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MOD Final > Bacteria (Part II) > Flashcards

Bacteria (Part II) Flashcards

1
Q

What is the alpha-hemolytic encapsulated gram-positive bacteria?

A

streptococcus pneumoniae

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2
Q

how is streptococcus pneumoniae typically seen?

A

as diplococci or short chains

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3
Q

where does streptococcus pneumoniae colonize?

A

in the nasopharynx

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4
Q

what is the purpose of the capsule in streptococcus pneumoniae?

A

it provides a level of defense against direct phagocytosis by macrophages and inhibits complement activation

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5
Q

how can the swollen capsule of streptococcus pneumoniae be seen?

A

by the addition of the anti-capsular antibodies, which is the basis for the quelling test

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6
Q

what is streptococcus pneumoniae sensitive for?

A

optochin

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7
Q

what is the virulence factor for streptococcus pneumoniae?

A

IgA protease

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8
Q

what is so significant about streptococcus pneumoniae/ what does streptococcus pneumoniae cause?

A

it is the most common cause of community acquired PNA

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9
Q

how does PNA caused by streptococcus pneumoniae present?

A

lobar consolidative pattern where the entire lung lobe is involved with the pneumonic process with high fever, cough, SOB and chest pain

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10
Q

who is most at risk for streptococcus pneumoniae PNA?

A

elderly (older than 65)

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11
Q

what are the risk factors associated with getting streptococcus pneumoniae PNA?

A

COPD, smoking, previous influenza infection, immunocompromise, asplenia

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12
Q

What diseases can streptococcus pneumoniae cause?

A

pneumococcal PNA, meningitis, otitis media

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13
Q

what is the number 1 cause of meningitis in young children?

A

streptococcal pneumoniae

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14
Q

what is the classic triad of meningitis caused by streptococcus pneumoniae?

A

high fever, nuchal rigidity, and abnormal mental status change

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15
Q

what is the most common cause of meningitis in neonates?

A

streptococcus agalactiae, Escherichia coli, and listeria monocytogenes

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16
Q

what is the most common cause of meningitis in adolescence and very young adulthood?

A

Neisseria meningitides

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17
Q

What are the most common bacterial causes of otitis media?

A

streptococcus pneumoniae, Haemophilus influenzae, and moraxella catarrhalis

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18
Q

what is the only gram positive bacteria that commonly causes otitis media?

A

streptococcus pneumoniae

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19
Q

what are encapsulated bacteria cleared by?

A

the spleen

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20
Q

encapsulated bacteria can cause severe disease in asplenic patients. What are the top 3 encapsulated bacteria to remeber?

A

streptococcus pneumoniae, haemophilus influenza (type B), and Neisseria meningitis

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21
Q

what can cause asplenia or hyposplenism?

A

trauma, neoplasia or other disorders such as sickle cell anemia where entrapment of RBCs by the spleen leads to splenic infarction

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22
Q

where do the viridans group streptococci colonize?

A

gastrointestinal tract and the oral cavity

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23
Q

what diseases do the viridans group streptococci cause?

A

dental caries (cavities), subacute bacterial endocarditis, abscess in the brain and liver

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24
Q

What is the most well known member of the viridans group to cause dental caries?

A

streptococcus mutans

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25
Q

what is the most well known member of the viridans group to cause various abscesses (typically in the immunodeficient)?

A

streptococcus anginosus

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26
Q

what are the symptoms associated with the subacute endocarditis caused by viridans group streptococci?

A

insidious onset of low grade fevers, weakness, night sweats, loss of appetite, and weight loss

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27
Q

what is a typical clinical history of someone with a subacute endocarditis caused by viridans group streptococci?

A

endocarditis following an invasive dental procedure which allows the organisms to spread hematogenously to the heart valves

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28
Q

besides the viridans group streptococci, what is another cause of subacute bacterial endocarditis?

A

the HACEK organism (mouth colonizers)

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29
Q

what do enterococci appear morphologically similar to?

A

streptococci on gram stain (they appear as gram positive cocci in chains)

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30
Q

what are the enterococci part of (normal)?

A

normal bowel flora and nosocomial infections which are essentially hospital based opportunistic infections

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31
Q

what do enterococci grow on?

A

bile and 6.5% NaCl (salt)

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32
Q

what are the most important members of the normal bowel flora? (2)

A

Enterococci faecalis and enterococci facium

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33
Q

what diseases do enterococci cause?

A

wound infections, urinary tract infections, biliary tract infections, subacute endocarditis

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34
Q

what does the group D non-enterococci grow on?

A

bile but not 6.5% NaCl (salt)

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35
Q

what is the most important member of the group D non-enterococci group?

