Clinical Microbiology and Infectious Diseases

Diagnosing Infectious Diseases

• Pathology Department Organization:
  • Anatomical Pathology (Electron Microscopy, Morgue/Autopsy, Histopathology, Cytology Lab, Cytogenetics Lab)
  • Clinical Pathology (Clinical Microbiology, Clinical Immunology, Hematology, Hematopathology, Blood Transfusion Bank, Clinical Chemistry)
  • Bacteriology (part of CML in larger hospitals, but sent to reference labs in smaller hospitals)
  • Mycobacteriology (part of CML in larger hospitals, but sent to reference labs in smaller hospitals)
  • Virology (part of CML in larger hospitals, but sent to reference labs in smaller hospitals)
  • Immunology (independent in larger hospitals, part of CML in smaller hospitals)
  • Mycology
  • Parasitology

Clinical Microbiology Lab (CML)

• Mission: Active participation in managing patients with infectious diseases.
• Responsibilities:
  • Processing clinical specimens
  • Isolating potential pathogens
  • Identifying isolated pathogens
  • Antibiotic sensitivity testing (AST)
  • Hospital outbreak recognition and source identification (environmental samples, healthcare worker screening)

Clinical Specimens

• Collection:
  • Collected from patients to diagnose or monitor infectious diseases.
  • Components for High-Quality Specimens:
    • Proper specimen selection
    • Correct techniques for collection (detailed instructions to patient, standard precautions, pre-antimicrobial therapy, sufficient quantity, sterile container, proper labeling)

Processing Clinical Specimens

• Specimen Type Variations:
• Macroscopic Examination/Naked-Eye:
• Microscopic Examination: (wet mount/staining) - direct examination, on specimens' what could be seen, or on next day's isolated colonies.
• Culture Media Inoculation: appropriate culture media→pure growth
• Identification & AST(Antibiotic Sensitivity Test): directly on specimens or on next day's isolated colonies

Additional Notes

• Urine Specimen Collection:

  • Clean catch mid-stream
  • Catheterized specimens
  • Urine bags (babies)
  • Suprapubic needle aspiration (SPA)

• Urine Processing Time: within 30 minutes of collection or 24 hours refrigerated

• Specimen Rejection Criteria: Leaked containers, insufficient quantity (QNS), specimens sent in formalin.

• Specimen Transport: As soon as possible (no delay); properly stored.

• Specimen Processing: vary according to the type of specimen.

• Quantitative Bacterial Colony Count: Colony-forming units (CFU) are used to determine the number of viable bacteria per mL of urine. Factors like calibrated loops and dilution influence the CFU calculation.

• Results/Interpretation: Criteria to determine clinical significance include patient's details, specimen type, growth patterns, and pathogen counts.

Additional Topics

• Blood Culture Specimens: aseptic technique used with precautions.
• Cerebrospinal Fluid (CSF): CSF collection and processing (include macroscopic and microscopic examination).
• Wound Specimens: preferable ASPIRATE (syringe) technique.
• Feces/Stool Specimen Collection: Collect stool sample using clean (unsterile) container, add preservative, prompt transport to lab, and process within 2 hours. Includes microbial pathogens like Salmonella and Shigella.

Explore the intricate processes and responsibilities within the Clinical Microbiology Lab (CML) as it relates to diagnosing infectious diseases. This quiz covers various aspects of pathology organization, including microbiology, immunology, and the handling of clinical specimens. Test your knowledge on the essential roles these departments play in patient management.