En todos los estudios epidemiológicos de la EI, la proporción varones:mujeres es ≥ 2:1, aunque esta mayor proporción de varones no se comprende del todo. Es más, las pacientes pueden tener un pronóstico peor y someterse a cirugía valvular con menor frecuencia que sus homólogos varones.
Con la aparición de microorganismos resistentes a diversos y novedosos antimicrobianos, el surgimiento de nuevos factores predisponentes, entre los que sobresalen la drogadicción endovenosa, las prótesis valvulares cardíacas u otros materiales extraños intracardíacos y el uso masivo de catéteres centrales, se han presentado nuevas formas de la enfermedad, con características propias que crean las bases para la clasificación actual de esta entidad clínica y se distinguen por su agente causal, evolución, pronóstico y enfoque terapéutico. 5
Hay que destacar que la bacteriemia no sólo ocurre después de los procedimientos invasivos, sino también como consecuencia de masticar y lavarse los dientes. Esta bacteriemia espontánea es de un grado bajo y de corta duración (1-100 ufc/ ml de sangre y menos de 10 min), pero su elevada incidencia explica el motivo por el que la mayor parte de los casos de EI no se relacionan con procedimientos invasivos26,36.
The top three risk factors for IE include, IVDA, prosthetic heart valves, and structural heart disease. IVDA – one large study of IVDAs found that the use of cocaine was associated with a higher risk of IE than other injectable drugs. The most significant risk factor for right-sided IE is IVDA, although left sided disease is quite common among IVDAs. The most common infecting organism is clearly S. aureus, particularly in right-sided infection. Prosthetic valve IE comprises a small proportion of all cases of IE and occurs in only 1% of all patients with artificial heart valves. The greatest risk is in the first year following valve replacement. Structural heart disease – approximately ¾ of all cases of IE occur in patients with preexisting structural heart abnormalities. The most common underlying heart abnormalities include mitral valve prolapse with mitral regurgitation and aortic stenosis. The most common congenital heart defects include Tetralogy of Fallot, bicuspid aortic valves, coarctation of the aorta, VSDs, and patent ductus arteriosus. In general, the higher the gradient of the valvular insufficiency, the higher the risk of IE. One of the greatest risk factors of all is a prior episode of IE. Some studies have documented recurrence as high as 9%.
Subungal hemorrhages that extend the entire length of the nail or are primarily located at the proximal end of the nail (near the cuticle) are like due to trauma.
La primera clasificación utilizada fue la de Von Reyn, la cual se basa en criterios estrictos bacteriológicos, datos clínicos y anatomopatológicos. Según esta, una EI es definitiva solo si se cuenta con la confirmación anatomopatológica, lo que ocurre en menos de un tercio de los casos. Dicha catalogación no toma en cuenta los hallazgos ecocardiográficos, no considera la drogadicción endovenosa como factor de riesgo y no reconoce algunos gérmenes típicos de EI (HACEK, Streptococcus agalactiae grupo B). Años más tarde se desarrolló una nueva clasificación en la Universidad de Duke, que incluye la ecocardiografía y también criterios mayores y menores. Von Reyn criteria – modified the above criteria to improve specificity and clinical utility. Duke Criteria – relies upon major and minor clinical and pathologic criteria to classify cases as definite, possible, and rejected
- Nuevos elementos incorporados recientemente para mejorar la eficiencia diagnóstica de estos criterios, así se han realizado estudios que incluyen algunos aspectos como esplenomegalia, elevación de los marcadores inflamatorios (proteína C-reactiva, eritrosedimentación), hematuria y la presencia de catéteres venosos centrales o periféricos;
If you suspect the pt has subacute IE or is not critically ill, then the three samples can be collected over 24-72 hours and antibiotics can be held until all three samples have been drawn. However, if the pt is acutely ill, critical, or unstable, the three cultures should be obtained over a 1 hour time span before beginning empiric therapy. There is no need to collect anaerobic blood cultures since virtually all cases of IE are caused by aerobic organisms. There is little additional diagnostic yield to collecting more than three blood cultures unless the pt was previously on antibiotics. In one study of 206 cases of IE, the initial blood culture was positive in 96% of streptococcal IE and one of the first two cultures were positive 98% of the time. For pt’s with IE cause by organisms other than strep, one of the first two blood culture was positive in 100% of the cases. The estimated diagnostic yield of a blood culture increases by about 3% per mL of blood cultured. One study found that the detection rate for bacteremia increased from 69% to 92% when at least 5mL of blood were used for culture. The most common cause of negative cultures in patients with IE is prior antibiotic use.
CBC – Look for a normochromic normocytic anemia and/or a leukocytosis. ESR and CRP - Look for an elevated erythrocyte sedimentation rate and/or an elevated C-reactive protein which are present 90-100% of the time. RF - Occasionally there will be an elevated levels of Rheumetoid Factor, particularly in patients who have been infected for six weeks or more. (Minor Duke’s Criteria) UA - Urinalysis may reveal microscopic or gross hematuria, proteinuria, and pyuria. These findings along with a low serum complement level indicate a glomerulonephritis or “immunologic phenomena”. (Minor Duke’s Criteria)
TTE and TEE are complementary for evaluating cardiac hemodynamics and anatomy, but TEE has superior sensitivity, especially in detecting native valve vegetations, prosthetic valve vegetations, and local extension of infection. However, it is significantly more expensive and invasive. If there is any suspicion of IE, get a TTE. If there is staph or fungal bacteremia, a TEE should probably be obtained. If there is a high clinical suspicion for IE and the TTE is negative, you should proceed to a TEE. If there is a concern for intracardiac complications, a TEE is warranted. It’s important to remember that the negative predictive value of a TEE is between 96-98%, meaning that a TEE cannot definitively rule out endocarditis. If the initial TEE is negative in a patient with a high clinical suspicion for IE, a repeat examiniation should be done if the pt does not improve.
Multiple studies have validated the Duke criteria. When applied and reapplied over the entire evaluation, these criteria are sensitive and specific and very rarely erroneously reject a true endocarditis.
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