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Flashcards in Microbiology Bacteria - First Aid Deck (357):
1

Function of Peptidoglycan

gives rigid support, protects against osmotic pressure

2

Composition of Peptidoglycan

sugar backbone with peptide side chains cross-linked by transpeptidase

3

Cell wall/cell membrane (gram positives) function

major surface antigen

4

Cell wall/cell membrane composition

peptidoglycan for support; lipoteichoic acid that induces TNF and IL-1

5

Outer membrane (gram negatives) function

site of endotoxin (lipopolysaccharide (LPS)): major surface antigen

6

Outermembrane composition

Lipid A induces TNF and IL-1; O polysaccharide is the antigen.

7

Plasma membrane function

site of oxidative and transport enzymes

8

Plasma membrane composition

phospholipid bilayer

9

Ribosome function

protein synthesis

10

Ribosome composition

50S and 30S subunits

11

Periplasm function

space between the cytoplasmic membrane and outer membrane in gram negative bacteria

12

Periplasm composition

contains many hydrolytic enzymes, including beta-lactamases

13

Capsule function

protects against phagocytosis

14

Capsule composition

polysaccharide (except Bacillus anthracis which contains D-glutamate)

15

Pilus/fimbria function

mediate adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation

16

Pilus/fimbria composition

glycoprotein

17

Flagellum function

motility

18

Flagellum composition

protein

19

Spore function

resistant to dehydration, heat and chemicals

20

Spore composition

keratin-like coat; dipicolinic acid; peptidoglycan

21

Plasmid function

consists of a variety of genes for antibiotic resistance, enzymes and toxins

22

Plasmid composition

DNA

23

Glycocalyx function

mediates adherence to surfaces, especially foreign surfaces (indwelling catheters)

24

Glycocalyx composition

polysaccharide

25

Circular (coccus) gram positives

Staphylococcus
Streptococcus

26

Circular (coccus) gram negatives

Neisseria

27

Rod (bacillus) gram positives

Clostridium
Corynebacterium
Bacillus
Listeria
Mycobacterium (acid fast)
Gardnerella (gram variable)

28

Rod (bacillus) gram negative enterics

E. coli
Shigella
Salmonella
Yersinia
Klebsiella
Proteus
Enterobacter
Serratia
Vibrio
Campylobacter
Helicobacter
Pseudomonas
Bacteroides

29

Rod (bacillus) gram negative respiratory

Haemophilus (pleomorphic)
Legionella (silver)
Bordetella

30

Rod (bacillus) gram negative zoonotics

Francisella
Brucella
Pasteurella
Bartonella

31

Branching filamentous gram positive

Actinomyces
Nocardia (weakly acid fast)

32

Pleomorphic gram negatives

Rickettsiae (Giemsa)
Chlamydiae (Giemsa)

33

Spiral gram negatives

Borrelia (Giemsa)
Leptospira
Treponema

34

No cell wall

Mycoplasma (does not gram stain)

35

Mycoplasma contains...

sterols and has no cell wall.

36

Mycobacteria contains...

mycolic acid and has a high lipid content.

37

These bugs do not gram stain well:

Treponema
Mycobacteria
Mycoplasma
Legionella pneumophila
Rickettsia
Chlamydia

38

Treponema does not gram stain well becasue...

it is too thin to be visualized.

39

Mycobacteria does not gram stain well but its...

high lipid content in cell wall is detected by carbolfuchsin in acid-fast stain.

40

Mycoplasma does not gram stain well because...

it has no cell wall.

41

Legionella pneumophila does not gram stain well because...

it is primarily intracellular.

42

Rickettsia does not gram stain well because...

it is an intracellular parasite.

43

Chlamydia does not gram stain well becasue....

it is an intracellular parasite and lacks muramic acid in the cell wall.

44

Treponemes can be visualized with...

dark-field microscopy and fluorescent antibody staining.

45

Legionella can be visualized with...

silver stain.

46

Giemsa stain

Chlamydia
Borrelia
Rickettsiae
Trypanosomes
Plasmodium

(Certain Bugs Really Try my Patience)

47

PAS (periodic acid-Schiff) stain

stains glycogen, mucopolysaccharides

48

PAS stain is used to diagnose...

Whipple disease (Tropheryma whipplei).

49

Ziehl-Neelson (carbol fuchsin) stain

acid-fast organisms (Nocardia, Mycobacterium)

50

India Ink Stain

Cryptococcus neoformans (mucicarmine can also be used to stain the thick polysaccharide capsule red)

51

Silver stain

Fungi (Pneumocystis)
Legionella
Helicobacter pylori

52

Media used for H. influenzae

chocolate agar w/ factors V (NAD+) and X (hematin)

53

Media used for N. gonorrhea and N. meningitidis

Thayer-Martin (VPN) with Vancomycin, Polymyxin and Nystatin

54

In the VPN media, Vancomycin acts to...

inhibit gram-postitive organism. Polymyxin inhibits gram-negative except for Neisseria. And Nystatin inhibits fungi.

