Microbiology in Your Pocket E-Book

Melphine Harriott

• Herausgeber: Thieme Medical Publishers
• Kategorie: Fachliteratur
• Sprache: Englisch

Veröffentlichungsjahr: 2017

Beschreibung

Highly Commended by the BMA Medical Book Awards for Basic & Clinical Sciences!

Microbiology in Your Pocket: Quick Pathogen Review by Melphine Harriott is a concise guide to common and rare bacteria, viruses, fungi, and parasites that begins with pathogens that infect the nervous system and ends with pathogens infecting multiple organs. The presentation of material by organ system facilitates easy organization and provides versatility of use.

Each card presents similar information with variations due to inherent pathogen differences. On the front is an introduction to each pathogen with clinical vignettes and images. The back provides the taxonomy or morphology, infections, pathogenesis, epidemiology, diagnosis, prevention, treatment options, and an explanation.

Key Features

• More than 230 graphics including full-color clinical images, pathogen photomicrographs, cell stains, biochemical tests, and diagrams
• Six color-coded pathogen types further facilitate quick acquisition of knowledge
• Promotes long-term retention of complex material
• Animations further enhance learning

This is an essential guide for medical students preparing for the USMLE®. It is also an ideal choice for graduate-level students in health science and dentistry looking for a user-friendly microbiology review.

Leseprobe

To access additional material or resources available with this e-book, please visit http://www.thieme.com/bonuscontent. After completing a short form to verify your e-book purchase, you will be provided with the instructions and access codes necessary to retrieve any bonus content.

Microbiology in Your Pocket

Quick Pathogen Review

Melphine Harriott, PhD

Fellow, Clinical MicrobiologyDepartment of Pathology, Microbiology and ImmunologyVanderbilt University Medical CenterNashville, Tennessee, USA

313 illustrations

ThiemeNew York • Stuttgart • Delhi • Rio de Janeiro

Acquisitions Editor: Delia K. DeTurrisDevelopmental Editor: Julia NollenManaging Editor: Torsten ScheihagenEditorial Director, Educational Products: Anne M. Sydor, PhDDirector, Editorial Services: Mary Jo CaseyProduction Editor: Barbara ChernowInternational Production Director: Andreas SchabertInternational Marketing Director: Fiona HendersonInternational Sales Director: Louisa TurrellDirector of Sales, North America: Mike RosemanSenior Vice President and Chief Operating Officer: Sarah VanderbiltPresident: Brian D. ScanlanTypesetter: Carol Pierson, Chernow Editorial Associates, Inc.

Library of Congress Cataloging-in-Publication DataNames: Harriott, Melphine, author.Title: Microbiology in your pocket: quick pathogen review/Melphine Harriott.Description: New York: Thieme, [2018]Identifiers: LCCN 2017013563 (print) | LCCN 2017014708 (ebook) | ISBN 9781626234154 (alk. paper) |   ISBN 9781626234161 (eISBN)Subjects: | MESH: Bacterial Infections | Virus Diseases | Protozoan Infections | Virulence | Case Reports |   Problems and ExercisesClassification: LCC RA644.B32 (ebook) | LCC RA644.B32 (print) | NLM WC 18.2 | DDC 614.5/7—dc23LC record available at https://lccn.loc.gov/2017013563

Copyright © 2018 by Thieme Medical Publishers, Inc.

Thieme Publishers New York333 Seventh Avenue, New York, NY 10001 USA+1 800 782 3488, [email protected]

Thieme Publishers StuttgartRüdigerstrasse 14, 70469 Stuttgart, Germany+49 [0]711 8931 421, [email protected]

Thieme Publishers DelhiA-12, Second Floor, Sector-2, Noida-201301Uttar Pradesh, India [phone], [email protected]

Thieme Publishers Rio de Janeiro, Thieme Publicações Ltda.Edifício Rodolpho de Paoli, 25° andarAv. Nilo Peçanha, 50 – Sala 2508Rio de Janeiro 20020-906 Brasil+55 21 3172-2297/[phone]

Cover design: Thieme Publishing Group

Printed in China by Everbest Printing Co.

5 4 3 2 1

ISBN 978-1-62623-415-4

Also available as an e-book:eISBN 978-1-62623-416-1

Important note: Medicine is an ever-changing science undergoing continual development. Research and clinical experience are continually expanding our knowledge, in particular our knowledge of proper treatment and drug therapy. Insofar as this book mentions any dosage or application, readers may rest assured that the authors, editors, and publishers have made every effort to ensure that such references are in accordance with the state of knowledge at the time of production of the book.

Nevertheless, this does not involve, imply, or express any guarantee or responsibility on the part of the publishers in respect to any dosage instructions and forms of applications stated in the book. Every user is requested to examine carefully the manufacturers’ leaflets accompanying each drug and to check, if necessary in consultation with a physician or specialist, whether the dosage schedules mentioned therein or the contraindications stated by the manufacturers differ from the statements made in the present book. Such examination is particularly important with drugs that are either rarely used or have been newly released on the market. Every dosage schedule or every form of application used is entirely at the user's own risk and responsibility. The authors and publishers request every user to report to the publishers any discrepancies or inaccuracies noticed. If errors in this work are found after publication, errata will be posted at www.thieme.com on the product description page.

