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🧪 Culture & Sensitivity – Blood (Aerobic + Anaerobic)

Test Name	Blood Culture & Sensitivity (Aerobic & Anaerobic)
Sample Type	Whole Blood (2 bottles: 1 Aerobic, 1 Anaerobic)
Fasting Required	❌ Not required
Collection Note	Strict aseptic technique; preferably before starting antibiotics
Turnaround Time	Preliminary: 24–48 hours, Final: 5–7 days
Volume Required	Adults: 8–10 mL per bottle; Pediatrics: 1–5 mL
Department	Microbiology / Infectious Diseases

🧬 What is this Test?

Blood culture and sensitivity testing involves:

Culturing blood to detect bacteria or fungi in the bloodstream.
Identifying the organism(s) (aerobic or anaerobic).
Performing antibiotic susceptibility testing (sensitivity) to determine effective treatment.

🧫 Why Two Bottles – Aerobic & Anaerobic?

Bottle Type	Purpose
Aerobic	Detects organisms that require oxygen (e.g., E. coli, Staph, Klebsiella)
Anaerobic	Detects organisms that grow without oxygen (e.g., Bacteroides, Clostridium)

This dual approach increases the detection rate for bloodstream infections.

🩺 Why is it Done?

Clinical Scenario	Purpose
Suspected sepsis or septicemia	Identify bloodstream infection
Fever of unknown origin (FUO)	Rule out systemic bacterial/fungal infections
Monitoring infective endocarditis	Confirm continuous bacteremia
Immunocompromised patient with fever	Detect opportunistic pathogens
Prior to long-term antibiotic therapy	Ensure infection is present and guide treatment

🧪 Interpretation

Result	Meaning
✅ No growth after 5–7 days	No detectable bacteria/fungi in blood
⚠️ Positive growth	Indicates bacteremia or fungemia; requires organism identification and sensitivity testing
❗ Contaminants	Skin flora like coagulase-negative Staphylococci may indicate poor collection technique (interpret cautiously)

💊 What is "Sensitivity" Testing?

Also known as Antibiotic Susceptibility Testing (AST):

Identifies which antibiotics the bacteria are sensitive (S), resistant (R), or intermediate (I) to.
Helps in selecting the most effective, targeted therapy, avoiding broad-spectrum overuse.

⚠️ Important Pre-Testing Notes

Before Collection	Rationale
✅ Collect before starting antibiotics	Antibiotics can suppress growth, giving false negatives
✅ Use aseptic technique	To avoid contamination with skin flora
✅ Repeat cultures if needed	Two or more sets from different sites improve accuracy

🧪 Other Tests Commonly Ordered Together

Test	Purpose
CBC	Detect leukocytosis, infection markers
CRP / Procalcitonin	Track systemic inflammation and bacterial activity
Lactate	Monitor for sepsis
Urine or sputum cultures	Identify primary source of infection
Chest X-ray / USG / CT	Identify underlying abscess, pneumonia, etc.

🧠 Summary Table

Feature	Details
Sample	2 blood bottles: 1 aerobic, 1 anaerobic
Detects	Bacterial/fungal bloodstream infection
Indicates	Sepsis, endocarditis, FUO, etc.
Guides	Antibiotic choice via sensitivity testing
Best Done Before	Starting antibiotics

Culture & Sensitivity, Aerobic bacteria Blood 1 Aerobic,1-Anerobic