Micro Midterm2 Flashcards Preview

Micro First Half > Micro Midterm2 > Flashcards

Flashcards in Micro Midterm2 Deck (351):
1

How is a diagnosis for M. pneumoniae made?

Usually clinically

2

Can penicillins and cephalosporins be used to treat M. pneumoniae?

No, because it has no cell wall

3

Which antibiotics are used to treat M. pneumoniae?

Macrolides and tetracyclines

4

In an older patient, is Chlamydophila pneumonia more likely to produce a lower or an upper respiratory tract infection?

Lower

5

How many adults in the U.S. get Chlamydophila pneumoniae per year?

~100k

6

How is C. pneumoniae transmitted?

Respiratory droplets

7

Does C. pneumoniae have a cell wall?  Does it replicate extracellularly or intracellularly?

Intracellularly

8

What is an "elementary body" of C. pneumoniae?

It is a metabolically inactive, infectious form that can survive outside a host cell

9

What is the intracellular form of C. pneumoniae called?

Reticulate body

10

Why does C. pneumoniae evade host defenses so well?

Replicating intracellularly, it can evade host detection

11

Is there a higher risk of C. pneumoniae in immunocompromised patients as compared to immunocompetent patients?

It is unclear

12

What is the annoying symptom of C. pneumoniae that persists for weeks?

A cough that does not subside

13

Does C. pneumoniae typically cause a fever?

No

14

Which age group is most likely to get an asymptomatic C. pneumoniae infection?

Children

15

Symptomatic vs. asymptomatic C. pneumoniae might be associated with the host's inflammatory predisposition, which could be implied by what vascular condition?

Atherosclerosis

16

Do most cases of C. pneumoniae result in a diagnosis?

No

17

Which antibodies can be detected after C. pneumoniae infection that can diagnose its presence?

IgM and IgG antibodies

18

What is the third-most common cause of atypical pneumonia?

Legionella pneumophila

19

Is Legionella spread from person to person?

No

20

Where does L. pneumophila prefer to live?

Aqueous habitats, both fresh and saltwater

21

How does L. pneumophila transfer from a water source to a person's respiratory tract?

Aerosolization of the water by e.g. a shower head

22

What is the incubation period of L. pneumophila?

2-10 days

23

Why is L. pneumophila an underreported disease?

Generalized typical pneumoniae is often treated with azythromycin, which can also be effective against L. pneumophila, so doctors typically do not end up distinguishing between this and typical pneumonia

24

What is the shape, size, and gram staining of L. pneumophila?

Small, gram-negative bacilli

25

Is L. pneumophila an anaerobe or an aerobe?

Obligate aerobe

26

Which serogroup of L. pneumophila causes 75%-90% of human infections?

Group 1

27

Does Legionella pneumophila grow on typical bacterial culturing media?

No, it requires special media

28

What organism is this, which is growing well on buffered charcoal agar?  Is this a medium that a lab would typically include in a culture assay?

Legionella; no, this is atypical media

29

What phagocytoses L. pneumophila when they reach the lungs?

Alveolar macrophages

30

Can L. pneumophila be deadly?  Is there a neutrophil response, or a humoral response, or both?  What dying cells trigger a severe inflammatory response?

Yes; both responses occur; dying macrophages

31

Of the top three atypical pneumonias, which is the most dangerous?

Legionella pneumophila

32

How can L. pneumophila be diagnosed by lab tests?

Culture of respiratory secretions on selective media, and detection of antigen of serogroup 1 (e.g. via direct fluorescence with antibodies)

33

What are the mainstays of treatment for L. pneumophila?

Macrolides (azythromycin), tetracyclines, and quinolones

34

Does L. pneumophila replicate intracellularly or extracellularly? How does this affect choice of treatment?

Intracellularly; antibiotics that reach an effective intracellular concentration must be used

35

Do clarithromycin and azythromycin require the bacterium to have a cell wall?

No, they block protein synthesis (they are both macrolides)

36

What are the three most frequent toxic effects of macrolides?

Diarrhea, nausea, abdominal pain

37

What is the common suffix for fluroquinolone antibiotics?  Do they inhibit DNA, RNA, protein, or cell wall synthesis?

-floxacin; inhibit DNA synthesis (topoisomerase and gyrase inhibition)

38

Can treatment for atypical pneumonia be administered orally?

Yes

39

How might liver function or kidney function affect choice of a fluoroquinolone?

Levofloxacin and ciprofloxacin are eliminated by the kidneys, while moxifloxacin is eliminated by the liver in bile

40

What is the most common clinical symptom for a GI infection?

Diarrhea

41

Do most infections of the GI tract causing diarrhea require hospitalization?

No

42

What are the big four bacterial pathogens for foodborne diarrheal disease?

Vibrio, campylobacter, shigella, salmonella

43

What strain of E. coli is particularly significant for diarrheal disease?

E. coli O157

44

What is the only gram-positive bacterium that causes common diarrheal disease?

Listeria

45

What are the top two identified bacterial pathogens causing GI disease hospitalization in New York?

Campylobacter and Salmonella

46

What are the three mechanisms for enteric infection?

Inflammatory (invasion w/ cytotoxin), noninflammatory (adherence w/ cytotoxin), and penetrating

47

Which bacterial pathogen has the smallest infectious dose? What about the second smallest?

Shigella (100); Campylobacter (1000)

48

What is the order of magnitude difference between an infectious dose of Salmonella as opposed to Campylobacter?

103 greater for Salmonella (106 cells typical infectious dose)

49

What is a typical infectious dose for E. coli or Vibrio cholerae?

