literature review of uti in pregnancy

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How to Treat a UTI at Home

Urinary tract infections cause discomfort in millions of people. They are usually treated with an antibiotic, but are treatable from home if symptoms are mild. If you are experiencing uncomfortable UTI symptoms like burning during urination, the strong urge to go or frequent urination, use this home remedy for UTI.

Increase Probiotics

The best way to treat and avoid a UTI at home is to increase your intake of probiotics. Probiotics aid in healthy digestion and gut flora. You can take a supplement or eat foods high in powerful probiotics. Try eating a fermented food like kimchi or a yogurt with added probiotics. Drinks like kombucha are also a good additive. If you do choose to take an antibiotic, probiotics can decrease negative side effects and keep your good bacteria balanced.

Take Cranberry Supplements

Cranberry is a common all-natural way to heal a urinary tract infection. You can drink cranberry juice that’s low in sugar or take a cranberry supplement for UTIs. Cranberry flushes bad bacteria from the urinary tract. Make sure you drink plenty of water while taking cranberry to increase urination and flush out your system.

Change Your Habits

Sometimes bad habits increase the chance of a urinary tract infection forming or getting worse. Make sure to increase your water intake and cut down on sugary beverages and caffeine. Always wipe from front to back and use fragrance-free hygiene products to decrease the risk of infection. Increase your fiber intake to balance digestive health. Decrease your use of alcohol and nicotine to keep your body healthy. Changing your habits can significantly decrease your chance of forming a UTI.

Increase Vitamin C

Vitamin C increases the acidity of your urine, which kills of UTI-causing bacteria, according to Healthline. Try taking around 100 milligrams of vitamin C daily to flush out any bad bacteria. You can take a supplement or increase your intake of certain fruits and vegetables. Try a grapefruit or orange during a breakfast or as a snack during lunch. Drink a glass of orange juice in the morning before work.

Don’t Hold It

Studies show that holding your urine for long periods of time can increase the risk of a UTI. When you have to go, don’t wait. You’ll risk a buildup of bacteria if you do. Always go directly after intercourse to avoid bacteria spreading, as well. Urinating just a small amount can help, too. No matter the urgency, it’s good to empty your bladder so your body can naturally flush out any bacteria it may be holding.

Urinary Tract Infection in Pregnancy and Its Effects on Maternal and Perinatal Outcome: A Retrospective Study

Lekshmi balachandran.

1 Obstetrics and Gynecology, Corniche Hospital, Abu Dhabi, ARE

Leena Jacob

Reem al awadhi, lamia o yahya.

2 Pharmacology and Therapeutics, Corniche Hospital, Abu Dhabi, ARE

Khlood M Catroon

Lakshmi p soundararajan, saleema wani, sara alabadla, yassmin a hussein.

A urinary tract infection (UTI) is a common medical condition complicating pregnancy with adverse maternal and perinatal outcomes. This study aimed to assess any adverse maternal and perinatal morbidity related to UTI in pregnancy, focusing on identifying common uropathogens and their antibiotic sensitivity and resistance patterns.

We conducted a retrospective cohort study at Corniche Hospital, Abu Dhabi. The study population consisted of 549 women in the exposed group (i.e., those with at least one episode of UTI in pregnancy in 2018) and 329 in the comparison group (i.e., those without UTI). Statistical analysis was done using SPSS Statistics for Windows, Version 19.0 (SPSS Inc., Chicago, IL). The study's primary outcome measures were preterm birth, recurrent UTI, pyelonephritis, and low birth weight (LBW).

Women who had a UTI during pregnancy had more preterm deliveries than those without a UTI (c2=7.092; p=0.007). Recurrent UTI was observed in 26.6% of women with UTI, while the incidence of pyelonephritis was relatively low in this group (1.45%). There was no significant association between LBW and UTI in pregnancy (c 2 =0.097; p=0.756). The most common bacteria isolated from women with UTI were Group B Streptococcus (GBS, 31.3%), followed by Escherichia coli (30.9%). They were sensitive to a wide range of antibiotics.

According to our results, significant predictors of bacteriuria in pregnancy history include UTI, renal calculi, and nulliparity. Women with UTI in pregnancy are more likely to have preterm delivery. However, adequate management can minimize other complications like pyelonephritis and adverse perinatal outcomes. Available evidence prompts the recommendation of routine screening for asymptomatic bacteriuria (ASB) in early pregnancy to minimize complications and identify those women at significant risk for preterm delivery.

Introduction

Urinary tract infections (UTI) continue to be one of the most common medical conditions complicating pregnancy, with a prevalence of approximately 20% [ 1 ]. A UTI is diagnosed when there is an overgrowth of bacteria in the urinary tract (≥105 counts/mL of urine), irrespective of the presence of clinical symptoms [ 2 ]. UTI include a spectrum of disorders, ranging from those affecting the lower urinary tract, like asymptomatic bacteriuria (ASB) and cystitis, to those affecting the kidney, such as pyelonephritis. The prevalence of ASB is 2% to 10% of cases [ 3 ]. Clinical trials in the 1960s and 1970s reported that untreated ASB had a 20% to 30% risk of progressing into pyelonephritis. Early diagnosis and adequate treatment with antibiotics helped reduce the risk by 80% [ 4 ].

