Microscopy, culture, organism identification and susceptibility testing
What the Gram stain tells you and why, blood culture volume and contaminants, specimen quality, MALDI-TOF identification, MICs and EUCAST breakpoints (S, I and R), inducible resistance traps, and using PK/PD targets such as vancomycin AUC/MIC to decide if "susceptible" is enough.
Tier 1Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The laboratory answers three questions in order: is there an organism (microscopy, culture), what is it (identification) and what kills it (susceptibility).
- A result is only as good as the specimen: right site, before antibiotics, enough volume, transported quickly.
- MIC is the lowest concentration that inhibits visible growth. Breakpoints turn it into S, I or R. Most Australian laboratories use EUCAST breakpoints (v16.1 in 2026).
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Sources
- EUCAST clinical breakpoint tablesEuropean Committee on Antimicrobial Susceptibility Testing, v16.1, valid 24 June to 31 December 2026
- RCPA ManualAU/NZRoyal College of Pathologists of Australasia, online edition, accessed November 2026
- Therapeutic Guidelines: AntibioticAU/NZTherapeutic Guidelines Limited (eTG complete), accessed November 2026
- Therapeutic monitoring of vancomycin for serious MRSA infections: a revised consensus guideline (ASHP, IDSA, PIDS, SIDP)Am J Health Syst Pharm 2020;77:835-64 (Rybak MJ et al.), 2020
- A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2024 update (IDSA and ASM)Clin Infect Dis 2024;ciae104 (Miller JM et al.), 2024
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback