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MOD II Exam II > Bacteria > Flashcards

Bacteria Flashcards

1
Q

5 Morphologic characteristics of Staphylococcus aureus

A 
Gram-positive cocci
Catalase+
Coagulase+
Beta-hemolytic
Mannitol fermenter (turns salt agar yellow)
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2
Q

Main virulence factor associated with Staph aureus — component of cell wall which binds Fc region of Abs and prevents complement activation thus preventing opsonization and phagocytosis

A

Protein A

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3
Q

What area of the body does Staph aureus tend to colonize

A

Nares

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4
Q

8-9 Clinical manifestations of Staph aureus

A

Post-viral bacterial pneumonia (patchy infiltrate on CXR)

Septic arthritis (MCC)

Large erythematous abscesses

Rapid onset bacterial endocarditis (IV drug use, often tricuspid valve)

Osteomyelitis in adults (MCC)

Scalded skin syndrome, TSS, food poisoning (meats, mayo, salad, cream-filled pastries), MRSA d/t altered cell wall

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5
Q

3 morphologic features of Staphylococcus epidermidis and saprophyticus

A

Gram+
Catalase+
Urease+

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6
Q

What morphologic feature differentiates staphylococcus aureus from Staph epidermidis and saprophyticus?

A

Staph aureus is coagulase+

Epidermidis and saprophyticus are coag-

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7
Q

What organism is a part of normal skin flora and tends to infect hardware, orthopedic joints, heart implants, catheters, etc.?

What virulence factor contributes to its ability to do this?

A

Staphylococcus epidermidis

Ability to form biofilms to stick to metal and plastic surfaces

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8
Q

What organism is associated with contamination of blood cultures

A

Staph epidermidis

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9
Q

What is the major clinical manifestation of staphylococcus saprophyticus?

A

UTI’s in sexually active females (2nd most common cause to E.coli)

“Honeymoon cystitis”

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10
Q

Morphologic features of streptococcus pyogenes (group A strep)

A

Gram+ cocci in chains
Microaerophilic
Hyaluronic acid capsule
Beta-hemolytic

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11
Q

5 Virulence factors associated with S. pyogenes

A 
M-protein (anti-phagocytic, humoral response - Abs to heart)
Strep Toxin
Streptolysin O
Streptokinase
DNA-ase
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12
Q

Clinical manifestations of strep pyogenes infection (note which ones are toxin-mediated vs. M-protein mediated)

A

Pyogenic infections: Impetigo, strep throat, erysipelas, cellulitis

Toxin-mediated: Scarlet fever, TSLS, Necrotizing fasciitis

M protein-mediated: rheumatic fever = arthritis, endocarditis (mitral valve), nodules on extensor surfaces, erythema marginatum, sydenham’s chorea [JONES]

Post-streptococcal glomerulonephritis: facial edema, hematuria, HTN

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13
Q

How would you test for a group A strep infection?

A

ASO antibody titer

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14
Q

Symptoms of Scarlet fever

A

Strawberry tongue
Pharyngitis
Widespread rash that spares the face

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15
Q

Which superantigens mediate TSLS vs. Necrotizing fasciitis in strep pyogenes infections?

A

TSLS = SpeA, SpeC

Nec Fasc = SpeB

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16
Q

Post-streptococcal glomerulonephritis tends to occur after what type of strep pyogenes infection(s)?

A

Either pharyngitis OR superficial infection like impetigo

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17
Q

Rheumatic fever tends to occur after what type of strep pyogenes infection(s)?

A

Pharyngitis only (NOT impetigo!)

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18
Q

What organism tends to cause serious infections in newborns, thus pregnant mothers should be swabbed at ~35 weeks?