Organisms causing UTI in women (whether pregnant or not) are of the same species and virulence factors. Bacteria commonly isolated include Escherichia coli , Klebsiella pneumonia , Proteus, Acinetobacter, Staphylococcus saprophyticus , Group B Streptococcus (GBS), and Pseudomonas aeruginosa [ 5 - 7 ].

Advanced maternal age, multiparity, sexual intercourse, diabetes, sickle cell anemia, previous history of UTI, immunodeficiency, and urinary tract abnormalities are risk factors for UTI in pregnancy [ 6 , 7 ]. UTI in pregnancy is considered a risk factor for adverse maternal and perinatal outcomes. Schieve et al. reported an increased association of UTI with premature labor, hypertensive disorders of pregnancy, anemia, and amnionitis [ 8 ]. Delzell and Lefevre noted similar outcomes but added low birth weight (LBW) infants as an additional outcome [ 9 ]. However, the population-based nationwide study by Chen et al. in Taiwan found no increased risk for LBW, no incidence of neonates small for gestational age, or preterm babies in women with antenatal UTI [ 10 ]. Given the conflicting reports in the literature, we conducted this study to look for any adverse maternal and perinatal morbidity related to UTI in pregnancy and identify common uropathogens and their antibiotic sensitivity and resistance patterns.

Materials and methods

We conducted a retrospective cohort study of pregnant women who received antenatal care between January 1, 2018, and December 31, 2018, at Corniche Hospital, a tertiary-care maternity hospital in Abu Dhabi, United Arab Emirates. The Corniche hospital ethics committee granted ethical approval (Reference No: {"type":"entrez-nucleotide","attrs":{"text":"CH050993","term_id":"45154858","term_text":"CH050993"}} CH050993 ) even though the study did not directly involve human subjects.

The study group consisted of pregnant women who had at least one positive urine culture during the study period. All nonpregnant patients with UTI (including postpartum UTI), those with miscarriages, and those with preexisting congenital renal tract anomalies and chronic renal diseases were excluded.

The comparison group consisted of pregnant women who attended Corniche hospital for antenatal care during the same period but had no episodes of UTI in pregnancy. Five hundred women booked in the initial few months were selected from the booking data after excluding those with confirmed UTI during pregnancy. The exclusion criteria for the study group were further applied to the final comparison group (n=330).

After applying the exclusion criteria, we collected data from a total of 993 pregnant women, including women with confirmed UTI (n=663) and those without UTI (n=330). In the UTI group, 114 women were excluded from the analysis due to lack of follow-up data or postnatal diagnoses, leaving 549 cases in the exposed group. In the comparison group, one case was excluded for the same reason, leaving 329 women in the control cohort without UTI. A total of 878 women were involved in the final analysis.

Thirty-one women with UTI were diagnosed at advanced gestation of 37 weeks or later in their pregnancy. Therefore, they were excluded from determining the association between UTI and preterm delivery. There were no such exclusions in the comparison group.

We recorded basic demographic data consisting of age, nationality, body mass index (BMI), and parity and the previous history of UTI, comorbidities, gestational age at first diagnosis, and delivery and birth weight of babies. Urine culture results with bacterial isolates, their sensitivity, antibiotics used, and recurrence-related data were obtained from the patients' electronic medical records. In addition to routine screening at booking, cultures were also done when patients presented with symptoms of UTI.

The primary outcome was maternal and perinatal morbidity associated with UTI in pregnancy. Maternal outcomes included those who had premature delivery (i.e., those with the onset of labor and delivery prior to 37 completed weeks of gestation), those with recurrent UTI (i.e., those with more than one episode of UTI in the index pregnancy), and pyelonephritis with clinical features of upper UTI and diagnosed as pyelonephritis in the patients' records. Perinatal morbidity was measured in terms of LBW (<2500 g at ≥37 weeks), prematurity (<37 weeks' gestation), and preterm LBW (birthweight <10th percentile on Fenton's birthweight distribution chart at each gestational age) [ 11 ].

The secondary outcome measures included the identification of the common organisms responsible for primary and recurrent infections. We also assessed the type of recurrent infections (whether due to relapse or reinfection) and the antibiotic sensitivity and resistance patterns.

Recurrent UTIs are symptomatic UTIs that occur after the resolution of an earlier episode, usually after appropriate treatment [ 12 ]. Recurrent UTIs include relapses (i.e., symptomatic recurrent UTIs with the same organism following adequate therapy) and reinfection (i.e., recurrent UTIs with previously isolated bacteria after treatment and with a negative intervening urine culture, or a recurrent UTI caused by a second bacterial isolate) [ 13 ].

Data analysis

We used SPSS Statistics for Windows, Version 19.0 (SPSS Inc., Chicago, IL) to find the association of variables, and statistical tests (i.e., T-test, comparison of means, tests of association, Chi-square, and the test of proportions) were carried out appropriately. Continuous and categorical data were analyzed using descriptive statistics and presented as mean, standard deviation, and percentage. Associations with p<0.05 were considered statistically significant.

In 2018, 4277 pregnant women visited Corniche hospital for antenatal care, with 663 having culture-proven UTI (15% prevalence). Figure Figure1 1 depicts the demographic characteristics of the study participants. Most of the women who participated in our study were aged 31 to 40 (49.5%) or 21 to 30 (44%). The mean age of the exposed group was 30.5 years, while that of the comparison group was 31.8 years. There was no significant association noted between age and the risk of UTI (c2=5.971; p=0.113).

