microbio

• Biological Safety Cabinet


  Allows room air to pass into cabinet and around the area and material within, sterilizing only the air to be exhausted
• Classes of Biosafety Cabinet

  • Class I
  • Class II
  • Class II A
  • Class II B
• Class I Biosafety Cabinet

  1. Consist of negative pressure

  2. Operated in Open front
• Class II Biosafety Cabinet

  1. Air flows in "sheets", serves as barrier to particle from outside the cabinet

  2. Direct Flow of contaminated air into the filters

  3. Also called as VERTICAL LAMINAR FLOW BSC's

  4. Self-Contained, and 70% of the air is recirculated

  5. Selected for radioisotopes, toxic or carcinogenic materials
• Microbiology


  • Acellular Infectious Agents
  • Cellular Micro-organisms
• Acellular Infectious Agents


  • Prions (CJD)
  • Viruses (HIV/AIDS)
• Cellular Micro-organisms


  • Procaryotes
  • Eucaryotes
• Procaryotes


  • Archaea
  • Bacteria
• Eucaryotes


  • Algae
  • Fungi (Athlete's Foot)
  • Protozoa (Malaria)
• Virus


  • Completely dependent of the cells they infect for their survival and replication
  • Very simple microbes, consisting of Nucleic Acid, few proteins, and lipid envelope (Not all)
• Bacteria


  • Have both RNA & DNA, metabolic machinery for self-replication, and a complex cell wall struct.
  • Prokaryotic – simple unicellular organisms
• Fungi


  • Divided into 2 different kinds, Yeasts are single-celled organisms, Molds: Multi-celled organism
  • Few medically members exist on both forms (Dimorphic fungi)
• Parasites


  • Protozoa: Single-Celled
  • Worms/Bugs: Multi-celled organisms
• Bacteria

  • Prokaryotic lack true nucleus and nuclear membrane
  • Nucleoid: Single, Closed, Circular Chromosomes
  • Plasmids: small circular molecules of extrachromosomal circular DNA
  • May Either be a Gram + or Gram -
  • Binary fission: Asexual bacteria
  • Siza: range of 0.2 to 2 um in diameter and 1-6um in length
• Gram Stain

  • Principal stain used for examination of bac.
  • First devised by HANS CHRISTIA GRAM IN late 19th century
  • Divided most bact. Sp. Into two large groups
  • Gram Pos.: Take up the basic dye, crystal violet
  • Gram Neg.: allow crystal violet to washout easily with decolorizer alcohol or acetone
• Gram Positive vs Gram Negative

  • Cell Wall: Thick (Peptidoglycan) vs Thin (Peptidoglycan)
  • Lipopolysaccharide (PS): Absence vs Presence
  • Gram Staining: Purple vs Red or Pink
• Bacterial Morphologies


  • COCCI: Spherical-shaped
  • BACILLI: Rod-Shaped
  • SPIRILLA: Spiral-Shaped
  • VIBRIOS: Comma-Shaped
• Bacterial Metabolism


  • Fermentation: catabolize carbohydrates to produce energy
  • Respiration: Oxidation
  • Aerobic: Presence of Oxygen, Sugar to ATP
  • Anaerobic: Without absence of Oxygen, Fermentation
• Specimen Collection Safety


  • Universal Precautions: Wearing Gloves and Lab. Gown, Eye protection also be worn if splashing, Accident or Injuries (needle prick) must be reported immediately
• Specimen Collection Guidelines


  • Specimen should be alone from the infection site, not contaminated by the surrounding area
  • Specimen should be collected before antimicrobials are administered (Antibiotics)
  • Appropriate collection devices should and must be sterile, Aseptic Technique is required
  • Specimen container should be labeled with patient's identification, the date and time of collection and the source of specimen
• Specimen Collection Sites


  • Throat (Swabs)
  • Sputum
  • Stool
  • Urine
  • Blood
  • CSF
  • Genital Tract
• Specimen Handling & Transport

  • Anerobic specimen must be transported win an anerobic system
  • Swab samples are not allowed to dry out
  • Most specimen can be held at 2 Celsius to 8C if transport cannot occur immediately EXCEPT: Temperature-sensitive organisms, Blood Culture Bottles, CSF (Cerebrospinal Fluid)
• Specimen Processing


  • Nutritive Media
  • Differential media
  • Selective Media
  • Backup Broth
  • Specialized Media
  • Incubation
• Specimen Rejection Criteria


  • Specimen received in nonsterile or contaminated containers
  • Contaminated with barium or other foreign substances
  • 24-hour urine or sputum collections
  • Saliva instead of sputum
  • Unref. Urine specimens 2hrs or more post-collection