Some of the product names, patents, and registered designs referred to in this book are in fact registered trademarks or proprietary names even though specific reference to this fact is not always made in the text. Therefore, the appearance of a name without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain.

This book, including all parts thereof, is legally protected by copyright. Any use, exploitation, or commercialization outside the narrow limits set by copyright legislation, without the publisher's consent, is illegal and liable to prosecution. This applies in particular to photostat reproduction, copying, mimeographing, preparation of microfilms, and electronic data processing and storage.

This work is dedicated to all my past and future students who motivate me to be better and to learn more.

I am indebted to my husband, Alwyn, and my parents Melchizedek and Josephinefor their encouragement and support during the development of this project.

Contents

Preface

Acknowledgments

Abbreviations

Chapter 1 Nervous System

1. Clostridium botulinum

2. Clostridium tetani

3. Listeria monocytogenes

4. Neisseria meningitidis

5. Streptococcus agalactiae

6. Bunyavirus

7. Arthropod borne flaviruses

8. Poliovirus

9. Rabies virus

10. Alphavirus

11. Cryptococcus neoformans amd gatti

12. Naegleria fowleri

13. Taenia solium

14. Toxoplasma gondii

Chapter 2 Head and Neck

15. Actinomyces israelii

16. Moraxella catarrhalis

17. Corynebacterium diphtheriae

18. Adenovirus

19. Mumps virus

20. Mucor and Rhizopus

21. Acanthamoeba

22. Onchocerca volvulus

Chapter 3 Respiratory System

23. Bordetella pertussis

24. Chlamydophila (Chlamydia) pneumoniae and psittaci

25. Legionella pneumophila

26. Mycobacterium tuberculosis (MTB)

27. Mycoplasma pneumoniae

28. Nocardia

29. Coronavirus

30. Influenza virus

31. Parainfluenza virus

32. Respiratory syncytial virus (RSV)

33. Rhinovirus

34. Aspergillus fumigatus

35. Blastomyces dermatitidis

36. Coccidioides immitis and posadasii

37. Histoplasma capsulatum

38. Paracoccidioides brasiliensis

39. Pneumocystis jirovecii (carinii)

40. Paragonimus westermani

Chapter 4 Blood/Lymph/Systemic/Cardiovascular Systems

41. Ehrlichia and Anaplasma

42. Bartonella

43. Borrelia recurrentis and hermsii

44. Brucella

45. Leptospira interrogans

46. Rickettsia

47. Salmonella enterica serotype typhi and paratyphi

48. Cytomegalovirus (CMV)

49. Colorado tick virus

50. Ebola and Marburg viruses

51. Epstein-Barr virus (EBV)

52. Human herpes virus-6 (HHV-6)

53. Human immunodeficiency virus (HIV)

54. Lassa virus

55. Parvovirus B19

56. Babesia microti

57. Brugia malayi and Wuchereria bancrofti

58. Loa loa

59. Plasmodium

60. Trypanosoma

Chapter 5 Gastrointestinal System

61. Bacillus cereus

62. Campylobacter jejuni

63. Clostridium difficile

64. Enteroaggregative Escherichia coli (EAEC)

65. Enterohemorrhagic Escherichia coli (EHEC)

66. Enteroinvasive Escherichia coli (EIEC)

67. Enteropathogenic Escherichia coli (EPEC)

68. Enterotoxigenic Escherichia coli (ETEC)

69. Helicobacter pylori

70. Nontyphoidal Salmonella

71. Shigella

72. Noncholera Vibrio

73. Vibrio cholerae

74. Yersinia enterocolitica and pseudotuberculosis

75. Norwalk virus

76. Rotavirus

77. Encephalitozoon (Microsporidia) and Enterocytozoon

78. Ancylostoma duodenale and Necator americanus

79. Ascaris lumbricoides

80. Cryptosporidium

81. Cyclospora cayetanensis

82. Diphyllobothrium latum

83. Entamoeba histolytica

84. Enterobius vermicularis

85. Giardia lamblia

86. Strongyloides stercoralis

87. Taenia saginata

88. Trichuris trichiura

Chapter 6 Liver/Biliary System

89. Hepatitis A virus (HAV)

90. Hepatitis B virus (HBV)

91. Hepatitis C virus (HCV)

92. Hepatitis D virus (HDV)

93. Hepatitis E virus (HEV)

94. Clonorchis sinensis

95. Echinococcus granulosus

96. Fasciola hepatica

Chapter 7 Renal/Urinary Systems

97. Proteus mirabilis

98. Staphylococcus saprophyticus

99. Schistosoma haematobium

Chapter 8 Reproductive System

100. Chlamydia trachomatis

101. Gardnerella vaginalis

102. Haemophilus ducreyi

103. Klebsiella granulomatis

104. Mycoplasma and Ureaplasma

105. Neisseria gonorrhoeae

106. Treponema pallidum

107. Human papillomavirus (HPV)

108. Trichomonas vaginalis

Chapter 9 Skin/Soft Tissue/Musculoskeletal

109. Bacillus anthracis

110. Clostridium perfringens

111. Francisella tularensis

112. Mycobacterium leprae

113. Pasteurella multocida

114. Measles virus

115. Molluscum contagiosum virus

116. Smallpox virus (Variola virus)

117. Varicella-zoster virus

118. Dermatophytes: Epidermophyton, Microsporum, Trichophyton

119. Malassezia furfur

120. Sporothrix schenckii

121. Leishmania

122. Schistosoma mansoni and japonicum

123. Trichinella spiralis

Chapter 10 Multiple Organ Systems

124. Bacteroides

125. Borrelia burdgorferi

126. Coagulase-negative Staphylococcus

127. Coxiella burnetii

128. Enterococcus

129. Escherichia coli

130. Haemophilus influenzae

131. Klebsiella pneumoniae

132. Nontuberculosis Mycobacterium

133. Pseudomonas aeruginosa

134. Staphylococcus aureus

135. Streptococcus pyogenes