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BMI: body mass index

The mean BMI of women with UTI was 28.5 kg/m 2 , and the control group's mean BMI was 28.4 kg/m 2 . There was no significant association between BMI and UTI (c2=1.29; p=0.25). However, we noted a significant association between parity and UTI. Urinary infection was more common in nulliparous women than in multiparous women (c2 = 6.337; p =0.042). UTI was more prevalent among UAE nationals as opposed to other nationalities (c2=10.99; p=0.0009). A history of UTI was associated with more cases of UTI in pregnancy than those without a pre-pregnancy UTI (c2=63.881; p=0.0001).

The commonly associated comorbidities like anemia, diabetes, and hypertension did not significantly correlate with UTI (Table (Table1). 1 ). However, those with hypothyroidism were more likely to have UTIs in pregnancy (c2=13.68; p=0.0002). All the women with renal calculi (n=18) developed UTI in pregnancy.

*Statistically significant.

UTI, urinary tract infection; Hx, history; GDM, gestational diabetes mellitus; PET, preeclampsia; MP, multiple pregnancies; HT, hypertension.

One hundred fifteen women (21%) with UTI presented with one or more UTI symptoms. However, most women with UTI (79%) were asymptomatic and identified by routine screening at their visit.

Maternal and perinatal outcomes of UTI in pregnancy

Study participants with UTI had more preterm deliveries compared to those without UTI (c2=7.092; p=0.007; odds ratio [OR], 1.659; 95% confidence interval [CI], 1.142 to 2.408). This was not significantly associated with their parity, age group, BMI, or nationality. Of the associated comorbidities, only hypertension in pregnancy was linked to preterm deliveries. Similarly, gestational age at first diagnosis of UTI was also not associated with gestational age at delivery (c2=0.5432; p=0.76; Table Table2 2 ).

In the exposed group, 146 women (26.6%) had recurrent UTI. Relapse of infection was noted in 71 (48%) of these women, and reinfection in 107 women (73%). Thirty-two women (22%) had both relapse and reinfection. None of the demographic factors or associated comorbidities were associated with recurrent UTI except for those with a previous history of UTI; they were 1.9 times more likely to have a recurrence (c2=8.8974; p=0.002; OR, 1.88; 95% CI, 1.23-2.87). The likelihood of preterm delivery in those with recurrent UTI was not significantly different from that of women with one episode of UTI in pregnancy (c2=0.111; p=0.739). There were eight cases of pyelonephritis (1.45%) in the study group, of which two were preterm deliveries. Because the numbers were low, it was impossible to analyze the data for a significant association.

A small percentage (5.3%) of babies born to mothers with UTI had LBW, while a similar percentage (5.8%) of babies from mothers with no UTI had LBW. Essentially, there was no significant relationship between LBW and the presence or absence of UTI in pregnancy (c2=0.097; p=0.756). Premature babies were more common in women with UTI than in the comparison group (c2=7.092; p=0.007; Table Table3 3 ).

UTI, urinary tract infection; LBW, low birth weight; NA, not applicable.

The most common bacteria isolated from women with UTI were GBS (31.3%), E. coli (30.9%), Enterococcus (15.8%), K. pneumoniae (13.1%), and other minor groups of organisms (9%; Figure Figure2). 2 ). ASB constituted 79% of the confirmed UTI cases. The bacterial isolates in ASB followed the same pattern, with GBS in 32%, E. coli in 28%, and Enterococcus and Klebsiella in 15% and 14% of cases, respectively.

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Object name is cureus-0014-00000021500-i02.jpg

GBS, Group B Streptococcus; UTI, urinary tract infection.

The most common organism responsible for recurrent UTI was E. coli (40%), with GBS, Enterococcus, and K. pneumoniae sharing a majority of the remaining 60%. E. coli was also the primary organism causing UTI relapse (n=24; 34%). GBS was 100% sensitive to vancomycin and 99% sensitive to ampicillin, while 42% were resistant to clindamycin. E. coli was only 93% sensitive to nitrofurantoin. A portion (24%) of E. coli isolates were extended-spectrum beta-lactamase (ESBL)-producing. Of those, 88% were sensitive to nitrofurantoin. The sensitivity of E. coli to fosfomycin was 96%, with 92% sensitivity for ESBL-producing isolates. Enterococcus faecalis isolates were 100% sensitive to ampicillin, nitrofurantoin, and teicoplanin, with no relevant resistance patterns. K. pneumonia isolates were 94% sensitive to ceftazidime, cefotaxime, and co-amoxiclav.

The prevalence of UTI among pregnant women attending Corniche hospital was 15%, with the majority (11.8%) remaining asymptomatic and only 3.2% presenting with one or more symptoms of UTI. This was in contrast to previous studies by Faidah et al. in Saudi Arabia (who reported a 20% prevalence of UTI, of which 12% were symptomatic and 8% were asymptomatic) and Lee et al. (who reported a UTI prevalence of 8.9%, with 4.4% symptomatic UTI and 4.5% with ASB) [ 14 , 15 ]. The increased prevalence of ASB in our population could be attributed to the strict adherence to our hospital policy of getting a urine culture done at booking for every pregnant woman.

The association of demographic factors and UTI has been controversial, with some studies showing increased risk with advanced maternal age and multiparity [ 16 ]. However, Hamdan et al. found no significant association [ 17 ]. Our study showed nulliparous women to be more likely to develop UTI. Age, BMI, nationality, and gestational age were not associated with UTI development.

