Mycoplasma

11 Key excerpts on "Mycoplasma"

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  Antimicrobial Resistance in Bacteria from Livestock and Companion Animals

  • Frank M. Aarestrup, Stefan Schwarz, Lina Maria Cavaco, Jianzhong Shen, Stefan Schwarz, Lina Maria Cavaco, Jianzhong Shen(Authors)
  • 2018(Publication Date)
  • ASM Press

    (Publisher)

  20 Antimicrobial Resistance in Mycoplasma spp.

  Anne V. Gautier-Bouchardon1

  INTRODUCTION

  Mycoplasmas belong to the phylum Firmicutes (Gram-positive bacteria with low G+C content), to the class Mollicutes (from Latin: mollis , soft; cutis , skin), to the order Mycoplasmatales , and to the family Mycoplasmataceae . They presumably evolved by degenerative evolution from Gram-positive bacteria and are phylogenetically most closely related to some clostridia. Mycoplasmas are the smallest self-replicating prokaryotes (diameter of approximately 0.2 to 0.3 μm) with the smallest genomes (500 to 1,000 genes). They are characterized by the lack of a cell wall. The Mycoplasma cell contains the minimum set of organelles essential for growth and replication: a plasma membrane, ribosomes, and a genome consisting of a double-stranded circular DNA molecule (1 ). The Mycoplasma genome is characterized by a low G+C content and by the use of the universal stop codon UGA as a tryptophan codon. As a result of their limited genetic information, Mycoplasmas express a small number of cell proteins and lack many enzymatic activities and metabolic pathways (1 ). Their nutritional requirements are therefore complex, and they are dependent on their host for many nutrients. This phenomenon explains the great difficulty of in vitro cultivation of Mycoplasmas, with complex media containing serum (as a source of fatty acids and cholesterol) and a metabolizable carbohydrate (as a source of energy, for example, glucose, arginine, or urea).

  All Mycoplasmas cultivated and identified so far are parasites of humans or animals (2 –5 ), with a high degree of host and tissue specificity. The primary habitats of Mycoplasmas are epithelial surfaces of the respiratory and urogenital tracts, serous membranes, and mammary glands in some animal species. Many Mycoplasma species are pathogens, causing various diseases and significant economic losses in livestock productions. Mycoplasmas have developed mechanisms to resist their hosts’ immune systems: modulatory effects on the host immune system, a highly plastic set of variable surface proteins responsible for rapid changes in major surface protein antigens (6 , 7 ) and invasion of nonphagocytic host cells (8 –11 ). These mechanisms contribute to the persistence of Mycoplasmas in their hosts and to the establishment of chronic infections. The main pathogenic species in humans and animals are listed in Table 1

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  Pathogenesis of Bacterial Infections in Animals

  • Carlton L. Gyles, John F. Prescott, J. Glenn Songer, Charles O. Thoen(Authors)
  • 2008(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  397 29 Mycoplasma K. L. Whithear and G. F. Browning Mycoplasmas are unique, cell-wall-less prokaryotes that are the smallest cells (down to approximately 300 nm diameter) and have the smallest genomes (down to 580 kb) of all free-living organisms. The term “Mycoplasma” is commonly used in the trivial sense to refer to members of the class Mollicutes. They are widely distributed in nature as parasites of mammals, birds, reptiles, fish, arthropods, and plants. Species in the genera Mycoplasma, Ureaplasma, and Acholeplasma may be found in clinical specimens from animals, but most of the animal pathogens are members of the genus Mycoplasma. The hemotrophic pathogens Haemo- bartonella spp. and Eperythrozoon spp., formerly classified as rickettsia, are now considered to be members of the genus Mycoplasma (Neimark et al. 2001). Phylogenetically, Mollicutes are related to gram-positive bacteria with low genomic G + C mol % content (Clostridium, Lactobacillus, Bacillus, and Streptococcus) (Maniloff 1992). CHARACTERISTICS OF THE ORGANISM The small cell and genome sizes of Mycoplasmas reflect fastidious requirements for growth, so that a highly enriched medium is needed to cultivate them in the laboratory. Osmotic stability under physio- logical conditions is maintained by incorporation in the cell membrane of cholesterol (unique among the prokaryotes), which, in all genera except Achole- plasma, must be supplied preformed. In nature, Mycoplasmas are obligate parasites that are well adapted to survive on moist mucosal surfaces of their vertebrate hosts. Although sharing common features, mycoplas- mas are nevertheless a diverse group, particularly with respect to their pathogenic potential, which varies widely both between species and among strains within species. Many species are commen- sals, whereas a few can cause acute mortality. Assessing the pathogenic role of Mycoplasmas can be problematic.