136. Streptococcus pneumoniae

137. Viridans streptococci

138. Yersinia pestis

139. Herpes simplex virus (HSV)-1 and -2

140. Non-Polio Enterovirus

141. BK and JC viruses

142. Rubella virus

143. Candida species

144. Toxocara

Appendix

A1. Gram Stain Reactions for Select Clinically Significant Organisms

A2. Common Clinical Microbiology Media

A3. Clinically Significant Anaerobes

A4. Comparison of Escherichia coli Strains

A5. Summary of Clinically Significant Viruses

A6. Viral Hepatitis Summary Table

A7. Parasite Flow Chart: Protozoa

A8. Parasite Flow Chart: Worms

A9. Characteristic AIDS-Defining Infectious Diseases

A10. Comparison of Genital Ulcer Disease

A11. Vaginitis/Vaginosis Differentiation

A12. Vector Borne Infections

Preface

Microbiology in Your Pocket: Quick Pathogen Review is a collection of notecards intended to aid medical students, physician assistant students, dental students, and other graduate health science students while studying for a medical microbiology course. These cards can also be utilized as a supplemental study tool for the preparation of United States Medical Licensing Examination (USMLE) Step 1, Comprehensive Osteopathic Medical Licensing Examination (COMLEX) Level 1, Physician Assistant National Certifying Exam (PANCE) and National Board Dental Examination (NBDE).

The cards contain high-yield information that encompasses many of the clinically significant bacteria, viruses, yeast, and parasites that are covered in a graduate level medical microbiology course or on a board exam. It was not feasible to cover all clinically relevant microorganisms or all pertinent information regarding each microbe in this succinct review, hence students should use this as a supplement rather than the sole source in preparation for a course or board examination.

The cards are color coded by pathogen type using the following color scheme:

Pink: Gram-negative bacteriaPurple: Gram-positive bacteriaGray: Organisms that do not Gram stain or Gram stain poorlyGreen: VirusesBlue: FungiOrange: Parasites

Each pathogen/card is assigned a primary organ system when possible and cards are organized by this primary organ system assignment. Primary organ systems include:

Nervous SystemHead and NeckRespiratory SystemBlood/Lymph/Systemic InfectionsGastrointestinal SystemLiver and Biliary SystemRenal and Urinary SystemsReproductive SystemSkin, Soft Tissue, and Musculoskeletal Systems

However, note that it is not possible to assign a primary organ system to some pathogens since they may infect multiple anatomic sites. Hence, these pathogens are in a chapter designated Multiple Organ Systems.

Each card contains similar information. The various sections of each card are explained in further detail below:

Micro gem: The front of some cards contains a “Micro gem” which is small bit of free-standing information that is pertinent to the microorganism presented on the card.

Vignette(s): The front of each card contains one or more clinical vignettes. An explanation for each vignette is on the back of the same card.

Images: Most cards contain images such as microscopic images of the pathogen, biochemical tests or clinical images of infections with the pathogen. Note that although the images are on the front of the card are numbered and appear under the vignette, the images are are linked to concepts found on the back of the card.

The back of each card contains the following:

Description: For bacteria, this section includes Gram stain reaction/morphology and other descriptive features of the organism. For viruses, this includes the viral taxonomy and a description of the genetic nature of the virus. For fungi, this section includes a microscopic description of the characteristic features of the fungi. Lastly, for parasites, the taxonomy, alternative name as well the microscopic features of the parasite are listed in this section.

Infections: As previously mentioned, when possible organisms were assigned a primary organ system based on the chief infectious disease associated with that pathogen. Other infections that may be less common are listed under the heading “Other”. Note that this section does not contain a comprehensive list of all the potential infections associated with a pathogen, but rather the most common conditions.

Pathogenesis: Most cards will have a pathogenesis/virulence mechanism, such as toxin production, listed in this section.

Epidemiology: Each card contains epidemiological information including transmission and groups that are at high risk for infections with that pathogen.

Diagnosis: Each card has select microbiologic diagnostic tests that may be used to identify the organism. Note this is not a comprehensive list and actual diagnostic testing may vary based on the clinical situation.

Prevention: Some cards have examples of prevention methods, such as immunization, listed in this section.

Treatment: Each card contains examples of effective antimicrobials for the pathogen. This information should not be utilized for actual clinical treatment as many factors must be considered when making decisions regarding antimicrobial therapy.

