Downloaded from www.microbiologyresearch.org by IP: 54.197.131.122 On: Tue, 08 Nov 2016 20:06:28 Association between HACEK bacteraemia and endocarditis Haur Sen Yew, 1 Stephen T. Chambers, 1,2 Sally A. Roberts, 3 David J. Holland, 4 Kylie A. Julian, 4 Nigel J. Raymond, 5 Justin Beardsley, 5 Kerry M. Read 6 and David R. Murdoch 1,2 Correspondence Haur Sen Yew yewha550@gmail.com David R. Murdoch David.Murdoch@cdhb.health.nz Received 29 October 2013 Accepted 28 March 2014 1 Christchurch Hospital, Christchurch, New Zealand 2 University of Otago, Christchurch, New Zealand 3 Auckland City Hospital, Auckland, New Zealand 4 Middlemore Hospital, Auckland, New Zealand 5 Wellington Hospital, Wellington, New Zealand 6 North Shore Hospital, Auckland, New Zealand We retrospectively examined medical records of 87 patients with bacteraemia caused by members of the HACEK group (Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Aggregatibacter aphrophilus, Aggregatibacter paraphrophilus, Cardiobacterium spp., Eikenella corrodens and Kingella spp.) to determine whether endocarditis was present, as defined by the Duke criteria. The overall positive predictive value (PPV) of HACEK bacteraemia for endocarditis was 60 %. The PPV varied with different HACEK species from 0 % (E. corrodens) to 100% (A. actinomycetemcomitans). The Duke criteria are an important diagnostic tool for infective endocarditis (Li et al., 2000). The isolation of a pathogenic micro-organism from blood cultures is a major criterion provided that two important features are met, namely the identification of a typical species of micro- organism and the presence of persistent bacteraemia. Persistent bacteraemia is defined as either (i) two positive blood cultures drawn .12 h apart, or (ii) a positive result in all of three or most of four or more separate blood cultures, with first and last specimens drawn at least 1 h apart. The HACEK group of bacteria (Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Aggregatibacter aph- rophilus, Aggregatibacter paraphrophilus, Cardiobacterium spp., Eikenella corrodens and Kingella spp.) are well- recognized causes of infective endocarditis and are infre- quently isolated from blood cultures of patients without endocarditis. Given the strong association between HACEK bacteria and endocarditis, we hypothesized that just one positive blood culture may be sufficient to make a diagnosis of HACEK endocarditis. The principal aim of our study was to determine the positive predictive value (PPV) of HACEK bacteraemia for the presence of endocarditis. METHODS A case was defined as a patient with at least one positive blood culture with a HACEK bacterium. Definitions of definite and possible infectious endocarditis were according to the Duke criteria (Li et al., 2000). Cases were identified from May 1979 to February 2011, through electronic databases from microbiology laboratories at Christchurch Hospital (Christchurch, New Zealand), Auckland City Hospital (Auckland, New Zealand), Middlemore Hospital (Auckland), North Shore Hospital (Auckland) and Wellington Hospital (Wellington, New Zealand). The clinical notes of all cases were reviewed and the relevant clinical information transcribed onto a standard data sheet. The clinical data obtained included patient demographics and co-morbidities, number of positive blood cultures, echocardiography findings, antibiotic therapy and mortality at 1 year. During review of the clinical notes, the diagnosis of endocarditis was determined in accordance with the modified Duke criteria by an infectious diseases physician or trainee, and was subsequently recorded in the data sheet. All data sheets were then analysed by H. S. Y., S. T. C. and D. R. M. Ethics approval was obtained from the New Zealand Ministry of Health Multi-region Ethics Committee. RESULTS Overall, 87 cases of HACEK bacteraemia were identified, of which 81 were from the period between 1995 and 2010. In total, 52 of the 87 cases had endocarditis (PPV 60 %). The characteristics of the cases by HACEK species are shown in Abbreviations: HACEK, Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Aggregatibacter aphrophilus, Aggregatibacter paraphrophilus, Cardiobacterium spp., Eikenella corrodens and Kingella spp; PPV, positive predictive value. Journal of Medical Microbiology (2014), 63, 892–895 DOI 10.1099/jmm.0.070060-0 892 070060 G 2014 The Authors Printed in Great Britain