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  Healing Lyme Disease Coinfections

  Complementary and Holistic Treatments for Bartonella and Mycoplasma

  • Stephen Harrod Buhner(Author)
  • 2013(Publication Date)
  • Healing Arts Press

    (Publisher)

  2

  Mycoplasma

  An Overview

  Mycoplasmas are most unusual self-replicating bacteria, possessing very small genomes, lacking cell wall components, requiring cholesterol for membrane function and growth, using UGS codon for tryptophan, passing through “ bacterial-retaining” filters, and displaying genetic economy that requires a strict dependence on the host for nutrients and refuge. In addition, many of the Mycoplasmas pathogenic for humans and animals possess extraordinary specialized tip organelles that mediate their intimate interaction with eucaryotic cells. This host-adapted survival is achieved through surface parasitism of target cells, acquisition of essential biosynthetic precursors, and in some cases, subsequent entry and survival intracellularly. Misconceptions concerning the role of Mycoplasmas in disease pathogenesis can be directly attributed to their biological subtleties and to fundamental deficits in understanding their virulence capabilities.

  JOEL BASEMAN AND JOSEPH TULLY , “MYCOPLASMAS : SOPHISTICATED, REEMERGING, AND BURDENED BY THEIR NOTORIETY ”

  The Mycoplasmas enter an appropriate host in which they multiply and survive for long periods of time. These microorganisms have evolved molecular mechanisms needed to deal with the host immune response and the transfer and colonization in a new host. These mechanisms include mimicry of host antigens, survival within phagocytic and nonphagocytic cells, and generation of phenotypic plasticity.

  SHLOMO ROTTEM , “INTERACTION OF MycoplasmaS WITH HOST CELLS ”

   

  Mycoplasmas are Gram-positive bacteria and they are tiny . In fact, some of them approach in size the smallest genome that has been calculated to be theoretically possible. Such is the case with Mycoplasma genitalium, a common pathogen of human beings. It is the smallest bacterium known.

  To get an idea of just how small: 4,000 Mycoplasma bacteria can fit inside one red blood cell; in comparison, only about 12 bartonella bacteria can. And red blood cells are tiny themselves, only about six to eight micrometers in width (a micrometer is a millionth of a meter). Just pretend a red blood cell is the size of the point of a pin (it is actually smaller), then imagine 4,000 bacteria inside that point. That’s how small Mycoplasmas are.

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  Pathogenesis of Bacterial Infections in Animals

  • John F. Prescott, Janet I. MacInnes, Filip Van Immerseel, John D. Boyce, Andrew N. Rycroft, José A. Vázquez-Boland, John F. Prescott, Janet I. MacInnes, Filip Van Immerseel, John D. Boyce, Andrew N. Rycroft, José A. Vázquez-Boland(Authors)
  • 2022(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  31 Mycoplasmas

  Pollob K. Shil, Nadeeka K. Wawegama, Glenn F. Browning, Amir H. Noormohammadi, and Marc S. Marenda

  Introduction

  All members of the class Mollicutes are commonly referred to as Mycoplasmas. Each of the major domestic animal species is host to several different species of pathogenic Mycoplasmas, which typically cause chronic, endemic disease. Mycoplasmas lack a cell wall and have the smallest cell size (down to approximately 300 nm diameter) and the smallest genomes (down to 580 kb) of all free‐living organisms, a consequence of their reductive evolution from Gram‐positive bacteria with a low genomic G + C mol% content. They have a broad biological distribution as parasites of mammals, birds, reptiles, fish, cephalopods, crustaceans, arthropods, and plants. They are divided into four phylogenetic groups, Pneumoniae, Hominis, Anaeroplasma and Spiroplasma, but exhibit considerable genetic plasticity, with massive horizontal genetic transfer events between species in different phylogenetic groups shaping the evolution of a number of important pathogenic species. This is exemplified by the Mycoides cluster, a group of highly pathogenic species that only infect ruminants but lie within the Spiroplasma group, which is predominantly composed of insect‐transmitted plant pathogens. While the core genomes of the members of this cluster are most closely related to the spiroplasmas, approximately 20% of their genome is most closely related to the genomes of ruminant Mycoplasmas in the Hominis group. One member, Mycoplasma mycoides subspecies mycoides, causes contagious bovine pleuropneumonia (CBPP), one of the most important bacterial diseases of domestic animals.

  Characteristics of the Organisms

  Mycoplasmas are obligate parasites and most survive on moist mucosal surfaces of their vertebrate hosts, although the hemophilic Mycoplasmas are exclusively parasites of erythrocytes. They are highly pleomorphic, but do have a cytoskeleton that controls their shape (Balish and Krause 2006

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  Pathogenic Mycoplasmas

  • Katherine Elliott, Joan Birch, Katherine Elliott, Joan Birch(Authors)
  • 2009(Publication Date)
  • Wiley

    (Publisher)

  In general, the Mycoplasmas are rather inconspicuous predators. They often coexist with their host in a truce that is only occasionally broken, and the diseases they produce are generally chronic and require long incubation periods. One admires them for their cunning ways, which command the admiration of the microbiologist and the respect of the clinician. Their fragility often belies their virulence. As the smallest free-living microorganisms they have enchanted the molecular biologist who sees in them several unique problems. Foremost among these is the question: how can such a small package (150 nm) contain all the genetic information necessary to programme and execute all of life’s basic functions? Since most Mycoplasma species require cholesterol for growth and incorporate it directly into their cell membranes, the membrane physiologist is intrigued with these organisms. The taxonomist is in rather a quandary. If he reasons that because they lack a rigid cell wall, they must be animal forms, then he must contend with the notion that they are prokaryotic and do not have a nuclear membrane, and hence are more properly considered as plants. The Subcommittee on Taxonomy of the Mycoplasmatales has, however, succeeded in removing them as the tenth order in the class Schizomycetes and elevating them to the status of a new class, Mollicutes (Edward & Freundt 1967). Consequently they are still classified as plant forms. 18 L. HAYFLICK TABLE I Ecology of the Mycoplasmas ~ Location Cat Cattle Chicken Dog Duck Goat Guinea pig Hamster Hedgehog Horse Insects Man Mouse Monkey Parakeet Pheasant Pigeon Plants Rabbit Rat Sewage Sheep Soil Swine Tissue culture Turkey ~~~ ~~ Initial reference Cole et al. (1967) Nocard et al. (1898) Nelson (1935) Shoetensack (1934) Barber & Fabricant (1971) Bridre & Donatien (1923) Klieneberger (1935) Ito (1960) Tan et al. (1971) Beller (1944) Carrere (1952) Dienes & Edsall (1937) Nelson (1935) Taylor-Robinson et al.