A

streptococcus bovis

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36
Q

what is streptococcus bovis strongly associated with?

A

colon cancer

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37
Q

what are the two major oxygen loving (aerobic) species in the spore-forming gram positive bacilli group?

A

Bacillus cereus and bacillus anthracis

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38
Q

what is bacillus cereus responsible for?

A

diarrheal illness

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39
Q

what is bacillus anthracis responsible for?

A

anthrax

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40
Q

what are 4 anaerobic clostridium species in the spore-forming gram positive bacilli group?

A

clostridium difficile, clostridium botulinum, clostridium tetani, and clostridium perfringens

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41
Q

what is a special characteristic of bacillus cereus?

A

the spores are extremely heat resistant- it can persist despite being exposed to cooking temperatures

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42
Q

what happens once bacillus cereus contaminates food?

A

the spores germinate within the food to create bacterial forms which then can elaborate enterotoxins

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43
Q

what is one of the enterotoxins created once the bacillus cereus spores germinate?

A

heat stabile toxin- it is not neutralized through simple reheating

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44
Q

what is the disease caused by heat stabile toxin?

A

emetic disease: nausea/vomiting, abdominal cramps within 1-3 hours of toxin ingestion

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45
Q

what is a classic example of a food contaminated with bacillus cereus?

A

reheated rice

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46
Q

besides the heat stabile toxin, bacillus cereus can also release what other toxin? and what does this toxin cause?

A

heat labile toxin; causes diarrheal disease: watery diarrhea, nausea, abdominal cramps

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47
Q

how is the diarrheal toxin released by bacillus cereus different from the emetic toxin?

A

the diarrheal toxin is heat labile and a had a longer incubation period (of at least 8 hours)

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48
Q

what are the spores of bacillus anthracis resistant to?

A

environmental changes such as drying, heating, and chemicals

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49
Q

where are spores of bacillus anthracis found?

A

on herbivore animals/products (hides) and in soil

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50
Q

what are the virulence factors associated with bacillus anthracis?

A

plasmid encoded: (pX01, pX02)

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51
Q

what is a person who handles herbivore animals/products skins contaminated with bacillus anthracis at risk for?

A

the development of cutaneous anthrax

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52
Q

how does cutaneous anthrax begin?

A

it starts as a localized disease, with a black ulcerated necrotic lesion termed “malignant pustule”

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53
Q

what happens if cutaneous anthrax is not treated?

A

more widespread infection can occur with systemic signs (painful lymphadenopathy and edema), which can lead to death

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54
Q

what are the other forms of anthrax? (not cutaneous anthrax)

A

inhalational anthrax, gastrointestinal anthrax, and injectional anthrax

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55
Q

what occurs with inhalational anthrax?

A

a spore is inhaled, and it remains latent in the lower airways where macrophages ingest and transport them to the mediastinal lymph nodes. There can be a prolonged latent period (> 2 months); symptoms like fever and myalgia occur first but within 3 days there is mediastinal hemorrhage followed by respiratory failure and sepsis

56
Q

what is a key finding of inhalational anthrax?

A

mediastinal widening due to the mediastinal hemorrhage (can be seen on chest x ray)

57
Q

what are all clostridium species?

A

gram positive, anaerobic spore forming rods

58
Q

what is clostridium difficile the causative organism of?

A

antibiotic associated colitis

59
Q

why does clostridium difficile infection usually follow a course of antibiotics?

A

antibiotics kill the normal gastrointestinal flora which makes it easier for C diff to cause infection because it no longer has to compete with the normal flora

60
Q

how is c. difficile infection caused?

A

bacterial spores through fecal oral contamination

61
Q

what are the virulence factors associated with c difficile?

A

Toxin A and Toxin B

62
Q

what are the effects of toxin A released from c. difficile?

A

increase in inflammation and fluid secretion (diarrhea)

63
Q

what are the effects of toxin B released from c difficile?

A

cytotoxic to colonic epithelial cells

64
Q

what is the disease associated with c difficile?

A

non-bloody diarrhea, abdominal pain, and fever

65
Q

what are the pathological key findings associated with c difficile?

A

pseudomembranous colitis- a colitis which grossly shows exudative yellowish colonic plaques

66
Q

how can c difficile be detected?

A

through nucleic acid testing or detection of its toxins in the stool

67
Q

what can clostridium botulinum spores contaminate?

A

food

68
Q

what happens when clostridium botulinum grows from the spores that are on food?

A

it elaborates a neurotoxin, which causes botulism

69
Q

what are the classic examples of food products that cause botulism?

A

poorly performed at-home canned food, smoked fish, and raw HONEY

70
Q

what is the effect of the neurotoxin that is released from C. botulinum?

