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Staph Lange reading Flashcards

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Dermatology Board Prep flashcards
1
Q

staph and strep belong to which genera

A

Gram positive cocci

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2
Q

staph aureus lab/culture findings

A 
Coag +
Catalase +
protein A on surface
beta hemolytic
GRAPE LIKE CLUSTERS
NON-MOTILE
NON-SPORE FORMING
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3
Q

Strep pyogenes Lab/culture findings

A 
Coag-
Catalase -
Beta Hemloytic
Lancefield group A
CHAINS
NON-MOTILE
NONSPORE FORMING
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4
Q

NAME THE COMUNITY ACQUIRED DISEASES STAPH CAN CAUSE

A 
ABCESSES
ENDOCARDITIS
SEPTIC ARTHRITIS
OSTEOMYELITIS
FOOD POISONING
SCALDED SKIN SYNDROME
TOXIC SHOCK SYNDROME
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5
Q

NAME THE HOSPITAL RELATED DISEASES STAPH A. CAN CAUSE

A

HOSPITAL ACQUIRED PNEUMONIA
SEPTICEMIA
SURGICAL-WOUND INFECTION

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6
Q

NAME THE SKIN INFECTION STAPH A. CAN CAUSE

A

IMPETIGO
FOLLICULITIS
CELLULITIS
BACTERIAL CONJUNCTIVITIS (MOST COMMON CAUSE)

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7
Q

CLASSIC LESION CAUSED BY STAPH. A

A

ABCESSES

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8
Q

impetigo is caused by

A

either staph A or strep pyogenes

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9
Q

more commonly, endocarditis and septic arthritis is caused by

A

staph epi–> white colonies–> no staphyloxanthin (virulence much less than staph aureus)

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10
Q

what does catalase do

A

degrades h202–> o2 and h20

*important virulence factor because H2O2 is a microbicidal and its degredation limits neutrophils ability to kill

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11
Q

Staph aureus is distinguished by what

A

Coagulase production

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12
Q

what does coagulase do?

A

causes plasma to clot by activating prothrombin to thriombin–> thrombin catalyzes fibrinogen to fibrin forming a fibrin clot—>retards neutrophil migration ot infection site

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13
Q

why is staph aureus colonies golden

A

staphyloxanthin carotenoid

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14
Q

what does staphyloxanthin do?

A

incativate microbicidal effect of superoxides and other ROS within neutrophils

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15
Q

hemolytic profile of staph aureus

A

SA hemolyses RBCS and ferments mannitol–> epi and saprophyticus do not
*hemolysis provides the bacteria with enough iron for growth (used to make cytochrome enzymes to prduce energy)

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16
Q

required agent for any bacterial growht in host

A

iron

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17
Q

Staph aureus reistance profiles

A

90% resistance to beta lactamases (plasmid)

20% resistant to beta lactamase resistant antibiotics (Nafcillin and Methicillin)–> thanks to a antered PBB–mecA gene)

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18
Q

what percentage of strains of staph in hospital pt.’s are MRSA/NRSA

A

50%

most common being US300 strain

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19
Q

how do STaph become vanc resistant

A

cassette of genes substitutes D-LAC/D-LAC for DLAC/DALA

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20
Q

Function of Protein A

A

major cell wall protein
*binds to Fc portion fo IgG and inhibtis compliment activation on mirobial surface–> NO C3b is made…opsonization and phagosytosis of the bacteria is greatly reduced

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21
Q

Function of Teichoic acids

A

mediate adherance to mucosal membranes

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22
Q

Funciton of lipoteichoic acids

A

induce septic shock by inducing Il1 and TNF from macrophages

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23
Q

which serotypes of Staph A. cause 85% of infection

A

serotypes 5 and *–> there are 11 in all

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24
Q

describe polysaccharide capsule of Staph A.

A

thin…microcapsule..poorly immunogenic–> vaccine therefore difficult

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25
Q

Describe the peptidoglycan wal of Sta. Aureus

A

endotoxin-liek properties–> can stimulate macs to produce cytokines and activate the compliment and coag cascades–> leading to septic shock even without a TRUE ENDOTOXIN

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26
Q

Name the virulence factors for Staph Aureus

A 
Protein A
Hemolysis
Teichoic Acids
Lipoteichoic acids
capsule
peptidoglycan wall with endotoxin-like characteristics
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27
Q

main sites of colonization for Staph A

A

nose–> 30% are colonized
5% in the vagina–> predisposes to TSS
*skin of hospital personnel is a major reservoir
Fomites–> dirty towels

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28
Q

reduciton in transmission of Staph aureus

A

hand washing!!!

