Abstract
BackgroundStreptococcus pneumoniae remains a major cause of childhood morbidity and mortality worldwide. Nasopharyngeal colonization plays an important role in the development and transmission of pneumococcal diseases, and infants and young children are considered to be the main reservoir of this pathogen. The aim of this study was to evaluate the rates and characteristics associated with nasopharyngeal carriage, the distribution of serotypes and the antimicrobial resistance profiles of Streptococcus pneumoniae among children in a large metropolitan area in Brazil before the introduction of the 10-valent pneumococcal conjugate vaccine.MethodsBetween March and June 2010, nasopharyngeal swabs were collected from 242 children aged <6 years attending one day care center and the emergency room of a pediatric hospital. Pneumococcal isolates were identified by conventional methods and serotypes were determined by a sequential multiplex PCR assay and/or the Quellung reaction. The antimicrobial susceptibilities of the pneumococci were assessed by the disk diffusion method. MICs for erythromycin and penicillin were also performed. Erythromycin resistance genes were investigated by PCR.ResultsThe overall colonization rate was 49.2% and it was considerably higher among children in the day care center. Pneumococcal carriage was more common among day care attenders and cohabitants with young siblings. The most prevalent serotypes were 6B, 19F, 6A, 14, 15C and 23F, which accounted for 61.2% of the isolates. All isolates were susceptible to clindamycin, levofloxacin, rifampicin and vancomycin. The highest rate of non-susceptibility was observed for sulphamethoxazole-trimethoprim (51.2%). Penicillin non-susceptible pneumococci (PNSP) accounted for 27.3% of the isolates (MICs of 0.12-4 μg/ml). Penicillin non-susceptibility was strongly associated with serotypes 14 and 23F. Hospital attendance and the presence of respiratory or general symptoms were frequently associated with PNSP carriage. The two erythromycin-resistant isolates (MICs of 2 and 4 μg/ml) belonged to serotype 6A, presented the M phenotype and harbored the mef(A/E) gene.ConclusionsCorrelations between serotypes, settings and penicillin non-susceptibility were observed. Serotypes coverage projected for the 10-valent pneumococcal conjugate vaccine was low (45.5%), but pointed out the potential reduction of PNSP nasopharyngeal colonization by nearly 20%.
Highlights
Streptococcus pneumoniae remains a major cause of childhood morbidity and mortality worldwide
In the single study available on the etiology of acute otitis media (AOM) among Brazilian patients, S. pneumoniae was reported as the prevalent agent [8], which is consistent with findings of other geographical regions [3]
Despite high rates of non-susceptibility to penicillin and sulphamethoxazole-trimethoprim, the pneumococcal isolates recovered from nasopharynx of the children analyzed in this study showed a high degree of susceptibility for the majority of the antimicrobial agents tested and, as previously reported [19,20], this may reflect the characteristics of the pneumococcal isolates associated with diseases in our region
Summary
Streptococcus pneumoniae remains a major cause of childhood morbidity and mortality worldwide, in lower income countries. Pneumococcal diseases are the leading source of vaccine preventable deaths, mostly due to community-acquired pneumonia (CAP) [1], accounting for approximately 11% of all deaths in children under 5 years old, excluding neonatal and/or HIV-positive deaths [2]. This microorganism is frequently associated with bacteremia and meningitis, and it is the most common agent of acute otitis media (AOM) in young children [3]. In the single study available on the etiology of AOM among Brazilian patients, S. pneumoniae was reported as the prevalent agent [8], which is consistent with findings of other geographical regions [3]
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