108 cells

50

What dangerous symptom does cholera cause via an exotoxin?

Dehydration by diarrhea and vomiting of clear fluid

51

What bacterium causes cholera and has "cholera" in the species name?

Vibrio cholerae

52

When was the last epidemic of cholera in the US?

1911

53

What is the shape of V. cholerae?  What is its gram staining?  Does it have spores?

Curved to straight bacilli; gram negative; no spores

54

Which serotypes of V. cholerae cause cholera?

O1 and O139

55

What is the natural environmental habitat of cholera?

Aquatic environments

56

What are the non-life-threatening clinical symptoms of cholera, besides diarrhea and vomiting?

Muscle cramps, loss of skin turgor

57

How does death occur for a cholera patient?

Hypovolemic shock, metabolic acidosis, and uremia from tubular necrosis

58

What is the chemical activity of cholera toxin?  What receptor does it act upon? What intracellular signaller is upregulated, causing loss of cell nutrients?

It is an A-B type ADP-ribosylating toxin; Ganglioside receptor; cAMP

59

Are antibiotics needed to treat V. cholerae?

No, just rehydration

60

Is Shigella lactose-fermenting?

No

61

Besides bloody diarrhea, what are two other clinical hallmarks of bacillary dystentery?

Abdominal cramps and pain, and tenesmus (painful straining to pass stool)

62

What does tenesmus mean?

Painful straining to pass stool

63

What is the reservoir of infectious Shigella?

Humans, it is transmitted person-to-person

64

What is the pathogenetic mechanism of Shigella infection?

It invades enterocytes and causes cell death

65

What does subunit A of the Shiga toxin do?  What about subunit B?

It permanently inactivates ribosomes; it binds to host receptors

66

Do organisms beside Shigella produce shiga-like toxins?

Yes, some strains of E. coli

67

Is bacteremia a common complication of Shigella?

No

68

What are the two species of Salmonella that cause enteric disease?

Salmonella enterica and Salmonella bongori

69

What is the shape and gram staining of Salmonella?  Are they aerobic?  Are they motile?  Do they form spores?

Gram-negative rods; anaerobic; motile; non-spore-forming

70

Do Salmonella species produce hydrogen sulfide during fermentation?

Yes

71

Can Salmonella cause bacteremia?  What complication typified by rose spots and delirium can result from salmonella infection?

Yes; typhoid fever

72

Are there asymptomatic carriers of Salmonella?

Yes, including some that had to be forcibly quarantined

73

How long does it take for symptoms of Salmonella to present after infection?

48h

74

What is the shape of Salmonella incidence in the US from year to year?

Spikey because of sporadic outbreaks

75

What are three common sources of Salmonella infection besides person-to-person contact?

Agricultural products, processed food, and domestic animals

76

What two cell types are invaded by Salmonella during initial stages of infection?

M cells and intestinal macrophages

77

How does Salmonella interact with microvilli on certain enterocytes to facilitate endocytosis?  Can it invade non-phagocytic cells?

It attracts them, surrounding itself with the cell's membrane; yes, it can invade many kinds of enterocytes

78

What areas of the Salmonella genome contribute most to its virulence?

Two pathogenicity islands called SPI1 and SPI2

79

How does Salmonella survive inside the cell after phagocytosis?

It secretes toxins that prevent fusion of lysosomes with the endosome and then replicates in the endosome

80

How does Salmonella release its anti-lysosomal fusion toxins into the cytoplasm despite being trapped in an endosome after endocytosis?

Toxins secreted by salmonella (encoded on the pathogenicity island SPI-2) move to the endosomal membrane and allow transport into the cytoplasm of SPI-2 effector molecules

81

What is this spirally bacterium that causes enteric symptoms, mainly through the handling of chicken?

Campylobacter

82

What is the shape and gram staining of Campylobacter?

Helical, gram-negative

83

What is Guillain-Barré syndrome? What is the most common antecedent infection?

An autoimmune disorder that causes peripheral paralysis after foreign antigens cause mistargeting of the immune response toward nerve tissues; Campylobacter

84

What pathogen is this, causing gastric and duodenal ulcers?

H. pylori

85

The stomach can normally handle acidity with its mucosal lining, but what happens during H. pylori infection that causes ulceration?

The bacterium invades intercellularly, using secreting toxins to disrupt cell-to-cell junctions

86

Are most infections for H. pylori symptomatic?

No

87

What is the most common cause for gastritis, gastric ulcer, and duodenal ulcer?

H. pylori infection

88

What upper gastric infection that commonly causes gastritis or ulceration is linked to gastric adenocarcinoma?

H. pylori

89

Can non-selective stool cultures diagnose H. pylori?

No, it is an upper GI infection and it is hard to isolate on non-selective media

90

What needs to be added to culture to get proper growth of H. pylori from a stool sample?

Bile salts

91

What tests can distinguish between Salmonella and other enterobacteriaceae?

Citrate and ornithine decarboxylase

92

What three antibiotic resistances are common with the top four bacterial causes of GI infection?

Amoxicillin (or penicillins), 1st generation cephalosporins, and trimethoprim-sulfamethoxazole

93

Since GI bacterial infections are resistant to many antibiotics, which ones are actually used for treatment?

Fluroquinolones (-floxacins), 3rd generation cephalosporins (ceftriaxone), and macrolides (azithromycin)

94

Does daptomycin have gram-negative activity?  Why or why not?

No; it cannot penetrate the outer membrane sufficiently to cause depolarization

95

What are the most common manifestations of Klebsiella infection?

