Antibiotic susceptibility and capsular genes of <i>Streptococcus pneumoniae</i> colonizing children with chronic respiratory diseases

Abstract

Background: Streptococcus pneumoniae (S. pneumoniae) is a main pathogen causing acute infectious exacerbations in chronic lung diseases (CLD) children. Determining the local antibiotic susceptibility pattern of colonizing strains in these patients is crucial for empirical therapy. Moreover, identifying prevalent types is important to evaluate the effectiveness of available vaccines. This study aimed to detect antibiotic susceptibility and searching for some capsular gene types among S. pneumoniae isolates colonizing respiratory tract in CLD children.

Methods: Bronchoalveolar lavage (BAL) samples were collected from 51 CLD children undergoing bronchoscopy in Ain Shams University Pediatric Hospital. All identified S. pneumoniae isolates were tested for antibiotic susceptibility. Two-steps sequential multiplex PCR technique was performed to detect capsular gene types: [3/ 22f/(22A) / 19A / 6A/6B /4 / 14/ 12F/(12A) / 9V/(9A).

Results: From 51 BAL samples, 32 (62.75%) pneumococcal strains were isolated. Most of the isolates had capsular gene type 6A/6B (65.6%). Capsular gene type 14 was detected in 25% of isolates. In 9.4% of strains, capsular type could not be identified. All isolates were sensitive to vancomycin. The lowest resistance rate was to levofloxacin (6.3%) and linezolid (9.4%), while the highest rates were to clindamycin (71.9%) and erythromycin (68.8%).

Conclusion: Streptococcus pneumoniae colonizing CLD children showed high resistance to clindamycin and erythromycin thus highlighting the importance of antimicrobial stewardship programs in all levels of healthcare. Capsular gene type 6A/6B was the commonest colonizing type suggesting that CLD children can benefit from the currently available PCV13 vaccine.