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USMLE1 - Microbiology > 2. Bacteria > Flashcards

2. Bacteria Flashcards

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1
Q

Gram (+) | Rods | ?

A

Clostridium (anaerobe) Corynebacterium Listeria Bacillus

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2
Q

Gram (+) | Cocci | Catalase (+), in clusters (Staphylococcus) | Coagulase (+) | ?

A

Staphylococcus aureus

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3
Q

Gram (+) | Cocci | Catalase (+), in clusters (Staphylococcus) | Coagulase (-) | ?

A

Novobiocin sensitive: Staphylococcus epidermidis Nobobiocin resistant: Staphylococcus saprophyticus

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4
Q

Gram (+) | Cocci | Catalase (-), in chains (Streptococcus) | partial hemolysis (green - alpha hemolysis) | ?

A

(+) Quellung (has capsule), Optochin sensitive, Bile soluble: Streptococcus pneumoniae (-) Quellung (no capsule), Optochin resistant, not bile soluble: Streptococcus viridans

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5
Q

Gram (+) | Cocci | Catalase (-), in chains (Streptococcus) | Complete hemolysis (clear, beta-hemolysis) | ?

A

Bacitracin sensitive: Group A Strep (GAS) aka Streptoccus pyogenes Bacitracin resistant: Group B strep aka Streptococcus agalactiae

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6
Q

Gram (+) | Cocci | Catalase (-), in chains (Streptococcus) | No hemolysis (gamma hemolysis) | ?

A

Enterococcus (E. faecalis) Peptostreptococcus (anaerobe)

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7
Q

Identifying Staphylococci w/ Novobiocin (once you know it’s a G(+)/catalase(+) coccus in clusters)

A

NO vobiocin - S aprophyticus is R esistant; E pidermidis is S ensitive On the office’s staph retreat, there was NO S tRES

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8
Q

Identifying Streptococci (once you know it’s a G(+)/catalase(-) coccus in chains)

A

O ptochin: V iridans is R esistant P neumoniae is S ensitive (OVRPS = overpass) B acitracin: group B strep are R esistant group A strep are S ensitive (B-BRAS )

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9
Q

alpha-hemolytic bacteria

A

Form a green ring around colonies on blood agar. Include: 1.) Streptococcus pneumoniae (catalase (-) and optochin sensitive) 2.) viridans streptococci (catalase (-), optochin resistant)

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10
Q

Beta-hemolytic bacteria

A

Form a clear area of hemolysis on blood agar. Include: 1.) Staphylococcus aureus (catalase and coagulase positive) 2.) Streptococcus pyogenes - GAS (catalase negative and bacitracin sensitive) 3.) Streptococcus agalactiae - GBS (catalase negative and bacitracin resistant) 4.) Listeria monocytogenes (tumbling motility, meningitis in newborns, unpasteurized milk)

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11
Q

Catalase

A

Catalase degrades H2O2, an antimicrobial product of PMNs. H2O2 is a substrate for myeloperoxidase.

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12
Q

Catalase/Coagulase in G(+) cocci

A

Staphylococci make catalase, whereas Streptococci do not S. aureus makes coagulase, whereas S. epidermidis and S. saprophyticus do not. (Staph make catalase b/c they have more staff. Bad staph (aureus, b/c epidermidis is skin flora) make coagulase and toxins.)

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13
Q

Protein A (virulence factor)

A

Virulence factor of Staphylococcus aureus Binds Fc-IgG, inhibiting complement fixation and phagocytosis

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14
Q

TSST (@ molecular level)

A

In Staph aureus A superAg that binds MHCII and the TCR, resulting in polyclonal T-cell activation

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15
Q

Dzs caused by Staphylococcus aureus

A

1.) Inflammatory Dz - skin infxns, organ abcesses, pneumonia 2.) Toxin-mediated dz - Toxic shock syndrome (TSST-1), scalded skin syndrome (exfoliative toxin), rapid-onset food poisoning (pre-formed enterotoxins) 3.) MRSA (methicillin-resistant S. aureus) infxn: important cause of serious nosocomial and community-acquired infxns. Resistant to beta-lactams due to altered penicillin-binding proteins. 4.) Misc. - acute bacterial endocarditis, osteomyelitis

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16
Q

Staphylococcus epidermidis

A

Infects prosthetic devices and catheters. Component of normal skin flora. Contaminates blood cultures.

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17
Q

Streptococcus pneumoniae (the pneumococcus)

A

Encapsulated. Has IgA protease. Most common cause of: Meningitis Otitis media (in children) Pneumonia Sinusitis (S. pneumoniae MOPS are M ost OP tochin S ensitive) Associated w/ rusty sputum, sepsis in sickle cell anemia and splenectomy.

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18
Q

Viridans group Streptococci

A

Alpha-hemolytic. Normal flora of the oropharynx. Cause dental caries (S. mutans) and subacute bacterial endocarditis (S. sanguis). Resistant to optochin, differentiating them from S. pneumoniae, which is alpha-hemolytic but optochin sensitive. (Viridans group strep live in the mouth b/c they are not afraid of-the-chin <–op-to-chin resistant)

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19
Q

Diseases caused by Streptococcus pyogenes (GAS)

A

1.) Pyogenic - pharyngitis, cellulitis, impetigo 2.) Toxigenic - Scarlet fever, toxic shock syndrome 3.) Immunologic - rheumatic fever, acute glomerulonephritis PH aryngitis gives you rheumatic PH ever and glomerulonePH ritis No rheum for SPECCulation: Subcutaneous nodules, Polyarthritis Erythema marginatum Chorea Carditis

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20
Q

Ab’s and Streptococcus pyogenes (GAS)

A

Ab’s to M protein enhance host defenses againt GAS but can give rise to rheumatic fever. ASO titer detects recent GAS infxn.

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21
Q

Streptococcus agalactiae (GBS)

A

Bacitracin resistant Beta-hemolytic Causes: Pneumonia meningitis Sepsis (mainly in babies) B is for Babies!

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22
Q

Enterococci

A

include Enterococus faecalis and E. faecium) Penicillin G resistant. Cause UTI and subacute endocarditis. Enterococci are hardier than nonenterococcal group D, thus can grow in 6.5% NaCl. Variable hemolysis.

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23
Q

Lancefield group D

A

Includes enterococci and nonenterococcal group D streptococci. Lancefield grouping is based on differences in the C carbohydrate on the bacterial cell wall.

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24
Q

VRE

A

Vancomycin-resistant Enterococci: an important cause of nosocomial infxn.

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25
Q

Streptococcus bovis

A

Highly associated w/ colon cancer. One of the group D streptococci.

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26
Q

Diphtheria

A

Caused by Corynebacterium diphtheriae via an exotoxin encoded by beta-prophage. Potent exotoxin inhibits protein synthesis via ADP ribosylation of EF-2. Sx include: pseudomembranous pharyngitis (grayish-white membrane) w/ lymphadenopathy. Lab Dx based on G(+) rods w/ metachromatic granules. Corynebacterium diphtheriae grows on tellurite agar. ABCDEFG ADP ribosylation Beta-prophage Corynebacterium Diphtheriae Elongation Factor 2 Granules

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27
Q

Bacterial spores

A

Certain G(+) rods form spores when nutrients are limited (@ the end of stationary phase) Spores are highly resistant to destruction by heat and chemicals. Have dipiclonic acid in their core. Have no metabolic activity. Must autoclave to kill spores.

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28
Q

Important spore-forming bacteria

A

G (+) spores found in soil: Bacillus anthracis Clostridium perfringens C. tetani Other spore formers: B. cerus C. botulinum

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29
Q

Clostridia (generally)

A

G(+) Spore-forming Obligate anaerobic Bacilli

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30
Q

Clostridium tetani

A

produces the exotoxin that causes tetanus TETanus is TETanic paralysis (blocks glycine release [an inhibitory NT]) from Renshaw cells in spinal cord

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31
Q

Clostridium botulinum

A

produces preformed, heat-labile toxin that inhibits ACh release at the NMJ, causing botulism (flaccid paralysis). In adults, dz is caused by ingestion of preformed toxin. In babies, ingestion of bacterial spores in honey causes dz (floppy baby syndrome). BOTulinum is from bad BOTtles of food and honey.