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29
Q

important predisposing factors to staph infection

A

sutures
catheters
family member with boils
low humoral immunity (t cells, compliment and antibodies)
chronic granulomatous disease (defective neutrophil killing of bacteria)

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30
Q

name the three clinically important toxins and enzymes produced by staph aureus

A

Enterotoxin–> food poisoning and Non-Bloody D
Toxic Shock Syndrome Toxin–> TSS
Exfoliatin–> Scalded Skin syndrome

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31
Q

Describe what enterotoxin does?

vomiting more prominent than diarrhea when Staph aureus is involved

A

IN the Gi tract-> acts as a superantigen to activate IL1 and IL2 from macs and T cells respectively–>
Vomiting-> cytokines released from lymphoid cells acting on enteric nervous system to activate Vomit center in brain
Enterotoxin-> heat resistant, type A-f, acid resistant

32
Q

describe A super antigen

A 
class of antigens that cause non-specific activation of T cells leadin to polyclonal T cell expansion and massive cytokine release
*can activate 25% of t cell population and not bound to any specific eliciting antigen
33
Q

who gets TSS

A

menstruating women with tampon use or individuals with wound infections, nasal packing

34
Q

describe pathogenesis of TSS SUPERANTIGEN IN ppl who no dont have an antibody against TSST

A

Staph aures enter blood stream, causing toxemia BY REALEASING MASSIVE AMOUNT OF IL1 , TNF AND IL2–> BLOOD CULTURES WILL BE GEATIVE– IT IS THE SUPERANTIGEN CAUSING THE SYMPTOMS

35
Q

how does exfolatin cause scalded skin syndrome

A

epidermolytic- acts as a protease that cleaves desmoglein in desmosomes–> leads to separation of the dermis epidermis at the GRANULAR LAYER

36
Q

staph aureus has 2 exotoxins that can kill leukocytes (leukocidins) and can cause necorosis

A

Alpha toxin-necrosis and hemolysis (forms hols in cell membrane)
P-V leukocidin-pore forming toxin that kills cells, espcially WBCs

37
Q

significance of P-V leukocidin

A

two subunits of toxin–> form a pore in the cell wall
->severe skin and soft tissue infection in MRSA and severe necrotizing pneumonia

2% of Staph aureus isolates cary this lysogenic phage

38
Q

Staph epi and saprophyticus cause…

A

PYOGENIC INFECTIONS ONLY
no tss no exotoxins, no food poisoning
Epi- endocarditis and septic arthritis
Sap-cystitis and UTI

39
Q

disseminated sepsis and endocarditis associated with IVDU is most likely caused by

A

Staph aureus fom IVDU

not epi

40
Q

severe necrotizing and soft tissue infections with MRSA are caused by

A

community acquired strains that make the P-V leukocidin

*homeless an IVDU’s

41
Q

of hospital acquired Staph infections

A

50% of the time are MRSA

42
Q

right sided endocarditis in IV drug users–>

A

Staph Aureus

43
Q

prosthetic valve endocarditis

A

Staph epi

44
Q

most common cause of postsurgial wound infections

A

staph aureus

45
Q

osteomyeltis in chilren

A

staph aureus

46
Q

following a influenza URTI

A

Staph pneumonia and Pneumococcal pneumonia

  • staph pneumonia- severe and necrotizing can be CA or HA
  • empyema and abcesses
  • in SOME HOSPITALS IT IS THE LEADING CAUSE OF VAP, BUT WE LEARNED P AERUGINOSA AND ACINETOBACTER
47
Q

CONJUNCTIVITIS leading cause overall

tranfmitted from the eye by infected fingers

A

Staph aureus

48
Q

Conjunctivitis leading cause in children

transmitted to the eye from infected fingers

A

strep penumo

then h flu

49
Q

metastatic abcesses

A

occur via the spread of infection from the original site and can wind up in any organ (espcially the kidneys)

