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biofilm and efflux pump

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https://www.readbyqxmd.com/read/28621579/optimization-of-antimicrobial-photodynamic-therapy-in-biofilms-by-inhibiting-efflux-pump
#1
Tatiana Maria Starck Fogaça de Aguiar Coletti, Laura Marise de Freitas, Ana Marisa Fusco Almeida, Carla Raquel Fontana
BACKGROUND: One of the main mechanisms of microbial resistance is given by efflux pumps, which reduce the effectiveness of antimicrobials by decreasing their intracellular concentration. OBJECTIVE AND METHODS: Considering that efflux pump inhibitors are promising adjuvant molecules for antibiotics in infections, in this study, using XTT test and colony forming unit (CFU) counting, we evaluated the association between the pump inhibitor verapamil (VP) and the antimicrobial photodynamic therapy (aPDT) mediated by methylene blue (MB) in biofilms of Escherichia coli and Staphylococcus aureus to optimize the bacterial reduction...
June 15, 2017: Photomedicine and Laser Surgery
https://www.readbyqxmd.com/read/28618136/amphiphilic-cargo-loaded-nanocarrier-enhances-antibiotic-uptake-and-perturbs-efflux-effective-synergy-for-mitigation-of-methicillin-resistant-staphylococcus-aureus
#2
Durairaj Thiyagarajan, Gopal Das, Ramesh Aiyagari
A pyridinium amphiphile-loaded Poly(lactic-co-glycolic acid) (PLGA) nanocarrier (C1-PNC) was developed as an adjuvant in order to break the resistance and restore susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) cells to therapeutic antibiotics. Notably, against a clinical MRSA strain, C1-PNC could render 8 × and 6 × reduction of the minimum biofilm eradication concentration (MBEC90) of gentamicin and ciprofloxacin, respectively. Mechanistic studies on MRSA planktonic cells revealed that in case of gentamicin, C1-PNC promoted enhanced cellular uptake of the antibiotic, while the propensity of C1-PNC to inhibit efflux pump activity could be leveraged to enhance cellular accumulation of ciprofloxacin leading to effective killing of MRSA cells...
June 15, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28587519/inactivation-of-a-putative-efflux-pump-lmrb-in-streptococcus-mutans-results-in-altered-biofilm-structure-and-increased-exopolysaccharide-synthesis-implications-for-biofilm-resistance
#3
Jia Liu, Jianying Zhang, Lihong Guo, Wei Zhao, Xiaoli Hu, Xi Wei
Efflux pumps are a mechanism associated with biofilm formation and resistance. There is limited information regarding efflux pumps in Streptococcus mutans, a major pathogen in dental caries. The aim of this study was to investigate potential roles of a putative efflux pump (LmrB) in S. mutans biofilm formation and susceptibility. Upon lmrB inactivation and antimicrobial exposure, the biofilm structure and expression of other efflux pumps were examined using confocal laser scanning microscopy (CLSM) and qRT-PCR...
June 7, 2017: Biofouling
https://www.readbyqxmd.com/read/28584154/pa3225-is-a-transcriptional-repressor-of-antibiotic-resistance-mechanisms-in-pseudomonas-aeruginosa
#4
Clayton W Hall, Li Zhang, Thien-Fah Mah
The tssABC1 locus is part of the Hcp secretion island (HSI) -I type VI secretion system (T6SS) in Pseudomonas aeruginosa Previous work has implicated the tssC1 gene in P. aeruginosa biofilm-specific antibiotic resistance, and tssC1 is preferentially expressed in biofilms compared to planktonic cells. Using a DNA-dependent protein pulldown approach, we discovered PA3225, an uncharacterised LysR-type transcriptional regulator that specifically bound to the tssABC1 upstream regulatory region. Deletion of PA3225 led to a two-fold decrease in tssA1 expression in planktonic cells compared to wild-type, and tssA1 expression was slightly reduced in ΔPA3225 biofilms compared to wild-type biofilms...
