Bacterial, Viral, Fungal Infections I Flashcards Preview

Micro Post Midterm > Bacterial, Viral, Fungal Infections I > Flashcards

Flashcards in Bacterial, Viral, Fungal Infections I Deck (50):
1

initiation of infection: those that enter through bites/scratches

Streptococci., Mixed aerobic/anaerobic
bacteria, Pasteurella, many more species

2

initiation of infection: those that enter through trauma

Cellulitis, fasciitis, myonecrosis, bone inf.

3

causes of pasteurella multocida

deep skin infection, bacteriemia, endocarditis, osteomyelitis, septic arthritis

4

what is pasteurella multocida

primarily zoonotic and part of normal flora of upper RT

5

how does one get pasteurella multocida

via a cat or dog by bite or scratches, licking of broken skin,

6

infections in keratinized epithelium and epidermis

keratinized epithelium: dermatophytic fungi
epidermis: warts (HPV), impetigo (staph `aureus and group A strep), cold sores (HHV-1)

7

infections in dermis and hair follicles

dermis: cellulitis and erysipelas
hair follicles: folliculitis and abscesses

8

infection in sebaceous glands

acne (propionibacterium acne)

9

bacteria seen in hot tub folliculitis

pseudomonas

10

where is streptococci normal seens

as part of normal flora in oral cavity, GI, and genital tract

11

features of strep

gram positive cocci in chains, classified based on hemolysis on blood agar

12

features of strep pyogenes

gram positive, beta hemolytic, strep that form pus and can occasionally cause purulent infections, infections can be in upper skin layer or it can go deep

13

toxin of strep pyogenes

pyrogenic exotoxin (SPE) once called erythrogenic toxin
minority of strain carry this toxin which is carried on a phage

14

what does the pyrogenic exotoxin do

stimulates cytokine release causing multiple effects like: red rash on skin --> scarlet fever

15

how is pharyngitis spread

direct contact or aerosol

16

carrier rate of untreated pharyngitis and where it is located

1-4 weeks or more after infection as organisms in in throat and sometimes anus

17

type of infection is scarlet fever

group A beta strep infection

18

symptoms of scarlet fever

strep throat with a characteristic rash
deep red color cheeks, temples, buccal mucosa
strawberry tongue
punctuate hemorrhages on palate
sandpaper rash on trunks, arms, and legs

19

the exotoxin released from strep pyogenes can be attributed to what symptom in scarlet fever

sandpaper rash on trunks, arms, and legs

20

what is staph aureus

gram positive cocci found in clusters and in thick cell walls
often found intracellularly in granulocytes

21

cultural characteristics of staph aureus

grows on blood agar with aerobic conditions
white colony but can become yellow with age
usually beta hemolytic

22

positive for staph aureus in about 30% of population

anterior nares

23

virulence factors of staph aureus

coagulase, exotoxin, hemolysins, leukocidins

24

diseases caused by staph infections

scalded skin syndrome, S. aureus exfoliatins, toxic shock syndrome,

25

how does one get scalded skin syndrome

toxin is absorbed into the blood stream with erythema and intraepidermal desquamation occurring at remote sites

26

can staph aureus be isolated from desquamation sites of scalded skin syndrome

no

27

what is occurring staph aureus exfoliatins

exfoliatins are leading to intercellular splitting of the epidermis -- between the stratum spinosum and stratum granulosum by disruption of the intercellular junctions

28

in s. aureus exfolatins, if toxin is produced at the site of infection what happens

epithelial desquamation at the remote sites of the body --> staph scalded skin syndrome

29

what is toxic shock syndrome characterized by

high fever, vomiting, diarrhea, sore throat, muscle pain, shock within 48 hours with renal and hepatic damage

also skin rash, strawberry tongue

30

describe what happens after skin rash in toxic shock syndrome

desquamation at a deeper level than scalded skin syndrome

31

what is the toxin in toxic shock syndrome

pyrogenic toxin called toxic shock syndrome toxin-1 (TSST-1)

32

what does TSST-1 do

stimulates release of cytokines and direct toxic effects on endothelial cells

Stimulates enhanced T-lymphocyte responses by direct interaction with surface receptors on T cell.

33

situation where TSS is usually seen

when woman is menstruating and wears tampon for long periods of time -- provides environment for products of toxin which is absorbed from the local site (1 in 5 women have staph aureus as part of normal flora of vagina)

non menstrual TSS does occur

34

cause of impetigo and causative agent

insect bite or minor abrasion
staph aureus or group A strep

35

what is impetigo characterized by

–Small vesicles with erythema
–Become pustular and later crusted

36

complication of impetigo

post strep glomerulonephritis 2-4 weeks after skin infection but only if caused by strep pygogenes aka group A strep

37

what can occur after beta strep infections

acute rheumatic fever

38

what are characteristics of acute rheumatic fever

– Inflammatory disease
• Fever, carditis, subcutaneous nodules, migratory polyarthritis
– Heart valve damage
• Murmurs, cardiac enlargement.
• Repeat infections lead to progressive damage

CCSEA and P-FACE
chorea, carditis, subcutaneous nodules, erythematous marginatum, arthritis, pr elongation, fever, arthralgia, increased CRP and ESR

39

pathogenesis of acute glomerulonephritis

antigen-antibody complexes in the kidney (type III hypersensitivity)

40

what population acute glomerulonephritis after strep infection usually seen in

children

41

other than straph aureus what other organism can cause TSS

strep pyogenes

42

can staph aureus be found together strep pyogenes in impetigo

yeah in about 30% of cases

43

coagulase and catalase positive

staph aureus

44

is coagulase a toxin

no but it plays a role in its pathogenesis

45

coagulase -- what does staph coated with fibrin prevent

phagocytosis (helps localize the lesion)

46

other biological substances that staph aureus produces

Hemolysins, hyaluronidase, nuclease, lipase, protease

47

major cytotoxin of staph aureus

staph aureus alpha toxin

48

characteristic of alpha toxin

-- chromosomally encoded, low molecular weight protein
– Causes necrosis or death in experimental animals
-- Causes certain mammalian cell membranes to leak through pores formed by toxin
– Causes RBC’s to lyse.

49

what is panton valentine leukocidin (PVL)

it is a cytotoxin that lyses neutrophils and releases enzymes that damages host cells

50

what is PVL associated with

-severe pneumonia
-severe skin infections
-common in community acquired methicillin resistant strains