AMBLER CIS - SRS

Question 1

What are the three mechanisms of antibiotic resistance we covered?

Answer 1

1. Decreased penetration to target
2. Alteration of target site
3. Inactivation by enzyme

Question 2

What is an example of how organisms alter antibiotic target sites?

Answer 2

•change in PBP by strep and staph so it is not recognized

Question 3

What are some examples of inactivation of antibiotics by bacterial enzyme?

Answer 3

•enzyme eats abx renderning ineffective. ‘ase’. ie penicillinase, carbapenimase

Question 4

How are Antibiotic resistance characteristics transferred?

Answer 4

a. chromosomal - ie inducible by Enterobacter
b. plasmid – can be a moving target as non chromosomal
c. transposon – non chromosomal like plasmid. ‘jumping genes’

Question 5

What are five types of beta-lactam resistances we encounter?

Answer 5

1. •Penicillinase
2. •Cephalosporinase
3. •ESBL (Extended Spectrim Beta-lactamase)
4. •AMP-C
5. •Carbapenemase. ‘CRE’ has been in the news a lot recently.

Question 6

What are the tests shown here?

What are they for?

Answer 6

•Kirby Bauer
–abx discs and read zone of clearing; CLSI has breakpoints for S, I or R
•e-Test
–graduated concentration of abx and read point

Question 7

What does leukocyte esterase detect?

What is it diagnostic for?

Answer 7

–Leukocyte esterase great at detecting very small WBC’s so despite decent sens/spec:75-96%/94-98%,

it is not diagnostic and does not inform how many white cells present.

Question 8

What are the ways we identify (attempt to anyway) UTI?

Answer 8

–1) symptoms.
–2) pyuria (increase in wbc’s)
–3) bacteria suggestive of infection. ie Staph epi = no.

Question 9

What are the 7 clinical pearls related to blood culturing that we were given?

Answer 9

1. –always try 2 separate sites of draw
2. –if rigors/chills. Get 2 sets stat as rigors signify clearing of the bacteremia
3. –if fever then q 15 min is fine
4. –if thinking endocarditis or persistant bacteremia, showing persistence over time necessary.
5. –Newer blood culture machines are better at culturing the ‘fastidious- (ie HACEK group).
6. –Not many instances for holding blood cultures >5 days. Propionibacterium is one common exception
7. –Fungal blood cultures very low yield except candida which grows on normal culture stuff.

Question 10

What is BSA agar? What is it good for?

Answer 10

Blood sheep agar

•routine. most things GP, GN and candida grow here

Question 11

What organisms do we use MacConkey agar for?

Answer 11

•For Gram negatives/enterics (bile tolerant).

Question 12

Name this agar, and tell us what it is made of/used for!

Answer 12

–Chocolate
•lysed red cell media to release nutrients for picky (fastidious) organisms

Question 13

What do you suppose this agar is?

What is it for?

Answer 13

–Sabouraud
•for dermatophytes and other fungi

Question 14

What is a key component in obtaining a sputum specimin?

Answer 14

Must attempt to avoid oral contamination as the sample is removed. This is difficult due to the high load of organisms (particularly anaerobics).

Question 15

It is thought that a minimum of how many organisms must be present for a gram stain procedure to work?

What does this mean for us?

Answer 15

10^4 to 10^5 organisms.

Means that staining a simple sputum specimen may be insufficient, and you may have to wait for culture growth.

Question 16

See if you can rattle off 8 encapsulated bacteria.

Answer 16

1. •Typeable Haemophilus influenzae (ie type B)
2. •Strep pneumo
3. •Neisseria meningiditis
4. •Strep agalactiae (group B)
5. •Klebsiella
6. •Salmonella
7. •Capnocytophaga
8. •Crytptococcus

Question 17

Who are encapsulated organisms particularly bad for?

Answer 17

Asplenic patients

Question 18

In order from most to least common, what are the top three organisms that cause 85% of bacterial cases of community aquired pneumonia?

Answer 18

–Strep pneumoniae
–Haemophilus influenzae
–Moraxella catarrhalis

Question 19

What agar is best for growing H. influenza?

Answer 19

Chocolate, since this organism needs factors “V” and “X”.

Question 20

H. influenza type B and non-typable strains have capsules. Who are these infections common in?

Answer 20

–common in smoker/copd patients

Question 21

The arrow is indicating the patient’s enlarged epiglottis. The patient presents with fever, sore throat, and is leaning forward with their mouth open and drooling.

What is the infection?

What must you be aware of in this situation?

What is the best approach to managing this infection?

Answer 21

H. influenza type B

In kids especially life threatening since the can lose their airway rapidly due to the epiglottitis

As usual the best approach is prevention, vaccinations are available against this.

Question 22

Mycoplasma pneumoniae is a cause of what kind of pneumonia?

Answer 22

Atypical, “walking pneumonia”

Question 23

What is a somewhat unique way of testing for M. pneumoniae?

