Article 2: Major Groups of Disease-Causing Bacteria (Article)

Question 1

Aerobic Gram-Positive Rods (3 important genera)

Answer 1

Bacillus, Corynebacterium, and Listeria

Question 2

Two medically important genera that produce spores

Answer 2

Bacillus and Clostridium

Question 3

Bacillus anthracis (Morphology, Spore Production, Motility, Unique Properties)

Answer 3

Large: end-to-end chains, Yes, No, Poly-D-glutamic acid capsule; spores

Question 4

Bacillus cereus (Morphology, Spore Production, Motility, Unique Properties)

Answer 4

Large, Yes, Yes; 50% of strains, Spores

Question 5

Corynebacterium diphtheriae (Morphology, Spore Production, Motility, Unique Properties)

Answer 5

Small and narrow, No, No, Pleomorphic; Chinese Characters (divides via snapping fission)

Question 6

Listeria monocytogenes (Morphology, Spore Production, Motility, Unique Properties)

Answer 6

Small, No, Yes; tumbling motion, Grows at 3-4 degrees C; grows intracellulaly

Question 7

Anaerobic Spore-Forming Gram-Positive Rods

Answer 7

Clostridium (only genus)

• Produce endospores to survive adverse conditions
  e. g. C. botulinum, C. tetani, C. perfringens, C. difficile

Question 8

Clostridium botulinum

Answer 8

• Fastidious spore-forming gram-positive rod shaped organism
• Production of a NEUROTOXIN results in disease (i.e. flaccid paralysis)
• Commonly isolated in SOIL and WATER

Question 9

Clostridium tetani

Answer 9

• Tennis rackt/drumstick appearance due to terminal ENDOSPORE
• Difficult to grow in vitro due to extreme OXYGEN SENSITIVITY
• Production of a NEUROTOXIN (tetanospasmin) causes spastic paralysis (i.e. lockjaw, arching of back, and respiratory muscle spasms)
• Commonly found in SOIL

Question 10

Clostridium perfringens

Answer 10

• Hemolytic and produces several toxins (alpha, beta, epsilon, and iota)
• Grows rapidly in tissue and in culture
• NOT motile (unlike other Clostridia)
• Cellulitis, suppurative myositis, gas gangrene, food poisoning

Question 11

Clostridium difficile

Answer 11

• Associated with prior antibiotic use and other chemotherapies
• Extremely sensitive to oxygen
• WATERY DIARRHEA

Question 12

Gram-Positive Cocci

Answer 12

Staphylococcus, Streptococcus, and Enterococcus

Question 13

Staphylocci

Answer 13

Catalase POSITIVE and grow in large clusters

• Grow in media with up to 10% salt
• Aerobic or anaerobic
• Found on skin and mucous membranes

Question 14

Streptococci

Answer 14

Catalase NEGATIVE and grow in chains

Question 15

Enterococcus

Answer 15

Catalase NEGATIVE and is in the Lancefield D group

Question 16

Staphylococcus aureus (Hemolysis, Catalase, Coagulase/Mannitol fermentation, Novobiocin)

Answer 16

Beta or gamma, Positive, Positive/Positive, Sensitive

Question 17

Staphylococcus epidermidis (Hemolysis, Catalase, Coagulase/Mannitol fermentation, Novobiocin)

Answer 17

Gamma, Positive, Negative/Negative, Sensitive

Question 18

Staphylococcus saprophyticus (Hemolysis, Catalase, Coagulase/Mannitol fermentation, Novobiocin)

Answer 18

Gamma, Positive, Negative/Negative, Resistant

Question 19

S. aureus

Answer 19

• Coagulase POSITIVE
• Most pathogenic and causes several diseases (e.g. food poisoning, toxic shock syndrome, scalded skin syndrome, impetigo/bullous impetigo, folliculitis, furuncles or boils, carbuncles, bacteremia and endocarditis, pneumonia and empyema, osteomyelitis, and septic arthritis)
• Produces a golden pigment

