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Flashcards in Microbiology Deck (78):
1

Infectious agent without nucleus, without ribosomes, without mitochondria, and the outer surface composed of protein capsid and lipoprotein envelope

Virus

2

Infectious agent with prokaryotic nucleus, 70s ribosome, absent mitochondria, and outer surface is rigid wall containing peptidoglycan

Bacteria

3

Which microscopic characteristic primarily distinguishes prokaryotes from eukaryotes?
A. Relatively small size and absence of nuclear membranes
B. Presence of histone proteins in the nuclear area
C. Naked, circular chromosomes
D. Presence of subcellular structures

A. Relatively small size and absence of nuclear membranes

4

Mobile genetic elements

Transposons

5

Noncellular infectious proteins that lack nucleic acids?
A. Viruses
B. Bacteria
C. Viroids
D. Prions

D. Prions

Prions - noncellular infectious proteins that are resistant to nucleases, proteases, and many chemicals; associated with spongiform encephalopathies (Creutzfeldt-Jacob disease, Kuru disease, Bovine spongiform encephalopathy)

Viroids - obligate intracellular parasites of plants, with naked RNA, no known human disease

6

Gram-positive versus Gram-negative bacteria

Gram-Positive
- 2 layers - inner cytoplasmic membrane, outer thick peptidoglycan layer
- low lipid content
- with teichoic acid
- no endotoxin
- no periplasmic space
- no porin channel

Gram-Negative
- 3 layers - inner cytoplasmic membrane, thin peptidoglycan layer, outer membrane with lipopolysaccharide
- high lipid content
- with endotoxin
- with periplasmic space
- with porin channel

7

Lysozymes are enzymes that kill bacteria by cleaving which part of the cell wall?
A. Pentaglycine bridges
B. Multiple layers of peptidoglycan net
C. Beta 1 -> 4 glycosidic bond between NAG and NAM
D. Tetrapeptide side chains

C. Beta 1 -> 4 glycosidic bond between NAG and NAM

8

Only gram-positive bacteria with endotoxin

Listeria monocytogenes

9

Bacteria that are not seen in gram stain

These Rascals May Microscopically Lack Color
- Treponema (Leptospira, Borrelia)
- Rickettsia
- Mycobacterium
- Mycoplasma
- Legionella
- Chlamydia

10

Which component of the gram-negative cell wall is responsible for its nonspecific endotoxin activity?
A. Lipopolysaccharide
B. Teichoic acid
C. Peptidoglycan layer
D. Enzymes in the periplasmic space

A. Lipopolysaccharide

11

Which component of the gram-negative cell wall reduces its susceptibility to lysozymes?
A. Teichoic acid
B. Enzymes in the periplasmic space
C. Peptidoglycan layer
D. Outer membrane

D. Outer membrane

12

Only bacteria with a polypeptide capsule

Bacillus anthracis

13

Extrachromosomal, double-stranded, circular DNA capable of replicating independently of the bacterial chromosome

Plasmids

14

Phase of bacterial growth characterized by rapid cell division and constant growth rate
A. Lag phase
B. Log or exponential phase
C. Stationary phase
D. Decline or death phase

B. Log or exponential phase

Lag phase - depleted metabolites, zero growth rate
Log or exponential phase - rapid cell division and constant growth rate
Stationary phase - zero growth rate due to exhaustion of nutrients or accumulation of toxic products
Decline or death phase - negative growth rate

15

Enzymes required by obligate aerobes

Superoxide dismutase, Peroxidase, Catalase

16

Obligate anaerobes

Actinomyces, Bacteroides, Clostridium

17

Obligate aerobes

Nosy and Nagging Pests Must Breathe Lots of oxygen

Nocardia, Bacillus cereus, Neisseria, Pseudomonas, Bordetella, Legionella, Brucella, Mycobacterium, Leptospira, Mycpolasma pneumoniae

18

Facultative Anaerobe

Staphylococcus, Bacillus anthracis, Corynebacterium, Listeria, Mycoplasma spp

19

Microaerophiles

Streptococcus, Spirochetes (Borrelia, treponema), Campylobacter, Helicobacter

20

DNA transferred by a virus from one cell to another
A. Conjugation
B. Transduction
C. Transformation

