Defining the potential impact of conjugate bacterial polysaccharide-protein vaccines in reducing the burden of pneumonia in human immunodeficiency virus type 1-infected and -uninfected children.

BACKGROUND: The evaluation of bacterial conjugate vaccines in preventing pneumonia requires the definition of suitable outcome measures against which their use can be evaluated. One such possible outcome measure is alveolar consolidation confirmed by chest radiograph (CXR).
OBJECTIVE: To define the CXR presentation in relation to identified bacterial and respiratory viral pathogens among HIV-1-infected and -uninfected children.
METHODS: The CXRs of 1186 of 1434 children hospitalized with severe lower respiratory tract infection were evaluated for the presence of alveolar consolidation (homogenous airspace infiltrate), bronchopneumonia (patchy airspace consolidation) or other CXR findings. Children were also investigated for bacterial infection by blood culture in 1364 of 1434 episodes and for respiratory viruses in 990 of 1434 episodes by immunofluorescein monoclonal antibody assays.
RESULTS: The prevalence of HIV-1 infection among children who had CXRs in the study was 527 (46.2%) of 1142. Alveolar consolidation was more common in HIV-1-infected (63.7%) than in HIV-uninfected children (42.4%, P < 10(-5)) whereas bronchopneumonic changes (29.0% vs. 38.0%, P = 0.001) or a normal CXR occurred in 7.0 vs. 18.2% (P < 10(-5)) of HIV-1-infected and -uninfected children, respectively. Alveolar consolidation was the main CXR presentation in HIV-1-infected (78.6%) and HIV-uninfected children (64.9%, P = 0.14) with all-cause bacteremic pneumonia as well as those with bacteremic Streptococcus pneumoniae pneumonia (76.9% vs. 83.3%, respectively; P = 0.99). Respiratory virus-associated lower respiratory tract infection, however, was more likely to present with alveolar consolidation in HIV-1-infected (55.8%) than in HIV-uninfected (36.1%, P = 0.02) children.
CONCLUSION: Although alveolar consolidation may be a useful tool in defining both the efficacy and burden of bacterial pneumonia in HIV-1-uninfected children, this may not be so for HIV-1-infected children. The higher occurrence of respiratory virus-associated alveolar consolidation, possibly coupled with Pneumocystis carinii pneumonia, may be significant confounders in the interpretation of CXR in HIV-1-infected children, limiting the use of alveolar consolidation as an outcome measure when evaluating the efficacy of bacterial conjugate vaccines in HIV-1-infected children.