**7. Detractors of antibiotic prophylaxis**

In view of the lack of scientific evidence on the prophylactic efficacy of the antibiotics for the prevention of IE, the British health authorities have focused their attention on the principle problems of the indiscriminate administration of antibiotics [6]:


of oral bacteraemia during dental procedures [15, 28, 29]. Some authors have proposed moxifloxacin as an alternative to amoxicillin, given its efficacy in experimental endocarditis [30] and in the prevention of bacteraemia following dental procedures in humans [15]. However, endocarditis expert committees appear to be ignoring this antibiotic at the present

*S. aureus* is now the most common pathogen in IE. This circumstance could justify the use of amoxicillin in association with a β-lactamase inhibitor, such as clavulanate, to broaden the bactericidal spectrum of antibiotic prophylaxis against IE. A recent study suggests that intravenous amoxicillin/clavulanate could be effective in the prevention of oral bacteraemia, virtually eliminating post-procedure inocula [29]. This observation opens the door to further research into the efficacy of oral amoxicillin/clavulanate in the prevention of bacteraemia. In any case, given its unusual demonstrated effectiveness in the elimination of oral bacteraemia, the intravenous prophylactic regimen of amoxicillin/clavulanate could be a high-efficacy alternative for patients with cardiac risk factors and severe systemic alterations, such as

Up to 2008, epidemiological studies did not support the hypothesis for the use of prophylactic antibiotics for medical procedures as a preventive method against IE. Case-control studies indicated that most IE events occurred independently of medical interventions and of the administration of antibiotic prophylaxis. A further argument was that despite the universal application of antibiotic prophylaxis, the incidence of IE and its associated mortality had not

In 2008, cessation of the NICE recommendation for antibiotic prophylaxis introduced a new epidemiological context into the study of IE, and analysis will serve to establish reliable conclusions in its area of influence. Implementation of the NICE guideline in England provides an opportunity for retrospective studies to investigate the comparative effect of antibiotic

Initially, the data suggest a significant increase in the incidence of IE after implantation of the NICE guideline, rising above the projected historical trend. This observation could lead to the hypothesis that the increased incidence of IE could be related to medical procedures in susceptible individuals performed without appropriate antibiotic cover. With regard to the dental procedures, we should observe an increase in the incidence of IE caused by oral viridans group streptococci but, at the present time, no data are available on pathogen-specific causal

In view of the lack of scientific evidence on the prophylactic efficacy of the antibiotics for the prevention of IE, the British health authorities have focused their attention on the principle

immune compromise, who require curative interventional dental treatment.

prophylaxis versus no prophylaxis on the incidence of IE.

**7. Detractors of antibiotic prophylaxis**

problems of the indiscriminate administration of antibiotics [6]:

time.

**6.3. Epidemiological studies**

28 Contemporary Challenges in Endocarditis

varied over decades [5].

microorganisms [30].

However, a recent study on the incidence and nature of adverse reactions to antibiotics prescribed for endocarditis prophylaxis in England from 2004 estimates that reported adverse drug reaction rates from amoxicillin prescribed as antibiotic prophylaxis are low, without a single fatal reaction for nearly 3 million prescriptions [31].

The emergence of antibiotic resistance is a serious public health problem, but prophylactic antibiotic regimens for IE would only have a very limited effect as evidence shows that bacteria acquire resistance to antibiotics only after the administration of several consecutive doses.

With regard to the cost to the national health systems of the systematic administration of prophylaxis, cost-efficacy analyses of antibiotic prophylaxis for at-risk patients undergoing dental treatment provided contradictory results. In some countries, such as the USA, it has been estimated that prophylaxis constitutes a considerable expense, [32] but their results cannot be extrapolated to other countries in which the administration of prophylactic antibiotics to high-risk patients only represents a very small percentage of all the antibiotics that dentists prescribe.

Research into the control of bacteraemia shows that the administration of amoxicillin significantly reduces bacteraemia of oral origin, though it does not completely eliminate the possibility that this could occur. Alternative antibiotics such as clindamycin have shown poor results in the reduction of bacteraemia after dental interventions, leading us to deduce that the efficacy of prophylactic antibiotics in the prevention of IE in high-risk patients undergoing dental manipulations is limited.