Animation(s): Some cards contain animations that provide a more detailed explanation of the pathogenesis mechanism. These animations may be accessed via WinkingSkull.com; please see the scratch-off page on the inside front cover for instructions on how to access the site.

Explanation: Each card contains explanations for the vignettes which are on the front of the card.

Cross-references: To assist students in making correlations between organisms and/or infections, some cards contain cross-references to other cards. These cross-references include the number of the card, which will enable readers to locate them.

There are also cross-references to indicate a similarity between organisms. For example within the Diagnosis section of the Listeria monocytogenes card, note the cross-reference to Streptococcus agalactiae which is indicated in the following manner: CAMP test positive with block head hemolysis (2). See also•5, Streptococcus agalactiae•. Both organisms are CAMP test positive and students may refer to the S. agalactiae (which is Gram positive as indicated by the purple dots) card for further details.

Appendix: The appendix contains tables, line art, and graphs that summarize information presented throughout the cards.

Melphine Harriott, PhD

Acknowledgments

I am extremely grateful for the following students who assisted me in the development of Microbiology in Your Pocket: Quick Pathogen Review:

Joshua McCarron—Joshua assisted in the development of the initial version of the notecards while a second-year medical student at Oakland University William Beaumont School of Medicine. He is now completing an internal medicine residency at Wright State University/Wright-Patterson Air Force Base.

Erik Sweet — Erik developed the initial web-based version of the notecards during his first year at Oakland University William Beaumont School of Medicine. He is now an ophthalmology resident at the University of Michigan.

Paige Peterson and Lauren McNickle—assisted in modifying and editing the original notecards. Without their hard work, this project would have not been completed in a timely manner. Both Paige and Lauren worked on this project during their fourth year at Frank H. Netter MD School of Medicine/Quinnipiac University. Paige and Lauren were fourth and third year medical students respectively at the Frank H Netter MD School of Medicine/Quinnipiac University while working on this project. Paige will soon be starting the Anatomic and Clinical Pathology Residency Program at the University of Colorado.

This work was completed in part while the author had the following affiliations:

Assistant ProfessorMidwestern UniversityChicago College of Osteopathic MedicineDowners Grove, Illinois, USA

Assistant ProfessorOakland UniversityWilliam Beaumont School of MedicineRochester, Michigan, USA

Abbreviations

ACh

acetylcholine

ADP

adenosine diphosphate ribose

AFB

acid-fast bacilli

AIDS

acquired immunodeficiency syndrome

ALT

alanine amino transferase

AST

aspartate amino transferase

ATP

adenosine triphosphate

cGMP

cyclic GMP

CAMP

Christie-Atkins-Munch-Peterson

cAMP

cyclic adenosine monophosphate

CBC

complete blood count

CDC

Centers for Disease Control

CFU

colony forming unit

cGMP

cyclic guanosine monophosphate

CO2

carbon dioxide

COPD

chronic obstructive pulmonary disease

CSF

cerebrospinal fluid

CT

computed tomography

DIC

disseminated intravascular coagulation

DFA

direct fluorescent antibody

EAEC

enteroaggregative Escherichia coli

EAST

enteroaggregative heat stable toxin

EHEC

enterohemorrhagic Escherichia coli

EPEC

enteropathogenic Escherichia coli

EIA

enzyme immunoassay

EIEC

enteroinvasive Escherichia coli

ELISA

enzyme linked immunosorbent assay

ETEC

enterotoxigenic Escherichia coli

HIV

human immunodeficiency virus

IL

interleukin

INF

interferon

GABA

gamma aminobutyric acid

GI

gastrointestinal

GNC

gram-negative cocci

GNR

gram-negative rod

GPC

gram-positive cocci

GPR

gram-positive rod

HIV

human immunodeficiency virus

IV

intravenous

IVDU

intravenous drug use

KOH

potassium hydroxide

LPS

lipopolysaccharide

MAP

mitogen-activated protein

MCV

mean corpuscular volume

MHC

major histocompatibility complex

MRI

magnetic resonance imaging

O&P

ova and parasite

PCR

polymerase chain reaction

PMNs

polymorphonuclear cell

RBC

red blood cell

SNARE

soluble attachment protein receptor

STEC

shiga-toxin producing E. coli

TNF

tumor necrosis factor

U.S.

United States

UTIs

urinary tract infections

WBC

white blood cell

Chapter 1 Nervous System

1 Clostridium botulinum

Micro gem:

Both Clostridium and Bacillus are gram-positive rods with spores . Clostridium are anaerobic, whereas Bacillus are aerobic. See also•63, Clostridium difficile•; •110, Clostridium perfringens•; •2, Clostridium tetani•; •109, Bacillus anthracis•; •61, Bacillus cereus•

Vignette 1: A 42-year-old woman presents to the emergency department with nausea, vomiting, abdominal pain, and diarrhea of 24 hours’ duration. Her husband sought medical assistance for her when he noticed she was experiencing dry mouth, difficulty with her vision, and weakness in her arms. The husband states that his wife recently consumed home-canned peaches.

Vignette 2: A 4-month-old infant presents to the emergency department with decreased movement. The parents state that the child has been irritable, drooling, and not feeding well for the past 3 days. The child is breast-fed, and the mother states that she noticed a decreased ability to suck and that the baby's cry seems “weak” and “not normal.” On examination, the child has noticeable hypotonia, with poor head control and is dehydrated. The child's temperature at the time of examination is 37.2°C (99°C). The cerebrospinal fluid analysis is unremarkable.

(1)

(2) Source: National Institutes of Health (https://www.nlm.nih.gov/medlineplus/ency/imagepages/17229.htm)

DESCRIPTION

Gram-positive rods, large, boxcar shaped (1)

Spore-producer (1)

Obligate anaerobe

INFECTIONS

Botulism

PRIMARY

Nervous

Foodborne adult botulism: 12- to 36-hour incubation; fixed or dilated pupils, diplopia, difficulty swallowing, dry mouth, and descending paralysis (limp/flaccid muscles) Infant botulism/floppy baby syndrome (2): hypotonia

OTHER

Skin and soft tissue: wound botulism

PATHOGENESIS

Exotoxin/neurotoxin: botulinum toxin types A–G: heat-labile protease that cleaves SNAREs and prevents ACh release at neuromuscular junction

EPIDEMIOLOGY

Spores found in soil

Transmission: Foodborne adult botulism: ingestion of preformed toxin in food—commonly associated foods include smoked, vacuum-packed and alkaline home-canned foods

Infant botulism: most likely inhalation of spores that colonize GI tract and produce toxin in vivo (in the past mainly attributed to ingestion and was commonly associated with honey and powdered formula)

Wound botulism: bacteria infects wound, then forms toxin in vivo

DIAGNOSIS

Toxin detection

Foodborne adult botulism: serum (preferred), stool or vomitus

Infant botulism: stool

Wound: pus or tissue from wound site

TREATMENT

Antimicrobials not proven effective

However, penicillin G, metronidazole may be used

Aminoglycosides are not typically used because they enhance the neuromuscular blockade caused by the toxin

Antitoxin

Equine derived—for adults only

Human-derived immunoglobulin (baby immunoglobulin [BabyBIG] or BIG-IV)—for infants < 1-year-old

ANIMATION

http://go.thieme.com/microb/Video1.1

Explanation 1:Clostridium botulinum is an anaerobic gram-positive rod with spores. This pathogen may cause wound infections, infant botulism, or foodborne infections, such as in this case. Adult foodborne botulism is associated with canned foods, including vegetables, fruit, and fish. The classic presentation is dry mouth and descending weakness. This is due to the botulinum toxin that inhibits release of acetylcholine.

Explanation 2:Clostridium botulinum is an anaerobic gram-positive rod with spores. This pathogen may cause wound infections, foodborne infections, or infant botulism, such as in this case. In the past, infant botulism was associated with honey, but recently it is thought that infections arise from inhalation of spores that may be found in the soil and dusty environments. The classic presentation of infant botulism is a “floppy” baby (i.e., hypotonia). Unlike adults, infants especially from birth to 12 months do not have the appropriate immune response and intestinal flora to prevent infections with this organism, especially if the inoculum concentration is high. The botulinum toxin inhibits release of acetylcholine.

2 Clostridium tetani

Micro gem:

The tetanus toxin inhibits inhibitory neurotransmitters, GABA and glycine, while the botulinum toxin inhibits the excitatory neurotransmitter, ACh. See also•1, Clostridium botulinum•

Vignette: A 58-year-old homeless man is brought to the emergency department by the police, who have found him under the influence of drugs and alcohol, missing shoes and socks, and barely responsive. Upon examination his temperature is 40.1°C (104°F), his heart rate is 90 beats/min, and his blood pressure is 60/40 mm Hg. In addition, he is having difficulty breathing, and his neck is stiff and hyperextended. Trismus and opisthotonic posturing are also noted. His feet are obviously gangrenous and ulcerated.

(1) Source: CDC/Dr. Lillian V. Holdeman CDC public health library PHIL (phil.cdc. gov) image No. 12056 (http://phil.cdc.gov/phil/details_linked.asp?pid=12056)

(2) Source: CDC public health library PHIL (phil.cdc.gov) image No. 6373 (http://phil.cdc.gov/phil/details_linked.asp?pid=6373)

(3) Source: CDC/Dr. Thomas F. Sellers/Emory University CDC public health library PHIL (phil.cdc.gov) image No. 2857 (http://phil.cdc.gov/phil/details_linked.asp?pid=2857)

(4) Source: CDC public health library PHIL (phil.cdc.gov) image No. 6374 (http://phil.cdc.gov/phil/details_linked.asp?pid=6374)

DESCRIPTION

Gram-positive rods (1), large, boxcar shaped Spore-producer

Obligate anaerobe

INFECTIONS

Tetanus

PRIMARY

Nervous: tetanus—generalized tetanus (2,3); results in muscle rigidity/spastic paralysis with trismus (lockjaw) and risus sardonicus (grinning expression resulting from facial muscle spasm)

OTHER

Head and neck: localized tetanus

Neonatal (rare): neonatal tetanus (4)

PATHOGENESIS

Exotoxin/neurotoxin: tetanospasmin—protease that cleaves SNAREs and prevents release of GABA and/or glycine at alpha motor neuron

Binds to end of motor neurons and is transported in a retrograde manner to nervous system

EPIDEMIOLOGY

Spores found in the soil

Transmission:

Direct contact with spores—most often after trauma to skin Neonatal—associated with umbilical cord contamination at delivery

DIAGNOSIS

Usually made on clinical findings

PREVENTION

Vaccine: toxoid vaccines—DTaP, DT, Td, Tdap Boosters required

TREATMENT

Antimicrobial: to target bacteria

Effective antimicrobial agents include metronidazole and penicillin

Human tetanus immune globulin (HTIG): to target unbound toxin

HTIG can only bind and remove toxin that has not yet bound to a nerve ending.

