DOCSLIB.ORG

Moraxella Catarrhalis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Moraxella Catarrhalis 48 Monte Carlo Crescent Kyalami Business Park, Kyalami Johannesburg, 1684 South Africa www.thistle.co.za Tel: +27 (011) 463 3260 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] Please read this section first The HPCSA and the Med Tech Society have confirmed that this clinical case study, plus your routine review of your EQA reports from Thistle QA, should be documented as a “Journal Club” activity. This means that you must record those attending for CEU purposes. Thistle will not issue a certificate to cover these activities, nor send out “correct” answers to the CEU questions at the end of this case study. The Thistle QA CEU No is: MTS-18/063. Each attendee should claim ONE CEU point for completing this Quality Control Journal Club exercise, and retain a copy of the relevant Thistle QA Participation Certificate as proof of registration on a Thistle QA EQA. MICROBIOLOGY LEGEND CYCLE 44 ORGANISM 1 Moraxella catarrhalis Moraxella catarrhalis is a fastidious, nonmotile, Gram-negative, aerobic, oxidase-positive diplococcus that can cause infections of the respiratory system, middle ear, eye, central nervous system, and joints of humans. It causes the infection of the host cell by sticking to the host cell using trimeric autotransporter adhesins. M. catarrhalis was previously placed in a separate genus named Branhamella. The rationale for this was that other members of the genus Moraxella are rod-shaped and rarely caused infections in humans. However, results from DNA hybridization studies and 16S rRNA sequence comparisons were used to justify inclusion of the species M. catarrhalis in the genus Moraxella. As a consequence, the name Moraxella catarrhalis is currently preferred for these bacteria. Nevertheless, some in the medical field continue to call these bacteria Branhamella catarrhalis. Clinical significance These bacteria are known to cause otitis media, bronchitis, sinusitis, and laryngitis. Elderly patients and long-term heavy smokers with chronic pulmonary disease should be aware that M. catarrhalis is associated with bronchopneumonia, as well as exacerbations of existing chronic obstructive pulmonary disease (COPD). The peak rate of colonisation by M. catarrhalis appears to occur at approximately 2 years of age, with a striking difference in colonization rates between children and adults (very high to very low). M. catarrhalis has recently been gaining attention as an emerging human pathogen. It has been identified as an important cause in broncho-pulmonary infection, causing infection through pulmonary aspiration in the upper pulmonary tract. Additionally, it causes bacterial pneumonia, especially in adults with a compromised immune system. It has also been known to cause infective exacerbations in adults with chronic lung disease, and it is an important cause in acute sinusitis, maxillary sinusitis, bacteremia, meningitis, conjunctivitis, acute purulent irritation of chronic bronchitis, urethritis, septicaemia (although this is rare), septic arthritis (which is also a rare occurrence), as well as acute laryngitis in adults and acute otitis media in children. M. catarrhalis is an opportunistic pulmonary invader, and causes harm especially in patients who have compromised immune systems or any underlying chronic disease. Page 1 of 3 48 Monte Carlo Crescent Kyalami Business Park, Kyalami Johannesburg, 1684 South Africa www.thistle.co.za Tel: +27 (011) 463 3260 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] Figure 1: Antibiotic sensitivity test: This strain shows resistance to ampicillin because it produces the enzyme β-lactamase. This is confirmed by the disc labelled β turning red Treatment M. catarrhalis can be treated with antibiotics, but it is commonly resistant to penicillin, ampicillin, and amoxicillin. Treatment options include antibiotic therapy or a so-called "watchful waiting" approach. The great majority of clinical isolates