A

it inhibits the release of acetylcholine at the neuromuscular junction blocking the cholinergic neuromuscular innervation of both striated and smooth muscle

71
Q

what happens when the neurotoxin that is released by C. botulinum is ingested by the adult?

A

bilateral cranial neuropathies and descending muscle weakness can occur which can ultimately lead to respiratory paralysis and death

72
Q

how does infantile botulism present?

A

with constipation which progresses in a couple of days to difficulty swallowing and muscle weakness; generalized hypotonia can occur giving rise to “floppy baby syndrome”

73
Q

how do infants get botulism?

A

consumption of spores from honey and infant powder

74
Q

where is clostridium tetani found?

A

in soil everywhere

75
Q

what is clostridium tetani associated with?

A

deep puncture wounds

76
Q

what is clostridium tetani notable for producing?

A

a potent neurotoxin which inactivates glycine and GABA causing sustained muscle contraction

77
Q

what is the result of the neurotoxin released by clostridium tetani?

A

severe muscle spasms, autonomic instability, risus saronicus, lockjaw, opisthotonos

78
Q

how does autonomic instability present?

A

sweating, tachycardia, labile blood pressure (both hyper and hypotension)

79
Q

what is opisthotonos?

A

arching of head, neck, and spine/body

80
Q

where are clostridium perfringens spores found? and what can they contaminate?

A

in soil–> they can contaminate deep wounds/ trauma

81
Q

what does clostridium perfringens cause?

A

gas gangrene (essentially starts as a cellulitis that can progress to myonecrosis which is necrosis of the muscle)

82
Q

what is one clue to the diagnosis of clostridium perfringens in less obvious cases?

A

on palpation, one can often reveal crackling as there are small pockets of gas trapped in the tissue (this is crepitus)

83
Q

what do the virulence factors released by clostridium perfringens cause?

A

hemolysis and hemorrhage

84
Q

historically, gas gangrene was seen in when?

A

in World War I and II

85
Q

if there is clostridial perfringes food contamination, what occurs?

A

diarrhea, abdominal cramps, necrotizing enteritis (super rare)

86
Q

what is corynebacterium diphtheriae notable for?

A

it shape- namely that of a pleomorphic club shaped rod

87
Q

what is corynebacterium diphtheriae cultured on for identification?

A

specialized media (Loeffler’s medium)

88
Q

what virulence factors does corynebacterium diphtheriae produce?

A

an AB exotoxin

89
Q

what are the nonspecific manifestations seen with corynebacterium disease?

A

fever, headache, malaise, cough, adenopathy

90
Q

what is the key finding of corynebacterium disease? aka the key effect of AB toxin

A

pharyngitis with pseudomembrane formation (yellow/gray inflammatory exudate–> DO NOT SCRAPE, will cause a systemic absorption of toxin)

91
Q

with systemic absorption, what does AB toxin affect?

A

the heart and nerves–> leads to myocarditis (dysrhythmias, AV conduction block) and neural involvement (cranial and peripheral nerve palsies)

92
Q

what is rhodococcus equi?

A

a gram positive, partially acid fast pleomorphic clubbed rod, facultative intracellular bacteria

93
Q

where is rhodococcus equi found?

A

in a variety of mammals, manure, soil

94
Q

what does rhodococcus equi cause?

A

pulmonary disease in the immunocompromised and it can cause abscess cavities with prominent air fluid levels on chest x-ray

95
Q

what might a chest x-ray look like of a person infected with rhodococcus equi?

A

upper lung nodules and cavities with air-fluid levels

96
Q

what is listeria monocytogenes?

A

a gram positive anaerobic intracellular facultative anaerobic rod; grows at cooler temperatures

97
Q

where is listeria monocytogenes found?

A

in contaminated dairy products (milk, soft cheeses), meat (deli and hot dogs), sprouts

98
Q

who is at risk for getting listeria monocytogenes?

A

pregnant women–> there is a high risk of infection of baby

99
Q

what does listeria monocytogenes cause in the healthy?

A

mild influenza-like illness often with an acute self-limited gastroenteritis termed Listeriosis

100
Q

what does listeria monocytogenes infection cause in the fetus and neonate? (2)

A

1) widespread granulomatous infantiseptica (often fatal results in stillbirth) 2) Neonatal meningitis with septicemia via fecal contamination (occurs later like 2-3 weeks after birth)

101
Q

Like group B strep, listeria monocytogenes can also cause what?

A

sepsis in the mother

102
Q

what effect does listeria monocytogenes have on older adults and the immunocompromised, including those that are taking immunosuppressive medicines like corticosteroids?

A

meningitis

103
Q

What are the three gram negative diplococci?

A

neisseria meningitis, neisseria gonorrhea, and moraxella cararrhalis

104
Q

how can the gram negative diplococci be grown?

A

on heat lysed blood agar termed “chocolate agar”

105
Q

what is the Thayer-Martin or VPN agar plate?

A

the vancomycin, polymyxin, and nystatin plate- it selects for neisseria growth only

106
Q

where does neisseria meningitis colonize?

A

in the nasopharynx

107
Q

What are the major virulence factors of N. meningitis?

A

a capsule, IgA protease, and pili; it also contains an endotoxin on its outer cell membrane- LPS

108
Q

what are the susceptible populations for neisseria meningitis infection?

A

neonates (1/2-2 years), military recruits, college students (dorms), and asplenia/hyposplenia patients

109
Q

what diseases can be caused by neisseria meningitis?

A

meningitis and meningococcemia

110
Q

what is meningococcemia?

A

meningitis+ septicemia

111
Q

what does meningococcemia cause?

A

waterhouse-friderichsen syndrome

112
Q

what is waterhouse-friderichsen syndrome?

A

bilateral adrenal hemorrhage with insufficiency, severe hypotension, disseminated intravascular thrombosis, death

113
Q

what is neisseria gonorrhoeae?

A

facultative anaerobic and facultative intracellular gram negative diplococci

114
Q

what is the second most common bacterial sexually transmitted disease? And what is it behind

A

neisseria gonorrhoeae; behind chlamydia

115
Q

what are the virulence factors of neisseria gonorrhoeae?

A

IgA1 protease, pili, opa proteins

116
Q

what is the purpose of the pili virulence factor?

A

it allows the organism to adhere to non-ciliated cells

117
Q

What diseases does neisseria gonorrhoeae cause in men?

A

urethritis and acute epididymitis

118
Q

what are the symptoms of urethritis in men?

A

discharge and dysuria

119
Q

what are the symptoms of acute epididymitis in men?

A

posterior testicular pain and swelling

120
Q

what diseases does neisseria gonorrhoeae cause in women?

A

urethritis, cervicitis, pelvic inflammatory disease and perihepatitis

121
Q

what are the symptoms of urethritis in women?

A

typically asymptomatic, if there are any symptoms it would be dysuria

122
Q

what are the symptoms of cervicitis?

A

typically asymptomatic, but if there are symptoms it will be itching and discharge

123
Q

what is pelvic inflammatory disease?

A

infection of the uterus, fallopian tubes, ovaries–> can cause sterility, can present with pelvic/abdominal pain

124
Q

in some women, neisseria gonorrhoeae affects the liver- how so?

A

perihepatitis (Fitz-Hugh-Curtis syndrome): inflammation of the liver capsule; presents as sharp right upper quadrant pleuritic pain

125
Q

how does neisseria gonorrhoeae affect both men and women?

A

disseminated gonococcal infection–> septic arthritis

126
Q

how does neisseria gonorrhoeae affect infants?

A

ophthalmia neonatorum–> neonatal conjunctivitis

127
Q

what is moraxella catarrhalis?

A

a gram negative aerobic diplococcus

128
Q

what is the most common disease caused by moraxella catarrhalis?

A

otitis media

129
Q

Besides otitis media, what is another disease that can be caused by moraxella catarrhalis, and who is susceptible to this disease?

A

can cause bronchopneumonia in elderly patients

130
Q

what are the gram negative enteric bacteria? (description)

A

a very diverse group of pathogenic bacteria; many enterics are bacteria that arise from the gastrointestinal tract to cause disease

131
Q

what is the broad breakdown of the enterics? (list 4)

A

the enterobacteriaceae, the pseudomonadaceae, the bacteriodaceae, the vibrionaceae

132
Q

what is the effect when a pathogenic organism involves the intestine, but does not invade the bowel wall?

A

it causes watery diarrhea

133
Q

what is the effect when bacteria invades the intestinal epithelium?

A

direct epithelial cell death can result–> causes bloody diarrhea

134
Q

what are 2 examples of organisms that cause watery diarrhea (lack of invasion)?

A

enterotoxigenic E. coli and Vibrio cholera

135
Q

what are 3 examples of organisms that can cause intestinal epithelium invasion/death leading to fever, bloody diarrhea, and abdominal cramps?

A

enterohemorrhagic and enteroinvasive E. coli and Shigella

136
Q

what happens when the bacteria invade the lymph nodes and get into the blood stream?

A

bloody diarrhea can occur as well as fever and abdominal pain; ultimately if bacteria enter the blood stream, bacteremia with sepsis can occur

137
Q

what are 3 examples of organisms that can cause invasion into the lymph nodes and blood stream?

A

salmonella typhi, yersinia enterocolitica, and campylobacter jejuni

MOD Final (11 decks)

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