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Small colony variant

Maximilian Neugebauer, Jana K Böcker, Julian C J Matern, Shmuel Pietrokovski, Henning D Mootz
Protein splicing by inteins has found diverse applications in biotechnology, protein chemistry and chemical biology. Inteins display a wide range of efficiencies and rates unpredictable from their amino acid sequences. Here, we identified positions T22S and S35 in the LacZα peptide as intein insertion sites that strictly require protein splicing, in contrast to cleavage side-reactions, to allow for complementation of β-galactosidase activity. Both the cis-variant of the M86 mutant of the Ssp DnaB intein and a split form undergoing protein trans-splicing gave rise to formation of blue colonies in the β-galactosidase read-out...
September 15, 2016: Biological Chemistry
Ricardo S Ramiro, Henrique Costa, Isabel Gordo
Small-colony variants (SCVs) are commonly observed in evolution experiments and clinical isolates, being associated with antibiotic resistance and persistent infections. We recently observed the repeated emergence of Escherichia coli SCVs during adaptation to the interaction with macrophages. To identify the genetic targets underlying the emergence of this clinically relevant morphotype, we performed whole-genome sequencing of independently evolved SCV clones. We uncovered novel mutational targets, not previously associated with SCVs (e...
September 2016: Evolutionary Applications
Sha Liu, Xue-Xian Zhang
Applying self-sanitising copper surfaces to commonly touched places within hospital facilities is an emerging strategy to prevent healthcare-associated infections (HAIs). This is owing to the fact that bacterial pathogens are rapidly killed on copper, a process termed contact killing. However, the mechanisms of contact killing are not fully understood, and the potential of bacterial pathogens to develop resistance has rarely been explored. Here, we hypothesize that bacteria are predominantly killed by a burst release of toxic copper ions, resulting from chemical reactions between bacterial cell surface components and metallic copper...
September 2, 2016: Journal of Medical Microbiology
R Kc, A Srivastava, J M Wilkowski, C E Richter, J A Shavit, D T Burke, S L Bielas
CRISPR/Cas9 genome-editing has emerged as a powerful tool to create mutant alleles in model organisms. However, the precision with which these mutations are created has introduced a new set of complications for genotyping and colony management. Traditional gene-targeting approaches in many experimental organisms incorporated exogenous DNA and/or allele specific sequence that allow for genotyping strategies based on binary readout of PCR product amplification and size selection. In contrast, alleles created by non-homologous end-joining (NHEJ) repair of double-stranded DNA breaks generated by Cas9 are much less amenable to such strategies...
2016: Scientific Reports
Laurence Feldmeyer, Kristine Heidemeyer, Nikhil Yawalkar
Acute generalized exanthematous pustulosis (AGEP) is a severe, usually drug-related reaction, characterized by an acute onset of mainly small non-follicular pustules on an erythematous base and spontaneous resolution usually within two weeks. Systemic involvement occurs in about 20% of cases. The course is mostly benign, and only in rare cases complications lead to life-threatening situations. Recent studies highlight the importance of genetic variations in interleukin-36 receptor antagonist gene (IL-36RN) in the pathogenesis of this disease...
2016: International Journal of Molecular Sciences
Thomas D Curtis, Lone Gram, Gitte M Knudsen
Small Colony Variant (SCV) cells of bacteria are a slow-growing phenotype that result from specific defects in the electron transport chain. They form pinpoint colonies on agar plates and have a variety of phenotypic characteristics, such as altered carbon metabolism, decreased toxin and lytic enzyme production, aminoglycoside resistance, and increased intracellular persistence. They are clinically relevant in Staphylococcus aureus and Pseudomonas aeruginosa, serving as a reservoir for recurrent or prolonged infections...
2016: Frontiers in Microbiology
Nagehan Pakasticali, Gamze Kaya, Unal Senel, Oner Kipritci, Zeynep Tamay, Nermin Guler, Hasan Nazik, Betigul Ongen
Staphylococcus aureus is the most common pathogen isolated from respiratory tract samples in cystic fibrosis (CF) cases. Rate of infection with S. aureus small-colony variants (SCVs) also is increasing in CF patients. In this study, we aimed to determine the prevalence, antibiotic susceptibility and genotypic property of S. aureus SCVs in respiratory tract samples of CF patients admitted to Istanbul Faculty of Medicine Hospital, Turkey. Among 305 respiratory tract samples from 84 CF patients, normal S. aureus isolates were present in 71% of the CF patients and S...
