Ability of urethral discharge to predict UTI
Among the 678 children in our cohort, 544 were diagnosed with UTI, and 134 did not fulfill the diagnostic criteria. Thirty-eight children presented with urethral discharge, and among them, 28 were diagnosed with UTI. The urethral discharge mostly presented as yellowish or greenish sticky pus on the diaper or genital area. It could be a faint stain on the diaper, making it difficult to observe, and sometimes, the discharge was observed on wiping tissue during a diaper change. (figure1). Gram stains of urethral discharge revealed mucus-like substances with some leukocytes and bacteria, implying an inflammation process related to bacteria (figure 2).The sensitivity and specificity of urethral discharge for predicting UTI were 5.1% and 92.5%, respectively, and the positive and negative predictive values of urethral discharge for predicting UTI were 73.7% and 19.4%, respectively.
Children with UTI presenting with and without urethral discharge
Among 544 children with UTI, 28(5.1%) presented with urethral discharge. The mean age of the cohort was 5.8±5.0 months old, 342(63%) of whom were male. The two groups were comparable in body height and weight. (Table 1)
Table 1
Characteristics of UTI children presenting with and without urethral discharge.
Variables | Total n=544 (%) | UTI with urethral discharge n=28 (%) | UTI without urethral discharge n=516 (%) | p-value |
Age, months, mean(±SD) | 5.8(±5.0) | 5.6(±3.7) | 5.8(±5.1) | 0.809 |
Male, n (%) | 342(63) | 13(46) | 329(64) | 0.065 |
Body height, mean(±SD) | 65.4(±9.1) | 65.6(±7.4) | 65.4(±9.2) | 0.917 |
Body weight, mean(±SD) | 7.4(±2.1) | 7.7(±1.7) | 7.4(±2.1) | 0.578 |
Clinical manifestations | | | | |
Bacteremia, n (%) | 12(2) | 0(0) | 12(2) | 1.000 |
Vomit, n (%) | 69(13) | 6(21) | 63(12) | 0.150 |
Foul odor urine, n (%) | 81(15) | 14(50) | 67(13) | <0.001 |
Gross hematuria, n (%) | 20(4) | 3(11) | 17(3) | 0.077 |
Fever days before treatment (day), mean(±SD) | 1.5(±1.3) | 1(±1.4) | 1.5(±1.3) | 0.028 |
Days before defervescence (day), mean(±SD) | 1.3(±1.2) | 0.93(±1.1) | 1.3(±1.2) | 0.084 |
Received treatment before fever, n (%) | 28(5) | 9(32) | 19(4) | <0.001 |
Fever > 39°C, n (%) | 298(55) | 5(18) | 293(57) | <0.001 |
Urine | | | | |
Positive nitrite, n (%) | 213(39) | 11(39) | 202(39) | 0.988 |
Leukocyte esterase | | | | 1.000 |
Negative, n (%) | 12(2) | 0(0) | 12(2) | |
1~2+, n (%) | 77(14) | 4(14) | 73(14) | |
3+, n (%) | 455(84) | 24(86) | 431(84) | |
Gram stain | | | | 0.132 |
Negative, n (%) | 58(11) | 6(2) | 52(10) | |
Few, n (%) | 224(41) | 9(32) | 215(42) | |
Many, n (%) | 262(48) | 13(46) | 249(48) | |
RBC (/hpf) | | | | 0.913 |
<5, n (%) | 340(63) | 18(64) | 322(62) | |
5~49, n (%) | 180(33) | 9(32) | 171(33) | |
50~99, n (%) | 15(3) | 1(4) | 14(3) | |
>100, n (%) | 9(2) | 0(0) | 9(2) | |
Uropathogen | | | | |
E. Coli, n (%) | 482(89) | 19(68) | 463(90) | 0.002 |
K. pneumoniae, n (%) | 24(4) | 5(18) | 19(4) | 0.005 |
Proteus spp, n (%) | 16(3) | 2(7) | 14(3) | 0.197 |
ESBL E.Coli, n (%) | 194(36) | 9(32) | 185(36) | 0.534 |
Abbreviations: ESBL: extended spectrum beta lactamase. HPF: high power field. RBC: red blood cell. SD: standard deviation. UTI: urinary tract infection. |
Children with urethral discharge were more likely to present with malodorous urine than those without urethral discharge (50% and 13%, respectively, P< 0.001); they were also more likely to have gross hematuria, although this association was not statistically significant (11% and 3%, respectively; P = 0.077). No differences were observed in the rate of vomiting or bacteremia between the two groups.
Children with urethral discharge had a lower rate of high fever than those without urethral discharge (18% and 57%, respectively;P< 0.001), and the number of days children had fevers before receiving treatment was lower. Nine children (32%) who presented with urethral discharge received antibiotics before fever onset; seven did not develop a fever during the entire UTI treatment course; and two developed a fever after treatment, but defervescence occurred within 1 day. Nonetheless, the days before defervescence after treatment initiation were similar between the two groups (0.93 and 1.3 days, respectively, P = 0.084).