Pneumonia, UTI, and nosocomial infections

96

How can E. coli be distinguished from K. pneumoniae in the lab, e.g. after a urine sample for a UTI manifestion?

E. coli is indole positive, K. pneumoniae is negative

97

What is the main reservoir of K. pneumoniae?

The lower GI tract of humans, and secondarily the skin and female genital tract

98

What media is used here to demonstrate K. pneumoniae and E. coli by the fermentation of lactose?

MacConkey agar, which gives pink colonies

99

Is K. pneumoniae motile or non-motile? Is it encapsulated?

Non-motile; encapsulated

100

What kind of intra-abdominal infections are caused by K. pneumoniae?

Liver abscesses, peritonitis, and cholangitis

101

What is the variant of pneumonia caused by K. pneumoniae called?  What is the characteristic type of sputum produced?

Friedländer's disease; "currant jelly"

102

Is K. pneumoniae a common infection for immunocompetent hosts?

No

103

What is the mortality of a K. pneumoniae infection?

Up to 50%

104

Why does the sputum produced in a K. pneumoniae infection look like currant jelly?

The infection is hemorrhagic and necrotizing

105

What feature of this CXR is consistent with the typical qualities of K. pneumoniae infection?

Propensity for upper lobes

106

After E. coli or Streptococcus, what is the next most common bacterium causing acute inflammation of the peritoneum (peritonitis)?

K. pneumoniae

107

After E. coli, what is the next most common organism isolated in UTIs?

K. pneumoniae

108

Features that distinguish complicated UTIs from uncomplicated UTIs include renal [...], emphysematous pyelonephritis, and catheter-associated UTIs.

Features that distinguish complicated UTIs from uncomplicated UTIs include renal abscesses, emphysematous pyelonephritis, and catheter-associated UTIs.

109

Features that distinguish complicated UTIs from uncomplicated UTIs include renal abscesses, emphysematous [...], and catheter-associated UTIs.

Features that distinguish complicated UTIs from uncomplicated UTIs include renal abscesses, emphysematous pyelonephritis, and catheter-associated UTIs.

110

Features that distinguish complicated UTIs from uncomplicated UTIs include renal abscesses, emphysematous pyelonephritis, and [...]-associated UTIs.

Features that distinguish complicated UTIs from uncomplicated UTIs include renal abscesses, emphysematous pyelonephritis, and catheter-associated UTIs.

111

Can K. pneumoniae cause skin and skin structure infections?

Yes

112

What antibiotic are K. pneumoniae almost universally resistant to due to a chromosomal gene encoding an enzyme breaking down the antibiotic?

Ampicillin (and other penicillins)

113

Which penicillins are effective against Pseudomonas and Klebsiella?  What are they often combined with?

Anti-pseudomonal penicillins which include piperacillin, ticarcillin, and carbenicillin; a β-lactamase inhibitor

114

Which generation(s) of cephalosporins would be used against K. pneumoniae?

3rd or 4th generations, usually cefepime (4th generation)

115

Does cefepime have activity against gram negatives, gram positives, or both?

Both

116

How many β lactamases are there?

Thousands

117

Are ESBL and KPC chromsomal inducible or plasmid-mediated β-lactamases?

Plasmid-mediated

118

Which β-lactams are reserved for the most sick patients, particularly those with infections from ESBL-containing bacteria?

Carbapenems

119

What kind of drug is imipenem-cilastatin?

A carbapenem (β-lactam antibiotic)

120

What is distinctive about this β-lactam structure?  What class is it?

It lacks a ring; it is a monobactam

121

What is the one monobactam clinically available in the US?  Is it active against gram negatives, gram positives, or both? Is it effective against aerobic or anaerobic organisms?

Azteronam; Gram negatives only; Aerobes only

122

Can monobactams be hydrolyzed by ESBL?

Yes

123

What is ESBL?  When was it first spotted?

It is "extended spectrum β-lactamase", which confers resistance against all β-lactams except carbapenems; in the 1980's

124

If a K. pneumoniae strain is resistant to ceftriaxone but susceptible to imipenem, what kind of β-lactamase does it most likely have?

ESBL

125

When were variants of K. pneumoniae resistant to carbapenems first discovered?  What plasmid-mediated β-lactamase do they typically have?

1990's; KPC (K. pneumoniae carbapenemase)

126

Are there other known methods of K. pneumoniae resistance to carbapenems besides KPC?

Yes

127

What fraction of hospital-detected K. pneumoniae in New York State is carbapenem-resistant?

21%, significantly higher than the rest of the US

128

Which three other countries are considered endemic or epidemic for carbapenem-resistant K. pneumoniae?

Israel, China, and Greece

129

What treatment options remain for somebody with carbapenem-resistant K. pneumoniae?

Polymyxin, tygacil, and gentamicin

130

What is the mechanism of polymyxins? Are they effective against gram-negatives, gram-positives, or both?

They are cationic agents that bind to the outer membrane disrupting its integrity; only gram-negatives

131

What tissues cannot be penetrated by polymyxins?

Lungs and CSF (cannot cross BBB)

132

What two toxicities are significant with polymyxins?

Nephrotoxicity and neurotoxicity

133

What is the mechanism of tigecycline?  What class of bacteria is it indicated for treating?

It is similar to tetracyclines, as it inhibits protein synthesis, but resistance to tigecycline is less common than for tetracyclines; effective against gram-negative bacilli like K. pneumoniae

134

What drug class can be attempted to treat a gram-negative infection in a patient with a severe β-lactam allergy?