May 2016: Southeast Asian Journal of Tropical Medicine and Public Health
Victor Santos, Irvin Hirshfield
Small colony variants (SCVs) can be defined as a naturally occurring sub-population of bacteria characterized by their reduced colony size and distinct biochemical properties. SCVs of Staphylococcus aureus have been studied extensively over the past two decades due to their role in recurrent human infections. However, little work has been done on SCVs of Escherichia coli, and this work has focused on the physiology and morphology that define these colonies of E. coli, such as small size and slow growth. E. coli strain JW0623, has a null lipA mutation in the lipoic acid synthase gene (lipA), and is a lipoic acid auxotroph...
2016: PloS One
Joe S Matarlo, Yang Lu, Fereidoon Daryaee, Taraneh Daryaee, Bela Ruzsicska, Stephen G Walker, Peter J Tonge
4-Oxo-4-phenyl-but-2-enoates inhibit MenB, the 1,4-dihydroxyl-2-naphthoyl-CoA synthase in the bacterial menaquinone (MK) biosynthesis pathway, through the formation of an adduct with coenzyme A (CoA). Here, we show that the corresponding methyl butenoates have MIC values as low as 0.35-0.75 µg/mL against drug sensitive and resistant strains of Staphylococcus aureus. Mode of action studies on the most potent compound, methyl 4-(4-chlorophenyl)-4-oxobut-2-enoate (1), reveal that 1 is converted into the corresponding CoA adduct in S...
May 13, 2016: ACS Infectious Diseases
Wanli Li, Yinghui Li, Yarong Wu, Yujun Cui, Yao Liu, Xiaolu Shi, Qian Zhang, Qiongcheng Chen, Qun Sun, Qinghua Hu
BACKGROUND: Small colony variants (SCVs), constituting a slow-growing subpopulation of bacteria that facilitates persistence in lethal environmental conditions, are able to revert to the phenotype of rapid growth for further proliferation and transmission. Salmonella enterica serotype Typhimurium is one of the most important foodborne pathogens. This study investigated the genetic mechanisms how SCVs induced by streptomycin reverted to the fast-growing phenotype and the phenotypic changes of SCVs among their complete life cycle in S...
2016: Annals of Clinical Microbiology and Antimicrobials
Nicholas W V Churton, Raju V Misra, Robert P Howlin, Raymond N Allan, Johanna Jefferies, Saul N Faust, Saheer E Gharbia, Richard J Edwards, Stuart C Clarke, Jeremy S Webb
Streptococcus pneumoniae is a commensal human pathogen and the causative agent of various invasive and noninvasive diseases. Carriage of the pneumococcus in the nasopharynx is thought to be mediated by biofilm formation, an environment where isogenic populations frequently give rise to morphological colony variants, including small colony variant (SCV) phenotypes. We employed metabolic characterization and whole-genome sequencing of biofilm-derived S. pneumoniae serotype 22F pneumococcal SCVs to investigate diversification during biofilm formation...
2016: Genome Biology and Evolution
N G Loiko, A N Kozlova, Yu A Nikolaev, A M Gaponov, A V Tutel'yan, G I El'-Registan
Effect of sublethal doses of physical and chemical stressors (heat shock for 2 h at 45 degrees C and addition of C12-alkylhydroxybenzene, a microbial alarmone) on development of resistance to the subsequent lethal antibiotic attack and the role of the time interval between these treatments were studied on a submerged batch culture of Escherichia coli 12. The interval sufficient for the development of stress response provides for development of temporary adaptive resistance to the antibiotic attack, resulting in increased number of surviving persister cells...
September 2015: Mikrobiologiia
Ana Silva, Ana Margarida Sousa, Diana Alves, Anália Lourenço, Maria Olívia Pereira
The emergence of Klebsiella pneumoniae multidrug-resistant strains paves the way to the re-introduction of colistin as a salvage therapy. However, recent planktonic studies have reported several cases of heteroresistance to this antimicrobial agent. The aim of this present work was to gain better understanding about the response of K. pneumoniae biofilms to colistin antibiotherapy and inspect the occurrence of heteroresistance in biofilm-derived cells. Biofilm formation and its susceptibility to colistin were evaluated through the determination of biofilm-cells viability...
July 2016: Pathogens and Disease
Shinji Ogihara, Ryoichi Saito, Etsuko Sawabe, Michio Hagihara, Shuji Tohda
A male patient was admitted to our hospital due to infectious endocarditis. He had been treated with levofloxacin for 6 weeks, sulbactam/cefoperazone for 4 weeks, and benzylpenicillin for 2 days prior to valve replacement surgery. Gram-positive cocci, with morphology consistent with γ-Streptococcus, were detected in blood cultures obtained at admission, as well as in vegetation obtained from the aortic valve. However, the strain could not be identified using biochemical methods. Sequencing of the 16S rRNA gene indicated that the culture was a small-colony variant of Enterococcus faecalis...
