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Small colony variant

Mingming Pu, Lili Sheng, Sooyeon Song, Ting Gong, Thomas K Wood
Pseudomonas aeruginosa causes many biofilm infections, and the rugose small-colony variants (RSCVs) of this bacterium are important for infection. We found here that inactivation of PA2444, which we determined to be a serine hydroxymethyltransferase (SHMT), leads to the RSCV phenotype of P. aeruginosa PA14. In addition, loss of PA2444 increases biofilm formation by two orders of magnitude, increases exopolysaccharide by 45-fold, and abolishes swarming. The RSCV phenotype is related to higher cyclic diguanylate concentrations due to increased activity of the Wsp chemosensory system, including diguanylate cyclase WspR...
2018: Frontiers in Microbiology
Yongjin Liu, Steven Kyle, Paul D Straight
Competitive interactions between bacteria reveal physiological adaptations that benefit fitness. Bacillus subtilis is a Gram-positive species with several adaptive mechanisms for competition and environmental stress. Biofilm formation, sporulation, and motility are the outcomes of widespread changes in a population of B. subtilis . These changes emerge from complex, regulated pathways for adapting to external stresses, including competition from other species. To identify competition-specific functions, we cultured B...
January 2018: MSphere
Lara Thieme, Mareike Klinger-Strobel, Anita Hartung, Claudia Stein, Oliwia Makarewicz, Mathias W Pletz
Background: Enterococci frequently cause severe biofilm-associated infections such as endocarditis. The combination of ampicillin/ceftriaxone has recently been clinically evaluated as non-inferior compared with the standard therapy of ampicillin/gentamicin for treatment of Enterococcus faecalis endocarditis. Ceftaroline is a novel cephalosporin with enhanced activity against Gram-positive bacteria. Objectives: To compare the in vitro effectiveness of the ceftaroline/ampicillin combination with those of gentamicin/ampicillin and ceftriaxone/ampicillin in planktonic and biofilm cultures of clinical E...
February 28, 2018: Journal of Antimicrobial Chemotherapy
Mathias Schwerdt, Claudia Neumann, Bianca Schwartbeck, Stefanie Kampmeier, Susann Herzog, Dennis Görlich, Angelika Dübbers, Jörg Große-Onnebrink, Christina Kessler, Peter Küster, Holger Schültingkemper, Janina Treffon, Georg Peters, Barbara C Kahl
BACKGROUND: Cystic fibrosis (CF) is an autosomal recessive disease associated with chronic airway infections by Staphylococcus aureus as one of the earliest and most prevalent pathogens. We conducted a retrospective study to determine the S. aureus infection status of CF patients treated since 1994 at two certified CF-centres in Münster, Germany, to get insights into the dynamics of S. aureus airway infection and the clinical impact on lung function on a long-term perspective. MATERIALS AND METHODS: We used data from our microbiological database collected between 1994 and 2016 for patients treated at two centres in Münster, Germany, respectively, to determine the infection status for S...
February 24, 2018: International Journal of Medical Microbiology: IJMM
Abdulrahman S Bazaid, Sarah Forbes, Gavin J Humphreys, Ruth G Ledder, Ronan O'Cualain, Andrew J McBain
Staphylococcus aureus can develop a small colony variant (SCV) phenotype in response to sub-lethal exposure to the biocide triclosan. In the current study, whole genome sequencing was performed and changes in virulence were investigated in five Staphylococcus aureus strains following repeated exposure to triclosan. Following exposure, 4/5 formed SCV and exhibited point mutations in the triclosan target gene fabI with 2/4 SCVs showing mutations in both fabI and fabD. The SCV phenotype was in all cases immediately reversed by nutritional supplementation with fatty acids or by repeated growth in the absence of triclosan, although fabI mutations persisted in 3/4 reverted SCVs...
March 1, 2018: Scientific Reports
Isabelle Guay, Simon Boulanger, Charles Isabelle, Eric Brouillette, Félix Chagnon, Kamal Bouarab, Eric Marsault, François Malouin
BACKGROUND: Tomatidine (TO) is a plant steroidal alkaloid that possesses an antibacterial activity against the small colony variants (SCVs) of Staphylococcus aureus. We report here the spectrum of activity of TO against other species of the Bacillales and the improved antibacterial activity of a chemically-modified TO derivative (FC04-100) against Listeria monocytogenes and antibiotic multi-resistant S. aureus (MRSA), two notoriously difficult-to-kill microorganisms. METHODS: Bacillus and Listeria SCVs were isolated using a gentamicin selection pressure...