In our study, a history of UTI was significantly associated with an increased risk of UTI. Similar findings were noted by Pastore et al., who identified the two strongest predictors of bacteriuria in prenatal care as antepartum UTI prior to prenatal care and a pre-pregnancy history of UTI [ 18 ].

Hypothyroidism had a significant association with UTI in pregnancy in our study but has not been reported as such, according to a literature search. Only one case was reported by Correia et al. of an association between subclinical hypothyroidism and recurrent UTI in a nonpregnant woman [ 19 ]. In the absence of additional evidence, further studies are needed to ascertain the significance.

Another significant outcome of this study was the association between preterm delivery and UTI. Similar outcomes were reported by Shieve et al. and Siakwa et al. [ 8 , 20 ]. In 1989, a meta-analysis published by Romero et al. concluded that non-bacteriuric patients had only approximately two-thirds the risk of LBW and half the risk of preterm delivery compared to those with untreated symptomatic bacteriuria, and antibiotic treatment reduced the risk of LBW [ 21 ]. Our study differed from this meta-analysis because, despite the fact that 89% of women with UTI received appropriate antibiotic treatment, the risk of preterm delivery remained high. However, this did not translate into a significant increase in LBW babies. Findings similar to our study were reported by Smaill et al., who noted that antibiotic treatment for ASB reduced the risk of pyelonephritis (relative risk [RR], 0.23; 95% CI, 0.13 to 0.41) and LBW (RR, 0.66; 95% CI, 0.49 to 0.89), although no significant reduction in the rates of preterm birth was demonstrated [ 22 ].

Several studies have shown E. coli and other Gram-negative isolates (namely the Klebsiella species, Acinetobacter baumannii , and Proteus mirabilis ) to be responsible for 70% to 80% of UTI in pregnancy. Gram-positive organisms (e.g., Enterococcus faecalis and GBS) were isolated in approximately 10% of UTIs in pregnant women [ 23 , 24 ]. However, our study revealed a very high prevalence of GBS bacteriuria (about 30%) in symptomatic and asymptomatic UTIs, followed closely by E. coli . Geographic variation with resultant differences in cultural and behavioral practices could account for the deviation. The identification of E. coli as the most common bacteria responsible for recurrent UTI, particularly relapse, could be explained by the increased susceptibility to vaginal colonization by the adjacent rectal flora and the inherent affinity for uropathogenic coliforms to adhere to uroepithelial cells [ 12 ].

Of the different antibiotics studied, ampicillin was very effective against GBS and Enterococcus species. Fosfomycin has evolved as an effective first-line treatment for E. coli strains, including ESBL-positive ones. Similar findings were reported by Rosana et al. [ 25 ]. Nitrofurantoin is comparatively less effective against E. coli ; however, it is 100% effective against Enterococcus species. The very high resistance to clindamycin in GBS UTI limits its viability as an alternative in penicillin-allergic patients. As recommended by the 2010 Centers for Disease Control and Prevention guidelines [ 26 ], vancomycin with 100% sensitivity becomes the preferred alternative in this situation.

Limitations

Our study was limited by its retrospective nature, resulting in information bias due to missing data and selection bias due to loss of follow-up. Despite this limitation, our study featured patients of similar demographics in both the UTI and comparison groups.

Conclusions

Based on our study results, a history of UTI, renal calculi, and nulliparity are significant predictors of bacteriuria in pregnancy, a large portion of which is asymptomatic. Women with UTI in pregnancy are more likely to have preterm delivery. However, adequate management can minimize other complications like pyelonephritis and adverse perinatal outcomes. Our study emphasizes the importance of routine screening for ASB in pregnancy rather than screening only those women with symptoms. This approach would help identify high-risk women at significant risk for preterm delivery, allowing targeted care and proper use of available resources. On the other hand, widespread injudicious use of antibiotics and the subsequent development of antibiotic resistance are growing concerns. Therefore, health care teams should consider regular reviews of antibiograms and choose the appropriate antibiotic in each case.

Acknowledgments

We would like to thank Mr. Ramdas Changarath (statistician) and Mr. Manish Singh (Biostatistician) for helping with study designing, data analysis, and reporting.

The content published in Cureus is the result of clinical experience and/or research by independent individuals or organizations. Cureus is not responsible for the scientific accuracy or reliability of data or conclusions published herein. All content published within Cureus is intended only for educational, research and reference purposes. Additionally, articles published within Cureus should not be deemed a suitable substitute for the advice of a qualified health care professional. Do not disregard or avoid professional medical advice due to content published within Cureus.

The authors have declared that no competing interests exist.

Human Ethics

Consent was obtained or waived by all participants in this study. Corniche Hospital Ethics Committee issued approval {"type":"entrez-nucleotide","attrs":{"text":"CH050993","term_id":"45154858","term_text":"CH050993"}} CH050993 . Ethics committee approval was obtained even though study was retrospective and did not directly involve human subjects.

Animal Ethics

Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue.

Research article
Open access
Published: 30 May 2019

The etiology and prevalence of urinary tract infection and asymptomatic bacteriuria in pregnant women in Iran: a systematic review and Meta-analysis

Milad Azami 1 , 2 ,
Zahra Jaafari 3 ,
Mansour Masoumi 4 ,
Masoumeh Shohani 5 ,
Gholamreza Badfar 6 ,
Leily Mahmudi 7 &
Shamsi Abbasalizadeh 2

BMC Urology volume 19 , Article number: 43 ( 2019 ) Cite this article

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Urinary tract infection (UTI) is a common clinical problem in pregnant women. Bacteriuria in pregnancy without antibiotic treatment could result in complications. This study aims to investigate the etiology and prevalence of UTI and asymptomatic bacteriuria (ASB) in pregnant women in Iran.

