Five-Fold Increase in Pediatric Parapneumonic Empyema Since Introduction of Pneumococcal Conjugate Vaccine

Abstract

A retrospective review of medical records for all pediatric parapneumonic empyema (PPE) patients admitted to our hospital from 1996 to 2006 revealed that PPE increased 5-fold in the post-heptavalent pneumococcal conjugate vaccine (PCV7) period (2001-2005) relative to the pre-PCV7 period (1996-2000), from 13 cases to 65. Most of this increase was associated with culture-negative empyema, which accounted for 61% of all post-2000 cases; 19% was culture-positive pneumococcal empyema. Our analysis indicates that non-PCV7 serotypes became more prevalent at our institution after introduction of the vaccine.

Increased paediatric hospitalizations for empyema in Australia after introduction of the 7-valent pneumococcal conjugate vaccine

“…24,25 The reported increase in serotypes 1, 3 and 19A among invasive isolates might explain the increase in empyema but not in pneumonia per se. [10][11][12] On the other hand, an increase in the incidence of empyema was observed in some studies before the introduction of the PCV7. 2,[26][27][28] This suggests that the observed association between the introduction of the PCV7 and the rise in empyema incidence may be coincidental.…”

“…22 Although the PCV7 has substantially reduced the rates of invasive pneumococcal disease, reports from around the world suggest that the incidence of empyema in children has increased following the introduction of the PCV7. 10,11 The reasons for this are not entirely clear, but virulent serotypes not covered by the PCV7 may have emerged as a result of the selective pressure applied by the vaccine. Most cases of empyema among Australian children are caused by serotypes 1, 3 and 19A, 23 which are believed to be particularly virulent and more likely to invade the pleural cavity.…”

“…[10][11][12][13][14][15][16][17] Because up to 90% of these cases have been caused by bacterial serotypes not included in the PCV7, [10][11][12] some fear that empyema may have emerged as a "replacement disease", i.e. disease produced by non-vaccine-related serotypes that have become predominant.…”

Serotypes associated with the development of pneumococcal para-pneumonic effusion in adults

“…That study identified serotypes 1, 3 and 19A as being most frequently found in ''complicated CAP'', which included multilobar disease as well as PPE and empyema. Paediatric PPE increased in incidence following PCV-7 introduction and prior to the introduction of PCV-13 [11,[18][19][20], with PCV-7 NVT serotypes 1, 3, 5, 7F and 19A implicated [10][11][12]. In a small study of paediatric empyema, pneumococci were identified in 13 samples, six of which were serotype 19A and one serotype 1, the others being serotypes 14 (n51), 34 (n51) and untypable (n54) [28].…”

“…Following the introduction of the conjugate vaccines to infant immunisation schedules a shift was observed in the serotypes seen in adult invasive pneumococcal disease towards nonvaccine-type serotypes [16,17]. Some studies have reported a relative rise in the incidence of all-cause and pneumococcal PPE in children following the introduction of PCV-7 [11,[18][19][20], as the serotypes commonly associated with pneumococcal PPE are not included in PCV-7, although in the UK a fall in paediatric empyema hospitalisations was observed [21]. It is too early to say whether there has been a subsequent decrease in the incidence of pneumococcal PPE in children following the introduction of PCV-13 (which includes serotypes 1, 3, 5, 6A, 7F and 19A) due to continued serotype replacement with non-PCV-13 serotypes.…”