Abstract
The pharyngeal mucosa can be colonized with bacteria that have potential to cause pharyngotonsillitis. By the use of culturing techniques and PCR, we aimed to assess the prevalence of bacterial pharyngeal pathogens among healthy adolescents and young adults. We performed a cross-sectional study in a community-based cohort of 217 healthy individuals between 16 and 25 years of age. Samples were analyzed for Group A streptococci (GAS), Group C/G streptococci (SDSE), Fusobacterium necrophorum, and Arcanobacterium haemolyticum. Compared to culturing, the PCR method resulted in more frequent detection, albeit in most cases with low levels of DNA, of GAS (20/217 vs. 5/217; p < 0.01) and F. necrophorum (20/217 vs. 8/217; p < 0.01). Culturing and PCR yielded similar rates of SDSE detection (14/217 vs. 12/217; p = 0.73). Arcanobacterium haemolyticum was rarely detected (3/217), and only by PCR. Overall, in 25.3% (55/217) of these healthy adolescents and young adults at least one of these pathogens was detected, a rate that is higher than previously described. Further studies are needed before clinical adoption of PCR-based detection methods for pharyngeal bacterial pathogens, as our findings suggest a high incidence of asymptomatic carriage among adolescents and young adults without throat infections.
Highlights
Streptococcus pyogenes (Group A streptococci; GAS) and Streptococcus dysgalactiae subsp. equisimilis (SDSE; referred to as group C and G streptococci) have been regarded as the primary pharyngeal pathogens [1], with Arcanobacterium haemolyticum sometimes regarded as a pharyngeal pathogen [2]
Real-time PCR assays for SDSE, A. haemolyticum, and F. necrophorum were reactive for all tested target species, and non-reactive for all other tested bacterial strains (Tables S2–S5)
In silico specificity screening revealed that the SDSE assay would likely detect the animal pathogen S. dysgalactiae subspecies dysgalactiae (SDSD), as there were only minor mismatches of the amplifying primers and a perfect match with the probe
Summary
Streptococcus pyogenes (Group A streptococci; GAS) and Streptococcus dysgalactiae subsp. equisimilis (SDSE; referred to as group C and G streptococci) have been regarded as the primary pharyngeal pathogens [1], with Arcanobacterium haemolyticum sometimes regarded as a pharyngeal pathogen [2]. Streptococcus pyogenes (Group A streptococci; GAS) and Streptococcus dysgalactiae subsp. Equisimilis (SDSE; referred to as group C and G streptococci) have been regarded as the primary pharyngeal pathogens [1], with Arcanobacterium haemolyticum sometimes regarded as a pharyngeal pathogen [2]. Fusobacterium necrophorum has been established as a pathogen present in pharyngotonsillitis [3,4,5,6,7]. In a systematic review of F. necrophorum-positive acute tonsillitis, patients showed higher rates of detection than asymptomatic controls, and detection of F. necrophorum. In this review use of PCR methods versus culture methods showed no difference in detection of F. necrophorum either among pharyngotonsillitis patients or asymptomatic controls. As none of the reviewed studies included usage of several detection methods for Fusobacterium necrophorum, a more direct comparison of methodology was not possible
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