of this organism produce beta-lactamases and are resistant to penicillin. Resistance to trimethoprim, trimethoprim- sulfamethoxazole (TMP-SMX), clindamycin, and tetracycline have been reported. It is susceptible to fluoroquinolones, most second and third generation cephalosporins, erythromycin, and amoxicillin-clavulanate. Adults can also take tetracycline and fluoroquinolone antibiotics. Prognosis The prognosis of M. catarrhalis infection is poor in hospitalized patients with underlying conditions, especially the following: Patients hospitalized for prolonged periods Patients in pulmonary units or paediatric intensive care units Patients of advanced age The most significant infections caused by M. catarrhalis are upper respiratory tract infections (URTIs) such as otitis media and sinusitis in children and lower respiratory tract infections (LRTIs) in adults. Infections with M. catarrhalis in adults are more common if underlying conditions are present, especially if the patient is elderly. Risk Factors Persons with chronic obstructive pulmonary disease (COPD), chronic bronchitis, or bronchiectasis are generally more susceptible to infection, as well as those with acquired immunodeficiency disease. Additionally, those who work in cold weather are generally at a higher risk. Prevention Because of the high colonization rate and lack of vaccine, it is very difficult to completely prevent infections. Proper hygiene such as hand washing is useful in deterring infection. However, this can be very nearly impossible in young children as many will develop otitis media, however not necessarily from M. catarrhalis. Page 2 of 3 48 Monte Carlo Crescent Kyalami Business Park, Kyalami Johannesburg, 1684 South Africa www.thistle.co.za Tel: +27 (011) 463 3260 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] References 1. http://emedicine.medscape.com/article/222320 2. http://en.wikipedia.org/wiki/Moraxella_catarrhalis 3. https://microbewiki.kenyon.edu/index.php/Moraxella_catarrhalis_pathogenesis Questions 1. Discuss the morphological characteristics of M. catarrhalis. 2. Discuss the prognosis of M. catarrhalis. 3. Discuss the clinical significance of M. catarrhalis. Page 3 of 3 .
Load more

Recommended publications
  • Biofilm Formation by Moraxella Catarrhalis
    BIOFILM FORMATION BY MORAXELLA CATARRHALIS APPROVED BY SUPERVISORY COMMITTEE Eric J. Hansen, Ph.D. ___________________________ Kevin S. McIver, Ph.D. ___________________________ Michael V. Norgard, Ph.D. ___________________________ Philip J. Thomas, Ph.D. ___________________________ Nicolai S.C. van Oers, Ph.D. ___________________________ BIOFILM FORMATION BY MORAXELLA CATARRHALIS by MELANIE MICHELLE PEARSON DISSERTATION Presented to the Faculty of the Graduate School of Biomedical Sciences The University of Texas Southwestern Medical Center at Dallas In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY The University of Texas Southwestern Medical Center at Dallas Dallas, Texas March, 2004 Copyright by Melanie Michelle Pearson 2004 All Rights Reserved Acknowledgements As with any grand endeavor, there was a large supporting cast who guided me through the completion of my Ph.D. First and foremost, I would like to thank my mentor, Dr. Eric Hansen, for granting me the independence to pursue my ideas while helping me shape my work into a coherent story. I have seen that the time involved in supervising a graduate student is tremendous, and I am grateful for his advice and support. The members of my graduate committee (Drs. Michael Norgard, Kevin McIver, Phil Thomas, and Nicolai van Oers) have likewise given me a considerable investment of time and intellect. Many of the faculty, postdocs, students and staff of the Microbiology department have added to my education and made my experience here positive. Many members of the Hansen laboratory contributed to my work. Dr. Eric Lafontaine gave me my first introduction to M. catarrhalis. I hope I have learned from his example of patience, good nature, and hard work.
