I have been told many times recently by GPs and other Microbiologists that there is no point doing a throat swab from patients with pharyngitis because there is now the Centor score that allows you to identify the Group A beta-haemolytic streptococcus, Streptococcus pyogenes, without having to send any tests to the microbiology laboratory. But is this true or is Centor like the half-man half-horse Centaur - a myth?

I was walking down the corridor when one of the Medical Registrars walked passed looking perplexed, we said hello and passed on by, then he called after me “oh can I ask your opinion on…” A standard start to many a query for a Microbiologist! But this question was different, he was reading around the subject of endocarditis and was frustrated by the “guidelines” put out there by the expert bodies… he went on “their advice is sometimes different and even contradictory! How do you know what to follow?”
 
I agreed, which didn’t seem to satisfy him at all. So let me explain further in this blog, as it will take longer than a passing corridor conversation, unless you have the old Victorian corridors still, I may be able to explain it in the time it takes to walk one of those, ah the days when we all got more exercise at work.

A patient comes in to hospital with severe central abdominal pain. They are febrile, tachycardic and hypotensive. They are diagnosed with acute pancreatitis based upon a high amylase blood test and admitted under the surgeons. As they are so unwell they are transferred to the surgical high dependency unit. The Surgical Registrar calls the duty Microbiologist to ask whether to start antibiotics in her patient. The Microbiologist does the usual “microbiologist thing” asking a question rather than answering the one posed; “does the patient actually have an infection?” The Surgical Registrar stares at the phone. The Microbiologist continues “perhaps I should ask…why do you want to give antibiotics in pancreatitis”?

​A 37 year old lady was brought in to the Emergency Department having fallen off her horse, which had then accidentally stepped on her. The patient had severe left upper quadrant abdominal pain and marked hypotension. A probable splenic injury was diagnosed and she was taken to theatre. Her spleen had been badly damaged and had to be removed (splenectomy) in order to control the bleeding. After she was back on the ward and stable the doctors called the Microbiologists to ask whether she should be immunised and what antibiotics she should be on.

Patient A is immunocompromised from leukaemia and has a cough and severe shortness of breath not responding to antibacterials, patient B is on chemotherapy for melanoma and has a headache and proptosis (bulging eyeball) and patient C is HIV positive and has meningitis. All these patients have one thing in common; they have an invasive fungal infection. These infections are often hard to diagnose, difficult to treat and delayed management leads to a poor outcome for the patients. Invasive fungal infections are a particular problem for immunocompromised patients, those on critical care units or those with long-term disorders such as chronic lung diseases.
 
Many patients have to start empirical treatment with antifungals whilst awaiting results from reference laboratories as there is often a lack of locally available diagnostic tests. This results in a lot of unnecessary treatment of patients with potentially toxic and expensive drugs. In fact, antifungals are often the most expensive drugs used within hospitals; using better diagnostics could produce significant cost savings. To give you an idea, the listed drug costs in the BNF for one day of antifungal treatment for a 70kg patient are:

• IV AmBisome (5mg/kg OD) = £700
• IV Caspofungin (50mg OD) = £330
• IV Voriconazole (4-6mg/kg BD) = £300

Mr Jones comes in to your clinic asking about antibiotic
prophylaxis for a dental procedure he is having next week. He had his aortic valve replaced 5 years ago and shortly afterwards he had some dental work done where he was given prophylactic antibiotics to stop his heart valve becoming infected. This time he has been told that he doesn’t need any antibiotics and yet he is having the same
dental procedure done. He’s wondering why he needed
antibiotics before and not now? What has changed? He’s very anxious and has come to you looking for guidance.