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Bacteremia and Endocarditis

Bacteremia and Endocarditis. Monday, September 15, 2008. 2 sets, >15 minutes apart and preferable 2 sites Clearly document source Now continuous monitoring No entry of bacteria for monitoring

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Bacteremia and Endocarditis

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  1. Bacteremia and Endocarditis Monday, September 15, 2008

  2. 2 sets, >15 minutes apart and preferable 2 sites Clearly document source Now continuous monitoring No entry of bacteria for monitoring lysis-centrifugation system (Isolator) used for either routine bacteria, fungi, mycobacteria, or fastidious organisms such as Bartonella or Brucella Labor intensive More contamination Technique 70% alcohol, followed by tincture of iodine (1 minute) or povidone iodine (2 minutes). septum of the culture bottle or tube need only be wiped with 70% alcohol transported to the lab promptly volume of blood cultured and number of sets drawn are important current recommendations for adults are to draw at least two separate blood cultures totaling 30 to 40 ml of blood. Separate venipunctures-to help interpret cultures that contain skin flora Blood Cultures

  3. Classification of Bacteremia • Community-acquired • Nosocomial • Healthcare-associated Bacteremia • indwelling catheters • HD • receiving other outpatient therapy • Wound care • nursing home residents

  4. Friedman: Ann Intern Med, Volume 137(10).November 19, 2002.791-797

  5. Martin: N Engl J Med, Volume 348(16).April 17, 2003.1546-1554

  6. Martin: N Engl J Med, Volume 348(16).April 17, 2003.1546-1554

  7. Staph aureus bacteremia • up to 13% of cases of S. aureus nosocomial or community-acquired bacteremia may become complicated with infective endocarditis, even in the absence of cardiac risk factors (some studies suggest even higher risk), regardless of other identifiable source

  8. “contaminant” vs transient • Single set positive for skin flora, especially if polymicrobial, very likely to be contaminant • If suspect contaminant, before starting an antibiotic (if you must), repeat BCx • Exceptions occur • Prosthesis or port infection • Pathogens LIKELY TO BE skin organisms • Transient (true) bacteremia also occurs • Toothbrushing • ERCP • Abscess drainage

  9. Infectious Endocarditis (IE) • Traditional risk factor of RHD decreasing, newer factors increasing • Emergence of enterococci and Staph, particularly MRSA and VRE, also VISA and VRSA • Viridans Strep now emerging MDR strains • Subtypes • native value IE • RHD • MVP (10-100 fold increased risk if regurgitant) • Degenerative/inherited valve disorders • prosthetic valve IE • Early (Staph epi, Staph aureus) • Late (Strep, HACEK) • IE in intravenous drug users • Healthcare-associated IE • nosocomial IE

  10. Microbiologic Etiology in 1779 Patients With Definite Endocarditis From:   Fowler: JAMA, Volume 293(24).June 22/29, 2005.3012–3021

  11. Trends in Age- and Sex-Adjusted Incidence Rates of Infective Endocarditis Caused by Staphylococcus aureus and Viridans Group Streptococci From 1970 to 2000 in Olmsted County, Minnesota From:   Tleyjeh: JAMA, Volume 293(24).June 22/29, 2005.3022–3028

  12. IDU-associated IE • median age 30 and 40 yrs • up to 40% of cases of IE in San Francisco • tricuspid valve > 50% of cases, aortic in 25%, mitral in 20%, mixed right- and left-sided IE unusual. • injections of impure drugs and particulates might produce microtrauma to the tricuspid leaflets, facilitating microbial colonization • 20–40% of IDU with IE have pre-existing cardiac lesions • Bacteria often originate from the skin • streptococci and others also seen • Pseudomonas aeruginosa and fungi may produce severe IE. • mortality of IE higher in patients who have AIDS

  13. Nosocomial IE • The incidence is increasing. • Many patients have other debilitating underlying • < 50% had obvious cardiac predisposing factors • In most circumstances a potential source of bacteremia could be identified, (lines, procedures) • staphylococci and enterococci most common • other organisms-Gram-negative bacteria and fungi. • Right-sided IE is increasingly recognized in association with central venous lines, pulmonary artery catheters and pacemakers. • procedures that produce transient bacteremia represent risk in hospitalized patients, especially when the circulating organism is S. aureus. • mortality of nosocomial IE is greater than 50%.

