導尿管更換前後對尿液常規及尿液培養結果之影響

Influence of Urethral Catheter Replacement on Urinalysis and Urine Cultures

本研究的目的在探討某醫學中心成人加護病房導尿管留置病人，於導尿管更換前、後對尿液常規及尿液培養檢驗結果的影響。自2006年1月至2007年8月期間，針對發燒疑似泌尿道感染而更換導尿管之病人為研究對象，於導尿管更換前、後，分別各採檢一套尿液常規及尿液培養檢體。尿液常規分析包括感染相關指標白血球脂酶、亞硝酸鹽及白血球計數；尿液培養陽性者則進行菌種鑑定及藥物敏感性試驗。結果顯示導尿管更換後，亞硝酸鹽陽性率和菌尿陽性率明顯下降（p＜0.05）。雖然導尿管更換前、後的菌種種類和菌株數分布沒有顯著差異，但在陽性檢體中，仍有41.9%的成對檢體分離出不一致的菌種。當篩檢真正菌尿時，則以導尿管更換後之膿尿指標、導尿管更換前或後之合併白血球脂酶、亞硝酸鹽或膿尿三項指標及導尿管更換前之菌尿指標的敏感度最高，皆為94.1%。建議疑似發生泌尿道感染時，可以導尿管更換前之尿液常規三項合併指標篩檢真正菌尿，並依據臨床症狀留取尿液培養檢體。在確認致病菌前，為排除生物膜的影響，應先更換導尿管再收集尿液培養檢體。

This study was designed to evaluate the impact of urethral catheter replacement on urinalyses and urine cultures. Eighty-one patients from adult intensive care units of a medical center in Taiwan were enrolled in this study. These patients were suspected of having a urinary tract infection, and a change of the urethral catheter had been suggested for them. Paired urine specimens were collected under aseptic conditions before and after the catheter replacements. The results were positive, suggesting that the levels of nitrite and rates of bacteriuria significantly decreased after catheter replacements. The distribution of species and strains were not significantly different among patients. However, inconsistent organisms were isolated from 42% of positive paired specimens. Organisms isolated from the paired urine cultures showed identical antibiograms. The screening parameters for pyuria after catheter replacements and the combined parameters of leukocyte esterase, nitrite, and pyuria before and after catheter replacements and bacteriuria before catheter replacements showed the highest sensitivity of 94.1% for bacteriuria. To identify the organism involved in urinary tract infections of these patients, we suggest collecting urine culture specimens after catheter replacements.