50
Q

definition of TSS

A

hypotension
diffuse macular rash–> transition to desquamative
involing 3 or more: liver, kidney, GI, CNS, muscle, or blood

51
Q

vasculitis involving small or medium blood vessels especially the coronary vasculature

A

KAWASAKI’S SYNDROMe

52
Q

Describe scalded skin syndrome

A

CHILDREN–> fever, large bullae, erythematous macular rash–> desquamaive transition–> serous fluid exudates, and electrolyte imbalance occurs, hair and nails lost
*uaually resolves in 7-10 days

53
Q

describe presentation of KS

A 
high fever for 5 days
bilateral non-purulent conjunctivitis
STRAWBERRY TONGUE-->lesions of the lips/tongue/oral mucosa
diffuse rash
edema of the hands and feet
leading TO HEART INVOLVEMENT
54
Q

HEART INVOLVEMENT WITH KS

A

ANEURYSM OF CORONARY ARTERIES

MYOCARDITIS, ARRHYTMIAS, REGURGITAITON OF MITRAL OR AORTIC VALVES

55
Q

WHO GETS KS

A

ASIAN KIDS UNDER 5–> MHC POLYMORPHISMS

56
Q

TX FOR KS

A

IVIG
FEVER REDUCERS
SUPPORTIVE CARE

57
Q

HOW TO DIFFERENTIATE STAPH EPI FROM SAPROPHITICUS

A

EPI-NOVOBIOCIN SENSITIVE

SAPROPHITICUS-NOVOBIOCIN RESISTANT

58
Q

GOLD COLONIES ON MANNITOL SALT AGAR WITH BETA HEMOLYSIS

A

STAPH AUREUS

59
Q

WHITE COLONIES ON MANNITOL-SALT AGAR WITH NO HEMOLYSIS

A

STAPH EPI

STAPH SAPROPHITICUS

60
Q

SEROLOGIC OR skin test for acute staph infection

A

none

61
Q

is a positive culture required for Dx of TSS

A

no

62
Q

90% of US staph strains are resitant to

A

penicillin G–> most having a beta lactamase

63
Q

tx for penicillin G staph strains

A

beta lactamase resistant penicillin (nafcillin, methicillin, cloxicillin)
some cephs
vancomycin
OR BETA LACTAMASE SENSITIVE PENICILLIN + BETA LACTAMSE INHIBITOR
(AUGMENTIN)

64
Q

according to Derm website tx of MRSA OR NRSA=

A
  1. clindamycin
  2. bactrim (TMP/SMX)
  3. DOXYCYCLIN
  4. LINEZOLID
  5. VANCOMYCIN
65
Q

20% OF STAPH STRAINS ARE…

A

METHICILLIN RESISTANT OR NAFCILLIN RESISTANT–> altered PBP’s

66
Q

LANGE SAYS MRSA or NRSA tx is

A

Life threatening:
vancomycin (+ gentamicin)
daptomycin (cubicin)–> non pneumonia

NON-life threatening:
Bactrim
clindamycin

67
Q

MRSA strains are resistant to almost all

A

beta lactam drugs including oenicllin and cephalosporins

68
Q

first beta lactam capable of treating MRSA

A

ceftaroline

69
Q

Tx of VISA an VRSA

also nafcillin and methicillin resistant too

A

daptomycin

quinipristin-dalfopristin

70
Q

tx of tss

A 
correction of shock with normal saline
pressor drugs (alpha 1 agonist)
intoropic agents
naficllin (beta lactamase resistant penicillin)
removal of tampon and debridement
pooled serum antibodies against TSST
71
Q

topical tx of STaph infections

A

murpirocin

also reduces nasal carriage

72
Q

cornerstone of abcess tx

A

drainage either surgical or spontaneous

73
Q

tx of faruncle (boil)

A

drainage–> no Ab’s required

74
Q

staph epi tx

A

highly resistant
most produce beta lactamases but are susceptible to Nafcillin (beta lactamse resistant penicillin)
Vanc is MRSE due to altered PBP’s

75
Q

tx of Staph saprophyticus

A

Bactrim or ciprofloxacin

Dermatology (12 decks)

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