    [Show full text]
  • Neisseria Acinetobacter, Moraxella ? and Kingella Based on Partial 16S Ribosomal DNA Sequence Analysis4
    INTERNATIONALJOURNAL OF SYSTEMATICBACTERIOLOGY, July 1994, p. 387-391 Vol. 44, No. 3 0020-7713/94/$04.00 + 0 Copyright 0 1994, International Union of Microbiological Societies Phylogenetic Relationships between Some Members of the Genera Neisseria Acinetobacter, Moraxella ? and Kingella Based on Partial 16s Ribosomal DNA Sequence Analysis4. M. C. ENRIGHT,” P. E. CARTER, I. A. MACLEAN,AND H. McKENZIE Department of Medical Microbiology, Faculty of Medicine, University of Aberdeen, Foresterhill, Aberdeen, Scotland AB9 220 We obtained 16s ribosomal DNA (rDNA) sequence data for strains belonging to 11 species of Proteobacteria, including the type strains of Kingella kingae, Neisseria lactamica, Neisseria meningitidis, Moraxella lacunata subsp. lacunata, [Neisseria] ovis, Moraxella catarrhalis, Moraxella osloensis, [Moraxella] phenylpyruvica, and Acineto- bacter lwo$i, as well as strains of Neisseria subflava and Acinetobacter calcoaceticus. The data in a distance matrix constructed by comparing the sequences supported the proposal that the genera Acinetobacter and Moraxella and [N.] ovis should be excluded from the family Neisseriaceae. Our results are consistent with hybridization data which suggest that these excluded taxa should be part of a new family, the Moraxellaceae. The strains that we studied can be divided into the following five groups: (i) M. lacunata subsp. lacunata, [N.] ovis, and M. catarrhalis; (ii) M. osloensis; (iii) [M.]phenylpyruvica; (iv) A. calcoaceticus and A. lwofii; and (v) N. meningitidis, N. subflava, N. lactamica, and K. kingae. We agree with the previous proposal that [N.] ovis should be renamed Moraxella ovis, as this organism is closely related to Moraxella species and not to Neisseria species. The generically misnamed taxon [M.] phenylpyruvica belongs to the proposed family Moraxellaceae, but it is sufficiently different to warrant exclusion from the genus Moraxella.
    [Show full text]
  • Cave-73-02-Fullr.Pdf
    EDITORIAL Production Changes for Future Publication of the Journal of Cave and Karst Studies SCOTT ENGEL Production Editor The Journal of Cave and Karst Studies has experienced December 2011 issue, printed copies of the Journal will be budget shortfalls for the last several years for a multitude automatically distributed to paid subscribers, institutions, of reasons that include, but are not limited to, increased and only those NSS members with active Life and cost of paper, increased costs of shipping through the Sustaining level memberships. The remainder of the NSS United State Postal Service, increased submissions, and membership will be able to view the Journal electronically stagnant funding from the National Speleological Society online but will not automatically receive a printed copy. Full (NSS). The cost to produce the Journal has increased 5 to content of each issue of the Journal will be available for 20 percent per year for the last five years, yet the budget for viewing and downloading in PDF format at no cost from the the Journal has remained unchanged. To offset rising costs, Journal website www.caves.org/pub/journal. the Journal has implemented numerous changes over recent Anyone wishing to receive a printed copy of the Journal years to streamline the production and printing process. will be able to subscribe for an additional cost separate However, the increasing production costs, combined with from normal NSS dues. The cost and subscription process the increasing rate of good-quality submissions, has were still being determined at the time of this printing. resulted in the number of accepted manuscripts by the Once determined, the subscription information will be Journal growing faster than the acquisition of funding to posted on the Journal website.
    [Show full text]
  • Helicobacter Pylori Outer Membrane Vesicles and the Host-Pathogen Interaction
    Helicobacter pylori outer membrane vesicles and the host-pathogen interaction Annelie Olofsson Department of Medical Biochemistry and Biophysics Umeå 2013 Responsible publisher under swedish law: the Dean of the Medical Faculty This work is protected by the Swedish Copyright Legislation (Act 1960:729) ISBN: 978-91-7459-578-9 ISSN: 0346-6612 New series nr: 1559 Cover: Electron micrograph of outer membrane vesicles Elektronisk version tillgänglig på http://umu.diva-portal.org/ Printed by: VMC-KBC, Umeå University Umeå, Sweden, 2013 Till min mormor och farfar i ii INDEX ABSTRACT iv LIST OF PAPERS v SAMMANFATTNING vi ABBREVIATIONS viii INTRODUCTION 1 BACKGROUND 2 The human stomach 2 Helicobacter pylori 3 Epidemiology 3 Gastric diseases 3 Clinical outcome 4 Treatment and disease determinants 5 The gastric environment and host cell responses 6 H. pylori colonization and virulence factors 8 cagPAI 9 CagA and apical junctions 11 The H. pylori outer membrane 12 Phospholipids and cholesterol 12 Lipopolysaccharides 13 Outer membrane proteins 14 Adhesins and their cognate receptor structures 14 Bacterial outer membrane vesicles 15 Vesicle biogenesis and composition 15 Biological consequences of vesicle shedding 18 Endocytosis and uptake of bacterial vesicles 19 Clathrin-mediated endocytosis 20 Clathrin-independent endocytosis 21 Caveolae 22 Modulation of host cell defenses and responses 23 AIM OF THESIS 24 RESULTS AND DISCUSSION 25 Paper I 25 Paper II 27 Paper III 28 Paper IV 31 CONCLUDING REMARKS 34 ACKNOWLEDGEMENTS 36 REFERENCES 38 iii ABSTRACT The gastric pathogen Helicobacter pylori chronically infects the stomachs of more than half of the world’s population. Even though the majority of infected individuals remain asymptomatic, 10–20% develop peptic ulcer disease and 1–2% develop gastric cancer.
