Brogan O, Malone J, Fox C, Whyte A S
Department of Microbiology, Fife Area Laboratory, Kirkcaldy.
J Clin Pathol. 1997 Apr;50(4):332-5. doi: 10.1136/jcp.50.4.332.
To evaluate Lancefield grouping and caramel smell for presumptive identification of the Streptococcus milleri group, and to find whether Lancefield group, species, or protein profile correlated with virulence or infection site.
Prospective studies were made of 100 consecutive streptococcal isolates in blood cultures or pus from 100 patients in whom the severity of infection was categorised as serious, moderate, or not significant. The usefulness of Lancefield group and the caramel smell for presumptive identification was examined, and the relation of the S milleri species, Lancefield group, and SDS-PAGE protein analysis to severity of infection and infection site was investigated. Lower respiratory tract and genital tract specimens, strict anaerobes, group D streptococci, and strains identified as Streptococcus pneumoniae, Streptococcus pyogenes, or Streptococcus agalactiae were excluded.
Most streptococci occurring in pure or significant growth density were S milleri group (87/100; 87%, 95% confidence interval 0.81-0.93). Of these, 89.7% (78/87; 0.84-0.96) were associated with infection. Lancefield group F antigen predominated (41/87; 47.1%, 0.38-0.56). Lancefield group F alone or accompanied by the caramel smell had a specificity of 100%, but a sensitivity of only 47.3% for group F alone, and 19.5% for group F accompanied by the caramel smell. There was no significant association between species, Lancefield group, and severity of infection, site of infection, or pathogenicity. SDS-PAGE analysis failed to discriminate between strains.
Neither species nor Lancefield antigen was related to the site of infection. The presence of Lancefield group F antigen alone or accompanied by a caramel smell was a useful indicator for the S milleri group when present, but was too insensitive to use as a screening test. Most streptococci occurring in pure culture or in significant growth density were of clinical importance. Such organisms should be identified to species level to detect the S milleri group.
评估兰斯菲尔德分组及焦糖气味用于米勒链球菌群初步鉴定的效果，并探究兰斯菲尔德分组、菌种或蛋白质谱是否与毒力或感染部位相关。
对100例患者血培养物或脓液中的100株连续链球菌分离株进行前瞻性研究，这些患者的感染严重程度分为严重、中度或不显著。检查兰斯菲尔德分组及焦糖气味用于初步鉴定的实用性，并研究米勒链球菌菌种、兰斯菲尔德分组及十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）蛋白质分析与感染严重程度及感染部位的关系。排除下呼吸道和生殖道标本、严格厌氧菌、D组链球菌以及鉴定为肺炎链球菌、化脓性链球菌或无乳链球菌的菌株。
以纯培养或显著生长密度出现的大多数链球菌为米勒链球菌群（87/100；87%，95%置信区间0.81 - 0.93）。其中，89.7%（78/87；0.84 - 0.96）与感染相关。兰斯菲尔德F组抗原占主导（41/87；47.1%，0.38 - 0.56）。单独的兰斯菲尔德F组或伴有焦糖气味时，特异性为100%，但单独F组的敏感性仅为47.3%，伴有焦糖气味的F组敏感性为19.5%。菌种、兰斯菲尔德分组与感染严重程度、感染部位或致病性之间无显著关联。SDS - PAGE分析未能区分菌株。
菌种和兰斯菲尔德抗原均与感染部位无关。单独存在兰斯菲尔德F组抗原或伴有焦糖气味时，对存在的米勒链球菌群是一个有用的指标，但作为筛查试验过于不敏感。以纯培养或显著生长密度出现的大多数链球菌具有临床重要性。此类微生物应鉴定到种水平以检测米勒链球菌群。
