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Culture & Sensitivity, Aerobic bacteria CSF( Vitek 2 Compact)
Bacterial/ Viral
Report in 72Hrs
At Home
No Fasting Required
Details
Identifies bacteria & antibiotic susceptibility.
₹1,036₹1,480
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Culture & Sensitivity Aerobic bacteria CSF (Vitek 2 Compact)
- Why is it done?
- Identifies aerobic bacterial pathogens in cerebrospinal fluid (CSF) samples obtained through lumbar puncture or other invasive procedures
- Diagnoses bacterial meningitis, encephalitis, and other CNS infections in patients presenting with fever, altered mental status, neck stiffness, and headache
- Determines antibiotic susceptibility patterns to guide targeted antimicrobial therapy and prevent empiric overtreatment
- Monitors treatment efficacy in patients with documented bacterial CNS infections
- Performed urgently when meningitis is suspected, typically within hours of hospitalization as bacterial CNS infections are medical emergencies requiring immediate intervention
- Used as adjunct to gram stain microscopy for confirmation and definitive organism identification
- Normal Range
- Normal/Negative Result: No growth of aerobic bacteria after 24-48 hours of incubation
- Units of Measurement: Colony-forming units per milliliter (CFU/mL) or qualitative presence/absence
- Negative CSF Culture: Indicates absence of aerobic bacterial infection; patient likely has viral meningitis, aseptic meningitis, or non-infectious etiology
- Positive CSF Culture: Growth of pathogenic aerobic bacteria (any growth is typically considered clinically significant given the sterile nature of CSF compartment); organism identification and susceptibility results reported
- Borderline/Contamination: Growth of skin commensals (Coagulase-negative Staphylococcus, Corynebacterium, Bacillus) may represent contamination; clinical correlation required to distinguish from true infection
- Interpretation
- Positive Culture Results:
- Confirms bacterial meningitis or other acute bacterial CNS infection requiring immediate antimicrobial intervention
- Common aerobic pathogens identified include: Neisseria meningitidis, Streptococcus pneumoniae, Listeria monocytogenes, Gram-negative rods (E. coli, Klebsiella, Pseudomonas aeruginosa), Haemophilus influenzae
- Susceptibility testing results indicate which antibiotics are effective; reported as susceptible, intermediate, or resistant categories
- Vitek 2 Compact provides rapid identification through automated biochemical analysis and antibiotic susceptibility profiling, typically within 18-24 hours
- Negative Culture Results:
- Excludes bacterial etiology; however, does not rule out bacterial infection if obtained after antibiotic administration
- Suggests viral meningitis, aseptic meningitis, fungal infection, tuberculosis, or non-infectious inflammatory conditions; must correlate with CSF cell counts, protein, glucose, and clinical presentation
- Factors Affecting Results:
- Prior antibiotic administration decreases culture sensitivity; ideally obtain CSF before antibiotics or acknowledge timing in clinical interpretation
- Specimen contamination during collection or processing may result in false positives from skin flora
- Delayed transport or improper storage may reduce organism viability and culture sensitivity
- Low bacterial burden in early infection or partially treated meningitis may result in negative cultures despite active bacterial disease
- Fastidious organisms or those with special growth requirements may require extended incubation or special media not routinely used
- Associated Organs
- Primary Organ Systems:
- Central Nervous System (CNS): Brain and spinal cord; specifically evaluates meninges inflammation and parenchymal infection
- Peripheral Immune System: Response to CNS infection affects systemic immune activation and inflammatory markers
- Conditions Associated with Abnormal Results:
- Acute Bacterial Meningitis: Life-threatening infection of meningeal membranes; medical emergency with high mortality and morbidity if untreated
- Bacterial Encephalitis: Direct bacterial invasion of brain parenchyma causing altered mental status, seizures, and neurological complications
- Ventriculitis: Bacterial infection of ventricular system; often associated with shunts, drains, or post-neurosurgical procedures
- Subdural Empyema: Bacterial collection between dura and arachnoid; requires urgent surgical intervention
