General Microbiology Notes
Subject Overview
General Microbiology gives the historical and practical grounding for every microbiology paper that follows: the host-microbe relationship, safety in a clinical microbiology lab, the glassware and equipment used, and the theory and operation of light, fluorescent, phase-contrast and electron microscopes. It covers sterilization and disinfection principles in depth, biomedical waste management, and finishes with bacterial classification, growth and nutrition, culture media types, and aerobic/
Subject at a glance
4
Units
28
Topics
4
Credits
4
Infographics
Unit-wise Syllabus
4 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
- Definition and history of medical microbiology
- host-microbe relationship
- safety measures
- glassware care and handling
- equipment used in a clinical microbiology laboratory
Autoclave
Moist heat sterilisation
Hot air oven
Dry heat for glassware
Incubator
Grows cultures at 37 °C
Biosafety cabinet
Protects worker and sample
Microscope
Views microbes
Laminar air flow
Sterile work area
Study guide
This unit introduces medical microbiology: its definition and history, the host-microbe relationship, laboratory safety, glassware handling and equipment in a clinical microbiology lab. Learn the basic safety rules, since they apply in every laboratory you will ever work in.
- History and types of microscope — light
- DGI
- fluorescent
- phase contrast
- electron (transmission and scanning)
- principles and operational mechanisms of each
Bright-field light
Visible light through a stained sample
Routine stained smears
Phase contrast
Converts phase shifts into contrast
Living, unstained cells
Fluorescence
UV light excites fluorescent dyes
Auramine stain for TB, immunofluorescence
TEM
Electrons pass through thin sections
Internal ultrastructure
SEM
Electrons scan the surface
3D surface detail
Study guide
Microscopy is the main tool of the microbiologist. You study the history and types of microscope (light, dark-ground illumination, fluorescent, phase contrast, transmission and scanning electron) with their principles and working. Compare what each type of microscope is best used for.
- Definition
- types and principles of sterilization — heat (dry/moist, autoclave)
- radiation
- filtration
- efficiency testing of sterilizers
- antiseptics and disinfectants — types
- properties
- mode of action
- in-house preparation and efficiency testing
- biomedical waste management in a microbiology lab
Autoclave (moist heat)
121 °C, 15 psi, 15–20 min
Media, gowns, lab waste
Hot air oven (dry heat)
160 °C for 2 hours
Glassware, metal instruments
Filtration
0.22 µm membrane filter
Heat-sensitive liquids, antibiotics
Radiation
Gamma rays or UV
Disposables, surfaces
Study guide
You study sterilisation and disinfection: heat (dry and moist, autoclave), radiation and filtration, how sterilisers are tested, antiseptics and disinfectants, their properties and action, preparing and testing them and biomedical waste management. Learn autoclave settings and what a sterility indicator shows.
- General characteristics and classification of bacteria and fungi
- bacterial anatomy
- nutrition and growth requirements
- the bacterial growth curve
- synchronous/static/continuous cultures
- classification of culture media (solid, liquid, semisolid, synthetic, basal, enriched, selective, differential, transport, preservation, anaerobic)
- aerobic and anaerobic culture methods
- 1Lag phase
Adjusting, no division yet
- 2Log (exponential) phase
Rapid division
- 3Stationary phase
Growth = death
- 4Death (decline) phase
Cells die faster than they divide
Study guide
You study the classification and characteristics of bacteria and fungi, bacterial structure, nutrition and growth requirements, the growth curve, types of culture and the classification of culture media (solid, liquid, semi-solid, enriched, selective, differential, transport, anaerobic) and culture methods. Learn the phases of the bacterial growth curve and one example medium of each type.
Why General Microbiology Matters
Microbiology is a core diagnostic discipline, from detecting TB and typhoid to guiding antibiotic treatment. Sterilisation, culture and microscopy skills are used in every clinical laboratory and are the base for the later bacteriology papers.
How to Prepare for General Microbiology
- Learn the types of media and sterilisation methods with a table of uses.
- Practise handling the compound microscope until focusing is routine.
- Memorise the phases of the growth curve with a diagram.
General Microbiology: Frequently Asked Questions
What is the difference between sterilisation and disinfection?
Sterilisation destroys all microorganisms including spores, while disinfection reduces or removes harmful microbes on surfaces or objects but may not kill all spores.
What is selective and differential media?
Selective media allow only certain organisms to grow, while differential media show visible differences between organisms that grow on them.