Determination of the antimicrobial activity of 29 clinically important compounds tested against fastidious HACEK group organisms

HACEK group organisms are very fastidious organisms (Haemophilus spp Actino bacillus actinomycetemcomitans, Cardiobacterium hominus, Eikenella corroden s, Kingella spp.) that can produce serious invasive infections such as endo carditis. Problems with susceptibility testing methods and their rarity of isolation limit available information of therapeutic choices, particularly among newer antimicrobial agents. Forty-two HACEK strains were tested by th e Etest (AB BIODISK, Solna, Sweden) method against 29 anti microbial agents . Nearly all compounds exhibited activity with best potency observed among the tested beta-lactamase inhibitor combinations, "third- or fourth-generat ion" cephems, meropenem, fluoroquinolones, and rifampin. Numerous therapeut ic options appear possible for initial parenteral treatment followed by ora l "step-down" or switch therapy. Each case of HACEK infection therapy shoul d be gained by accurate susceptibility tests, for which the Etest seems pre ferred for these fastidious species. (C) 1999 Elsevier Science Inc.