A-Z of services

Microbiology department

The Microbiology Department will test patient samples to look for evidence of infection.

Who sends samples to Microbiology?

The department get many different types of sample sent in from GP surgeries, wards, outpatient departments, specialist clinics etc.

What type of samples?

The type of sample varies depending on where the infection is, examples of samples include: urine, faeces, sputum, wound swabs, nail, blood, pieces of tissue and environmental specimens.

What does Microbiology do with samples for bacterial culture?

Samples are sorted initially by Medical Laboratory Assistants (MLA) and registered onto the laboratory computer system. Samples sent to the laboratory for bacterial culture are placed onto agar plates. There are many different types of plates depending on the type of bacteria that you suspect may be causing the infection, some will grow a range of bacteria, while others will only grow specific bacteria e.g. a MRSA agar plate generally only grows MRSA. 

An example of what Microbiology do with a wound swab:

Following a wound swab, these samples would be cultured onto at least 3 different culture media by the Associate Practitioner (AP) and placed into different types of incubators for overnight incubation; the majority of these are set at body temperature 37oC.

The next day the Biomedical Scientist (BMS) would look at the plates and see if there were any bacteria growing that could cause infection. There are many different types of bacteria that could grow, some cause infection and others are harmless. Further tests are generally performed to identify the bacteria. When a bacteria causing infection (pathogen) is found sensitivity tests are performed to see what antibiotics your doctor can use.

At QE Microbiology there are two methods that we can use, we can do sensitivities on a culture plate or using a sensitivity analyser, either method will take another day to allow for the bacteria to grow again in the incubator.

Generally on the third day the antibiotic sensitivity will be examined and reported to the doctor.

Blood tests to look for evidence of infection.

For other infections Microbiology will test blood samples to look for antibodies to infection, these include looking for viral infections e.g. measles, chickenpox etc and also bacterial infections where we cannot grow the bacteria e.g. syphilis.  Samples are placed onto various analysers to test to see if there are antibodies present generally using a technique called ELISA.

Microbiology can also use this type of test to check if vaccination has worked e.g. with Rubella and hepatitis vaccines.

Other ways of looking for infection.

Microbiology use newer technology to look for infection using PCR, this looks for specific genes in bacteria and viruses. At present this technology is used to test samples for Chlamydia, Neisseria gonorrhoeae and Herpes simplex virus (HSV-virus causing genital warts or cold sores). PCR tends to be more expensive than serology tests or culture but does give very accurate results.

What else does Microbiology offer?

The consultant Microbiologist offers advice on clinical issues to your GP or hospital doctor, helping them to make a diagnosis or requesting more tests to aid diagnosis. They review all positive culture reports to ensure that the correct antibiotics are reported to your doctor.

They work collaboratively with the Infection Prevention and Control Team in the hospital to reduce the spread of infection, such as C. difficile, MRSA and other resistant bacteria.

Call us on 0191 482 0000

In emergencies dial 999 / Non-emergencies dial 111

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