55

Media used for Bordetella pertussis

Bordet-Gengou (potato) agar

56

Media used for C. diptheriae

-Tellurite agar
-Loffler medium

57

Media used for M. tuberculosis

-Lowenstein-Jensen agar

58

Media used for M. pneumoniae

-Eaton agar, requires cholesterol

59

Media used for lactose fermenting enterics

pink colonies on MacConkey agar
(fermentation produces acid, turning the colony pink)

60

E. coli is also grown on...

eosin-methylene blue (EMB) agar as colonies with green metallic sheen.

61

Media used for Legionella

Charcoal yeast extract agar buffered with cysteine and iron

62

Media for fungi

Sabouraud agar

63

Obligate aerobes use...

O2-dependent system to generate ATP.

Examples include Nocardia, Pseudomonas aeruginosa and Mycobacterium tuberculosis.

64

Reactivation of M. tuberculosis (after immune compromise or TNF-alpha inhibitor use) has a predilection for...

the apices of the lung, which have the highest PO2.

65

P. aeruginosa is an aerobe seen in...

burn wounds, diabetes complications, nosocomial pneumonia and pneumonias in CF pts.

66

Examples of Obligate Anaerobes

-Clostridium
-Bacteroides
-Actinomyces

67

Obligate Anaerobes lack...

catalase and/or superoxide dismutase and are thus susceptible to oxidative damage.

68

Obligate Anaerobe general features

-foul smelling (short-chain fatty acids)
-difficult to culture
-produce gas in tissue (CO2 and H2)

69

Anaerobes are normal...

flora in the GI tract and pathogenic elsewhere.

70

The antibiotic that is ineffective against anaerobes is...

aminoglycosides because this antibiotic requires O2 to enter the bacterial cell.

71

Obligate intracellualar bugs are...

Rickettsia and Chlamydia because they can't make their own ATP.

72

Facultative intracellular bugs are...

Salmonella
Neisseria
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia

(Some Nasty Bugs May Live FacultativeLY)

73

Encapsulated Bacteria Examples

Strep pneumponiae
Haemophilus influenza
Neisseria meningitidis
Escherichia coli
Salmonella
Klebsiella pneumoniae
group B Strep

(SHiNE SKiS)

74

Capsule + protein conjugate serves as...

an antigen in vaccines.

75

Encapsulated bacteria are normally...

opsonized and then cleared by the spleen. Asplenics have decreased opsonizing ability and are at risk for severe infection.

76

All asplenics should receive...

s. pneumoniae, H. influenzae and N. meningitidis vaccines.

77

Catalase acts to...

degrade H2O2 before it can be converted to microbicidal products by myeloperoxidase.

78

People with chronic granulomatous disease (NADPH oxidase deficiency) have...

recurrent infections with catalase + organisms.

79

Examples of Catalase + organisms

Pseudomonas
Listeria
Aspergillus
Candida
E. coli
S. aureus
Serratia

(You need PLACESS for your cat.)

80

Some vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein, which....

enhances immunogenicity by promoting T-cell activation and subsequent class switching.

81

A polysaccharide antigen alone cannot be presented to...

T cells.

82

PCV

pneumococcal conjugate vaccine (Prevnar)

83

PPSV

pneumococcal polysaccharide vaccine with no conjugated protein (Pneumovax)

84

Hib and meningococcal vaccines are both...

conjugate vaccines.

85

Urease positive bugs

Cryptococcus
H. pylori
Proteus
Ureaplasma
Nocardia
Klebsiella
S. epidermidis
S. saprophyticus

(CHuck Norris hates PUNKSS)

86

Pigment producing bacteria

Actinomyces israeli
S. aureus
Pseudomonas aeruginosa
Serratia marcescens

87

Actinomyces produces pigment that is...

yellow "sulfur" granules whcih are composed of filaments of bacteria

88

S. aureaus produces a...

yellow pigment.

89

Pseudomonas aeruginosa produces a...

blue-green pigment.

90

Serratia marcescens produces a...

red pigment.

91

Protein A

binds Fc region of IgG; prevents opsonization and phagocytosis

92

Protein A is expressed by...

S. aureus.

93

IgA protease is...

an enzyme that cleaves IgA.

94

IgA protease is secreted by...

S. pneumoniae, Hib, and Neisseria in order to colonize respiratory mucosa.

95

M protein helps...

prevent phagocytosis and is expressed by group A strep.

96

Source of exotoxin

certain species of some gram-postivive and gram-negative bacteria

97

Source of endotoxin

outer cell membrane of most gram-negative bacteria

98

Chemistry of exotoxins

polypeptide

99

Chemistry of endotoxins

Lipopolysaccharide (structural part of bacteria, released when lysed)

100

location of genes of exotoxins

plasmid or bacteriophage

101

location of genes of endotoxins

bacterial chromosomes

102

toxicity of exotoxin

high

103

toxicity of endotoxin

low

104

clinical effects of endotoxin

fever, shock, DIC

105

Mode of action of endotoxin

induces TNF, IL-1 and IL-6

106

Antigenicity of Exotoxin

induces high-titer antibodies called antitoxins

107

Antigenicity of Endotoxin

poorly antigenic

108

Vaccines of exotoxins

toxoids used as vaccines

109

Vaccines of endotoxins

no toxoids formed and no vaccines available

110

Heat stability of exotoxins

destroyed rapidly at 60 C (except staph enterotoxin)

111

Heat stability of endotoxins

stable at 100 C for 1 hr

112

Typical diseases of exotoxins

Tetanus
Botulism
Diptheria

113

Typical diseases of endotoxins

Meningococcemia
Sepsis by gram-negative rodsCory

114

Corynebacterium diphtheriae exotoxin

Diphtheria toxin inactives elongationg factor 2 (EF-2) causing pharyngitis with pseudomembranes in the throat and severe lymphadenopathy (bull neck).

