1. Dr. Mona Taher Aseel, MBBS, ABFM
Specialist in Family Medicine
Primary Health Care -Qatar
Email: drmona222@hotmail.com

2. Dr. Fathiya Mohamed Al-Meer, MBBS, ABFM
Specialist in Family Medicine
Primary Health Care -Qatar
Email: dr.fathiya@yahoo.com

3. Dr. Mohamed Ghaith Al-Kuwari, MBBS, ABCM, FPHM
Consultant in Public Health Medicine & Health Promotion
Primary Health Care-Qatar
Email: drmgalkuwari@hotmail.com

4. Dr. Mansoura Fawaz S. Ismail (Fawaz M, M.Sc., PhD family medicine)
Lecturer Family Medicine, Suez Canal University Egypt and Fulltime Trainer Family Medicine Department, HMC
Email: mansoura70@hotmail.com

Correspondence:
Dr. Mona T. Aseel,
Primary Health Care Department
P O Box 3050
Doha-Qatar

INTRODUCTION

Asymptomatic bacteriuria is a major risk factor for the development of urinary tract infections (UTI) in pregnancy , which are relatively common problems during pregnancy, due to the fact that physiological changes related to pregnancy make otherwise healthy women susceptible to serious infectious complications, arising from conditions such as asymptomatic and symptomatic urinary tract infections.¹

The combination of mechanical, hormonal and physiologic changes during pregnancy contributes to significant changes in the urinary tract, which has a profound impact on the acquisition, and natural history of bacteriuria during pregnancy. This includes dilatation of the ureter, decrease in ureteral peristalsis, and decrease in bladder tone. Additionally, the physiologic increase in plasma volume during pregnancy decreases urine concentration and increases urinary progestins and estrogens, which may lead to a decreased ability of the lower urinary tract to resist invading bacteria.^1,2

In addition to physiological changes, there are a number of conditions associated with an increased prevalence of asymptomatic bacteriuria in pregnancy. Low socio-economic status, sickle trait, diabetes mellitus and grand multi parity have been reported; each is associated with two-fold increase in the rate of Bacteriuria. It also increases with higher parity and advancing age.²

It is clear that asymptomatic bacteriuria is the major risk factor for developing symptomatic urinary tract infection and that symptomatic infection is associated with significant maternal and fetal risks.³ The significance of asymptomatic bacteriuria lies in its potential to cause cystitis or acute pyelonephritis, which develops in one third of the pregnant women with untreated bacteriuria.^4,5 In addition to symptomatic urinary tract infection, a variety of conditions has been reported to be associated with asymptomatic bacteriuria. Of these are pre-term labor, low birth weight, prematurely, pre-eclampsia and chronic renal disease that has been cited as significant adverse obstetric outcome and medical conditions. Thus, early detection and treatment can possibly decrease the occurrence of the side effects.^3,4

Therefore, proper screening and treatment of bacteriuria during pregnancy is necessary to prevent complications. The current recommendation is to obtain a urine culture between 12-16 weeks of gestation and pregnant women in whom asymptomatic bacteriuria is detected should be treated with antibiotics targeting the cultured organism, and they should undergo follow-up monitoring.^3,6-8

In the primary care setting, dipstick analysis and direct microscopic examination are often used for screening, but these tests have poor positive and negative predictive values to detect bacteriuria in asymptomatic persons. Although urine culture is expensive for routine screening in populations with a low prevalence of the urinary tract infection, it has been considered as the gold standard to detect asymptomatic bacteriuria. It is therefore the preferred screening test for pregnant women because no other currently available tests have sufficiently high sensitivity and negative predictive value in this population.^6,9

In Qatar there is insufficient local data on asymptomatic bacteriuria among pregnant women attending antenatal clinics in primary health care. Hence, this study aims to determine the prevalence and predictors of asymptomatic bacteriuria in pregnant women.

This cross-sectional study was conducted at four primary health care centers, which were randomly selected out of 23 centers distributed throughout Qatar. All pregnant women attending the antenatal clinic and who agreed to participate in this study between 1 August to 30 November 2008, were recruited. The study excluded any pregnant women who presented with any two of the following genitourinary complaints: dysuria, urinary hesitancy, urgency, slow stream, incontinence, frequency, incomplete voiding, and flank, suprapubic, or hypogastric pain. A structured questionnaire was administered by the attending physician or nurse to collect data related to demographic characteristics: (age, nationality, level of education); and medical history: (age of gestation, parity, hemoglobin level, previous history of UTI). Samples of 10-15ml urine were obtained and placed in a cold box. It was microscopically examined for pus cells, bacteria and ova, and then cultured within two hours. Urine samples that were not cultured within two hours were stored at 4°C. Samples were cultured on dried plates of Cysteine lactose electrolyte deficient agar (CLED), using a calibrated loop delivering 0.002 ml of urine. Plates were incubated aerobically at 37°C overnight. Colony counts yielding bacterial growth of 105/ml or more of pure isolates were deemed significant. Isolates were identified to species level using standard methods. The Statistical Package for Social Sciences, version 13.00 for windows (SPSS-13) was used for data entry with appropriate coding. Chi-square was used to evaluate the difference between proportion and categorical variables. Statistical level of significance was taken as 0.05 and 95% confidence interval (CI) was calculated. The binary logistic regression was used to assess strength of association between the dependent and independent variables under study. Odds ratio (OR) and CI were calculated in logistic regression analysis.

