Infective endocarditis in the 1980s. Part 1. Aetiology and diagnosis

Endocarditis caused by Abiotrophia defectiva in children

Abiotrophia defectiva, formerly designated as the member of nutritionally variant streptococci, is a part of normal oral flora and may be a cause of culture-negative endocarditis. We report a case of infective endocarditis caused by A. defectiva involving the mitral valve in a 12-year-old girl. She received antibiotic treatment for 8 weeks and was symptom-free 6 months after discharge. We also reviewed the pediatric cases of nutritionally variant streptococcal endocarditis published in the English literature since 1971.

Oral microflora as a cause of endocarditis and other distant site infections

Bacteremia originating from the oral cavity is common, but the role of bacteremia in the genesis of infective endocarditis and other distant site infections is unclear. Only a small percentage of oral flora have been associated with distant site infection. Important issues remain unresolved concerning the identification of patients at risk, the relative risk from invasive dental procedures versus naturally occurring bacteremia, and the impact of prophylactic antibiotics on the incidence, nature, magnitude, and duration of bacteremia from the oral cavity. This article addresses the controversies in infection management in patients at risk for distant site infection.

Bacteraemia caused by periodontal probing

Bacteraemia of oral origin may result in infective endocarditis in susceptible individuals. The aim of this pilot study was to investigate the occurrence of bacteraemia due to periodontal probing. Thirty patients (15 male, 15 female; mean age 42.7 years) with untreated periodontitis were investigated. All were free of significant medical disorders and none had taken antibiotics in the previous month. Prior to and immediately following periodontal probing, 20 mL of venous blood were obtained from each patient and inoculated into aerobic and anaerobic blood culture bottles and incubated. Negative bottles were monitored continuously for three weeks before being discarded. Periodontal probing consisted of measuring pockets at six points around each tooth and recording the presence or absence of bleeding. A positive bacteraemia was recorded for three of the patients prior to probing. One patient exhibited Prevotella species whilst two exhibited skin commensals. Following probing, 13 patients (43 per cent) exhibited bacteraemia of oral origin. Viridans streptococci were the most common isolates (45 per cent). No significant correlations were found between bacteraemia and the severity of periodontitis or extent of bleeding on probing. The results indicate that periodontal probing can cause bacteraemia in patients with periodontitis. It would be advisable for patients considered at risk of developing infective endocarditis to receive antibiotic prophylaxis for periodontal probing if they have radiographic evidence of periodontitis.

Modulation of glycosidase and protease activities by chemostat growth conditions in an endocarditis strain of Streptococcus sanguis

The effects of growth conditions on the properties of the endocarditis-producing oral bacterium Streptococcus sanguis FSS2 were studied. This strain produces a variety of proteases and glycosidases, including a thrombin-like activity that is a potential virulence factor for endocarditis. Cultures were grown with limiting glucose or galactose in chemostats over a range of dilution rates and pH levels, and the following activities were measured at pH 7.5: thrombin-like, Hageman factor-like, N-acetyl-beta-D-galactosaminidase, beta-D-glucosidase, and beta-D-galactosidase. At growth pH 6.5, specific activities generally decreased as the dilution rate increased from 0.05 to 0.40 h(-1). At a dilution rate of 0.1 h(-1), specific activities generally were highest at growth pH 6.5 and lower and approximately equal at growth pH 5.5 and 7.5. The major exception was the thrombin-like activity, for which the specific activity at growth pH 7.5 was approximately 5-fold higher than at growth pH 5.5. Hageman factor-like activity was apparently glucose catabolite repressible, as its activity was 3-fold higher in galactose cultures. The measured activities changed as functions of growth conditions and thus were modulated by environment. Environmental regulation of thrombin-like activity by pH is consistent with an activity that is less important on tooth surfaces than in tissues.

Surgical management of infective endocarditis in children

Infective endocarditis occurs infrequently in the general pediatric population, occurring mostly in patients with congenital heart disease. This study reviews our surgical experience with infective endocarditis based on a policy of aggressive intervention, conservative operative debridement, and creative reconstruction options using pericardium and prosthetic heart valves. From 1982 to 1989, 16 patients, 3 weeks to 16 years of age, underwent 19 intracardiac operations for infective endocarditis therapy at Kosair Children's Hospital. Eight (42%) were for resection of vegetations alone; an additional 11 operations (58%) involved more extensive debridements requiring either valve replacement or valvuloplasty using pericardium for exclusion of an abscess cavity, closure of a fistula, or for valve repair. Operative mortality was 25% (4 patients) and related to preoperative disease severity. There was one late death. Offending organisms included Staphylococcus species (31%), Haemophilus influenzae (13%), pneumococcus (5%), gram-negative organisms (13%), and Candida (13%); no organism grew on culture in 25%. We conclude that aggressive surgical exploration in patients with infective endocarditis is indicated and often requires resection of vegetations alone. More extensive procedures should preserve as much valvular tissue as possible. Pericardium is useful for reconstruction after debridement.

The pediatrician's involvement in prevention and treatment of oral disease in medically compromised children

Significant oral health problems are associated with medical, physical, or mental disorders that occur in children. The pediatrician has the opportunity through early intervention to set the tone for a health care practice that will improve the quality of life for many disadvantaged children. When the pediatrician and pediatric dentist work hand in hand, the children can often expect a happy, healthy future.

The role of oral bacteria in the pathogenesis of infective endocarditis

Various micro-organisms have been implicated as causative agents for bacterial endocarditis, including lactobacilli and in particular the viridans streptococci which are more commonly associated with dental caries. Of these, the most frequently isolated one has the descriptive name Streptococcus sanguis. The disease is characterized by growth of micro-organisms within a platelet-fibrin thrombus protruding from a valve leaflet. An understanding of the pathogenesis involves knowledge of the mechanisms of conversion of the normal vascular surface to a thrombogenic one and the adhesion of micro-organisms to such surfaces. Model systems to study this interaction include experimental animals, mammalian epithelial cells and platelets, and proteins such as fibronectin and fibrinogen. Microbial protein surface components (adhesins) and lipoteichoic acid have also been implicated. Capsular polysaccharides may be involved, but the role of dextrans formed from sucrose has been over-emphasized as the polymers are not formed in situ. Antibiotic prophylaxis for patients at risk is based on bacteriostatic or bactericidal action. However, bacterial cell surface components involved in adhesion may also be affected, and knowledge of such reactions could provide a more rational basis for antibiotic prophylaxis.

A case of polymicrobial infective endocarditis involving Neisseria mucosa occurring in an intravenous drug abuser

The incidence of polymicrobial endocarditis has increased markedly in recent years, in association with the increasing level of abuse of intravenous drugs. Neisseria mucosa, an upper respiratory tract commensal, is a rare cause of infective endocarditis. We report the first case of polymicrobial infective endocarditis involving Neisseria mucosa occurring in an intravenous drug abuser.