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Antibiotic Efflux

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https://www.readbyqxmd.com/read/27914962/efflux-mediated-colistin-resistance-in-diverse-clones-of-klebsiella-pneumoniae-from-aquatic-environment
#1
Santosh Kumar Singh, Mitali Mishra, Minu Sahoo, Shashank Patole, Harapriya Mohapatra
The peptide drug colistin is commonly used to treat carbapenem resistant gram negative bacterial infections. In the present study, we report efflux mediated colistin resistance in multidrug resistant Klebsiella pneumoniae isolates belonging to ST200 and ST1296, isolated from a fresh water environment. The isolates exhibited intermediate resistance to human serum, possessed Type 1 fimbriae and harbored blaSHV-34 and blaTEM-1 genes. Our results highlight the evolving nature of these clones in the country. These observations emphasize the need for judicious usage of antibiotics to prevent the imminent danger of losing out on currently available therapeutic options...
November 30, 2016: Microbial Pathogenesis
https://www.readbyqxmd.com/read/27909433/sponge-microbiota-are-a-reservoir-of-functional-antibiotic-resistance-genes
#2
Dennis Versluis, Mari Rodriguez de Evgrafov, Morten O A Sommer, Detmer Sipkema, Hauke Smidt, Mark W J van Passel
Wide application of antibiotics has contributed to the evolution of multi-drug resistant human pathogens, resulting in poorer treatment outcomes for infections. In the marine environment, seawater samples have been investigated as a resistance reservoir; however, no studies have methodically examined sponges as a reservoir of antibiotic resistance. Sponges could be important in this respect because they often contain diverse microbial communities that have the capacity to produce bioactive metabolites. Here, we applied functional metagenomics to study the presence and diversity of functional resistance genes in the sponges Aplysina aerophoba, Petrosia ficiformis, and Corticium candelabrum...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27902365/the-oral-cavities-of-healthy-infants-harbor-high-proportions-of-streptococcus-salivarius-strains-with-phenotypic-and-genotypic-resistance-to-multiple-classes-of-antibiotics
#3
Thaís H Palma, Erika Harth-Chú, Jodie Scott, Rafael N Stipp, Heike Boisvert, Mariana F Salomão, Jéssica D Theobaldo, Rosana F Possobon, Leandro C Nascimento, Jonathan W McCafferty, Lina Faller, Margaret J Duncan, Renata O Mattos-Graner
Emerging antibiotic resistance in the oropharyngeal microbiota, of which Streptococcus salivarius is a prominent species, represents a challenge for treating pediatric populations. In this study, we investigated the role of S. salivarius as a reservoir for antibiotic resistance genes (ARG) in the oral microbiota by analyzing 95 S. salivarius isolates from 22 healthy infants (2 to 16 months of age). Minimum inhibitory concentrations (MIC) of penicillin G, amoxicillin, erythromycin, tetracycline, doxycycline and streptomycin were determined...
October 24, 2016: Journal of Medical Microbiology
https://www.readbyqxmd.com/read/27895902/effect-of-%C3%AE-lactamase-inhibitors-on-in-vitro-activity-of-%C3%AE-lactam-antibiotics-against-burkholderia-cepacia-complex-species
#4
Annelien Everaert, Tom Coenye
BACKGROUND: Bacteria belonging to the Burkholderia cepacia complex (Bcc) are an important cause of chronic respiratory tract infections in cystic fibrosis patients. Intrinsic resistance to a wide range of antimicrobial agents, including a variety of β-lactam antibiotics, is frequently observed in Bcc strains. Resistance to β-lactams is most commonly mediated by efflux pumps, alterations in penicillin-binding proteins or the expression of β-lactamases. β-lactamase inhibitors are able to restore the in vitro activity of β-lactam molecules against a variety of Gram-negative species, but the effect of these inhibitors on the activity of β-lactam treatment against Bcc species is still poorly investigated...
2016: Antimicrobial Resistance and Infection Control
https://www.readbyqxmd.com/read/27892739/efflux-as-a-mechanism-of-antimicrobial-drug-resistance-in-clinical-relevant-microorganisms-the-role-of-efflux-inhibitors
#5
Clarissa Willers, Johannes Frederik Wentzel, Lissinda Hester du Plessis, Chrisna Gouws, Josias Hendrik Hamman
Microbial resistance against antibiotics is a serious threat to the effective treatment of infectious diseases. Several mechanisms exist through which microorganisms can develop resistance against antimicrobial drugs, of which the over-expression of genes to produce efflux pumps is a major concern. Several efflux transporters have been identified in microorganisms, which infer resistance against specific antibiotics and even multi-drug resistance. Areas covered: This paper focuses on microbial resistance against antibiotics by means of the mechanism of efflux and gives a critical overview of studies conducted to overcome this problem by combining efflux pump inhibitors with antibiotics...