Monobactams e.g. aztreonam

135

What structural component of K. pneumoniae is the most important virulence factor?

Polysaccharide capsule

136

Is imipenem a cure-all for multidrug-resistant gram-negative infections?

No, carbapenem resistance is on the rise (especially in New York State)

137

Which species of anaerobic gram positive bacilli is most commonly seen in the hospital?

Clostridium difficile

138

What organism is most often linked with antibiotic-associated diarrhea?

Clostridium difficile

139

Which Clostridium causes spastic paralysis? Which causes flaccid paralysis?

C. tetani: spastic;C. botulinum: flaccid

140

Are there many anaerobic bacteria that are normal human commensals?

Yes

141

When mixed with aerobic organisms, what do anaerobes tend to form?

Abscesses

142

Do anaerobes produce gas when they metabolize food?

Yes

143

What is crepitus?

When you push on necrotic tissue and you feel bubbles created by an infectious disease

144

What antibiotic can be used against most anaerobic infections?

Penicillin, or penicillin with a β-lactamase inhibitor

145

Besides penicillins, what four other antibiotics are used to treat anaerobic bacterial infections?

2nd generation cephalosporins, carbapenems, metronidazole, and clindamycin

146

What is the mechanism of action of metronidazole?

DNA damage

147

What dietary modifications are necessary when taking metronidazole?

No alcohol

148

What is the mechanism of clindamycin?

It inhibits the translocation step of bacterial peptide synthesis

149

A 63 yo woman receives prophylactic cefazolin before surgery for a hip fracture, and develops fever, abdominal pain, and severe diarrhea.  Her WBC is elevated and a colonoscopy is performed.  What bacterium is most suspect?

Clostridium difficile

150

Does C. difficile form spores? What is its shape and gram staining?

Yes, it forms spores; it is a gram-positive bacillus

151

What are three lab tests can be used to make a diagnosis of C. difficile?

EIA toxin assay, cytotoxicity assay, and PCR

152

What two toxins of Clostridium difficile are detected by PCR?

Toxin A and B, the former is an enterotoxin and the latter is a cytotoxin.

153

What characterizes a toxic megacolon? What surgical procedure may be required for it?

A massive dilation of the colon and septic shock; it may require a bowel resection

154

What are the standard treatments for C. difficile?

Metronidazole and oral vancomycin

155

Why can oral vancomycin treat C. difficile even though it is poorly absorbed by the gut?

C. difficile is a GI infection, and oral vancomycin can act locally on the GI tract without being absorbed

156

What could allow for C. difficile to survive a course of antibiotics and reappear during a relapse?

Spore formation

157

What mutation has created hypervirulent strains of C. difficile?

They have lost the repressor region of a toxin gene

158

What is the average cost of each case of C. difficile-associated disease?

>$3.6k

159

Will alcohol-based sanitizers remove C. difficile spores from one's hands?

No

160

What problem results from using gram stains to distinguish C. perfringes?

It doesn't always retain the gram stain, so it may not appear positive even though it is gram positive

161

What kind of hemolysis is distinctive for C. perfringens?

Double zones, one with complete hemolysis, and one with partial hemolysis

162

What does the India Ink prep reveal about C. perfringens?

The capsule

163

What toxin causes the zone of complete hemolysis by C. perfringens? What about the partial hemolysis?

Theta toxin: complete hemolysis;Alpha toxin: partial hemolysis

164

Can C. perfringens cause soft tissue infections? What about bacteremia?

Yes to both

165

What is emphysematous cholecystitis?  Which Clostridium species can cause it?

Infection of the gall bladder; C. perfringens

166

The third leading cause of food poisoning, after Campylobacter and Salmonella, is...?

Clostridium perfringens

167

What is the clinical timecourse for C. perfringens GI infection?

24-48 hours

168

What are two chief symptoms of C. perfringens infection?

Abdominal cramps and watery diarrhea

169

What antibiotic is used to treat C. perfringens enteric infection?

Penicillin

170

What toxin does Clostridium tetani release that causes spastic paralysis and this type of lockjaw?  What is this lockjaw called?

Tetanospasmin; risus sardonicus (sardonic smile)

171

Clostridium botulinum is associated with what kind of foods?

Improperly canned foods

172

What kind of neurologic disorder results from the AB toxin released by C. botulinum?

Flaccid paralysis

173

When a gas is present in a CT scan of infected tissues, what class of organisms can be immediately suspected?

Anaerobic gram-positive bacilli

174

What forms when commensal flora of the mouth are allowed to enter a normally sterile space?  When anaerobic fermentation leads to production of gas, inflating tissues of the neck and compressing the airway, what is this condition called?

Abscesses; Ludwig's angina

175

What organism is suggested by a liver abscess growing an anaerobic Gram-negative bacillus?

Bacteroides fragilis

176

What is the shape and gram staining of Bacteroides fragilis? What enzymes allow it to tolerate oxygen?

Pleomorphic gram negative rod; Catalase and superoxide dismutase

177

Actinomyces infections can be characterized by what kind of substance that is excreted through the skin?

Sulfur granules, which are actual colonies of the organism

178

What is the shape and gram staining of of Actinomyces?

Gram positive branching filamentous rod (bacillus)

179

Where are Actinomyces often found throughout the oral cavity?

In molar tooth cavities

180

What is the appearance of Nocardia under the gram stain?  What stain with a modified pH is used to distinguish it?

Beaded filaments (left); acid fast stain (right)

181

Is Nocardia a symptomatic infection in immunocompetent hosts?

No

182

Which bacterium is this, visualized with an acid fast stain?

