scholarly journals PROPAGATION OF ANTIMICROBIAL RESISTANT Salmonella spp. IN BIVALVE MOLLUSKS FROM ESTUARY AREAS OF BAHIA, BRAZIL

2016 ◽  
Vol 29 (2) ◽  
pp. 450-457 ◽  
Author(s):  
CARLA SILVA DA SILVEIRA ◽  
OSCARINA VIANA DE SOUSA ◽  
NORMA SUELY EVANGELISTA-BARRETO
Keyword(s):  
Nalidixic Acid ◽  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Resistance Index ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Bivalve Mollusks ◽  
Salmonella Spp ◽  
Development Of Resistance

ABSTRACT: In recent years, the emergence of resistant pathogens has complicated the treatment of bacterial infections in livestock production as well as in the medical field, due to the development of resistance mechanisms by microorganisms. The objective of this study was to delineate the antimicrobial resistance profile of Salmonella spp. strains isolated from bivalve mollusks (oysters and mussels) and from estuarine environment water of two regions of Bahia, Brazil. Twenty-seven strains, 12 isolated from bivalve mollusks and 15 from estuarine water, were tested. Eight antimicrobial agents (phenicol, beta-lactams, tetracyclines, quinolones and fluoroquinolones classes) were used for a susceptibility test, Minimum Inhibitory Concentration (MIC) and extended-spectrum beta-lactamases (ESBLs) production. Isolates showed high susceptibility to the classes of antimicrobial agents tested, with resistance only to nalidixic acid (27%), ampicillin (25%) and tetracycline (25%). Bacterial resistance was of chromosomal origin and the multidrug resistance index (MAR) among isolates of shellfish (mussels in natura) was 0.25. The MIC was found to be 100 µg/mL, 500 µg/mL and 350 µg/mL to nalidixic acid, ampicillin and tetracycline, respectively. None of the isolates presented ESBLs production. The presence of multidrug-resistant and high MIC Salmonella spp. is being conveyed in extraction areas of bivalve mollusks in the State of Bahia, Brazil.

scholarly journals Silver (I) N-Heterocyclic Carbene Complexes: A Winning and Broad Spectrum of Antimicrobial Properties

2021 ◽  
Vol 22 (5) ◽  
pp. 2497
Author(s):  
Filippo Prencipe ◽  
Anna Zanfardino ◽  
Michela Di Napoli ◽  
Filomena Rossi ◽  
Stefano D’Errico ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Antimicrobial Properties ◽  
Resistance Mechanisms ◽  
Heterocyclic Carbenes ◽  
Significant Activity ◽  
Bacterial Strains ◽  
Development Of Resistance ◽  
Starting Point ◽  
Catalytic Chemistry

The evolution of antibacterial resistance has arisen as the main downside in fighting bacterial infections pushing researchers to develop novel, more potent and multimodal alternative drugs.Silver and its complexes have long been used as antimicrobial agents in medicine due to the lack of silver resistance and the effectiveness at low concentration as well as to their low toxicities compared to the most commonly used antibiotics. N-Heterocyclic Carbenes (NHCs) have been extensively employed to coordinate transition metals mainly for catalytic chemistry. However, more recently, NHC ligands have been applied as carrier molecules for metals in anticancer applications. In the present study we selected from literature two NHC-carbene based on acridinescaffoldand detailed nonclassicalpyrazole derived mono NHC-Ag neutral and bis NHC-Ag cationic complexes. Their inhibitor effect on bacterial strains Gram-negative and positivewas evaluated. Imidazolium NHC silver complex containing the acridine chromophore showed effectiveness at extremely low MIC values. Although pyrazole NHC silver complexes are less active than the acridine NHC-silver, they represent the first example of this class of compounds with antimicrobial properties. Moreover all complexesare not toxic and they show not significant activity againstmammalian cells (Hek lines) after 4 and 24 h. Based on our experimental evidence, we are confident that this promising class of complexes could represent a valuable starting point for developing candidates for the treatment of bacterial infections, delivering great effectiveness and avoiding the development of resistance mechanisms.