November 28, 2016: Expert Opinion on Therapeutic Targets
https://www.readbyqxmd.com/read/27889248/comprehensive-study-to-investigate-the-role-of-various-aminoglycoside-resistance-mechanisms-in-clinical-isolates-of-acinetobacter-baumannii
#6
Vajihe Sheikhalizadeh, Alka Hasani, Mohammad Ahangarzadeh Rezaee, Mohammad Rahmati-Yamchi, Akbar Hasani, Reza Ghotaslou, Hamid Reza Goli
Therapeutic resistance towards most of the current treatment regime by Acinetobacter baumannii has reduced the prescribing antibiotic pattern and option is being re-shifted towards more toxic agents including aminoglycosides. The present investigation aimed at to study various mechanisms towards aminoglycoside non-susceptibility in clinical isolates of A. baumannii. The bacteria were subjected to genetic basis assessment for the presence of aminoglycoside modifying enzymes (AME), 16S rRNA methylase encoding genes and relative expression of AdeABC and AbeM efflux pumps in relation to their susceptibility to five aminoglycosides...
November 23, 2016: Journal of Infection and Chemotherapy: Official Journal of the Japan Society of Chemotherapy
https://www.readbyqxmd.com/read/27889169/characterization-of-biocide-tolerant-bacteria-isolated-from-cheese-and-dairy-small-medium-enterprises
#7
Ma Luisa Fernández Márquez, Ma José Grande Burgos, Ma Carmen López Aguayo, Rubén Pérez Pulido, Antonio Gálvez, Rosario Lucas
A collection of 120 bacterial isolates from small medium enterprises involved in the production of cow milk and the manufacture of goat cheese were screened for sensitivity to biocides benzalkonium chloride (BC), cetrimide (CT), hexadecylpyridinium chloride (HDP), triclosan (TC), hexachlorophene (CF) and poly-(hexamethylen guanidinium) hydrochloride (PHMG). Nineteen isolates were selected according to biocide tolerance and identified by 16S rDNA sequencing as Lactococcus sp. (6) Enterococcus sp. (1), Lactobacillus sp...
April 2017: Food Microbiology
https://www.readbyqxmd.com/read/27879336/beyond-antimicrobial-resistance-evidence-for-a-distinct-role-of-the-acrd-efflux-pump-in-salmonella-biology
#8
Michelle M C Buckner, Jessica M A Blair, Roberto M La Ragione, Jane Newcombe, Daniel J Dwyer, Alasdair Ivens, Laura J V Piddock
: For over 20 years, bacterial multidrug resistance (MDR) efflux pumps have been studied because of their impact on resistance to antimicrobials. However, critical questions remain, including why produce efflux pumps under non-antimicrobial treatment conditions, and why have multiple pumps if their only purpose is antimicrobial efflux? Salmonella spp. possess five efflux pump families, including the resistance-nodulation-division (RND) efflux pumps. Notably, the RND efflux pump AcrD has a unique substrate profile, distinct from other Salmonella efflux pumps...
November 22, 2016: MBio
https://www.readbyqxmd.com/read/27876418/polycyclic-aromatic-hydrocarbons-pahs-enriching-antibiotic-resistance-genes-args-in-the-soils
#9
Baowei Chen, Rong He, Ke Yuan, Enzhong Chen, Lan Lin, Xin Chen, Sha Sha, Jianan Zhong, Li Lin, Lihua Yang, Ying Yang, Xiaowei Wang, Shichun Zou, Tiangang Luan
The prevalence of antibiotic resistance genes (ARGs) in modern environment raises an emerging global health concern. In this study, soil samples were collected from three sites in petrochemical plant that represented different pollution levels of polycyclic aromatic hydrocarbons (PAHs). Metagenomic profiling of these soils demonstrated that ARGs in the PAHs-contaminated soils were approximately 15 times more abundant than those in the less-contaminated ones, with Proteobacterial being the preponderant phylum...
November 19, 2016: Environmental Pollution
https://www.readbyqxmd.com/read/27874224/multiple-transporters-are-involved-in-natamycin-efflux-in-streptomyces-chattanoogensis-l10
#10
Tan-Jun Wang, Yi-Ming Shan, Han Li, Wei-Wang Dou, Xin-Hang Jiang, Xu-Ming Mao, Shui-Ping Liu, Wen-Jun Guan, Yong-Quan Li
Antibiotic-producing microorganisms have evolved several self-resistance mechanisms to prevent auto-toxicity. Overexpression of specific transporters to improve the efflux of toxic antibiotics has been found one of the most important and intrinsic resistance strategies employed by many Streptomyces strains. In this work, two ATP-binding cassette (ABC) transporter-encoding genes located in the natamycin biosynthetic gene cluster, scnA and scnB, were identified as the primary exporter genes for natamycin efflux in Streptomyces chattanoogensis L10...
