Dr Fiona Cooke: Managing endocarditis
Having been healthy all his life, much of which he spent as an academic doctor, Richard Himsworth has recently had problems that have been tricky to tease apart. He had his aortic valve replaced in 2008 and made a good recovery. However, he experienced breathlessness – probably due to cryptogenic organising pneumonia (COP) – for which he was taking steroids. Despite this, he was able to lead a normal life, with activities in London and Cambridge, and holidays to Sicily – until October 2018.
Over three days in October 2018, I didn’t feel quite myself. I was muddled, and had difficulty finding the right words, so my wife took me to the emergency department. There was nothing to find on clinical examination, and a CT scan of my brain was normal. The paramedics had recorded a fever, and my white cell count and C-reactive protein were raised, all pointing towards an infection. A urine dipstick was abnormal, so I was discharged home with a five-day course of co-amoxiclav for a possible urine infection.
The following day I received a phone call from the hospital to say that they had grown enterococcal bacteria from my blood sample, necessitating my return to hospital. An ultrasound scan of my heart showed thickening of my valve replacement, which, together with the bacteria in my bloodstream, pointed towards bacterial infection of my replacement valve – this is called infectious endocarditis.
The management of endocarditis hasn’t changed much since I was a junior doctor. I needed to have six weeks of intravenous antibiotics, which didn’t fill me with joy. I was initially on the infectious diseases ward (tenth floor) with a lovely view. I was allowed out for short visits, then on weekend leave. Antibiotics can have side effects, and I had problems with rashes and kidney function. Other choices of antibiotics were limited, but I was able to be transferred to the OPAT (outpatient antimicrobial therapy) service for a new once-daily antibiotic, daptomycin.
All went well initially, and I enjoyed being at home, but unfortunately I ran into problems with increasingly severe breathlessness. The likely diagnosis was eosinophilic pneumonitis, a recognised side effect of daptomycin, so my antibiotics were changed yet again and I came back into hospital for the rest of my course. I am still a little breathless, and have developed an ankle ulcer, but from the endocarditis side of things, all appears to be well.
The consultant’s view: Dr Fiona Cooke
Richard’s blood samples were incubated urgently, looking for growth of bacteria. One of the biggest recent advances has been the MALDI (matrix-assisted laser desorption/ ionisation) machine for rapid identification of bacteria. Previously, we would have to wait 24 hours for bacterial growth on an agar plate. We can now get a result in four hours, allowing timely advice on clinical and antibiotic management of patients with infections. When Richard’s samples flagged positive, we saw bacteria – specifically, Gram-positive cocci in short chains – and the MALDI identified these as enterococci, which caused Richard’s endocarditis.
The management of endocarditis usually involves four to six weeks of intravenous antibiotics, although recent studies suggest short courses may sometimes be effective. We have had an OPAT service for ten years, allowing patients to go home and attend hospital once a day for antibiotic therapy. Our hospital has also trained patients and their relatives to administer intravenous antibiotics at home.
All current OPAT patients are discussed at the weekly multidisciplinary meeting attended by the duty consultant microbiologist. We provide extra information about additional antibiotic options, as up to 10% of OPAT patients develop antibiotic allergies. Microbiologists are trying to reduce the use of antibiotics to prevent antimicrobial resistance, but when people like Richard need them, we make sure they are on the right drug, at the right dose, by the right route for the right length of time.