Serotipos no vacunales emergentes causantes de enfermedad neumocócica invasora en la era de la vacuna 7-valente

ResumenIntroducciónTras la introducción de la VNC7 se ha objetivado una importante expansión de algunos serotipos emergentes (SNV) de Streptococcus pneumoniae, siendo los principales productores de enfermedad neumocócica invasora (ENI) actualmente. Nuestro objetivo ha sido describir los aspectos epidemiológicos, clínicos y microbiológicos de la ENI producida por SNV en un hospital terciario de Madrid.Pacientes y métodosEstudio retrospectivo (1998-2004) y prospectivo (2005-2009) de los SNV productores de ENI. Se analizaron 3 periodos de estudio: P1 (1998-2001), sin comercialización de la VNC7, P2 (2002-2005), con una cobertura vacunal del 40% y P3 (2006-2009), con la vacuna incorporada al calendario vacunal de la Comunidad de Madrid.ResultadosSe analizaron 155 casos de ENI, de los que se pudieron serotipar 150 aislamientos (100 de ellos SNV). Se produjo un incremento de la prevalencia de SNV desde P1 (31%) a P2 (53,6%) y P3 (91,3%). Los serotipos emergentes más prevalentes fueron 19A, 1, 5, 3, 7 F y 15C. Los serotipos 1, 3, 5 y 15C produjeron, fundamentalmente, enfermedad respiratoria; el serotipo 19A tanto enfermedad respiratoria como bacteriemia primaria, siendo la principal causa de meningitis; el serotipo 7 F produjo, fundamentalmente, bacteriemia primaria (66%). El 83,8% de los SNV fueron sensibles a penicilina.ConclusionesDesde la introducción de la VNC7 se ha objetivado un aumento de la prevalencia de ENI producida por SNV. Estos cambios encontrados deberían hacer considerar la utilización de las vacunas antineumocócicas ampliadas para la prevención de ENI, al incluir la mayoría de los SNV emergentes.

IntroductionThere has been an increased incidence in invasive pneumococcal disease (IPD) produced by non-vaccine serotype (NVS) of Streptococcus pneumoniae after the introduction of PCV7. Our objective was to describe the epidemiological, clinical and microbiological characteristics of IPD caused by NVS in a tertiary hospital in Madrid.Patients and methodsRetrospective (1998-2004) and prospective (2005-2009) study evaluating IPD caused by NVS in children. The study was divided into three periods: P1 (1998-2001) when PCV7 was not commercialized; P2 (2002-2005) with 40% vaccine coverage among children; and P3 (2006-2009) when the vaccine was added to the Childhood Immunization Schedule in Madrid.ResultsWe analyzed 155 cases of IPD. One hundred and fifty of these isolates were serotyped (100 were NVS). There was an increase in the prevalence of IPD from P1 (31%) to P2 (54%) and P3 (91%). The most relevant emerging serotypes were 19A, 7 F, 1, 5, 3 and 15C. The most significant clinical syndromes produced by some specific serotypes were as follows: lower respiratory tract infection (LRTI) by serotypes 1, 3, 5 and 15C; LRTI, primary bacteremia and meningitis by serotype 19A; and primary bacteremia by serotype 7 F (66%). The large majority (83.8%) of NVS were sensitive to penicillin.ConclusionsThere has been an increased prevalence of IPD caused by NVS since the introduction of PCV7. These changes should prompt the introduction of new pneumococcal vaccines, which include most of the NVS, in the childhood immunization calendar to prevent IPD in children.