ANIMATION

http://go.thieme.com/microb/Video2.1

Explanation: This man has tetanus which is caused by Clostridium tetani. This pathogen is an anaerobic gram-positive rod with spores. It produces a toxin that prevents neurons from releasing GABA and glycine. The symptoms described in this case are classic symptoms observed with tetanus. The lack of shoes and socks provides a route of transmission for spores, which are found in soil.

3 Listeria monocytogenes

Micro gem: The most common bacterial agents of neonatal meningitis are Listeria monocytogenes,•5, Streptococcus agalactiae •, and •129, Escherichia coli K1 •

Vignette: A 45-year-old woman presents to the emergency department with ataxia and tremors. She states that a few days prior she had experienced a severe headache, fever, and stiff neck. In addition, she has recently been diagnosed with acute myeloid leukemia and is currently undergoing treatment. She mentions that she lives on a goat farm and makes and sells homemade cheese. Her temperature is 38.4°C (101.1°F). CSF analysis demonstrates low glucose, elevated protein, and elevated neutrophils. A Gram stain from the CSF shows gram-positive rods.

(1) Source: CDC/Dr. Balasubr Swaminathan; Peggy Hayes CDC public health library PHIL (phil.cdc.gov) image No. 10828 (http://phil.cdc.gov/phil/details_linked.asp?pid=10828)

(2)

(3)

DESCRIPTION

Short gram-positive rods or coccobacilli (1)

INFECTIONS

PRIMARY

Gastrointestinal: gastroenteritis—diarrhea

Nervous: meningitis, meningoencephalitis

Systemic: bacteremia; during pregnancy, infections manifest as febrile “flu-like” illness which can cause spontaneous abortions/fetal death

Neonatal: meningitis

Congenital: granulomatosis infantiseptica

PATHOGENESIS

Facultative intracellular pathogen

Exotoxin/cytotoxin: listeriolysin O (LLO)—assists with intracellular survival and escape

actA: used to create actin tail; propels itself through cell cytoplasm by assembly of this actin tail. See also•71, Shigella•

EPIDEMIOLOGY

Transmission:

Post-natal infections: foodborne—commonly associated foods include soft cheese, unpasteurized milk, cold deli meats, ice cream, fruits, vegetables Congenital and neonatal: vertical (in utero or perinatal)

Mild infections in immunocompetent

High risk for meningitis:

Neonates

Elderly

Individuals with decreased cell-mediated immunity

DIAGNOSIS

Culture: beta-hemolytic, catalase positive, growth in cold (4°C), CAMP test positive with block-head hemolysis (2). See also•5, Streptococcus agalactiae•

Motility: tumbling on wet preparation or umbrella-shaped in semi-solid media (3) at room temperature (25°C)

TREATMENT

Depends on age, immune status: meningitis/meningoencephalitis Ampicillin plus gentamicin

ANIMATION

http://go.thieme.com/microb/Video3.1

Explanation:Listeria monocytogenes is a facultative intracellular gram-positive rod. Infections are transmitted from contaminated food and unlike most pathogenic organisms, Listeria can endure cold temperatures, which allows it to survive refrigeration. In immunocompetent individuals, infections are asymptomatic or manifest as mild gastroenteritis. However in neonates, the elderly and immunocompromised individuals meningitis may occur. This organism has several mechanisms of pathogenesis including production of exotoxins, invasion of host cells, intracellular survival, and propulsion from cell-to-cell within the host.

4 Neisseria meningitidis

Micro gem: Splenic macrophages facilitate opsonization and phagocytosis of encapsulated bacteria. Therefore, asplenic individuals are at increased risk for infections with pathogens containing polysaccharide capsules including Neisseria meningitidis,•136, Streptococcus pneumoniae•, and •130, Haemophilus influenzae•.

Vignette: A 19-year-old male college student presents to the emergency department with a fever and lethargy. His roommate states he appeared normal the evening before but had complained of a severe headache. That morning the roommate found him in bed moaning and complaining of drowsiness and neck pain. At the time of examination his temperature is 40.3°C (104.5°F). In addition, nuchal rigidity and a purpuric rash on his legs and trunk are noted. A lumbar puncture demonstrates decreased CSF glucose, elevated CSF protein, and elevated CSF white blood cells, particularly neutrophils. The CSF Gram stain demonstrates the presence of gram-negative diplococci.