    [Show full text]
  • Moraxella Species: Infectious Microbes Identified by Use of Time-Of
    Japanese Journal of Ophthalmology (2019) 63:328–336 https://doi.org/10.1007/s10384-019-00669-4 CLINICAL INVESTIGATION Moraxella species: infectious microbes identifed by use of time‑of‑fight mass spectrometry Shunsuke Takahashi1 · Kazuhiro Murata1 · Kenji Ozawa1 · Hiroki Yamada2 · Hideaki Kawakami3 · Asami Nakayama4 · Yuko Asano5 · Kiyofumi Mochizuki1 · Hiroshige Mikamo6 Received: 14 August 2018 / Accepted: 2 April 2019 / Published online: 4 July 2019 © Japanese Ophthalmological Society 2019 Abstract Purpose To report the clinical manifestations, identifcation, antimicrobial susceptibilities, and treatment outcomes of ocular infections caused by Moraxella species. Study design Retrospective study. Patients and methods The medical records of all patients treated at the Departments of Ophthalmology of the Ogaki Munici- pal Hospital and the Gifu University Graduate School of Medicine for ocular infections caused by Moraxella species between January 2011 and June 2017 were examined. The stored Moraxella species isolated from ocular samples were identifed by matrix-assisted laser desorption/ionization time-of-fight mass spectrometry (MALDI-TOF MS), molecular identifcation, and the biochemical properties. Results Sixteen eyes of 16 patients were treated for Moraxella ocular infections. The patients’ median age was 72 years. A predisposing systemic or ocular condition was identifed in 15 of the patients. Nine of the patients developed keratitis; four, conjunctivitis; and three, blebitis. M lacunata (6 eyes), M catarrhalis (6), M nonliquefaciens (3), and M osloensis (1) were identifed by MALDI-TOF MS. All isolates were sensitive to levofoxacin, tobramycin, ceftazidime, ceftriaxone, and cefa- zolin. Twelve patients with keratitis or blebitis were treated with various topical antimicrobial combinations, and systemic antibiotics were used in 10 of the 12 patients.
    [Show full text]
  • Clinical Antibiotic Guidelines†
    CLINICAL ANTIBIOTIC GUIDELINES† ACYCLOVIR IV*/PO *RESTRICTED TO ANTIBIOTIC FORM Predictable activity: Unpredictable activity: No activity: Herpes Simplex Cytomegalovirus Epstein Barr Virus Herpes Zoster Indicated: IV: 1. Therapy for suspected or documented Herpes simplex encephalitis 2. Therapy for suspected or documented Herpes simplex infection of a newborn or immunocompromised patient 3. Therapy for primary varicella infection in immunocompromised patients 4. Therapy for severe or disseminated varicella-zoster infections in immunocompromised or immunocompetent patient 5. Therapy for primary genital herpes with neurologic complications Oral: 1. Therapy for primary Herpes simplex infections (oral/genital) 2. Suppressive (preventative) therapy for recurrent (³ 6 episodes/year) severe Herpes simplex infections (oral/genital) 3. Episodic therapy for recurrent (³ 6 episodes/year) Herpes simplex genital infections (initiate within 24 hours of prodrome onset) 4. Prophylaxis for HSV in bone marrow transplants where patient is seropositive 5. Therapy and suppressive therapy for Eczema Herpeticum 6. Therapy for varicella-zoster infections in immunocompetent and immunocompromised patients (if not severe) 7. Therapy for primary varicella infections in pregnancy 8. Therapy for varicella in immunocompetent patients > 13 years old (initiate within 24 hours of rash onset) 9. Therapy for varicella in patients < 13 years old (initiate within 24 hours of rash onset) if there is a chronic cutaneous or pulmonary disorder, long term salicylate therapy, or short, intermittent or aerosolized corticosteroid use Not Indicated: 1. Therapy for acute Epstein-Barr infections (acute mononucleosis) 2. Therapy for documented CMV infections CLINICAL ANTIBIOTIC GUIDELINES† AMIKACIN RESTRICTED TO ANTIBIOTIC FORM Predictable activity: Unpredictable activity: No activity: Enterobacteriaceae Staphylococcus spp Streptococcus spp Pseudomonas spp Enterococcus spp some Mycobacterium spp Alcaligenes spp Anaerobes Indicated: 1.
