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Infectous Disease > Dr. Cluck > Flashcards

Dr. Cluck Flashcards

(55 cards)

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1
Q

What is an infection?

A

A microorganism that is able to replicate invades host tissue and causes an immune response (disease)

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2
Q

Example of an infection

A

A gram-negative bacteria in a septic environment of the body –> in the blood stream

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3
Q

What is a Contaminant?

A

On the outside

Organism as a normal part of the skin flora, isolated from the bloodstream

-but there could be some bacteria as Contaminants in the bloodstream

-Almost never requires treatment

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4
Q

What is a Colonization?

A

An organism that is endemic to a specific part of the body

-MRSA colonization after being in the hospital
-Usually doesn’t require treatment

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5
Q

What are Gram-resistant Organisms?

A

-They need special forms of staining or cant be stained (lack of cell wall)

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6
Q

Why do Gram-resistants need special staining or cant be stained?

A

-Mycobacteria and Nocardia have a wax-like outer layer -> cant take up the stain -> acid-fast

-Treponema requires fluorescent AB staining
-Intracellular pathogens - cant be stained
-Mycoplasma lacks cell wall - cant be stained

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7
Q

What is an atypical organism?
EXAM

A

-Gram-resistant

-Neither Gram-positive nor Gram-negative

-bacteria that do not get colored by gram-staining but rather remain colorless

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8
Q

What are the most common morphological forms of bacteria?

A

-Rod-shaped: E. coli
-Cocci in chains: Streptococcus spp.
-Grapelike cluster: Staphylococcus spp.

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9
Q

How are Cocci-shaped gram (+) bacteria specified?

A

with Catalase
Clusters: Staphylococcus spp.

w/o Catalase
Pairs/chains: Streptococcus spp.

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10
Q

How is Staphylococcus specified?

A

(+) Coagulase: S. aureus -> causes disease

(-) Coagulase: S. epidermidis, S. saprophyticus

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11
Q

How is Streptococcus specified?

A

-alpha hemolysis: partial, green
-beta hemolysis: complete, clear
-gamma hemolysis: no hemolysis

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12
Q

How are rods specified:

A

Aerobic and Anaerobic

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13
Q

Assays to identify Gram (+):

A

Gram staining (cluster VS strips)
Biochemical: Catalase, Coagulase
Lancefield antigens (carbohydrate side chain)
Hemolytic reaction on blood agar

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14
Q

Why should Staph aureus NEVER be considered Contaminant?

A

-most virulent gram-positive pathogen
-can cause multiple diseases: bacteremia, skin tissue infections, endocarditis, pneumonia, foodborne, toxic shock

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15
Q

Characteristics of Staph. aureus

A

-produces ß-lactamases
-Catalase and Coagulase positive (only coagulase pos. staph.)
-Methicilin-resistance through mecA gene (PBP2a protein)

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16
Q

Function of Catalase

Function of Coagulase

A

Catalase: reduces phagocytic killing

Coagulase: facilitates abscess formation

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17
Q

How does Penicillin work?

A

-It inhibits the Transpeptidase in the cell wall of bacteria

-mecA creates PBP2a -> the cell wall is able to continue its replication

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18
Q

What is the therapeutical approach to Staph aureus?

A

Vancomycin
If Severe -> IV therapy
If MSSA -> antistaphylococcal penicillin C D M N O (penicillinase-resistant penicillin) or 1st gen cephalosporin
PO: dicloxacillin, cephalexin (1st gen cephalosporin)

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19
Q

Why do penicillinase-resistant penicillins work against bacteria with ß-lactamase?

A

Because of the bulky sidechain (steric hindrance), bacterias ß-lactamase cant access the ß-lactam ring and hydrolyze it

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20
Q

Which antibiotic doesn’t work for MSSA?

A

Vancomycin ????
-studies show poor outcome

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21
Q

EXAM Question: Know which antibiotics are IV and which are PO

A

If severe -> IV: Nafcillin

Cephalexin (PO) would be the best choice

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22
Q

What are therapeutic options to treat MRSA?

A

If invasive (f.e. Pneumonia), not superficial -> Vancomycin

If superficial -> PO: doxycyclin, clindamycin, TMP-SMX

Alternatives: linezolid, daptomycin, tigecycline, ceftaroline

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23
Q

What is the difference between Staph aureus and epidermidis

Study These Flashcards
A

Staph epidermidis is Coagulase negative

often considered contaminant, but still cause disease -> often on prosthetic devices (pacemakers) -> because they are sticky and build biofilms

24
Q

How to treat Staph epidermidis?