Question 20

S. epidermidis

Answer 20

• Coagulase NEGATIVE
• ubiquitous inhabitant of human skin
• forms biofilm on implanted medical devices (catheters, prosthetic joints, and heart valves)

Question 21

S. saprophyticus

Answer 21

• Coagulase NEGATIVE
• novobiocin resistant
• Second most common cause of UTI in sexually active young women (ages 13 to 40 y.o.) following E. coli

Question 22

Streptococcus pyogenes (Lancefield grouping, Hemolysis, Biochemical tests)

Answer 22

A (GAS), Beta, Sensitive to Bacitracin (A disc)

Question 23

Streptococcus agalactiae (Lancefield grouping, Hemolysis, Biochemical tests)

Answer 23

B (GBS), Beta usually; sometimes Gamma, CAMP test positive; hippurate hydrolysis

Question 24

Streptococcus pneumoniae (Lancefield grouping, Hemolysis, Biochemical tests)

Answer 24

Nongroupable, Alpha; Viridians group, Soluble in bile; Sensitive to Optochin (P disc)

Question 25

Streptococcus pyogenes

Answer 25

Uniquely sensitive to Bacitracin compared to other beta hemolytic streptocci Wide variety of diseases: -Pharyngitis "strep throat", Scarlet fever, Impetigo, erysipelas, cellulitis, necrotizing fasciitis, Streptococcal Toxic Shock Syndrome, Bacteremia, Sepsis, Cross-reactive antigen or immune complex disease (e.g. Rheuamtic fever, Acute glomerulonephritis)

Question 26

Streptococcus agalactiae

Answer 26

Produces diffusible heat stable factor (CAMP factor) | Early onset disease, Late onset disease, Adult diseases (UTIs and compromised adults)

Question 27

Streptococcus pneumoniae

Answer 27

LANCET-SHAPED or bull-shaped diplococcus

Question 28

Enterococcus

Answer 28

Catalase NEGATIVE

Question 29

Enterococcus faecalis and faecium

Answer 29

Both found in the GI or GU tract commonly | -Cause UTI, bacteremia, endocarditis, intra-abdominal abscesses

Question 30

Gram-Negative Bacteria: Gram-Negative Cocci

Answer 30

Neisseria - Two important species (N. meningitidis and N. gonorrhoeae) - Kidney bean-shaped; look like a coffee bean when two are lined up with their flattened sides

Question 31

Neisseria gonorrhoeae (Shape, Oxidase reaction, Acid via oxidation of carbohydrate, Media Requirements)

Answer 31

Diplococcus, Positive, Glucose only, Chocolate and Thayer-Martin agar

Question 32

Neisseria meningitidis (Shape, Oxidase reaction, Acid via oxidation of carbohydrate, Media Requirements)

Answer 32

Diplococcus, Positive, Glucose and Maltose, Blood or chocolate agar

Question 33

Enteric Gram-Negative Rods

Answer 33

Enterobacteriaceae: - Eschericia (rod shaped) - Salmonella (rod shaped) - Shigella (rod shaped) - Yersinia (rod shaped) Non-Enterobacteriaceae: - Vibrio (comma shaped rod) - Campylobacter (comma shaped rod or S-shaped rod or corkscrew) - Helicobacter (spiral shaped rod) - Bacteroides (rod shaped; ONLY OBLIGATE ANAEROBE)

Question 34

Non-Enteric Gram-Negative Rods

Answer 34

Klebsiella (found in GI tract) Haemophilus and Legionella (respiratory pathogens) Francisella (ticks, black flies, rabbit skinning) Pasteurella (animal bites) Brucella (unpasteurized/imported dairy products) Yersinia pestis (flea bites) Rickettsia (tick bites)

Question 35

What two Non-Enteric Gram-Negative Rods are opportunistic infections (require a defect in the patients' immune functioning)?

Answer 35

Pseudomonas and Kelbsiella