February 13, 2018: BMC Pharmacology & Toxicology
Yunho Lee, Sooyeon Song, Lili Sheng, Lei Zhu, Jun-Seob Kim, Thomas K Wood
Filamentous phage impact biofilm development, stress tolerance, virulence, biofilm dispersal, and colony variants. Previously, we identified 137 Pseudomonas aeruginosa PA14 mutants with more than threefold enhanced and 88 mutants with more than 10-fold reduced biofilm formation by screening 5850 transposon mutants (PLoS Pathogens5: e1000483, 2009). Here, we characterized the function of one of these 225 mutations, dppA1 (PA14_58350), in regard to biofilm formation. DppA1 is a substrate-binding protein (SBP) involved in peptide utilization via the DppBCDF ABC transporter system...
2018: Frontiers in Microbiology
Romain Guérillot, Anders Gonçalves da Silva, Ian Monk, Stefano Giulieri, Takehiro Tomita, Eloise Alison, Jessica Porter, Sacha Pidot, Wei Gao, Anton Y Peleg, Torsten Seemann, Timothy P Stinear, Benjamin P Howden
Mutations in the beta-subunit of bacterial RNA polymerase (RpoB) cause resistance to rifampin (Rifr), a critical antibiotic for treatment of multidrug-resistant Staphylococcus aureus. In vitro studies have shown that RpoB mutations confer decreased susceptibility to other antibiotics, but the clinical relevance is unknown. Here, by analyzing 7,099 S. aureus genomes, we demonstrate that the most prevalent RpoB mutations promote clinically relevant phenotypic plasticity resulting in the emergence of stable S...
January 2018: MSphere
Matthew J Pestrak, Sarah B Chaney, Heather C Eggleston, Sheri Dellos-Nolan, Sriteja Dixit, Shomita S Mathew-Steiner, Sashwati Roy, Matthew R Parsek, Chandan K Sen, Daniel J Wozniak
Pseudomonas aeruginosa causes devastating infections in immunocompromised individuals. Once established, P. aeruginosa infections become incredibly difficult to treat due to the development of antibiotic tolerant, aggregated communities known as biofilms. A hyper-biofilm forming clinical variant of P. aeruginosa, known as a rugose small-colony variant (RSCV), is frequently isolated from chronic infections and is correlated with poor clinical outcome. The development of these mutants during infection suggests a selective advantage for this phenotype, but it remains unclear how this phenotype promotes persistence...
February 2, 2018: PLoS Pathogens
Evgeny A Idelevich, André Kriegeskorte, Nina Schleimer, Georg Peters, Christof von Eiff, Karsten Becker
Staphylococcus aureus small colony-variant (SCV) phenotype has been associated with relapsing and antibiotic-refractory infections. However, little is known about the activity of antibiotics on clinical SCVs. Here, we demonstrated that SCVs without detectable auxotrophies were at least as susceptible to most β-lactam and non-β-lactam antibiotics in vitro as their corresponding clonally identical strains with normal phenotype. After prolonged incubation, a regrowth phenomenon has been observed in gradient diffusion inhibition zones irrespective of the strains' phenotype...
January 29, 2018: Antimicrobial Agents and Chemotherapy
Elisabeth Fung, Kelly Hill, Katja Hogendoorn, Richard V Glatz, Kathryn R Napier, Matthew I Bellgard, Roberto A Barrero
Bee pollination is critical for improving productivity of one third of all plants or plant products consumed by humans. The health of honey bees is in decline in many countries worldwide, and RNA viruses together with other biological, environmental and anthropogenic factors have been identified as the main causes. The rapid genetic variation of viruses represents a challenge for diagnosis. Thus, application of deep sequencing methods for detection and analysis of viruses has increased over the last years. In this study, we leverage from the innate Dicer-2 mediated antiviral response against viruses to reconstruct complete viral genomes using virus-derived small interfering RNAs (vsiRNAs)...
January 26, 2018: Journal of Invertebrate Pathology
Nuntra Suwantarat, Mayer Rubin, Latetia Bryan, Tsigereda Tekle, Michael P Boyle, Karen C Carroll, Mark T Jennings
BACKGROUND: Small-colony variants (SCVs) are a distinct phenotype of Staphylococcus aureus, known for their role in chronic, difficult to treat infections, including cystic fibrosis (CF) lung disease. The goal of this study was to characterize SCV MRSA infection in an adult and pediatric CF population and to identify antibiotic susceptibility patterns unique to SCV MRSA. METHODS: We recovered methicillin-resistant S. aureus (MRSA) from respiratory culture samples from CF patients at the Johns Hopkins Hospital during a 6month study period...
December 2, 2017: Diagnostic Microbiology and Infectious Disease
Agnieszka Magryś, Agnieszka Bogut, Michał Kiełbus, Alina Olender
The objective of this study was to analyze how Staphylococcus epidermidis SCV and WT strains manipulate the PI3K/Akt/mTOR signaling pathway. Six S. epidermidis strains with normal phenotype (WT) and six S. epidermidis strains with SCV phenotype were isolated in parallel from six patients with the prosthetic hip joint infections. THP-1 activated cells were incubated with or without PI3K inhibitor-wortmannin or with mTOR inhibitor-rapamycin. Next, macrophages were exposed to S. epidermidis WT and SCV strains...
