Intro to infectious disease Flashcards

1
Q

Gram positive (structure)

A

cell wall Rigid, thick
Made up of mostly of peptidoglycan (50-60%)
A series of cross-linking (transpeptidases) help to create the building blocks of the cell wall.

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2
Q

Gram negative (structure)

A

multiple layered structure
Cell Wall Thin layer-one or two glycan chains
Cell wall protected by lipoprotein outer layer-which functions as penetration barrier.
lipopolysaccharide (LPS)
Matrix protein (porin)-important for regulating influx of molecules
phospholipids

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3
Q

Walls of mycobacteria (acid fast bacteria)

A

Contains peptidoglycan w/polysaccharide and glycolipids

Associated w/staining characteristics

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4
Q

Cytoplasmic membrane

A

Osmotic barrier
Energy production (electron transport-energy gradient-ATPases)
Biosynthesis transport (nutrient uptake, enzyme secretion)
Protein and lipid—lacks sterols

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5
Q

Minimum Inhibitory Concentration (MIC)

A

lowest concentration of antibiotic that inhibits visible growth of the bacteria. value used to indicate susceptible, intermediate and resistant

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6
Q

List of Gram Positive Cocci (Aerobic)

A

Staphylococcus aureus (coag+): Methicillin-sensitive (MSSA), Hospital or Community aquired MRSA
Staphylococcus epidemidis (coag -)
Staphylococcus saprophyticus (coag -)
Enterococcus faecalis
Enterococcus faecium
Enterococcus durans
β hemolytic: Streptococcus pyogenes (Grp A), Streptococcus agalactiae (Grp B,) Streptococcus bovis (nonenterococci, Grp D)
Viridans streptococci – α hemolytic: Streptococcus sangius, Streptococcus salivarius, Streptococcus mitis, Streptococcus mutans
Streptococcus pneumoniae (pneumococcus)

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7
Q

Staphylococci: colonization and infections caused

A

Colonization: Skin, Nose
Infections Caused: Cellulitis, wounds, trauma
Bacteremia/Endocarditis, Pneumonia,Osteomyelitis
UTI
Major players in post-surgical infections
Adhere to foreign material and catheters

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8
Q

Staphylococcal resistance

A

Penicillin Resistance: Beta-lactamase production, > 90% of all staphylococcus are resistant to penicillin
Methicillin Resistance: MecA gene codes for novel PBP2a, ~50% of S. aureus are resistant, ~70% of CoNS are resistant
Methicillin-susceptible isolates are also susceptible to cephalosporins and carbapenems

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9
Q

Streptococcus: Colonization

A

Skin: Group A- S. pyogenes
Mouth: Viridans Streptococcus, Anaerobes (e.g., peptostreptococcus)
Nasopharynx: Group A- S. pyogenes
Lower GI: Group D- S. bovis, Viridans, Streptococcus, Anaerobes
Female Genital Tract: Group B- S. agalactiae

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10
Q

Streptococcus: infections caused

A

Cellulitis: Group A- S. pyogenes, may result in Nec fasciitis
Dental carries: Viridans Streptococcus
Pharyngitis (Strep throat): Group A- S. pyogenes
Bacteremia/Endocarditis: Viridans Streptococcus
Neonatal meningitis: Group B- S. agalactiae

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11
Q

When establishing MIC, what is the difference between susceptible, intermediate, or resistant?

A

Susceptible- isolates may be appropriately treated with the recommended doses
Intermediate- isolates may be appropriately treated in body sites where the drug is physiologically concentrated or when a high dosage of drug can be used
Resistant- isolates are not inhibited by the achievable concentrations of a normal dose

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12
Q

WBC with differential: parameters

A
Neutrophils 50-70%
Lymphocytes 25-35%
Monocytes 2-6%
Eosinophils 0-6%
Basophils0-3%
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13
Q

granulocytes (B.E.N)

A

neutrophils, eosinophils, basophils

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14
Q

Neutrophils

A

Prevent microorganism invasion, kill invading organisms
Attracted to site of infection by chemotactic factors
Phagocytize microorganisms- eat up invading organism
Release toxic substances from granules within cell into vacuole containing organism

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15
Q

Absolute Neutrophil Count (ANC)

A

WBC # x (% segs (mature neutrophils)+ %bands (immature neutrophils)
The lower ANC= the higher risk for infection
Neutropenia defined based on ANC-
Mild = ANC 1000-1500/mm3
Moderate= ANC 500-1000/mm3
Severe= ANC < 500/mm3

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16
Q

Lymphocytes

A

Effector cells of immune system, recognize invaders, tag them for removal and kill them.
Make antibodies
T cells- 80%
B cells- 20%

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17
Q

Monocytes

A

precursors to macrophages

Serve to replenish tissues with macrophages prior to and during immune response

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18
Q

Eosinophils

A

Responsible for immune processes against helminths and parasites (also involved in allergic reaction)

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19
Q

Basophils

A

Mediate inflammatory response

20
Q

Gram+: Cocci (list)- Chains

A

CHAINS
Streptococcus pyrogens
Viridans Streptococcus

21
Q

Gram+: Cocci (list)-Pairs

A

PAIRS
Streptococcus pneumoniae
Enterococcus spp.

