Indian Journal of Medical Microbiology Home 

Year : 2002  |  Volume : 20  |  Issue : 2  |  Page : 105--106

Asymptomatic bacteriuria in antenatal women

SV Lavanya, D Jogalakshmi 
 Dept. of Microbiology, Andhra Medical College, Visakhapatnam - 530 002, India

Correspondence Address:
S V Lavanya
Dept. of Microbiology, Andhra Medical College, Visakhapatnam - 530 002


A total of 500 antenatal women in their first or second trimesters were screened over a period of 2 years for asymptomatic bacteriuria. Out of them, 8.4% (42) were culture positive. A control group of 100 non-pregnant women, both married and unmarried, was also simultaneously screened. The control group yielded an overall culture positivity of 3% (4% in the married non-pregnant women and 2% in the unmarried women). Primigravida had highest percent culture positivity of 66.6%. The incidence was higher in less than 20 years age group i.e. 71.42%. Of the screening tests, Gram stained smear when compared with the standard loop method, showed the highest sensitivity of 95.2%. The specificity of the screening tests was high [Gram stained smear (98.6%), catalase test (97.1%) and pus cell count(96.5%)]. Escherichia coli was the most common organism isolated in the test and control groups. The organisms were sensitive to cephalexin, nitrofurantoin, amoxycillin and norfloxacin in decreasing order. Incidence of prematurity was 75% and that of low birth weight was 50% in untreated patients.

How to cite this article:
Lavanya S V, Jogalakshmi D. Asymptomatic bacteriuria in antenatal women.Indian J Med Microbiol 2002;20:105-106

How to cite this URL:
Lavanya S V, Jogalakshmi D. Asymptomatic bacteriuria in antenatal women. Indian J Med Microbiol [serial online] 2002 [cited 2020 Jul 9 ];20:105-106
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Full Text

Urinary tract is second only to the respiratory tract in acquiring microbial infection, especially in females. It is more common in pregnant than in non-pregnant women.1,2 Studies from different parts of India have indicated that urinary tract infection(UTI) during pregnancy leads to low birth weight babies, increased perinatal mortality and premature births along with acute and chronic sequelae in mothers.[3] This study was conducted to explore different aspects of UTI during pregnancy.

 Materials and Methods

Material for the present study consisted of 500 urine samples obtained from asymptomatic antenatal mothers in their first or second trimesters. The study group consisted of patients from in and around Visakhapatnam, attending as out patients of Obstetric department of King George Hospital, Visakhapatnam, during the years 1997 to 1999.

Data was collected on a predesigned proforma, and patients were instructed to collect only mid stream sample of urine into sterile bottles. These were transported within half an hour to the laboratory and processed without delay. The control group consisted of 50 unmarried women and 50 married women below 30 years of age.

Each of the specimens were subjected to culture by the standard loop technique on blood agar, MacConkey's agar and nutrient agar. The specimens were processed by screening methods namely a) counting of pus cells in the uncentrifuged urine using slide micrometry method (a value of 10 cells/cumm or more corresponds to pyuria and signifies the presene of UTI); b) Gram staining of the urine smear by Jensen's modification (presence of at least one organism per oil immersion field was taken to correlate with significant bacteriuria of more than 10 cfu/cumm, discarding as negative after examining at least 20 fields); c) Triphenyl Tetrazolium Chloride (TTC) Test: Reduction of triphenyl tetrazolium chloride to a red precipitate of triphenyl formazan takes place only at an alkaline pH. Such a pH in urine prevails only during a urinary tract infection; and d) Catalase Test: Presence of catalase enzyme evidenced by frothing on addition of a few drops of hydrogen peroxide to a 2mL sample of urine.

All the specimens that yielded positive results by any one of the above four screening methods were subjected to culture by the pour plate method.Colonies were counted from plates which showed between 50 and 400 colonies per plate. Colonies were counted on a colony counter. The specimens were classified into significant with counts being those equal to or more than 105 cfu/mL. The significant bacterial isolates were identified by standard procedures and subjected to antibiotic susceptibility by disc diffusion method.

Patients yielding a positive culture for a second time by the same organism were advised antibiotic treatment. Cultures were repeated after a three day course to make sure that the infection was controlled. Perinatal outcome of all the patients was followed.


Out of the 500 antenatal mothers screened, 42 (8.4%) were culture positive. 28 (66.6%) of the cases were primigravida, 3 (7.2%) were first para, 4 (9.6%) were second para and 7 (16.6%) were multiparous. This study revealed that incidence increased as socio economic status of the patients decreased and a higher incidence was recorded in patients of lower age group. Incidence of culture positivity was 1/50 (2%) in unmarried women, and 2/50(4%) in married non pregnant women. There were 2 cases (66.6%) in the less than Rs.1000/- income group, none in Rs.1000/- to 2000/- and Rs.2000/- to 3000/- income group, and 1 case (33.3%) in the Rs.3000/- income group. The sensitivity and specificity of the screening methods when compared with calibrated loop method are given in the [Table:1].

Numbers and percentages of the various pathogenic organisms isolated from pregnant women is depicted in [Table:2]. Escherichia coli was the only organism isolated in the control group.

Thirty eight cases (90.46%) complied with treatment and 4 (9.54%) did not. Three out of four (75%) who did not take treatment delivered prematurely and two (50%) delivered low birth weight babies.


Causative agents of asymptomatic bacteriuria in females are usually the commensal bacteria of the female genital tract and of the bowel. Different determinants of virulence such as presence of adhesins, stasis produced by gravid uterus etc. play a role in the causation of UTI.

Review of literature revealed an incidence varying from 4% to 23.9% in studies conducted by various workers.[1] The incidence of 8.4% in the present study is quite close to that of the earlier workers. Our finding of a higher incidence in primis and in those below 25 years of age correlated with those of two other workers.[2] [Table:3]

In the present study, in agreement with many other similar studies,[1] E.coli was the most common organism isolated, followed by Klebsiella and Staphylococcus aureus.

Our findings regarding perinatal complications in patients with asymptomatic bacteriuria confirm the conclusion of Mittendorf et al[3] who showed significant bacteriuria in preterm group and term group of 36% and 12% respectively.


1Kriplani A, Bukshee K, Ratan A. Asymptomatic bacteriuria in pregnant Indian patients at All India Institute of Medical Sciences, New Delhi, and Treatment with single dose antimicrobial therapy. J of Obst Gyn of India 1993; 43:489-491.
2Sharma JB, et al. Prevalence of significant bacteriuria in preterm labour. J of Obst Gyn of India 1990; 40:336-338.
3Mittendorf R, Williams MA, Kass EH. Prevention of preterm delivery and low birth weight associated with asymptomatic bacteriuria. Clin Infect Dis 1992; 14:927-32.