Nocardia

183

Which two infectious organisms are both characterized as branching gram positive bacilli?  What growth condition can be used to distinguish them?  What stain can be used to distinguish them?

Actinomyces and Nocardia; Nocardia can grow aerobically, whereas actinomyces cannot; Nocardia can be stained with acid fast, whereas Actinomyces is not

184

What is Nocardia treated with?

Trimethoprim-sulfamethoxazole

185

What gram-positive beaded and fast-growing bacillus is identified with surgical wound infections?

Mycobacterium fortuitum

186

Does M. fortuitum grow faster or slower than M. tuberculosis?

Faster

187

What is the gram staining and shape of M. fortuitum?

Gram positive, bacillus

188

How is M. fortuitum infection of a surgical wound treated?

Debridement, macrolides and β lactams

189

What gram positive bacillus (preventable with vaccines) can produce an exotoxin that leads to airway constriction and death? What vaccine provides immunity against it?

Corynebacterium diphtheriae; DTaP

190

The DTaP vaccine protects against tetanus, pertussis, and what other bacterial infection?

Cornyebacterium diphtheriae, causing diphtheria

191

Is diphtheria common in industrialized nations?

No, not after widespread vaccination programs

192

How is Corynebacterium diphtheriae treated?

Antitoxin

193

What organism can cause fatal gas gangrene?

C. perfringes

194

What does "zoonotic" mean with regard to infections?

Zoonotic means that the pathogen is primarily transmitted to humans from animals

195

What is the characteristic symptom of diphtheria?

A swollen neck

196

What organism, causing petechial rashes and altered mental status, is seen in this slide?

N. meningitidis

197

Is N. meningitidis gram-positive or gram-negative?  What is its shape?

Gram-negative; cocci

198

Why does C. difficile sometimes present in the hospital after prophylactic administration of antibiotics, e.g. cefazolin?

The antibiotics kill the normal gut flora, allowing the C. difficile to replicate without competition

199

What commonly eaten food is particularly susceptible to Listeria colonization when stored at improper temperatures?

Soft cheeses

200

What is the primary infective route of L. monocytogenes?

The intestinal epithelium, via an ingested substance

201

What organism causes spotted fevers (e.g. Rocky Mountain spotted fever) and various types of typhus?

Rickettsia species

202

What organism causes human monocytic ehrlichiosis (HME)?

Ehrlichia chaffeensis

203

What organism causes anaplasmosis?

Anaplasma phagocytophilum

204

What bacterium causes Lyme disease?

Borrelia burgdorferi

205

What organism is this, which is shown microscopically and with the characteristic rash from infection?

Borrelia burgdorferi

206

What is the typical shape of a rash for Lyme disease?

Bullseye

207

In early and late Lyme disease, what heart condition can manifest?

AV block, possibly causing bradycardia

208

What joint conditions present with long-term Lyme disease?

Swelling and arthritic-like symptoms

209

What insect is this?  What bacterium does this kind of insect spread?

Black legged tick; B. burgdorferi

210

Where is Lyme disease most common?

Northeastern US and the region around Wisconsin

211

During what time of year is Lyme disease most likely spread from ticks to humans?

The fall

212

What animal is the primary host that blacklegged ticks (that carry Lyme disease) feed from?

Deer

213

Which stage of life of the blacklegged tick is most likely to spread B. burgdorferi to humans?

Nymph, which is after larva and before adult

214

When are most cases of Lyme disease reported throughout the year?

In a unimodal distribution centered around July

215

What bacterium is this rash typical of?

B. burgdorferi (Lyme disease)

216

What is the medical term for the "bullseye rash" caused by B. burgdorferi?

Erythema migrans

217

During which timecourse after infection are Lyme disease symptoms mostly localized to the site of the tick bite?

3-30 days

218

1-4 months after a bite containing B. burgdorferi, what general change in the localization of symptoms occurs?

They become more systemic, involving the nervous system, heart, and the rash is disseminated

219

What two nervous system disorders can result 1-4 months after infection with B. burgdorferi?

Cranial nerve palsy and lymphocytic meningitis

220

What two signs of cardiac involvement in Lyme disease can occur 1-4 months after the tick bite?

Heart block or myocarditis

221

What does this patient have?  How long has he had it?

Lyme disease (B. burgdorferi); 1-4 months (rash is disseminated)

222

What are chronic symptoms of late Lyme disease?  When do they begin?

Intermittent arthritis and vague neurological symptoms, like radicular pain, paresthesias, and Lyme encephalopathy; 4 months to years after the bite

223

What is the best way to diagnose Lyme disease?  Why?

Clinical picture; antibody and PCR lab tests are not yet reliable, and culturing and staining techniques are not able to demonstrate the organism well

224

What kind of lab tests are available for Lyme disease?  Are they reliable for diagnosis?

IgG and IgM antibody tests and PCR; no, they are not reliable

225

Why is doxycycline not typically given to children under 8?

It has the potential to stain the teeth (incorporation into anything that is being calcified)

226

What is the typical course of antibiotics for non-critical manifestations of Lyme disease? What if there is heart block or meningitis?

Amoxicillin for non-critical cases; ceftriaxone for hospitalized cases

227

What is this bacterium, found in docs and raccoons and potentially transmitted to humans?

Leptospirosis

228

Which organ systems are affected by leptospirosis?

Liver, kidney, skin, and brain

229

How does leptospirosis enter the body?

Broken skin or mucosa followed by contact with the organism (e.g. from an infected dog or raccoon)

230

How is leptospirosis treated?  What does the first phase of symptoms present as?  What is the source of infection?