22
Q

Gram+: Cocci (list)-clusters

A

CLUSTERS
Coagulase-Positive Staphylococcus (S. aureus)
Coagulase-Negative Staphylococcus (S. epidermis)

23
Q

Gram+: Bacilli

A

Listeria

Lactobacillus

24
Q

Gram -: Cocci

A

COCCI
Neisseria menigitidis
Neisseria gonorrhoeae

25
Q

Gram -: Bacilli

A
Escherichia coli
Klebsiella spp.
Enterobacter spp.
Proteus spp.
Serratia marcescens
Pseudomonas spp.
26
Q

Gram -: coccobacilli

A

Haemophilus influenzae

27
Q

Pneumococci: Colonization

A

Oropharynx

Nasopharnyx

28
Q

Pneumococci: infections caused

A

Otitis media
Sinusitis
Bronchitis
Pneumonia (CAP- community acquired pneumonia)

29
Q

How do you treat Streptococcus

A

Penicillin

More resistance seen with α- hemolytic strep, specifically S. miti

30
Q

Concern for patients with Asplenia

A

Patients are at risk for fulminant sepsis syndrome
Lack filtration mechanism of spleen macrophages
Cannot clear encapsulated organisms (body requires spleen to clear the following bacteria)
S. pneumoniae
H. influenzae
N. menigitiis

31
Q

Treatment of Pneumococci

A

3rd generation cephalosporins (ceftriaxone)
May de-escalate with cultures and sensitivities
(Penicillin not a good choice d/t resistance)

32
Q

Enterococci: colonization

A

Gastrointestinal tract
Female genital tract
Very resistant- harder to kill than staph or strep

33
Q

Enterococci: infections

A

Opportunistic- takes over when you lose normal flora or when immune system is compromised.
Urinary tract infection
Bacteremia/Endocarditis
Intra-abdominal infections

34
Q

Gram negative (Aerobic) List

A
Rods: Enterobacteraciae: Enterobacter spp, Escherichia coli
Klebsiella pneumoniae
Proteus vulgaris, Proteus mirabilis
Serratia marcenena
Pseudomonas aeruginosa 

Cocci/coccobaccilli: Haemophilis influenzae, Nisseiria meningitiis

35
Q

Enterobacteraciae (gram -)

A

GI tract colonization
(Also: Soil,Water, Vegetation)

Gram negative have Lipopolysaccharide (LPS), Cell wall component
Acts as an Endotoxin

36
Q

Enterobacteraciae: infections

A

Urinary tract infections (accounts for 70%)
Intraabdominal infections
Bacteremia
Nosocomial pneumonia (pts in hospital, not out in community)
Diabetic foot infections

37
Q

Enterobacteraciae Resistance

A

Prevalent
More common in hospital-acquired infections
Treatment guided by in vitro susceptibility testing–cultures are essential

38
Q

Pseudomonas aeruginosa: colonization

A

Not considered normal flora (soil, water, vegetation)
Can colonize upper respiratory tract of immunocompromised patients
Cystic fibrosis
COPD

39
Q

Pseudomonas aeruginosa: infections

A

Opportunist: Immunocompromised patient
If pt has been on Broad spectrum antibiotics
Ventilation equipment-psudomonas clings to equipment (thats why you see it in cystic fibrosis a lot).

Nosocomial infections
Hospital acquired pneumonia (HAP)
Febrile neutropenia
Skin and soft tissue infections (burns, trauma, post-surgical)
Urinary tract infections (nursing home or hospital most likely)

40
Q

SPACE

A
Remembering when to double cover—treat these with 2 antibiotics:
Serratia
Pseudomonas
Acinetobacter
Citrobacter
Enterobacter
41
Q

Gram – Coccobacilli

A
Haemophilus influenzae
Encapsulated
More virulent
Not regular colonizer
Causes meningititis

No capsule
Colonizes upper resp tract
Causes ottitis media, sinusitis, CA

42
Q

Polysaccharide Capsule

A
Eludes immune system
Requires spleen for elimination
PS capsule is target for vaccine 
Hib vaccine
Meningococcal vaccine
43
Q

Anaerobes

A

Upper and lower GI tract, vaginal colonizers
Associated with intraabdominal infection, aspiration pneumonia, endometritis, PID, diabetic lower extremity infections, dental carries, head and neck
Above diaphragm
Peptostreptococcus spp. (gram + cocci)
Actinomyces spp (gram + rod)
Fusobacterium (gram – rod)

Below diaphragm
Bacteroides fragilis (gram – rod)
Lactobacillus (gram + rod)
Clostridium spp (gram + rod)

Gram-negative isolates are usually penicillinase producers

44
Q

Atypicals

A
Not normal colonizers
Not able to gram stain
Multiply intracellularly
Examples:
Mycoplasma pneumonia
Legionella pneumophilia
Chlamydophila pneumoniae

Can result in CAP (community acquired pnemonia)

45
Q

Even Some Super Killers Have Pretty Nice Capsules

A
Escherichia Coli
Streptococcus Pneumoniae
Salmonella
Klebsiella pneumoniae
Haemophilus influenzae
Pseudomonas aeruginosa
Neisseria meningitidis
Cryptococcus neoformans (yeast)
46
Q

Nine Important “Classes” of Bacterial Pathogens (1-5)

A

Streptococci- Group A strep, viridans strep
Streptococcus Pneumoniae
Enterococcus- usually faecalis
Staphylococci- S. aureus, coagulase-negative
Atypical bacteria- Mycoplasma, Chlamydia, Legionella

47
Q

Nine Important “Classes” of Bacterial Pathogens (6-9)

A

Haemophilus influenzae
Gram- negative rods- E.coli, Klebsiella, Proteus, etc.
Pseudomonas aeruginosa
Anaerobes- Bacteroides, Clostridia, Prevotella