Applied Bacteriology Notes
Subject Overview
Applied Bacteriology takes the diagnostic microbiology skills built earlier and applies them to real infection-control practice — antibiotic susceptibility testing (Kirby-Bauer and Stokes methods, MIC/
Subject at a glance
3
Units
14
Topics
1
Credits
3
Infographics
Unit-wise Syllabus
3 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
- Definition of antibiotics
- culture media for AST
- inoculum preparation and standardization
- control bacterial strains
- choice of antibiotics
- MIC and MBC concepts and determination
- Kirby-Bauer and Stokes methods
- tests for beta-lactamase production
- 1
Prepare inoculum
Match 0.5 McFarland standard
- 2
Swab Mueller-Hinton agar evenly
- 3
Place antibiotic discs
- 4
Incubate at 35–37 °C for 16–18 hours
- 5
Measure zones of inhibition
In mm
- 6
Interpret
Sensitive, intermediate or resistant (CLSI or EUCAST)
Study guide
This unit covers antibiotic susceptibility testing: culture media, inoculum standardisation, control strains, choice of antibiotics, MIC and MBC, Kirby-Bauer and Stokes methods and beta-lactamase tests. Understand how the zone of inhibition is interpreted.
- Bacteriological examination of air (settle plate method, air sampling instruments)
- sterility testing of IV fluids
- bacteriological surveillance of the hospital environment
- role of the microbiology laboratory in nosocomial infection control
Surveillance
Track infection rates
Environmental sampling
Air, surfaces, water
Sterility testing
IV fluids, equipment
Outbreak investigation
Typing the organism
Antibiogram
Guide empirical antibiotic use
Study guide
You study air bacteriology (settle plate and sampling), sterility testing of IV fluids, bacteriological surveillance of the hospital environment and the laboratory's role in controlling nosocomial infection. Know why hospital-acquired infections are a major concern.
Basic concepts and rationale for preserving microbes, principle and procedures of preservation methods with special reference to lyophilization
Subculturing
Transfer to fresh media regularly
Weeks
Refrigeration
2–8 °C
Weeks to months
Glycerol stocks at −80 °C
Deep freeze
Years
Lyophilisation
Freeze-drying under vacuum
Many years
Study guide
You study why microbes are preserved and the principles of preservation methods, especially lyophilisation. Learn the advantages of freeze-drying for long-term storage.
Why Applied Bacteriology Matters
Antibiotic susceptibility testing guides treatment and fights antibiotic resistance, so these skills are among the most clinically important in microbiology.
How to Prepare for Applied Bacteriology
- Learn the Kirby-Bauer method step by step.
- Understand MIC and MBC with a simple diagram.
- Read about antimicrobial resistance for current context.
Applied Bacteriology: Frequently Asked Questions
What is MIC?
The minimum inhibitory concentration is the lowest concentration of an antibiotic that prevents visible growth of a microorganism.
What is a nosocomial infection?
A nosocomial infection is an infection acquired in a hospital or healthcare setting.