This meta-analysis follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. To avoid bias, all steps of the study were carried out independently by two researchers. We conducted a comprehensive search on all the related literature in national databases, including IranDoc, SID, Barakat Knowledge Network System, RICST, Magiran, Iranian National Library and international databases, including Scopus, Embase, Science Direct, PubMed/ Medline, Cochrane Library, Web of Sciences, EBSCO, as well as Google Scholar search engine until June 2018. After considering the inclusion/exclusion criteria and qualitative evaluation, studies were analyzed based on random effects model using Comprehensive Meta-Analysis Software Version 2.

In 31 studies with a sample size of 20,309, the prevalence of ASB in pregnant Iranian women was estimated to be 8.7% (95%CI: 7.2–10.4). The lowest and highest prevalence of ASB were observed in the third trimester (6.1% [95%CI: 2.1–16.4]) and first trimester (11.7% [95%CI: 7.9–16.9]), respectively. Subgroup analysis of the prevalence of ASB based on geographical region ( P = 0.002) and province ( P < 0.001) was significant but for the quality of studies ( P = 0.51) was not significant. In 17 studies including 48,731 pregnant women, the prevalence of UTI was estimated to be 9.8% (95%CI: 7.6–12.5). The test for subgroup differences of prevalence of UTI for province ( P < 0.001) was significant but for geographical region ( P = 061) and quality of studies ( P = 0.11) was not significant. Meta-regression model for the prevalence of UTI and ASB in pregnant women in Iran based on year of the studies was significant ( P < 0.001). The most common microorganism involved in the etiology of UTI (61.6% [95%CI: 51.6–70.7]) and ASB (63.22% [95%CI: 51.2–73.8]) was E. coli .

UTI and ASB are prevalent in pregnant women in Iran. Therefore, UTI screening is essential in pregnant women. The most common microorganism involved in the etiology of UTI and ASB in pregnant women in Iran is E.coli .

Peer Review reports

Urinary tract infection (UTI) is a common clinical problem that constitutes about 1–6% of medical referrals and includes urinary tract, bladder and kidney infections [ 1 ]. UTI may be symptomatic or asymptomatic, while asymptomatic bacteriuria (ASB) is of particular importance due to lack of any symptom [ 2 , 3 ]. UTI and its related complications cause about 150 million deaths per year around the world [ 4 ].

In pregnant women, physiological and anatomical changes in the urinary tract, as well as immune system changes during pregnancy increase the prevalence of ASB and in some cases lead to the symptomatic infection, resulting in serious risks for both mother and fetus. Increasing age, parity, diabetes, sickle cell anemia, history of UTI, urinary tract disorders and immune deficiency may increase the risk of UTI in pregnant women [ 5 , 6 , 7 ].

Bacteriuria in pregnancy without antibiotic treatment could result in complications such as preterm labor, pre-eclampsia, hypertension, pyelonephritis, anemia, amnionitis, low birth weight, neonatal deaths (stillbirths), bacteremia and toxic septicemia [ 8 , 9 , 10 ]. Treatment of bacteriuria in pregnancy reduces the risk of complications. Therefore, screening for early diagnosis and treatment of bacteriuria in women during pregnancy is necessary to prevent its complications [ 11 ].

The overall prevalence of bacteriuria in pregnant Iranian women was reported to be 2–41% [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Therefore, there is inconsistency in the results of studies. Thus, determining the prevalence of ABS, UTI and the most common pathogenic microorganisms involved in its creation is a valuable diagnostic capability in different countries.

Because of the inconsistency in different reports, reviewing various studies cannot be sufficient to achieve this goal. In systematic reviews, examining all related documents and combining them through meta-analysis provides a more complete picture of the dimensions of a problem [ 55 – 57 ].

This study aims to assess the prevalence of UTI, ASB and pathogens involved in bacteriuria among pregnant women in Iran.

Study protocol

This systematic review and meta-analysis follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [ 57 ]. To avoid bias, all steps of study were carried out independently by two researchers and in case of controversies, the problem was resolved by a third researcher.

Inclusion and exclusion criteria

Inclusion criteria according to PICO (Evidence-Based Medicine) [ 58 ] were as follows [ 1 ]: P opulation: The epidemiologic studies that investigated UTI, ASB and etiology among pregnant women [ 2 ]; I ntervention: Urine culture for confirmed UTI and ASB [ 3 ]; C omparison: That can show the prevalence of UTI and ASB based on geographical region, province and trimester of pregnancy [ 4 ]; O utcome: Studies that estimated the UTI, ASB and etiology prevalence in pregnant women.

The exclusion criteria were: 1. Non-random sampling; 2. Non-pregnant Iranian women; 3. Irrelevance with the subject of the research; 4. Incomplete information such as failing to report the prevalence; 5. Qualitative studies; 6. Review articles, case reports and editorials; 7. Duplicates.