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32
Q

Clostridium perfringens

A

Produces alpha-toxin (lecithinase) that can cause myonecrosis (gas gangrene) and hemolysis PERFringens PERForates a gangrenous leg

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33
Q

Clostridium dificile

A

Produces a cytotoxin, an exotoxin that kills enterocytes, causing pseudomembranous colitis. Often 2’ to ABX use, especially clindamycin or ampicillin. DI fficile causes DI arrhea Tx: metronidazole

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34
Q

Anthrax

A

Caused by Bacillus anthracis: Gram (+), spore-forming rod that produces anthrax toxin. Only bacterium w/ a protein capsule (contains D-glutamate)

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35
Q

Anthrax infxn via contact

A

Malignant pustules (painless ulcer) Can progress to bacteremia and death Black skin lesions - vesicular papules covered by black eschar *[I think these only occur via contact route of infxn]

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36
Q

Anthrax via inhalation of spores

A

Flulike Sx that rapidly progress to fever, pulmonary hemorrhage, mediastinitis, and shock

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37
Q

Woolsorter’s dz

A

Anthrax caused by inhalation of spores from contaminated wool

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38
Q

Listeria monocytogenes route of transmission

A

Acquired by ingestion of unpasteurized milk/cheese and deli meats, or by vaginal transmission during birth.

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39
Q

Listeria monocytogenes motility

A

Form actin rockets by which they move from cell to cell. Characteristic tumbling motility.

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40
Q

Listeria monocytogenes Diseases

A

Can cause: amnionitis septicemia spontaneous abortion granulomatosis infantiseptica neonatal meningitis meningitis in the immunocompromised mild gastroenteritis (healthy individuals) *Note: is the only G(+) organism w/ endotoxin*

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41
Q

Actinomyces and Nocardia

A

Both are G(+) rods forming long branching filaments, resembling fungi SNAP: S ulfa for N ocardia, A ctinomyces use P CN

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42
Q

Actinomyces israelii

A

G(+) anaerobe Causes oral/facial abscesses that may drain thru sinus tracts in skin. Forms yellow sulfur granules in sinus tracts. Normal oral flora.

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43
Q

Nocardia asteroides

A

G(+) and also weakly acid-fast aerobe found in soil. Causes pulmonary infxn in immunocompromised pts.

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44
Q

Primary TB

A

Mycobacterium infects nonimmune host (usu. child). 1’ TB causes hilar nodes and Ghon focus (usu. in lower lobes) -> together = Ghon Complex Several outcomes: Heals by fibrosis Progressive lung dz Severe bacteremia Preallergic lymphatic or hematogenous dissemination

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45
Q

Primary TB (Heals by fibrosis)

A

Immunity and hypersensitivity | Tuberculin (+)

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46
Q

Primary TB | Progressive Lung dz

A

(Seen in HIV, malnutrition) | Death (rare)

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47
Q

Primary TB (severe bacteremia)

A

Miliary TB | Death

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48
Q

Primary TB Preallergic lymphatic or hematogenous dissemination

A

Dormant tubercle bacilli in several organs | Reactivation in adult life | Extrapulmonary TB or Reactivation of TB in lungs

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49
Q

Extrapulmonary TB

A

CNS (parenchymal tuberculoma or meningitis) Vertebral body (Pott’s dz) Lymphadenitis Renal GI

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50
Q

Secondary TB

A

Due to re-infxn of partially immune hypersensitized host (usu. adult) or reactivation of dormant TB in the lungs Causes Fibrocaseous cavitary lesion (usu. in upper lobes)

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51
Q

PPD test and TB

A

PPD (+) w/ current infxn, past exposure, or BCG vaccinated PPD (-) if no infxn or anergic (steroids, malnutrition, immunocompromise, sarcoidosis)

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52
Q

Ghon complex

A

TB granulomas (Ghon focus) w/ lobar and perihilar lymph node involvement. Reflects primary infxn or exposure.