115

Pseudomonas aeruginosa exotoxin

Exotoxin A inactivates EF-2 leading to host cell death.

116

Shigella exotoxin

Shiga toxin inactivates 60S ribosome by removing adenine from rRNA leading to GI mucosal damage (dysentery); ST also enhances cytokine release (HUS).

117

EHEC exotoxin

Shiga-like toxin inactivate 60S ribosome by removing adening from rRNA leading to cytokine release (HUS).

118

EHEC is different from Shigella because...

it does not invade host cells.

119

ETEC exotoxins

Heat-labile toxin (LT)
Heat-stable toxin (ST)

120

ETEC LT toxin

overactivates adenylate cyclase (increase cAMP) leading to increaesd chloride secretion in the gut and H2O efflux

121

ETEC ST toxin

overactivates guanylate cyclase (increases cGMP) leading to decreased resorption of NaCl and H2O in the gut

122

Manifestation of ETEC exotoxins

Watery Diarrhea

123

Bacillus anthracis exotoxin

Edema factor mimics the adenylate cyclase enzyme (increases cAMP). This is likely responsible for edematous borders of black eschar in cutaneous anthrax.

124

Vibrio cholerae exotoxin

Cholera toxin overactivates adenylate cyclase by permanently activating Gs leading to increased chloride secretion in the gut and H2O efflux. Manifestation is voluminous "rice-water" diarrhea.

125

Bordetella pertussis exotoxin

Pertussis toxin overactivates adenylate cyclase (increased cAMP) by disabling Gi, impairing phagocytosis to permit survival of the microbe.

126

Manifestation of the pertussis toxin

whooping cough: child coughs on expiration and "whoops" on inspiration

127

Clostridium tetani exotoxin

Tetanospasmin cleaves SNARE proteins required for NT release. Toxin prevents release of inhibitory (GABA and glycine) from Renshaw cells in the spinal cord.

128

Manifestation of the Tetanospasmin toxin

-spasticity
-risus sardonicus
-lockjaw

129

Clostridium botulinum exotoxin

Botulinum toxin cleaves SNARE proteins required for NT release. Prevents release of stimulatory (ACh) signals at NMJs leading to flaccid paralysis.

130

Manifestations of Botulinum toxin

-flaccid paralysis
-floppy baby

131

Diptheria toxin, Exotoxin A, Shiga toxin, Shiga-like toxin, Heat-labile toxin, Cholera toxin and Pertussis toxin are all...

ADP ribosylating A-B toxins. The B component binds to host cell surface receptor enabling endocytosis. The A component attaches ADP-ribosyl to disrupt host cell prtoeins.

132

Clostridium perfringens exotoxin

Alpha toxin is a phospholipse (lecithinase) that degrades tissue and cell membranes.

133

Manifestation of Clostridium perfringens alpha toxin

degradation of phospholipids leads to myonecrosis ("gas gangrene") and hemolysis ("dobule zone" of hemolysis on blood agar)

134

Streptococcus pyogenes exotoxin

Streptolysin O is a protein that degrades cell membranes

135

Manifestation of Streptolysin O

lyses RBCs
contributes to beta-hemolysis
host antibodies against toxin (ASO) are used to diagnose rheumatic fever

136

Staphylococcus aureus exotoxin

Toxic shock syndrome toxin (TSST-1) brings MHC II and TCR in proximity to the outside of an antigen binding site to cause an overwhelming release of IFN-gamma and IL-2 leading to shock.

137

Manifestation of TSST-1 and Exotoxin A

Toxic shock syndrome: fever, rash, shock

138

Other toxins of Staph aureus cause...

scalded skin syndrome (exfoliative toxin) and food poisoning (enterotoxin).

139

Strep pyogenes exotoxin

Exotoxin A brings MHC II and TCR in proximity to the outside of an antigen binding site to cause overwhelming release of IFN-gamma and IL-2 leading to shock.

140

Tranformation

ability to take up DNA from the environment; seen in S. pneumoniae, Hib and Neisseria

141

F+ x F- Conjugation

F+ plasmid contains genes required for sex pilus and conjugation. Bacteria without this plasmid are termed F-. Plasmid (dsDNA) is replicated and transferred through the pilus from the F+ cell. There is no transfer of chromosomal genes.

142

Hfr x F- conjugation

F+ plasmid can become incorporated into bacterial chromosomal DNA, termed high-frequency recombination (Hfr) cell. Replication of incorporated plasmid DNA may include some flanking chromosomal DNA. Transfer of plasmid and chromosomal genes.

143

Transposition

Segment of DNA (transposon) that can "jump" can transfer genes from plasmid to chromosome and vice versa.

144

Examples of transposition include...

antibiotic resistance gene on R plasmid.

145

Generalized transduction

Lytic phage infects bacterium leading to cleavage of bacterial DNA. Parts of bacterial chromosomal DNA becom packaged in viral capsid. Then the phage infects another bacterium, transferring the genes.

