Bacterial, Viral, Fungal Infections II

Question 1

what is a furuncle

Answer 1

boils develop in hair follicles

-infections at base of eyelashes gives rise to styes

Question 2

carbuncles are associated with what conditions

Answer 2

chronic granulomatous disease and diabetes

Question 3

what is chronic granulomatous disease

Answer 3

genetic disorder where immune cells are unable to kill some types of bacteria/fungi
-disorder can lead to chronic/recurrent infections which is discovered in childhood

Question 4

large fluid filled pustules

Answer 4

bulla

Question 5

what is bullous impetigo caused by

Answer 5

staph aureus that produces exfolatin

Question 6

in bullous impetigo, what does the large blisters on the superficial layer of the skin contain

Answer 6

many staph

Question 7

common location of carbuncle

Answer 7

nape of the neck

Question 8

what is chronic furunculosis and what causes it

Answer 8

chronic boils/furuncles

due to delayed hypersensitivity of staph products (reason for most of the inflammation and necrosis)

Question 9

mode of transmission for rickettsii

Answer 9

insect bite

Question 10

pathogenesis of ricketsii

Answer 10

infects vascular endothelium which causes RBC leakage from breaks in vessels –> rash and petechial lesion

Question 11

insect in rickettsii ricketsiia aka rocky mountain fever and distribution of the rash

Answer 11

tick

centripetal: starts at wrist and goes to trunk then back out to palms and sole of feet

Question 12

louse borne typhus fever is caused by what

Answer 12

rickettsia prowazeki

Question 13

how is rickettsia prowazekii transmitted

Answer 13

body louse/lice

Question 14

how does the louse get and transmit typhus fever

Answer 14

it gets it from an infected person then once it bites someone else and defecates at site, it will die

Question 15

typhus fever is commonly seen when

Answer 15

disease of war and upheaval – epidemics in refugee

Question 16

how long does it take the rash to show up in typhus fever and describe the rash

Answer 16

10 days

it spares the palms of the hand and the soles of the feet – centrifugal

Question 17

complication of typhus fever

Answer 17

gangrene because of compromised circulation due to infection induced vascular injury

Question 18

how does one diagnose rickettsial disease

Answer 18

• PCR is best (atypical bacteria)
• enzyme immuno assays for antibody production
• culture is difficult and hazardous (requires tissue culture or eggs)

Question 19

transmission of primary classic lyme disease

Answer 19

tick bite - spirochete enters the skin

Question 20

what happens at the bite site of lyme disease

Answer 20

3-30 days later:
• Erythema chronicum migrans (ECM). –Slowly expanding red ring.
–Biopsy of leading edge contains organism.
–Disappears within weeks.
• Constitutional symptoms for months.
–Fever, muscle and joint pains.
–Meningeal irritation

Question 21

what is borrelia burgdorferi

Answer 21

spirochete shaped organism that is found in low amounts in tissues

Question 22

how to diagnose borrelia burgodorferi seen in lyme disease

Answer 22

EIA for antibody screen plus western blot for confirmation
PCR of joint fluid or biopsy of leading edge of new ECM rash
culture and stain are rarely productive

Question 23

inflammation of subcutaneous fat: cellulitis –> what are the organisms

Answer 23

– Streptococcus pyogenes
– Staphylococcus aureus
– Pasteurella multocida

Question 24

inflammation of fascia - fascitis –> what are the organisms

Answer 24

– Streptococcus pyogenes

– Polymicrobial

Question 25

myonecrosis/gangrene in muscles --> what is the organism

Answer 25

Clostridium perfringens

Question 26

presentation and microbiology of cellulitis

Answer 26

deeper dermis, subcutaneous tissue, fever, chills, bacteremia beta hemolytic strep, s. aureus

Question 27

presentation and microbiology of erysipelas

Answer 27

upper dermis, superficial lymphatics, fever, pain, lymphadenopathy, rapidly advancing edges of infection, often on face beta hemolytic strep, rarely s. aureus, group B strep

Question 28

big difference between staph and strep cellulitis

Answer 28

strep spread really fast | staph alternates between walling off and rapid extension of infection (so slow then fast then slow)

Question 29

what is erysipelothrix rhusiopathiae

Answer 29

gram positive diphtheroid like rod found in animals, meat, and sea food

Question 30

disease associated with erysipelothrix rhusiopathiae

Answer 30

erysipeloid which is a painful slowly spreading skin infection

Question 31

transmission of erysipelothrix rhusiopathiae and commonly seen in whom

Answer 31

traumatic inoculation of the skin | commonly seen in fishermen, butchers, veterinarians

Question 32

treatment of erysipeloid

Answer 32

penicillin and erythromycin

Question 33

major cause of wound infections

Answer 33

staph aureus

Question 34

sources of wound infections

Answer 34

patient's own strain | nosocomial strains spread by health care workers practicing poor hygiene (no hand washing)

Question 35

amount of organism needed to initiate s. aureus infection in wound infection

Answer 35

10^5 - 10^6

Question 36

amount of organism needed to initiate s. aureus infection in wound infection if at site of a suture

Answer 36

only 10^2 organisms

Question 37

what do coagulase negative staph lack

Answer 37

virulence factors of staph aureus non beta hemolytic grouped with normal flora

Question 38

how have coagulase negative staph become opportunistic pathogens

Answer 38

– Indwelling plastic and metal devices in seriously ill patients. – Immunosuppressed patients. – Major surgery involving large areas

Question 39

number one bacteria in CNS

Answer 39

staph epidermidis

Question 40

what does staph epidermidis produce

Answer 40

extracellular polysaccharide slime and biofilm

Question 41

what does staph epidermidis provide

Answer 41

adhesion to indwelling devices such a catheters, artificial heart valves, CSF shunts, hip replacements (because of the slime and biofilm)

Question 42

s. epidermidis provides provides biofilm for organisms hence protecting them from what?

Answer 42

phagocytosis and antibiotics | yet they can still obtain nutrients

Question 43

coagulase negative staph that causes infection similar to that of staph aureus minus the toxic shock syndrome

Answer 43

s. lugdunensis

Question 44

what does s. lugdunensis cause

Answer 44

serious infections which include abscess formation

Question 45

clinical significance of coagulase neg staph

Answer 45

- difficult to determine significance (few colonies are normal in superficial specimen) - hence have to collect deep invasive samples to avoid superficial contaminants

Question 46

when is coagulase neg staph considered significant

Answer 46

– Present in multiple blood cultures. – Intracellular Gram-positive cocci are seen in Gram stain. – Culture shows moderate to heavy numbers on culture plates from wound specimens

Question 47

when is coagulase neg staph considered less significant

Answer 47

• Negative plates with pos. broth culture only indicates very low #’s of CNS

Question 48

necrotizing fascitis is due to what bacteria

Answer 48

beta hemolytic group A strep