Case Report Blood culture nega ve endocardi s – a suggested diagnos c approach Sadid F Khan Fi h Year Medicine (Undergraduate) Monash University
Sadid is a final year medical student at Monash University. He has a variety of interests, with par cular passion for infec ous diseases, public health and medical educa on.
This case report describes a previously healthy male pa ent with a subacute presenta on of severe cons tu onal symptoms, progressing to acute pulmonary oedema, and a subsequent diagnosis of blood culture nega ve endocardi s with severe aor c regurgita on. Blood culture nega ve endocardi s represents an epidemiologically varying subset of endocardi s pa ents, as well as a unique diagnos c dilemma. The cornerstones of diagnosis lay in careful clinical assessment and exposure history, as well as knowledge of common ae ologies and appropriate inves ga ons. The issues of clinically informed judgement and having a systema c approach to the diagnosis of these pa ents, especially within an Australian context, are discussed. Ae ological diagnosis of these pa ents modifies and directs treatment, which is fundamental in minimising the high morbidity and mortality associated with endocardi s.
Case Mr NP was a previously healthy, 47 year old Caucasian male who presented to a small metropolitan emergency department with two days of severe, progressive dyspnoea which was subsequently diagnosed as acute pulmonary oedema (APO). This occurred on a three month background of dry cough, malaise, lethargy and an uninten onal weight loss of 10 kilograms. History Apart from the aforemen oned, Mr NP’s history of the presen ng complaint was unremarkable. In the preceding three months Mr NP was previously treated in the community for pertussis and atypical pneumonia, resul ng in no significant improvement. Notably, this therapy included two courses of an bio cs (the specifics unable to be remembered by the pa ent), with the latest course completed the week prior to admission. He had no relevant past medical or family history, specifically denying a history of tuberculosis, malignancy, and heart and lung disease. There were no current medica ons or known allergies; he denied intravenous or other recrea onal drug use, reported minimal alcohol use, and had never smoked. Mr NP lived in suburban Melbourne with his wife and children. He kept two healthy dogs at home. There had been no sick contacts and no obvious animal or occupa onal exposures, although he noted that he occasionally stopped ca le trucks on the highway as part of his occupa on, but had no direct contact with the ca le. He recently Table 1. A suggested schema for assessing exposures to infec ous diseases during the clinical history, illustrated using the commonly used CHOCOLATES mnemonic.
Exposure Assessment Schemata: CHOCOLATES mnemonic Country of origin Household environment Occupa on Contacts Other: Immunisa ons, intravenous drug user, immunosuppression, splenectomy, etc. Leisure ac vi es/hobbies Animal exposures Travel and prophylaxis prior Ea ng and drinking Sexual contact
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travelled to Auckland, New Zealand for two weeks, two months prior. There were no stopovers, notable exposures or travel throughout the country. During the ini al assessment of Mr NP’s acute pulmonary oedema, blood cultures were drawn with a note made of oral an bio cs during the preceding week. A transthoracic echocardiogram (TTE) found moderate aor c regurgita on with le ventricular dilata on. A subsequent transoesophageal echocardiogram (TOE) noted severe aor c regurgita on, a one cen metre vegeta on on the aor c valve with destruc on of the coronary leaflet, LV dila on with preserved ejec on frac on greater than 50%. Blood cultures, held for 21 days, revealed no growth. Empirical an bio cs were started and Mr NP was transferred to a large quaternary hospital for further assessment and aor c valve replacement surgery. Examina on Examina on of Mr NP, a er transfer and admission, showed an alert man, pale but with warm extremi es, with no signs of shock or sepsis. Vital signs revealed a temperature of 36.2°C, heart rate of 88 beats per minute, blood pressure of 152/50 mmHg (wide pulse pressure of 102 mmHg) and respiratory rate of 18 breaths per minute, satura ng at 99% on room air. No peripheral s gmata of endocardi s were noted, and there was no lymphadenopathy. Examina on of the heart and lungs noted a loud diastolic murmur through the en re precordium, which increased with full expira on, but was otherwise normal with no signs of pulmonary oedema. His abdomen was so and non-tender with no organomegaly noted. Workup and Progress Table 2 shows relevant inves ga ons and results from Mr NP. Empirical an bio cs for culture nega ve endocardi s were ini ated during the ini al presenta on and were con nued a er transfer and admission: • • • •
Benzylpenicillin for streptococci and enterococci Doxycycline for atypical organisms and zoonoses Ce riaxone for HACEK organisms Vancomycin for staphylococcus and resistant gram posi ve bacteria.