B. Transduction

Conjugation - DNA is transferred from one bacterium to another via sex pili
Transduction - via bacteriophage
Transformation - naked DNA is taken up by a cell

21

Bacterial enzyme that allows adherence to mucous membranes?
A. Collagenase
B. Coagulase
C. IgA protease
D. Leukocidin

C. IgA protease

Collagenase and Hyaluronidase - allows spread of bacteria throught subcutaneous tissue
Coagulase - accelerates formation of a fibrin clot coating the organism with a layer of fibrin
Leukocidin - destroys neutrophilic leukocytes and macrophages

Bacteria with IgA proteas
SHine My Gong
- Streptococcus pneumoniae
- Haemophilus influenzae
- Neisseria meningitidis
- Neisseria gonorrhea

22

Only exotoxin that is heat stable

Staphylococcal enterotoxin

23

Gram-positive cocci, catalase positive, coagulase positive

Staphylococcus aureus

24

Gram-positive cocci, catalase positive, coagulase negative, novobiocin resistant

Staphylococcus saprophyticus

Staphylococcus epidermidis - novobiocin sensitive

25

Gram-positive cocci, catalase negative, Y-hemolytic, bile resistant, grows in 6.5%v NaCl

Enterococcus faecalis (Group D Streptococcus)

Streptococcus bovis (Nonenterococcus) - does not grow in 6.5% NaCl

26

Gram-positive cocci, catalase negative, A-hemolytic, optochin resistant

Streptococcus viridans

Streptococcus pneumoniae - optochin sensitive

27

Gram-positive cocci, catalase negative, B-hemolytic, bacitracin sensitive

Streptococcus pyogenes (Group A Streptococcus)

Streptococcus agalactiae (Group B Streptococcus) - bacitracin resistant

28

Pigment that causes the gold color of Staphylococcus aureus

Staphyloxanthin

29

Agar of Staphylococcus

Mannitol salt

30

Virulence factor of Staphylococcus aureus that prevents complement activation and opsonization

Protein A

Pantone Valentine Leukocidin - toxic to WBCs
Hemolysin - toxic to hematopoietic cells (neutrophils, macrophages, platelets)
Penicillinase - inactivates penicillin derivates

31

Exotoxin of Staphylococcus aureus that causes epidermal separation in Scalded Skin Syndrome (Ritter disease)

Exfoliatin

32

Exotoxin of Staphylococcus aureus that causes food poisoning

Enterotoxin (heat stable)

33

Exotoxin of Staphyloccocus aureus that causes Toxic Shock Syndrome

Toxic Shock Syndrome Toxin 1

34

Vancomycin resistance in Staphylococcus aureus is carried in which gene?
A. mecA
B. vanA
C. blaZ
D. dfrB

B. vanA

mecA - Methicillin resistance

35

Drug of choice for vancomycin-resistant SA

Linezolid

36

Frequent skin contaminant of blood cultures and causes prosthetic valve endocarditis, septic arthritis in prosthetic joints, and VPS infections

Staphylococcus epidermidis

37

Second most common cause of UTI in sexually-active women

Staphylococcus saprophyticus

38

Differences between S. saprophyticus and E. coli

S. saprophyticus - gram-positive, nitrite-negative

E.coli - gram-negative, nitrite-positive

39

Exotoxin of Streptococcus pyogenes that destroys RBCs and WBCs

Streptolysin O and S

40

Exotoxin of Streptococcus pyogenes that is similar to TSS1 of Staphylococcus aureus

Pyogenic exotoxin A

41

Exotoxin of Streptococcus pyogenes that causes scarlet fever

Pyrogenic/Erythrogenic toxin

42

Exotoxin of Streptococcus pyogenes that facilitates Necrotizing fasciitis

Exotoxin B

43

Titers to document antecedent skin infection with Streptococcus pyogenes

Anti-DNAse

Anti-Streptolysin O - titers to document antecedent Streptococcal pharyngitis

44

Test for susceptibility for scarlet fever

Dick test

45

Diseases that present with strawberry tongue

Scarlet fever - Streptococcus pyogenes
Toxic Shock Syndrome - Staphylococcus aureus
Kawasaki disease

