Dental Procedure Bacteremia and Antibiotic Prophylaxis

Abstract

Source: Lockhart PB, Brennan MT, Kent ML, et al. Impact of amoxicillin prophylaxis on the incidence, nature, and duration of bacteremia in children after intubation and dental procedures. Circulation. 2004;109:2878–2884.Investigators from Charlotte, NC, performed a double-blind, placebo-controlled, randomized study to ascertain the incidence, nature, and duration of bacteremia in children undergoing dental procedures and the impact of the American Heart Association’s (AHA) recommendations for antibiotic prophylaxis.1 Children with underlying medical conditions, allergy to penicillin, those who were assigned a high score for risk using American Society of Anesthesiologists guidelines, and those who needed antibiotic prophylaxis for an underlying medical condition were not eligible for the study. Children exposed to systemic antibiotics within the past 2 weeks and those <12 kg in weight were also excluded. One hundred children 1 to 8 years of age (mean age 3.5 years) undergoing operative dental procedures between March 1994 and June 2000 were included in the study. Fifty-one children were randomly assigned to receive amoxicillin (50 mg/kg) and 49 placebo, 1 hour prior to intubation. A total of 8 blood specimens (6 ml) for culture were drawn. Specimens 1–3 were taken 2 minutes after intubation, after performing a complete oral/dental examination and cleaning post-intubation, and 10 minutes post-intubation (this was considered the baseline culture prior to the dental extractions). Ninety seconds after the initiation of the first extraction, and after the completion of the final extraction, the fourth and fifth blood culture specimens, respectively, were drawn. Additional blood specimens were taken 15, 30, and 45 minutes after the final extraction. All blood cultures were incubated for 14 days using the BACTEC system. Duration of bacteremia was calculated only if the fourth and/or fifth blood cultures were positive, and these results were combined and were defined as the extraction incidence (EI) draw. Duration of bacteremia was calculated as the time between EI and last positive culture from specimen 6, 7, or 8.The overall incidence of bacteremia was 84% (43/51) in the placebo group compared to 33% (16/49) in the amoxicillin group (P<.0001). The peak incidence of bacteremia occurred 90 seconds after the completion of tooth extractions (culture #5), and was 76% in the placebo group compared to 6% in the amoxicillin group (P<.0001) (see Figure on page 43). The incidence of bacteremia was higher in the placebo group after intubation (18% versus 4%, P=.05), and showed a trend towards increased bacteremia after cleaning (20% versus 16%, P=.07). Only 1 child in the amoxicillin group had bacteremia at 15 minutes post-extraction, and none at 30 and 45 minutes, compared to 7 (18%), 6 (16%), and 5 (14%), respectively, in the placebo group. There was a statistically significant decrease in bacteremia incidence in the amoxicillin group at all blood culture times except the second culture. Logistic regression analysis showed that the incidence of bacteremia associated with extraction increased with the age of the child (P=.025) and the number of teeth extracted (P=.002). It also showed that the use of amoxicillin decreased the incidence of bacteremia associated with both extraction (P<.0001) and intubation (P=.03). Of the 152 positive cultures, 29 different oral bacteria were cultured and the majority (56%) were Gram-positive cocci. Viridans streptococci were the most common microorganisms isolated.The AHA currently recommends amoxicillin prophylaxis in children with risk factors for infectious endocarditis (IE).1 While the assumption that procedure-related, transient bacteremia causes a significant number of cases of IE appears intuitively correct, only studies in animals directly support this hypothesis.2 Retrospective and case-control studies in humans, primarily adults, have yielded conflicting results.3 Moreover, transient bacteremia has been documented following commonplace activities such as tooth brushing and flossing.4 Appropriate prospective, placebo-controlled study is obviously ethically and medico-legally untenable. Because of the significant morbidity and mortality of IE, however, recommendations for prophylaxis will continue to be made.5 Nine major revisions to the guidelines have appeared since they were first issued by the AHA in 1955, the latest in 1997. The above findings of a much higher incidence of bacteremia in children than previously reported, as well as bacteremia of longer duration in the placebo group of relatively healthy children, are of major concern. The fact that the most common organisms isolated were V streptococci, the organisms also most likely to cause endocarditis in children, provides support for the argument that prophylaxis and adherence to the AHA guidelines, whatever their iteration, are warranted.