    [Show full text]
  • BIAXIN® XL Filmtab® (Clarithromycin Extended-Release Tablets) BIAXIN® Granules (Clarithromycin for Oral Suspension, USP)
    dn2871v1-biaxin-redline-2013-oct-25 BIAXIN® Filmtab® (clarithromycin tablets, USP) BIAXIN® XL Filmtab® (clarithromycin extended-release tablets) BIAXIN® Granules (clarithromycin for oral suspension, USP) To reduce the development of drug-resistant bacteria and maintain the effectiveness of BIAXIN and other antibacterial drugs, BIAXIN should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. DESCRIPTION Clarithromycin is a semi-synthetic macrolide antibiotic. Chemically, it is 6-0­ methylerythromycin. The molecular formula is C38 H69 NO13 , and the molecular weight is 747.96. The structural formula is: Clarithromycin is a white to off-white crystalline powder. It is soluble in acetone, slightly soluble in methanol, ethanol, and acetonitrile, and practically insoluble in water. BIAXIN is available as immediate-release tablets, extended-release tablets, and granules for oral suspension. Reference ID: 3599379 dn2871v1-biaxin-redline-2013-oct-25 Each yellow oval film-coated immediate-release BIAXIN tablet (clarithromycin tablets, USP) contains 250 mg or 500 mg of clarithromycin and the following inactive ingredients: 250 mg tablets: hypromellose, hydroxypropyl cellulose, croscarmellose sodium, D&C Yellow No. 10, FD&C Blue No. 1, magnesium stearate, microcrystalline cellulose, povidone, pregelatinized starch, propylene glycol, silicon dioxide, sorbic acid, sorbitan monooleate, stearic acid, talc, titanium dioxide, and vanillin. 500 mg tablets: hypromellose, hydroxypropyl cellulose, colloidal silicon dioxide, croscarmellose sodium, D&C Yellow No. 10, magnesium stearate, microcrystalline cellulose, povidone, propylene glycol, sorbic acid, sorbitan monooleate, titanium dioxide, and vanillin. Each yellow oval film-coated BIAXIN XL tablet (clarithromycin extended-release tablets) contains 500 mg of clarithromycin and the following inactive ingredients: cellulosic polymers, D&C Yellow No.
