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Uso Del Strep A En Dx De Faringoamigdalitis Aguda
 

Uso Del Strep A En Dx De Faringoamigdalitis Aguda

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    Uso Del Strep A En Dx De Faringoamigdalitis Aguda Uso Del Strep A En Dx De Faringoamigdalitis Aguda Presentation Transcript

    • Utilidad del test de diagnóstico rápido en faringoamigdalitis en las consultas de atencion primaria Marta Ocampo Fontangordo R IV MFyC - CS Monteporreiro 06 Junio 2008
    • Faringoamigdalitis
      • Uno de los procesos más frecuentes en AP
      • Variable según edad, etiología y tipo clínico.
      • Origen vírico : 70% de las ocasiones
      • Streptococo del grupo A se aísla en 10-20% de casos
      • En la práctica médica preocupa especialmente la etiología por S. pyogenes , por lo que el diagnóstico de rutina se encamina a confirmar o descartar el citado microorganismo.
      • El tratamiento antimicrobiano debe hacerse solo bajo sospechas fundadas de etiología bacteriana.
      • El tratamiento con penicilina sigue siendo el de elección en los procesos por S. pyogenes.
    • Epidemiología
      • España:
        • 4 millones consultas/años (20% de las consultas pediátricas)
        • Calculan 16 millones de casos anuales
        • De ellos 50 mil por Streptococcus pyogenes (0.31%/anual)
      • 3º cuadro respiratorio (resfriado común>traqueobronquitis aguda)
      • 15- 20% de todos los casos Infecciones respiratorias
      • 36-55%% de todas las prescripciones de antibióticos
        • MF sospechan una etiología bacteriana en el 60% de los casos
        • Administran antibióticos en el 85% de los enfermos (98% en pultácea)
      • Edad mayor incidencia: 3 y 15 años (sin predilección sexos)
      • Adulto causa frecuente de consulta absentismo laboral (hasta 6,5 días IT)
      • Meses fríos del año
        • Rhinovirus y otros virus respiratorios: finalde la primavera
        • Adenovirus: Principio del verano
        • Streptocócicas: invierno y principiosde primavera
    • Faringoamigdalitis
      • Faringitis agudas inespecíficas
        • Catarrales ,muy eritematosas, "rojas “
        • Eritemato-supurativas o " blancas “
      • Faringitis agudas específicas (manifestaciones faríngeas de infecciones Sistémicas)
        • Diftérica por Corynebacterium diphteriae
        • Fuso-espirilar de Plaut-Vincent por Fusobacterium necrophorum
        • Neisseria gonorrhoeae
        • Tularemia por Fran cisella tularensis
        • Herpangina por los virus Cosxackie A y V. Echo
        • Herpética: virus del Herpes simple o V-Z
        • Mononucleosis infecciosa por EBV
        • Candidiasis faríngea
      • Faringitis crónica (no infecciosas)
    • Faringoamigdalitis. Etiología Etiología Observaciones Vírica (60-80%) Rhinovirus (20%) Coronavirus (5%) Adenovirus (5%) Herpes simplex 1 y 2 (2-4%) Virus parainfluenza. Virus Influenza A y B (2%) Virus Cosackie A (< 1%) Virus Epstein-Barr, Citomegalovirus (< 1%) VIH Streptococcus grupoC y G Algunos casos de adultos Streptococcus Beta-hemolítico del grupo A ó pyogenes (5.10%)
      • < 3 años: raro
      • 3-5 años: poco frecuente
      • 5-15: alta incidencia (30-55%)
      • 20% de niños de 5-10 años son portadores sanos
      • Adultos: 5-23% de aislamientos
      Mycoplasma pneumoniae adolescentes y adultos jóvenes Anaerobios < 1% Chlamidia pneumoniae C. trachomatis No recurrencias
    • Clínica Invierno-primavera Variable ESTACIONAL Brusco Gradual INICIO Fiebre elevada Odinofagia importante Fiebre leve Odinofagia leve SÍNTOMAS DURACIÓN: Curso breve entre 3-5 días. Amígdalas y ganglios linfáticos pueden tardar semanas en recuperarse. Dolorosas. Aumento de tamaño Múltiples y pequeñas o ausentes ADENOPATÍAS Inflamación importante Exudado (70%) Eritematosa Exudado (65%) FARINGE Cefalea, dolor abdominal, naúseas, vómitos, exantema Conjuntivitis, rinitis, tos, mialgias, diarrea OTROS SÍNTOMAS 5-15 años < 2 años EDAD BACTERIANA VÍRICA