Study These Flashcards
A

If there is an infection Vancomycin is necessary
due to mecA and methicillin-resistance

25
How are staph. saprophyticus different from other spp?
-dont produce ß-lactamase -> can be treated with ß-lactams, TMP-SMX or fluoroquinolone -mostly cause UTI in young sexually active females
26
What are Lancefield Antigens?
-antigenic differences in cell wall carbohydrates of Streptococcus spp. -Gr. A, B, D Possible Examq: Which Strep doesn't have Lancefield Antigen -> Streptococcus pneumoniae?
27
Hemolytic reactions
Alpha: partial, green Beta: complete, clear Gamma: no hemolysis
28
What else makes Streptococcus spp. different from Staphylococcus?
-they DO NOT produce b-lactamase -> Amoxicillin/Clavulanate (Augmentin) won't work ???(adverse effect: diarrhea) -> use Penicillin
29
How to treat Streptococcus pyogenes?
Penicillin; if PCN allergic -> Clindamycin or TMP-SMX
30
Streptococcus agalactiae - Group B strep
-often found with wound infections in diabetics, obese patients -neonatal infection (meningitis) - colonizer of the vagina --> take Penicillin to decolonize -normal inhabitant of the GI
31
What is the susceptibility of Group A and B strep to Penicillin?
100% any ß-lactam can be used (one exception)
32
What is S. gallolyticus (bovis) known for?
-Group D Strep --> treat with Penicillin -Normal inhabitant of the GI -when found in the blood -> marker for colonic neoplasia -can cause endocarditis
33
What does Streptococcus pneumoniae cause?
-Triad of endocarditis, meningitis, and pneumonia -30% PCN resistance -> different ß-lactam or FQ (fluoroquinolone)
34
Viridans streptococci + Streptococcus anginosus
-part of the normal GI flora (including oral cavity) -endocarditis secondary to poor dentition or damaged heart valves -Penicillin, resistance is rising
35
What is Enterococcus known for?
-normal bowel flora -not very pathogenic (BYSTANDER analogy), unless it is found where it is not supposed to be (blood) -very resistant -can cause wound infections, endocarditis, UTI
36
Name two important Enterococci
-E. faecalis - responds better to drugs -E. faecium is more drug resistant
37
How to treat Enterococcus?
-Use two drugs - the concept of drug SYNERGY (2 different MOAs) -one ß-lactam is just bacteriostatic -1st line for E. faecalis line is Amino penicillins plus an aminoglycoside -for E. faecium (more resistant) -> Vancomycin -Alternative: Linezolid, daptomycin
38
Diseases caused by Mycobacteria
-wide range of diseases - Tuberculosis, leprosy
39
Identification and treatment of Mycobacteria
-lipid-rich cell wall -> acid-fast -differentiated by the rate of growth tuberculosis requires 4 drug therapy (1 year or longer) -Non-tuberculosis mycobacteria -> most are resistant: M. abscessus, M. fortuitum, M. marinum
40
Disease caused by Bacillus anthracis
Anthrax -B. cereus in reheated rice -antibiotics is not necessary
41
Listeria monocytogenes
-can cause meningitis, but often mild -food-borne illness -treat with ampicillin or TMP-SMX or Vancomycin -Neprosporin wont work!
42
Diseases caused by Clostridium
-C. perfringens can cause food-borne illness as well as gas gangrene -C. difficile is responsible for pseudomembranous colitis -C. tetani and C. botulinum cause different types of paralysis
43
How to treat Clostridium
-Almost all Clostridia spp. are penicillin-susceptible -C. difficile - oral Vancomycin; in severe case add IV metronidazole
44
What is the only organism that is treated with oral Vancomycin?
Clostridium difficile
45
Bacteria causing infection the upper respiratory tract
-Moraxella catarrhalis -> CA-pneumonia, otitis media, and sinusitis -Haemophilus influenzae (type B capsule) - vaccine available
46
Acinetobacter sbb.
-Very resistant pathogen (hospital outbreaks) -VAP and wound infections -sulbactam has microbiologic activity (ß-lactam inhibitor usually don't have activity)
47
Neisseria
* N. meningitidis is responsible for meningitis -> 3rd generation cephalosporin/Pen G * N. gonorrhoeae is responsible for gonorrhea, septic arthritis, and PID -> cephalosporins Alternative: FQ, macrolides
48
What are Enterics?
-Enterobacterales (big class) -commonly seen in hospital-acquired syndromes and immunocompromised patients -Salmonella and Shigella are NOT part of normal flora
49
What are the Resistance Patterns Associated with Enterobacterales?
-E.coli and Klebsiella can produce extended spectrum β-lactamases (ESBLs) AmpC-ß-lactamase hydrolyze many ß-lactams -use carbapeneme to treat
50
Pseudomonas aeruginosa
-significant in hospital-acquired infections -often multidrug-resistant
51
Characteristics of Anaerobes
-a harmless commensal relationship with the host -Trauma and host factors can cause infection -treat -> agents with activity against anaerobes (eg metronidazole, clindamycin, carbapenems)
52
Use of carbapenems:
-against anaerobes -Enterobacterels with resistance pattern -> E. coli and Klebsiella
53
Rocky Mountain Spotted Fever
Rickettsia rickettsii -gram-negative intracellular coccobacillus -transmission via arthropods (ticks) -treat with Doxycycline 100 mg BID in pregnancy chloramphenicol
54
Lyme Disease
-Borrelia burgdorferi (intracellular) -Transmission also occurs via an arthropod vector – ticks -Treatment is doxycycline or a β-lactam (usually ß-lactams don't work for intracellular pathogens)
55
Chlamydophila vs.Chlamydia
-Chlamydophila pneumoniae: atypical pneumonia -> Community acquired -> Doxycyline -Chlamydia trachomatis: STD -> Doxycycline -need high intracellular concentrations such as macrolides or tetracyclines

Infectous Disease (29 decks)

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