146

Specialized transduction

Lysogenic phage infects bacterium; viral DNA incorporates into bacterial chromosome. When phage DNA is excised, flanking bacterial genes may be excised with it. DNA is then packaged into phage viral capsid and can infect another bacterium.

147

Genes for the following 5 bacterial toxins are encoded in a lysogenic phage:

ABCDE
1. ShigA-like toxin
2. Botulinum toxin
3. Cholera toxin
4. Diphtheria toxin
5. Erythrogenic toxin of S. pyogenes

148

Novobiocin sensitivity

Staph saprophyticus is resistant.
Staph epidermidis is sensitive.

149

Optochin sensitivity

Strep viridans is resistant.
Strep pneumoniae is sensitive.

150

Bacitracin sensitivity

group B strep are resistant
group A strep are sensitive

151

Alpha-hemolytic bacteria form...

a green ring around colonies on blood agar

152

Alpha-hemolytic bacteria include:

Strep pneumoniae
Viridans strep

153

Beta-hemolytic bacteria form...

a clear area of hemolysis on blood agar.

154

Beta-hemolytic bacteria include...

Staph aureus
Strep pyogenes
Strep agalactiae
Listeria

155

Staphylococcus aureus features

-gram positive cocci in clusters
-Protein A (binds Fc-IgG, inhibiting complement activation and phagocytosis)
-commonly colonizes the nose

156

Staph aureus causes (3):

1. inflammatory disease
2. Toxin-mediated disease
3. MRSA infection

157

Inflammatory diseases of Staph aureus

-skin infections
-organ abcesses
-pneumonia (often after virus infxn)
-endocarditis
-osteomyelitis

158

MRSA infection is an important cause of...

serious nosocomial and community acquired infections; resistant to methicillin and nafacillin because of altered penicillin binding protein (PBP).

159

Use of vaginal or nasal tampons predisposes to...

toxic shock syndrome.

160

S. aureus food poisonin is due to...

ingestion of a preformed toxin (that is not destroyed by cooking). Short incubation (2-6 hrs).

161

S. aureus is able to form a...

fibrin clot around itself leading to abscess.

162

Staphylococcus epidermidis infects...

prosthetic devices and IV catheters by producing adherrent biofilms

163

S. epidermidis is a normal part of...

skin flora and can contaminate blood cultures.

164

Staphylococcus saprophyticus is the second most common cause of...

uncomplicated UTI in young women.

165

Streptococcus pneumoniase is the most common casue of:

1. Meningitis
2. Otitis media
3. Pneumonia
4. Sinusitis

166

Strep pneumoniae features

-lancet-shpaed, gram-positive diplococci
-encapsulated
-IgA protease

167

Pneumococcus is associated with...

rusty sputum
sepsis in sickle cell anemia
splenectomy

168

Strep pneumoniae has no virulence without..

its capsule.

169

Viridans strep features

-alpha-hemolytic
-normal flora of the oropharynx

170

Viridans group strep causes...

dental caries (S. mutans)
bacterial endocarditis (S. sanguinis)

171

S. sanguinis makes...

dextrans which bind to fibrin-platelet aggregates on damaged heart valves.

172

Streptococcus pyogenes (Group A) causes...

pyogenic, toxigenic and immunologic diseases.

173

Pyogenic diseases of S. pyogenes

-pharyngitis
-cellulitis
-impetigo

174

Toxigenic diseases of S. pyogenes

-scarlet fever
-toxic shock-like syndrome
-necrotizing fasciitis

175

Immunologic diseases of S. pyogenes

-rheumatic fever
-acute glomerulonephritis

176

Antibodies to M protein enhance...

host defenses against S. pyogenes but can give rise to rheumatic fever.

177

Recent S. pyogenes infection is detected by...

ASO titer.

178

JONES criteria for Rheumatic Fever

Joints (polyarthritis)
<3 (carditis)
Nodules (subcutaneous)
Erythema marginatum
Sydenam chorea

179

Impetigo more commonly precedes...

glomerulonephritis than pharyngitis.

180

Scarlet Fever

scarlet rash w/ sandpaper-like texture; strawberry tongue, circumoral pallor

(caused by S. pyogenes)

181

Streptococcus agalactiae (group B) features

-beta-hemolytic
-colonizes the vagina
-causes pneumonia, meningitis and sepsis mainly in babies
-Hippurate test +

182

S. agalactiae produces...

CAMP factor which enlarges the area of hemolysis formed by S. aureus.

183

Pregnant pts with a positive screen for S. agalactiae at...

35-37 wks should receive intrapartum penicillin prophylaxis.

184

Enterococci (group D strep) features

-normal colonic flora
-penicillin G resistant
-cause UTI, biliary tract infections and subacute endocarditis

185

Lancefield grouping of streptococci is based on...

differences in the C carbohydrate on the bacterial cell wall.

186

VRE (vancomycin-resistant enterococci) are an important cause of...

nosocomial infection.

187

Lab test for enterococci

can grow in 6.5% NaCl and bile

188

Streptococcus bovis (group D streptococci)

colonizes the gut; can cause bacteremia and endocarditis in colon cancer pts

189

Bovis in the blood =

cancer in the colon

190

Corynebacterium diphtheriae causes...

diphtheria via exotoxin encoded by Beta-prophage.