Search strategy and study selection

We conducted a comprehensive search on all English and Persian related literature in national databases, including Iranian Research Institute for Information Science and Technology (IranDoc) ( https://irandoc.ac.ir ), Scientific Information Database (SID) ( http://www.sid.ir/ ), Barakat Knowledge Network System ( http://health.barakatkns.com ), Regional Information Center for Science and Technology (RICST) ( http://en.ricest.ac.ir/ ), Magiran ( http://www.magiran.com/ ), Iranian National Library ( http://www.nlai.ir/ ) and international databases, including Scopus, PubMed/ Medline, Science Direct, Cochrane Library, Embase, Web of Sciences, EBSCO, as well as Google Scholar search engine until June 2018. We searched the articles using English MeSH keywords and Persian equivalents: “Pregnant”, “Gestational”, “Pregnancy”, “Prenatal Care”, “Urinary Tract Infection”, “Bacteriuria”, “Iran” and all possible combinations of keywords using “AND” and “OR” operators for English databases. In addition, the manual search was conducted to find more studies by screening the reference list of all articles included in the meta-analysis. PubMed combination search was as follows: (“Pregnant”[Title/Abstract] OR “Pregnancy”[Title/Abstract]) OR “Gestational”[Title/Abstract] OR “Prenatal Care”[Title/Abstract] AND (“Urinary Tract Infection”[Title/Abstract] OR “Bacteriuria”[Title/Abstract] AND “Iran”[Title/Abstract/Affiliation].

It is worth noting that ‘High Sensitive Searching’ was used in databases; in addition, the search was conducted by qualified researchers and experts in the field of database searching (“M. Azami” and “Z. Jaafari”).

Quality assessment

Authors assessed the quality of studies according to the modified Newcastle Ottawa Scale (NOS) for cross-sectional studies [ 59 ], which includes eight sections, and evaluated the selected articles from the selection, comparability, exposure assessment, and outcome. Points of 0–5, 6–7 and 8–10 were considered as low quality, moderate quality and high quality, respectively. A minimum score of 6 was considered as a criterion to include an article.

Data extraction

The checklist was designed based on goals. This checklist included: authors, place, province, region, year of publication, year of study, study design, mean age, sample size, prevalence of UTI, ASB and microorganisms involved in bacteriuria. Sample size and prevalence of UTI and ASB for the first, second and third trimester of pregnancy were independently extracted by two researchers.

Statistical analysis

Binomial distribution formula was used to estimate the standard error for the prevalence of UTI, ASB and pathogens involved in bacteriuria. The heterogeneity of the studies was assessed using Cochran’s Q test and I 2 index, and interpreted as follows: 0–24% may not be important, 25–49% indicates moderate heterogeneity, 50–75% indicates substantial heterogeneity and over 75% indicates considerable heterogeneity [ 60 ]. To combine data in high heterogeneity, we used the random effects model. To explore the potential sources of heterogeneity, subgroup analysis was preformed based on geographical region, province and trimester of pregnancy [ 61 , 62 ]. We used the meta-regression model for the prevalence of UTI and ASB according to year of the study. Publication bias was measured by reviewing the funnel plots and through Begg and Egger’s tests. Meta-analysis of data was performed using Comprehensive Meta-Analysis Software Version 2 and the significance level was considered less than 0.05.

Search results

In the systematic review, 520 potentially relevant articles were identified, and after screening the titles and abstracts, 260 studies were excluded because of being duplicate, and the full text of 260 possibly related articles was studied. After the evaluation of exclusion/inclusion criteria and the quality of articles, 42 eligible studies, published from 1995 to 2015, were included in meta-analysis (Fig. 1 ).

A flow diagram following the PRISMA template

Study characteristics

42 eligible articles (17 studies for UTI and 31 studies for ASB) including 67,776 pregnant women were investigated. Mean and standard deviation (SD) for age was 26.47 ± 5.47 years. Other study characteristics are shown in Table 1 .

Total prevalence of ASB and sensitivity analysis

The heterogeneity rate for the prevalence of ASB was high (I 2 = 93.38, P < 0.001). In 31 studies with a sample size of 20,309, the prevalence of ASB in pregnant Iranian women was estimated to be 8.7% (95% CI:7.2–10.4) (Fig. 2 ). The lowest and highest prevalence of ASB were 2 and 29.1% in the studies of Farajzadegan [ 13 ] and Rahimkhani [ 43 ], respectively (Fig. 2 ). Sensitivity analysis for the prevalence of ASB in Fig. 3 shows that after removing a study at a time, the result is still robust.

Prevalence of asymptomatic bacteriuria in pregnant women in Iran

Sensitivity analysis for the prevalence of asymptomatic bacteriuria in pregnant women in Iran

Subgroup analysis of the prevalence of ASB based on geographical region and province

The lowest prevalence of ASB in pregnant women was estimated to be in the South of Iran (5.1% [95% CI: 3.3–7.8]) and Golestan province (3.7% [95% CI: 2.6–5.2]). The highest prevalence of ASB in pregnant women was estimated to be in the East of Iran (13.9% [95% CI: 10.3–18.6]) and Kerman province (24.1% [95% CI: 19.7–29.1]). The test for subgroup differences for geographical region ( P = 0.002) and province ( P < 0.001) was significant (Table 2 ).

Subgroup analysis of the prevalence of ASB based on quality of studies

The prevalence of ASB among pregnant women in terms of quality of studies based on NOS checklist was estimated to be 9.3% [95% CI: 7.1–12.1]) and 8.3% [95% CI: 6.4–10.6]) in moderate-quality and high-quality studies, respectively. No significant difference was found ( P = 0.51) (Table 2 ).

The prevalence of ASB based on trimester of pregnancy

The lowest and highest prevalence of ASB were estimated in the third trimester (6.1% [95% CI: 2.1–16.4]) and first trimester (11.7% [95% CI: 7.9–16.9]), respectively (Fig. 4 ).

Prevalence of asymptomatic bacteriuria in the first ( a ), second ( b ) and third ( c ) trimesters in Iran

Prevalence of UTI in pregnant women

The heterogeneity rate for the prevalence of UTI was high (I 2 = 98.12%, P < 0.001). In 17 studies including 48,731 pregnant Iranian women, the prevalence of UTI was estimated to be 9.8% (95% CI: 7.6–12.5). The lowest prevalence was in the study of Shahhosseini (2.8%) and the highest prevalence was in the study of Sharemi (23.6%) (Fig. 5 ). Sensitivity analysis by removing a study at a time showed that the result for the prevalence of UTI was robust (Fig. 6 ).

Prevalence of urinary tract infection in pregnant women in Iran

Sensitivity analysis for the prevalence of urinary tract infection in pregnant women in Iran

Subgroup analysis of the prevalence of UTI based on geographical region and province

The prevalence of UTI among pregnant women in the South of Iran (7.2% [95% CI: 3.9–13.1]) and Khuzestan province (5% [95% CI: 4.7–5.3]) were the lowest and in the North of Iran (11.4% [95% CI: 8.2–15.6]) and Alborz province (21.6% [95% CI: 18.2–25.6]) were the highest. The test for subgroup differences for geographical region ( P = 061) was not significant but for province ( P < 0.001) was significant (Table 2 ).

Subgroup analysis of the prevalence of UTI based on quality of studies

The prevalence of UTI among pregnant women in terms of quality of studies based on NOS checklist was estimated to be 12.5% [95% CI: 8.7–17.6]) and 8.6% [95% CI: 6.4–11.5]) in moderate-quality and high-quality studies, respectively. No significant difference was found ( P = 0.11) (Table 2 ).

Total prevalence of UTI and ASB with omission of high prevalence reports

Four studies (Rahmani [ 35 ], Norouzzadeh [36], Jalali [ 40 ] and Sharemi [ 51 ]) for prevalence of UTI and three studies (Namazi [ 24 ], Aaron [ 20 ] and Rahimkhani [ 43 ]) for prevalence of ASB reported high prevalence. After omitting these studies, the prevalence of UTI and ASB was estimated to be 7.6% (95% CI: 6.0-9.7) and 7.8% (95% CI: 6.7–9.0), respectively (Fig. 7 ).

Prevalence of urinary tract infection ( a ) and asymptomatic bacteriuria ( b ) in pregnant women in Iran with deleted high prevalence reports (4 studies for prevalence of UTI: Rahmani, Norouzzadeh, Jalali and Sharemi and 3 studies for ASB: Namazi, Rahimkhani and Aaron)

Meta-regression

Meta-regression model for the prevalence of UTI and ASB in pregnant women in Iran based on year of the studies was significant ( P < 0.001 for UTI and P < 0.001 for ASB) (Fig. 8 ).

Meta-regression model for the prevalence of urinary tract infection ( a ) and asymptomatic bacteriuria ( b ) in pregnant women in Iran based on year of the studies

The prevalence of microorganisms

The most common microorganism involved in the etiology of UTI (61.6% [95% CI: 51.6–70.7]) and ASB (63.22% [95% CI: 51.2–73.8]) was E. coli . The lowest prevalence was Proteus with 2.6% (95% CI: 1.9–3.4) for UTI and 3.6% (95%CI: 2.0–6.3) for ASB (Table 3 ).

The results of this meta-analysis indicated that the prevalence of ASB and UTI in pregnant Iranian women was 8.7 and 9.8%, respectively. In subgroup analysis, geographic region, province and year of the studies can be a cause of heterogeneity between studies. The most common microorganism involved in the etiology of ASB and UTI in pregnant women in Iran was E. coli (63.2 and 61.6%, respectively), while meta-regression model based on year of the studies for E. coli (for ASB) had a significantly decreasing trend. The healthcare structure for pregnant women is a state funded program running in Iran. This program included urine testing (urine culture test and urine analysis) in the first prenatal visit [ 12 , 13 , 14 , 15 ].

Prevalence of bacteriuria in pregnancy is affected by several factors such as multiple pregnancies, age, previous history of UTI, diabetes, urinary tract anatomic abnormalities, lack of personal hygiene and socioeconomic status [ 63 , 64 ]. In a systematic review conducted in Iran in 2015, ASB prevalence in pregnant women was reported to be 13% (95% CI: 9–7) [ 65 ] after combining 20 articles (sample size: 15,108). In the present meta-analysis combining 31 studies with a sample size of 20,309 Iranian pregnant women, the prevalence of ASB was 8.7% (95% CI: 7.2–10.4). The strengths of this study compared to previous published meta-analyses include bigger sample size, the use of cross-sectional studies, excluding studies with a non-randomized sample [ 66 , 67 ] and removal of the duplicate articles that published the results more than once [ 14 , 16 , 68 , 69 ]. Each of the suggested factors can affect the final evaluation and accuracy of the prevalence while this was not considered in the previous meta-analyses [ 65 ].

