antibiotic resistance and biofilm formation

A previously unreported bis -indolyl benzenoid, candidusin D ( 2e ) and a new hydroxypyrrolidine alkaloid, preussin C ( 5b ) were isolated together with fourteen previously described compounds: palmitic acid, clionasterol, ergosterol 5,8-endoperoxides, chrysophanic acid ( 1a ), emodin ( 1b ), six bis -indolyl benzenoids including asterriquinol D dimethyl ether ( 2a ), petromurin C ( 2b ), kumbicin B ( 2c ), kumbicin A ( 2d ), 2″-oxoasterriquinol D methyl ether ( 3 ), kumbicin D ( 4 ), the hydroxypyrrolidine alkaloid preussin ( 5a ), (3 S , 6 S )-3,6-dibenzylpiperazine-2,5-dione ( 6 ) and 4-(acetylamino) benzoic acid ( 7 ), from the cultures of the marine sponge-associated fungus Aspergillus candidus KUFA 0062...

There is growing awareness of the antibiotic-resistance crisis and its implications for public health among clinicians, researchers, politicians, and the public. We studied bacterial antibiotic resistance transition and the role of biofilms in a drinking water distribution system (DWDS). We tracked several different antibiotic resistant bacteria (ARB) with resistance to tetracycline, sulfamethoxazole, clindamycin, and norfloxacin for one year in a DWDS. The results indicated that the amount of ARB increased in tap water, presumably due to biofilm detachment...

The current worldwide emergence of resistance to antibiotics in bacteria constitutes an important growing public health threat. The mechanisms of the emergence and dissemination of resistance remain to be elucidated. Adaptation laboratory evolution provide an approach to investigate the acquisition of de novo mutations that confers drug resistance. In our study, 3 Enterococcus faecalis clinical isolates and E. faecalis ATCC29212 were evolved resistant to 8 kinds of antimicrobials spanning five chemical classes, including ciprofloxacin, levofloxacin, gatifloxacin, penicillin, imipenem, vancomycin, chloramphenicol and gentamicin...

Greasy pig disease or exudative epidermitis, a generalized or localized skin disease affecting piglets, is mainly caused by Staphylococcus hyicus, although other staphylococcal species such as Staphylococcus aureus may also induce disease. Piglets with skin lesions can be treated systemically with antibiotics. However, antimicrobial resistance to β-lactam antibiotics are now frequently observed in S. hyicus and S. aureus isolates. In this study, the antibacterial activity of plant essential oils as well as their ability to potentiate the effect of several antimicrobial compounds against S...

The draft genome sequences of four Salmonella enterica serovar Enteritidis and Kentucky isolates were evaluated for biofilm formation and antibiotic resistance. The Salmonella serovar Kentucky strains CFS84 and CFS85 and Salmonella serovar Enteritidis strains CFS86 and CFS87 were isolated from retail poultry sources in Arkansas.

Skin symbiotic bacteria on amphibians can play a role in protecting their host against pathogens. Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis , Bd, has caused dramatic population declines and extinctions of amphibians worldwide. Anti-Bd bacteria from amphibian skin have been cultured, and skin bacterial communities have been described through 16S rRNA gene amplicon sequencing. Here, we present a shotgun metagenomic analysis of skin bacterial communities from a Neotropical frog, Craugastor fitzingeri ...

OBJECTIVE: Pseudomonas aeruginosa, an opportunistic pathogen, can cause serious health problems and produces several virulence factors. The most important of these factors is biofilm. Many studies suggest administration of new generation of antibiotics, as P. aeruginosa biofilm has developed high resistance to antimicrobial drugs. Emergence of multidrug resistant (MDR) strains has resulted in screening biofilm inhibitors from natural products or modified from natural compounds. To test this hypothesis, we evaluated the inhibitory effects (antibacterial and antibiofilm) of Juglans regia L...

Streptococcus pyogenes, a major human pathogen, causes a wide variety of invasive systemic infections such as acute pharyngitis, skin and soft-tissue infections, especially necrotizing fasciitis. This Gram-positive bacterium has an ability to form mature biofilm and this sessile lifestyle plays an important role in S. pyogenes pathogenicity. The virulence of these bacteria is further strengthened by its ability to communicate within the micro-colonies through quorum sensing. Most treatments are now aimed at either elimination of this bacterium or suppression of its virulence...

Human infection with pathogenic vibrios is associated with contaminated seafood consumption. In the present study, we examined 225 crustaceans collected from retail markets in Egypt. Stool samples from gastroenteritis patients were also examined. Bacteriological and molecular examinations revealed 34 (15.1%) V. parahaemolyticus and 2 (0.9%) V. cholerae from crustaceans, while V. parahaemolyticus isolates were identified in 3 (3%) of the human samples. The virulence-associated genes tdh and/or trh were detected in 5...

AIM: In this study, the effect of N-acetylcysteine (NAC) alone and in combination with linezolid (LIN) and daptomycin (DAPT) was examined on methicillin-sensitive Staphylococcus aureus (MSSA) biofilm formation. MATERIAL AND METHODS: Twelve groups (each containing six molds) of standard ventriculoperitoneal shunts were infected with MSSA. By using microbiological and electron microscopic evaluation methods, NAC was evaluated, alone and in combination with DAPT and LIN, in terms of preventing and eliminating biofilm capacity...