    [Show full text]
  • Use of the Diagnostic Bacteriology Laboratory: a Practical Review for the Clinician
    148 Postgrad Med J 2001;77:148–156 REVIEWS Postgrad Med J: first published as 10.1136/pmj.77.905.148 on 1 March 2001. Downloaded from Use of the diagnostic bacteriology laboratory: a practical review for the clinician W J Steinbach, A K Shetty Lucile Salter Packard Children’s Hospital at EVective utilisation and understanding of the Stanford, Stanford Box 1: Gram stain technique University School of clinical bacteriology laboratory can greatly aid Medicine, 725 Welch in the diagnosis of infectious diseases. Al- (1) Air dry specimen and fix with Road, Palo Alto, though described more than a century ago, the methanol or heat. California, USA 94304, Gram stain remains the most frequently used (2) Add crystal violet stain. USA rapid diagnostic test, and in conjunction with W J Steinbach various biochemical tests is the cornerstone of (3) Rinse with water to wash unbound A K Shetty the clinical laboratory. First described by Dan- dye, add mordant (for example, iodine: 12 potassium iodide). Correspondence to: ish pathologist Christian Gram in 1884 and Dr Steinbach later slightly modified, the Gram stain easily (4) After waiting 30–60 seconds, rinse with [email protected] divides bacteria into two groups, Gram positive water. Submitted 27 March 2000 and Gram negative, on the basis of their cell (5) Add decolorising solvent (ethanol or Accepted 5 June 2000 wall and cell membrane permeability to acetone) to remove unbound dye. Growth on artificial medium Obligate intracellular (6) Counterstain with safranin. Chlamydia Legionella Gram positive bacteria stain blue Coxiella Ehrlichia Rickettsia (retained crystal violet).
    [Show full text]
  • Moraxella Bacteremia in Cancer Patients
    Open Access Case Report DOI: 10.7759/cureus.15316 Moraxella Bacteremia in Cancer Patients Shamra Zaman 1 , John Greene 2 1. Medicine, University of South Florida, Tampa, USA 2. Internal Medicine, Moffitt Cancer Center, Tampa, USA Corresponding author: John Greene, [email protected] Abstract Moraxella is a gram-negative bacterium part of the Moraxellaceae family. It is a pathogen that is commonly found in the upper respiratory tract of humans. It is a rare cause of community-acquired pneumonia and can be found in immunocompromised individuals, especially those with impaired humoral immunity such as hypogammaglobulinemia and those with lung diseases. We present three cases of Moraxella infections at the Moffitt Cancer Center between the years 2011 and 2017. We performed a literature review of Moraxella bacteremia in cancer patients and included three patients, two with a history of multiple myeloma and one undergoing radiation therapy for non-small cell lung carcinoma. None of the patients died as a result of the infection. Moraxella infections can result in a range of severity with increasing resistance to antibiotic therapy. Categories: Infectious Disease, Oncology Keywords: moraxella, myeloma, respiratory tract, pneumonia, immunocompromised patient Introduction Moraxella is a gram-negative bacterium that has a coccobacillus shape [1]. Originally considered normal flora in the human respiratory system, it can cause respiratory tract infections [2]. It primarily affects adults with prior chronic lung disease and the immunosuppressed. The most common immunodeficiency is hypogammaglobulinemia, which is found in patients with multiple myeloma and chronic lymphocytic leukemia (CLL). Invasive infections include meningitis, pneumonia, and endocarditis [3,4]. We present the cases of three cancer patients with Moraxella infections that illustrate the most common risk factors that predispose to this infection.
    [Show full text]
  • Moraxella Catarrhalis and Haemophilus Influenzae
    The Other Siblings: Respiratory Infections Caused by Moraxella catarrhalis and Haemophilus influenzae Larry Lutwick, MD, and Laila Fernandes, MD Corresponding author Moraxella catarrhalis Larry Lutwick, MD Infectious Diseases (IIIE), VA Medical Center, 800 Poly Place, Bacteriology Brooklyn, NY 11219, USA. M. catarrhalis is a Gram negative, aerobic diplococcus E-mail: [email protected] that was initially described by Anton Ghon and Rich- Current Infectious Disease Reports 2006, 8:215–221 ard Pfeiffer as Micrococcus catarrhalis at the end of the Current Science Inc. ISSN 1523-3847 19th century. For most of the first century of its rec- Copyright © 2006 by Current Science Inc. ognition, M. catarrhalis is considered to be a human mucosal commensal organism based on its common finding as an inhabitant of the oropharynx of healthy Respiratory infections remain substantial causes of mor- adults. During a significant amount of this time, based bidity and mortality globally. In this paper, two substantial on phenotypic characteristics as well as microbiologic players in bacterial-associated respiratory disease are colony appearances, the diplococcus was referred to assessed as to their respective roles in children and adults as Neisseria catarrhalis. Of note, in 1963, N. catarrhalis and in the developed and developing world. Moraxella was found to contain two distinct species, catarrhalis catarrhalis, although initially thought to be a nonpathogen, and cinerea [1]. continues to emerge as a cause of upper respiratory Reclassification of the genus of this microorganism disease in children and pneumonia in adults. No vaccine occurred in 1970 when significant phylogenetic dispari- is currently available to prevent M.
