Microbiology Laboratory

Identification and Molecular Techniques

Written by MicroDok

IDENTIFICATION TECHNIQUES

Identification technique is used to discover and categorize isolated microbial cultures in the microbiology laboratory. This technique is used to identify microorganisms to their precise species or strain level. Identification of microorganisms in the microbiology laboratory is often carried out using specific biochemical tests which is unique for a particular organism. Some biochemical tests or identification techniques employed in the microbiology laboratory for the identification of microbial pathogens include indole test, citrate test, urease test, motility test, Gram staining, sugar fermentation test, Voges Proskauer (VP) test, coagulase test, catalase test, optochin test, nitrate reduction test, oxidase test, starch hydrolysis test, determination of hydrogen sulphide production and methyl red test among others. Identification tests help microbiologists to identify a particular microorganism from a mixture of organisms; and they also assist microbiologists to put a name to a given pathogen. See section on “Biochemical Test Protocol” for detailed explanation of the many biochemical test used for the presumptive identification of bacteria in the microbiology laboratory using the biochemical identification technique.

MOLECULAR TECHNIQUES

Molecular techniques used in the microbiology laboratory include polymerase chain reaction (PCR) based tests which are employed for the identification of microorganisms from clinical specimens and other samples based on the identification of nucleotide sequences peculiar to each microbe. Molecular detection techniques usually employ DNA probes, gene chips and other gene amplification and sequencing techniques that allow microbiologists to detect pathogen-specific nucleotide sequences directly from clinically relevant specimen and other samples. They are important tool for the amplification of genes responsible for antimicrobial resistance in pathogenic microorganisms. Molecular techniques can also be used for the prompt identification of microorganisms especially bacteria from culture plates. Other molecular methods used for microbial characterization include nucleic acid sequencing and restriction fragment length polymorphism (RFLP).

REFERENCES

Atlas R.M (2010). Handbook of Microbiological Media. Fourth edition. American Society of Microbiology Press, USA.

Balows A, Hausler W, Herrmann K.L, Isenberg H.D and Shadomy H.J (1991). Manual of clinical microbiology. 5th ed. American Society of Microbiology Press, USA.

Basic laboratory procedures in clinical bacteriology. World Health Organization (WHO), 1991. Available from WHO publications, 1211 Geneva, 27-Switzerland.

Black, J.G. (2008). Microbiology:  Principles and Explorations (7th ed.). Hoboken, NJ: J. Wiley & Sons.

Garcia L.S (2010). Clinical Microbiology Procedures Handbook. Third edition. American Society of Microbiology Press, USA.

Garcia L.S (2014). Clinical Laboratory Management. First edition. American Society of Microbiology Press, USA.

Ira R (1995). Bacteriology, Standard Operative procedure manual for microbiology laboratories, National Institute of Biologicals.  Pp. 73-97.

Madigan M.T., Martinko J.M., Dunlap P.V and Clark D.P (2009). Brock Biology of Microorganisms, 12th edition. Pearson Benjamin Cummings Inc, USA.

Woods GL and Washington JA (1995). The Clinician and the Microbiology Laboratory. Mandell GL, Bennett JE, Dolin R (eds): Principles and Practice of Infectious Diseases. 4th ed. Churchill Livingstone, New York.

About the author

MicroDok

Leave a Comment