    • Diagnóstico etiológico clínico
      • Hasta un 30% de las faringitis de causa bacteriana cursa sin exudado amigdalar,
      • Un 65% de los casos de origen viral está presente el exudado
      Criterios de CENTOR-McISAAC Cultivo y Test antigénico rápido
    • Faringoamigdalitis. Criterios Centor (Grado recomendación B) Validado (McIsaac) para su utilización en niños y adultos Criterios Centor Puntos Temperatura > 38º 1 Exudado amigdalar 1 Adenopatías anteriores dolorosas e inflamados 1 Ausencia de tos 1 Edad (McISAAC) 3-14 años 15-44 años 45 años o más 1 0 -1
    • Faringoamigdalitis. Recomendación de las guías McIsaac WJ. CMAJ. 2000;163:811-5. Puntuación total Riesgo de infección estreptocócica Estrategia sugerida 0 1 1 – 2,5% 5 – 10% No test adicional ni ATB 2 3 11 – 17% 28 – 35% Cultivo o test antigénico y ATB si positividad ≥ 4 51 – 53% Tratamiento ATB empírico
    • Cultivo faríngeo
      • Patrón oro para el diagnóstico. Correctamente realizado (frotando la superficie de ambas amigdalas o las fosas amigdalares y la faringe posterior)
      • Tiene una sensibilidad superior al 90% para detectar S. pyogenes y un resultado negativo prácticamente descarta la implicación de esta bacteria.
      • Inconveniente:
        • La información se demora 48 horas
        • Prevalencia de portadores asintomáticos alto en niños. no permite distinguir entre infección aguda y estado de portador
    • Test antigénico rápido
      • Se completa en 5 minutos
      • Especificidad ≥ 95%
      • sensibilidad 80-96%
      • Adultos, un test rápido negativo se considera evidencia suficiente contra la implicación de S. pyogenes (baja prevalencia de este agente)
      • Inconveniente:
        • No distingue entre infección aguda y estado de portador, por eso en niños < 15 años algunos autores recomiendan ante la negatividad practicar cultivo
    • Test antigénico rápido
    • Validez de la evaluación clínica y la prueba StrepA en pacientes con amigdalitis
      • Evaluación clínica:
        • Sensibilidad 49%
        • Especificidad 81%
        • Riesgo de un resultado falso:
          • - Falso negativo: 51%.
          • - Falso positivo: 19%.
      • Exact StrepA Dipstick
        • Sensibilidad 80-90%.
        • Especificidad 98%.
        • Riesgo de un resultado falso:
          • - Falso negativo: 5%.
          • - Falso positivo: 2%.
      Andersen et al . Potential of antigen detection tests. BMJ 1995 IDSA, ACP: no iniciar antibioterapia hasta confirmación microbiológica (cultivo o test de detección antigénica)
    • ¿ Necesidad de pruebas de diagnóstico rápido? 3% Criterios de Centor ≥ 2 + Test Antigénico rápido/Cultivo 44-60 % Tratamiento empírico con con puntuación ≥ 3 (sin pruebas) Uso innecesario de tratamiento antibiótico Situaciones clínico-diagnóstico
    • Faringoamidalitis. Estrategia diagnóstica-terapéutica
      • Los pocos pacientes con complicaciones pueden ser tratados cuando esto ocurra
      • Un retraso del tratamiento con ATB hasta 9 días sigue siendo eficaz en la prevención de la fiebre reumática
      • La efectividad del tratamiento ATB puede mejorar si lo utilizamos en pacientes con mayor riesgo de infección por S. pyógenes
        • Predicción clínica (Criterios Centor)
        • Test antigénico rápido
        • Cultivo de frotis faríngeo
      • ¿Son los Streptotest útiles para confirmar el diagnóstico de faringitis por Streptococo beta-hemolitico tipo A en la consulta de Atención Primaria?
      • ¿Permiten la toma efectiva de decisiones clínicas sin esperar al cultivo faringeo?
    • Recursos de ayuda para la toma de decisiones en el punto de atención Guías de Práctica Clínica (GPC) Informes de Agencia de Evaluación Revisiones Sistemáticas (RS) Revistas secundarías o de resúmenes Temas valorados críticamente-CAT Metabuscadores Otros documentos: Consensos, libros electrónicos, etc.