46

Symptoms of Acute Rheumatic Fever

Jones Criteria
- Polyarthritis
- Pancarditis
- Subcutaneous nodules
- Erythema marginatum
- Sydenham chorea

47

Antecedent infection of PSGN

Streptococcal pyoderma

ARF - Stretococcal pharyngitis

48

Three most common cause of meningitis in infants <3 mos

- E. coli
- Group B Streptococcus
- Listeria monocytogenes

49

Cause of marantic endocarditis in patients with abdominal malignancy

Streptococcus bovis

50

Encapsulated bacteria

Some Kilers Have Pretty Nice and Shiny Bodies
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Haemophilus influenzae
- Pseudomonas aeruginosa
- Neisseria meningitidis
- Salmonella typhi
- Group B Streptoccus

51

Most common cause of community-acquired pneumonia and presents radiographically as lobar pneumonia

Streptococcus pneumoniae

52

Three most common causes of otitis media

- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis

53

Streptococcus viridans associated with dental carries

Streptococcus mutans

54

Streptococcus viridans associated with subacute bacterial endocarditis (and the most common cause of subacute endocariditis and native valve endocarditis)

Streptococcus sanguis

55

Streptococcus viridans associated with brain abscess

Streptococcus intermedius

56

Spore-forming gram-positive rod

- Bacillus (aerobe)
- Clostridium (anaerobe)

57

Nonspore-forming gram-positive rod

- Listeria
- Corynebacterium

58

Malignant pustule with subsequent eschar and central necrosis

Cutaneous anthrax

59

Inhalation of Bacillus anthracis spores that leads to massively enlarged mediastinal lymph nodes pulmonary hemorrhage, and meningial symptoms

Inhalational anthrax or Woolsorter's disease

60

Drug of choice for Bacillus anthracis

Ciprofloxacin

61

Gene that encodes for the polypeptide (poly-glutamyl) capsule of Bacillus anthracis

pXO2

pXO1 - encodes for the exotoxins (edema factor, lethal factor, and protective antigen)

62

Food poisoning from reheated rice

Bacillus cereus

63

Protease that cleaves proteins involved in the relase of glycine from Renshaw cells in spinal cord leading to muscle spasm

Tetanospasmin or Tetanus toxin

64

Antibiotics for Clostridium tetani

Metronidazole of Penicillin

65

Neurotransmitter blocked by botulinum toxin

Acetylcholine

66

Paralysis of botulinum toxin

Flaccid paralysis (descending pattern)

67

Immunologic types of Clostridium botulinum that are most common in humans

A, B, E

68

Agar for Clostridium perfringens

Egg-yolk agar

69

Causative agent of gas gangrene

Clostridium perfringens

70

Causative agent of antibiotic-associated pseudomembranous colitis

Clostridium difficile

71

Antibiotic that is the most common cause of pseudomembranous colitis

Clindamycin

Other causes - second and third generation cephalosporins, ampicillin

72

Treatment for pseudomebranous colitis

Metronidazole or Vancomycin

73

Clostridia associated with septic abortion

Clostridium sordellii

74

Non-motile, non-spore forming gram-positive rod that causes pseudomembranes over tonsils and throat

Corynebacterium diphtheriae

75

Bacterias with beta-prophage or lysogenic exotoxin

- Shiga-like toxin (EHEC)
- Botulinum toxin
- Cholera toxin
- DIphtheria toxin
- Erythrogenic toxin (S. pyogenes)

76

Exotoxin of Listeria monocytogenes that helpst it evade phagosomes

Listeriolysin

77

Second most common cause of meningitis in adults

Listeria monocytogenes

Most common cause is Streptococcus pneumoniae

78

Listeriosis associated with late miscarriage or birth complicated by sepsis, multiorgan ascesses, and disseminated granuloma

Early-onset Neonatal Listeriosis or Granulomatosis Infanseptica