Clinical characteristics and outcome of infective endocarditis due to Abiotrophia and Granulicatella compared to Viridans group streptococci.

OBJECTIVE: To describe the clinical characteristics and outcome of Abiotrophia and Granulicatella infective endocarditis and compare them with Viridans group streptococci infective endocarditis. METHODS: All patients in the International Collaboration on Endocarditis (ICE) - prospective cohort study (PCS) and the ICE-PLUS cohort were included (n = 8112). Data from patients with definitive or possible IE due to Abiotrophia species, Granulicatella species and Viridans group streptococci was analyzed. A propensity score (PS) analysis comparing the ABI/GRA-IE and VGS-IE groups according to a 1:2 ratio was performed. RESULTS: Forty-eight (0.64%) cases of ABI/GRA-IE and 1,292 (17.2%) VGS-IE were included in the analysis. The median age of patients with ABI/GRA-IE was lower than VGS-IE (48.1 years vs. 57.9 years; p = 0.001). Clinical features and the rate of in-hospital surgery was similar between ABI/GRA-IE and VGS-IE (52.1% vs. 45.4%; p = 0.366). Unadjusted in-hospital death was lower in ABI/GRA-IE than VGS-IE (2.1% vs. 8.8%; p = 0.003), and cumulative six-month mortality was lower in ABI/GRA-IE than VGS-IE (2.1% vs. 11.9%; p<0.001). After PS analysis, in-hospital mortality was similar in both groups, but six-month mortality was lower in the ABI/GRA IE group (2.1% vs. 10.4%; p = 0.029). CONCLUSIONS: Patients with ABI/GRA-IE were younger, had similar clinical features and rates of surgery and better prognosis than VGS-IE.

HACEK infective endocarditis: characteristics and outcomes from a large, multi-national cohort.

The HACEK organisms (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) are rare causes of infective endocarditis (IE). The objective of this study is to describe the clinical characteristics and outcomes of patients with HACEK endocarditis (HE) in a large multi-national cohort. Patients hospitalized with definite or possible infective endocarditis by the International Collaboration on Endocarditis Prospective Cohort Study in 64 hospitals from 28 countries were included and characteristics of HE patients compared with IE due to other pathogens. Of 5591 patients enrolled, 77 (1.4%) had HE. HE was associated with a younger age (47 vs. 61 years; p<0.001), a higher prevalence of immunologic/vascular manifestations (32% vs. 20%; p<0.008) and stroke (25% vs. 17% p = 0.05) but a lower prevalence of congestive heart failure (15% vs. 30%; p = 0.004), death in-hospital (4% vs. 18%; p = 0.001) or after 1 year follow-up (6% vs. 20%; p = 0.01) than IE due to other pathogens (n = 5514). On multivariable analysis, stroke was associated with mitral valve vegetations (OR 3.60; CI 1.34-9.65; p<0.01) and younger age (OR 0.62; CI 0.49-0.90; p<0.01). The overall outcome of HE was excellent with the in-hospital mortality (4%) significantly better than for non-HE (18%; p<0.001). Prosthetic valve endocarditis was more common in HE (35%) than non-HE (24%). The outcome of prosthetic valve and native valve HE was excellent whether treated medically or with surgery. Current treatment is very successful for the management of both native valve prosthetic valve HE but further studies are needed to determine why HE has a predilection for younger people and to cause stroke. The small number of patients and observational design limit inferences on treatment strategies. Self selection of study sites limits epidemiological inferences.

Phylogenetic analysis of viridans group streptococci causing endocarditis.

Identification of viridans group streptococci (VGS) to the species level is difficult because VGS exchange genetic material. We performed multilocus DNA target sequencing to assess phylogenetic concordance of VGS for a well-defined clinical syndrome. The hierarchy of sequence data was often discordant, underscoring the importance of establishing biological relevance for finer phylogenetic distinctions.

Genotypic diversity of coagulase-negative staphylococci causing endocarditis: a global perspective.

Coagulase-negative staphylococci (CNS) are important causes of infective endocarditis (IE), but their microbiological profiles are poorly described. We performed DNA target sequencing and susceptibility testing for 91 patients with definite CNS IE who were identified from the International Collaboration on Endocarditis-Microbiology, a large, multicenter, multinational consortium. A hierarchy of gene sequences demonstrated great genetic diversity within CNS from patients with definite endocarditis that represented diverse geographic regions. In particular, rpoB sequence data demonstrated unique genetic signatures with the potential to serve as an important tool for global surveillance.

Variations in the protective immune response against streptococcal superantigens in populations of different ethnicity.

Superantigens (SAgs) from group A streptococcus (GAS) are potent T cell mitogens, and have been suggested to play a role in severe streptococcal disease. Neutralizing antibodies protect against SAg-mediated disease and their levels should therefore be inversely related to severe streptococcal infection. Neutralizing anti-SAg titers in patients with severe GAS infection and patients without disease were compared in two separate groups. The first group comprised patients with invasive GAS disease from New Zealand European, Maori, and Pacific Island descent. The second group comprised Aboriginal Australian individuals with rheumatic heart disease and/or a past history of acute rheumatic fever. Patients sera were tested for their ability to neutralize T cell mitogenicity of recombinant streptococcal SAgs as a measure of functional SAg-neutralizing antibody concentration. In both studies, no inverse correlation was observed between disease and the level of serum SAg-neutralizing activity. Notably, much higher levels of natural immunity to all streptococcal SAgs were found in New Zealand Maori, New Zealand Pacific Island, and Aboriginal Australian individuals, suggesting a high degree of natural exposure and seroconversion in these groups compared to the New Zealand European cohort. Levels of serum antibodies against SAgs could not be used to predict disease susceptibility in groups with existing high levels of SAg-neutralizing antibodies.

Phenotypic and molecular characterization of community occurring, Western Samoan phage pattern methicillin-resistant Staphylococcus aureus.

In New Zealand, it is estimated that greater than half of the methicillin-resistant Staphylococcus aureus (MRSA) strains recovered from patients belong to what has been termed Western Samoan phage pattern types 1 and 2 (WSPP1, WSPP2). These strains differ from classical MRSA isolates in terms of their lack of multiresistance and community occurrence, suggesting that such strains possess properties and/or characteristics different from those of other MRSA. To address this hypothesis, 10 WSPP1 and WSPP2 isolates from Western Samoa, New Zealand and Australia were compared with common hospital MRSA isolates. All WSPP isolates were identical with regard to pulsed-field gel electrophoretic pattern of SmaI-digested DNA, coagulase gene restriction fragment length polymorphism pattern and localization of mecA to a 194 kb SmaI digestion fragment. The WSPP strains were no more resistant/sensitive to various environmental stresses (e.g. skin fatty acids, UV light, desiccation) compared with hospital epidemic MRSA strains, except for their higher tolerance to salt. In terms of virulence, the WSPP MRSA were quantitatively better at attaching to the epithelial cell line HEp2, were uniformly egg-yolk opacity factor negative and produced higher levels of haemolytic toxins compared with non-WSPP MRSA isolates.

Corynebacterium species isolated from patients with mastitis.

Corynebacteria were isolated from breast tissue, pus, or deep wound swabs of 24 women; the most common species isolated was the newly described Corynebacterium kroppenstedtii, followed by Corynebacterium amycolatum and Corynebacterium tuberculostearicum. Gram-positive bacilli were seen in samples sent for culture or in histological specimens for 12 women, and 9 of the 12 women from whom adequate histological specimens were obtained had conditions that met the criteria for granulomatous lobular mastitis, a chronic inflammatory disease of unknown etiology.