A

Streptococcus agalactiae (group B strep)

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19
Q

Morphologic features of strep agalactiae

A 
Gram+ cocci in chains
Facultative anaerobe
Beta-hemolytic
Polysaccharide capsule
CAMP test + (increasing zone of hemolysis)
Hippurate test +
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20
Q

Clinical manifestations of streptococcus agalactiae

A

Neonatal meningitis (no nuchal rigidity!)
Strep throat
Pneumonia

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21
Q

Morphologic features of streptococcus pneumoniae

A 
Gram + diplococci
Polysaccharide capsule
Alpha-hemolytic
Facultative anaerobe
Optochin-sensitive
Bile-soluble
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22
Q

Characteristic feature of otitis media caused by streptococcus pneumoniae

A

Bullous meringitis

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23
Q

Major virulence factors of strep pneumoniae

A

Polysaccharide capsule

IgA protease

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24
Q

Diagnosis of strep pneumoniae involves the ____ reaction, which turns blue in the presence of strep pneumo

A

Quelling

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25
Q

Clinical manifestations of streptococcus pneumoniae

A

MCC of MOPS:

Meningitis
Otitis media
Pneumonia - often lower lobes, PMN-rich rust-colored sputum
Sinusitis

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26
Q

Morphologic features of streptococcus viridans

A 
Gram+ cocci in chains
Facultative anaerobe
Alpha-hemolytic
Optochin-resistant
Bile-resistant
No capsule!
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27
Q

Major virulence factor associated with streptococcus viridans

A

Extracellular dextrans —> adheres to platelets

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28
Q

Clinical manifestations of streptococcus viridans

A

Dental caries

Subacute bacterial endocarditis (only affects previously damaged heart valve — usually mitral valve)

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29
Q

Morphologic features of S. bovis

A

Gram+ cocci in chains
Facultative anaerobe
Usually gamma-hemolytic
Grows on bile

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30
Q

Clinical manifestations of S. bovis

A

Same as enterococcus: subacute bacterial endocarditis, UTI, biliary tract infection

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31
Q

S. bovis has a strong affilitation with what type of neoplasm?

A

Colorectal neoplasms

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32
Q

Morphologic features of Enterococcus faecalis and faecium

A

G+ cocci in chains
Facultative anaerobe
Usually gamma-hemolytic
Grows on bile and 6.5% NaCl

[Hugely abx resistant (VRE), nosocomial infections]

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33
Q

Morphologic features of Bacillus anthracis

A

Gram+ rods in chains (unique!)
Protein capsule (poly-D-glutamate)
Obligate aerobe
Spore-former

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34
Q

Differentiate the 2 toxins associated with bacillus anthracis

A

Lethal factor — protease exotoxin that causes tissue necrosis via IL-1B and TNF

Edema factor — acts on adenylate cyclase to increase cAMP —> edema (resists phagocytosis)

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35
Q

Complication of GI anthrax

A

Necrosis of intestines

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36
Q

Characteristic lesion associated with B.anthracis

A

Black eschar with surrounding erythema

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37
Q

Describe pulmonary anthrax

A

Caused by spore inhalation (wool sorter’s disease)

Nonspecific symptoms at first, characteristic widened mediastinum on CXR, progresses to pulmonary hemorrhage

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38
Q

Characteristics of bacillus cereus

A

Aerobic
Spore-forming
Motile
No capsule!

Food poisoning from reheating fried rice — vomiting and diarrhea (heat labile vs. heat stable toxin)

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39
Q

Oxygen-status of all clostridium species

A

Obligate anaerobes

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40
Q

Morphologic features of Clostridium tetanin

A

Gram+
Flagellated (H-Ag)
Spore-forming

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41
Q

Describe tetanus toxin associated with Clostridium tetani

A

Tetanospasmin — released from spores, goes from peripheral motor nerves to spinal cord. Acts as a protease on SNARE, inhibiting GABA and Glycine —> muscle spasm (spastic paralysis)

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42
Q

Characteristic features of C.tetani infection

A

Spastic paralysis leading to rigidity
Rhesus sardonicus (lock jaw)
Opisthotonus (exaggerated arching of back)

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43
Q

Morphologic fefatures of clostridium botulinum

A

Gram+
Flagellated (H-Ag)
Spore-former

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44
Q

Clinical features of C.botulinum infection

A

Adults: DESCENDING flaccid paralysis (only affects PNS), starts with diplopia, ptosis as initial symptoms

Infants: floppy baby syndrome

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45
Q

Pathogenesis of C.botulinum infection in adults vs. infants

A

Adults: ingestion of preformed toxin (once it has germinated in improperly canned food), toxin then inhibits ACh nerves — toxin is a protease that attacks SNARE protein

Infants: ingest honey that contains SPORES

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46
Q

Morphologic features of Clostridium difficile

A

Gram+
Spore former
Motile (H-Ag)

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47
Q

Describe exotoxin associated with C.difficile

A

Exotoxin A = binds brush border — watery diarrhea

Exotoxin B = depolymerizes actin — enterocyte destruction and necrosis —> pseudomembranous colitis

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48
Q

How is C.difficile definitively diagnosed?

A

Look for toxin via PCR assay of stool

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49
Q

Morphologic features of Clostridium perfringens

A

Gram+
Spore former
Non-motile!

(found in dirt and soil - associated with combat wounds and motorcycle accidents)

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50
Q

Diseases associated with Clostridium perfringens and their pathogenesis

A

Gas gangrene (myonecrosis) — crackling sound on palpation d/t alpha-toxin lecithinase that attacks PM leading to RBC hemolysis

Food poisoning — late-onset watery diarrhea — ingest spores which then germinate in gut

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51
Q

Morphologic features of Corynebacterium diphtheriae

A 
Gram+ club-shaped
Metachromatic granules (V or Y formation)
Bacteriophage-derived toxin
Facultative anaerobe
Catalase+
Aerosol transmission
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52
Q

Describe the corynebacterium diphtheriae toxin

A

Acts by ribosylation — inhibits EF-2 to inhibit protein synthesis —> gray pseudomembrane formation over throat and tonsils - can cause airway obstruction and “Bull’s neck” LAD

Other effects: myocarditis, arrhythmia, heart block, local paralysis d/t myelin damage

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53
Q

Diagnosis of C.diptheria requires plating on what media?

How would you differentiate toxic vs. nontoxic strains?

A

Tellurite and Loeffler’s agar/media

Differentiate strains based on Elek’s test

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54
Q

Morphologic characteristics of Listeria monocytogenes

A 
Gram+ bacilli
Beta-hemolytic
Motile (H-Ag) — “tumbling” motility
Catalase+
Facultative intracellular
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55
Q

Risks for contracting Listeria monocytogenes

A

Can survive in cold environments — contaminates refrigerated items like milk and soft cheeses

Pregnant women at risk - can give baby meningitis (meningitis also occurs in elderly with this)

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56
Q

What allows L.monocytogenes to escape the phagolysosome?

A

Listeriolysin O

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57
Q

What conditions are associated with Moxarella catarrhalis infection?

A

Otitis media in pediatric patients (<3 y/o)

COPD exacerbations and URI/PNA in elderly

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58
Q

Morphologic features of Neisseria

A

Gram-negative diploccoci

Oxidase+

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59
Q

Since Neisseria cannot be grown on plain blood agar, what are the culture requirements for plating Neisseria?

A 
Chocolate agar (heated blood agar)
VPN agar (Thayer Martin)
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60
Q

Virulence factors associated with Neisseria

A

Pilli — allow attachment to mucosa, antigenic variation

IgA protease — facilitates survival on mucosal surfaces

Opa proteins

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61
Q

Which species of Neisseria is encapsulated (polysaccharide)? How is it transmitted?

A

Neisseria meningiditis

Spread by respiratory droplets — first colonizes nasopharynx

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62
Q

Neisseria meningiditis ferments ____ and ______. Most infections are caused by type _____ because it is not included in the vaccine. _____ patients are at increased risk for this disease

A

Glucose; maltose; B; asplenic and sickle cell

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63
Q

Neisseria invades hematogenously leading to a massive immune response generated by what?

A

LOS proteins in envelope — causes inflammatory response, leaky capillaries, petechial rash indicative of thrombocytopenia (can lead to DIC) —> eventual hypovolemic shock

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64
Q

What is Waterhouse-Fridrichson syndrome?

A

Occurs with Neisseria meningiditis — characterized by hemorrhage of adrenals

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65
Q

Morphologic features of Neisseria gonorrheae

A 
Gram-negative cocci
Facultative intracellular (likes to infect PMNs)

Note that it is NOT encapsulated, and only ferments glucose (unlike N.meningiditis which is encapsulated and ferments glucose+maltose)

66
Q

Clinical manifestations in N.gonorrheae in males vs. females

A

Males: urethritis, white purulent discharge —> prostatitis, orchitis

Females: white purulent discharge, PID —> scarring, infertility, ectopic pregnancy, Fitz-Hugh Curtis syndrome (violin string adhesions on liver) = PID spread to peritoneum

Both may exhibit polyarthritis (knees, often asymmetric)

Note that it can also be passed to baby during delivery causing early onset conjunctivitis

67
Q

Fast vs. slow lactose fermenters

A

Fast: Klebsiella, E.coli, Enterobacter

Slow: Citrobacter, Serratia

68
Q

What bacteria are urease+?

A

Klebsiella pneumoniae
Proteus mirabilis
Helicobacter pylori

69
Q

Which bacteria exhibit the following diarrheal manifestation:

Lack of cell wall invasion — entertoxin release leads to watery diarrhea

A

ETEC

Vibrio cholerae

70
Q

Which bacteria exhibit the following diarrheal manifestation:

Invasion of intestinal epithelium — adhere, invade, toxin release —> system response results in WBC and RBC in stool, fever

A

EIEC
Shigella
S.enteriditis

71
Q

Which bacteria exhibit the following diarrheal manifestation:

Invasion of lymph nodes and bloodstream — WBC, RBC, abdominal pain; systemic response can lead to sepsis and bacteremia

A

S.typhi
Y.enterocolitica
C.jejuni

72
Q

Describe characteristics of Enterobacter cloacae

A

Part of normal flora - cause pneumonia, UTI (multi-drug resistant nosocomial infections)

Ferments lactose (forms pink cultures on MacConkey agar)

Motile

73
Q

Describe characteristics of Serratia marcescens infection

A

Often infects wounds, causes pneumonia, UTIs (multi-drug resistant nosocomial infections)

Motile; red pigment on culture

74
Q

Klebsiella pneumoniae is an enteric with the potential to cause pneumonia, UTI, etc. and like other enterics, ferments lactose. What are the other morphologic features of Klebsiella?

A

Polysaccharide capsule (O-Ag)
Immotile
Urease+

75
Q

Characteristic findings for someone with a Klebsiella pneumonia

A

Bulging fissure on CXR
Currant jelly-thick sputum
Cavitary lesions — may originally suspect Tb

76
Q

Morphologic features of Salmonella typhi

A 
Gram-negative bacilli
Motile (H-Ag)
H2S positive —> black colonies on Hektoen agar
Encapsulated (VI Ag)
Acid labile
Siderophore
Intracellular
77
Q

Where would you find S.typhi in chronic carriers?

A

Gallbladder

78
Q

Clinical features of Salmonella typhi infection

A

Rose-colored macules on abdomen
Osteomyelitis in pts with sickle cell (MCC)
Pea soup-diarrhea

79
Q

Morphologic features of Salmonella enteriditis

A 
Gram-negative bacilli
Motile
H2S+ —> black colonies on Hektoen agar
Encapsulated
Acid-labile
Facultative intracellular (within macrophages)
Type III secretion system
80
Q

Clinical features of Salmonella enteriditis

A

Acquired by eating undercooked chicken

Causes inflammatory diarrhea

81
Q

How would you differentiate Shigella from Salmonella infection in terms of plating?

A

Green colonies on Hektoen agar (Salmonella colonies are black)

82
Q

Morphologic features of Shigella

A 
Gram-negative bacilli
Immotile
Acid stable
Facultative intracellular within M cells
Type III secretion system
Shiga toxin
83
Q

MOA of shiga toxin

A

Inhibits 60s portion of ribosomes — inhibits translation

84
Q

Clinical manifestations of shigella infection

A

Causes bloody diarrhea (inflammatory containing RBCs and WBCs)

Shiga toxin may cause HUS in young patients —> glomerular damage, thrombocytopenia

85
Q

Morphologic characteristics of E.coli

A 
Gram-negative bacilli
Lactose fermenter (pink MacConkey agar)
Siderophore
Indole+
Green on EMB agar
Encapsulated (K-Ag)
Catalase+
86
Q

Which type of E.coli infection is often derived from undercooked meat and causes bloody diarrhea, and is also the only E.coli that does not ferment sorbitol?

A

EHEC

87
Q

Describe the toxin associated with EHEC

What strain is associated with outbreaks?

