Microbiology (ATC)

Controlling microbes prevents infection.

• Sterilization kills all microbes (e.g., autoclave).
• Disinfection kills most microbes on surfaces.
• Sanitization reduces microbes to safe levels.
• Method choice depends on the setting and risk.

Microbes cause many diseases.

• Pathogens include bacteria, viruses, fungi, and parasites.
• Diseases spread by contact, air, food, water, and vectors.
• Signs and symptoms guide diagnosis.
• Understanding the cause guides treatment.

Breaking the chain of infection stops disease spread.

• The chain: agent, reservoir, portal of exit, transmission, portal of entry, host.
• Hand hygiene and PPE are key defenses.
• Transmission can be direct or indirect.
• Standard precautions protect everyone.

HAIs are infections acquired in health-care settings.

• Examples: MRSA, C. diff, CAUTI, and surgical site infections.
• Often linked to devices and procedures.
• Hand hygiene and sterile technique reduce them.
• HAIs are a major patient-safety concern.

Microbiology grew from key discoveries.

• Leeuwenhoek first saw microbes with a microscope.
• Pasteur disproved spontaneous generation and developed pasteurization.
• Koch linked specific microbes to specific diseases.
• These advances founded germ theory.

The body and medicine fight microbes together.

• Innate immunity is general; adaptive is specific.
• Immunity can be active (from infection/vaccine) or passive (from antibodies).
• Vaccines train the immune system.
• Antimicrobials (antibiotics, antivirals) treat infection; overuse causes resistance.

Lab tests identify infectious agents.

• Cultures grow organisms for identification.
• Gram stain classifies bacteria.
• Sensitivity testing guides antibiotic choice.
• Molecular tests (PCR) detect pathogens quickly.

Many microbes reproduce asexually.

• Binary fission splits one cell into two (bacteria).
• Other forms include budding and spore formation.
• Asexual reproduction is fast and produces clones.
• Rapid growth can cause quick infection spread.

Molds are multicellular fungi.

• Molds grow as hyphae forming a mesh (mycelium).
• They reproduce by spores.
• Some cause disease or spoil food; others make antibiotics (penicillin).
• They thrive in warm, moist environments.

Living things are classified systematically.

• Taxonomy ranks organisms from domain to species.
• Three domains: Bacteria, Archaea, and Eukarya.
• Binomial nomenclature gives genus and species names.
• Classification reflects evolutionary relationships.

Prokaryotes are simple cells without a nucleus.

• Bacteria have no membrane-bound organelles.
• Shapes include cocci, bacilli, and spirilla.
• They have a cell wall (peptidoglycan).
• Some form protective endospores.

Stains make microbes visible under a microscope.

• Gram stain separates gram-positive (purple) from gram-negative (pink).
• Acid-fast stain identifies TB bacteria.
• Simple and differential stains reveal structure.
• Staining aids identification.

pH affects microbial growth.

• The pH scale runs 0–14 (acidic to basic).
• Most microbes prefer near-neutral pH.
• Extreme pH inhibits or kills microbes (a preservation method).
• Some microbes tolerate acid or base extremes.