直接接种法与肉汤增菌培养法用于检测呼吸道分泌物中潜在细菌病原体的比较。

Comparison of direct-plating and broth-enrichment culture methods for detection of potential bacterial pathogens in respiratory secretions.

作者信息

Kaur Ravinder, Wischmeyer Jareth, Morris Matthew, Pichichero Michael E

机构信息

Rochester General Hospital Research Institute, Center for Infectious Diseases and Immunology, 1425 Portland Avenue, Rochester, NY 14621, USA.

出版信息

J Med Microbiol. 2017 Nov;66(11):1539-1544. doi: 10.1099/jmm.0.000587. Epub 2017 Oct 16.

DOI:10.1099/jmm.0.000587

PMID:29034852

Abstract

OBJECTIVE

We compared the recovery of potential respiratory bacterial pathogens and normal flora from nasopharyngeal specimens collected from children during health and at the onset of acute otitis media (AOM) by selective direct-plating and overnight broth-enrichment.

METHODS

Overall, 3442 nasal wash (NW) samples collected from young children were analysed from a 10-year prospective study. NWs were cultured by (1) direct-plating to TSAII/5 % sheep blood agar and chocolate agar plates and (2) overnight broth-enrichment in BacT/ALERT SA-broth followed by plating. Standard microbiology techniques were applied to identify three dominant respiratory bacterial pathogens: Streptococcus pneumoniae (Spn), Haemophilus influenzae (Hflu) and Moraxella catarrhalis (Mcat) as well as two common nasal flora, Staphylococcus aureus (SA) and alpha-haemolytic Streptococci (AHS).Results/Key findings. Direct-plating of NW resulted in isolation of Spn from 37.8 %, Hflu from 13.6 % and Mcat from 33.2 % of samples. In comparison, overnight broth-enrichment isolated fewer Spn (30.1 %), Hflu (6.2 %) and Mcat (16.2 %) (P<0.001-0.0001). Broth-enrichment resulted in significant increased isolation of SA (6.0 %) and AHS (30.1 %) (P<0.0001). Competition between bacterial species in broth when both species were detected by direct-plating was assessed, and it was found that SA and AHS out-competed other species during broth-enrichment when samples were collected from healthy children but not during AOM. In middle ear fluids (MEF) at the onset of AOM, broth-enrichment resulted in higher recovery of Spn (+10.4 %, P<0.001), Hflu (+4.4 %, P=0.39) and Mcat (+13.5 %, <0.001).

CONCLUSION

Broth-enrichment significantly reduces the accurate detection of bacterial respiratory pathogens and increases identification of SA and AHS in NW. Broth-enrichment improves detection of bacterial respiratory pathogens in MEF samples.

摘要

目的

我们通过选择性直接接种平板法和过夜肉汤增菌法，比较了健康儿童和急性中耳炎（AOM）发病时从鼻咽部标本中分离潜在呼吸道细菌病原体和正常菌群的情况。

方法

在一项为期10年的前瞻性研究中，共分析了从幼儿采集的3442份洗鼻（NW）样本。NW样本通过以下两种方法培养：（1）直接接种到TSAII/5%羊血琼脂平板和巧克力琼脂平板上；（2）在BacT/ALERT SA肉汤中过夜增菌后再接种平板。采用标准微生物学技术鉴定三种主要呼吸道细菌病原体：肺炎链球菌（Spn）、流感嗜血杆菌（Hflu）和卡他莫拉菌（Mcat），以及两种常见鼻内菌群：金黄色葡萄球菌（SA）和甲型溶血性链球菌（AHS）。结果/主要发现。NW样本直接接种平板法分离出Spn的样本占37.8%，Hflu占13.6%，Mcat占33.2%。相比之下，过夜肉汤增菌法分离出的Spn（30.1%）、Hflu（6.2%）和Mcat（16.2%）较少（P<0.001 - 0.0001）。肉汤增菌法使SA（6.0%）和AHS（30.1%）的分离率显著增加（P<0.0001）。评估了直接接种平板法检测到两种细菌时肉汤中细菌之间的竞争情况，发现从健康儿童采集样本时，SA和AHS在肉汤增菌过程中比其他细菌更具竞争力，但在AOM发病时并非如此。在AOM发病时的中耳积液（MEF）中，肉汤增菌法使Spn的回收率更高（+10.4%，P<0.001），Hflu更高（+4.4%，P = 0.39），Mcat更高（+13.5%，<0.001）。