A

Shiga-like toxin — causes HUS d/t capillary damage in glomerulus —> platelet aggregation and decrease in platelet count, RBC hemolysis

O157:H7 Ag associated with outbreaks

88
Q

Describe the illness and toxin associated with ETEC

A

Traveler’s diarrhea from drinking contaminated water - causes watery diarrhea

Heat labile —> increased cAMP (similar to cholera toxin)
Heat stable —> increased cGMP

89
Q

Characteristics of yersinia enterocolitica

A

Found in puppy feces and milk products — commonly affects toddlers leading to bloody diarrhea, fever, leukocytosis

Resistant to cold temps
Bipolar (safety pin) staining
Encapsulated

90
Q

Which bacterial infection can mimic an appendicitis?

A

Yersinia enterocolitica

91
Q

Characteristics of Yersinia pestis

A

Reservoir = rodents, vector = fleas
Bubonic plague —> buboes (LAD)
Endotoxin—>necrosis of tissues
Yops secreted via type III secretion system

92
Q

Characteristics of Campylobacter jejuni

A

Thermophilic
Curved gram-negative rod
Oxidase+

Main reservoir = intestinal tract of animals (poultry) - fecal-oral transmission

93
Q

Clinical manifestations of Campylobacter jejuni

A

Bloody diarrhea, bacteremia d/t invasiveness, reactive arthritis (Reiter’s)

Post-complication = Guillain Barre —> ascending paralysis

94
Q

Characteristics of Bacteroides fragilis

A

Gram-negative bacillus
Anaerobic
Normal flora of GI tract
NO lipid A!

95
Q

Clinical manifestations of Bacteroides fragilis

A

Secondary infection following abdominal trauma and/or localized abscesses

May complicate abortion, tubo-ovarian abscess, IUD

96
Q

Clinical manifestations of Bacteroides melaninogenicus and fusobacterium

A

Melaninogenicus - can cause a necrotizing anaerobic pneumonia, following GI aspiration; may also exhibit pneumonic and periodontal manifestations

Fusobacterium may have similar disease manifestations and rarely the etiology of otitis media

97
Q

Characteristics of vibrio cholerae, parahemolyticus, and vulnificus

A

Gram-negative bacillus
Endemic to developing countries (SE Asia)
“Comma” shaped, grows on alkaline medium (acid labile)
Oxidase+

98
Q

Transmission and clinical manifestations of vibrio cholerae

A

Fecal-oral transmission via contaminated food/water - causes profuse watery diarrhea

99
Q

Main virulence factor and pathogenesis of vibrio cholerae

A

Fimbriae attach to intestinal wall and toxin is released —> increased cAMP —> secretion of water into lumen

[other virulence factors: mucinase, motile via H-Ag]

100
Q

What 2 bacteria are at high risk of transmission via contaminated seafood, typically oysters?

A

Vibrio parahemolyticus and vulnificus

101
Q

Morphologic characteristics of Helicobacter pylori

A

Curved Gram-negative bacilli
Motile
Oxidase+
Urease+ (important for reducing acidity of environment)

102
Q

Clinical manifestations of H.pylori

A

Duodenal ulcers

Increased risk of gastric adenocarcinoma, MALTomas

103
Q

Morphologic characteristics of Pseudomonas aeruginosa

A 
Gram-negative rod
Oxidase+
Catalase+
Encapsulated
Produces pyocyanin and pyoverdin —> blue/green pigment
Fruity grape odor
Obligate aerobe
104
Q

What distinguishes psuedomonas aeruginosa from other enterics?

A

It is an obligate aerobe while most others are facultative anaerobes

105
Q

Clinical manifestations of pseudomonas aeruginosa

A

1 cause of gram-negative nosocomial pneumonia

Pulmonary infections in CF patients
Osteomyelitis in IV drug users and diabetics
Complication of burns
Nosocomial UTIs
Ecthyma gangrenosum (black necrotic skin lesions)
Otitis externa

106
Q

What other toxin is the pseudomonas toxin similar to?

A

Diphtheria toxin — because it also inactivates EF-2 by ribosylation

107
Q

Characteristics of proteus mirabilis

A 
Gram-negative rod
Urease+
H2S+
Facultative anaerobe
Swarming motility, may have fishy odor
Staghorn calculi

May cause UTI

108
Q

Proteus mirabilis cross-reacts with what other bacterial species?

