Micro - Bacteriology (Part 1) Flashcards
(200 cards)
1
Q
A patient presents to your clinic with this painless lesion on his penis. What is the most likely diagnosis?
A
Syphilis
2
Q
What medication should be given for prophylaxis after a close contact is infected with the organism shown?
Image appears to show Neisseria meningitidis, a Gram-negative diplococcus often identified in cases of meningococcal infection.
A
Rifampin
3
Q
A 25-year-old woman presents with vaginal discharge that looks like this on microscopy. What is your diagnosis and treatment plan?
A
Gardnerella vaginalis infection; treatment with metronidazole
4
Q
What type of organisms stain purple/blue with Gram staining?
A
Gram-positive organisms
5
Q
Gram-positive organisms are commonly classified into which two shapes?
A
Cocci or rods (bacilli)
6
Q
Name four gram-positive rods.
A
Clostridium, Listeria, Bacillus, and Corynebacterium
7
Q
Name one gram-positive anaerobic rod.
A
Clostridium
8
Q
Staphylococcus and Streptococcus are differentiated by which enzyme?
A
Catalase; Staphylococcus is catalase positive, and Streptococcus is catalase negative
9
Q
Which gram-positive cocci are found in clusters?
A
Staphylococcus
10
Q
Which gram-positive cocci are found in chains?
A
Streptococcus
11
Q
What differentiates Staphylococcus aureus from and other staph species?
A
Other staph species are coagulase negative
12
Q
Name two coagulase-negative Staphylococcus species.
A
Staphylococcus saprophyticus and Staphylococcus epidermidis
13
Q
Which Staphylococcus species is novobiocin sensitive?
A
Staphylococcus epidermidis
14
Q
Which Staphylococcus species is novobiocin resistant?
A
Staphylococcus saprophyticus
15
Q
If agar shows clear hemolysis, which Streptococcus species could be present?
A
Streptococcus pyogenes or Streptococcus agalactiae
16
Q
What type of hemolysis do both group A and group B streptococci have in common?
A
β-Hemolysis
17
Q
Streptococcus pyogenes is a type of group _____ Streptococcus, whereas Streptococcus agalactiae is a type of group _____ Streptococcus.
A
A, B
18
Q
How are β-hemolytic streptococci differentiated from each other?
A
By their bacitracin sensitivity (Streptococcus pyogenes is sensitive, Streptococcus agalactiae is resistant)
19
Q
Name two streptococci that are γ-hemolytic.
A
Enterococcus and Streptococcus bovis
20
Q
True or False:
Enterococcus faecalis is a γ-hemolytic, gram-positive, catalase-negative cocci.
A
TRUE
21
Q
Which β-hemolytic streptococcal species is bacitracin resistant?
A
Group B Streptococcus (Streptococcus agalactiae)
22
Q
Which β-hemolytic streptococcal species is bacitracin sensitive?
A
Group A Streptococcus (Streptococcus pyogenes)
23
Q
Staphylococcus saprophyticus is novobiocin _____ (resistant, sensitive); staphylococcus epidermidis is novobiocin _____ (resistant, sensitive).
A
Resistant; sensitive (remember: On the staph retreat there was NO StRES; Novobiocin: Saprophyticus Resistant, Epidermidis Sensitive)
24
Q
Group A streptococci are bacitracin _____ (resistant, sensitive); group B streptococci are bacitracin _____ (resistant, sensitive).
A
Sensitive; resistant (remember: Bacitracin: group B are Resistant, whereas group A are Sensitive (B-BRAS)
25
*Streptococcus viridans* is optochin _____ (resistant, sensitive); *streptococcus pneumoniae* is optochin _____ (resistant, sensitive).
Resistant; sensitive (remember, **O**ptochin: **V**iridans **R**esistant and **P**neumonia **S**ensitive; **OVRPS**- overpass)
26
What bacterial enzyme degrades hydrogen peroxide?
Catalase
27
What antimicrobial product produced by polymorphonuclear lymphocytes is a substrate for myeloperoxidase?
Hydrogen peroxide
28
Which gram-positive cocci are catalase positive?
