This study is a review of pediatric CAP (diagnosed by consolidation on initial chest radiograph and compatible clinical history) at a pediatric hospital, two years after the introduction of universal PCV-7 pneumococcal vaccination. Previous reviews have had smaller sample size, were less comprehensive, were limited to developing nations, or were completed prior to the introduction of the conjugated seven valent pneumococcal vaccine [10
Since the diagnosis of CAP is often based on a compatible clinical presentation and a CXR finding of consolidation, we chose these as practical requirements for study inclusion. Our sample selection was an attempt to increase the probability of capturing and evaluating bacterial pneumonias given that consolidation is most frequently associated with bacterial infection [11
]. The small sample size of the radiographs that were reviewed by the radiologists likely resulted in the low kappa scores. These values are comparable to published results, and acknowledge the inter-observer variability in interpretation of chest radiographs in the absence of clinical information [11
This study supports the significant continuing health care burden of children hospitalized with consolidative pneumonia in the era of PCV-7 use. [29
] In this cohort, two-thirds of patients had at least one visit to a physician prior to their hospitalization and the average length of hospital stay was 4 days. One quarter of children had 3 or more CXRs, and nearly 20% had an invasive procedure done (chest tube insertion or VATS).
Our study found that patients presenting with effusion were not more likely to be younger, febrile, tachypneic or have a higher WBC count than those without effusion, underscoring the importance of chest radiography in pediatric CAP. Other authors have supported the importance of early radiologic evaluation in differentiating early complicated versus uncomplicated lobar pneumonia [25
]. Children with an effusion were more likely to be admitted to the intensive care unit.
Only 9 of the 117 (7.7%) patients had bacterial pathogens identified in blood or pleural fluid. Seven had Streptococcus pneumoniae
(6 in blood and 1 in pleural fluid) and 1 child had Group A streptococcus
isolated from pleural fluid. The incidence of bacteremia was 6%, which is comparable to a recent study evaluating children with CAP in the Emergency Department [31
], but lower than bacteremic rates published previously in the literature [12
]. This is likely due to the fact that 42% of children in this cohort had antimicrobials prior to hospital presentation.
PCV-7 has been included in the publicly-funded routine immunization schedule in Ontario since 2005. By parental report, the majority of children had up-to-date vaccination series for age. Six of the seven S. pneumoniae serotypes identified in blood or pleural cultures were not PCV-7 serotypes, but would have been included in PCV-13 (Prevnar13®) or PCV-10 (Synflorix®) coverage. (4/6 children with PCV-13 vaccine serotypes would have been age-eligible for immunization and therefore had infection potentially preventable with PCV-13.) The only vaccine-preventable serotype (9 V) occurred in a 16-year-old youth who would not have received PCV-7 immunization. The only bacteremic serotype in this cohort not included in the 7, 10 or 13-valent vaccines was 11A.
Current pediatric CAP guidelines and reviews recommend consideration of treatment with intravenous ampicillin or penicillin for hospitalized children, given the evidence for its comparable effectiveness to cefuroxime for more severe pneumonia. [12
]. Despite this, less than 5% of children received a penicillin as initial therapy. Only 19% of children with uncomplicated pneumonia received amoxicillin at discharge, and only 2 of the 7 patients with confirmed S. pneumoniae
were discharged on amoxicillin. All S. pneumoniae
isolates in this study were penicillin susceptible. (CHEO’s 2010 Antibiogram reports a 97% susceptibility of S. pneumoniae
to penicillin [36
].) Cephalosporins were prescribed in 96% of patients in this cohort rather than narrower-spectrum, less expensive antimicrobial agents, such as penicillin or ampicillin. We acknowledge that prior antimicrobial use may have influenced the physician’s antimicrobial choice on admission. Antimicrobial stewardship intiatives and recently published guidelines aimed at use of ampicillin or penicillin G (as opposed to broader spectrum coverage with second and third generation cephalosporins) may alter prescribing trends in the future.
Guidelines recommend empiric coverage with a macrolide in older children because Mycoplasma pneumoniae
is more prevalent in this group [12
]. More recent data has shown that Mycoplasma pneumoniae
may play a more important role in the younger age group than previously believed [26
]. Further studies may alter the current recommendations regarding the use of macrolides in pediatric CAP, however macrolide use should be cautioned in areas where there is significant pneumococcal resistance to macrolides. In this study, macrolides were used frequently in the younger age group - nearly half of children under age 5 years were treated with a macrolide either in hospital or at discharge.
The limitations of the retrospective nature and design of the study did not permit verification of specific immunization status for PCV-7. Microbiological data was also not available for all patients. Our inclusion criteria of consolidative pneumonia would have excluded patients with very early pneumonias that did not have established consolidation on initial CXR. The study results however, are generalizable to healthy children who are hospitalized for consolidative pneumonia in populations where PCV-7 is routinely administered to children.