November 22, 2016: Molecular Microbiology
https://www.readbyqxmd.com/read/27870879/occurrence-of-diverse-antimicrobial-resistance-determinants-in-genetically-unrelated-biocide-tolerant-klebsiella-pneumoniae
#11
Amitabha Mondal, Manjunath Venkataramaiah, Govindan Rajamohan, Vijaya Bharathi Srinivasan
Nosocomial infections due to Klebsiella pneumoniae is a significant problem in health care settings worldwide. In this study, we examined the antimicrobial susceptibility, genetic profiles and mechanisms of antibiotic resistance in K. pneumoniae isolates of Indian origin. To our knowledge this is the first report demonstrating the high prevalence of β-lactamases, aminoglycoside modifying enzymes, quinolone resistance genes besides demonstrating the involvement of active efflux in K. pneumoniae Indian isolates...
2016: PloS One
https://www.readbyqxmd.com/read/27869748/design-of-new-antibacterial-enhancers-based-on-acrb-s-structure-and-the-evaluation-of-their-antibacterial-enhancement-activity
#12
Yi Song, Rongxin Qin, Xichun Pan, Qin Ouyang, Tianyu Liu, Zhaoxia Zhai, Yingchun Chen, Bin Li, Hong Zhou
Previously, artesunate (AS) and dihydroartemisinine 7 (DHA7) were found to have antibacterial enhancement activity against Escherichia coli via inhibition of the efflux pump AcrB. However, they were only effective against E. coli standard strains. This study aimed to develop effective antibacterial enhancers based on the previous work. Our results demonstrate that 86 new antibacterial enhancers were designed via 3D-SAR and molecular docking. Among them, DHA27 had the best antibacterial enhancement activity...
November 18, 2016: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/27866817/discovery-of-novel-n-phenyl-1-4-dihydropyridines-with-a-dual-mode-of-antimycobacterial-activity
#13
Fabian Lentz, Marc Hemmer, Norbert Reiling, Andreas Hilgeroth
There is an urgent need for novel drugs for the treatment of tuberculosis (TB) due to the increasing prevalence of antibiotic resistance among Mycobacterium tuberculosis (Mtb) strains against first-line and second-line therapeutics. We developed novel N-phenyl 1,4-dihydropyridines as potential antituberculotic agents. The observed activity depends on the substitution patterns of the aromatic residues. N-unsubstituted 1,4-dihydropyridines are known inhibitors of the cancer-relevant transmembrane efflux pump ABCB1...
December 15, 2016: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/27855067/tigecycline-non-susceptibility-occurs-exclusively-in-fluoroquinolone-resistant-escherichia-coli-clinical-isolates-including-the-major-multidrug-resistant-lineages-o25b-h4-st131-h30r-and-o1-st648
#14
Toyotaka Sato, Yuuki Suzuki, Tsukasa Shiraishi, Hiroyuki Honda, Masaaki Shinagawa, Soh Yamamoto, Noriko Ogasawara, Hiroki Takahashi, Satoshi Takahashi, Yutaka Tamura, Shin-Ichi Yokota
Tigecycline (TGC) is a last-line drug for multidrug-resistant Enterobacteriaceae. We investigated the mechanism(s) underlying TGC non-susceptibility (TGC-resistance/intermediate) in Escherichia coli clinical isolates. The MIC of TGC was determined for 277 fluoroquinolone-susceptible isolates (ciprofloxacin [CIP] MIC: <0.125 mg/L, and 194 fluoroquinolone-resistant isolates (CIP MIC: >2 mg/L). The MIC50 and MIC90 for TGC in fluoroquinolone-resistant isolates were 2-fold higher than those in fluoroquinolone-susceptible isolates (MIC50: 0...
November 14, 2016: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/27845849/an-experimental-model-for-the-rapid-screening-of-compounds-with-potential-use-against-mycobacteria
#15
Sofia Santos Costa, Elizeth Lopes, Elisa Azzali, Diana Machado, Tatiane Coelho, Pedro Eduardo Almeida da Silva, Miguel Viveiros, Marco Pieroni, Isabel Couto
Infections caused by Mycobacterium tuberculosis and other mycobacteria are major challenges for global public health. Particularly worrisome are infections caused by multidrug-resistant bacteria, which are increasingly difficult to treat because of the loss of efficacy of the current antibacterial agents, a problem that continues to escalate worldwide. There has been a limited interest and investment on the development of new antibacterial agents in the past decades. This has led to the current situation, in which there is an urgent demand for innovative therapeutic alternatives to fight infections caused by multidrug-resistant pathogens, such as multidrug-resistant tuberculosis...
