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This is a case report of septic arthritis of the knee due to Prevotella loescheii, in a patient with advanced arthrosis. Two weeks beforehand he had undergone a dental root extraction without antibiotic prophylaxis. His knee had become inflamed 48 hours after extraction and he was started on ibuprofen and steroid treatment (prescribed by his primary health care doctor). With a provisional diagnosis of septic arthritis, synovial fluid was taken for study. Antimicrobial therapy was commenced with amoxicillin/clavulanic acid and the patient progressed satisfactorily. Prevotella loescheii was identified by anaerobic culture. A site of origin for the infection was never found. Joint infection is generally secondary to haematogenous dissemination of bacteria from habitual sites such as odontogenic locations. We suggest that patients with inflammatory arthropathies should be considered as candidates for antibiotic prophylaxis in oral surgery and invasive dental procedures. We suggest, in these cases, the use of antibiotic with spectrum against aerobic and anaerobic bacteria.

Transient bacteraemia is a known risk factor following oral surgery and invasive dental procedures in patients with altered immune system response and those with a susceptible site of infection (patients with heart valve prostheses or recent joint replacements, etc.) The most commonly isolated aerobic bacteria in postoperative bacteraemia are Streptococcus Viridans. However, other periodontal pathogenic anaerobic bacteria are found in up to 64% in blood cultures (mixed bacteria or anaerobic bacteria alone). Dental pathogenic bacteria do not appear to be covered by standard amoxicillin or clindamycin prophylactic regimens. This is partly due to the fact that these anaerobic bacteria often produce beta lactamase and also in view of results of antimicrobial sensitivity tests observed in recent studies. A personal history of exposure to dental pathogenic bacteria may have an impact on the patient s global health, not only because of classical local or systemic infectious complications, but also because dental pathogenic bacteria have been found in atheromatous plaques in coronary and carotid arteries. This finding, along with epidemiological data, suggests that such bacteria may contribute to the progression of vascular arteriosclerotic lesions and the occurrence of cardiovascular and/or cerebrovascular accidents, although the pathogenic mechanisms involved are not yet well known. Taking these facts into consideration, and in view of antimicrobial sensitivity data available at present, we believe that the use of amoxicillin/clavulanic acid is the most appropriate option for prophylaxis of all infectious risks associated with bacteraemia of oral origin, due to its broader cover of dental pathogenic bacteria and its pharmacokinetic profile.

The infection of the oral cavity is a common public health problem and constant cause for antibiotic prescription, with 10% of antibiotics used to treat this problem. However, few studies have so far aimed to determine its incidence. Added to this, its relationship with certain sytemic diseases (cardiac, endocrine, etc) confers this pathology vital importance. In spite of the frequency and importance of odontogenic infection, the current dispersion in criteria regarding key aspects in classification, terminology and therapeutic recommendations is noticeable. The main objective of this document, compiled as a consensus statement by specialists in microbiology and odontology, is to establish useful recommendations for all of those involved in the clinical management of this pathology. Special attention has been placed on the rise in bacterial resistance observed over the last years, specifically the proliferation of betalactamase producing strains. Another important factor causing the resistance to appear is lack of therapeutic compliance, specially what regards dosage and treatment duration. Therefore, this pathology constitutes a complex problem which requires the instauration of broad spectrum antimicrobials, well tolerated and a convenient posology so that patients receive the adequate dose over the necessary period. High doses of amoxicillin/clavulanate (2000 mg/125 mg) have showed good results and power to overcome resistance. Other agents such as metronidazole and clindamycin, followed by de claritromycin and azithromycin have also proved to be active against most of microorganisms responsible for odontogenic infection.

Most infections of the oral cavity are primary, odontogenic infections, with dental caries, gingivitis, and periodontitis the most common. Treating these infections will encompass odontologic, antimicrobial, surgical or combined treatment. Antimicrobial treatment includes the use of betalactams, macrolydes, tetracyclins, metronidazole, clindamycin, or combined treatment. The most commonly used ones are administered orally. PK/ PD parameters predict THE clinical and microbiological efficacy of the antibiotic. The three indices that are generally used to measure clinical efficacy are: T >MIC (time during which the concentration is above the minimum inhibitory concentration), Cmax/ MIC (ratio between peak concentration and the minimum inhibitory concentration) and AUC/ MIC (ratio between the area under the curve and the minimum inhibitory concentration). Amoxicillin/ clavulanic acid is one of the antibiotics recommended for the treatment of odontogenic infections due to its wide spectrum, low incidence of resistance, pharmacokinetic profile, tolerance and dosage.