    • Fuentes consultadas
      • CKS- Clinical Knowledge del NHS Britanico
      • http://www.cks.library.nhs.uk/clinical_topics
      • National Guideline Clearinghouse http:// www.guideline.gov /
      • Guidelines Finder de la  National electronic Library for Health del NHS británico http:// www.library.nhs.uk / guidelinesfinder /
      • CMA Infobase http:// mdm.ca / cpgsnew / cpgs / index.asp
      • Otros
    • Sore throat - acute - Making a diagnosis. Streptococcal infection (last revised in April 2008)
      • Rapid antigen tests:
      • Rapid antigen tests detect the presence of group A streptococcal antigen on a throat swab and produce results within a few minutes. However, they have poor sensitivity and make little impact on prescribing decisions [ SIGN, 1999 ; Cooper et al, 2001 ].
      • Throat swabs:
      • Throat swabs cannot differentiate between infection and carriage, they have poor sensitivity , results take up to 48 hours to be reported, and the analysis is relatively expensive [ Little and Williamson, 1996 ; MeReC , 1999 ; SIGN, 1999 ].
      • The results of throat swabs vary according to technique, culture site, and culture conditions [ Cooper et al, 2001 ].
      • Group A beta-haemolytic streptococcus (GABHS) can be isolated from up to 30% of people presenting with sore throat [ Bisno , 2005 ]. However, figures for asymptomatic carriage range from 6% to 40% [ Little and Williamson, 1996 ]. Carriers have low infectivity and are not at risk of developing complications.
      • Swabs may be useful in high-risk groups, to guide the choice of treatment if treatment failure occurs (see the section on Choice of antibiotic ).
    •  
    • Infectious disease. Laboratory medicine practice guidelines: evidence-based practice for point-of-care testing.
      • Guideline 114 .
      • Rapid tests for diagnosis of GAS pharyngitis in general provide clinically useful, financially justified results; these tests also have utility for testing nonpharyngeal specimens. The recommendation of the American Academy of Pediatrics to confirm negative rapid GAS antigen detection results of pharyngeal specimens from children should be followed; the Infectious Diseases Society of America recommendation to perform laboratory tests (either throat culture or rapid antigen detection) on specimens from adults with clinical evidence of pharyngitis should be followed.
      • Strength/consensus of recommendation: A
      • Level of evidence: III
      BIBLIOGRAPHIC SOURCE(S) Campbell S, Campos J, Hall GS, LeBar WD, Greene W, Roush D, Rudrik JT, Russell B, Sautter R. Infectious disease. In: Laboratory medicine practice guidelines: evidence-based practice for point-of-care testing. Washington (DC): National Academy of Clinical Biochemistry (NACB); 2006. p. 76-94. [195 references]
    • Sore throat and tonsillitis
      • Streptococcal culture or rapid test is the most important investigation. Clinical assessment is not accurate in determining the microbial aetiology.
      • Culture of a throat swab is the most accurate and least expensive method, provided that notification of the result to the patient and delivery of the prescription to the pharmacy are organized effectively.
      • Streptococcal culture also reveals non-A streptococci (no inhibition of haemolysis around a bacitracin disk).
      • If a rapid test is used, a negative result should be confirmed by culture (confirmation of a negative test is not necessary in children under the age of 3 years, as streptococcal disease is uncommon in this age group).
      Finnish Medical Society Duodecim (FMSD) . Sore throat and tonsillitis. In: EBM Guidelines. Evidence-Based Medicine [Internet]. Helsinki, Finland: Duodecim Medical Publications Ltd.; 2007 Feb 2. [Various].
    • Diagnosis and treatment of respiratory illness in children and adults.
      • An appropriately performed throat swab touches both tonsillar pillars and the posterior pharyngeal wall. The tongue should not be included (although its avoidance is sometimes technically impossible). Backup strep culture is needed if rapid strep test is negative. The best yield is obtained by using separate swabs for rapid strep test and strep culture. Backup systems such as polymerase chain reaction (PCR) may also be used.
      Institute for Clinical Systems Improvement (ICSI). Diagnosis and treatment of respiratory illness in children and adults. Bloomington (MN): Institute for Clinical Systems Improvement (ICSI); 2008 Jan. 71 p. [175 references]
      • Rapid strep test has the following advantages:
      • • It has nearly 100% specificity.
      • • Rapid turnaround time reduces unnecessary short-term treatment while awaiting test results and the associated complexity of interim treatment strategies.
      • • It potentially reduces need for callbacks.
      • • It allows the initiation of antibiotic in the timeliest fashion, reducing acute morbidity and contagion.
      • • Overall, rapid strep test may be more cost effective through reduced rework and reduced cycle time (Lieu, 1990 [M]).
      • • Rapid strep test has high patient satisfaction, even with associated wait time for results.
      • Rapid strep test has the following disadvantages or limitations :
      • • Lab costs are increased.
      • • Current technology requires that negative rapid strep tests be backed up with strep culture because of relatively low sensitivities. Recent reports of new technology for optical immunoassay (OIA) are encouraging for ultimately being able to use rapid strep test without culture backup. However, to date, results of studies on optical immunoassay are limited and conflicting. Until more data is available, it is recommended that all negative rapid strep tests be backed up with strep culture (Gerber, 1997 [C]; Schlager, 1996 [C]).
      • • Recent study indicates the utility of a real-time polymerase chain reaction assay as a replacement for both rapid antigen testing and culture (Uhl, 2003 [C]). The polymerase chain reaction method requires a minimum of 30 to 60 minutes to perform the test, and in order to be used efficiently, it would require batch testing. It is unlikely that this polymerase chain reaction method would be used as a waiting/rapid test.
      • • Clinics may need to arrange new patient flow in the office and need to determine who will perform rapid strep test.
      • • False positives may occur with retesting for up to 14 days following antibiotic course completion (presumably due to incomplete clearing of strep antigen fragments that are still detected after clinical recovery).
      • • It does not differentiate between illness and carrier states.
    •  
    •  
    • Pharyngitis
      • Laboratory confirmation: Test when diagnosis is not ruled out by viral symptoms (see table below).
      • For adults: confirmation is most useful when GABHS is suspected; however, only test those with at least 2 or more signs/ symptoms mentioned above. [C] .
      • For patients between 3 to 15 years of age: confirmation is most useful when GABHS cannot be excluded. Nevertheless, only test those with at least 1 or more signs/symptoms mentioned above [C] . The threshold for testing is lower for children because their risk of developing acute rheumatic fever is higher.
      University of Michigan Health System. Pharyngitis. Ann Arbor (MI): University of Michigan Health System; 2006 Oct. 10 p. [9 references]
      • Throat culture is the presumed &quot;gold standard&quot; for diagnosis [C] . Rapid streptococcal antigen tests identify GABHS more rapidly, but have variable sensitivity [C] .
      • Reserve rapid strep tests for patients with a reasonable probability of having GABHS. In patients screened with a rapid strep test, a negative result should be confirmed by culture in patients <16 years old (and considered in parents or siblings of school age children) due to their higher incidence of developing acute rheumatic fever [C] .
      • If screening for GABHS in very low risk patients is desired, culture alone is cost effective.
      Pharyngitis University of Michigan Health System. Pharyngitis. Ann Arbor (MI): University of Michigan Health System; 2006 Oct. 10 p. [9 references]
    •  
    • SIGN
      • DIAGNOSIS OF SORE THROAT
      • (B) Clinical examination should not be relied upon to differentiate between viral and bacterial sore throat.
      • (B )Throat swabs should not be carried out routinely in sore throat.
      • (B) Rapid antigen testing should not be carried out routinely in sore throat.
      Published January 1999.  Due for review 2007/8, but publisher has confirmed the guideline's continued validity (November 2007).
    •  
      • Recommendation 1: Throat swab for culture: when and how
      • A throat swab should be taken when a diagnosis of strep throat is suspected from the clinical and epidemiological findings and the patient is not already taking antibiotics.
      • Technique: Using a sterile throat swab, contact the posterior pharyngeal wall and the surface of both tonsils, then place in an appropriate transport medium for prompt delivery to the laboratory.
      • A culture is usually the only test required. However, antibiotic sensitivity should also be requested in penicillin allergic patients due to the emergence of erythromycin resistant strains of streptococcus.
      • A culture is not indicated following a course of antibiotics for strep throat unless symptoms persist. Asymptomatic contacts of a patient with strep throat do not require cultures or empiric antibiotics
      Revised Date: April 1, 2007
        • Rapid strep (antigen detection) tests lack sensitivity, lack evidence of improved clinical outcome and are NOT recommended.