Staphylococci
29
What differentiates *Staphylococcus aureus* from *Staphylococcus epidermidis* and *Staphylococcus saprophyticus*?
Coagulase (*Staphylococcus aureus* is coagulase positive)
30
Why do people with chronic granulomatous disease (nicotinamide adenine dinucleotide phosphate oxidase deficiency) get recurrent infections by catalase-producing organisms?
Bacterial catalase easily degrades the little hydrogen peroxide produced, compromising the ability of neutrophils to kill bacteria
31
What is the function of Protein A, a *Staphylococcus aureus* virulence factor?
Binding to fragment crystallizable region-immunoglobulin G, to inhibit complement fixation and phagocytosis
32
Name five types of infections caused by *Staphylococcus aureus*.
Skin infections, organ abscesses, pneumonia, acute bacterial endocarditis, and osteomyelitis
33
*Staphylococcus aureus* can cause which toxin-mediated conditions?
Toxic shock syndrome (toxic shock syndrome toxin 1), scalded skin syndrome (exfoliative toxin), and rapid-onset food poisoning (enterotoxins)
34
Which organism produces toxic shock syndrome toxin 1?
*Staphylococcus aureus*
35
What is the pathophysiology of toxic shock syndrome?
Toxic shock syndrome toxin 1 acts as a superantigen and causes widespread release of cytokines from T cells
36
*Staphylococcus aureus* can cause rapid-onset food poisoning as a result of what product?
Preformed enterotoxins
37
Methicillin-resistant *Staphylococcus aureus* is resistant to methicillin because of its altered structure of what protein?
Penicillin-binding protein
38
What bacterium found in normal skin flora commonly contaminates blood cultures and infects prosthetic devices and catheters?
*Staphylococcus epidermis*
39
How does *Staphylococcus epidermis* infect prosthetic devices and intravenous catheters?
By producing adherent biofilms
40
What four common infections does *Streptococcus pneumoniae* cause?
Meningitis, Otitis media, Pneumonia, and Sinusitis (remember: MOPS are Most OPtochin Sensitive)
41
What is distinct about the pneumonia caused by pneumococcus?
"Rust"-colored sputum
42
*Streptococcus pneumoniae* sepsis occurs at a higher rate in what two patient populations?
Sickle cell anemia and asplenic patients
43
Name two ways *Streptococcus pneumoniae* evades the immune system.
Immunoglobulin A protease, encapsulation
44
What three pyogenic infections does *Streptococcus pyogenes* cause?
Pharyngitis, cellulitis, and impetigo
45
What two toxigenic diseases does *Streptococcus pyogenes* cause?
Scarlet fever and toxic shock syndrome
46
What two immunologic conditions does *Streptococcus pyogenes* cause?
Rheumatic fever and glomerulonephritis (remember: **PH**aryngitis gives you rheumatic "**PH**ever" and glomerulone**PH**itis)
47
*Streptococcus pyogenes* is associated with what three major classes of disease?
Infectious, immunogenic, and toxigenic
48
Human antibodies to *Streptococcus* M protein enhance host defenses but increase the risk for which complication of streptococcal infection?
Rheumatic heart disease
49
What blood test would detect a recent *Streptococcus pyogenes* infection?
An antistreptolysin O titer
50
Rheumatic fever is associated with what five symptoms?
**S**ubcutaneous nodules, **P**olyarthritis, **E**rythema marginatum, **C**horea, and **C**arditis (remember, there is no "**RHEUM**" for **SPECC**ulation)
51
# Fill in the blank.
*Streptococcus agalactiae* are bacitracin _____ (sensitive/resistant) and \_\_\_\_\_-hemolytic.
resistant, β
52
In what population does group B *Streptococcus* (*Streptococcus agalactiae*) cause pneumonia, meningitis, and sepsis?
Babies (remember: **B** for **B**abies)
53
What two infections do enterococci cause?
Urinary tract infection and subacute bacterial endocarditis
54
How can group D enterococci be differentiated from nonenterococcal group D streptococci by lab testing?
