Bacterial infections-Andrews/Bolognia

Question 1

Why do gram positive bacteria stain purple/violet?

Answer 1

Thick layer of Peptidoglycan in the cell wall does not let crystal violet wash out

Question 2

What is beta hemolysis?

Answer 2

complete lysis of red cells surrounding the colony

Question 3

What is alpha hemolysis?

Answer 3

partial or “green” hemolysis associated with reduction of red cell hemoglobin.

Question 4

Is group A strep usually beta or alpha hemolytic?

Answer 4

Beta hemolytic

Question 5

A painful, erythematous nodule with pale center located on fingertips, thenar, and hypothenar eminences in bactremia/septicemia/endocarditis?

Answer 5

Osler Node (OUCHY)-From immune complex deposition and small vessel vasculitis

Question 6

A non-tender, angular hemorrhagic lesions on palms and soles in bactremi/septicemia/endocarditis?

Answer 6

Janeway lesions-septic emboli forming microabscesses

Question 7

What is the pathogenesis of community acquired MRSA?

Answer 7

Altered penicillin binding protein (PBP) called PBP2a-site where antibiotics bind to interrupt cell wall,
Virulence-Panton-valentine leukocidin (PVL)-Pore forming cytotoxin – can cause destruction of leukocytes and tissue necrosis

Question 8

What is the most common cause of folliculitis? Associated with swimming pools and jacuzzi’s? Associated with long term antibiotic therapy such as for acne or rosacea?

Answer 8

Staph aureus, pseudomonas, gram-negatives

Question 9

What is the name for a superficial folliculitis? Deep folliculitis?

Answer 9

Bockhart’s impetigo, sycosis barbae

Question 10

What is the most common causes of pygenic paronychia if there is abscess formation? If erythema and swelling? Chronic swelling?

Answer 10

Staph Aureus, Strep pyogenes, candida

Question 11

What is the Splendore-Hoeppli phenomenon

Answer 11

granule consisting of non-filamentous bacteria in a hyaline matrix w/ IgG and Complement C3 in “bunch of grapes” cluster,eosinophilic periphery with basophilic center in Botryomycosis?

Question 12

What is the most common cause of botryomycosis?

Answer 12

Staph Aureus

Question 13

What is the most common cause of pyomyositis? What is the most common location in kids and in the tropics? Most common location in temperate areas, HIV, DM, IVDA?

Answer 13

Staph aureus, thigh, deltoid

Question 14

In impetigo contagiosa what types are related to nephritis?

Answer 14

M type 2

Question 15

In bullous impetigo what causes the reaction?

Answer 15

exfoliative toxins A & B - S. aureus, group 2 phage type 71 (or 55); that bind to desmoglein 1 on the extracellular domain

Question 16

What causes staph scalded skin syndrome?

Answer 16

S. Aureus exfoliative toxins A & B from group 2 phage strains 55 & 71 bind to desmoglein 1

Question 17

What causes toxic shock syndrome?

Answer 17

S. Aureus exotoxin (TSST-1 toxin) superantigen or group A strep M types 1 & 3-exotoxin A 80% of the time

Question 18

What causes scarlet fever?

Answer 18

Exotoxin via group A b-hemolytic strep types A, B, and C that leads to a delayed hypersensitivity rxn

Question 19

What is Fournier’s gangrene?

Answer 19

Localized type of necrotizing fasciitis (type 1-polymicrobial) of scrotum or penis

Question 20

What is Meleney’s gangrene?

Answer 20

polymicrobial necrotizing faciitis as a complication to surgical trauma

Question 21

What are the tree types of necrotizing fasciitis?

Answer 21

Type I – polymicrobial
TypeII – group A streptococcal
Type III – gas gangrene or clostridial myonecrosis

Question 22

What streptococcal species is common cause of meningitis and sepsis in the neonate?

Answer 22

Strep agalactiae

Question 23

What streptococcal species would you be concerned about in the hands of a fisherman?

Answer 23

Streptococcus iniae

Question 24

If you saw purple swelling in the finger webs but sparing the phalanges in a fishermen what would you be thinking?

Answer 24

Erysipeloid of Rosenbach caused by Erysipelothrix rhusiopathiae

Question 25

What is the pathogenesis of bacillus anthracis?

Answer 25

Polyglutamic acid capsule -- inhibits phagocytosis Two EXOTOXINS: Edema toxin= Edema Factor (EF) + Protective Antigen (PA) Affects water homeostasis leading to edema through increased cAMP levels Lethal toxin = Lethal Factor (LF) +PA Causes shock and death by realease of TNF -alpha and IL-1beta

Question 26

In erythrasma what causes the coral-red fluorescence w/ Wood’s lamp (365 nm)?

Answer 26

Coproporphyrin III

Question 27

What causes erythrasma?

Answer 27

Corynebacterium minutissimum

Question 28

What causes pitted keratolysis?

Answer 28

Corynebacterium; Kytococcus (Micrococcus) sendentarius-Elaborates serine proteases K1 and K2  keratin-degrading serine proteases that destroy the S.Corneum

Question 29

What causes trichomycosis axillaris?

Answer 29

Corynebacteria tenuis

Question 30

What is the mechanism that causes gas gangrene?

Answer 30

α-toxin – biological activity similar to phospholipase C and sphingomyelinase Perfringolysin – disrupts endothelial cell integrity, impairs recruitment of phagocytes, and induces intravascular platelet aggregation from C. perfringens (most common)

Question 31

What do you use to treat actinomyces? Nocardia?

Answer 31

SNAP-Sulfa(bactrim) for nocardia, actinomyces use penicillin G

Question 32

What is the strongest risk factor for recurrence of erysipelas/cellulitis in the lower extremity?

Answer 32

lymphedema

Question 33

What is catalase?

Answer 33

enzyme that serves to protect the cell from toxic effects of high concentrations of hydrogen peroxide (H2O2) by catalyzing its decomposition into molecular oxygen and water, without the production of free radicals

Question 34

What clinical feature helps you differentiate between sycosis barbae (vulgaris) from tinea barbae?

Answer 34

Tinea barbae never involves the upper lip where sycosis barbae (vulgaris) usually does

Question 35

Differential Dx of Slendore-Hoeppli immune complex deposition?

Answer 35

``` Actinomycosis Mycetoma Sarcoid Botryomycosis Sporotrichosis Nocardia ```

Question 35

What are pastia lines and it is associated with what?

Answer 35

accentuation over skin folds, linear petechial eruption, usually antecubital or axillary folds associated with Scarlet Fever

Question 36

What are pastia lines and it is associated with what?

Answer 36

accentuation over skin folds, linear petechial eruption, usually antecubital or axillary folds associated with Scarlet Fever

Question 38

What is the treatment for listeriosis?

Answer 38

AMPICILLIN or bactrim

Question 39

What is the differential for Splendore-Hoeppli phenomenon ?

Answer 39

``` Actinomycosis Mycetoma Sarcoid Botryomycosis Sporotrichosis Nocardia ```

Question 40

What is the criteria for diagnosing rheumatic fever?

Answer 40

Two major criteria, or one major and two minor criteria, and signs of a previous strep infection

Question 41

What are the major criteria in diagnosing rheumatic fever?

Answer 41

Arthritis in several joints (polyarthritis) Heart inflammation (carditis) Nodules under the skin (subcutaneous skin nodules) Rapid, jerky movements (chorea, Sydenham chorea) Skin rash (erythema marginatum)

Question 42

What are the minor criteria in diagnosing rheumatic fever?

Answer 42

Fever High ESR Joint pain Other laboratory findings