[Bacteremic pneumococcal pneumonia]

Abstract

Background: Streptococcus pneumonia is the most common bacterial cause of community-acquired pneumonia in children. The reference standard for etiological diagnosis is isolation of S. pneumoniae from blood Since the advent of conjugate vaccines, disease caused by this organism can now be prevented. Many studies have been performed of the global incidence of invasive pneumococcal infections and of pneumococcal meningitis but few studies investigated bacteremic pneumococcal pneumonia and its complications in children.

Objectives: To determine the incidence, patient characteristics, clinical signs, laboratory data, percentage and days of hospitalization, response to antibiotic treatment, antibiotic resistance, complications and causal serogroups of bacteremic pneumococcal pneumonia in our environment in order to estimate requirements for systematic vaccination programs.

Material and methods: From January 1990 to May 2001, data on all pediatric cases of invasive pneumococcal infections diagnosed in our hospital were collected. Several characteristics of patients with bacteremic pneumococcal pneumonia were analyzed. Bacteremic pneumococcal pneumonia was diagnosed in patients with positive blood or pleural fluid cultures for S. pneumoniae and radiographically evident pulmonary infiltrate. The incidence of both types of pneumonia were determined according to population census data. All S. pneumonia strains were sent to the Pneumococci Reference Laboratory of the Instituto Carlos III in Madrid for serotyping. We estimated the serotype coverage of the pneumococcal 7-valent conjugate vaccine according to the serotypes included in this vaccine and their distribution.

Results: Forty cases of bacteremic pneumococcal pneumonia were diagnosed, yielding an incidence of 17,10 and 5 cases per 10(5) children aged less than 2, 4 and 15 years old respectively. The mean age was 50 months and 43% were aged less than 4 years. Peaks occurred in January, March, April and May. A total of 77.5% of the patients were admitted to hospital and the mean length of stay was 9.2 days. The mean duration of fever was 2 days and was 4.2 days in patients with pleural empyema. All patients presented fever and its mean duration before admission was 4 days. Fifty-eight percent of the patients had cough. Thirty-nine percent appeared generally unwell, vomiting was present in 47% and abdominal pain in 28%. Respiratory auscultation detected rales in 30% of the patients, hypophonesis in 28% and polypnea or dyspnea in 35%. Most patients showed alveolar bilateral infiltrations and 20% had pleural empyema. Seventy-eight percent had WBC counts > 15,000 and 93% showed neutrophilia of > 60%. Erythrocyte sedimentation rate and C-reactive protein were elevated in 77% and 85% of the patients, respectively. Overall, 40% of the isolates showed intermediate susceptibility to penicillin and 5% were resistant. Eighteen percent showed intermediate susceptibility to cefotaxime and 18% were resistant to erythromycin. Thirty-four strains were resistant to erythromycin. Thirty-four strains were serogroups and in children < or = 59 months, 34% of the serogroups were included in the pneumococcal 7-valent pneumococcal conjugate vaccine.

Conclusion: The significant morbidity of bacteremic pneumococcal pneumonia and the implicated serogroups supports the use of the new heptavalent vaccine in the pediatric age group.