    [Show full text]
  • Infectious Organisms of Ophthalmic Importance
    INFECTIOUS ORGANISMS OF OPHTHALMIC IMPORTANCE Diane VH Hendrix, DVM, DACVO University of Tennessee, College of Veterinary Medicine, Knoxville, TN 37996 OCULAR BACTERIOLOGY Bacteria are prokaryotic organisms consisting of a cell membrane, cytoplasm, RNA, DNA, often a cell wall, and sometimes specialized surface structures such as capsules or pili. Bacteria lack a nuclear membrane and mitotic apparatus. The DNA of most bacteria is organized into a single circular chromosome. Additionally, the bacterial cytoplasm may contain smaller molecules of DNA– plasmids –that carry information for drug resistance or code for toxins that can affect host cellular functions. Some physical characteristics of bacteria are variable. Mycoplasma lack a rigid cell wall, and some agents such as Borrelia and Leptospira have flexible, thin walls. Pili are short, hair-like extensions at the cell membrane of some bacteria that mediate adhesion to specific surfaces. While fimbriae or pili aid in initial colonization of the host, they may also increase susceptibility of bacteria to phagocytosis. Bacteria reproduce by asexual binary fission. The bacterial growth cycle in a rate-limiting, closed environment or culture typically consists of four phases: lag phase, logarithmic growth phase, stationary growth phase, and decline phase. Iron is essential; its availability affects bacterial growth and can influence the nature of a bacterial infection. The fact that the eye is iron-deficient may aid in its resistance to bacteria. Bacteria that are considered to be nonpathogenic or weakly pathogenic can cause infection in compromised hosts or present as co-infections. Some examples of opportunistic bacteria include Staphylococcus epidermidis, Bacillus spp., Corynebacterium spp., Escherichia coli, Klebsiella spp., Enterobacter spp., Serratia spp., and Pseudomonas spp.
    [Show full text]
  • Characterization of the Molecular Interplay Between Moraxella Catarrhalis and Human Respiratory Tract Epithelial Cells
    Characterization of the Molecular Interplay between Moraxella catarrhalis and Human Respiratory Tract Epithelial Cells Stefan P. W. de Vries, Marc J. Eleveld, Peter W. M. Hermans¤, Hester J. Bootsma* Laboratory of Pediatric Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands Abstract Moraxella catarrhalis is a mucosal pathogen that causes childhood otitis media and exacerbations of chronic obstructive pulmonary disease in adults. During the course of infection, M. catarrhalis needs to adhere to epithelial cells of different host niches such as the nasopharynx and lungs, and consequently, efficient adhesion to epithelial cells is considered an important virulence trait of M. catarrhalis. By using Tn-seq, a genome-wide negative selection screenings technology, we identified 15 genes potentially required for adherence of M. catarrhalis BBH18 to pharyngeal epithelial Detroit 562 and lung epithelial A549 cells. Validation with directed deletion mutants confirmed the importance of aroA (3-phosphoshikimate 1-carboxyvinyl-transferase), ecnAB (entericidin EcnAB), lgt1 (glucosyltransferase), and MCR_1483 (outer membrane lipoprotein) for cellular adherence, with ΔMCR_1483 being most severely attenuated in adherence to both cell lines. Expression profiling of M. catarrhalis BBH18 during adherence to Detroit 562 cells showed increased expression of 34 genes in cell-attached versus planktonic bacteria, among which ABC transporters for molybdate and sulfate, while reduced expression of 16 genes was observed. Notably, neither the newly identified genes affecting adhesion nor known adhesion genes were differentially expressed during adhesion, but appeared to be constitutively expressed at a high level. Profiling of the transcriptional response of Detroit 562 cells upon adherence of M. catarrhalis BBH18 showed induction of a panel of pro- inflammatory genes as well as genes involved in the prevention of damage of the epithelial barrier.
    [Show full text]