尿常规及尿液有形成分分析在尿路感染诊断中的初筛价值研究

Evaluation of preliminary screening performance of routine urinalysis and quantitative analysis for urinary formed elements in diagnosis of urinary tract infection

目的通过尿常规、尿液有形成分分析与尿细菌培养结果,研究尿常规相关指标在尿路感染诊断中的应用价值。方法回顾性分析2014年1月1日-2015年12月31日1 534例同时送检尿常规(尿常规+尿液有形成分分析)与清洁中段尿细菌培养的门诊及住院患者结果,分析尿培养阳性率及菌种分布,并以尿培养结果作为金标准,分析尿常规和有形成分分析中与尿路感染相关指标对尿路感染的诊断性能。结果 1 534例患者标本中,778例(50.7%)尿培养结果为"普通培养经鉴定无细菌生长";尿培养阳性患者468例(30.5%),尿培养阳性菌中,革兰阴性菌最多占57.48%,革兰阳性菌次之占38.46%,真菌最少占4.06%;分析尿路感染相关指标的诊断性能,可见亚硝酸盐(NIT)的诊断比值比(DOR)最高,说明NIT结果与尿培养结果的联系程度最大,此外,LEU、Bacteriuria、WBC的诊断比值比也都>1,与尿培养结果的联系程度也较大,对于尿路感染的诊断,灵敏度最高的为干化学中性粒细胞酯酶(LEU),特异性最高的是NIT(>95%),尿液有形成分WBC计数结果用于诊断尿路感染的特异性均>80%,尿液有形成分Bacteriuria计数结果用于诊断尿路感染的特异性>80%(除外60岁以上人群),NIT用于诊断尿路感染的阳性预测值(PPV)最高约80%,用于排除尿路感染,LEU的阴性预测值(NPV)>80%,其次为NIT。结论大多数尿培养为阴性或可疑污染,尿常规NIT、LEU以及尿液有形成分分析WBC、Bacteriuria计数作为一种快速筛查实验,对于排除尿路感染、减少不必要的尿培养有着重要的临床应用价值。

OBJECTIVE To evaluate the preliminary screening value of routine urinalysis and quantitative analysis for urinary formed elements in the diagnosis of urinary tract infection. METHODS A totally of 1534 cases which were performed urine routine （or urine routine and quantitative analysis for urinary formed elements） and the mid- stream urine bacterial culture for outpatients and hospitalization patients from Jan. 1st, 2014 to Dec. 31st, 2015 were retrospectively analyzed. The positive rate of urine culture and the distribution of bacteria were analyzed, and the performance of the various indexes in screening urinary tract infection was evaluated with the bacterial culture results as the golden standard. RESULTS In 1534 cases of patients, 778 cases（50.7 %） were negative of urine cul- ture, and 468 cases（30. 5%） had positive urine culture results. Among positive cases, the composition ratio of gram-negative bacteria, gram-positive bacteria and fungi were 57.48%, 38.46% and 4.06%, respectively. Evalu- ating the performance of the various indexes in screening urinary tract infection, NIT had the highest DOR, which meant the greatest relationships between NIT and urine culture. The DOR of LEU, Bacteriuria, WBC were 〉1, a relatively correlation was determined between LEU, Bacteriuria, WBC and urine culture. The highest specificity rate was estimated for NIT（〉95 % ）, the specificity of WBC counts was greater than 80 % ,and the specificity of Bacteriuria was greater than 80 % （except for the group more than 60 years old） . Diagnosis of a UTI, NIT had the highest positive predictive value（about 80 %）, ruling out UTI, and the negative predictive value of LEU was more than 80%, followed by NIT. CONCLUSION Considering that most samples from the patients in our study have insignificant or no growth, rapid urine analysis of NIT, LEU and WBC, Bacteriuria counts can rule out UTI in these patients, which can reduce unnecessary culture requests in the clinical practice.