Bacterial biofilm in adenoids of children with chronic otitis media. Part II: a case–control study of nasopharyngeal microbiota, virulence, and resistance of biofilms in adenoids

Abstract

Background: We previously described that adenoid tissue in children with chronic otitis media (COM) contained more mucosal biofilms than adenoid tissue removed for hypertrophy.

Aims/objectives: The aim of the second part was to characterize nasopharyngeal microbiota and explore virulence of the most common middle ear pathogens.

Material and methods: Bacteriological analysis was performed following a culture-based approach on the samples recovered from 30 patients of COM group (15 biofilm-positive and 15 biofilm-negative) and from 30 patients of a control group (15 biofilm-positive and 15 biofilm-negative). Virulence factors of Streptococcus pneumoniae, Streptococcus pyogenes, and Haemophilus influenzae were investigated.

Results: The most frequent species were Firmicutes followed by Proteobacteria and Actinobacteria. The presence of biofilm was statistically associated with an increase of the number of bacterial species and Firmicutes phylum regardless of the condition (case/control). No virulence factors associated with invasive isolates were found for the most common middle ear pathogens.

Conclusions and significance: This case–control study demonstrated that the presence of COM plus biofilm was associated with a given microbiota which contained more Firmicutes. Our study allows a better understanding of physiopathological mechanisms involved in chronic otitis media and paves the way for further investigations.

Chinese abstract

背景：我们以前描述过, 慢性中耳炎（COM）患儿的腺样组织比因肥大而切除的腺样组织含有更多的粘膜生物膜。

目的：第二部分的目的是鉴定鼻咽微生物群, 并探索最常见的中耳病原体的毒力。

材料与方法：采用培养法对COM组30例（15例生物膜阳性；15例生物膜阴性）和对照组30例（15例生物膜阳性；15例生物膜阴性）进行细菌学分析。研究了肺炎链球菌、化脓链球菌和流感嗜血杆菌的毒力因子。

结果：最常见的菌种是厚壁菌, 其次是蛋白菌和放线菌。在统计学上, 生物膜的存在与细菌种类和硬壁菌门的数量的增加有关, 而与病情状态无关（病例/对照）。对于最常见的中耳病原体, 没有发现与侵袭性分离株相关的毒力因子。

结论和意义：本病例对照研究表明, COM加生物膜的存在与含有更多硬壁的特定微生物群有关。我们的研究有助于更好地了解慢性中耳炎的生理病理机制, 为进一步的研究铺平了道路。

Keywords:

• Biofilms
• adenoids
• otitis media
• microbiota
• virulence
• antimicrobial susceptibility

Acknowledgment

The authors thank Pr Jan J Gröte, for his counseling in this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded by APHP, Clinical Research Unit.