The Role of a Microbiologist

• Health and social care
• Further Education (Key Stage 5)

The Role of a Microbiologist

What does a medical microbiologist do?

Working in Healthcare Microbiology

Pathology is the study of disease. It is the bridge between science & medicine.

Consultant Medical Microbiologist --> doctor with specialist lab training

Job overview

Real-life story

Healthcare Scientist (e.g. Consultant Clinical Scientist) --> scientist with clinical training

Job overview

Real-life story

Biomedical Scientist --> lab-based analyst

Job overview

Real-life story

Medical microbiologists only work in a laboratory?

True

False

Culture & Microscopy Tests

Ajay Kumar Chaurasiya, CC BY-SA 4.0

Morphology

Bacteria and yeast grown on agar plates produce colonies of different visual appearances (shape, height, colour, opacity, consistency, etc.).

Chromogenic agar

Agar contains chromogenic substrates. Colony colour depends on production of different enzymes by the bacteria.

Helps differentiate between different bacteria that cause UTIs.

Bacteria (Staphylococcus aureus)

Tiny creamy spots

Fungi (various)

Often powdery or fuzzy.

Red = E.coli

Brown =  PPM group bacteria

Dark blue = KES group bacteria

Pale blue = Enterococci

Ford, 2019, Medical Microbiology

Gram staining

Bacteria stained with Gram stain and viewed under the microscope to check colour and morphology.

Differentiates between Gram-positive bacteria (e.g. S. aureus are purple cocci) & Gram-negative bacteria (e.g. E. coli are pink bacilli).

Y tambe, CC BY-SA 3.0

Biochemical Tests

CC BY-SA 3.0

Catalase test

Add bacteria to hydrogen peroxide. If the bacteria produce catalase, bubbles will be observed as the hydrogen peroxide is broken down and releases oxygen.

Helps differentiate between different bacteria, e.g. staphylococci (+) and streptococci (-).

Urease test

If the bacteria produce urease the pH indicator turns pink.

If they do not produce urease, the the pH indicator stays yellow.

Helps differentiate between different Enterobacteriaceae, e.g. Proteus (+) & Salmonella (-).

Coagulase

Bacteria are mixed with plasma. If bacteria produce coagulase, a clot is formed.

Used to help identify Staphylococcus aureus.

Ford, 2019, Medical Microbiology

ANew HanseN., CC BY-SA 4.0

No single biochemical test can identify a pathogen on its own!

Other Tests

PCR

Detects if genetic material from a named pathogen is present or not by trying to amplify it using primers specific to that pathogen.

E.g. Covid-19 PCR test detects genetic material from the SARS-CoV-2 virus.

Genome sequencing

Sequences the pathogen's genome & compares it to a database to identify it.

Mass Spec

Produces a molecular fingerprint based on the most highly abundant proteins in the pathogen. This can be compared to a database to identify the pathogen.

Immunoassays

Immunoassays (e.g. ELISA) can detect pathogens (via antigens) or the host's immune response (via antibody production).

E.g. HIV testing

Ajay Kumar Chaurasiya

CC BY-SA 4.0

Konrad Förstner CC BY 2.0

https://www.genome.gov/about-genomics/fact-sheets/Understanding-COVID-19-PCR-Testing

Ford, 2019, Medical Microbiology

learn.chm.msu.edu

Which antibiotics would be no use?

Which antibiotic would be the most effective?

Why is it important to treat patients with the right antimicrobial drug?

Antimicrobial Drugs

Microbiologists to help address the antimicrobial resistance (AMR) crisis by providing advice and education on use of antimicrobials.

Prevention measures:

• PPE
• Do hospital patients need to be isolated?
• Advice on how to reduce transmission in the community.

Read the article: Microbiology-The Science behind Cure and Prevention 

https://www.omicsonline.org/open-access/microbiologythe-science-behind-cure-and-prevention-2161-1165-1000260.php?aid=78857

Link

Assignment Focus

Analyse the role of the medical microbiologist in relation to disease control