Enterococci can grow in 6.5% sodium chloride, other group D streptococci cannot
55
Lancefield grouping is based on differences in what components of the bacteria?
C carbohydrate on the bacterial cell wall
56
True or False? Penicillin G is effective treatment against enterococci.
False; enterococci are resistant to penicillin G
57
Enterococci resistant to which antibiotic are an important source of nosocomial infection?
Vancomycin
58
What two infections does *Streptococcus gallolyticus* (formerly Streptococcus bovis) cause in colon cancer patients?
Bacteremia and subacute endocarditis
59
A young patient presents with pseudomembranous pharyngitis; what medium could be used to culture the most likely etiologic agent?
*Corynebacterium diphtheriae* grows on tellurite agar (*coryne* = club shaped)
60
The symptoms of diphtheria are caused by what kind of toxin?
Exotoxin (encoded on the β-prophage)
61
How does diphtheria toxin inhibit protein synthesis?
By the adenosine diphosphate ribosylation of elongation factor 2
62
What disease is caused by *Corynebacterium diphtheriae*?
Diphtheria; characterized by pseudomembranous pharyngitis (grayish-white membrane) with lymphadenopathy
63
How is a laboratory diagnosis of diphtheria made based on microscopic appearance?
The presence of gram-positive rods with metachromatic granules (blue and red in color)
64
How can diphtheria be prevented?
Toxoid vaccine; usually administered in combination with tetanus vaccine
65
What type of bacteria form spores?
Gram-positive rods
66
What advantages do bacteria gain by taking the form of a spore?
They become highly resistant to destruction by heat and chemicals and require no metabolic activity in nutrient-poor settings
67
Why is it important to autoclave surgical equipment?
To kill bacterial spores
68
What five soil-dwelling, gram-positive rods are spore formers?
*Bacillus anthracis, Bacillus cereus, Clostridium perfringens, Clostridium botulinum*, and *Clostridium tetani*
69
Which bacteria are gram-positive, spore-forming, obligate anaerobic bacilli?
Clostridia species
70
Name four clostridia species that produce exotoxins.
*Clostridium tetani, Clostridium botulism, Clostridium perfringens* and *Clostridium difficile*
71
What kind of toxin produced by *Clostridium tetani* causes symptoms of tetanus?
An exotoxin called tetanospasmin
72
Describe the pathogenesis of the symptoms caused by *Clostridium tetani*?
*Clostridium tetani* toxins block glycine (an inhibitory neurotransmitter) release from Renshaw cells in the spinal cord, leading to spastic paralysis, lockjaw (trismus), and risus sardonicus (remember: **TET**anus is **TET**anic paralysis)
73
Which gram-positive bacilli are responsible for the flaccid paralysis caused by exposure to improperly canned foods?
*Clostridium botulinum* (remember: **BOT**ulinum is from bad **BOT**tles of food)
74
What are the characteristics of the toxin produced by *Clostridium botulinum*?
Preformed, heat-labile toxin
75
What is the predominant symptom of botulism?
Flaccid paralysis
76
How does the toxin produced by *Clostridium botulinum* cause flaccid paralysis?
It inhibits acetylcholine release
77
How does the pathogenesis of botulism differ between adults and babies?
Adults consume preformed toxin whereas babies consume spores in honey (floppy baby syndrome)
78
Which exotoxin-producing, gram-positive bacillus is responsible for gas gangrene?
*Clostridium perfringens* (remember: **PERF***ringens* **PERF**orates a gangrenous leg)
79
What is the effect of the toxin produced by *Clostridium perfringens*?
Toxin (lecithinase) causes myonecrosis, gas gangrene, and hemolysis
80
Which gram-positive bacillus is responsible for pseudomembranous colitis?
*Clostridium difficile* (remember: **DI***fficile* causes **DI**arrhea)
81
Pseudomembranous colitis often follows a course of which antibiotics?
Clindamycin, ampicillin, cephalosporins, or fluoroquinolones
82
What kind of toxin is produced by *Clostridium difficile*?
