Risk Factors for the Nasopharyngeal Carriage of Respiratory Pathogens by Portuguese Children: Phenotype and Antimicrobial Susceptibility ofHaemophilus influenzaeandStreptococcus pneumoniae

Abstract

Between 1997 and 2000 nasopharyngeal specimens were obtained from 466 children < or = 12 years old attending the Pediatric Emergency Department at S. Francisco Xavier Hospital, Lisbon, to evaluate risk factors for nasopharyngeal carriage of Haemophilus influenzae and Streptococcus pneumoniae and to characterize their phenotype and antimicrobial susceptibility. The attending pediatrician completed written questionnaires about the children's demographic and clinical histories. Over half the children (52.8%) carried H. influenzae and/or S. pneumoniae. Forty-one percent of these children had H. influenzae, 22.8% had S. pneumoniae and 36.2% had both. Risk factors identified for carriage of respiratory pathogens were: age below 3 years (p < 0.05), black race (p < 0.01), attending a daycare center (p < 0.05), and having a lower respiratory infection (p < 0.05). Asthmatic children were less likely to be carriers (p = 0.004). About two-thirds of H. influenzae isolates were susceptible to all antibiotics tested, 7.9% were beta-lactamase producers, 16.4% were nonsusceptible to trimethoprim, and 6.9% were intermediately resistant to clarithromycin. Over half (57.1%) of S. pneumoniae isolates were susceptible to all antibiotics tested, 21.1% were multiresistant, 23.3% were nonsusceptible to penicillin, and about 20% were resistant to macrolides. Low-level resistance to third-generation cephalosporins was detected in 2.3%. The data reflect the controversy surrounding risk factors of nasopharyngeal colonization. These may have significant implications on clinical practice and on antimicrobial strategies to prevent the appearance of further resistant strains. Our findings highlight the importance to investigate the relationship between asthma and carriage.

Co-infection subverts mucosal immunity in the upper respiratory tract

“…Significantly high carriage rates (>50%) of both of these organisms in children suggest that co-colonization is common [9]. Competition between these organisms is likely due to the overlap in their site and frequency of colonization.…”

Correlation of Bacterial Colonization Status between Mother and Child: the Generation R Study

“…pneumoniae and M. catarrhalis often colonize children but are not frequently found in adults (5,15,18,23), whereas S. aureus is more commonly found in adults. About 25% to 37% of the healthy adult population carries S. aureus in the anterior nares (14,24).…”

“…The S. aureus colonization rate steeply decreases in the first year of life (16,3). Forty-four percent to 64% of children up to the age of 3 years have been colonized with or infected by H. influenzae at least once (5,8,18). Little is known on bacterial colonization in healthy family settings.…”

Synergistic proinflammatory responses induced by polymicrobial colonization of epithelial surfaces

“…Both commonly exist as commensal organisms in the human nasopharynx and are capable of causing disease when they are able to gain access to other normally sterile sites. Asymptomatic carriage of each species may be stable over weeks or months and occurs in greater than half of some populations, especially young children (6). These factors imply that concurrent exposure of mucosal surfaces to these two species may not be a rare event.…”