A

Rickettsia

109
Q

Characteristics of Bordetella pertussis

A

Gram-negative rod

Filamentous hemagglutinin pilus attaches to respiratory epithelium and releases toxins

110
Q

Pathogenesis of Bordetella pertussis toxins

A

Pertussis toxin:
Ribosylates Gi (disabling it) —> increased cAMP
Lymphocytosis (increased WBC)

AC toxin:
Increases cAMP [edema factor]

Tracheal toxin:
Damages respiratory epithelium

111
Q

Clinical findings associated with bordetella pertussis

A

Paroxysmal phase: 1-2 wks of nonspecific findings including conjunctival injection, lacrimation, followed by characteristic cough

Convalescent phase: cough can last months

112
Q

Characteristics of Haemophilus influenzae

A 
Gram-negative rod
Grown on chocolate agar with factor V (NAD+) and X
Pilli
IgA protease
Aerosol transmission
113
Q

Clinical manifestations of encapsulated Haemophilus influenzae

A

Epiglottitis: inspiratory stridor, drooling, “cherry-red epiglottis”

Otitis media

Meningitis (type B capsule only - most virulent)

Sepsis, etc. in asplenic or sickle cell patients

114
Q

Clinical manifestations of nonencapsulated Haemophilus influenzae

A

Lack of invasiveness, so just causes COPD exacerbations and otitis media

115
Q

Clinical manifestations of Haemophilus ducreyi

A

Chancroid (STI) — rapid, unilateral inguinal LAD

116
Q

Morphologic characteristics of Legionella pneumophilia

A

Gram-negative rod, but needs silver stain to be visualized

Oxidase+
Charcoal yeast with cysteine+iron for plating
Facultative intracellular

Found in respiratory tract; amoebas

117
Q

How are infections with Legionella pneumophilia diagnosed?

A

Rapid urine Ag test

118
Q

Clinical manifestations of the 2 types of infections with Legionella pneumophilia

A

Legionnaire’s disease — more common in smokers; atypical pneumonia with unilobar patchy infiltrate, hyponatremia, headache, confusion, diarrhea, fever

Pontiac fever — fever, malaise, cough - more self-limited

119
Q

Morphologic characteristics of Bartonella henselae infection

A

Gram-negative rod (zoonotic)

Warthin starry silver stain

120
Q

What diseases are caused by Bartonella henselae and what are their clinical features?

A

Cat-scratch disease: fever, regional LNs (axillary), occurs in immunocompetent

Bacillary angiomatosis: also transmitted by cat scratches, occurs in immunocompromised (HIV) — fever, chills, HA, raised red vesicular lesions (similar to Kaposi sarc)

121
Q

Characteristics of Brucella bordis

A

Gram-negative rod (zoonotic)
Found in farm animals or in milk/cheese
Facultative intracellular in macrophages

122
Q

Clinical features of Brucella bordis infection

A

Since it colonizes macrophages, it causes HSM and LAD

Undulent fever, chills, anorexia

123
Q

Characteristics of Francisella tularensis

A

Gram-negative rod
Encapsulated
Facultative intracellular in macrophages

Vectors: ticks and deerfly
Reservoirs: rabbits, squirrels

POTENTIAL BIOTERRORISM AGENT — one of the most infectious pathogenic agents

124
Q

Clinical features of infection with Francisella tularensis

A

Ulceroglandular tularemia — Painful ulcer with black base (center with caseating necrosis), fever, LAD, systemic symptoms

Pneumonia tularemia — high mortality rate; via inhalation. Severe atypical pneumonia

125
Q

Morphologic features of Pastuerella multicoda

A 
Gram-negative rod
Catalase+
Oxidase+
Sheep’s blood agar
Encapsulated
Bipolar staining (safety pin) -like yersinia

Found in respiratory tract of small mammals - cat and dog bites

126
Q

Clinical features of pasteruella multicoda infection

A

Cellulitis within 24 hours of bite —> osteomyelitis

127
Q

What differentiates pasteurella multicoda from other zoonotics?

