Contaminação de Alimentos/análise , Produtos da Carne/microbiologia , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Vancomicina/isolamento & purificação , Animais , Antibacterianos/farmacologia , Bovinos , Qualidade de Produtos para o Consumidor , Farmacorresistência Bacteriana Múltipla , Egito , Enterotoxinas/genética , Contaminação de Alimentos/estatística & dados numéricos , Humanos , Produtos da Carne/análise , Meticilina/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Saúde Pública , Suínos , Vancomicina/farmacologia , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/genéticaRESUMO
INTRODUCTION: Heteroresistant vancomycin intermediate Staphylococcus aureus (hVISA) testing is recommended when therapeutic failure is suspected in the clinics. In our research, we aimed to investigate the prevalence of hVISA among methicilline-resistant S. aureus (MRSA) isolates in our university hospital and compared three methods for detection of hVISA. METHODOLOGY: One hundred MRSA clinical isolates were collected in our medical microbiology laboratory between 01.04.2018 and 01.10.2019. For screening of hVISA, we used two screening agar plates and used one commercial medium; brain heart infusion agar (BHI) plates containing 4 µg/mL vancomycin and 16 g/Lt casein (BHIA-VC; Satola's test), BHI agar plates containing 4 µg/mLvancomycin (BHIAV), and commercially obtained vancomycin resistant Enterococci (VRE) agar for detetection of hVISA. Colonies which could grow on plates were counted manually at 24th and 48th hours. RESULTS: Among 100 MRSA isolates, 43 (43%) were found as hVISA using Satola's test. BHIAV and VRE agar screening test results were found 70% and 4%, respectively. Finally, at the step, MIC values of 20 (47%) hVISA isolates reduced to 2 µg/mL after sub culturing for the gradient test. CONCLUSIONS: We found higher rates of hVISA comparing other studies in Turkey. Both VRE agar and BHIAV screening test failed to detect hVISA properly. Meropenem in combination with vancomycin inhibited the growth of 90% hVISA isolates in our study.
Assuntos
Antibacterianos/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Vancomicina/farmacologia , Meios de Cultura , Farmacorresistência Bacteriana , Feminino , Hospitais Universitários , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Prevalência , Turquia/epidemiologia , Resistência a Vancomicina , Staphylococcus aureus Resistente à Vancomicina/isolamento & purificaçãoRESUMO
Biofilm mediated infection caused by multi-drug resistant bacteria are difficult to treat since it protects the microorganisms by host defense system, making them resistant to antibiotics and other antimicrobial agents. Combating such type of nosocomial infection, especially in immunocompromised patients, is an urgent need and foremost challenge faced by clinicians. Therefore, antimicrobial photodynamic therapy (aPDT) has been intensely pursued as an alternative therapy for bacterial infections. aPDT leads to the generation of reactive oxygen species (ROS) that destroy bacterial cells in the presence of a photosensitizer, visible light and oxygen. Here, we elucidated a possibility of its clinical application by reducing the treatment time and exposing curcumin to 20 J/cm2 of blue laser light, which corresponds to only 52 s to counteract vancomycin resistant Staphylococcus aureus (VRSA) both in vitro and in vivo. To understand the mechanism of action, the generation of total reactive oxygen species (ROS) was quantified by 2'-7'-dichlorofluorescein diacetate (DCFH-DA) and the type of phototoxicity was confirmed by fluorescence spectroscopic analysis. The data showed more production of singlet oxygen, indicating type-II phototoxicity. Different anti-biofilm assays (crystal violet and congo red assays) and microscopic studies were performed at sub-MIC concentration of curcumin followed by treatment with laser light against preformed biofilm of VRSA. The result showed significant reduction in the preformed biofilm formation. Finally, its therapeutic potential was validated in skin abrasion wistar rat model. The result showed significant inhibition of bacterial growth. Furthermore, immunomodulatory analysis with rat serum was performed. A significant reduction in expression of proinflammatory cytokines TNF-α and IL-6 were observed. Hence, we conclude that curcumin mediated aPDT with 20 J/cm2 of blue laser treatment (for 52 s) could be used against multi-drug resistant bacterial infections and preformed biofilm formation as a potential therapeutic approach.