Penicillin; flu-like symptoms; animals

231

Are Rickettsia gram positive or gram negative?

Gram negative

232

Do Rickettsia species replicate extracellularly or intracellularly?

Intracellularly

233

What is the reservoir for Rickettsia?

Hard ticks

234

What disease does R. rickettsii cause that has a 23% case fatality rate?

Rocky Mountain spotted fever

235

Where is the greatest concentration of the cases of Rocky Mountain spotted fever within the US?

The American Southeast

236

What are classic clinical manifestations of Rocky Mountain spotted fever?

Fever, headache and rash

237

What tick-borne disease causes this rash?

Rocky Mountain Spotted Fever (R. rickettsii)

238

How does Rickettsia induce its own phagocytosis? How does it escape from the phagosome?

By triggering actin rearrangement; release of phospholipase

239

What food-borne organism is R. rickettsii similar to in terms of how the cells propel themselves and spread to adjacent cells?

L. monocytogenes

240

Is humoral immunity, cell-based immunity, or both required to clear R. rickettsii?  Why?

Cell-based; the organism is mostly confined intracellularly so antibodies cannot bind it directly

241

What is the shape and gram staining of Ehrlichia and Anaplasma? Do they grow inside or outside of host cells?

Both are tiny round gram negative bacteria; they grow intracellularly

242

Do Ehrlichia break out of the phagosome after phagocytosis?

No, they tend to stay within the phagosome

243

Which kind of immune cell is targeted by Ehrlichia chafeensis? Which is targeted by Anaplasma phagocytophillum?

E. chafeensis: monocytes;A. phagocytophillum: granulocytes

244

What kind of insect carries E. chafeensis and A. phagocytophilum?

Ticks

245

Which other tick-borne disease is carried by the same species of tick that is the reservoir for Lyme disease?

Anaplasma phagocytophilum

246

Do rickettsia, ehrlichiosis and anaplasmosis patients present reliably with knowledge of a tick bite?

No, they do not recall one in 40% of cases

247

Of rickettsia, ehrlichiosis, and anaplasmosis, which is least likely to produce a rash? Which is most likely?

Least likely, anaplasmosis; Most likely, rickettsia

248

What are the symptoms common to rickettsia, ehrlichiosis, and anaplasmosis?

Fever, headaches, myalgia, and malaise

249

What is the incubation period for rickettsia, ehrlichiosis, and anaplasmosis?

5-10 days

250

What is the treatment for rickettsia, ehrlichiosis, and anaplasmosis? Should confirmation from the lab be obtained before starting treatment?

Doxycycline; no

251

What type of lab test can identify rickettsia, ehrlichiosis, and anaplasmosis before the infection runs its course?

PCR (on either infected tissue or blood)

252

Following a tick bite, should you cover it with petroleum jelly to make it detach itself?

No, you should use tweezers to remove it as soon as possible

253

What bacterium causes "cat-scratch disease"?

Bartonella henselae

254

What is the manifestation of cat-scratch disease in a immunocompetent host?  What about in an immunocompromised person?

Lymphadenopathy in an immunocompetent person; bacillary angiomatosis (rashes) in immunocompromised

255

What is the etiology for this kind of rash following a cat scratch?  Is it more likely in immunocompetent or immunocompromised patients?

B. henselae infection has caused small tumors in the endothelium of small vessels; immunocompromised patients

256

What is visualized in a biopsy of a B. henselae related lymphadenopathy?

Granulomas and possibly the organism

257

What is the shape and gram staining of B. henselae?

Gram negative bacilli

258

Is B. henselae associated with older or younger cats?

Usually younger cats

259

What organism causes Q Fever?

Coxiella burnetii

260

What is the reservoir for C. burnetii?

Cattle, sheep, and goats

261

How is C. burnetii transmitted from cattle, sheep, or goats to humans? What cell type is infected?

Via inhalation; macrophages

262

Can you culture C. burnetii?

No, it is a biohazard

263

How can brucellosis be contracted?

Ingestion of dairy products or contaminated hands, or skin abrasion and contact with infected animals

264

What common symptom characterizes exposure to C. burnetii and brucellosis?  What is the typical source of these pathogens?

Mysterious fevers and myalgia; farm animals like cattle, goats, and sheep

265

What is the best way to diagnostically confirm most tick-borne diseases? Is it practical to do this before starting treatment?

Serology; no, because serology takes two weeks and some tick-borne diseases are rapidly fatal

266

What condition are these symptoms immediately indicative of?

Scarlet fever

267

How is scarlet fever usually treated? What is the most serious side effect?

Penicillin; allergic reaction

268

A patient that is treated for scarlet fever now presents with this rash.  What is most likely to have occurred?

Allergic reaction to penicillin

269

Which antibiotic has a characteristic adverse effect of bile sludging?

Ceftriaxone

270

Which antibiotic has the characteristic adverse effect of ototoxicity?

Aminoglycosides

271

Which antibiotics have the characteristic adverse effect of QTc prolongation?

Azithromycin, fluoroquinolones

272

Which antibiotic has the characteristic side effect of tendonitis?

Fluoroquinolones

273

A 2 yo boy presents with 2 days of refusal to walk and fever of 39.5°C. What is the most likely infectious organism? Is this a serious infection? What antibiotic should be used?

S. aureus (most important cause of septic arthritis);yes;vancomycin (not nafcillin or ceftriaxone, in case it is MRSA)

274

Which is the only cephalosporin activate against MRSA?

Ceftaroline, a 5th generation cephalosporin

275

What outpatient (oral) antibiotics are often active against MRSA?