  14. Culture-negative IE • HACEK • Haemophilus spp. • Actinobacillus actinomycetemcomitans • Cardiobacterium hominis • Eikenella corrodens • Kingella kingae • Nutritionally-deficient Strep spp. • Fastidious GNR

  15. Culture-negative IE • Coxiella burnetii (Q fever) • Brucella • Bartonella quintana • Chlamydia • Tropheryma whippelii

  16. Pathogenesis • Basic lesion is endothelial damage • IE pathogens possess surface ligands that mediate attachment to extracellular matrix proteins of the host (MSCRAMMs) • direct invasion of endothelial cells may also occur • Transient bacteremias occur during chewing, toothbrushing and other normal activities, and from more invasive procedures

  17. Pathogenesis

  18. Microscopic appearance of a vegetation from a patient suffering mitral valve infective endocarditis due toStreptococcus sanguis. The purple area represents clusters of streptococci packed within a fibrin-platelet meshwork. Professional phagocytes are essentially absent from the lesion.

  19. IE Prophylaxis • Goals: • identification of patients at risk; • determination of the procedures or circumstances that may result in bacteremias; • choice of an appropriate antimicrobial regimen; and • balancing of the known risks against the possible benefits of intervention. • No controlled studies • Regimens used in humans are based upon their proven efficacy in animal models of IE • successful prophylaxis does not require bactericidal antibiotics • Antiseptic mouth rinses applied immediately prior to dental procedures may reduce the incidence or magnitude of bacteremia • Cover most probable pathogens circulating in the blood during a given procedure • oropharyngeal manipulation-streptococci • gastrointestinal or urogenital manipulations, it should be aimed at enterococci (plus results of a preprocedure urine culture) • skin or other infected lesions-staphylococci • If already on antibiotics, choose another class.

  20. SBE prophylaxis Recommendations by the American Heart Association

  21. Negligible risk • These cardiac conditions are felt not to require prophylaxis.  • Isolated ostium secundum ASD and surgically repaired ASD, VSD and PDA (beyond 6 months and without sequelae).  • Mitral valve prolapse without mitral regurgitation and without thickened leaflets.  • Innocent or physiologic murmurs (echo required in the adult population to rule out valvular lesion).  • Cardiac pacemakers and defibrillators.  • History of isolated bypass surgery, history of Kawasaki disease without valvular dysfunction and history of rheumatic fever without valvular dysfunction. 

  22. High risk • These conditions are:  • All prosthetic heart valves (including bioprostheses and homografts).  • Any history of previous bacterial endocarditis.  • Complex cyanotic congenital heart disease and surgically constructed systemic pulmonary shunts. 

  23. Moderate risk Most cardiac conditions requiring prophylaxis will fall into this category.  Congenital cardiac malformations, not falling into the high or negligible risk categories (such as PDA, VSD, ostium primum ASD, bicuspid aortic valve and coarctation).  Acquired valvular heart disease (such as rheumatic heart disease, valvular stenosis and regurgitation).  MVP with regurgitation and/or myxomatous leaflets.  Hypertrophic cardiomyopathy.

  24. What’s different? The lower dose of amoxicillin and the lack of a second dose 6 hours post-procedure for oral regimens is a substantial change from the previous recommendations. The lack of an erythromycin regimen for oral procedures is another substantial change. 

  25. Diagnosis • Duke criteria • Classic exam/lab findings • Osler nodes • Splenomegaly • Janeway lesions • Microscopic hematuria • Elevated ESR and CRP • Septic pulmonary emboli (right) • Classic findings may be absent • Repeating TEE 7 to 10 days after an initial "negative" result may be advisable • Posttreatment echocardiography is recommended

  26. Peripheral Stigmata of IE • Osler node=small, raised, tender cutaneous lesion, usually on the pads of fingers or toes (vasculitic) • Janeway lesion=flat, painless small hemorrhages with a slightly nodular appearance that occur on the palms and soles (septic emboli) • Splinter hemorrhages • Petechiae • Roth spots=hemorrhage in the retina with a white center

  27. Janeway lesions

  28. Roth spot

  29. Surgery • Indication • Severe CHF (reduced mortality with surgery) • Persistent bacteremia • Certain pathogens (fungal, GNR) • Embolic events • Large vegetation on mitral valve highest risk • Valve abscess/dehiscence • Timing • 7-fold higher risk of recurrent IE if valve replaced during active infection

