Community‐acquired bacteremic pneumococcal pneumonia in children: diagnosis and serotyping by real‐time polymerase chain reaction using blood samples.
BACKGROUND
The aim of this study was to use real-time polymerase chain reaction (RT-PCR) on blood samples to diagnose and serotype pneumococcal infection in a large cohort of Italian children hospitalized for community-acquired pneumonia.


METHODS
We conducted an observational study from April 2007 through June 2009 of children aged 0-16 years with a diagnosis of community-acquired pneumonia admitted to 83 pediatric hospitals in Italy.


RESULTS
Seven hundred fifty-three children were studied. RT-PCR found pneumococcal infection in 80 (10.6%) of 753 patients. In 292 patients, culture and RT-PCR were simultaneously performed. Streptococcus pneumoniae was identified in 47 of 292 patients; 45 (15.4%) tested positive by RT-PCR and 11 (3.8%) tested positive by culture. RT-PCR was significantly more sensitive than culture in revealing bacteremic pneumonia (odds ratio, 30.6; 95% confidence interval, 5.8-97.5; P<.001). Complicated pneumonia was found in 162 (21.5%) of 753 children; 152 (93.8%) of these 162 had parapneumonic effusion, and 51 (33.6%) had empyema. Children with complicated pneumonia were significantly older. Pneumococcal bacteremia was found by RT-PCR to occur significantly more frequently in children with complications (38 [23.5%] of 162) than in children with uncomplicated pneumonia (44 [7.4%] of 591; odds ratio, 3.8; 95% confidence interval, 2.30-6.30; P<.001). RT-PCR allowed serotyping from blood in 92.5% of patients. More than two-thirds of the pneumonia cases were due to nonpneumococcal conjugate vaccine 7 serotypes. Serotype 1 was the most frequent serotype (26 [32.5%] of 80) and was significantly associated with complications (50.0% in patients with complicated pneumonia vs 18.2% in patients with uncomplicated pneumonia; odds ratio, 4.5, 95% confidence interval, 1.48-14.03; P=.005) and older age. Serotype 19A was second in frequency (15.0%) and was significantly associated with younger age.


CONCLUSIONS
RT-PCR allows diagnosis and serotyping of pneumococcal bacteremic community-acquired pneumonia in children and is an important tool for evaluating serotype distribution in culture-negative samples.
Resti
Massimo
M
Department of Pediatrics, University of Florence, and Anna Meyer Children's Hospital, Florence, Italy. m.resti@meyer.it
Moriondo
Maria
M
Cortimiglia
Martina
M
Indolfi
Giuseppe
G
Canessa
Clementina
C
Becciolini
Laura
L
Bartolini
Elisa
E
de Benedictis
Fernando Maria
FM
de Martino
Maurizio
M
Azzari
Chiara
C
D000293:Adolescent; D016470:Bacteremia / Q000150:complications* / Q000175:diagnosis* / Q000382:microbiology; D015373:Bacterial Typing Techniques / Q000379:methods*; D001769:Blood / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007558:Italy; D008297:Male; D011018:Pneumonia, Pneumococcal / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D012703:Serotyping / Q000379:methods; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification