Coorevits L, Heytens S, Boelens J, Claeys G
Department of Laboratory Medicine, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium.
Department of Family Medicine and Primary Health Care, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
Eur J Clin Microbiol Infect Dis. 2017 Apr;36(4):635-639. doi: 10.1007/s10096-016-2839-x. Epub 2016 Nov 14.
The workup and interpretation of urine cultures is not always clear-cut, especially for midstream samples contaminated with commensals. Standard urine culture (SUC) protocols are designed in favor of growth of uropathogens at the expense of commensals. In selected clinical situations, however, it is essential to trace fastidious or new uropathogens by expanding the urine culture conditions (EUC). The aim of our study was to map the microflora in midstream urine specimens from healthy controls by means of EUC, in view of the interpretation of bacterial culture results in symptomatic patients. Midstream urine specimens from 101 healthy controls (86 females and 15 males) were examined using both SUC and EUC. Whilst 73 % of samples examined by SUC showed no growth at 10 colony-forming units (CFU)/mL, 91 % of samples examined by EUC grew bacterial species in large numbers (≥10 CFU/mL). Asymptomatic bacteriuria, as defined by the European guidelines for urinalysis, was detected in six samples with both protocols. EUC revealed 98 different species, mostly Lactobacillus, Staphylococcus, Streptococcus, and Corynebacterium. None of the samples grew Staphylococcus saprophyticus, Corynebacterium urealyticum, or Aerococcus urinae. Samples from females contained higher bacterial loads and showed higher bacterial diversity compared to males. Midstream urine of healthy controls contains large communities of living bacteria that comprise a resident microflora, only revealed by EUC. Hence, the use of EUC instead of SUC in a routine setting would result in more sensitive but less specific results, requiring critical interpretation. In our view, EUC should be reserved for limited indications.
尿培养的检查和解读并不总是清晰明确的，尤其是对于被共生菌污染的中段尿样本。标准尿培养（SUC）方案旨在促进尿路病原体生长，却不利于共生菌生长。然而，在特定临床情况下，通过扩大尿培养条件（EUC）来追踪苛养菌或新型尿路病原体至关重要。鉴于对有症状患者细菌培养结果的解读，我们研究的目的是通过EUC来描绘健康对照者中段尿标本中的微生物群落。对101名健康对照者（86名女性和15名男性）的中段尿标本同时采用SUC和EUC进行检查。虽然SUC检测的样本中有73%在10菌落形成单位（CFU）/mL时无细菌生长，但EUC检测的样本中有91%大量生长细菌（≥10 CFU/mL）。两种方案在六个样本中均检测到了欧洲尿液分析指南所定义的无症状菌尿。EUC显示有98种不同的细菌，主要是乳酸杆菌、葡萄球菌、链球菌和棒状杆菌。没有样本培养出腐生葡萄球菌、解脲棒状杆菌或尿液气球菌。与男性相比，女性样本中的细菌载量更高，细菌多样性也更高。健康对照者的中段尿中含有大量活细菌群落，构成了一个常驻微生物群落，只有通过EUC才能揭示。因此，在常规情况下使用EUC而非SUC会得到更敏感但特异性更低的结果，这需要审慎解读。我们认为，EUC应仅用于有限的适应症。