Clindamycin, doxycycline, and trimethoprim-sulfamethoxazole

276

What treatment for MRSA can cause myositis or creatinine phosphokinase elevation?

Daptomycin

277

Which treatment for MRSA has 100% bioavailability?  What is its drawback?

Linezolid; besides side effects like bone marrow suppression or serotonin syndrome, it is costly

278

Which treatment for MRSA can cause Red Man syndrome?

Vancomycin

279

When a serious S. aureus infection, should a clinician wait until its susceptibility to methicillin is determined before treating?

No, assume it is MRSA and treat accordingly (vancomycin, daptomycin, linezolid, ceftaroline) 

280

An infant presents with fever, lethargy, with no immunizations and a stiff neck.  WBC count is elevated and mostly neutrofils, with WBCs present in CSF. What is this infection called?  What is the initial treatment until the organism is isolated?

Meningitis; vancomycin and ceftriaxone

281

From 1 month old throughout adulthood, what are the top three suspects for bacterial meningitis? What is the empirical treatment?

Neisseria meningitidis, S. pneumoniae, and H. influenzae type B; ceftriaxone and vancomycin

282

What additional cause of meningitis must be suspected in an immunocompromised patient?  What antibiotic should be added to the regimen to combat it?

Listeria; ampicillin

283

Until the age of 1 month, what are the typical suspects for a bacterial meningitis?

Group B streptococcus, E. coli, and Listeria

284

Which generation of cephalosporins is needed to treat the CNS?

Third generation: ceftriaxone, cefotaxime, ceftazidime

285

Which β-lactams can be used against pseudomonas?

Cefepime (4th generation cephalosporin), piperacillin-tazobactam (no CNS penetration), carbapenems such as imipenem, azteronam, ceftazidime (3rd generation cephalosporin)

286

Can Pseudomonas be treated with fluroquinolones?

Yes

287

What fluoroquinolone is effective against gram negatives and gram positives, including anaerobes?

Moxifloxacin

288

What is the empiric treatment for a enterococci infection in a patient with neutropenia due to AML? What drug will be used instead if susceptibility is discovered?

Vancomycin, or if resistance is suspected, linezolid and daptomycin; ampicillin

289

What drugs can be used to treat a C. difficile colitis?

Metronidazole and secondarily oral vancomycin

290

Are intra-abdominal abscesses going to contain one species, or multiple species?  What is the typical pair of antibiotics used?

Multiple; cephalosporin + metronidazole

291

What is the difference in treatment between typical (community-acquired, lobar) pneumonia and atypical pnemonia?

Typical pneumonia, if treated as an inpatient, uses ceftriaxone and potentially vancomycin if S. aureus is suspected; they are treated similarly as outpatients (azithromycin and levofloxacin)

292

How many cases of sepsis are diagnosed per year?  How many of them result in death?

750,000; 31%

293

What is the mainstay of treatment for a patient with severe inflammatory response syndrome?

Fluids (normal saline bolus)

294

Why is oxygen provided to a patient undergoing sepsis?

Oxygen delivery is impaired, e.g., by lack of functional surface area of the alveoli

295

Out of all the bacterial vaccines that are administered in the US, which has been the least successful in terms of % reduction?

Pertussis (82% reduction)

296

What federal body sets policy on vaccines?

CDC Advisory Committee on Immunization Practices

297

Can children under the age of 2 develop memory immunity in response to a polysaccharide antigen?

No

298

What is the minimum human lethal dose of tetanospasmin? What bacterium produces it?

2.5 ng/kg; Clostridium tetani

299

What is the difference between an adjuvant and a conjugate vaccine?

A conjugate is the attachment of a protein antigen to create a T dependent response to a normally T independent antigen like a carbohydrate, creating longer-term immune system memory, whereas an adjuvant simply stimulates a nonspecific immune response concurrent with the vaccine antigen exposure

300

What is the most common route of vaccine administration?

Intramuscular (deltoid or anterolateral thigh)

301

What two types of immune response are elicited by a mucosal administration of a vaccine?

Systemic and mucosal (IgA) response

302

What are two methods of mucosal administration of a vaccine?

Oral or intranasal

303

Are vaccines for the plague and Lyme disease commonly administered today?  What about anthrax and tularemia?

No, plague and Lyme disease vaccines are discontinued; anthrax and tularemia vaccines are only given to military personnel

304

What can be done over time to increase the magnitude and duration of antibody response to a vaccine?

Booster doses

305

The top four presenting bacterial STD's are [...], chlamydia, gonorrhea, and chancroid.

The top four presenting bacterial STD's are syphilis, chlamydia, gonorrhea, and chancroid.

306

The top four presenting bacterial STD's are syphilis, [...], gonorrhea, and chancroid.

The top four presenting bacterial STD's are syphilis, chlamydia, gonorrhea, and chancroid.

307

The top four presenting bacterial STD's are syphilis, chlamydia, [...], and chancroid.

The top four presenting bacterial STD's are syphilis, chlamydia, gonorrhea, and chancroid.

308

The top four presenting bacterial STD's are syphilis, chlamydia, gonorrhea, and [...].

The top four presenting bacterial STD's are syphilis, chlamydia, gonorrhea, and chancroid.

309

Which STDs increase the risk for HIV transmission and why?

STDs that create ulcerative lesions (e.g. syphilis, herpes and chancroid) increase the risk of HIV transmission because of greater exposure between partners of blood-accessible fluids

310

What bacterium causes syphilis?