# Footnote
It produces **two** exotoxins:
* **Toxin A** (enterotoxin)
* **Toxin B** (cytotoxin)
## Footnote
Toxin A disrupts brush borders in the intestine, causing fluid secretion and diarrhea.
Toxin B depolymerizes the actin cytoskeleton, leading to cell death and pseudomembranous colitis.
83
What is the treatment of choice for pseudomembranous colitis caused by *Clostridium difficile*?
Oral vancomycin or fidaxomicin; IV metronidazole for severe cases
84
What gram-positive, spore-forming rod that produces a toxin causes a respiratory illness that is associated with black skin lesions and exposure to animal hides and fur?
*Bacillus anthracis*
85
*Bacillus anthracis* toxin causes what kind of skin lesion?
Black skin lesions (painless eschars, necrosis) surrounded by edematous ring
86
The skin changes of cutaneous anthrax are caused by which two toxins?
Lethal factor and edema factor cause a black eschar with surrounding edema at the site of inoculation
87
The inhalation of *Bacillus anthracis* spores leads to which symptoms?
Flu-like symptoms that rapidly progress to fever, mediastinitis, pulmonary hemorrhage, and shock
88
What are the two modes of anthrax inoculation?
Cutaneous and pulmonary
89
What is Woolsorters disease?
Pulmonary infection of *Bacillus anthracis* due to inhalation of spores from contaminated wool
90
How is the capsule produced by *Bacillus anthracis* unique?
It is the only bacterium to have a polypeptide capsule (contains D-glutamate)
91
What diseases does *Listeria monocytogenes* cause in pregnant women?
Amnionitis, septicemia, and spontaneous abortions
92
How does the disease caused by *Listeria monocytogenes* differ among adults, neonates, and immunocompromised individuals?
In healthy individuals it causes a mild gastroenteritis but can cause meningitis in neonates and immunocompromised patients
93
How is *Listeria monocytogenes* acquired?
By ingestion of unpasteurized milk, cheese, or deli meats or by vaginal transmission during birth
94
How does *Listeria monocytogenes* move from cell to cell?
Listeria is an intracellular organism that induces "actin rockets" to move into new cells
95
*Listeria monocytogenes* has what identifying characteristic on microscopy?
Tumbling motility
96
What distinguishes *Listeria monocytogenes* from all other gram-positive bacteria?
It is the only gram-positive bacterium to have an endotoxin
97
Which two bacteria are gram-positive rods that form long-branching filaments that resemble fungi?
*Actinomyces israelii* and *Nocardia asteroides*
98
Which is an anaerobe: *Actinomyces israelii* or *Nocardia asteroides*?
*Actinomyces israelii*
99
Which is a weakly acid-fast aerobe in soil: *Actinomyces israelii* or *Nocardia asteroides*?
*Nocardia asteroides*
100
Describe the lesions caused by *Actinomyces israelii*.
Oral/facial abscesses that may drain through sinus tracts
101
True or False? *Actinomyces* are part of the normal oral flora.
TRUE
102
What type of disease does *Nocardia asteroides* cause in immunocompromised individuals?
Pulmonary infection
103
How are infections with *Actinomyces israelii* and *Nocardia asteroides* treated?
**SNAP**: **S**ulfa for **N***ocardia*; for **A***ctinomyces*, use **P**enicillin
104
What is a characteristic finding in the draining sinuses caused by *Actinomyces israelii* infection?
Yellow "sulfur granules"
105
What two mycobacteria species are often resistant to multiple drugs?
*Mycobacterium tuberculosis* and *Mycobacterium avium-intracellulare*
106
What symptoms are caused by *Mycobacterium kansasii*?
Pulmonary tuberculosis-like symptoms
107
Infection with *Mycobacterium avium-intracellulare* is symptomatic in which patient group?
Patients with AIDS
108
What are the symptoms of tuberculosis?
Fever, night sweats, weight loss, and hemoptysis
109
Describe the leonine facies of leprosy caused by *Mycobacterium leprae*.
Loss of eyebrows, nasal collapse, and lumpy earlobe
110
What is another name for leprosy?
Hansens disease
111
The organism that causes leprosy has what animal reservoir in the United States?