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53
Q

Mycobacterium tuberculosis

A

Causes TB (Sx: fever, night sweats, weight loss, and hemoptysis) Often resistant to multiple drugs

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54
Q

Mycobacterium kansasii

A

pulmonary TB-like Sx

55
Q

Mycobacterium avium-intracellulare

A

Often resistant to multiple drugs Causes disseminated dz in AIDS

56
Q

Leprosy (Hansen’s dz)

A

Caused by Mycobacterium leprae, an acid-fast bacillus that likes cool temperatures (thus infects skin and superficial nerves), and cannot be grown in vitro. See common Sx below:

57
Q

Reservoir for leprosy in the USA

A

armadillos

58
Q

Tx for Leprosy

A

long-term oral dapsone Toxicity is hemolysis and methemoglobinemia Alternative Tx’s: Rifampin Combination of clofazimine and dapsone

59
Q

2 Forms of Hansen’s dz

A

Lepromatous: and Tuberculoid Lepromatous is worse (failed cell-mediated immunity); tuberculoid is self-limited LEpromatous is LEthal

60
Q

Classifying G(-) Cocci

A

Maltose fermenter: Neisseria meningitidis Maltose non-fermenter: Neisseria gonorrhoeae

61
Q

G(-) Coccoid rods

A

Haemophilus influenzae Pasteurella - (animal bites) Brucella - (brucellosis) Bordetella pertusis

62
Q

G(-) Rods | Lactose fermenters | ?

A

Fast fermenters: Klebsiella E. coli Enterobacter Slow fermenters : Citrobacter Serratia (others)

63
Q

G(-) Rods | Lactose non-fermenters | ?

A

Oxidase (-): Shigella Salmonella Proteus Oxidase (+): Pseudomonas

64
Q

Lactose-fermenting enteric bacteria

A

Grow pink colonies on MacConkey’s agar. Examples: C itrobacter, K lebsiella, E . coli, E nterobacter, S erratia (Lactose is KEE, so test w/ MacC onKEE’S agar

65
Q

PCN and Gram(-) bugs

A

G(-) bugs are resistant to benzylpenicillin G but may be susceptible to PCN derivatives such as ampicillin. The G(-) outer membrane inhibits entry of PCN-G and Vancomycin

66
Q

Neisseria (generally)

A

Both are: Gram(-) cocci Ferment glucose and produce IgA proteases.

67
Q

Neisseria gonorrheae (Gonococci)

A

No polysaccharide capsule No maltose fermentation (Gonococci ferment Glucose) No vaccine Sexually transmitted Causes gonorrhea, septic arthritis, neonatal conjunctivitis, PID

68
Q

Neisseria meningitidis (Meningococci)

A

Polysaccharide capsule Maltose fermentation (MeninGococci ferments Maltose and Glucose) Vaccine available Transmitted by respiratory and oral secretions Causes meningococcemia and meningitis, Waterhouse-Friderichsen syndrome

69
Q

Haemophilus influenzae Causes…? Produces what? Mode of transmission?

A

HaEMOP hilus causes: Epiglottitis, Meningitis, Otitis media, and Pneumonia. (Most invasive dz caused by capsular type B) Does NOT cause flu (influenza virus does) Produces IgA Protease Aerosol transmission

70
Q

Tx for Haemophilus influenzae

A

Ceftriaxone. Rifampin prophylaxis in close contacts.

71
Q

Culturing H. influenzae

A

Chocalate agar w/ factors V (NAD) and X (hematin) When a child has ‘flu’*, mom goes to the five (V ) and dime (X ) store to buy some chocolate [*remember that H. influenzae does not cause flu]

72
Q

Haemophilus influenzae vaccine

A

Contains type B capsular polysaccharide conjugated to diphtheria toxoid or other protein to improve immune system recognition of polysaccharide and promote class switching. Given btw 2 and 18 months of age.

73
Q

Legionella pneumophila

A

Gram (-) rod Gram stains poorly –> silver stain Grow on charcoal yeast extract culture w/ iron and cysteine. Think of a French legionnaire (soldier) with his silver helmet, sitting around a campfire (charcoal ) w/ his iron dagger – he is no sissy (cysteine )

74
Q

Transmission of Legionella pneumophilia

A

Aerosol transmission from environmental water souce habitat. no person-to-person transmission.

75
Q

Dz’s caused by Legionella pneumophila Tx?

A

Legionnaires’ dz (severe pneumonia) Pontiac fever (mild influenza) Tx: erythromycin

76
Q

Pseudomonas aeruginosa Diseases?