Assuntos
Anti-Infecciosos/administração & dosagem , Curcumina/administração & dosagem , Fotoquimioterapia/métodos , Infecções Cutâneas Estafilocócicas/tratamento farmacológico , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Administração Cutânea , Animais , Carga Bacteriana/efeitos dos fármacos , Carga Bacteriana/efeitos da radiação , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Biofilmes/efeitos da radiação , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla , Humanos , Lasers Semicondutores , Masculino , Testes de Sensibilidade Microbiana , Fotoquimioterapia/instrumentação , Ratos , Espécies Reativas de Oxigênio/metabolismo , Pele/microbiologia , Pele/patologia , Infecções Cutâneas Estafilocócicas/microbiologia , Infecções Cutâneas Estafilocócicas/patologia , Staphylococcus aureus Resistente à Vancomicina/crescimento & desenvolvimento , Staphylococcus aureus Resistente à Vancomicina/isolamento & purificaçãoRESUMO
BACKGROUND: Infections caused by drug-resistant Staphylococcus aureus, especially vancomycin-intermediate Staphylococcus aureus (VISA), leave clinicians with limited therapeutic options for treatment. Persister cells is a leading cause of recalcitrant infection and antibiotic treatment failure, and there is no drug in clinical use that specifically targets persister cells currently. Here, we report a promising combination therapy of sodium new houttuyfonate (SNH) and berberine chloride (BBR) which is able to eradicate both growing and persistent drug-resistant Staphylococcus aureus. RESULTS: The susceptibility test showed SNH exhibited anti-MRSA activity with MIC90 at 64 µg/mL, while BBR showed weak anti-MRSA activity with MIC90 at 512 µg/mL. MICs of BBR in combination with 1/2 MIC SNH decreased by 4 to 64 folds compared with MICs of BBR alone. The results of time-killing assays revealed that the combined use of sub-MIC SNH and BBR offered an in vitro synergistic action against growing MRSA (including pathogenic MRSA) and VISA strains. More importantly, the combination of SNH and BBR was able to eradicate VISA Mu50 and pathogenic MRSA persister cells. The synergistic effect is likely related to the interruption of the cell membrane caused by SNH, which is confirmed by scanning electron microscope and membrane potential and permeability analysis. CONCLUSIONS: Our study provide a promising clinical curative strategy for combating drug-resistant S. aureus infections, especially for recalcitrant infections caused by persister cells.
Assuntos
Antibacterianos/farmacologia , Berberina/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Ácidos Sulfônicos/farmacologia , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Combinação de Medicamentos , Sinergismo Farmacológico , Humanos , Resistência a Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/microbiologia , Resistência a Vancomicina/efeitos dos fármacosRESUMO
Nanozymes that mimic peroxidase (POD) activity can convert H2O2 into bactericidal free radicals, which is referred to as chemodynamic therapy (CDT). High glutathione (GSH) levels in the infectious tissue severely limit the performance of CDT. Herein, we report a near-infrared-controlled antibacterial nanoplatform that is based on encapsulating tungsten sulfide quantum dots (WS2QDs) and the antibiotic vancomycin in a thermal-sensitive liposome. The system exploits the photothermal sensitivity of the WS2QDs to achieve selective liposome rupture for the targeted drug delivery. We determined that WS2QDs show a strong POD-like activity under physiological conditions and the oxidase-like activity, which can oxidate GSH to further improve the CDT efficacy. Moreover, we found that increased temperature promotes multiple enzyme-mimicking activities of WS2QDs. This platform exerts antibacterial effects against Gram-positive Mu50 (a vancomycin-intermediate Staphylococcus aureus reference strain) and Gram-negative Escherichia coli and disrupts biofilms for improved penetration of therapeutic agents inside biofilms. In vivo studies with mice bearing Mu50-caused skin abscess revealed that this platform confers potent antibacterial activity without obvious toxicity. Accordingly, our work illustrates that the photothermal and nanozyme properties of WS2QDs can be deployed alongside a conventional therapeutic to achieve synergistic chemodynamic/photothermal/pharmaco therapy for powerful antibacterial effects.
Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Nanopartículas/química , Temperatura , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Vancomicina/farmacologia , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Raios Infravermelhos , Lipossomos/química , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Processos Fotoquímicos , Pontos Quânticos/química , Sulfetos/química , Propriedades de Superfície , Compostos de Tungstênio/química , Vancomicina/químicaRESUMO
BACKGROUND: Methicillin-resistant and vancomycin-resistant Staphylococcus aureus are pathogens causing severe infectious diseases that pose real public health threats problems worldwide. In S. aureus, the most efficient multidrug-resistant system is the NorA efflux pump. For this reason, it is critical to identify efflux pump inhibitors. OBJECTIVE: In this paper, we present an update of the new natural and synthetic compounds that act as modulators of antibiotic resistance through the inhibition of the S. aureus NorA efflux pump. RESULTS: Several classes of compounds capable of restoring the antibiotic activity have been identified against resistant-S. aureus strains, acting as NorA efflux pump inhibitors. The most promising classes of compounds were quinolines, indoles, pyridines, phenols, and sulfur-containing heterocycles. However, the substantial degree structural diversity of these compounds makes it difficult to establish good structure- activity correlations that allow the design of compounds with more promising activities and properties. CONCLUSION: Despite substantial efforts put forth in the search for new antibiotic adjuvants that act as efflux pump inhibitors, and despite several promising results, there are currently no efflux pump inhibitors authorized for human or veterinary use, or in clinical trials. Unfortunately, it appears that infection control strategies have remained the same since the discovery of penicillin, and that most efforts remain focused on discovering new classes of antibiotics, rather than trying to prolong the life of available antibiotics, and simultaneously fighting mechanisms of bacterial resistance.
Assuntos
Antibacterianos/química , Proteínas de Bactérias/antagonistas & inibidores , Proteínas Associadas à Resistência a Múltiplos Medicamentos/antagonistas & inibidores , Infecções Estafilocócicas/tratamento farmacológico , Antibacterianos/farmacologia , Descoberta de Drogas , Farmacorresistência Bacteriana , Humanos , Indóis/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Fenóis/química , Conformação Proteica , Piridinas/química , Quinolinas/química , Relação Estrutura-Atividade , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacosRESUMO
The number of cases of failure in the treatment of infections associated with resistant bacteria is on the rise, due to the decreasing efficacy of current antibiotics. Notably, 7α-Acetoxy-6ß-hydroxyroyleanone (AHR), a diterpene isolated from different Plectranthus species, showed antibacterial activity, namely against Methicillin-resistant Staphylococcus aureus (MRSA) strains. The high antibacterial activity and low cytotoxicity render this natural compound an interesting alternative against resistant bacteria. The aim of this study is to understand the mechanism of action of AHR on MRSA, using the MRSA/Vancomycin-intermediate S. aureus (VISA) strain CIP 106760, and to study the AHR effect on lipid bilayers and on the cell wall. Although AHR interacted with lipid bilayers, it did not have a significant effect on membrane passive permeability. Alternatively, bacteria treated with this royleanone displayed cell wall disruption, without revealing cell lysis. In conclusion, the results gathered so far point to a yet undescribed mode of action that needs further investigation.
Assuntos
Diterpenos/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Membrana Externa Bacteriana , Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacosRESUMO
The increasing spread of antibiotic resistant bacteria is a major human health concern. The challenging development of new effective antibiotics has led to focus on seeking synergistic antibiotic combinations. Vancomycin (VAN) is a glycopeptide antibiotic used to treat Staphylococcus aureus and enterococci infections. It is targeting D-Alanyl-D-Alanine dimers during peptidoglycan biosynthesis. D-cycloserine (DCS) is a D-Alanine analogue that targets peptidoglycan biosynthesis by inhibiting D-Alanine:D-Alanine ligase (Ddl). The VAN-DCS combination was found to be synergistic in VAN resistant S. aureus strains lacking van genes cluster. We hypothesize that this combination leads to opposite effects in S. aureus and enterococci strains harboring van genes cluster where VAN resistance is conferred by the synthesis of modified peptidoglycan precursors ending in D-Alanyl-D-Lactate. The calculated Fractional Inhibitory Concentration of VAN-DCS combination in a van- vancomycin-intermediate, VanA type, and VanB type strains were 0.5, 5 and 3, respectively. As a result, VAN-DCS combination leads to synergism in van-lacking strains, and to antagonism in strains harboring van genes cluster. The VAN-DCS antagonism is due to a mechanism that we named van-mediated Ddl inhibition bypass. Our results show that antibiotic combinations can lead to opposite effects depending on the genetic backgrounds.