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  Molecular Detection of Human Bacterial Pathogens

  • Dongyou Liu(Author)
  • 2011(Publication Date)
  • CRC Press

    (Publisher)

  455 41.1 INTRODUCTION Mycoplasmas (class Mollicutes) are the self-replicating, smallestfree-livingbacteriaintermsofbothcellulardimen-sions and genome size that are capable of a cell-free exis-tence 1 Theyareuniqueamongbacteriabecausetheydiffer from the other common bacteria having their minute size, lackofcellwall,andabilitytopassthroughfilterswithpore sizesthatretainotherbacteriaandthatwereearlierthought tobeviruses 2,3 Buttheirdifferencefromviruseswasreali-zedbyfindingbothRNAandDNAinthemandtheirability togrowincell-freemedia(Table411) ThesmallestMycoplasmasare01–03µminsizeThey are highly pleomorphic because they lack a rigid cell wall andinsteadareboundedbyatriple-layered“unitmembrane” thatcontainssterolsTheyrequiresterolasakeyrequirement fortheirgrowth,whichisnotacomponentofthebacterial cellorvirusesSterolsprovidesomestructuralsupporttothe osmoticallyfragileMycoplasmasastheyarelackinginthe capacitytosynthesizecellwallpeptidoglycanoritsprecur-sors 4 Thelackofpeptidoglycanmakestheminherentlyresis-tanttobeta-lactamantibiotics 5 41.1.1 C LASSIFICATION , M ORPHOLOGY , AND B IOLOGY Classification.

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  Methods in Mycoplasmology V1

  Mycoplasma Characterization

  • Samuel Razin(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  Moreover, the L-phase variants, unlike Mycoplasmas, are capable of synthesizing precursors of bacterial cell wall polymers and penicillin-binding proteins (Martin etal., 1980). The lack of a cell wall constitutes the basis for the inclusion of the my-coplasmas in a separate class: Mollicutes (mollis, soft; cutis, skin). The common term Mycoplasmas has been used rather loosely to denote any species in the class Mollicutes, whereas the terms acholeplasmas, ureaplasmas, spiroplasmas , and anaeroplasmas are used when reference is made to members of the correspond-3 METHODS IN MYCOPLASMOLOGY, VOL. I Copyright © 1983 by Academic Press, Inc. All rights of reproduction in any form reserved. ISBN 0-12-583801-8 4 Shmuel Razin ing genus, rather than to a defined species within the genus. The term mollicutes has been proposed as a common name for any member of the class. In this case, the common name Mycoplasmas will be retained for Mycoplasma species only. The principles of Mycoplasma classification and taxonomy are discussed in Chapter A2 in this volume. The Mycoplasmas are the smallest self-replicating prokaryotes. Mycoplasma cultures contain coccoid cells that have diameters as small as 300 nm and are still capable of reproduction. Moreover, Mycoplasmas usually exhibit an extremely simple ultrastructure. The Mycoplasma cell is bounded by a plasma membrane, and the enclosed cytoplasm contains ribosomes and a circular double-stranded DNA molecule. A fibrillar network, probably representing a primitive cytoskeleton and participating in contractile processes and shape formation, has been demonstrated in a few mollicutes but may be a common feature of these plastic microorganisms. In some Mycoplasmas unique polar organelles shaped as tapered tips or blebs built around a central striated rod have been observed.

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  Diagnostic Procedure in Veterinary Bacteriology and Mycology