191

Symtpoms of diptheria

-pseudomembranous pharyngitis (grayish-white membrane)
-lymphadenopathy
-myocarditis
-arrhythmias

192

Lab diagnosis of C. diphtheriae is based on...

gram-positive rods with metachromatic (blue and red) granules and Elek test for toxin.

(shaped like a club)

193

Diphtheria can be prevented with...

a toxoid vaccine.

194

C. diphtheriae show black colonies on...

cystine-tellurite agar.

195

Some bacteria can form spores at the end of the...

stationary phase when nutrients are limited.

196

Spores features (3)

-highly resistant to heat and chemicals
-have dipicolinic acid in their core
-no metabolic activity

197

To kill spores, you must...

autoclave them by steaming at 121 C for 15 min.

198

Spore forming gram positive bacteria found in soil (3)

1. Bacillus anthracis
2. Clostridium perfringens
3. Clostridium tetani

199

Other spore formers inlcude (3):

1. B. cereus
2. C. botulinism
3. Coxiella burnetii

200

Clostridia features (3)

-gram positive
-spore forming
-obligate anaerobic bacteria

201

C. tetani produces...

tetanospasmin, an exotoxin causing tetanus.

202

Tetanus is...

tetanic paralysis (blocks glycine and GABA release from Renshaw cells in the spinal cord). Causes spastic paralysis, trismus (lockjaw) and risus sardonicus.

203

C. botulinism causes disease in adults by...

ingestion of a preformed toxin. In babies, ingestion of spores in honey causes the disease.

204

C. difficile produces...

2 toxins:
1. Toxin A (enterotoxin) binds to the brush border of the gut.
2. Toxin B (cytotoxin) causes cytoskeletal disruption via actin depolymerization leading to pseudomembranous colitis and diarrhea.

205

C. diff often occurs secondary to...

antibiotic use (esp. clindamycin and ampicillin).

206

C. diff is diagnosed by...

detection of one or both of the toxins in the stool.

207

Tretment for C. diff

Metronidazole or Oral Vancomycin

(fecal transplant may prevent relapse in recurring infxns)

208

Bacillus anthracis features (4):

1. gram positive
2. spore-forming rod
3. produces anthrax toxin (causing anthrax)
4. only bacterium with a polypeptide capsule (contains D-glutamate)

209

Cutaneous anthrax

A boil like lesion leads to an ulcer with black eschar (painless, necrotic). This can but rarely leads to bacteremia and death.

210

Pulmonary anthrax

Inhalation of spores leads to flu-like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis and shock.

211

Woolsorter's disease

inhalation of anthrax spores from contaminated wool

212

Bacillus cereus causes...

food poisoning. Spores survive cooking in rice (and pasta). Keeping rice warm results in germination of spores and enterotoxin formation.

213

2 Types of B. cereus food poisoning

1. Emetic type (nausea/vomiting within 1-5 hrs, caused by cereulide (a preformed toxin))
2. Diarrheal type (watery, nonbloody diarrhea and GI pain w/i 8-18 hrs)

214

Listeria monocytogenes is a...

facultative intracellular microbe. It is the only gram-positive bacteria to produce LPS.

215

Listeria monocytogenes forms...

"rocket tails" via actin polymerization that allow them to move through the cytoplasm and into the cell membrane, thereby avoiding abtibody. Characteristic tumbling motility.

216

Listeria monocytogenes is acquired by...

ingestion of unpasteurized dairy products an deli meats, via transplacental transmission or vaginal transmission during birth.

217

Listeria monocytogenes causes:

1. amnionits
2. septicemia
3. spontaneous abortion
4. granulomatosis infantiseptica
5. neonatal meningitis
6. meningitis in immunocompromised pts
7. mild gastroenteritis

218

Treatment for Listeria

Ampicillin in infants, immunocompromised pts and the elderly in empiric tx of meningitis.

219

Both Actinomyces and Nocardia form...

long, branching filaments resembling fungi.

220

Actinomyces features

1. gram positive anaerobe
2. normal oral flora
3. causes oral/facial abcesses that drain through sinus tracts and form yellow "sulfur granules"
4. treat with penicillin

221

Nocardia features

1. gram positive aerobe
2. acid fast (weak)
3. found in soil
4. causes pulmonary infxns in immunocompromised and cutaneous infections after trauma in immunocompetent
5. treat with sulfonamides

222

Pts will be PPD+ for TB if...

they have a current infxn, past exposure or BCG vaccinated.

223

Pts will be PPD- for TB if...

they have no infxn or are anergic (steroids, malnutrition, immunocompromised) and in sarcoidosis.

224

A more specific test for TB is...

an interferon gamma release assay (IGRA) which has fewer false positives from the BCG vaccine.

225

Mycobacterium kansasii causes...

pulmonary TB-like symptoms.

226

Mycobacterium avium-intracellulare causes...

disseminated, non-TB disease in AIDS pts; give prophylactic treatment with Azithromycin.

227

TB symptoms include...

fever, night sweats, weight loss and hemoptysis.

228

Virulent strains of mycobacterium have...

cord factor which inhibits macrophage maturation and induces release of TNF-alpha.