A

Associated w/ wound and burn infxn PSEDUO Pneumonia (esp. in CF) Sepsis (black lesions on skin) Exteral otitis (swimmer’s ear) UTI Drug use Diabetic Osteomyelitis (+ hot tub folliculitis) *Think Pseudomonas in burn victims

77
Q

Pseudomonas aeruginosa classification and idenification

A

AERobic (AERuginosa) G(-) rod Non-lactose fermenting Oxidase (+) Produces pyocyanin (blue-green pigment) Has a grapelike odor Comes from water source

78
Q

Pseudomonas aeruginosa products

A

Endotoxin (fever, shock) Exotoxin A (inactivates EF-2)

79
Q

Pseudomonas aeruginosa Tx?

A

Aminoglycoside + extended-spectrum PCN (e.g., piperacillin, ticarcillin)

80
Q

Members of Enterobacteriacea

A

Diverse family including: E. coli Salmonella Shigella Klebsiella Enterobacter Serratia Proteus

81
Q

Commonalities among Enterobacteriaceae

A

All species have somatic (O) Ag (which is the polysaccharide of endotoxin). The capsular (K) Ag is related to the virulence of the bug. The flagellar (H) Ag is found in motile species. All ferment glucose and are oxidase (-) COFFEe Capsular (K) O Ag Flagellar Ag (H) Ferment glucose Enterobacteriaceae

82
Q

Klebsiella causes…

A

Pneumonia in alcoholics and diabetics (red currant jelly sputum) Also a cause of nosocomial UTIs relates to the 4 A’s: Aspiration pneumonia Abscess in lungs Alcoholics di-A-betics

83
Q

Salmonella typhi

A

Causes typhoid fever: diarrhea, HA, rose spots on abdomen. Can remain in gallbladder chronically.

84
Q

Salmonella vs. Shigella

A

Both: Lactose non-fermenters Invade the intestinal mucosa and can cause bloody diarrhea Only Salmonella: Has flagella, and can spread hematogenously (like how Salmon swim), Produces H2S. Shigella: Do not have flagella, but can propel themselves while inside cells by actin polymerization Spread by 4 F’s: Food, Fingers, Feces, and Flies Is more virulent (10 organisms infective vs. Salmonella: 100,000)

85
Q

Salmonellosis

A

Sx may be prolonged w/ ABX treatments There is typically a monocytic response

86
Q

Yersinia enterocolitica

A

Usually transmitted from pet feses (e.g., puppies), contaminated milk, or pork. Outbreaks are common in day-care centers. Sx can mimic Crohn’s or appendicitis.

87
Q

Helicobacter pylori Causes…? Is a risk factor for…?

A

Causes: Gastritis and up to 90% of duodenal ulcers Risk factor for: peptic ulcer, gastric adenocarcinoma, and lymphoma

88
Q

Helicobacter pylori Classification/identification

A

G(-) Rod. Urease (+) –> creates alkaline environment.

89
Q

Helicobacter pylori Tx?

A

Triple-therapy (two regimens): 1.) Bismuth (Pepto-bismol), metronidazole, and either TCN or amoxicillin 2.) Metronidale, omeprazole, and clarithromycin (*more costly option)

90
Q

Spirochetes

A

Spiral-shaped w/ axial filaments. Include: Borellia (big size) Leptospira Treponema (BLT. B is Big) Only Borrelia can be vizualized w/ aniline dyes (Wright’s or Giemsa). Treponema is vizualized w/ dark-field microscopy.

91
Q

Leptospira interrogans

A

Question mark-shaped bacteria found in water contaminated w/ animal urine. Causes: Leptospirosis - (flu-like Sx, fever, HA, abdominal pain, jaundice. Most prevalent in tropics) Weil’s dz (ictohemorrhagic leptospirosis) - severe form w/ jaundice and azotemia from liver and kidney dysfxn; fever, hemorrhage, and anemia

92
Q

Treponemal diseases

A

Treponemes are spirochetes. Treponema pallidum: Causes syphilis Treponema pertenue: Causes yaws; Infxn of skin, bone, and joints –> healing w/ keloids –> severe limb deformities Dz of the tropics. Not an STD, but VDRL positive.

93
Q

Syphilis Cause? Tx?

A

Caused by Treponema pallidum Tx w/ PCN G

94
Q

Primary syphilis

A

Presents w/ painless chancre (localized dz) Many treponemes present in chancre.

