Improving Blood Culture Sensitivity WHEN AND WHY Blood ...
Improving Blood Culture Sensitivity WHEN AND WHY Blood ...
Improving Blood Culture Sensitivity WHEN AND WHY Blood ...
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Growth Possibilities Subculture to<br />
Tiny Gram<br />
Neg. Bacilli<br />
Haemophilus<br />
Brucella<br />
Anaerobic Gram<br />
Neg. Rod<br />
Choc Agar (CO 2 )<br />
Anaerobic Agar<br />
Direct Latex<br />
Direct Latex Technique<br />
(Mallow, et al., ICAAC 1987 ABST. #206<br />
• Centrifuge blood culture fluid at low speed<br />
to sediment RBC’s.<br />
• Heat at 100°C for 10 minutes in 3 volumes<br />
of EDTA to destroy interfering factors.<br />
• Clarify by centrifugation and test<br />
supernatant for antigen of bacteria seen<br />
on blood culture fluid gram stain.<br />
Growth Possibilities Subculture to<br />
Gram Positive Cocci<br />
(pairs or in chains)<br />
Strep. Pneumoniae<br />
Strep. Bovis<br />
Beta Strep<br />
Strep. Viridans<br />
Anaerobic Strep<br />
Others<br />
Direct Latex<br />
BAP w/Optochin &<br />
Bacitracin Disks<br />
Bile Esculin Slant<br />
Anaerobic Agar<br />
Gram Pos. Cocci<br />
(in chains or pairs)<br />
• Bile esculin positive, PYR positive Enterococcus<br />
GU tract, endocarditis requires gentamicin plus<br />
ampicillin or vancomycin.<br />
• Bile esculin positive, PYR negative possible<br />
Strep. Bovis. Endocarditis, CA of colon. No<br />
resistance to penicillin, cephalosporin.<br />
• Bile esculin negative – Other penicillin and<br />
cephalosporin sensitive streptococcus.<br />
After Hours Communication of<br />
Positives<br />
• Gram-negative rods are rarely contaminants, and<br />
there is high mortality due to shock and bleeding.<br />
• Laboratory contacts attending nurse, who<br />
immediately contacts the physician, regardless of<br />
time of day or night.<br />
• Gram-positive cocci and other bacteria are<br />
occasionally contaminants. Most antibiotics kill grampositive<br />
cocci.<br />
• Laboratory contacts nurse, who calls physician only if<br />
patient appears septic (e.g., fever and/or shock) and<br />
is not on an antibiotic. Physician not contacted after<br />
hours if patient is stable and on an antibiotic.<br />
<strong>Blood</strong> <strong>Culture</strong> Methods<br />
•Isolator<br />
• Instrument methods<br />
• Conventional bottles<br />
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