Sulfatides (surface glycolipids) inhibit phagolysosomal fusion.

229

Leprosy (Hansen Disease) is caused by...

Mycobacterium leprae, an acid-fast bacillus that likes cool temperatures (infects skin and superficial nerves).

230

Lepromatous form of Hansen Disease

presents diffusely over the skin with leonine facies and is communicable; characterized by low cell-mediated immunity with a humoral Th2 response.

231

Tuberculoid form of Hansen Disease

limited to a few hypoesthetic, hairless skin plaques; characterized by high cell-mediated immunity w/ a largely Th1 immune response

232

Treatment for Leprosy

Tuberculoid form: Dapsone and Rifampin for 6 months
Lepromatous form: Dapsone, Rifampin, Clofazimine for 2-5 yrs

233

Examples of Lactose-fermenting enteric bacteria (5)

1. Citrobacter
2. Klebsiella
3. E. coli
4. Enterobacter
5. Serratia (weak fermenter)

234

E.coli produces...

Beta-galactosidase, which breaks down lactose into glucose and galactose.

235

On EMB agar, lactose fermenters grow as...

purple/black colonies. E.coli also has a green sheen.

236

Gram-negative bacilli are resistant to...

penicillin G but may be susceptible to penicillin derivatives such as ampicillin and amoxicillin.

237

Gram-negative bacilli are resistant to penicllin G and vancomycin because...

the outer membrane layer inhibits entry of the drugs.

238

Neisseria features

-gram negative diplococci
-ferment glucose
-produce IgA protease
-N. gonorrhea is often intracellular (w/i neutrophils)

239

Neisseria gonococci features

-sexually transmitted
-causes gonorrhea, septic arthritis, neonatal conjuctivitis, PID and Fitz-Hugh-Curtis syndrome

240

Neonatal transmission of N. gonorrhae can be prevented with...

erythromycin ointment.

241

Treatment for N. gonorrhae

Ceftriaxone + (azithromycin or doxycycline) for possible chlamydia coinfection

242

Neisseria menigococci features

-polysaccharide capsule
-maltose fermentation
-vaccine
-respiratory and oral secretions
-causes meningococcemia and meningitis and waterhouse-friderichsen syndrome

243

N. meningitidis can be prevented in close contacts with...

rifampin, ciprofloxacin or ceftriaxone prophylaxis.

244

Treatment for N. meningitidis

Ceftriaxone or Penicillin G

245

Haemophilus influenzae features

-small, gram negative rod
-aerosol transmission
-produces IgA protease A

246

Haemophilus influenzae causes...

Epiglottitis (cherry red/thumbprint sign)
Meningitis
Otitis media
Pneumonia

247

H. influenzae mucosal infections can be treated with...

Amoxicillin +/- Clavulanate.

248

Hib meningitis can be treated with...

ceftriaxone. And Rifampin can be given to close contacts for prophylaxis.

249

The H. influenzae vaccine contains...

type B capsular polysaccharide (polyribosylribitol phosphate) conjugated to diphtheria toxoid. Given between 2 and 18 months of age.

250

H. influenzae does not cause...

the flu. The influenza virus does.

251

Legionella pneumophila features

-gram-negative rod
-use silver stain
-grow on charcoal yeast extract culture with iron and cysteine

252

Transmission of Legionella pneumophila

Aerosol transmission from environmental water source habitat (air conditioning, hot water tanks). No person-to-person transmission.

253

Legionella pneumophila is detected clinically by...

presence of antigen in the urine.

254

Treatment for Legionella

Macrolide or Quinolone

255

Labs for Legionella show...

hyponatremia.

256

Legionella causes...

Legionnaires' disease and Pontiac fever.

257

Pontiac Fever is...

a mild flu-like syndrome.

258

Legionnaire's disease is...

severe pneumonia, fever, GI and CNS symptoms

259

Pseudomonas aeruginosa features

-aerobic, gram-negative rod
-non lactose fermenting
-oxidase +
-produces pyocyanin (blue-green pigment)
-grape-like odor
-water source
-produces endotoxin and exotoxin A

260

Pseudomonas is associated with:

wound and burn infections
pneumonia (esp. CF)
Sepsis
external otitis (swimmer's ear)
UTI
Drug use
Diabetic Osteomyelitis
hot tub folliculitis
Ecthyma gangrenosum

261

Ecthyma gangrenosum is...

a rapidly progressive, necrotic cutaneous lesion caused by Pseudomonas bacteremia. Typically in immunocompromised pts.

262

Treatment for pseudomonas aeruginosa

aminoglycoside plus extended spectrum penicillin

263

Chronic pneumonia in CF pts is associated with...

biofilm from pseudomonas.

