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Experimental infective endocarditis

1979; Elsevier BV; Volume: 22; Issue: 3 Linguagem: Inglês

10.1016/0033-0620(79)90021-5

1873-1740

Lawrence R. Freedman, James A. Valone,

Bacterial Identification and Susceptibility Testing

I T WAS about 100 yr ago that bacteria were identified as the cause of infective endocarditis. Subsequently, there was a long period of clinical observation, during which time the natural history and secondary manifestations of the disease were defined. This process culminated in the 1940s and 1950s with the development of powerful antibiotics capable of curing the great majority of patients. There was then a delightful, “honeymoon” period during which a once uniformly fatal disease was brought to its knees by modern technology. There quickly followed, however, the phase in which we now find ourselves, where the continued technologic advances of science have provided new breeding grounds for the reemergence of infective endocarditis as a serious medical problem. Whereas underlying congenital or rheumatic heart disease still represent important risk factors for the development of infective endocarditis, chronic hemodialysis, intracardiac catheters. and prosthetic valve surgery, as well as narcotic addiction, are responsible for new susceptible populations. Clinical criteria have changed; Weinstein and Rubin have put it succintly, pointing out that if one were to use the diagnostic clinical criteria of 25-30 yr ago, one would not suspect the diagnosis in at least 90% of cases.’ The microbiologic features of the disease have also changed. It has been pointed out several times that today, in contrast to the preantibiotic era, viridans streptococci are much less often recovered than staphylococci and other microorganisms. The patterns are well illustrated in the figures taken from three published series. Table 1, series 1, is that of Mandell and Sande,’ series 2 that of Kenevan and Zinneman,’ and series 3 that of Falase et aL4 There is a progressive decrease in the importance of viridans streptococci, and the opposite trend is seen with the staphylococci. All three of these series were published within the past 7 yr, but from different parts of the world. Obviously, there are many factors that influence the prevalence of infecting microorganisms in addition to the presence or absence of antibiotics. In brief, infective endocarditis today, to an important degree, represents one of the elements of biologic fallout resulting from the pollution of technologic advance. To carry the analogy one step further, the impact of the social disruption that has accompanied technologic progress is seen in the frequency of infective endocarditis in drug addicts. In other words, endocarditis is still a serious medical problem. To the physician of today, it is not only the fascinating disease it always has been, but a new disease, which in today’s world is posing complex problems of prevention, diagnosis, and treatment. It is no wonder that there has long been a desire to reproduce infective endocarditis in animals, since there are many questions to answer. Although various models for producing endocarditis have been available for almost 100 yr, these older models were unsatisfactory from several points of view: difficulty in establishing infection, need to use large animals, inconsistency of infection, and the necessity to employ cardiac surgical procedures to establish the model.s.6