Other Available Methods

• Blood agar → haemolytic activity of bacteria

• Chocolate agar → recover fastidious (picky) bacteria

• MacConkey agar → lactose fermentation of bacteria

  • • • Lactose-fermenting organisms such as E. coli produce pink to red colonies.

      • Non-lactose fermenters such as Pseudomonas spp. produce colourless or pale colonies. 

• Sabouraud agar → fungal isolation

1. Biochemical Test

• Biochemical tests for Gram-positive bacteria:

  • Catalase test (Staphylococcus spp. vs Streptococcus spp.)

  • Coagulase test (CoPS vs CoNS)
    
    

• Biochemical tests for Gram-negative bacteria:

  • Indole test → tryptophan metabolism and indole production

  • Lysine iron agar (LIA) test → lysine decarboxylation, lysine deamination, and hydrogen sulfide production.

  • Mannitol fermentation test

  • Methyl Red (MR) test → mixed-acid fermentation of glucose.

  • Motility test → bacterial motility.

  • Oxidase test → presence of the enzyme cytochrome c oxidase.

  • Simmons citrate test → utilisation of citrate as the sole carbon source.

  • Triple sugar iron (TSI) agar test → carbohydrate fermentation and hydrogen sulfide production.

  • Urease test → urea hydrolysis.

  • Voges-Proskauer (VP) test → acetoin production from glucose fermentation.

* Commercial Identification Kits such as:

STAPHYtest (for Staphylococcus spp. detection)

ENTEROtest 24 N (for Enterobacteriaceae detection)

2. Molecular & Genomic Detection

• 16S rDNA PCR & Sanger Sequencing

• Whole Genome Sequencing (WGS)

  • Short: Illumina NovaSeq paired-end sequencing

  • Long: Oxford Nanopore sequencing  

• Shotgun Metagenomic Sequencing → bacteria, fungi, viruses identification as well as virulence & resistance-encoding genes

3. Antimicrobial Susceptibility Test

• Kirby-Bauer Disk Diffusion (CLSI/EUCAST Interpretation)

• D-tests using clindamycin and erythromycin disks → “D-shaped” inhibition zones are classified as resistant