Answer 23

Cold agglutinins

Question 24

What are some of the extrapulmonary consequences of an M. pneumoniae infection?

Answer 24

–Hemolysis, usually mild
–skin: maculopapular rash or vesicular to SJS.
–CNS: 0.1% of all pts and 7% hospitalized pts. aseptic menigitis, peripheral neuropathy, cranial nerve palsy, cerebellar ataxia, ADEM and transverse myelitis
–cardiac: one of the more common presentations with rhythm abnormality, CHF
–Rheum: raynauds, polyarthralgias and mylagias from immune-medicated mechanism but has been cultured from synovial fluid.
–rare Glomeruloneprhitis
–rare hepatitis and pancreatitis
–Otitis media and bullous myrigitis

Question 25

*Legionella pneumophila* is another atypical pneumonia. What are 8 common presentations associated with this?

Answer 25

1. syndrome of fever with temp/HR dissociation, 2. Head ache 3. , myalgia, 4. confusion, 5. diarrhea, 6. cough, 7. inc LFT’s. 8. Hyponatremia

Question 26

What is *Legionella pneumophila* resistant to?

Answer 26

Cephalosporins

Question 27

What are the most common causative agents of endocarditis, and what type are they involved in?

Answer 27

1. *Streptococcus viridans:* Sub acute endocarditis 2. *Staphylococcus aureus:* Acute endocarditis 3. *S. Epidermidis:* foreing body

Question 28

The HACEK group is associated with endocarditis. What are the organisms of the HACEK group?

Answer 28

–**H**aemophilus aphrophilus –**A**ctinobacillus actinomycetemcomitans –**C**ardiobacterium hominis –**E**ikenella corrodens –**K**ingella kingae

Question 29

How does one get *Eikenella corrodens*?

Answer 29

Human bites

Question 30

Neutropenic fever is particularly concerning d/t the lack of an intact immune system. Describe the management of a patient like this.

Answer 30

1. Obtain cultures including blood, sputum if able, urine. 2. start empiric anti-pseudomonal abx 3. begin Gram positive coverage if line suggested as possible source. (cover MRSA/MRSE) 4. obtain imaging as needed 5. if after 4-7 days with fever, without source, add antifungal

Question 31

What are the diagnostic criteria for a "fever of unknown origin"

Answer 31

Outpatient -Three weeks fever without diagnosis Inpatient - Three days fever without diagnosis

Question 32

See if you can articulate the minimum workup for a FOUO.

Answer 32

–blood cultures, erythrocyte sedimentation rate or C-reactive protein, serum lactate dehydrogenase, HIV antibody test and viral load, rheumatoid factor, heterophile antibody test, creatine phosphokinase, antinuclear antibodies, tuberculin skin test or interferon-gamma release assay, serum protein electrophoresis, and computed tomography scan of abdomen and chest, LP, Bone marrow biopsy.

Question 33

What organism is associated with cat and to a lesser degree dog bites. That is also a small GNCB?

Answer 33

*Pasteurella multocida*

Question 34

What does *pasteurella multocida* produce that impacts antimicrobials? What does it lead to sometimes?

Answer 34

Beta-lactamase producer Tenosynovitis as well as joint and bone infections

Question 35

What is the causative agent of "cat scratch disease"?

Answer 35

*Bartonella henselae*

Question 36

What is *bartonella henselae* easily be mistaken for?

Answer 36

Often occurs in children as they tend to get scratched by cats more frequently... 1-3 weeks later the child will have enlarged, tender lymph nodes. This can freak out parents, and will make them think their child has lymphoma

Question 37

In aids, what does *bartonella henselae* cause?

Answer 37

Bacillary Angiomatosis

Question 38

In aids patients *B. henselae* can cause bacillary angiomatosis which can be a few to hundreds of lesions which are papules or nodules that are red, globular, and non-blanching with a vascular appearance. There can also be purplish nodules that are similar to what other common thing seen in AIDs patients?

Answer 38

Kaposi's sarcoma

Question 39

Which is more numerous in the GI tract? Aerobes or anaerobes?

Answer 39

Anaerobes, 1000:1

Question 40

What is the largest bacterial group in the GI tract?

Answer 40

*Bacteriodes fragilis*

Question 41

What are the two special conditions of anaerobic infections?

Answer 41

Ludwigs angina Lemiere's Syndrome

Question 42

What leads to Ludwigs angina? What is it?

Answer 42

* starts with dental infection 50-90% of the time * infection of sublingual and submandibular spaces especially with base of tongue swelling

Question 43

What organism causes Lemiere's syndrome?

Answer 43

•Fusobacterium necrophorum

Question 44

What is Lemiere's syndrome?

Answer 44

•post compartment of lateral pharyngeal space with suppurative thrombophlebitis of IJ vein. shows right sided septic emboli to lung (septic emboli due to infectious origin of embolus)