June 5, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28536672/response-to-bile-salts-in-clinical-strains-of-acinetobacter-baumannii-lacking-the-adeabc-efflux-pump-virulence-associated-with-quorum-sensing
#5
Maria López, Lucia Blasco, Eva Gato, Astrid Perez, Laura Fernández-Garcia, Luis Martínez-Martinez, Felipe Fernández-Cuenca, Jesús Rodríguez-Baño, Alvaro Pascual, German Bou, Maria Tomás
Introduction:Acinetobacter baumannii is an opportunistic nosocomial pathogen associated with multiple infections. This pathogen usually colonizes (first stage of microbial infection) host tissues that are in contact with the external environment. As one of the sites of entry in human hosts is the gastrointestinal tract, the pathogen must be capable of tolerating bile salts. However, studies analyzing the molecular characteristics involved in the response to bile salts in clinical strains of A. baumannii are scarce...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28534862/differences-in-gene-expression-profiles-between-early-and-late-isolates-in-monospecies-achromobacter-biofilm
#6
Signe M Nielsen, Rikke L Meyer, Niels Nørskov-Lauritsen
Bacteria of genus Achromobacter are emerging pathogens in cystic fibrosis (CF) capable of biofilm formation and development of antimicrobial resistance. Evolutionary adaptions in the transition from primary to chronic infection were assessed by transcriptomic analysis of successive isolates of Achromobacter xylosoxidans from a single CF patient. Several efflux pump systems targeting antimicrobial agents were upregulated during the course of the disease, whereas all genes related to motility were downregulated...
May 19, 2017: Pathogens
https://www.readbyqxmd.com/read/28486078/characterization-of-clinically-isolated-antibiotic-resistant-salmonella-typhimurium-exposed-to-subinhibitory-concentrations-of-ceftriaxone-and-ciprofloxacin
#7
Jeongjin Kim, Juhee Ahn
This study was designed mainly to assess the phenotypic properties of clinically isolated Salmonella Typhimurium exposed to ceftriaxone and ciprofloxacin. The antibiotic susceptibility, β-lactamase activity, efflux activity, bacterial motility, biofilm-forming ability, and gene expression were determined in S. Typhimurium ATCC 19585 and S. Typhimurium CCARM 8009 when exposed to subinhibitory concentrations of ceftriaxone and ciprofloxacin. S. Typhimurium CCARM 8009 was highly resistant to ampicillin, kanamycin, penicillin G, and streptomycin, showing minimum inhibitory concentration values of more than 512 μg/ml, while S...
May 9, 2017: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
https://www.readbyqxmd.com/read/28476775/defining-genetic-fitness-determinants-and-creating-genomic-resources-for-an-oral-pathogen
#8
Ajay M Narayanan, Matthew M Ramsey, Apollo Stacy, Marvin Whiteley
Periodontitis is a microbial infection that destroys the structures that support the teeth. Although typically a chronic condition, rapidly progressing, aggressive forms are associated with the oral pathogen Aggregatibacter actinomycetemcomitans One of this bacterium's key virulence traits is its ability to attach to surfaces and form robust biofilms that resist killing by the host and antibiotics. Though much has been learned about A. actinomycetemcomitans since its initial discovery, we lack insight into a fundamental aspect of its basic biology, as we do not know the full set of genes that it requires for viability (essential genome)...
May 5, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28437232/epidemiological-physiological-and-molecular-characteristics-of-a-brazilian-collection-of-carbapenem-resistant-acinetobacter-baumannii-and-pseudomonas-aeruginosa
#9
Vanessa Cordeiro Dias, Juliana Alves Resende, André Netto Bastos, Lucas Quinet De Andrade Bastos, Victor Quinet De Andrade Bastos, Ricardo Villela Bastos, Cláudio Galuppo Diniz, Vânia Lúcia Da Silva
Nonfermenting Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii are widespread in the environment and are increasingly associated with nosocomial infections, often associated with multidrug-resistance phenotypes. This study aimed to evaluate epidemiological, physiological, and molecular characteristics of carbapenem resistance in P. aeruginosa and A. baumannii. In total, 63 nonreplicated strains (44 A. baumannii and 19 P. aeruginosa) were isolated from hospitalized patients. Antimicrobial resistance patterns, biocide tolerance, oxidative stress, hemolytic activity, and biofilm formation were assessed...
February 24, 2017: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
https://www.readbyqxmd.com/read/28436748/disruption-of-tetr-type-regulator-aden-by-mobile-genetic-element-confers-elevated-virulence-in-acinetobacter-baumannii
#10
Rajagopalan Saranathan, Sudhakar Pagal, Ajit R Sawant, Archana Tomar, M Madhangi, Suresh Sah, Annapurna Satti, K P Arunkumar, K Prashanth
Acinetobacter baumannii is an important human pathogen and considered as a major threat due to its extreme drug resistance. In this study, the genome of a hyper-virulent MDR strain PKAB07 of A. baumannii isolated from an Indian patient was sequenced and analyzed to understand its mechanisms of virulence, resistance and evolution. Comparative genome analysis of PKAB07 revealed virulence and resistance related genes scattered throughout the genome, instead of being organized as an island, indicating the highly mosaic nature of the genome...