(1)

(2) Source: Petechial rash, User: DrFO.Jr.Tn (own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Petechial_rash.JPG)

DESCRIPTION

Gram-negative diplococci, kidney/coffee bean-shaped (1) Clinically significant serogroups include A, B, C, X, Y, Z, W135, and L

Alternative name: meningococcus (MC)

INFECTIONS

PRIMARY

Nervous: meningitis with or without meningococcemia Systemic: meningococcemia; DIC and petechial rash may occur (2); severe infection associated with Waterhouse-Friderichsen syndrome

PATHOGENESIS

Capsule

Endotoxin/lipooligosaccharide (LOS): similar function as LPS Pili: capable of phase and antigenic variation Outer membrane proteins: opacity (opa) proteins—assist in adhesion—capable of phase and antigenic variation IgA protease: destroys IgA

See also•105, Neisseria gonorrhoeae•; •130, Haemophilus influenzae•; •136, Streptococcus pneumoniae•

EPIDEMIOLOGY

Transmission: respiratory droplets

High risk:

Children and young adults

Individuals living in close quarters, such as college and military campuses

Individuals with complement deficiency (C5–C9)

Asplenic individuals

PREVENTION

Vaccine: currently available for A, B, C, W, and Y serogroups

Conjugate vaccine: infants, children, and adults Polysaccharide vaccine: older adults/elderly Recombinant vaccine (for serogroup B only): young adults

DIAGNOSIS

Culture: fastidious, best growth on chocolate or selective media such as Thayer-Martin. See also•105, Neisseria gonorrhoeae•PCR from CSF

Latex agglutination for capsular serogroup

TREATMENT

Ceftriaxone

ANIMATION

http://go.thieme.com/microb/Video4.1; http://go.thieme.com/microb/Video4.2

Explanation: This man has meningitis caused by Neisseria meningitidis. Populations in close quarters, such as on college campuses and military bases, are at a higher risk for meningitis with this organism. N. meningitidis is a gram-negative diplococcus and is often referred to as meningococcus. The main mechanism of virulence is a capsule. Meningitis may be present in conjunction with meningococcemia. Alternatively, meningitis or meningococcemia may be present independent of one another. The petechial rash is a classic sign of infection of the organism, but note that the rash is not always present. CSF findings of decreased glucose, elevated protein, and elevated neutrophils are consistent with bacterial infection.

5 Streptococcus agalactiae

Vignette: A 1-day-old infant develops a fever, poor feeding, and irritability. The baby was born full-term via vaginal delivery. His temperature is 38.2°C (100.8°F) and his blood pressure is 90/42 mmHg. Physical examination shows a bulging fontanelle and nuchal rigidity. A CSF Gram stain demonstrates gram-positive cocci in chains.

(1)

(2)

(3)

(4)

DESCRIPTION

Gram-positive cocci in chains (1)

Alternative name: group B streptococcus (GBS)

INFECTIONS

PRIMARY

Congenital/neonatal

Nervous: meningitis

Respiratory: pneumonia

Systemic: bacteremia, sepsis

OTHER

Pregnant females

Renal/urinary: UTIs

Reproductive: chorioamnionitis, postpartum endometritis

Non-pregnant adults

Skin and soft tissue/musculoskeletal: cellulitis, ulcers, wounds, arthritis, osteomyelitis Systemic: bacteremia

PATHOGENESIS

Capsule

EPIDEMIOLOGY

May colonize gastrointestinal, genitourinary, or upper respiratory tract Transmission:

Displacement of endogenous strains Congenital/neonatal: vertical (perinatal)

DIAGNOSIS

Culture: catalase negative (2), beta-hemolytic (3), CAMP test positive—arrow head hemolysis (4). See also•3, Listeria monocytogenes•

PCR from rectal/vaginal swabs—used mainly for prenatal screening

PREVENTION

Vaginal cultures are obtained from pregnant women at 35 to 37 weeks’ gestation, and if GBS positive, IV antimicrobials are administered during delivery

TREATMENT

Penicillin G

Explanation: The three main bacterial pathogens that cause meningitis in newborns are Streptococcus agalactiae,•129, Escherichia coli•, and •3, Listeria monocytogenes•. Of these, only S. agalactiae is a gram-positive coccus in chains. Some pregnant women carry GBS in their GI tract or vagina, and can transmit the pathogen to the infant during parturition. Infections in newborns may be early onset (within 24 hours of birth) or late onset (4–5 weeks after birth) and include not only meningitis but pneumonia and sepsis as well.

6 Bunyavirus

Micro gem:

Most bunyaviruses are arthropod borne flavivirus (arboviruses) Arbovirus is not a true taxonomic classification. Instead, it encompasses viruses from multiple families. See also•10, Alphavirus•; •49, Colorado tick virus •

Vignette: A 4-year-old boy from Wisconsin returns from a week-long summer camping trip with his family with a fever. The following day he is still febrile and is now vomiting and also complains of a headache. His mother manages his symptoms with an analgesic and sends the boy to bed. The next day, the boy is lethargic and still febrile, so the mother takes him to emergency department. While there the boy has a seizure. His temperature is 39°C (102.2°F). Physical exam is remarkable for Babinski's sign. The boy's legs and arms contain several mosquito bites. A lumbar puncture is performed, and glucose is normal and protein is slightly elevated. The CSF Gram stain shows many mononuclear cells but no bacteria present. Serological analysis confirms the diagnosis.