A

It is not facultative intracellular

128
Q

Morphologic features of Mycobacterium tuberculosis

A 
Acid-fast (mycolic acid in cell wall)
Carbol fuscin stain
Slow growing on Loenstein-Jensen medium
Obligate aerobe
Facultative intracellular (macrophages)
129
Q

Virulence factors of Mycobacterium tuberculosis

A

Cell wall has glycolipids —> cord factor protects from destruction by forming caseating granulomas (tubercles)

Sulfatides prevent phagolysosome fusion

130
Q

Clinical features of Mycobacterium tuberculosis infection

A

Transmission via respiratory droplets

Healed primary infection affects lungs (usually lower or middle lobe) and forms Ghon complex affecting hilar LNs. 3 outcomes:

Healed latent infection —> fibrosis and +PPD (type IV HSR)

Systemic infection (miliary Tb) —> fulminant multiorgan failure

Reactivation Tb —> d/t immunosuppression —> TNF activation; affects upper lobes leading to hemoptysis, night sweats, Pots disease, meningitis, tuberculoma

131
Q

Characteristics of Mycobacterium avium complex

A

Acquired from environment

Key player for immunocompromised - AIDS pts with CD4<50, elderly smokers

Causes nodularities and bronchiectasis in middle aged non-smokers

Lymphadenitis in kids

132
Q

Characteristics of Ureaplasma urealyticum infection

A

Pleomorphic, no cell wall, requires cholesterol, urease

Non-gonococcal urethritis: burning dysuria, yellow mucoid urethral discharge

133
Q

Characteristics of Mycobacterium leprae

A

Acid-fast (carbol fuscion stain)
Mycolic acids in cell wall
Thrives in cool temps

Main reservoir: armadillos

134
Q

Clinical presentation(s) with Mycobacterium leprae infection

A

Tuberculoid: Th1 cell-mediated — macrophage-contained; well-demarcated skin plaque

Lepromatous: Th2 cells promote humoral response — not contained in macrophages; high chance of human-human transmission, glove/stocking neuropathy, lesions on extensor surfaces, profound facial deformity (leonine facies)

135
Q

Characteristics of Borrelia burgdorferi

A

Spirochete
Wright stain and Giemsa stain

Ixodes tick is vector; reservoirs are mice, obligatory hosts are deer

136
Q

Clinical features of Borrelia burgdorferi infection

A
  1. Erythema migrans (bullseye rash), fever, chills
  2. Heart block (myocarditis), bilateral Bell’s palsy
  3. Migratory polyarthritis, encephalopathy
137
Q

Characteristics of Leptospira interrogans

A

Spirochete
Aerobic
Endemic in tropical areas
Associated with water sports in water contaminated with animal urine

138
Q

Clinical features of Leptospira interrogans infection

A

Phase 1 (CSF) - HIGH fever, HA, malaise, myalgias, conjunctival suffusion (no pus)

Phase 2 (immune) - IgM Ab meningismus; renal dysfunction and jaundice from liver damage (infectious jaundice), multiple organ hemorrhage, AMS

139
Q

Characteristics of Treponema pallidum

A

Spirochete
Dark field microscopy required, or use VDRL or RPR followed by confirmatory FTA-Ab test

Causes syphilis

140
Q

Clinical manifestations of adult syphilis

A

Primary: painless genital chancre - heals in 3-6 weeks

Secondary: systemic: maculopapular rash on palms/soles within weeks to months, condyloma lata on mucous membranes

Tertiary: formation of gummas = soft growths with necrotic firm center, aortitis (tree-barking appearance), destruction of vasa vasorum of aorta —> aneurysm, tabes dorsalis (damage to posterior columns), Argyll Robertson pupils — react to accommodation but not to light

141
Q

Clinical features of congenital syphilis

A

Anterior bowing of tibia (saber shins), saddle nose, Hutchinson teeth and Mulberry molars, deafness, hepatomegaly, rhinitis, rash

142
Q

What is the Jarisch Herxheimer rxn?