Armadillos
112
Because *Mycobacterium leprae* likes cool temperatures, it tends to infect what areas of the body?
The skin and the superficial nerves
113
What is the treatment of choice for leprosy?
Long-term oral dapsone
114
What toxicity is associated with long-term oral dapsone treatment?
Hemolysis and methemoglobinemia
115
What are two alternative treatment options for leprosy?
Rifampin and the combination of clofazimine and dapsone
116
What are the two forms of Hansens disease?
Lepromatous and tuberculoid
117
Which of the two forms of leprosy indicates failed cell-mediated immunity and has a worse prognosis?
**L**epromatous = **L**ethal
118
Which of the two forms of leprosy is self-limited?
Tuberculoid
119
True or False? *Mycobacterium leprae* can be grown in vitro.
FALSE
120
How can the skin lesions of lepromatous and tuberculoid leprosy be differentiated?
Lepromatous skin lesions present diffusely over the skin and are communicable (failed cell-mediated immunity) whereas tuberculoid skin lesions are limited to a few hypoesthetic nodules
121
Gram-negative organisms can be classified into what three shapes?
Cocci, coccoid rods, and rods
122
Name four organisms that are gram-negative, coccoid rods.
*Haemophilus influenzae, Bordetella pertussis, Pasteurella*, and *Brucella*
123
What is a common source of *Pasteurella* infections?
Animal bites
124
Name two gram-negative cocci.
*Neisseria meningitidis* and *Neisseria gonorrhoeae*
125
How are the two gram-negative cocci differentiated from each other?
By maltose fermentation (*Neisseria meningitidis* is a maltose fermenter; *Neisseria gonorrhoeae* is not)
126
Gram-negative rods are differentiated by the fermentation of what substance?
Lactose
127
Name three fast lactose-fermenting, gram-negative rods.
*Klebsiella, Escherichia coli,* and *Enterobacter*
128
Name two slow lactose-fermenting, gram-negative rods.
*Citrobacter* and *Serratia*
129
Among nonlactose fermenters, the presence of what substance can be used to differentiate *Pseudomonas* from *Shigella, Salmonella*, and *Proteus*?
Oxidase (*Pseudomonas* is oxidase positive, *Shigella, Salmonella*, and *Proteus* are oxidase negative)
130
What type of bacteria grows pink colonies on MacConkeys agar?
Lactose-fermenting enteric bacteria
131
Name five bacteria that grow pink colonies on MacConkeys agar.
**C***itrobacter*, **K***lebsiella*, **E***scherichia coli*, **E***nterobacter*, and **S***erratia* (remember: test with Mac**C**on**KEES**)
132
True or False? Gram-negative organisms are resistant to penicillin and all of its derivatives.
False; some gram-negative organisms are susceptible to penicillin derivatives such as ampicillin
133
What part of gram-negative organisms inhibits the entry of penicillin G and vancomycin?
The outer membrane
134
*Neisseria meningitides* _____ (does/does not) have a polysaccharide capsule; *Neisseria gonorrhea* _____ (does/does not) have a polysaccharide capsule.
Does; does not
135
*Neisseria meningitides* _____ (does/does not) have a vaccine; *Neisseria gonorrhea* _____ (does/does not) have a vaccine.
Does; does not
136
# Fill in the blanks.
*Neisseria meningitides* \_\_\_\_\_\_\_ (does/does not) ferment maltose; *Neisseria gonorrhea* \_\_\_\_\_\_\_\_ (does/does not) ferment lactose.
does; does not
137
What five types of infection can *Neisseria gonorrhea* cause?
Gonorrhea, pelvic inflammatory disease, septic arthritis, Fitz-Hugh-Curtis syndrome, and neonatal conjunctivitis
138
What three clinical syndromes can *Neisseria meningitides* cause?
Septicemia, meningitis, and Waterhouse-Friderichsen syndrome
139
How is *Neisseria gonorrhoeae* transmitted?
Sexually transmitted
140
How is *Neisseria meningitidis* transmitted?
