Micro Bio 02/20

Biofilms

• Definition: A biofilm is a layer of microbial slime consisting of bacteria and extracellular polymeric substances (EPS) that adheres to surfaces.

• Formation: Bacterial cells stick to a surface and produce EPS, which acts as a protective matrix.

• Common Locations: Biofilms are ubiquitous in the environment, present on:

  • Teeth (as dental plaque)

  • Water supplies

  • Air conditioning units

  • Food processing facilities

  • Various surfaces in healthcare settings.

Bacterial Behavior in Biofilms

• Survival and Communication: Inside biofilms, bacteria can:

  • Communicate with each other

  • Feed

  • Grow

• Resistance: Bacteria in biofilms are approximately 200 times more resistant to antibiotics and disinfectants.

• Threat to Patients: Persisting biofilms pose significant health risks until they are disturbed, allowing bacteria to disperse to other surfaces through contact.

Wightly Corporation

• Role in Biofilm Management: Wightly Corporation specializes in combating biofilms and removing infectious organisms in clinical settings through innovative systems and products.

Experiment Focus

• Laboratory Experiment: In the upcoming lab, students will test various antibiotics, disinfectants, and antiseptics against biofilms.

• Agent Selection: Not all agents are effective against every microorganism; understanding their spectra of activity is crucial.

Example Study

• Research Collaboration: The speaker references a study on disinfecting intravenous access ports to decrease bloodstream infections.

• Data Presentation: The effectiveness of treatments is tracked:

  • Blue bars: Results after the immediate application of bacteria

  • Red bars: Results after the bacteria had dried.

Sterilization Techniques

• Concept of Equivalent Treatments: There are multiple methods to achieve sterilization:

  • High heat for a short duration

  • Low heat for an extended duration

• Example of Pasteurization: Involves low temperature over time or high temperature for a brief time to kill pathogens.

Types of Radiation for Sterilization

• Ionizing Radiation:

  • High-energy methods like X rays and gamma rays destroy DNA in cells.

• Non-ionizing Radiation:

  • Includes UV light used for sterilizing surgical theaters and hoods due to its ability to induce lethal mutations in bacteria.

Pyrogens

• Definition: Pyrogens are substances that induce fever in the body.

• Historical Context: Previously prepared IV solutions in large glass bottles suffered from pyrogen contamination; hence the term was coined.

Antimicrobial Agents

• Triclosan: Once common in various products but found to be no more effective than alternatives.

• Bleach: Effective on inanimate objects; caution is needed to avoid corrosion on certain metals.

• Silver Nitrate: Historically used in newborns' eyes to prevent infection; still used in dilute solutions for certain treatments.

Evaluation of Antibiotic Effectiveness

• Testing Method: Using discs with different agents applied to agar:

  • A clear zone around a disc indicates susceptibility (resistance is indicated if growth reaches the edge).

• Concentration Metrics:

  • Minimum Inhibitory Concentration (MIC): Lowest concentration that inhibits microbial growth.

  • Minimum Bactericidal Concentration (MBC): Lowest concentration required to kill the microorganisms.

Safety and Regulations

• Historical Toxicity: Some agents like ethylene oxide were phased out due to their toxicity and health risks.

• Gram Staining in Bacteria: Understanding the differences can help in treatment choices, as gram-positive bacteria generally have lower resistance compared to gram-negative bacteria.