A

When you first treat syphilis with penicillin, symptoms may worsen prior to improving — fever, chills, HA

143
Q

Characteristics and life cycle of Chlamydia trachomatis

A

Gram-negative obligate intracellular
No peptidoglycan or muramic acid
Giemsa stain to visualize
Dx with NAAT test

Life cycle:
Elementary body: infectious particle, inhibits phagocytosis

Reticulate body (initial body): forms from EB via binary fission

144
Q

Clinical features of 3 groups of Chlamydia trachomatis

A

A-C: blindness

D-K: watery discharge, cervicitis, epididymitis, PID, neonatal transfer—> conjunctivitis, pneumonia

L1-L3: lymphogranuloma venaerum - painless genital ulcer, tender LAD in inguinal region

145
Q

Complications of C.trachomatis infection

A

Reactive arthritis (Reiter’s syndrome) “Can’t see, can’t pee, can’t climb a tree” — conjunctivitis, urethritis, arthritis

Fitz Hugh Curtis syndrome (perihepatitis)

146
Q

Clinical features of Chlamydia pneumoniae and psittaci

A

pneumoniae: atypical pneumonia - more common in elderly
psittaci: causes pneumonia; transmission by bird droppings

147
Q

Characteristics and clinical features of coxiella burnetti

A

Gram negative
Obligate intracellular

Causes Q fever — fever, pneumonia (cough), HA, hepatitis

Contained in spores in animal poop, Aerosol transmission; does not cause rash

148
Q

Clinical features of Gardnerella vaginalis

A

Gram negative bacillus that causes bacterial vaginosis (bacterial overgrowth of normal flora)

Vaginal discharge, grayish white with pH 5-6.5, dysuria, pruritis

Dx via KOH whiff test or Clue cells (epithelial cells coated in bacteria)

149
Q

Characteristics of mycoplasma pneumoniae

A

No cell wall - won’t gram-stain
Grows on Eatons agar

Only bacteria with cholesterol in cell membrane

150
Q

Clinical features of Mycoplasma pneumoniae infection

A

Causes “walking pneumonia” with patchy infiltrate

Increased incidence in young adults and military recruits - close quarters

Dx via cold agluttinins (clumped RBCs in cold temps) - IgM, may also see bullous meringitis on PE

Associated with erythema multiforme and Steven Johnson syndrome

151
Q

Rickettsia morphology

A

Gram-negative but doesn’t stain well (pleomorphic)
Obligate intracellular
Unable to produce NAD or CoA

Dx with Weil Felix agluttination test

152
Q

Clinical features of early undetermined Rickettsia infection

A

Prodromal headache and fever, vasculitis/rash

153
Q

Clinical features of Rickettsia prowazekii infection

A

Rash starting on trunk and spreading to extremities, SPARES hands/feet; myalgia, arthralgia, PNA, encephalitis, dizziness, confusion, coma

Affects military recruits and POWs

Spread by louse poop that gets into scratches

Causes epidemic typhus (OX-19) — widespread rapid outbreak

154
Q

Clinical features of Rickettsia rickettsii infection

A

Rocky Mtn Spotted Fever, OX-19, OX-2

Transmission via dermacentor ticks

Rash takes 2-14 days to develop, extends from extremities —> centrally; headache, fever, myalgias

155
Q

Clinical features of Rickettsia akari infection

A

Rickettsial pox: mild, self-limiting fever; blister at bite site then vesicular rash and headache — Weil Felix NEGATIVE

156
Q

What condition is very similar to Rocky Mtn Spotted Fever but is NOT associated with a rash?

A

Erlichiosis

157
Q

Morphology of actinomyces israelii

A

Gram+ filamentous branching rod

Obligate anaerobe

158
Q

Clinical manifestations of actinomyces israelii infection

A

Part of normal flora of oral cavity

Jaw trauma (such as with dental work) causes infection. Starts as a lump and proceeds to form abscess. Can then infect sinus tracts and drainage of yellow sulfur granule material

159
Q

Morphology of Nocardia asteroides

A 
Gram+ filamentous branching rod
Weakly acid-fast d/t mycolic acids
Obligate aerobe
Catalase+
Urease+

Found in soil but does NOT form spores

160
Q

Why is it significant to note if organisms are catalase+?

A

People with chronic granulomatous disease (CGD) are at increased risk of infection with catalase+ organisms

161
Q

Clinical manifestations of Nocardia asteroides

A

Primarily affects immunocompromised —> HIV pts, transplant pts, pts on glucocorticoids

Affects men > women

3 main sites of infection:

  • Pulmonary: PNA with lung abscesses (cavitary lesions)
  • CNS: brain abscesses
  • Cutaneous: pyogenic, indurated lesions (at risk when dirt gets in wounds)

MOD II Exam II (7 decks)

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