Antibiotic Cycling and Marketing Into the 21st Century: A Perspective From the Pharmaceutical Industry

2000 ◽  
Vol 21 (S1) ◽  
pp. S32-S35 ◽  
Author(s):  
Bruce S. Lavin
Keyword(s):  
Antimicrobial Resistance ◽  
Pharmaceutical Industry ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Resistance Mechanisms ◽  
Medical Community ◽  
Resistant Bacteria ◽  
Environmental Pressures ◽  
Development Of Resistance ◽  
Antibiotic Cycling

AbstractBefore the development of the first antimicrobial agents, bacteria already had demonstrated an ability to adapt to stress in the environment, resulting in the development of resistance that often makes the prevailing antibiotic treatment ineffective. The response to antimicrobial resistance in the medical community has been to use new or alternative antibiotics not previously used against the resistant bacteria. The pharmaceutical industry has responded to the resistance problem by producing newer antibiotics, either as modifications of currently existing compounds or as combinations of compounds that may inhibit or bypass the bacterial resistance mechanisms. The development of new antibiotics is a lengthy and costly process. To be successful, the pharmaceutical industry must anticipate the changing needs of the medical community, as well as the dynamic process of antimicrobial resistance. The marketing of new antimicrobial agents must be adaptable to the potential environmental pressures that induce bacterial resistance in order to ensure the longevity of the agents.

scholarly journals Multidrug-Resistant Acinetobacter baumannii Genetic Characterization and Spread in Lithuania in 2014, 2016, and 2018

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 151
Author(s):  
Tatjana Kirtikliene ◽  
Aistė Mierauskaitė ◽  
Ilona Razmienė ◽  
Nomeda Kuisiene
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Variable Number Tandem Repeat ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Essential Information ◽  
Acinetobacter Spp

Bacterial resistance to antimicrobial agents plays an important role in the treatment of bacterial infections in healthcare institutions. The spread of multidrug-resistant bacteria can occur during inter- and intra-hospital transmissions among patients and hospital personnel. For this reason, more studies must be conducted to understand how resistance occurs in bacteria and how it moves between hospitals by comparing data from different years and looking out for any patterns that might emerge. Multidrug-resistant (MDR) Acinetobacter spp. was studied at 14 healthcare institutions in Lithuania during 2014, 2016, and 2018 using samples from human bloodstream infections. In total, 194 isolates were collected and identified using MALDI-TOF and VITEK2 analyzers as Acinetobacter baumannii group bacteria. After that, the isolates were analyzed for the presence of different resistance genes (20 genes were analyzed) and characterized by using the Rep-PCR and MLVA (multiple-locus variable-number tandem repeat analysis) genotyping methods. The results of the study showed the relatedness of the different Acinetobacter spp. isolates and a possible circulation of resistance genes or profiles during the different years of the study. This study provides essential information, such as variability and diversity of resistance genes, genetic profiling, and clustering of isolates, to better understand the antimicrobial resistance patterns of Acinetobacter spp. These results can be used to strengthen the control of multidrug-resistant infections in healthcare institutions and to prevent potential outbreaks of this pathogen in the future.

Synergism between Host Defence Peptides and Antibiotics Against Bacterial Infections

2020 ◽  
Vol 20 (14) ◽  
pp. 1238-1263 ◽  
Author(s):  
Jiarui Li ◽  
Pablo Fernández-Millán ◽  
Ester Boix
Keyword(s):  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Resistance Mechanisms ◽  
Adjuvant Activity ◽  
Biofilm Growth ◽  
Intracellular Target ◽  
Conventional Antibiotics ◽  
Available Information ◽  
Toxic Concentrations

Background: Antimicrobial resistance (AMR) to conventional antibiotics is becoming one of the main global health threats and novel alternative strategies are urging. Antimicrobial peptides (AMPs), once forgotten, are coming back into the scene as promising tools to overcome bacterial resistance. Recent findings have attracted attention to the potentiality of AMPs to work as antibiotic adjuvants. Methods: In this review, we have tried to collect the currently available information on the mechanism of action of AMPs in synergy with other antimicrobial agents. In particular, we have focused on the mechanisms of action that mediate the inhibition of the emergence of bacterial resistance by AMPs. Results and Conclusion: We find in the literature many examples where AMPs can significantly reduce the antibiotic effective concentration. Mainly, the peptides work at the bacterial cell wall and thereby facilitate the drug access to its intracellular target. Complementarily, AMPs can also contribute to permeate the exopolysaccharide layer of biofilm communities, or even prevent bacterial adhesion and biofilm growth. Secondly, we find other peptides that can directly block the emergence of bacterial resistance mechanisms or interfere with the community quorum-sensing systems. Interestingly, the effective peptide concentrations for adjuvant activity and inhibition of bacterial resistance are much lower than the required for direct antimicrobial action. Finally, many AMPs expressed by innate immune cells are endowed with immunomodulatory properties and can participate in the host response against infection. Recent studies in animal models confirm that AMPs work as adjuvants at non-toxic concentrations and can be safely administrated for novel combined chemotherapies.