  • Grace R. Carter, John R. Cole Jr., John R. Cole, Jr.(Authors)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  Unlike bacteria, they have no cell wall but are bounded by a membrane. This explains their remarkable pleomorphism. In stained smears, they are seen as ring forms, globules, small coccobacilli, of filaments. Although the “fried egg” colony is the hallmark, a high percentage grow with aberrant colonial morphology when first isolated or grow as tiny colonies (T Mycoplasmas or ureaplasmas) visible only under the low power microscope (Fig. 27-1). Because most Mycoplasmas require sterol for growth, suggestions were made that they be placed in the animal kingdom, but the current tendency is to place them into a sixth division of microbiology as distinct from bacteria, viruses, fungi, protozoa, and the blue-green algae. The nonsterol-requiring organisms are known as acholeplasmas, whereas the family Mycoplasmataceae contains five genera, including pathogens of humans, animals, plants, and insects, and parasitic or free-living Mycoplasmas of such diverse environments as the intestine and rumen of the cow, hot springs, and the waters of abandoned coal mines. Figure 27-1 Mycoplasmal colonial morphology. A, unidentified isolate from eye of a sick goat; B, unidentified isolate from aborted bovine fetus; C and D, Mycoplasma bovis, showing small colonies without halos, and granular colonies, recovered from experimentally infected cows (× 40); E, ureaplasma from bull semen (× 200). The class Mollicutes (Table 27-1) contains more than forty pathogens of humans and animals including the causative agents of three respiratory diseases formerly thought to be due to viruses: primary atypical (virus) pneumonia of humans (Mycoplasma pneumoniae); Mycoplasmal (virus) pneumonia of swine (M. hyopneumoniae), and bovine contagious pleuropneumonia (M. mycoides subsp. mycoides). Mycoplasmas are mostly host-specific but M. bovis, for example, which causes a variety of lesions in cattle, has been isolated from the lungs of pneumonic sheep and from human patients with respiratory disease

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  Biomedical Tissue Culture

  • Luca Ceccherini-Nelli, Barbara Matteoli, Luca Ceccherini-Nelli, Barbara Matteoli(Authors)
  • 2012(Publication Date)
  • IntechOpen

    (Publisher)

  Mycoplasmas are spread by using laboratory equipment, media, or reagents that have been contaminated by previous use in processing Mycoplasma-infected cell cultures. New cell-culture acquisitions should be quarantined, tested and guaranteed Mycoplasma-free before introduction into the tissue-culture laboratory. Common experimental stock materials, such as virus pools, or monoclonal antibody preparations, can also be a key source of Mycoplasma contamination. As there is no legal requirement for suppliers to provide Mycoplasma-free products, bovine serum should be considered as a possible source of contamination. Mycoplasma contaminants of bovine serum are primarily bovine species, with A. laidlawii and M. arginini being isolated most frequently [5]. Contamination of Tissue Cultures by Mycoplasmas 37 3. Mode of interaction with host cells 3.1. Adherence to host cells Most Mycoplasmas are typical extracellular microorganisms able to adhere to the surface of tissue culture cells. Many Mycoplasmas exhibit the typical polymorphism of Mycoplasmas, with the most common filamentous, flask shapes or ovoid structures (Figure 1, Ref. 6). The adherence of Mycoplasmas to host cells is an initial and essential step in tissue colonization [4]. The lack of a cell wall has forced Mycoplasmas to develop sophisticated molecular mechanisms to enable their prolonged adhesion. Adherence is associated with adhesins as well as host cell receptors that mediate interaction of the bacteria with the host cells [7]. Figure 1. Transmission electron microscopy of M. hyorhinis (A) and of a melanoma cell culture infected by M. hyorhinis (B). Flask shaped bacteria in close proximity to melanoma cells are indicated by arrows. A polar, tapered cell extension at one of the poles containing an electron-dense core in the cytoplasma was described in some Mycoplasmas (Figure 2). This structure, termed the tip organelle, functions mainly as an attachment and motility organelle.