95
Q

Secondary syphilis

A

Disseminated dz w/ constitutional Sx’s, macupapular rash (palms and soles), condylomata lata. Many terponemes are present in condylomata lata. S econdary Sy philis = Sy stemic

96
Q

Tertiary syphilis

A

gummas (chronic granulomas), arotitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis), Argyll Robertson pupil (small pupils that accomodate but do not constrict/react [according to wikipedia, known as prostitutes pupils b/c they accomodate, but don’t react - not sure what that means) Signs: Broad-based axilla Positive Romberg Charcot joints Stroke w/o HTN

97
Q

Congenital syphilis

A

CN VIII deafness Saber shins (outward curve like a saber) Saddle nose Hutchinson’s teeth (smaller and more widely spaced)

98
Q

Argyll Robertson Pupil

A

Constricts w/ accomodation but is not reactive to light. Associated w/ tertiary syphilus. Prostitute’s Pupil - accomodates but does not react (???)

99
Q

VDRL vs. FTA-ABS

A

FTA-ABS is specfifc for treponemes, turns (+) earlies in dz, and remains (+) longest. VDRL and FTA-ABS: (+) result means active infxn (+) VDRL: Probably a false positive (+) FTA: Successfully treated FTA-ABS = Find The Ab ABSolutely: 1.) Most specific 2.) Earliest (+) 3.) Remains (+) longest

100
Q

VDRL False Positives

A

VDRL detects nonspecifc Ab that reacts w/ beef cardiolipin. Used for Dx of syphilis, but many biologic false positivies. Sources of false positives –> VDRL V iruses (mono, hepatitis) D rugs R heumatic fever L upus and L eprosy

101
Q

List of zoonotic bacteria

A

Big Bad Bugs From Your Pet named Ella B artonella henselae B orrelia burgdorferi B rucella spp. F rancisella tularensis Y ersinia pestis P asteurella multocida

102
Q

Bartonella henselae Disease? Transmission?

A

Causes: cat scratch fever Transmission: cat scratch

103
Q

Borrelia burgdorferi Disease? Transmission?

A

Causes: Lyme disease transmission: Tick bite; Ixodes ticks that live on deer and mice

104
Q

Brucella spp. Disease? Transmission?

A

Causes: Brucellosis / undulant fever Transmission: Dairy products, contact w/ animals Un pasteurized dairy gives you Un dulant fever.

105
Q

Francisella tularensis Disease? Transmission?

A

Causes: Tularemia Transmission: Tick bite; rabbits, deer

106
Q

Yersinina pestis Causes? Transmission?

A

Causes: Plague Transmission: Flea bite; rodents (esp. prairie dogs)

107
Q

Pasteurella multocida Disease? Transmission?

A

Causes: Cellulitis Transmission: Animal bit; cats, dogs

108
Q

Gardnerella vaginalis Microscopic appearance? Causes ….? Tx?

A

Pleomorphic, gram-variable rod. Causes vaginosis (off-white/gray vaginal discharge w/ fishy smell; nonpainful) Mobiluncus (an anaerobe) is also involved. Vaginosis is associated w/ sexual activity, but is not an STD. Bacterial vaginosis is characterized by overgrowth of certain bacteria in vagina. Clue cells seen. Tx for vaginosis: metronidazole

109
Q

Clue cells

A

Seen in bacterial vaginosis Vaginal epithelial cells covered w/ bacteria

110
Q

Rickettsiae Metabolism? Disease? Tx?

A

Obligate intracellular organisms Need CoA and NAD All except Coxiella are transmitted by an arthropod vector and cause HA, fever, and rash. Coxiella is an atypical rickettsia b/c it is transmitted by aerosol and causes pneumonia. Tx for most rickettsial infxns: TCN

111
Q

Classic triad for rickettsial infxns

A

HA, fever, rash (vasculitis)

112
Q

Rickettsia rickettsii Disease? Transmission? Tx?

A

Causes Rocky Mountain spotted fever Transmission via tick Tx: TCN

113
Q

Ricketsia typhus dz? transmission? Tx?

A

Causes endemic typhus Transmission via fleas Tx: TCN

114
Q

Rickettsia prowazekii Dz? Transmission? Tx?