April 24, 2017: Virulence
https://www.readbyqxmd.com/read/28348056/analysis-of-shigella-flexneri-resistance-biofilm-formation-and-transcriptional-profile-in-response-to-bile-salts
#11
Kourtney P Nickerson, Rachael B Chanin, Jeticia R Sistrunk, David A Rasko, Peter J Fink, Eileen M Barry, James P Nataro, Christina S Faherty
The Shigella species cause millions of cases of watery or bloody diarrhea each year, mostly in children in developing countries. While many aspects of Shigella colonic cell invasion are known, crucial gaps in knowledge regarding how the bacteria survive, transit, and regulate gene expression prior to infection remain. In this study, we define mechanisms of resistance to bile salts and build on previous research highlighting induced virulence in Shigella flexneri strain 2457T following exposure to bile salts...
June 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28289081/light-modulates-metabolic-pathways-and-other-novel-physiological-traits-in-the-human-pathogen-acinetobacter-baumannii
#12
Gabriela L Müller, Marisel Tuttobene, Matías Altilio, Maitena Martínez Amezaga, Meaghan Nguyen, Pamela Cribb, Larisa E Cybulski, María Soledad Ramírez, Silvia Altabe, María Alejandra Mussi
Light sensing in chemotrophic bacteria has been relatively recently ascertained. In the human pathogen Acinetobacter baumannii, light modulates motility, biofilm formation, and virulence through the blue-light-sensing-using flavin (BLUF) photoreceptor BlsA. In addition, light can induce a reduction in susceptibility to certain antibiotics, such as minocycline and tigecycline, in a photoreceptor-independent manner. In this work, we identified new traits whose expression levels are modulated by light in this pathogen, which comprise not only important determinants related to pathogenicity and antibiotic resistance but also metabolic pathways, which represents a novel concept for chemotrophic bacteria...
May 15, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28275296/effect-of-biofilm-formation-by-clinical-isolates-of-helicobacter-pylori-on-the-efflux-mediated-resistance-to-commonly-used-antibiotics
#13
Bahareh Attaran, Tahereh Falsafi, Nassim Ghorbanmehr
AIM: To evaluate the role of biofilm formation on the resistance of Helicobacter pylori (H. pylori) to commonly prescribed antibiotics, the expression rates of resistance genes in biofilm-forming and planktonic cells were compared. METHODS: A collection of 33 H. pylori isolates from children and adult patients with chronic infection were taken for the present study. The isolates were screened for biofilm formation ability, as well as for polymerase chain reaction (PCR) reaction with HP1165 and hp1165 efflux pump genes...
February 21, 2017: World Journal of Gastroenterology: WJG
https://www.readbyqxmd.com/read/28270804/eradication-and-sensitization-of-methicillin-resistant-staphylococcus-aureus-to-methicillin-with-bioactive-extracts-of-berry-pomace
#14
Serajus Salaheen, Mengfei Peng, Jungsoo Joo, Hironori Teramoto, Debabrata Biswas
The therapeutic roles of phenolic blueberry (Vaccinium corymbosum) and blackberry (Rubus fruticosus) pomace (commercial byproduct) extracts (BPE) and their mechanism of actions were evaluated against methicillin resistant Staphylococcus aureus (MRSA). Five major phenolic acids of BPE, e.g., protocatechuic, p. coumaric, vanillic, caffeic, and gallic acids, as well as crude BPE completely inhibited the growth of vegetative MRSA in vitro while BPE+methicillin significantly reduced MRSA biofilm formation on plastic surface...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28138373/resistance-of-candida-albicans-biofilms-to-drugs-and-the-host-immune-system
#15
REVIEW
Doblin Sandai, Yasser M Tabana, Ahmad El Ouweini, Ishola Oluwaseun Ayodeji
BACKGROUND: Candida albicans is a commensal fungus that resides on mucosal surfaces and in the gastrointestinal and genitourinary tracts in humans. However, it can cause an infection when the immune system of the host is impaired or if a niche becomes available. Many C. albicans infections are due to the organism's ability to form a biofilm on implanted medical devices. A biofilm represents an optimal medium for the growth of C. albicans as it allows cells to be enclosed by a self-produced extracellular matrix (ECM)...