      • DARE, NHS Economic Evaluations Database y HTA
    • Culture confirmation of rapid antigen detection (RAD) test-negative results may be unnecessary in children with pharyngitis, due to the low rate of false-negative results when all patients are tested. The economic analysis showed that substantial cost-savings may be realised from eliminating follow-up throat cultures, as a confirmation of negative RAD test results, from the point of view of the private practice and the patient. The cost of complications for undetected infections was fairly low. Economic evaluation Are follow-up throat cultures necessary when rapid antigen detection tests are negative for Group A streptococci? Mayes T, Clinical Pediatrics 2001 Economic evaluation Economic evaluation Economic evaluation Economic evaluation From a health care payer perspective, the &quot;no testing and no treatment&quot; strategy resulted in the lowest morbidity and lower costs. The rapid antigen testing approach had the best cost-utility ratio. From a societal perspective, observing patients with pharyngitis resulted in the lowest morbidity rate while the approach of testing all patients using throat culture demonstrated a better cost-utility ratio. Diagnosis and management of pharyngitis in a pediatric population based on cost-effectiveness and projected health outcomes Van Howe R S, Pediatrics 2006 The authors concluded &quot;the most cost effective method of reducing the incidence of RHD (rheumatic heart disease) in a paediatric population presenting with pharyngitis potentially caused by a GAS (group A streptococcal) infection is the rapid antigen test with concomitant antibiotic treatment without the use of any confirmatory culture&quot;. Cost-effectiveness of treatment options for prevention of rheumatic heart disease from group A streptococcal pharyngitis in a pediatric population Ehrlich J E, Preventive Medicine 2002 Observation, culture, and two rapid antigen test strategies for the diagnostic testing and treatment of suspected beta-haemolytic streptococcus (GAS) pharyngitis in adults had very similar effectiveness and costs, although culture was the least expensive and most effective strategy when the GAS pharyngitis prevalence was 10%. Diagnosis and management of adults with pharyngitis: a cost effectiveness analysis Neuner J M, Annals of Internal Medicine 2003 Authors' conclusions: Selective use of a rapid streptococcal antigen test (RSAT) in patients with at least 2 clinical findings suggestive of Group A streptococcal pharyngitis (GASP) is a cost-effective strategy to reduce the overuse of antibiotics and to appropriately treat acute pharyngitis in adults in a primary care setting. Management of acute pharyngitis in adults: reliability of streptococcal test and clinical findings Humair J P, Annals of Internal Medicine 2003
    • Otras fuentes…
      • Throat swabs have a limited place in routine use because they cannot distinguish between GABHS infection and carriage, and the delay in obtaining results limits clinical utility. In the UK, rapid antigen tests are also not currently recommended for routine use because of their limited specificity and sensitivity (their ability to rule in people with GABHS and to rule out people without the infection, respectively).
      Dec 2006
    • Practice Guidelines Diagnosis and Management of Group A Streptococcal Pharyngitis Barrett M. Schroeder
      • The Infectious Diseases Society of America (IDSA) recently updated a 1997 guideline for the diagnosis and management of group A streptococcal pharyngitis. The revised guideline was published in the July 15, 2002 issue of Clinical Infectious
      • The IDSA recommends that, if acute group A streptococcal pharyngitis is suspected, laboratory testing should be performed to support the diagnosis. Throat culture or a rapid antigen detection test (RADT) may be used.
      • Culture of a throat swab specimen remains the standard for identifying group A beta-hemolytic streptococci (sensitivity: 90 to 95 percent) and confirming the clinical diagnosis. However, culture results are not available for a day or longer. RADTs identify group A streptococcal carbohydrate on a throat swab. Compared with blood agar plate culture, most currently available RADTs have excellent specificity (greater than 90 percent) but lower sensitivity (80 to 90 percent or less). For some RADTs, the Clinical Laboratory Improvement Act has not waived the need for laboratory certification.
    • Practice Guidelines Diagnosis and Management of Group A Streptococcal Pharyngitis Barrett M. Schroeder
      • The IDSA notes that a positive result on a throat culture or RADT adequately confirms the diagnosis. Unless the physician has determined that the RADT used is comparable to throat culture, negative RADT results in children and adolescents should be confirmed with a throat culture. In adults, RADTs are an acceptable alternative to throat culture for the diagnosis of group A streptococcal pharyngitis. Because of the low incidence of streptococcal infection in adults and the extremely low risk of rheumatic fever, negative RADT results do not have to be confirmed by culture in adult patients.
      • Except in patients with a history of rheumatic fever, follow-up culture is not routinely indicated if a course of appropriate antibiotic therapy has been completed and symptoms are absent. Follow-up culture should be considered during outbreaks of acute rheumatic fever or poststreptococcal acute glomerulonephritis, during outbreaks of group A streptococcal pharyngitis in closed or partially closed communities, or when &quot;ping-pong&quot; spread has been occurring within a family.
    •  
      • P – nuestro paciente con faringoamigdalitis
      • I – uso del streptotest
      • C – frente al cultivo faringeo / clinica
      • O – ayuda a tomar decisiones clinicas?
    •  
    •  
    •  
      • 90 pacientes cultivo pos (sensibilidad)
      • 280 pacientes cultivo neg (especificidad)
    •  
    •  
      • Gracias !!!