T3

Question 1

Normal skin flora contaminating blood culture

Answer 1

S. aureus, some fungi, Staph.

Question 2

We use one bottled blood sample for aerobic and anaerobic testing (T/F)

Answer 2

False; 2 bottles for aerobic, 2 for anerobic

Question 3

When we process the 2, bottle a grew staph aereus, bottle b grew e coli. Is this unusual?

Answer 3

Yes, bottles should show similar results. Contaminant present.

Question 4

Blood culture bottles

Answer 4

Blue - clotting factors
Purple - entire blood sample
Red - serum
Yellow -

Question 5

Maintaining asepsis - sample

Answer 5

• Sterile materials
• Chemicals to disinfect skin (0.5% chlorhexidine in 75% alcohol for adults no alcohol for kids)
• Apply with cotton in circular motions
• Needle exposure to air - already contaminated

Question 6

Staphylococci vs Streptococci

Answer 6

Staph

• Grape-like clusters
• Catalase Positive
• Coagulase positive
• Found on skin

Strep

• A chain of round cells
• Catalase -ve
• Coagulase -ve
• Found in respiratory tract

Question 7

Significance of blood culture isolate

Answer 7

Want to ensure that the m.o. is a true pathogen and not contaminant. If contaminant then wasting time and not helping cause of patient.
Can differentiate diff types of m.o. e.g. types of staph to determine treatment

Question 8

Causes of pneumonia

Answer 8

staph epiderdidimis, lungdidis, staph hemolyticus

Question 9

Distinguishing factor between staph and strep spp

Answer 9

Hemolysin -
Strep
-Either alpha, or beta or gamma hemolysis
Alpha hemolysis - strep pneumoniae 
Beta- strep pyrogenes 

Staph
-No hemolysis or beta hemolysis.

Question 10

Staphylococcus epididimis

Answer 10

Coagulase +ve
Catalase +ve
Staph epididimis causes pneumonia hence sol’n

Question 11

Determining clinical significance of treatment

Answer 11

Check parameters mentioned:
Symptoms and signs persistent,
Parameters of lab results
Ensure blood sample sent to lab wasn’t contaminated (by making sure to not start patient on antibiotics before blood culture, making sure blood sample was from appropriate site e.g. from line is not appropriate, another site of body is appropriate. Don’t take blood from hand with IV drip).
If patient still isn’t well, repeat blood culture.

Question 12

Clinical impact of previous blood culture isolate (contaminant)

Answer 12

• Need to treat completely then clear patient, > time of stay and money
• Allergy to antibiotic, additional cost meds
• MRSA - difficult to treat, could have gotten from another patient (staph aereus becomes difficult to treat) - due to long stay
• C deficile - if patient becomes susceptible to more infection
• Additional testing, administer antibiotics (too many antibiotics can cause potential resistance), cost (confirmation blood cultures expensive)
• Change of flora environment if treating contaminants

Question 13

Preventing effects of contaminant blood culture isolate

Answer 13

• method of taking blood sample, method of culture in lab, diff test methods must be very appropriate
• E test, automated system - antimicrobial testing methods to confirm
• Mec A gene in staph aereus for MRSA (Methicillin-resistant Staphylococcus aureus) - can isolate it to confirm – Difficult to treat with normal antibiotics, would save money to determine type of Staph
• Van A,B,C genes mediate resistance
  VanA alters the peptide target that vancomycin and closely related antibiotics (e.g., teicoplanin) normally bind to in order to inhibit bacterial cell wall synthesis.
  These Van genes are resistant to certain antibiotics, if hospital treated infection with these antibiotics, would prove useless, testing can save money, time and complications.