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 have a patient with possible infective endocarditis, what antibiotics should I start” exclaimed the excited junior doctor.
“What makes you think they have infective endocarditis?” replied the much calmer Microbiologist.
“They have a high temperature and a prosthetic heart valve and splinter haemorrhages” responded the junior doctor, “so what antibiotics should I start?”
“Okay” said the Microbiologist, “but that's not enough to prove infective endocarditis on their own, let’s talk about Duke’s criteria…”
“But the splinter haemorrhages...surely they have infective endocarditis!?” pleaded the junior doctor.
But the Microbiologist went on and explained further…
So what is infective endocarditis (IE)?
Infective endocarditis is an infection of the endocardium of the heart, either on native heart tissue or prosthetic heart valves. IE usually implies infection of the heart valves; however infection can also be related to transmural thrombosis and congenital heart defects such as atrioseptal defects and ventriculoseptal defects. Microbiologists also often include other intra-cardiac device related infections in the diagnosis of IE e.g. pacemakers and implantable cardioverter defibrillators.
In IE an infected mass, called a vegetation, builds up on the heart tissue or valve. The vegetation is made of bacteria, fibrin and platelets and without treatment it will continue to grow until bits break off (emboli) and fly around the body or the valve itself is so badly damaged that the heart cannot function properly anymore and fails.