October 2016: Journal of Infection and Chemotherapy: Official Journal of the Japan Society of Chemotherapy
Li-li Zhu, Feng-cai Zou, Yu-lin Yan, Qi-hui Wang, Yong-qiang Shi, Wei-jie Qu
Staphylococcus aureus is a major causative agent leading to bovine mastitis and has specific phonotypical characteristics including small colony, slow growth, and decreased hemolysis, therefore named as the small colony variants (SCVs). Out of 30 tested samples of the chronic S. aureus cases, one strain of SCVs (S. aureus SCV22) was isolated along with its parental strains (S. aureus11). S. aureus SCV22 showed a slow growth rate when it is compared with the parental strain. However, their resistant patterns were similar...
2016: TheScientificWorldJournal
Server Yagci, Banu Sancak, Gulsen Hascelik
Staphylococcus aureus small colony variants (SCVs) are associated with chronic and persistent infections. Methicillin-resistant S. aureus (MRSA) SCVs cause more severe infections and mortality rates are higher in comparison with infections caused by MRSA. Our objective was to document the prevalence and phenotypical characteristics of SCVs among MRSA blood isolates. MRSA strains isolated from blood during 1999-2009 were evaluated retrospectively. Among 299 MRSA isolates, suspected colonies were inoculated onto Columbia blood agar and Schaedler agar...
April 8, 2016: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
Wee S Lim, Kevin K S Phang, Andy H-M Tan, Sam F-Y Li, Dave S-W Ow
Phage therapy involves the application of lytic bacteriophages for treatment of clinical infections but bacterial resistance may develop over time. Isolated from nosocomial infections, small colony variants (SCVs) are morphologically distinct, highly virulent bacterial strains that are resistant to conventional antibiotics. In this study, SCVs was derived from Pseudomonas aeruginosa exposed to the lytic bacteriophage PB1 and these cells were resistant to subsequent phage infection by PB1. To elucidate the mechanism of the SCV phage resistance, we performed phenotypic assays, DNA microarrays and whole-genome sequencing...
2016: Frontiers in Microbiology
Nak-Hyun Kim, Yu Min Kang, Woong Dae Han, Kyoung Un Park, Kay-Hyun Park, Jae Il Yoo, Dong-Gun Lee, Chulmin Park, Kyoung-Ho Song, Eu Suk Kim, Sang Won Park, Nam Joong Kim, Myoung-Don Oh, Hong Bin Kim
The small-colony variant (SCV) phenotype of Staphylococcus aureus is associated with intracellular persistence and reduced antimicrobial susceptibility, which can lead to therapeutic failure. Since SCVs grow slowly and have a confusing morphology, the identification of infections due to SCV is difficult. We have identified SCVs in two patients who presented with persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia complicated by surgical site infections after cardiothoracic surgery. Nine blood isolates were collected from the two patients for species identification, antimicrobial susceptibility testing, and phenotypic and genotypic characterization...
March 16, 2016: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
Jia-Xiang See, Chandramathi Samudi, Alireza Saeidi, Nivedita Menon, Leang-Chung Choh, Jamuna Vadivelu, Esaki M Shankar
BACKGROUND: Burkholderia pseudomallei (B. pseudomallei), the causative agent of melioidosis, is a deadly pathogen endemic across parts of tropical South East Asia and Northern Australia. B. pseudomallei can remain latent within the intracellular compartment of the host cell over prolonged periods of time, and cause persistent disease leading to treatment difficulties. Understanding the immunological mechanisms behind persistent infection can result in improved treatment strategies in clinical melioidosis...
March 2016: PLoS Neglected Tropical Diseases
Yu-Tzu Lin, Jui-Chang Tsai, Tatsuo Yamamoto, Hsiao-Jan Chen, Wei-Chun Hung, Po-Ren Hsueh, Lee-Jene Teng
OBJECTIVES: Small colony variants (SCVs) of Staphylococcus aureus are associated with persistent and drug-resistant infections. We demonstrated for the first time the emergence of SCVs in a patient with vancomycin-intermediate S. aureus (VISA) infection during long-term treatment with daptomycin. METHODS: A 73-year-old man with septic arthritis was infected with VISA. The patient was treated with daptomycin; however, the patient remained infected with VISA, with continuous isolation of VISA from his blood during long-term treatment...
July 2016: Journal of Antimicrobial Chemotherapy
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