Assuntos
Enterococcus/efeitos dos fármacos , Resistência a Vancomicina/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacos , Vancomicina/farmacologia , Ciclosserina/farmacologia , Combinação de Medicamentos , Sinergismo Farmacológico , Enterococcus/genética , Resistência a Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/genéticaRESUMO
A new series of N-substituted pyrazoline derivatives 6a-g, 7a-g, 8a-g, and 9a-g was synthetized by reaction of hydrazine derivatives and chalcone-thiazole hybrids bearing nitrogen mustard 5a-g. The chalcones 5a-g were obtained by Claisen-Schmidt condensation of thiazole-2-nitrogen mustard 3 and selected acetophenones 4a-g. These new compounds 6/7/8/9a-g were screened for their antifungal activity against Cryptococcus neoformans, with IC50 values of 3.9-7.8 µg/ml for the N-3,5-dichlorophenyl pyrazolines 9e-g. Interestingly, those compounds show low cytotoxic effects toward erythrocytes (RBC). In addition, N-acetyl (6a,b) and N-formyl pyrazolines (7a, 7b, 7c, and 7g) showed inhibitory activity against methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus, and vancomycin-intermediate S. aureus, with the most important minimum inhibitory concentration values ranging from 31.25 to 125 µg/ml. Regarding the antiprotozoal activity, thiazolyl-pyrazolines 9g, 8f, and 7c display high activity against Plasmodium falciparum, Leishmania (V) panamensis, and Trypanosoma cruzi, with EC50 values of 11.80, 6.46, and 4.98 µM, respectively, and with 7c being approximately 2.6-fold more potent than benznidazole with a selectivity index of 1.61 on U-937 human cells, showing promising potential as a novel antitrypanosomal agent.
Assuntos
Antibacterianos/farmacologia , Antiprotozoários/farmacologia , Mecloretamina/farmacologia , Pirazóis/farmacologia , Tiazóis/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Antiprotozoários/síntese química , Antiprotozoários/química , Relação Dose-Resposta a Droga , Leishmania/efeitos dos fármacos , Mecloretamina/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Testes de Sensibilidade Parasitária , Plasmodium falciparum/efeitos dos fármacos , Pirazóis/química , Relação Estrutura-Atividade , Tiazóis/química , Trypanosoma cruzi/efeitos dos fármacos , Staphylococcus aureus Resistente à Vancomicina/efeitos dos fármacosRESUMO
BACKGROUND: The potential of transmitting multidrug resistant Staphylococcus aureus from asymptomatic individuals to healthy individuals could constitute a great challenge to antimicrobial therapy. METHODS: The antibiograms of the S. aureus from asymptomatic individuals were determined by disk diffusion and agar dilution assay techniques with different antibiotics and vancomycin. RESULTS: Of the 152 S. aureus isolated, (59)38.8% isolates were multi-drug resistant strains. Streptomycin was the most effective and inhibited (135)88.82% of the isolates while ceftazidime inhibited (24)15.8% of the isolates. While (82)54.0% of the isolates inhibited by cefuroxime had resistant colonies within their inhibition zones (Rc) and ofloxacin inhibited (100)65.8% of the isolates without having resistant colonies within the inhibition zones, ceftazidime inhibited (7)4.6% of the isolates with resistant colonies within the inhibition zones. Subjecting the isolates to vancomycin showed that (27)17.8% were resistant to 2 µg/ml, (43)28.3% were resistant to 4 µg/ml and (27)17.8% of the isolates were simultaneously resistant to both concentrations of vancomycin. Although (100)65.8% of the isolates had MARindex ≥0.2, (52)34.2% of the isolates had MARindex ≤ 0.2 and (65)428% of the isolates were considered multidrug resistant strains. CONCLUSION: The isolation of multi-drug and vancomycin intermediate resistant strains of S. aureus in high percentage, in this study, presents a great threat to clinicians and general populace. The vancomycin intermediate resistant S. aureus (VISA) in asymptomatic individuals could be a critical concern to the therapeutic dilemma to be added to the presence of multi-drug resistance. A more sustainable therapy must be in place to prevent its dissemination or the outbreak of its infection.