Urinary Tract Infection in Pregnancy and its Correlation with Nitrite Test

Background: Urinary Tract Infection is one of the most frequently seen medical complications of pregnant women. The value of screening for bacteriuria by rapid test has to be readdressed considering methods, significance and costs. The study was done to assess the sensitivity and specificity of rapid test (nitrite test) for the confirmation of UTI and etiology of infection during pregnancy and antibiotics sensitivity pattern of the isolates.


INTRODUCTION
Urinary Tract Infection (UTI) is one of the most frequently encountered problems owing to significant number of patients needing hospitalization during pregnancy.In pregnant women the incidence of UTI can be as high as 8%.Similarly, 2% of 24000 patients acquired acute pyelonephritis during pregnancy. 1The report has shown that 6% of pregnant women had asymptomatic bacteriuria as well as 11.8% of bacteriuric women developed symptoms of infection in pregnancy; whereas only 3.2% of women with sterile urine did so. 2,3e diagnosis of UTIs should be based initially on the clinical aspects presented by the patient and confirmed by urine culture.However, microscopic examination of urine for the presence of pyuria with nitrite test is another available option for the rapid screening of UTI.The nitrite test is highly sensitive and specific when properly used in first morning urines whose efficiency was found to 90 %. 4 Thus, A positive nitrite test with pyura is taken as highly reliable marker for bacterial UTI.
Escherichia coli is present in between 80 and 90% of UTIs and up to 95% of acute pyelonephritis 5,6 and Novobiocinresistant Staphylococcus saprophyticus is the true gram positive pathogen of UTI. 7 This article briefly examines the efficiency of nitrite test for UTI with culture, significant of pus cells, etiological agents for UTI in pregnant women and their antibiotic sensitivity pattern.

METHODS
An observational study was conducted in Lumbini Zonal Hospital from October 2004 to March 2005.Ethical approval was taken from institutional ethical committee.Similarly, Verbal consent was taken to all patients for fulfilling semi structured interview questionnaire.Purposive sample were selected on the basis of symptoms of increased frequency micturation, Dysurea, Uregency and Fever in clinically suspected UTI patient.All clinically suspected pregnant women of UTI, attending outpatient department and hospitalized were only included where as non pregnant women were excluded.
Mid stream urine was processed for nitrate reduction test, microscopy for pyuria, and culture.Urine culture, WBC counts and nitrite test were performed on the urine specimen.Nitrite test was performed by using two drops of two different solutions; N-1-napthylenediamine and sulphanilamide and mixed with equal amounts of urine in a kit well and observed for magenta color for positive test.
For culture, 0.001 ml of un-centrifuged, mixed mid stream urine specimen were streaked onto Mac-Conkey agar and Blood agar plates with the help of standard flame sterilized loop.Bacterial growths were observed following overnight incubation and their sensitivity pattern were determined by Kirby-Bauer disc diffusion method.Finally, correlation between nitrite test and bacterial isolates were determined.
Statistical analysis was done by in accordance with the specific objective i.e. finding sensitivity, specificity and positive and negative predictive values of nitrite and culture.For this Microsoft excel was used.

RESULTS
Out of 100 clinically suspected pregnant women of UTI cases having different ages, 45 (45%) were culture positive.Of that culture positive cases, age 20-30, were the highest number suffered from UTI (Table 1).Of the total suspected cases, the majority 59 (59%) cases were multigravidae and that was the highest number suffered from UTI, 27 (60%) in positive cases.72% of the clinically suspected patients had increased frequency of micturition of which 22 (30.5%) were culture positive.Based on different symptoms different diagnosed cases were found (Table 2).Of the total suspected cases, 83.1% were urine culture positive and had pus cell counts (1-5/HPF).However,

Urinary Tract Infection in Pregnancy and Its Correlation with Nitrite Test
cases which have more than 5 pus cells/HPF were all culture positives (Table 3).Samples which showed Nitrite test positive i.e. 17 (37.7%)were all culture positives i.e. if the patient has nitrite positive result, it was sure that his urine was infected with Gram negative bacteria.This shows the positive relationship exists between the Nitrite test and culture positive for the member of enterobacteriaceae family (Table 4 and 5).Of nine antibiotics used in vitro sensitivity test, Amikacin was the most effective followed by others (Figure 1).

Figure 1. Antibiotics sensitivity test for all diagnosed cases
Amikacin was highly effective against Gram-negative bacteria followed by other antibiotics.Similarly, Gentamycin was highly effective against Gram positive followed by other antibiotics (Figure 2).Of the E. coli isolates, 64.2% were effective to Amikacin, followed by other antibiotics.Similarly, Gentamycin was the most effective i.e. 20 (100%) towards Staphylococcus aureus followed by other antibiotics (Figure 3).by culture method the combination of Nitrite test with pyuria appears to be very useful markers for bacterial UTI and is more useful in district laboratories where culture facilities are rare.Since, antibiotics resistant bacterial pathogens were isolated, it can recommend that over use, under use & misuse of antibiotics must be prohibited.On the basis of in vitro tests Ampicillin was found resistant towards bacterial isolates so it should not be used for the treatment of UTI.

Figure 2 .
Figure 2. Antibitics sensitivity and resistant pattern of Gram negative and Gram positive bacteria

Figure 3 .
Figure 3. Antibiotics Sensitivity of E.coli and Staph.aureus

Table 1 .
Distribution of Cases according to Age

Table 3 .
Relation with Pus cells and Positive Culture Results

Table 4 .
Comparison between the results of Nitrite test and Culture Culture positive

Table 5 .
Nitrite test in relation to Enterobacteriaceae and E. coli