Respiratory and oral secretions
141
Why can a vaccine to *Neisseria gonorrhea* not be created?
Rapid antigenic variation
142
Name four diseases that can be caused by *Haemophilus influenzae*.
**E**piglottitis, **M**eningitis, **O**titis media. and **P**neumonia (remember: *Ha**EMOP**hilus)*
143
What is the method of transmission of *Haemophilus influenzae*?
Aerosol
144
Which type of *Haemophilus influenzae* causes the most invasive disease?
Capsular type B
145
*Escherichia coli, Salmonella, Shigella, Klebsiella, Enterobacter, Serratia*, and *Proteus* belong to which bacterial family?
Enterobacteriaceae
146
All species in the enterobacteriaceae have what type of antigen?
Somatic (O) antigen, which is the endotoxin polysaccharide
147
All enterobacteriaceae species ferment _____ and are oxidase \_\_\_\_\_.
Glucose; negative
148
What is the somatic (O) antigen?
The polysaccharide of endotoxin
149
What does the capsular (K) antigen tell you about the enterobacteriaceae species?
Certain K antigens are correlated with more virulent species
150
Motile enterobacteriaceae species have what type of antigen?
Flagellar (H) antigen
151
Aside from diarrhea/dysentery, what diseases does *Escherichia coli* commonly cause?
Cystitis, pyelonephritis, pneumonia, neonatal meningitis, and septic shock
152
What three types of *Escherichia coli* do not invade the intestinal mucosa?
Enterohemorrhagic, enterotoxigenic, enteropathogenic; only enteroinvasive *Escherichia coli* invades the mucosa
153
Which *Escherichia coli* species produces shiga-like toxin?
Enteroinvasive and enterohemorrhagic *Escherichia coli*
154
What differentiates the disease caused by enteroinvasive *Escherichia coli* and enterohemorrhagic *Escherichia coli*?
Both cause dysentery, but with enteroinvasive, both the toxin and the microbe cause necrosis and inflammation; with enterohemorrhagic, only the toxin does
155
Which toxins mediate the diarrhea caused by enterotoxigenic *Escherichia coli*?
Labile toxin/stable toxin
156
What disease is caused by enterotoxigenic *Escherichia coli*?
Travelers diarrhea
157
How does enteropathogenic *Escherichia coli* cause diarrhea?
It adheres to the apical surface, flattens villi, decreasing absorption (this is NOT toxin mediated)
158
What population tends to get diarrhea following enteropathogenic *Escherichia coli* infection?
Children
159
What potentially fatal systemic complication can be caused by enterohemorrhagic *Escherichia coli* infection?
Hemolytic uremic syndrome
160
A seven-year-old child has a burger at a barbeque and subsequently develops diarrhea. He then ceases urinating, becomes lethargic, and is found to have low red blood cell and platelet counts. What is your diagnosis?
Hemolytic uremic syndrome secondary to infection with enterohemorrhagic *Escherichia coli*
161
What is the pathophysiology of hemolytic uremic syndrome?
Endothelial swelling and narrowing leads to mechanical hemolysis (anemia) and reduced renal blood flow (acute renal failure), with damaged endothelium consuming platelets (thrombocytopenia)
162
What bacteria classically causes "red currant jelly" sputum in a patient with pneumonia?
*Klebsiella*
163
An alcoholic man is admitted to the hospital with fever, dyspnea and is coughing up gelatinous red sputum. Chest x-ray is consistent with an abscess. What infection do you suspect?
*Klebsiella* (remember the "**4 As**": **A**bscess, **A**lcoholic, **A**spiration, and di**A**betics)
164
*Klebsiella* is a cause of what other nosocomial infection in addition to pneumonia?
Urinary tract infection
165
What do *Salmonella* and *Shigella* have in common?
They are both nonlactose-fermenting bacteria that invade the intestinal mucosa causing bloody diarrhea
166
Which of the following is motile and can disseminate hematogenously: *Salmonella* or *Shigella*?
*Salmonella*
167
How does *Shigella* propel itself within the cell?
By actin polymerization
168
Which antibiotics should be used to treat salmonellosis?
