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Nasopharyngeal colonization of infants in southern India with Streptococcus pneumoniae
R Jebaraj1, T Cherian, P Raghupathy
1Department of Child Health, Christian Medical College and Hospital, Vellore, India.
Insights
Most infants experience Streptococcus pneumoniae colonization, with common serogroups like 6 and 19. Antimicrobial resistance was low, but invasive isolates showed higher resistance to cotrimoxazole.
Area of Science:
- Microbiology
- Pediatrics
- Epidemiology
Background:
- Nasopharyngeal colonization by Streptococcus pneumoniae is common in infants.
- Understanding the dynamics of colonization, prevalent serogroups/types (SGT), and antimicrobial susceptibility is crucial for public health.
Purpose of the Study:
- To investigate the dynamics of nasopharyngeal colonization with Streptococcus pneumoniae in infants.
- To determine the prevalent SGTs and their antimicrobial susceptibility.
- To compare susceptibility patterns between colonizing and invasive isolates.
Main Methods:
- Prospective study of 100 infants from a well-baby clinic.
- Nasopharyngeal swabs collected at multiple time points (6 weeks to 18 months).
- Culture, serotyping, and antimicrobial susceptibility testing of Streptococcus pneumoniae isolates.
Main Results:
- 81% of infants were colonized at least once, with median acquisition at 11 weeks and carriage duration of 1-3 months.
- Common SGTs identified were 6, 19, 14, and 15; SGT 1 was notably absent.
- Low resistance rates observed for penicillin (0%), chloramphenicol (6%), cotrimoxazole (5%), and erythromycin (3%).
- Invasive isolates showed significantly higher resistance to cotrimoxazole compared to colonizing isolates (40% vs. 5%, P<0.0001).
Conclusions:
- Infant nasopharyngeal colonization with Streptococcus pneumoniae is highly prevalent.
- Specific SGTs dominate colonization, with notable absence of SGT 1.
- Low antimicrobial resistance in colonizing strains, but higher resistance in invasive strains warrants further investigation.
Abstract:
To investigate the dynamics of nasopharyngeal colonization with Streptococcus pneumoniae, and to determine the prevalent serogroups/types (SGT) and their antimicrobial susceptibility, we studied 100 infants attending our well-baby clinic. Nasopharyngeal swab specimens were obtained at 6, 10, 14, 18 and 22 weeks and at 9 and 18 months of age and submitted for culture, serotyping and antimicrobial susceptibility testing of S. pneumoniae. Colonization with pneumococcus was seen on at least one occasion in 81 infants. The median age of acquisition was 11 weeks and the median duration of carriage was 1 3 months. The common SGTs identified were 6, 19, 14 and 15. SGT 1, which was a common invasive isolate in children in our hospital during this period, was not isolated from these children. Sequential colonization by 2, 3 or 4 SGTs was observed in 18, 5 and 2 children, respectively. Resistance to penicillin, chloramphenicol, cotrimoxazole and erythromycin was observed in 0, 13 (6%) 11 (5 %) and 5 (3 %) isolates, respectively. There was a significant difference in susceptibility to cotrimoxazole between colonizing and invasive isolates (5 % vs. 40 %, P<0.0001).