Prevalence of Group A Streptococcal Carriers in Asymptomatic Children and Clonal Relatedness among Isolates in Malatya, Turkey

Abstract

In our study, the prevalence of nasopharyngeal Streptococcus pyogenes was 130 (14.3%) of 909 healthy children. Isolates were found to be susceptible to all antibiotics tested. Pulsed-field gel electrophoresis and arbitrarily primed PCR revealed that 34 (32.4%) of the 105 isolates and 41 (40.6%) of the 101 isolates typed, respectively, were clonally indistinguishable.Streptococcus pyogenes group A streptococcus (GAS) strains colonized in the upper respiratory tracts of children play an important role in the spread of this bacterial infection, especially among children at school, day-care centers, orphanages, and home. Study of the prevalence of healthy S. pyogenes carriers and the molecular epidemiology of the isolates may provide useful information about the origin and spread of this infectious agent, allowing for more effective control measures. Pulsed-field gel electrophoresis (PFGE) (3,4,14) has been used as a standard technique for surveying epidemiology of S. pyogenes infections. Although arbitrarily primed PCR (AP-PCR)-based fingerprinting performed with the M13 primer has been widely used for molecular epidemiology of gram-negative (1, 2, 10) and gram-positive bacteria (11), there had been no study about its efficiency in typing S. pyogenes strains.The aims of the present study were to investigate the rate of pharyngeal colonization, drug susceptibility, and the molecular epidemiology of GAS isolated from healthy children and to compare PCR-based fingerprinting with PFGE in the investigation of clonal relatedness among the GAS isolates.Study groups. The study groups included 800 primary schoolchildren and 109 children living in an orphanage in Malatya, Turkey. An otorhinology specialist rubbed sterile swabs over the posterior nasopharyngeal walls of the 909 children, who had no symptoms or signs of pharyngitis. The samples were inoculated on sheep's blood agar plates. After incubation overnight at 37°C, beta-hemolytic streptococci were identified with a bacitracin disk (0.04 U) and a latex test for the identification of streptococcal groups A, B, C, D, F, and G (streptococcal grouping kit and diagnostic reagent; Oxoid Limited, Basingstoke, England).Susceptibility testing. The antimicrobial susceptibilities of the GAS isolates were investigated by the disk diffusion method according to the criteria of the National Committee for Clinical Laboratory Standards (13). The antibiotic disks (Oxoid) used were penicillin (10 U), erythromycin (15 g), vancomycin (30 g), chloramphenicol (30 g), clindamycin (2 g), cefepime (30 g), ceftriaxone (30 g), ofloxacin (5 g), and levofloxacin (5 g).Molecular typing of the strains. Both AP-PCR and PFGE typing was performed on 101 strains which had available stocks. PFGE was also carried out on five additional strains. For AP-PCR typing, isolation of DNA by using lysozyme and proteinase K and extraction were performed by following the protocol of Welsh and McClelland (19). Then AP-PCR, which had previously been optimized (1, 2), was performed with the M13 primer (10). For PFGE, i...

Carriage of Streptococcus pyogenes in Primary School Children: M-Protein Types, Pyrogenic Toxin Genes, and Investigation of the Clonal Relationships Between the Isolates

“…Bunun nedeni olarak anneden geçen koruyucu antikorların varlığı gösterilmektedir. Ül-kemizde yapılan çalışmalarda, GAS taşıyıcılık oranları %2.8 ile %25.9 arasında değişiklik göstermektedir [17][18][19] . Asemptomatik çocuklardaki GAS taşıyıcılığının değerlendirildiği ve tüm dünyadan 21 çalışmanın incelendiği bir meta-analizde, taşıyıcılık oranlarının %3-26 arasında olduğu saptanmıştır 15 .…”

“…Yapılan çalışmalar, okul ve işyeri gibi kalabalık yaşama ortamlarının, etkenin yayılımında önemli olduğunu göster-mektedir [15][16][17][18] . Çalışmamızda, örneklerin toplandığı her iki okulda da baskın bir salgın izolatı tespit edilmemiştir.…”

“…Bu durum, GAS yayılımının okul çağındaki çocuklarda önemli bir risk oluşturduğunu göstermektedir. Bölgemizden yapılan diğer bir çalışmada, asemptomatik 130 okul çocuğundan izole edilen suşlar arasındaki klonal ilişki oranı %36.1 olarak bulunmuş ve sonuçlar klasik epidemiyolojik verilerle de doğrulanmış-tır 17 . Mengeloğlu ve arkadaşları 18 ise, taşıyıcılardan izole edilen GAS izolatları arasındaki klonal ilişkiyi, %80.4 gibi oldukça yüksek bir oranda bulmuşlardır.…”

Generation of Metabolically Diverse Strains ofStreptococcus pyogenesduring Survival in Stationary Phase

“…Asymptomatic carriage and antibiotic treatment failure suggest that S. pyogenes may be able to persist in the host after the initial infection (5, 7). S. pyogenes asymptomatic carriage rates of 2.5% to 32% have been observed with large cohorts of school-age children worldwide (2,16,23,46,56,57,63,64). Carriage in adults is less frequent (1.3% to 4.9%) but has been observed with adult health care workers and military recruits (9, 34).…”

Carriage of Group A Beta-Hemolytic Streptococci in Preschool Centres

“…(p<0,05) Bu durumun çocukların sosyalleşmeleri ile ilişkili olabileceği Ayrıca aynı ortamı paylaşan kişi sayısının artmasının da bir risk faktörü olabileceği çalışmalarda bildirmiştir. 9 Çalışma-da da hem anne hem de babası kalabalık ortamlarda çalı-şan çocukların taşıyıcılık oranları istatistiksel olarak anlamlı düzeyde yüksek bulunmuştur. Bu sonuç anne ve babanın çalışma ortamının çocuklardaki AGBHS taşıyıcılığı açısın-dan bir risk faktörü olabileceği şeklinde değerlendirilebili-nir.…”