Treponema pallidum

311

High risk groups for syphilis are: men who have sex with men, drug users, and [...]

High risk groups for syphilis are: men who have sex with men, drug users, and those with multiple sexual partners.

312

High risk groups for syphilis are: [...], drug users, and those with multiple sexual partners.

High risk groups for syphilis are: men who have sex with men, drug users, and those with multiple sexual partners.

313

High risk groups for syphilis are: men who have sex with men, [...], and those with multiple sexual partners.

High risk groups for syphilis are: men who have sex with men, drug users, and those with multiple sexual partners.

314

What coats the spirochetes of T. pallidum and protects against phagocytosis?

Host cell fibronectin

315

Is syphilis a localized or systemic disease?  Are most of the symptoms related to toxins released by T. pallidum or the immune response?

Secondary syphilis is systemic, because the spirochete disseminates into the bloodstream; the immune response creates most symptoms

316

What is the prototypical lesion of syphilis?  What does it look like?

The chancre; painless, smooth ulcer with firm borders and clean base.

317

Why might a patient with syphilis not recognize that they have the chancre (lesion) signalling infection?

It is painless, heals on its own in 3-6 weeks, and may be in an internal or hard to see (perianal, intravaginal) area.

318

What STD is this lesion prototypical of? What organism causes it? How long does it take for this lesion to heal on its own?

Syphilis; T. pallidum; 3-6 weeks

319

What kind of a lesion is this? What organism is suspect?

Chancre; T. pallidum (causing syphilis)

320

What is the shape of T. pallidum?

Spirochete

321

What are differential diagnoses (related diagnoses that must be ruled out) for a primary chancre that looks like syphilis (T. pallidum)?

Chancroid (H. ducreyi), lymphogranuloma venereum, herpes, and trauma

322

During secondary syphilis, what clinical manifestations can occur?

Many possible symptoms: rash, fever, malaise, weight loss, diffuse painless lymphadenopathy, pharyngitis, arthralgia, uveitis...

323

Which STD infection has a secondary stage that this rash a classical sign for?

Syphilis: palm and sole rash

324

Does the rash of secondary syphilis only occur on the palms and soles?

No, it can also appear on the trunk and elsewhere on the skin

325

If a patient is asymptomatic for syphilis but as immunoreactivitity to anti-treponemal antibodies, should an LP be taken check for CNS involvement?

This is controversial, so usually it is not done unless the immunoreactivity is very high

326

What are common symptoms of late syphilis?

Aortitis, CNS complications, and gumma formation

327

Can T. pallidum be grown on culture?  How is it typically visualized?

No; it can be visualized on darkfield microscopy from scrapings of chancres, mucus, or condylomata lata

328

Is there a treponemal antibody test?

Yes

329

What is the primary treatment for syphilis?  Is there any substitute for this drug in the late stages of the disease?

Penicillin; no

330

Syndromes of Chlamydia trachomatis that present clinically are: [...] infection, infant pneumonia, conjunctivititis, and ocular trachoma.

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant pneumonia, conjunctivititis, and ocular trachoma.

331

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant [...], conjunctivititis, and ocular trachoma.

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant pneumonia, conjunctivititis, and ocular trachoma.

332

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant pneumonia, [...], and ocular trachoma.

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant pneumonia, conjunctivititis, and ocular trachoma.

333

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant pneumonia, conjunctivititis, and ocular [...].

Syndromes of Chlamydia trachomatis that present clinically are: genital infection, infant pneumonia, conjunctivititis, and ocular trachoma.

334

What is the most common bacterial STD in the US?

C. trachomatis

335

What is the most common cause of urethritis and epididymitis in US men, and the most common cause of urethritis, cervicitis, and acute salpingitis in US women?

C. trachomatis

336

Does immunity to C. trachomatis confer long term protection against re-infection?

No

337

How can C. trachomatis be spread?  Can it be spread to a birthed infant?

Via abrasion of the skin; yes, via direct inoculation into the eyes and respiratory tract

338

What are genital syndromes caused by C. trachomatis?

Cervicitis, urethritis, epididymitis, salpingitis, infertility or ectopic pregnancy

339

Can Chlamydia cause infertility?

There is a strong relationship, and the pathogenesis is likely via chronic bilateral scarring of the fallopian tubes

340

What is the shape and gram staining of Neisseria gonorrhea?

Bean shaped gram-negative diplococci

341

Is N. gonorrhea more likely to spread male to female or the other way around?

Male to female but both are possible

342

Is N. gonorrhea more or less likely to be transmitted per episode of sex than HIV?

More likely

343

When is infection by N. gonorrhea most common?

Adolescents and young adults

344

Besides the genitourinary tract, where else can N. gonorrhea infections manifest?

Anorectal canal, pharynx, and around the liver

345

Does pharyngitis caused by N. gonorrhea usually present with symptoms?  If so, what are they?

No, it is usually asymptomatic

346

What causes pelvic inflammatory disease?

Usually, a bacterial super-infection secondary to N. gonorrhea infection

347

What is Fitz Hugh Curtis syndrome?

Perihepatitis caused by N. gonorrhea by direct extension of the organism from the fallopian tubes to the liver capsule

348

What kind of agar is used to culture N. gonorrhea?

Chocolate agar with antibiotics (Thayer Martin agar)

349

What is the typical first-line treatment for N. gonorrhea?

Ceftriaxone, 125mg intramuscular once

350

What is the second line agent of treatment for N. gonorrhea?

Azithromycin

351

What organism causes Chancroid?  Is it more common in the developing world or the US?

H. ducreyi; in the developing world