OBJECTIVES: Antibiotic resistance among the Uropathogenic Escherichia coli (UPEC) is increasing. The aim of this study was to evaluate antimicrobial resistance in the UPEC isolates and their correlations with virulence factors. METHODS: A total of 120 E. coli isolates were collected from the patients with urinary tract infections in Tehran, Iran. Biofilm formation and antimicrobial susceptibilities were determined by phenotypic tests. Combination disk diffusion and modified Hodge tests (MHT) were performed for the phenotypic detection of ESBL and carbapenemase, respectively...

The increase of microbial resistance generates the search for new substances with antimicrobial potential. The essential oil of Cymbopogon flexuosus (Lemongrass) stands out in the literature for its antimicrobial, insecticide and antioxidant properties, but it has high volatilization and low stability, and the nanoencapsulation of this oil could be an alternative to overcome these limitations. Thus, the objective of this study was to develop, for the first time, nanoemulsions containing the essential oil of C...

Biofilms are communities of bacterial cells that serve to protect them from external adverse influences and enhance bacterial resistance to antibiotics and sanitizers. Here, we studied the regulatory effects of glucose and sodium chloride on biofilm formation in Salmonella serovar Dublin (S. Dublin). To analyze expression levels of the quorum sensing gene luxS, we created a luxS knockout mutant. Also, antimicrobial resistance, hydrophobicity and autoinducer-2 (AI-2) activity of both the wild-type (WT) and the mutant strain were investigated...

Bacterial infections are a serious issue for many implanted medical devices. Infections occur when bacteria colonize the surface of an implant and form a biofilm, a barrier which protects the bacterial colony from antibiotic treatments. Further, the anti-bacterial treatments must also be tailored to the specific bacteria that is causing the infection. The inherent protection of bacteria in the biofilm, differences in bacteria species (gram-positive vs. gram-negative), and the rise of antibiotic-resistant strains of bacteria makes device-acquired infections difficult to treat...

Burkholderia pseudomallei is the causative agent of melioidosis and regarded as a bioterrorism threat. It can adapt to the nutrient-limited environment as the bacteria can survive in triple distilled water for 16 years. Moreover, B. pseudomallei exhibits intrinsic resistance to diverse groups of antibiotics in particular while growing in biofilms. Recently, nutrient-limited condition influenced both biofilm formation and ceftazidime (CAZ) tolerance of B. pseudomallei were found. However, there is no information about how nutrient-limitation together with antibiotics used in melioidosis treatment affects the structure of the biofilm produced by B...

Biofilms are microbial communities composed of bacteria cells and self-produced extracellular polymeric substances and lead to antibiotic resistance, forming a great threat in the fields of medicine, food industries and so on. The formation of biofilms is a multi-stage dynamic process regulated by multiple mechanisms. Recently, researchers paid much more attention to the related research areas of biofilms, especially the detection methods of biofilms. This paper introduced the characteristics and formation process of biofilms as well as the effects of quorum sensing on biofilms development...

In recent years, Pseudomonas aeruginosa PAO1 emerged as the significant pathogenic microorganism in majority of the hospital-acquired infections due to its resistance to the conventional antibiotics by virtue of its highly organized quorum sensing and associated biofilm formation. In the present study, quorum sensing attenuation potential of Diaporthe phaseolorum SSP12 extract was investigated against P. aeruginosa PAO1 amply supported by molecular docking studies. D. phaseolorum SSP12 extract significantly inhibited the production of LasI/R mediated LasA protease, LasB elastase and chitinase with 66...

Bacterial colonization and biofilm formation on surfaces are typically mediated by the deposition of exopolysaccharides and conditioning protein layers. Pseudomonas aeruginosa is a nosocomial opportunistic pathogen that utilizes strain-specific exopolysaccharides such as Psl, Pel or alginate for both initial surface attachment and biofilm formation. To generate surfaces that resist P. aeruginosa colonization, we covalently bound a Psl-specific glycoside hydrolase (PslGh ) to several, chemically-distinct surfaces using amine functionalization (APTMS) and glutaraldehyde (GDA) linking...

Antibiotic resistance is one of the biggest threats to public health, and new antibacterial agents hence are in an urgent need to combat infectious diseases caused by multidrug-resistant (MDR) pathogens. Utilizing dimerization strategy, we rationally designed and efficiently synthesized a new series of small molecules-dimeric lysine alkylamides as mimics of AMPs. Evaluation of these mimics against a panel of Gram-positive and Gram-negative bacteria including MDR strains were performed, and a broad-spectrum and potent compound 3d was identified...

We investigated the numbers of planktonic and biofilm cells and the expression levels of genes encoding efflux pumps and biofilm-related proteins in 10 clinical isolates of multi-drug resistant Acinetobacter baumannii (MDRA) as well as in its standard strain ATCC 19606 in the presence of colistin (CST), polymyxin B (PMB), minomycin (MIN), and tigecycline (TGC) at their respective sub-MICs. The number of planktonic and biofilm cells of ATCC 19606 decreased in the presence of all aforementioned antibiotics in a dose-dependent manner...