January 16, 2018: Immunological Investigations
Anthony A Adegoke, Thor A Stenström, Anthony I Okoh
Stenotrophomonas maltophilia is a commensal and an emerging pathogen earlier noted in broad-spectrum life threatening infections among the vulnerable, but more recently as a pathogen in immunocompetent individuals. The bacteria are consistently being implicated in necrotizing otitis, cutaneous infections including soft tissue infection and keratitis, endocarditis, meningitis, acute respiratory tract infection (RTI), bacteraemia (with/without hematological malignancies), tropical pyomyositis, cystic fibrosis, septic arthritis, among others...
2017: Frontiers in Microbiology
Hongbin Chen, Qi Wang, Yuyao Yin, Shuguang Li, Deng-Ke Niu, Hui Wang
Staphylococcus aureus small colony variants (SCVs) can cause persistent infections. However, the genomes and transcriptomes of S. aureus SCVs remain poorly understood. We isolated a pair of isogenic wild-type and SCV methicillin-resistant S. aureus (MRSA) strains (IE1 and IE2, respectively) from a patient with prosthetic valve infectious endocarditis. The SCV IE2 strain grew more slowly than the wild-type strain, and serum killing and mouse lethality assays revealed that the virulence of the SCV strain IE2 was decreased...
December 13, 2017: International Journal of Antimicrobial Agents
Silvia Di Lodovico, Angela Del Vecchio, Valentina Cataldi, Emanuela Di Campli, Soraya Di Bartolomeo, Luigina Cellini, Mara Di Giulio
In this study, the microbial contamination of smartphones from Italian University students was analyzed. A total of 100 smartphones classified as low, medium, and high emission were examined. Bacteria were isolated on elective and selective media and identified by biochemical tests. The mean values of cfu/cm2 were 0.79 ± 0.01; in particular, a mean of 1.21 ± 0.12, 0.77 ± 0.1 and 0.40 ± 0.10 cfu/cm2 was present on smartphones at low, medium, and high emission, respectively. The vast majority of identified microorganisms came from human skin, mainly Staphylococci, together with Gram-negative and positive bacilli and yeasts...
December 15, 2017: Current Microbiology
Thomas D Brekke, Katherine A Steele, John F Mulley
Non-model rodents are widely used as subjects for both basic and applied biological research, but the genetic diversity of the study individuals is rarely quantified. University-housed colonies tend to be small and subject to founder effects and genetic drift and so may be highly inbred or show substantial genetic divergence from other colonies, even those derived from the same source. Disregard for the levels of genetic diversity in an animal colony may result in a failure to replicate results if a different colony is used to repeat an experiment, as different colonies may have fixed alternative variants...
December 13, 2017: G3: Genes—Genomes—Genetics
Ping Zhang, John A Wright, Anna Tymon, Sean P Nair
Objectives: Staphylococcus aureus small colony variants (SCVs) cause persistent infections and are resistant to cationic antibiotics. Antimicrobial peptides (AMPs) have been suggested as promising alternatives for treating antibiotic-resistant bacteria. We investigated the capacity of the human cationic AMP LL-37 to kill SCVs in the presence of physiological concentrations of bicarbonate, which are reported to alter bacterial membrane permeability and change resistance of bacteria to AMPs...
December 4, 2017: Journal of Antimicrobial Chemotherapy
Tatsuya Tada, Kohei Uechi, Isamu Nakasone, Zenji Miyazato, Takashi Shinzato, Kayo Shimada, Mitsuhiro Tsuchiya, Teruo Kirikae, Jiro Fujita
Small-colony variants (SCVs) were obtained from an Enterobacter cloacae clinical isolate in Okinawa, Japan. One variant showed auxotrophy for hemin with a deletion of 20 365 nucleotides, dosC-ydiK-mmuP-mmuM-tauA-tauB-tauC-tauD-hemB-yaiT-yaiV-ampH-yddQ-sbmA-yaiW-yaiY-yaiZ, including hemB, and was more resistant to aminoglycosides and carbapenems, but more susceptible to aztreonam, than the parent strain.
January 2018: Journal of Medical Microbiology
Soyoung Kim, Kyung-Chan Kim, ChuHee Lee
BACKGROUND: Mistletoe extract of Visucm album extract (VAE) contains many biologically active components and has been reported to be not only a complementary and alternative medicine, but also a potent therapeutic agent for many types of cancer. PURPOSE: In this study, we examined the effect of VAE on expression and activation of Axl and scrutinized the involvement of Axl in the anti-cancer activity of VAE in parental and chemo-resistant non-small cell lung cancer (NSCLC) cells...
December 1, 2017: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
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