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  Polymerase Chain Reaction

  • Patricia Hernandez-Rodriguez, Arlen Patricia Ramirez Gomez, Patricia Hernandez-Rodriguez, Arlen Patricia Ramirez Gomez(Authors)
  • 2012(Publication Date)
  • IntechOpen

    (Publisher)

  In: Mycoplasmas: Molecular biology and Pathogenesis , J. Maniloff, R.N. McElhaney, L.R. Finch , & J.B. Baseman (Eds.), pp. 549-559, American Society for Microbiology, ISBN 1-55581-050-0, U.S.A. Mendoza N., Ravanfar, P., Shetty, A.K., Pellicane, B.L., Creed, R., Goel, S., & Tyring, S.K. (2011). Genital Mycoplasma Infection, In: Sexually Transmitted Infections and Sexually Transmitted Diseases , G. Gross, & S.K. Tyring (Eds.), 197-201, Springer-Verlag, ISBN 978-3-642-14663-3, Heidelberg, Berlin Mothershed, E.A., & Whitney, A.M. (2006). Nucleic Acid-Based Methods for the Detection of Bacterial Pathogens: Present and Future Considerations for the Clinical Laboratory. Clinica Chimica Acta , Vol. 363, No. 1-2, (January 2006), pp. 206–220, ISSN 0009-8981 Noussair L, Bert F, Leflon-Guibout V, Gayet N, Nicolas-Chanoine MH. (2009) Early Diagnosis of Extrapulmonary Tuberculosis by a New Procedure Combining Broth Culture and PCR. Journal of Clinical Microbiology , Vol. 47, No. 5 (May 2009), pp. 1452-1457, ISSN 0095-1137 Palmer, H.M., Gilroy, C.B., Furr, P.M., & Taylor-Robinson, D. (1991). Development and Evaluation of the Polymerase Chain Reaction to Detect Mycoplasma genitalium . FEMS Microbiology Letters , Vol. 77, No. 2-3, (January 1991), pp. 199-204. ISSN 0378-1097 Patel, M.A., & Nyirjesy, P. (2010). Role of Mycoplasma and Ureaplasma Species in Female Lower Genital Tract Infections. Current Infectious Diseases Report , Vol. 12, No. 6, (November 2010), pp. 417–422, ISSN 1523-3847 Povlsen, K,. Thorsen, P., & Lind, I. (2001). Relationship of Ureaplasma urealyticum Biovars to the Presence or Absence of Bacterial Vaginosis in Pregnant Women and to the Time of Delivery. European Journal of Clinical Microbiology and Infectious Diseases , Vol. 20, No. 1, (January 2001), pp. 65-67, ISSN 0934-9723 Povlsen, K., Bjørnelius, E., Lidbrink, P., & Lind, I. (2002). Relationship of Ureaplasma urealyticum Biovar 2 to Nongonococcal Urethritis.

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  The Mycoplasmas V2

  Human and Animal Mycoplasmas

  • J Tully(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  However, fulfillment of Koch's postulates in conventionally reared animals becomes less meaningful when the organism concerned is less pathogenic, and especially when its significance may only be expressed fully in association with some other organism or organisms. Most pathogenic Mycoplasmas fall into this cate-gory. In this case, to determine the exact role of a Mycoplasma in the disease process, it is necessary to employ specific-pathogen-free, gnotobiotic, or germ-free animals. This is additionally important in studies on genital or respiratory disease, as many apparently normal animals suffer from subclinical infections. Apart from the fulfillment of Koch's postulates, other evidence of pathogenicity or pathogenic potential may be of value in assessing the role of a Mycoplasma in a disease situation. Such evidence can be the ability to cause damage to any tissue, either m vivo or in vitro, such as damage after inoculation at another anatomical site such as the mammary gland, or the inoculation of tissue or organ cultures. Certain biophysical or biochemical characteristics of the Mycoplasma may be suggestive of pathogenic poten-tial, such as the production of a toxin or the presence of a capsule or a terminal attachment structure. Incidentally, production of antibody by the animal inoculated with a particular organism does not necessarily imply etiological significance; the organism may simply be multiplying in the disease tissue. Table II lists the different anatomical sites from which the named species and recognized serotypes of bovine Mycoplasmas have been isolated (under nonbacteremic situations) and also summarizes our views on the pathogenic status of these species at these sites. However, the virulence of strains within a species is not constant, and avirulent strains can exist within a pathogenic species.

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