Overall, 98% and 89% of children with UTI were positive for leukocyte esterase and bacteria in urinalysis, and the rate was similar in the two groups. Thirty-nine percent of children with UTI were positive for nitrite, and 38% were positive for urine RBC; no differences were observed in these rates between the two groups.
Uropathogens in children with UTI presenting with urethral discharge
In total, 482 (89%) of UTIs were caused by Escherichia coli; however, E. coli was less prevalent in children with urethral discharge compared with those without urethral discharge (68% and 90%, respectively;P = 0.002). A higher rateof Klebsiella pneumonia infection was observed in children with urethral discharge than in those without urethral discharge. No difference was observed in the rate of Proteus spp. or ESBL-producing E.Coli between the two groups.
Clinical variables associated with UTI children with urethral discharge
Multivariate forward logistic regression revealed that malodorous urine, infection with K. pneumonia, and receiving treatment before fever onset were the factors that were most strongly associated with UTI presenting urethral discharge (adjusted odds ratios [aORs]: 4.79 (1.98–11.6), 9.73 (2.64–35.84), and 9.19 (3.1–27.2), respectively). A fever that spiked above 39°C and male gender were less strongly associated with UTI with urethral discharge (Table 2).
Table 2
Clinical variables related to UTI in children presenting with urethral discharge.
Variables | OR (95% CI) | p-value | aOR (95% CI) | p-value |
Age, months | 0.99 (0.92~1.07) | 0.808 | | |
Male | 0.49 (0.23~1.06) | 0.069 | 0.37 (0.15~0.90) | 0.028 |
Body height | 1.00 (0.96~1.05) | 0.917 | | |
Body weight | 1.05 (0.88~1.26) | 0.578 | | |
Clinical manifestations | | | | |
Bacteremia | 0.71 (0.04~12.26)* | 0.813 | | |
Vomit | 1.96 (0.77~5.02) | 0.160 | | |
Foul odor urine | 6.70 (3.06~14.68) | <0.001 | 4.79 (1.98~11.6) | 0.001 |
Gross hematuria | 3.52 (0.97~12.81) | 0.056 | | |
Fever days before treatment | 0.46 (0.24~0.90) | 0.024 | | |
Days before defervescence | 0.78 (0.59~1.03) | 0.084 | | |
Received treatment before fever | 12.39 (4.96~31.00) | <0.001 | 9.19 (3.10~27.20) | <0.001 |
Fever > 39°C | 0.17 (0.06~0.44) | <0.001 | 0.23 (0.08~0.70) | 0.009 |
Urine | | | | |
Positive nitrite | 1.01 (0.46~2.19) | 0.988 | | |
Leukocyte esterase | | | | |
Negative | | | | |
1~2+ | 1.01 (0.34~3.00) | 0.984 | | |
3+ | 1.18 (0.40~3.50) | 0.761 | | |
Gram stain | | | | |
Negative | | | | |
Few | 0.66 (0.29~1.46) | 0.322 | | |
Many | 0.93 (0.43~1.99) | 0.851 | | |
RBC (/hpf) | | | | |
<5 | | | | |
5~49 | 0.96 (0.42~2.16) | 0.913 | | |
50~99 | 1.33 (0.17~10.48) | 0.788 | | |
>100 | 0.94 (0.05~16.5)* | 0.965 | | |
Uropathogen | | | | |
E. Coli | 0.24 (0.10~0.56) | 0.001 | | |
K. pneumoniae | 5.69 (1.95~16.58) | 0.001 | 9.73 (2.64~35.84) | 0.001 |
Proteus spp | 2.76 (0.60~12.78) | 0.195 | | |
ESBL E.Coli | | 0.534 | | |
*Adjusted with Haldane correction . |
Abbreviations: aOR: adjusted odds ratio. ESBL: extended spectrum beta lactamase. HPF: high power field. OR: odds ratio. RBC: red blood cell. SD: standard deviation. UTI: urinary tract infection. |
Urine characteristic associated with urethral discharge
Urine biochemistry was available for 672 children, 37 of whom presented with urethral discharge. The urine specific gravity, protein, sugar, ketone bodies, occult blood were comparable in both groups, but a higher urine PH value was observed in children with urethral discharge. No difference in the positive nitrite rate or the leukocyte esterase rate was observed (Table 3).
Table 3
Urinalysis of children presenting with and without urethral discharge.
Variables | Total n=672(%) | with urethral discharge n=37 (%) | without urethral discharge n=635 (%) | p-value |
Specific gravity≤1.015 | 606(90) | 35(95) | 571(90) | 0.568 |
pH≧7.0 | 202(30) | 20(54) | 182(29) | 0.001 |
Positive protein | 407(61) | 19(51) | 388(61) | 0.299 |
Positive sugar | 24(4) | 0(0) | 24(4) | 0.636 |
Positive ketone bodies | 86(13) | 1(3) | 85(13) | 0.073 |
Positive occult blood | 440(66) | 22(60) | 418(66) | 0.478 |
Positive nitrite | 226(34) | 11(30) | 215(34) | 0.721 |
Positive leukocyte esterase | 624(93) | 35(95) | 589(93) | 1.000 |