The lab solving the hospital's biological mysteries

A patient’s samples arrive at the specimen reception desk of the microbiology team at Great Ormond Street Hospital (GOSH). A one-year-old girl is battling an infection following treatment for cancer found in her skull, and it’s now up to the Microbiology team to determine what the infection is and plan treatment.

Francis Yongblah, Deputy Laboratory Manager of the Microbiology unit at GOSH explains what happens to the sample next.


Scientist in the Microbiology unit
“We have a reception bench that’s manned by medical laboratory assistants (MLAs). They have an important role to check the quality of the sample and make sure we can use it. MLAs will also label samples with a unique identifier and will flag any urgent samples to Biomedical Scientists. They also have a responsibility for ensuring that the sample is set up for the appropriate test. It is crucial to get this correct at the beginning as a mistake can lead to a delayed result.”

Each sample could possibly contain a different set of infectious bugs to look for. For this reason each specimen has a different procedure for testing in order to capture the infectious bug. Often the pathology team will receive requests to test for specific infections, but sometimes the work is a bit more complex than that. The sample from the young girl on the oncology ward is a complex one.

After receiving chemotherapy, the patient’s immune system is not working, putting her at severe risk of contracting a dangerous infection. The medical team has sent multiple samples for testing, in order to detect and then treat any underlying infections. The pathology team are told that a scan of the patient’s chest suggested a chronic fungal infection in her lungs.

Testing begins

Decoding infections can be tricky – but the pathology team systematically work through tests to pinpoint the cause of infection and devise a treatment strategy.

Agar plates in the microbiology unit
“We just take one step at a time. There’s many different tests that we use. In microbiology, we’ve got two different sections – we’ve got virology and bacteriology. In bacteriology, the main focus is culture – trying to grow live bacteria. We’re hoping the bacteria taken from the patient are still alive so that we can grow it on agar and do sensitivity testing.”

Sensitivity testing bombards the bacterial cultures with a range of antibiotics in an attempt to find a combination that treats the patient’s infection but can be given in a safe dose. After such testing, the girl battling infections following treatment for cancer was treated with a combination of antibiotic drugs, picked to target her specific infections. Francis explains how the findings from the laboratory are translated across to the wards.

“We have a medical team here – three consultants and a registrar. Often, they contact doctors or nurses around the wards just to inform them that a patient may have an infection, what the appropriate antibiotics are to use.”

Additional testing

The clinical picture from the specimens taken from the girl battling an infection on the ward suggests a bacterial infection, but the sample was sent to the Virology team to hunt for a viral infection. The Virology team largely uses a chemical process known as the polymerase chain reaction to detect DNA or RNA which indicates presence of viruses.

After being subjected to various molecular tests to look for the presence of viruses, all tests are negative.

Treating the patient

The Microbiology and Virology team at GOSH – hidden at the end of a corridor, behind a secure door and up a few flights of stairs – could be described as unsung heroes in the stories of lots of the patients and families who pass through the hospital. Many families and young people will be aware that samples are taken and that drugs are given, but the workings of the pathology lab might remain a mystery – a black box into which samples go and medicine comes out.

Even so, the team still understand that they play a crucial role for patients receiving treatment at GOSH. Francis reminds his team that there is often a seriously ill child at the end of the samples which get sent to the pathology lab.

“I think one thing that makes us stay focused is we have a good clinical team who do ward rounds and work in the lab as well. They see the patient and will often come back and inform us what’s going on with the patient. It makes the work that you’re doing more significant.”

Back to the ward

The young girl battling infections following treatment for cancer was prescribed a variety of antibiotics and antifungals. Many of these were potentially quite dangerous if given at too high a dose, so the Pathology team monitored the levels of these drugs throughout treatment. The team were also able to recommend counselling for the child’s parents since many of the treatments, while needed to treat difficult infections, also carried a risk of causing side effects.

“I think the parents were aware of how much work we had been doing, they sent us a card to say ‘thank you for all the hard work’.

“And that was nice to get that appreciation, because I don’t think a lot of people are aware of pathology or microbiology.”

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