scholarly journals Phage Resistance Mechanisms Increase Colistin Sensitivity in Acinetobacter baumannii

2021 ◽  
Author(s):  
Xiaoqing Wang ◽  
Belinda Loh ◽  
Yunsong Yu ◽  
Xiaoting Hua ◽  
Sebastian Leptihn
Keyword(s):  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Phage Therapy ◽  
Resistance Mechanism ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Phage Resistance ◽  
Colistin Resistance ◽  
Increased Sensitivity

Few emergency-use antibiotics remain for the treatment of multidrug-resistant bacterial infections. Infections with resistant bacteria are becoming increasingly common. Phage therapy has reemerged as a promising strategy to treat such infections, as microbial viruses are not affected by bacterial resistance to antimicrobial compounds. However, phage therapy is impeded by rapid emergence of phage-resistant bacteria during therapy. In this work, we studied phage-resistance of colistin sensitive and resistant A. baumannii strains. Using whole genome sequencing, we determined that phage resistant strains displayed mutations in genes that alter the architecture of the bacterial envelope. In contrast to previous studies where phage-escape mutants showed decreased binding of phages to the bacterial envelope, we obtained several not uninfectable isolates that allowed similar phage adsorption compared to the susceptible strain. When phage-resistant bacteria emerged in the absence of antibiotics, we observed that the colistin resistance levels often decreased, while the antibiotic resistance mechanism per se remained unaltered. In particular the two mutated genes that conveyed phage resistance, a putative amylovoran- biosynthesis and a lipo-oligosaccharide (LOS) biosynthesis gene, impact colistin resistance as the mutations increased sensitivity to the antibiotic.

Bacterial Resistance: Antibiotics of Last Generation used in Clinical Practice and the Arise of Natural Products as New Therapeutic Alternatives

2020 ◽  
Vol 26 (8) ◽  
pp. 815-837 ◽  
Author(s):  
Rúbia C.G. Corrêa ◽  
Sandrina A. Heleno ◽  
Maria J. Alves ◽  
Isabel C.F.R. Ferreira
Keyword(s):  
Natural Products ◽  
Natural Resources ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Resistance Mechanisms ◽  
Critical Discussion ◽  
Public Health Issue ◽  
Resistant Bacteria ◽  
Natural Agents ◽  
Development Of Resistance

Bacterial resistance to therapeutical drugs has been a serious issue over the last decades. In fact, the quick development of resistance mechanisms by the microorganisms has been fatal for millions of people around the world, turning into a public health issue. The major cause of the resistance mechanisms is the overuse of antimicrobials. European countries try to implement mechanisms to overcome antimicrobial resistance in the community through the rational use of antimicrobials. The scientific community has been exhaustively dedicated to the discovering of new, safer and efficient drugs, being the exploitation of natural resources, mainly plants and fungi, considered as a hot topic in the field of antimicrobial agents. Innumerous reports have already shown the promising capacity of natural products or molecules extracted from these natural resources, to act as bacteriostatic and bactericidal agents. More importantly, these natural agents present significantly lower harmful effects. Bearing that in mind, this review aims at giving a contribution to the knowledge about the synthetic antibiotics of the last generation. Moreover, it is intended to provide information about the last advances regarding the discovery of new antimicrobial agents. Thus, a compilation of the chemical characteristics, efficiency, harmful outcomes and resistance mechanisms developed by the microorganisms can be consulted in the following sections together with a critical discussion, in line with the recent approaches. Furthermore, modern strategies for the prospection of novel anti-infective compounds for tackling resistant bacteria have been considered as also a current synopsis of plants and mushrooms with relevant antimicrobial potentials.

scholarly journals Synergistic Activity of Nitroimidazole-Oxazolidinone Conjugates against Anaerobic Bacteria

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2431
Author(s):  
Zhijun Zhuang ◽  
Dawei Wan ◽  
Jun Ding ◽  
Shijie He ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Anaerobic Bacteria ◽  
Multidrug Resistant ◽  
Combination Regimen ◽  
Synergistic Activity ◽  
Conjugate Series ◽  
Development Of Resistance ◽  
The Us ◽  
Serious Bacterial Infections

The introductions of the bicyclic 4-nitroimidazole and the oxazolidinone classes of antimicrobial agents represented the most significant advancements in the infectious disease area during the past two decades. Pretomanid, a bicyclic 4-nitroimidazole, and linezolid, an oxazolidinone, are also part of a combination regimen approved recently by the US Food and Drug Administration for the treatment of pulmonary, extensively drug resistant (XDR), treatment-intolerant or nonresponsive multidrug-resistant (MDR) Mycobacterium tuberculosis (TB). To identify new antimicrobial agents with reduced propensity for the development of resistance, a series of dual-acting nitroimidazole-oxazolidinone conjugates were designed, synthesized and evaluated for their antimicrobial activity. Compounds in this conjugate series have shown synergistic activity against a panel of anaerobic bacteria, including those responsible for serious bacterial infections.

scholarly journals Bacterial Resistance to Antimicrobial Agents

Antibiotics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 593
Author(s):  
Manuel F. Varela ◽  
Jerusha Stephen ◽  
Manjusha Lekshmi ◽  
Manisha Ojha ◽  
Nicholas Wenzel ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Drug Targets ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Health Sector ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Cellular Mechanisms ◽  
Causative Agents

Bacterial pathogens as causative agents of infection constitute an alarming concern in the public health sector. In particular, bacteria with resistance to multiple antimicrobial agents can confound chemotherapeutic efficacy towards infectious diseases. Multidrug-resistant bacteria harbor various molecular and cellular mechanisms for antimicrobial resistance. These antimicrobial resistance mechanisms include active antimicrobial efflux, reduced drug entry into cells of pathogens, enzymatic metabolism of antimicrobial agents to inactive products, biofilm formation, altered drug targets, and protection of antimicrobial targets. These microbial systems represent suitable focuses for investigation to establish the means for their circumvention and to reestablish therapeutic effectiveness. This review briefly summarizes the various antimicrobial resistance mechanisms that are harbored within infectious bacteria.

scholarly journals Tigecycline: a review of the literature

2006 ◽  
Vol 7 (4) ◽  
pp. 211-222
Author(s):  
Mario Venditti ◽  
Maria Elena Pompeo ◽  
Flavia Fabi
Keyword(s):  
Antimicrobial Agent ◽  
Broad Spectrum ◽  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Antibiotic Administration ◽  
Spectrum Activity

Tigecycline is a new first-in-class glycylcycline antimicrobial agent with expanded broad-spectrum activity. It was developed to overcome the two key resistance mechanisms, efflux pumps and ribosomal protection, that limit the use of tetracycline. The spectrum of activity extends to clinically relevant susceptible and multidrug resistant bacteria, as methicillin resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, vancomycin resistant Enterococci, Acinetobacter spp, Acinetobacter baumannii and Enterobacteriaceae, including extended-spectrum β-lactamase-producing strains (ESBLs). Tigecycline has been introduced into clinical practice as part of the effort to combat the growing problem of bacterial resistance to anti-infective therapy: tigecycline could replace some broad-spectrum agents for approved indications reducing the selective pressure provided by antibiotic administration. The expanded in vitro activity against a broad range of bacteria, including resistant pathogens, of tigecycline suggest that this novel antimicrobial agent should offer clinicians an option for the treatment of patients with serious bacterial infections.

Development of Peptides that Inhibit Aminoglycoside-Modifying Enzymes and β-Lactamases for Control of Resistant Bacteria

2020 ◽  
Vol 21 (10) ◽  
pp. 1011-1026
Author(s):  
Bruna O. Costa ◽  
Marlon H. Cardoso ◽  
Octávio L. Franco
Keyword(s):  
Drug Target ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Treatment Strategies ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Specific Chemical ◽  
Target Interaction ◽  
Multiresistant Bacteria ◽  
Acute Bacterial Infections

: Aminoglycosides and β-lactams are the most commonly used antimicrobial agents in clinical practice. This occurs because they are capable of acting in the treatment of acute bacterial infections. However, the effectiveness of antibiotics has been constantly threatened due to bacterial pathogens producing resistance enzymes. Among them, the aminoglycoside-modifying enzymes (AMEs) and β-lactamase enzymes are the most frequently reported resistance mechanisms. AMEs can inactivate aminoglycosides by adding specific chemical molecules in the compound, whereas β-lactamases hydrolyze the β-lactams ring, preventing drug-target interaction. Thus, these enzymes provide a scenario of multidrug-resistance and a significant threat to public health at a global level. In response to this challenge, in recent decades, several studies have focused on the development of inhibitors that can restore aminoglycosides and β-lactams activity. In this context, peptides appear as a promising approach in the field of inhibitors for future antibacterial therapies, as multiresistant bacteria may be susceptible to these molecules. Therefore, this review focused on the most recent findings related to peptide-based inhibitors that act on AMEs and β-lactamases, and how these molecules could be used for future treatment strategies.

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