November 2016: Assay and Drug Development Technologies
https://www.readbyqxmd.com/read/27842757/in-vitro-reduction-of-antibacterial-activity-of-tigecycline-against-multidrug-resistant-acinetobacter-baumannii-with-host-stress-hormone-norepinephrine
#16
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...
November 4, 2016: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/27835840/correlation-between-the-number-of-pro-ala-repeats-in-the-emra-homologue-of-acinetobacter-baumannii-and-resistance-to-netilmicin-tobramycin-imipenem-and-ceftazidime
#17
Alicja Nowak-Zaleska, Miłosz Wieczór, Jacek Czub, Łukasz Nierzwicki, Roman Kotłowski, Agnieszka Mikucka, Eugenia Gospodarek
Acinetobacter baumannii coccobacilli are dangerous to patients in intensive care units because of their multidrug resistance to antibiotics, developed mainly in the past decade. This study aimed to examine whether there is a significant correlation between the number of Pro-Ala repeats in the CAP01997 protein, the EmrA homologue of A. baumannii, and resistance to antibiotics. A total of 79 multidrug-resistant A. baumannii strains isolated from patients were analysed. Resistance to antibiotics was determined on Mueller-Hinton agar plates using the Kirby-Bauer disk diffusion method...
December 2016: Journal of Global Antimicrobial Resistance
https://www.readbyqxmd.com/read/27830269/inhibition-of-the-multidrug-efflux-pump-lmrs-from-staphylococcus-aureus-by-cumin-spice-cuminum-cyminum
#18
Prathusha Kakarla, Jared Floyd, MunMun Mukherjee, Amith R Devireddy, Madhuri A Inupakutika, Indrika Ranweera, Ranjana Kc, Ugina 'Shrestha, Upender Rao Cheeti, Thomas Mark Willmon, Jaclyn Adams, Merissa Bruns, Shravan Kumar Gunda, Manuel F Varela
Staphylococcus aureus is a serious causative agent of infectious disease. Multidrug-resistant strains like methicillin-resistant S. aureus compromise treatment efficacy, causing significant morbidity and mortality. Active efflux represents a major antimicrobial resistance mechanism. The proton-driven multidrug efflux pump, LmrS, actively exports structurally distinct antimicrobials. To circumvent resistance and restore clinical efficacy of antibiotics, efflux pump inhibitors are necessary, and natural edible spices like cumin are potential candidates...
November 9, 2016: Archives of Microbiology
https://www.readbyqxmd.com/read/27823890/new-amphiphilic-neamine-conjugates-bearing-a-metal-binding-motif-active-against-mdr-e-%C3%A2-aerogenes-gram-negative-bacteria
#19
Anas Allam, Laure Maigre, Rodolphe Alves de Sousa, Estelle Dumont, Julia Vergalli, Jean-Marie Pagès, Isabelle Artaud
Structure of bacterial envelope is one of the major factors contributing to Gram negative bacterial resistance. To develop new agents that target the bacterial membranes, we synthesized, by analogy with our previous peptide conjugates, new amphiphilic 3',4',6-trinaphthylmethylene neamines functionalized at position 5 through a short spacer by a chelating group, tris(2-pyridylmethyl)amine (TPA) and di-(picolyl)amine (DPA) and tetraazacyclotetradecane (Cyclam). ESI(+) mass spectrometry analyses showed that neither Zn(II)(NeaDPA) nor Cu(II)(NeaCyclam) were stable in the Mueller Hinton (MH) medium used for antibacterial assays...
October 25, 2016: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/27821607/novel-rpos-dependent-mechanisms-strengthen-the-envelope-permeability-barrier-during-stationary-phase
#20
Angela M Mitchell, Wei Wang, Thomas J Silhavy
: Gram-negative bacteria have effective methods of excluding toxic compounds including a largely impermeable outer membrane (OM) and a range of efflux pumps. Furthermore, when cells become nutrient-limited, RpoS enacts a global expression change providing cross-protection against many stresses. Here, we utilized sensitivity to an anionic detergent (sodium dodecyl sulfate, SDS) to model probe changes occurring to the cell's permeability barrier during nutrient limitation. Escherichia coli is resistant to SDS whether cells are actively growing, carbon-limited, or nitrogen-limited...
November 7, 2016: Journal of Bacteriology
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