A

Causes epidemic typhus Transmission via human body louse Tx: TCN

115
Q

Ehrlichia Dz? Transmission? Tx?

A

Causes Ehrlichiosis Transmission via tick Tx: TCN

116
Q

Coxiella burnetti Dz? Transmission? Tx?

A

Causes Q fever Q fever is Queer b/c it has no rash, no vector, and has negative Weil-felix, its causative roganism can survive outside for a long time, and does not have Rickettsia as its genus name. Transmission via inhaled aerosols Tx: TCN

117
Q

Rickettsial rash vs. Typhus rash

A

Rickettsial rash starts on hands and feet; Typhus rash starts centrally and spreads out: R ickettisa on the wR ists, T yphus on the T runk.

118
Q

Rocky Mountain Spotted Fever

A

Caused by Rickettsia rickettsii Sx: rash on palms and soles (migrating to wrists, ankles, then trunk), HA, fever. Endemic to East Coast (in spite of its name).

119
Q

Palm and sole rash

A

Seen in: C oxsackievirus A infxn (hand, foot, and mouth dz) R ocky Mountain spotted fever S yphilis (You drive CARS using your palms and soles)

120
Q

Weil-Felix Reaction

A

Assays for anti-rickettsial Abs, which cross-react w/ Proteus Ag. Weil-Felix is usually positive for typhus and Rocky Mountain spotted fever, but negative for Q fever.

121
Q

Chlamydiae

A

Cannot make their own ATP –> obligate intracellular organisms Cause mucosal infxns Chlamydial cell wall is unusual in that it lacks muramic acid Cell cycle w/ 2 forms: elementary body and initial/reticulate body

122
Q

Lab Dx, Tx for Chlamydiae infxns

A

Dx: cytoplasmic inclusions seen on Giemsa or fluorescent Ab-stained smear Tx: erythromycin or TCN

123
Q

Chlamydiae: Elementary body

A

Small, dense. E lementery E nters cells via endocytosis.

124
Q

Chlamydiae: Initial or Reticulate body

A

R eticulate body R eplicates in cell by fission

125
Q

Chlamydia trachomatis Causes…? Tx?

A

Causes: reactive arthritis conjunctivitisd nongonococcal urethritis pelic inflammatory dz (PID) As with all Clamydiae, Tx w/ erythromycin or TCN

126
Q

Chlamydia pneumoniae Disease? Transmission?

A

Causes atypical pneumonia Transmitted by aerosol As w/ all Chlamydiae, Tx w/ erythromycin or TCN

127
Q

Chlamydia psittaci Disease? Transmission?

A

Causes atypical pneumonia Transmission by aerosol *notable for avian reservoir As w/ all Chlamydiae, Tx w/ erythromycin or TCN

128
Q

Chlamydia trachomatis serotypes A, B, and C

A

Chronic infxn, cause blindness in Africa (ABC = Africa / Blindness / Chronic Infxn)

129
Q

Chlamydia trachomatis types D-K

A

Urethritis/PID Ectopic pregnancy Neonatal pneumonia Neonatal conjunctivitis* Neonatal dz can be acquired during passage thru infected birth canal Tx: oral erythromycin

130
Q

Chlamydia trachomatis serotypes L1, L2, and L3

A

Lymphogranuloma venerum (Acute lymphadenitis - positive Frei test) L 1-3 = L ymphogranuloma venerum

131
Q

Mycoplasma pneumoniae Causes…? Epidemiology of dz?

A

Classic cause of atypical walking pneumonia (insidious onset, HA, nonproductive cough, diffuse interstitial infiltrate) Mycoplasmal pneumonia is more common in pts < 30 years of age. Frequent outbreaks in military recruits and prisons.

132
Q

Mycoplasma pneumoniae Info on bacterium?

A

No cell wall. Not seen on gram stain. Only bacterial membrane containing cholesterol. Grown on Eaton’s agar.

133
Q

Mycoplasmal pneumonia Dx and labs? Tx?

A

X-ray looks worse than pt (walking pneumonia w/ diffuse interstitial infiltrate) High titer cold agglutinins (IgM) Tx: TCN or erythromycin (bugs are naturally PCN-resistant b/c they have no cell wall)

USMLE1 - Microbiology (7 decks)

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