- Post-Neurosurgical Infection: Bacterial contamination following craniotomy, shunt placement, or invasive neurological procedures
- Immunocompromised Patients: Higher susceptibility to atypical or opportunistic bacterial pathogens
- Potential Complications of Untreated Bacterial CNS Infection:
- Permanent neurological sequelae: Hearing loss, cognitive impairment, motor deficits, seizures
- Hydrocephalus: Impaired CSF flow requiring ventriculoperitoneal shunt placement
- Sepsis and septic shock: Progression to systemic infection with multiorgan failure
- Death: Mortality rates 15-25% for meningococcal meningitis and 20-30% for pneumococcal meningitis if untreated
- Follow-up Tests
- Recommended Follow-up Based on Positive Culture:
- Repeat CSF Culture: Typically performed 24-48 hours after initiation of antibiotics to document sterilization and treatment efficacy; may be repeated if clinical deterioration occurs
- Blood Cultures: Obtained simultaneously with CSF; may identify same organism supporting diagnosis and assessing bacteremia severity
- CSF Cell Count and Differential: Determines inflammatory profile; lymphocytic vs neutrophilic predominance guides diagnostic consideration
- CSF Chemistry: Glucose and protein levels corroborate bacterial infection diagnosis; low glucose with elevated protein characteristic of bacterial meningitis
- CSF Gram Stain: Rapid presumptive organism identification; guides initial empiric therapy while awaiting culture results
- PCR Molecular Testing: Rapid detection of common meningitis pathogens (meningococcus, pneumococcus, H. influenzae) if available; supplements culture
- Associated Imaging and Diagnostic Studies:
- Brain MRI: Evaluates for complications including subdural empyema, ventriculitis, abscess formation, or cerebritis
- Head CT: Initial imaging to exclude contraindications to lumbar puncture or identify mass effect and increased intracranial pressure
- Laboratory Monitoring:
- Complete Blood Count: Assess for leukocytosis or leukopenia indicating severity of systemic response
- Procalcitonin and C-Reactive Protein: Measure inflammatory response and monitor treatment response; trending decreases indicate clinical improvement
- Blood Chemistry: Electrolytes, renal function, liver function to assess complications and drug toxicity from prolonged antibiotic therapy
- Audiometry: Recommended follow-up 2-4 weeks post-infection to detect sensorineural hearing loss from meningitis
- Monitoring Frequency:
- Clinical assessment every 6-12 hours during acute phase with documented meningitis
- Repeat CSF studies at 24-48 hours for positive initial culture to confirm sterilization
- Long-term neurological follow-up at 1 month and 3 months post-discharge to assess for sequelae
- Fasting Required?
- Fasting Required: No
- CSF cultures are obtained by lumbar puncture and are not affected by fasting status; no dietary restrictions necessary
- Patient Preparation Requirements:
- Informed Consent: Obtain consent for lumbar puncture procedure including explanation of risks (headache, infection, bleeding, neurological complications)
- Contraindication Assessment: Evaluate for mass lesions, papilledema, coagulopathy, or platelet dysfunction before lumbar puncture
- Positioning: Patient positioned in lateral decubitus position (side-lying) with knees flexed to chest or seated with chest flexed forward
- Bladder Emptying: Patient should void before procedure for comfort and accuracy of opening CSF pressure measurement
- Medications:
- Anticoagulants and Antiplatelet Agents: Ideally discontinued or held before lumbar puncture to reduce bleeding risk; coordinate timing with clinical urgency
- Sedatives/Anesthetics: May be administered for patient comfort; local anesthesia at puncture site standard
- Antibiotics: In meningitis suspected patients, initiate empiric antibiotics before or concurrent with lumbar puncture; do not delay therapy for culture
- Specimen Collection and Handling:
- Sterile Technique: Strict aseptic technique mandatory; use sterile needles and collection tubes; decontaminate skin with chlorhexidine or iodine-based antiseptic
- Tube Collection: Typically collect 3 mL CSF in sterile, sterile tube (usually tube #3 or final tube) for culture to minimize contamination
- Immediate Transport: Transport specimen to microbiology laboratory immediately; do not refrigerate; maintain room temperature to preserve organism viability
- Processing: Should be processed within 1 hour of collection for optimal yield; stat processing required for suspected meningitis
How our test process works!