DESCRIPTION

Taxonomy: Bunyavirus family

Virus properties: single-stranded, negative-sense RNA, enveloped, segmented genome

Clinically significant viruses (not a complete list):

Arbovirus: California serogroup viruses—California encephalitis virus (CEV) and LaCrosse virus (LV)

Hantavirus—which is not an arbovirus

INFECTIONS

PRIMARY

CEV and LV

Nervous: meningoencephalitis, encephalitis

Hantavirus

Systemic and respiratory: febrile illness followed by cardiopulmonary symptoms, hemorrhagic fever may occur

EPIDEMIOLOGY

CEV and LV

Transmission/vector: bite of a mosquito

Reservoir: rodents

Geographic distribution: North America

Hantavirus

Transmission: inhalation of contaminated aerosols from rodent (usually mice or rats) excreta

Geographic distribution: North and South America

DIAGNOSIS

Serology: antibody testing

PCR

TREATMENT

Supportive

Explanation: This boy has encephalitis caused by LaCrosse virus. This pathogen is part of the California serogroup viruses and part of the Bunyavirus family. Infections are transmitted via the bite of a mosquito. This infection may be seen in many regions of North and South America, but several cases have been recorded in the Midwest. Infections may be asymptomatic or present as encephalitis. Children are more likely to present with signs and symptoms of encephalitis, whereas adults tend be asymptomatic. The CSF may show elevated monocytic cells; however, no organisms will be seen with a Gram stain because this pathogen is a virus. Serological or molecular testing is necessary to confirm the diagnosis.

7 Arthropod Borne Flaviruses

Micro gem:

Most flaviviruses are arthropod borne viruses (arboviruses) Arbovirus is not a true taxonomic classification. Instead, it encompasses viruses from multiple families. Hepatitis C virus is a flavivirus but is NOT arthropod borne See also•91, Hepatitis C virus •; •10, Alphavirus•; •6, Bunyavirus •

Vignette: A 35-year-old woman travels from the United States to Thailand to visit her family. She stays for a month. Within 3 days of her return to the United States, she experiences a sudden onset of fever, chills, malaise, and headache. After 3 days of these symptoms, she visits the emergency department. In addition to her initial symptoms, she is now also experiencing joint and muscle pain. When questioned, she pinpoints her headache as severe pain behind her eye. Her temperature is 39.9°C (103.8°C). She is ill appearing, and a small, red macular rash is seen on her face and neck. WBCs, platelets, and sodium levels are decreased. Serology and reverse-transcriptase PCR confirms the causative agent.

DESCRIPTION

Taxonomy: Flavivirus family

Virus properties: single-stranded, positive-sense RNA, enveloped

Clinically significant viruses: Dengue, Japanese encephalitis, St.

Louis encephalitis, West Nile, Yellow fever, Zika

TREATMENT

Supportive

Explanation: This woman has Dengue. The classic signs and symptoms include high fever, retro-orbital pain, and an exanthem. Infections with this virus may present very similar to infections with Zika and Chikungunya which are also transmitted by mosquitos. Retro-orbital pain is more likely to be present in Dengue than in Zika and Chikungunya. Laboratory findings that are typical of infections with the Dengue virus include leukopenia, thrombocytopenia, and hypernatremia. There are four serotypes of Dengue. A person can be re-infected with any serotype more than once since the antibody response is not protective. Moreover, secondary infections are often more severe than the initial infection because of antibody-dependent enhancement. To date there is one vaccine available that targets all four serotypes of Dengue but it has not been approved for use in the United States.

8 Poliovirus

Vignette: A 6-year-old boy in a rural village in Afghanistan presents to a clinic because he has been unable to use is left leg for the past week. The child's arm is weak as well. The boy has not received routine childhood vaccines. Fecal samples are sent to a large hospital in the nearest city and found to be positive for poliovirus.

(1) Source: CDC public health library PHIL (phil.cdc.gov) image No. 5578 (http://phil.cdc.gov/phil/details_linked.asp?pid=5578)

DESCRIPTION

Taxonomy: Picornavirus family.

See also•140, Non-polio Enterovirus •; •89, Hepatitis A virus (HAV) •; •33, Rhinovirus •

Enterovirus genus (type C)

Virus properties: single-stranded, positive-sense RNA, non-enveloped

INFECTIONS

PRIMARY

Nervous: polio

Subclinical (majority of cases)

Minor illness

Nonparalytic poliomyelitis

Paralytic polio (1)

PATHOGENESIS

Paralytic polio: virus targets anterior horns of spinal cord and motor cortex of brain

EPIDEMIOLOGY

Transmission: fecal-oral

Polio is considered eradicated in most areas of the world. Geographic distribution: to date, endemic in areas of Afghanistan, Pakistan, and Nigeria.

DIAGNOSIS

Serology: antibody testing Viral culture

PREVENTION

Vaccination: inactivated vaccine and live attenuated (oral) vaccine

TREATMENT

Supportive

Explanation: As a result of effective vaccination efforts, polio has been eliminated from most countries. However, parts of Afghanistan, Pakistan, and Nigeria are still endemic. Major illness or paralytic polio is the least common form of polio but it is the most serious form of disease. This pathogen is part of the Picornavirus family, which includes enteroviruses such as coxsackie virus and rhinovirus and is transmitted via the fecal-oral route.