This study included 433 pregnant women attending antenatal care clinics at four primary health care centers. The mean age of the women included in the study is 26.4 years with a standard deviation of 5.2. Of the 433 pregnant women screened, 43 women had asymptomatic bacteriuria with prevalence of (9.9%). Escherichia coli, which comprised (31%), was the most frequent isolated organism, followed by Streptococcus agalactiae (30%) and Klebsiella pneumoniae (16%), as shown in Figure 1. The prevalence of asymptomatic bacteriuria was higher among women <30 years (10.7%) than those age >30 years (7.3%). Also women who were Qatari nationals have a higher prevalence (11.8%) compared with non-Qatari women (9.5%). Illiterate women and women with primary education have a higher prevalence rate (15.8% and 18.9% respectively) as shown in Table 1. In terms of characteristics related to the medical history, the prevalence of asymptomatic bacteriuria was higher among women with age of gestation of > 16 weeks (11%). Also, nullipara pregnant women had higher prevalence rate (11.4%). Table 2 shows that pregnant women who have a positive history of UTI had significantly higher prevalence than those who have no history of UTI (18% vs 7.8%, p-value <0.05). The prevalence of bacteriuria among anemic women with Hb level <10.5 mg/dl was higher than women who are not anemic (15.9% vs 8.9%, p-value <0.05). As illustrated in Table 3, the most significant predictors in the final best-fit model of logistic regression showed that pregnant women who have previous history of UTI are approximately 3 times more likely to develop asymptomatic bacteriuria as compared to those who have no history of UTI (OR=2.7, 95% CI=1.4-5.1). Being anemic during pregnancy increased the risk for developing asymptomatic bacteriuria compared to women with normal Hb level (OR= 1.5, 95% CI=1.1- 3.4).

* x² = 7.017 , degree of freedom (df)= 1, P-value <0.05
** x² = 2.910, df = 1, P-value <0.05

This study showed that the overall prevalence of asymptomatic bacteriuria among pregnant women attending primary health care centers in Qatar was 9.9%, which is higher than the reported prevalence in most of the previous studies. In theses studies the prevalence of asymptomatic bacteriuria in pregnancy varies from 4-7% (range 2-11%).⁴ For instance primary care based studies in Middle East countries reported that prevalence of asymptomatic bacteriuria is 6.1 % and 4.8% among pregnant women in Iran and United Arab Emirates respectively.^1,10 However the prevalence in this study is lower than what has been reported in Saudi Arabia.¹¹ In Asian studies the prevalence varies from one community to another. For example while the asymptomatic bacteriuria was 4.3% among Filipino pregnant women², this percent increases to 12% in rural areas in Bangladesh.¹² Similarly, in Africans studies the prevalence of asymptomatic bacteriuria is situated within the same range. For instance in Ethiopia and Ghana, the incidence of asymptomatic bacteriuria was 9.3% and 7.3% respectively.^13,14 The prevalence of asymptomatic bacteriuria varies between the studies even within the same country. For instance, asymptomatic bacteriuria in Nigerian studies ranges from 4% to 21%, depending on the population studied in different Nigerian provinces.¹⁵ Also, in western studies the same difference in estimated asymptomatic bacteriuria exists. For example while in the US the prevalence of asymptomatic bacteriuria is 2-7%⁶, the percentage jumps to 16% among Spanish pregnant women.¹⁶ This variation can be attributed to several factors such as the geographical variation, ethnicity of the subjects, setting of the study (primary care, community based, or hospitals), and the variation in the screening tests (urine dipstick, microscopy, culture).

Consistent with the majority of the reported studies, E. coli has been identified as the most common pathogen isolated among the pregnant women in this study. However E. coli formed 31% of isolated organism which is lower than what have been reported in different countries like Ethiopia (79%)¹⁴, Turkey (77%)¹⁷, Philippines (50%)2 and Ghana (37%)¹². The predominance of E. coli could be attributed to the urinary stasis, which is common in pregnancy and since most E. coli strains prefer that environment, to cause UTI5.

Literature revealed that there are various factors that are associated with asymptomatic bacteriuria during pregnancy. For example some previous research found that the incidence of asymptomatic bacteriuria is highly associated with multiparity and during the third trimester.^15,17,18 Furthermore demographic determinants such as illiteracy or being from a low socioeconomic background is also associated with asymptomatic bacteriuria during pregnancy.¹⁸ In our study, such association has not been identified between these characteristics and bacteriuria.

This study found a strong association between previous history of UTI and low hemoglobin level with occurrence of asymptomatic bacteriuria during pregnancy. Positive history of UTI and anemia were identified as predictors for developing asymptomatic bacteriuria during pregnancy. Our results showed that the history of UTI is considered as the strongest predictor which is reported by some other studies.^2,7,10

In agreement with previous studies that found the risk of bacteriuria is doubled in women with anemia (OR=2.5) or sickle cell trait (OR=2), 10,19 the current study found a similar risk but less than that reported (OR=1.5). Determining such predictors can help health care professionals to identify those women who are more likely to get bacteriuria, however this study did not investigate other risk factors for bacteriuria such as diabetes mellitus and urinary tract anomalies.^7,10,19

In conclusion, the prevalence of asymptomatic bacteriuria in pregnant women attending primary health care centers in Qatar is 9.9%, and the predominant organism is E.coli. Current screening for asymptomatic bacteriuria in pregnant women attending antenatal clinics at primary care level should focus on their first pre-natal visit especially if they are anemic, and those with a history of urinary tract infection.

Acknowledgments: We wish to acknowledge the nurse and lab staff for their collaboration with the researcher's.

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