264

E. coli virulence factors (and what they cause)

1. fimbrae - cystitis and pyelonephritis
2. K capsule - pneumonia and neonatal meningitis
3. LPS endotoxin - septic shock

265

EIEC mechanism

microbe invades intestinal mucosa and causes necrosis and inflammation (similar manifestations to Shigella)

266

EIEC presentation

dysentery

267

ETEC mechanism

produces heat-labile and heat-stable enterotoxins. no inflammation or invasion

268

ETEC presentation

travelere's diarrhea (watery)

269

EPEC mechanism

no toxin produced; adheres to apical surface, flattens villi, prevents absorption

270

EPEC presentation

diarrhea (usually in children)

271

EHEC mechanism

O157:H7 is the most common serotype. produces shiga-like toxin that causes HUS (triad of anemia, thrombocytopenia and acute renal failure). Microthrombi form on the endothelium damaged by the toxin leading to mechanical hemolysis (schistocytes) and decreased renal blood flow.; microthrombi consume platelets leading to thrombocytopenia.

272

EHEC presentation

dystentery

273

EHEC is distinguished from other forms of E. coli because...

it does not ferment sorbitol.

274

Klebsiella features

-mucoid colonies caused by abundant polysaccharide capsules
-red "currant jelly" sputum
-intestinal flor

275

Klebsiella causes...

lobar pneumonia in alcoholics and diabetics when aspirated. (abscesses in lungs and liver)

Can also cause nosocomial UTIs.

276

Salmonella features

-flagella
-disseminate hematogenously
-many animal reservoirs
-produces hydrogen sulfide
-does not ferment lactose

277

Antibiotics for salmonella may...

prolong fecal excretion of the organism.

278

Salmonella acts by...

invading intestinal mucosa and causing a monocytic response sometimes leading to bloody diarrhea.

279

Shigella features

-cell to cell transmission
-human and primate reservoirs
-does not ferment lactose

280

Abitibotics for shigella may...

shorten the duration of fecal excretion of the organism.

281

Shigella acts by...

invading intestinal mucosa and causing PMN infiltration often leading to bloody diarrhea.

282

Salmonella typhi causes...

typhoid fever characterized by red spots on the abdomen, fever, HA and diarrhea.

283

Salmonella typhi can remain in the...

gallbladder and cause a carrier state.

284

Campylobacter jejuni is a major cause...

of bloody diarrhea.

285

Campylobacter is transmitted...

fecal-orally through foods such as poultry, meat and unpasteurized milk.

286

Features of Campylobacter jejuni

-comma or S-shaped
-oxidase +
-grows at 42 C

287

Campylobacter is a common antecedant to...

Guillain-Barre Syndrome and reactive arthritis.

288

Vibrio cholerae produces...

rice-water diarrhea via enterotoxin that permanently activates Gs (increasing cAMP). Prompt oral rehydration is necessary.

289

Vibrio cholerae features

-comma shaped
-oxidase +
-grows in alkaline media
-endemic to developing countries

290

Yersinia enterocolitica is usually transmitted from...

pet feces, contaminated milk or pork.

291

Yersinia enterocolitica causes...

mesenteric adenitis that can mimic Chron's or appendicitis.

292

Helicobacter pylori causes...

gastritis and peptic ulcer (esp. duodenal).

293

H. pylori is a risk factor for...

peptic ulcer, gastric adenocarcinoma and lymphoma.

294

H. pylori features

-curved, gram negative rod
-catalase +
-oxidase +
-urease +
-creates an alkaline environment

295

Most common initial treatment for H. pylori is...

proton pump inhibitor + Clarithromycin + either amoxicillin or metronidazole

296

Spirochetes are...

spiral-sharped bacteria with axial filaments and include Borrelia, Leptospira and Treponema.

297

Of the spirochetes, only Borrelia can be visualized using...

aniline dyes (Wright or Giemsa stain) in light microscopy.

298

Treponema is visualized by...

dark-field microscopy.

299

Leptospira interrogans is found in...

water contaminated with animal urine and causes leptospirosis: flu-like symptoms, jaundice, photophobia with conjunctival suffusion (erythema without exudate).

300

Leptospira interrogans is prevalent among...

surfers and in the tropics (Hawaii).

301

Weil Disease

severe form of leptospirosis with jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage and anemia

302

Lyme disease is caused by..

Borrelia burgdorferi which is transmitted by the tick Ixodes. Natural reservoir is the mouse.

303

Initial symptoms of lyme disease

-erythema chronicum migrans
-flu like symptoms
+/- facial nerve palsy

304

Later symptoms of lyme disease

-monoarthritis
-migratory polyarthritis
-AV nodal block
-encephalopathy
-facial nerve palsy
-polyneuropathy

305

Treatment for Lyme Disease

Doxycycline, Ceftriaxone

306

Syphlis is caused by...

the spirochete Treponema pallidum.

307

Primary syphilis

a localized diseae presenting with painless chancre

308

Serologic testing for primary and secondary syphilis

VDRL/RPR (non-specific)
Confirm w/ specific test (FTA-ABS).

309

Secondary syphilis

disseminated disease with constitutional symptoms, maculopapular rash (palms and soles), condylomata lata

310

Tertiary syphilis

Gummas (chronic granulmoas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis "general paresis"), Argyll Robertson pupil

311

Signs of Tertiary syphilis

-broad-based ataxia
-positive Romberg
-Charcot joint
-stroke w/o HTN

312

To diagnose tertiary syphilis, test...

spinal fluid with VDRL or RPR.

