Observation in effect of perineal cleansing with sterile water on reduction of the false negative rate of mid-stream urine culture

Abstract

Objective To compare the effect of perineal cleansing with the potassium permanganate or sterile water on mid- stream urine culture. Methods Mid- stream specimens of urine were obtained from inpatients in our hospital between January 2002 and December 2006. All these patients may be diag-nosed as urinary tract infection. The urine specimens were divided into the potassium permanganate group (n=1572, the sterilization group) and the sterile water group (n=544). The change of positive and contami-nation rate of mid-stream urine culture from the specimens was observed. More than two kinds of germs in one urine specimen were defined as contamination. Results 830 patients with urinary tract infection had been enrolled. 2116 specimens were collected and 531 strains of causative organism were detected. The positive rate of the sterilization group and the sterile water group was 20.04% and 39.71%, respectively,and such difference was significant. The rate of identical causative organism from the same patient whose spec-imen was cultivated twice in the sterilization group was 0.012% and the rate was 0.105% in the sterile water group. The difference was significant. The rate of different or one kind of causative organism from the same patient whose specimen was cultivated twice in these two groups hadn't significant deviation. The contami-nation rate of the sterilization group (0.028%) was significantly higher than that of the sterile water group (0.007%). Conclusions Perineal cleansing with sterile water can reduce the false negative rate of mid-stream urine culture without increasing the contamination rate. Potassium permanganate sterilization is re-sponsible for the high false-negative in mid-stream urine culture. Key words: Mid-stream urine culture; Antiseptic; Sterile water; , Perineal cleansing; Positive rate