Usmle Microbiology: Gram-Negative Bacteria

Front 1

Gram-Negative Cocci

Back 1

Neisseria spp.
Gram-Negative Rods (everything else)

Front 2

Bordetella pertussis Disease Features

Back 2

Whooping cough, dry hacking cough
Incubation - asymptomatic
Catarrhal - cold symptoms (best culture)
Paroxysmal - clinical whoops (less culture)
Convalescent - getting better, secondary infection (damaged cilia)

Front 3

Bordetella pertussis Identification

Back 3

1. Oxidase positive coccobacillus with capsule.
2. Grows on Regan-Lowe.
3. Clinical "whoop"

Front 4

Bordetella pertussis Pathogenic Factors

Back 4

1. A-B toxin; Increases cAMP
2. Hemagglutinin (attachment to ciliated endothelial cells -> further complications)
3. Tracheal cytotoxin

Front 5

Escherichia coli Disease Features

Back 5

1. ETEC traveler's diarrhea (watery)
2. EPEC pediatric diarrhea
3. EIEC (invasive) watery/bloody diarrhea (bacterial dysentery)
4. EHEC (non-invasive) watery/blood diarrhea O157:H7, hemolytic uremic syndrome in children

Front 6

Escherichia coli Identification

Back 6

1. Oxidase (-)
2. Lactose (+) -> Appearing purple on MacConkey Agar

Front 7

Escherichia coli Pathogenic Factors

Back 7

1. ETEC - two enterotoxins increasing cAMP,
2. Endotoxin (LPS)
3. Adhesions

Front 8

Haemophilus ducreyi Disease Features

Back 8

Painful genital ulcer

Front 9

Haemophilus influenzae Disease Features

Back 9

1. Infantile meningitis
2. Pediatric epiglottitis
3. Otitis media (children and adults)
4. Bronchitis/Pneumonia (elderly, those with chronic pulmonary disease

Front 10

Haemophilus influenzae Identification

Back 10

1. Coccobacillus
2. Catalase (+)
3. Factor X (heme) and factor V (NAD) needed for growth

Front 11

Haemophilus influenzae Pathogenic Factors

Back 11

1. Endotoxin (LPS)
2. Capsule (Hib vaccine)

Front 12

Klebsiella pneumoniae Disease Features

Back 12

Pneumonia (especially in alcoholics and those with poor lung function) CURRENT JELLY sputum

Front 13

Klebsiella pneumoniae Identification

Back 13

1. Lactose fermenter
2. Mucoid-appearing colonies in culture

Front 14

Klebsiella pneumoniae Pathogenic Factors

Back 14

Large antiphagocytic capsule

Front 15

Legionella pneumophila Disease Features

Back 15

1. Legionnaire's disease: atypical pneumonia (smoking history) caused by inhalation of water
2. Pontiac fever: self-limited, febrile illness

Front 16

Legionella pneumophila Identification

Back 16

1. Coccobacillus 2. Facultative intracellular 3. BYCE agar (need cysteine and iron)

Front 17

Legionella pneumophila Pathogenic Factors

Back 17

1. Growth in macrophages 2. Degradative enzymes kill parasitized cells

Front 18

Neisseria gonorrhoeae Disease Features

Back 18

Male (more likely to present) - urethritis, pus
Female - PID, endocervitis
Infants - opthalmia - leads to blindness if untreated

Front 19

Neisseria gonorrhoeae Identification

Back 19

1. Diplococcus
2. Ferments glucose (NOT maltose)
3. Growth on Thayer-Martin or chocolate agar

Front 20

Neisseria gonorrhoeae Pathogenic Factors

Back 20

1. Pili
2. Endotoxin (LPS)

Front 21

Neisseire meningitidis Disease Features

Back 21

1. Meningitis - fever, stiff neck, vomitting
2. Meningococcemia - petechial/purpura rash, septicemia, and WATERHOUSE-FRIDERICHSEN SYNDROME - hemorrhagic destruction of the adrenal glands (rapid)

Front 22

Neisseire meningitidis Identification

Back 22

1. Diplococcus
2. Capsule
3. Ferments glucose AND maltose
4. Growth on Thayer-Martin or chocolate agar

Front 23

Neisseire meningitidis Pathogenic Factors

Back 23

1. Capsule 2. Endotoxin (LPS) 3. Individuals deficit in C5-C8

Front 24

Proteus mirabilis Disease Features

Back 24

UTI

Front 25

Proteus mirabilis Identification

Back 25

1. Swarming growth on agar
2. Motile
3. H2S producer

Front 26

Pseudomona aeruginosa Disease Features

Back 26

1. Pulmonary infection (ventilator)
2. Hot tub folliculitis
3. Burn wounds - very susceptible
3. UTI
4. Ear (swimmer's ear) eye (corneal ulcers from contact lens)
5. Endocarditis

Front 27

Pseudomona aeruginosa Identification

Back 27

1. Motile
2. Oxidase (+) Lactose (-)
3. Aerobic
4. Fruity odor and Blue-green pigment

Front 28

Pseudomona aeruginosa Pathogenic Factors

Back 28

1. Exotoxin A - inhibit elongation factor EF2
2. Endotoxin (LPS)
3. Capsule
4. Tissue hydrolases

Front 29

Salmonella spp. Identification

Back 29

1. Motile
2. Oxidase (-)
3. Lactose (-)
4. H2S

Front 30

Salmonella enteritidis Disease Features

Back 30

Gastroenteritis with vomiting, watery/bloody diarrhea
Sepsis in sickle cell

Front 31

Salmonella enteritidis Pathogenic Factors

Back 31

1. Capsule 2. Exotoxin 3. Intracellular growth

Front 32

Salmonella typhi Disease Features

Back 32

Typhoid fever: 1. Increasing fever 2. Constipation 3. Septicemia 4. Gallbladder/Liver involvement

Front 33

Salmonella typhi Pathogenic Factors

Back 33

1. Capsule 2. Invasion of M cells of Peyer patches

Front 34

Shigella spp. Disease Features

Back 34

Shigellosis (bacterial dysentery): Watery/bloody stools, pus, fever and abdominal pain
Hemolytic uremic syndrome in children

Front 35

Shigella spp. Identification

Back 35

1. Non-motile
2. No H2S
3. Lactose (-) colorless on MacConkey

Front 36

Shigella spp. Pathogenic Factors

Back 36

1. Invades immune cells in Peyer's patches
2. A-B exotoxin (Shiga toxin) that inhibits protein synthesis