313

Congenital syphilis signs

-saber shins
-saddle nose
-CN VIII deafness
-Hutchinson teeth
-mulberry molars

314

To prevent congenital syphilis:

treat mother early in pregnancy bc transmission usually occurs after the 1st trimester

315

Argyll Robertson pupil

constricts with accommodation but is not reactive to light
(associated with tertiary syphilis)

316

VDRL detects...

nonspecific antibody that reacts with beef cardiolipin; it is sensitive for syphilis but not specific.

317

VDRL has many false positives due to...

viral infection (mono, hepatitis)
drugs
rheumatic fever
SLE

318

Jarisch-Herxheimer rxn

flu-like syndrome after antibiotics are started - due to killed bacteria releasing pyrogens

319

Anaplasma is a zoonotic bacteria that causes...

anaplasmosis from ixodes ticks.

320

Bartonella is a zoonotic bacteria that causes...

cat scratch disease, bacillary angiomatosis from cat scratches.

321

Borrelia recurrentis is a zoonotic bacteria that casues...

relapsing fever from louse.

322

Brucella is a zoonotic bacteria that causes...

Brucellosis/undulant fever from unpasteruized dairy.

323

Chlamydophila psittaci is a zoonotic bacteria that causes...

Psittacosis from parrots and other birds.

324

Coxiella burnetii is a zoonotic bacteria that causes...

Q fever from aerosols of cattle/sheep amniotic fluid.

325

Ehrlichia chaffeensis is a zoonotic bacteria that causes..

Ehrlichiosis from Lone Star ticks.

326

Francisella tularensis is a zoonotic bacteria that causes...

Tularemia from ticks, rabbits and deer fly.

327

Pasteurella multocida is a zoonotic bacteria that causes...

cellulitis and osteomyelitis from animal bites, cats and dogs.

328

Rickettsia prowazekii is a zoonotic bacteria that causes...

epidemic typhus from louse.

329

Rickettsia rickettsii is a zoonotic bacteria that causes...

Rocky Mountain spotted fever from dermacentor ticks.

330

Rickettsia typhi is a zoonotic bacteria that causes...

endemic typhus from fleas.

331

Yersinia pestis is a zoonotic bacteria that causes....

plague from fleas.

332

Gardnerella vaginalis is a...

pleomorphic rod that presents with vaginosis as a gray vaginal discharge with a fishy smell; nonpainful.

333

Gardnerella is associated with...

sexual activity but is not sexually transmitted.

334

Bacterial vaginosis is also characterized by....

overgrowth of certain anaerobic bacteria in the vagina.

335

In bacterial vaginosis, under the microscope....

clue cells, or vaginal epithelial cells covered with the Gardnerella bacteria are visible.

336

Treatment for Gardnerella vaginalis

Metronidazole (or Clindamycin to treat anaerobic bacteria).

337

Treatment for all Rickettsial disease and vector-borne illnesses is...

Doxycycline.

338

Rocky Mountain Spotted Fever occurs primarily in...

the South Atlantic States (esp. North Carolina). Rash starts at wrists and ankles and spreads to trunk, palms, soles.

(caused by Rickettsia rickettsii)

339

Rickettsiae features

-obligate intracellular
-need CoA and NAD+ because they cannot synthesize ATP

340

Classic Triad of Rocky Mountain Spotted Fever

-headache
-fever
-rash

341

Typhus rash starts...

centrally and then spreads out, sparing the palms and soles.

342

Ehrlichiosis

-monocytes with moulae (berry-like inclusions) in cytoplasm
-rash is rare

343

Anaplasmosis

-granulocytes with morulae in cytoplasm
-rash is rare

344

Q fever

-presents as pneumonia
-rash is rare
-no arthropod vector

345

Chlamydiae features

-cannot make their own ATP
-obligate intracellular
-cause mucosal infections

346

2 forms of Chlamydiae:

1. Elementary body (small, dense): infectious, enters cell via endoctyosis and transforms into reticulate body
2. Reticulate body: replicates in cell by fission; reorganizes into elementary body

347

Chlaymdia trachomatis causes...

reactive arthritis (Reiter syndrome), follicular conjunctivitis, urethritis and PID.

348

C. pneumoniae and C. psittaci cause...

atypical pneumonia; transmitted by aerosol.

349

Treatment for Chlamydiae

Aziththromycin or Doxycycline

350

The chlamydial cell wall is unusal in that it...

lack muramic acid.

351

Chlamydia trachomatis types A, B and C

chronic infection, cause blindness due to follicular conjunctivitis in Africa

352

Chlamydia trachomatis types D-K

urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis

353

Chlamydia trachomatis typse L1, L2 and L3

Lymphogranuloma venereum - small, painless ulcers on genitals; swollen, painful inguinal LNs that ulcerate

354

Mycoplasma pneumoniae is the classic cause of...

atypical "walking" pneumonia (insidious onset, HA, nonproductive cough, patchy or diffuse interstital infiltrate).

355

Atypical pneumonia findings

-X-ray looks worse than pt
-high titer of cold agglutinins (IgM)
-grown on Eaton agar
-more common in pts less than 30
-frequent outbreaks in miliatry recruits and prisons

356

Treatment for Mycoplasma pneumoniae

-macrolide
-doxycycline
-fluoroquinolone

357

Mycoplasma pneumoniae features

-no cell wall (thus, penicillin is ineffective)
-not seen on gram stain
-bacterial membrane contains sterols for stability