November 2016: Jundishapur Journal of Microbiology
https://www.readbyqxmd.com/read/28062292/use-of-carvacrol-thymol-and-eugenol-for-biofilm-eradication-and-resistance-modifying-susceptibility-of-salmonella-enterica-serovar-typhimurium-strains-to-nalidixic-acid
#16
Hanene Miladi, Tarek Zmantar, Bochra Kouidhi, Yassine Chaabouni, Kacem Mahdouani, Amina Bakhrouf, Kamel Chaieb
The Aims of the study was to evaluate the antibacterial susceptibility and the biofilm eradication of three natural compounds carvacrol (CAR), thymol (TH) and eugenol (EUG), alone or in combination with nalidixic acid (NA) against twelve Salmonella Typhimurium strains. The minimum inhibitory concentration (MIC) and the minimum biofilm eradication concentration (BEC50) of the tested compounds (CAR, TH and EUG) and their combinations with NA were evaluated. In order to assess whether these bacteria had active efflux pumps, ethidium bromide (EtBr) accumulation assays was achieved using spectrophotometric accumulation assays...
March 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/27986731/novel-cadmium-resistance-determinant-in-listeria-monocytogenes
#17
Cameron Parsons, Sangmi Lee, Victor Jayeola, Sophia Kathariou
Listeria monocytogenes is a foodborne pathogen that can cause severe disease (listeriosis) in susceptible individuals. It is ubiquitous in the environment and often exhibits resistance to heavy metals. One of the determinants that enables Listeria to tolerate exposure to cadmium is the cadAC efflux system, with CadA being a P-type ATPase. Three different cadA genes (designated cadA1 to cadA3) were previously characterized in L. monocytogenes A novel putative cadmium resistance gene (cadA4) was recently identified through whole-genome sequencing, but experimental confirmation for its involvement in cadmium resistance is lacking...
March 1, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/27936915/promethazine-improves-antibiotic-efficacy-and-disrupts-biofilms-of-burkholderia-pseudomallei
#18
José Júlio Costa Sidrim, David Caldas Vasconcelos, Giovanna Barbosa Riello, Glaucia Morgana de Melo Guedes, Rosana Serpa, Tereza de Jesus Pinheiro Gomes Bandeira, André Jalles Monteiro, Rossana de Aguiar Cordeiro, Débora de Souza Collares Maia Castelo-Branco, Marcos Fábio Gadelha Rocha, Raimunda Sâmia Nogueira Brilhante
Efflux pumps are important defense mechanisms against antimicrobial drugs and maintenance of Burkholderia pseudomallei biofilms. This study evaluated the effect of the efflux pump inhibitor promethazine on the structure and antimicrobial susceptibility of B. pseudomallei biofilms. Susceptibility of planktonic cells and biofilms to promethazine alone and combined with antimicrobials was assessed by the broth microdilution test and biofilm metabolic activity was determined with resazurin. The effect of promethazine on 48 h-grown biofilms was also evaluated through confocal and electronic microscopy...
January 2017: Biofouling
https://www.readbyqxmd.com/read/27884783/secondary-multidrug-efflux-pump-mutants-alter-escherichia-coli-biofilm-growth-in-the-presence-of-cationic-antimicrobial-compounds
#19
Denice C Bay, Carol A Stremick, Carmine J Slipski, Raymond J Turner
Escherichia coli possesses many secondary active multidrug resistance transporters (MDTs) that confer overlapping substrate resistance to a broad range of antimicrobials via proton and/or sodium motive force. It is uncertain whether redundant MDTs uniquely alter cell survival when cultures grow planktonically or as biofilms. In this study, the planktonic and biofilm growth and antimicrobial resistance of 13 E. coli K-12 single MDT gene deletion strains in minimal and rich media were determined. Antimicrobial tolerance to tetracycline, tobramycin and benzalkonium were also compared for each ΔMDT strain...
April 2017: Research in Microbiology
https://www.readbyqxmd.com/read/27842757/in-vitro-reduction-of-antibacterial-activity-of-tigecycline-against-multidrug-resistant-acinetobacter-baumannii-with-host-stress-hormone-norepinephrine
#20
Masato Inaba, Naoyuki Matsuda, Hirotsugu Banno, Wanchun Jin, Jun-Ichi Wachino, Keiko Yamada, Kouji Kimura, Yoshichika Arakawa
The host stress hormone norepinephrine (NE), also called noradrenaline, is reported to augment bacterial growth and pathogenicity, but few studies have focused on the effect of NE on the activity of antimicrobials. The aim of this study was to clarify whether NE affects antimicrobial activity against multidrug-resistant Acinetobacter baumannii (MDR-AB). Time-kill studies of tigecycline (TIG) and colistin (COL) against MDR-AB as well as assays for factors contributing to antibiotic resistance were performed using MDR-AB clinical strains both in the presence and absence of 10 µM NE...
December 2016: International Journal of Antimicrobial Agents
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