Salmonellosis should not be treated with antibiotics; doing so can prolong symptoms
169
Which leukocyte response is seen in salmonellosis?
Monocyte response
170
Which is more virulent: *Salmonella* or *Shigella*?
*Shigella* (101 *Shigella* organisms vs 105 *Salmonella* organisms)
171
Which has an animal reservoir: *Salmonella* or *Shigella*?
*Salmonella* (except *Salmonella typhi*, which is only found in humans); *Salmonella* is often acquired from reptiles and poultry
172
What are the modes of transmission of *Shigella*?
The "**4 Fs**": **F**ood, **F**ingers, **F**eces, and **F**lies
173
A woman presents to the clinic with fever, diarrhea, headache, and rose spots on her abdomen. What is the likely diagnosis?
The woman has typhoid fever caused by *Salmonella typhi*
174
Chronic carriers of *Salmonella* harbor the bacteria where in their bodies?
The gallbladder
175
What mode of propulsion do *Salmonella* use to disseminate?
Flagella
176
What are the usual modes of transmission of *Yersinia enterocolitica*?
Pet feces (eg, puppies) and contaminated milk or pork
177
*Yersinia enterocolitica* outbreaks are common in what setting?
Day-care centers
178
*Yersinia enterocolitica* infections can mimic what other diseases, particularly in teenagers?
Crohns disease or appendicitis
179
*Heliobacter pylori* causes what two pathologies in the gastrointestinal tract?
Duodenal ulcers and gastritis
180
*Heliobacter pylori* is a urease _____ (positive/negative), gram _____ (positive/negative) _____ (rod/cocci).
Urease-positive, gram-negative rod
181
What enzyme in *Helicobacter pylori* helps to create an alkaline environment?
Urease
182
*Heliobacter pylori* is a risk factor for what two cancers?
Gastric adenocarcinoma and lymphoma
183
A patient with a chronic ulcer is found to have a positive urease breath test. How would you treat the patient?
Triple therapy: (1) Bismuth, metronidazole, and either tetracycline or amoxicillin; or (2) (more costly) metronidazole, omeprazole, and clarithromycin
184
What are the three spirochete species that most commonly affect humans?
**B**orrelia (**B**ig size), **L**eptospira, and **T**reponema (remember: **BLT**)
185
What is the only spirochete that can be visualized by light microscopy with aniline dyes (ie, Wrights or Giemsa staining)?
**B**orrelia (remember: **B**ig size)
186
Which spirochete species is visualized by dark-field microscopy?
*Treponema*, which causes syphilis
187
A farmer in the tropics with contaminated water sources presents with fever, headache, abdominal pain, photophobia, and conjunctivitis. What infection do you suspect?
*Leptospira*
188
Leptospirosis is most prevalent in which geographical locations?
The tropics
189
What is Weils disease?
Severe leptospirosis, which presents with severe jaundice, azotemia, fever, hemorrhage, and anemia
190
What is another name for Weils disease?
Icterohemorrhagic leptospirosis
191
Where is *Leptospira interrogans* commonly found in the environment?
In water contaminated with animal urine
192
What is the cause of azotemia and jaundice in patients with Weils disease?
Renal and liver failure
193
The organism that causes Lyme disease is transmitted by what vector?
The *Ixodes* tick
194
What bacteria causes Lyme disease?
*Borrelia burgdorferi*
195
The classic symptom of Lyme disease, erythema chronicum migrans, has what appearance?
An expanding "bulls eye" red rash with central clearing
196
What organs are affected in patients with Lyme disease?
The skin, the joints, the central nervous system, and the heart
197
Which mammals are required for the life cycle of the *Ixodes* tick?
Deer and mice
198
What are the treatments of choice for Lyme disease?
Doxycycline and ceftriaxone
199
In what region of the United States is Lyme disease common?
The northeastern United States
200
What are the three stages of Lyme disease and their associated symptoms?
Stage 1: erythema chronicum migrans and flu-like symptoms;
stage 2: neurologic and cardiac manifestations;
stage 3: autoimmune migratory polyarthritis