  30. Treatment • If using synergistic agents give them together • Day 1 is first day documented negative blood cultures • postoperative treatment regimen should be one that is recommended for prosthetic valve treatment rather than one that is recommended for native valve treatment • Start over if cultures positive

  31. community-acquired native valve endocarditis in patients who are not intravenous drug users (IDUs). -hemolytic S sanguis, S oralis (mitis), S salivarius, S mutans, and Gemella morbillorum (formerly called S morbillorum). S anginosus group (S intermedius, anginosus, and constellatus) aka S milleri group tends to form abscesses and cause hematogenously disseminated infection (eg, myocardial and visceral abscesses, septic arthritis, vertebral osteomyelitis). S intermedius usually is sensitive to penicillin, but some strains may exhibit variable penicillin resistance. Abiotrophia defectiva and Granulicatella species (G elegans, G adiacens, G paraadiacens, and G balaenopterae; formerly known as nutritionally variant streptococci), have nutritional deficiencies that hinder their growth Gemella (morbillorum, bergeriae, sanguinis, and hemolysans) share some physiological characteristics with nutritionally variant streptococci should be treated with more aggressive combination therapy S bovis expresses the group D antigen, but it can be distinguished from group D Enterococcus by appropriate biochemical tests. should undergo colonoscopy Viridans Strep

  32. Treatment • Native valve, highly susceptible viridans Strep or Strep bovis (MIC <.12) • Aq Pen G x 4 wks • Rocephin x 4 wks • Aq Pen G + gent x 2 wks (synergy) • Rocephin + gent x 2 wks • Vanc x 4 wks • Viridans Group Streptococci and S bovis With Penicillin MIC >0.12 to 0.5 µg/ml • Aq pen or Rocephin x 4 wks + gent 1st 2 wks (single daily dose) • vancomycin

  33. Treatment • A defectiva, Granulicatella species, and Gemella species and a microorganism with an MIC to penicillin >0.5 µg/mL should be treated with a regimen that is recommended for enterococcal endocarditis • prosthetic valves should receive 6 weeks of therapy with penicillin or ceftriaxone with or without gentamicin for the first 2 weeks • S pneumoniae, S pyogenes, and Groups B, C, and G Streptococci • highly penicillin-susceptible S pneumoniae should receive 4 weeks of antimicrobial therapy with penicillin, cefazolin, or ceftriaxone • High-dose penicillin or a third-generation cephalosporin can be used in patients with penicillin-resistant infection and without meningitis • If the isolate is resistant (MIC 2 µg/mL) to cefotaxime, then the addition of vancomycin and rifampin should be considered. • Consider gentamicin for at least the first 2 weeks of a 4- to 6-week course of antimicrobial therapy for group B, C, and G strep (relatively pen res) • Aq pen G for Gp A

  34. Usually associated with PVE Occasionally native valve, usually damaged More indolent than Staph aureus Staph lugdinensis more virulent Coagulase-negative Staph (CoNS)

  35. Nosocomial bacteremia previously thought to be lower risk for endocarditis health care–associated infection was the single most common form of S aureus IE health care–associated IE is distinguished by a relative infrequency of classic clinical stigmata of IE S aureus bacteremia associated with health care has increased among hospitalized patients and among those receiving outpatient medical therapy MRSA in both hospital and community increased dramatically implanted medical devices prosthetic heart valves grafts hemodialysis catheters pacemakers Staph aureus endocarditis

  36. Endocarditis • Factors associated with Staph aureus SBE: • Native valve • Hemodialysis • Invasive procedures • Other chronic disease • Multiple pulmonary emboli • Intravascular device source • Tricuspid • Healthcare-associated • IDU-associated • Persistent bacteremia, emboli requiring surgery • Complications including stroke, other emboli, death • Factors associated with non-Staph aureus SBE • Aortic valve • Prosthetic valve • Congenital heart disease • Dental work • Symptoms >1 month International Collaboration on Endocarditis-Prospective Cohort Study from June 2000 to December 2003.

  37. Figure. In-Hospital Mortality Rates Among Patients With Health Care–Associated Staphylococcus aureus Endocarditis. Includes both nosocomial and nonnosocomial health care–associated infections, community-acquired injection drug use–associated S aureus endocarditis, and community-acquired noninjection drug use–associated S aureus endocarditis by geographic region. From:   Fowler: JAMA, Volume 293(24).June 22/29, 2005.3012–3021

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