The prevalence of ASB in pregnant Iranian women based on trimester of pregnancy shows that the highest prevalence occurs in the first trimester of pregnancy (11.7% [95% CI: 7.9–16.9]). Given that screening for UTI is done before the pregnancy and at 6–10 weeks of gestation in Iran, lack of care before pregnancy may increase the risk of UTI in pregnant women in the first trimester. However, trimester of pregnancy can be one of the causes of diverse prevalence of ASB in Iranian studies ( P = 0.02).

There seem to be a geographical variation in the ASB prevalence, and we could not find the causes, but a possible reason might include differences in race (there is much racial diversity in Iran), socioeconomic factors, education, quality health care and women’s health services communities [ 70 , 71 ].

The prevalence of ASB among pregnant women in other countries, including India (7.3%), Nigeria (24.7–45.3%), Nepal (8.7%) Bangladesh (10.2%) and Ethiopia (21.2%) was reported to be different [ 71 , 72 , 73 , 74 , 75 ].

The prevalence of UTI among young women is about 1–3% [ 76 ]. The results of this meta-analysis showed that the prevalence of UTI in pregnant Iranian women is high. Pregnant women prone to UTI are at risk for prematurity, preterm delivery, low birth weight, hypertension/pre-eclampsia, anemia, maternal and perinatal death associated with amnionitis [ 75 , 76 ].

Studies show that the higher the education level, the lower the frequency of this problem. Hence, the need for education and awareness of pregnant women, especially in those with a lower education level, is necessary [ 18 , 19 , 20 ].

A common organism of ASB in pregnant women in Iran was E.coli (63.2%). In other studies, the most common organism of ASB in women was E.coli [ 77 ]. E.coli is the underlying cause of ASB in 77% of sexually active young American women [ 78 ], 72% of girls of school age [ 79 ], and 65–84% of pregnant women [ 80 , 81 , 82 , 83 ].

E. coli strains isolated from healthy women without symptoms may have a lower frequency of virulence factors, such as adhesions, specific lipopolysaccharide, toxins, mobility factors, and other proteins compared to strains isolated from symptomatic urinary tract infection [ 84 , 85 ].

The aim of ASB treatment is to maintain sterile urine without causing toxicity in mother or fetus during pregnancy [ 82 ]. However, the best way to achieve this is not clear yet. In low-income countries, the situation is worse due to lack of information about the resistance to drugs used for UTI in pregnancy, drug costs and lack of access to information regarding the safety and efficacy of newer antibiotics [ 86 ].

In Iran, drug resistance in antibiotics used for UTI is a controversial topic. Different levels of antibiotic resistance and sensitivity has been reported in different studies. For example, in a study by Enaiat et al., high resistance of nalidixic acid, tetracycline and co-trimoxazole and low sensitivity of ampicillin, gentamicin and amikacin to E. coli has been reported in regard with bacteriuria in pregnant women [ 87 ]. However, in the study of Saffar, E.coli was highly sensitive to gentamicin and amikacin and less sensitive to trimethoprim-sulfamethoxazole and ampicillin. Therefore, considering the importance of empiric therapy for physicians, conducting a systematic review and meta-analysis to determine patterns of microbial resistance to drugs against UTI in Iran seems necessary.

Limitations

Lack of “AND” and “OR” operators support for a combined search in national databases.

Failure to investigate the prevalence of UTI based on trimester of pregnancy due to the limited number of studies.

Failure to investigate the prevalence of UTI based on factors such as multiple pregnancies, age, previous history of UTI, diabetes, anatomical abnormalities of urinary tract, lack of personal hygiene and socioeconomic status

UTI and ASB are highly common in pregnant women in Iran and the most common type of UTI is ASB. Therefore, it is recommended that urine culture be conducted as a part of routine tests for pregnant women. Moreover, pregnant women need to be provided with complete information about UTI complications during their pregnancy. The most common microorganisms involved in the etiology of ASB and UTI in pregnant women in Iran are E.coli and Staphylococcus . Since women and mothers’ health is the foundation of the family and the public health, making better management decisions for prevention, screening and treatment of this problem is recommended.

Abbreviations

Asymptomatic Bacteriuria

Iranian Research Institute for Information Science and Technology

Preferred Reporting Items for Systematic Reviews and Meta-Analyses

Regional Information Center for Science and Technology

Scientific Information Database

Urinary tract infection

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MA, SHA and ZJ performed data extraction. MA and LM performed statistical analysis. MA and SHA wrote the manuscript. ZJ, GHB, MA, MSH and MM performed the literature search and quality evaluation. SHA, GHB, MSH, and MM revised the manuscript. All authors read and approved the final manuscript.

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Azami, M., Jaafari, Z., Masoumi, M. et al. The etiology and prevalence of urinary tract infection and asymptomatic bacteriuria in pregnant women in Iran: a systematic review and Meta-analysis. BMC Urol 19 , 43 (2019). https://doi.org/10.1186/s12894-019-0454-8

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Received : 02 July 2018

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Published : 30 May 2019

DOI : https://doi.org/10.1186/s12894-019-0454-8

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Asymptomatic bacteriuria
Pregnant women

BMC Urology

ISSN: 1471-2490

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Urinary tract infection in pregnant women: an integrative review

Larissa Botelho da Silva Centro Universitário do Vale do Ipojuca/Wyden https://orcid.org/0000-0002-4400-6565
Pâmella Grasielle Vital Dias de Souza Centro Universitário do Vale do Ipojuca/Wyden https://orcid.org/0000-0001-9884-9544

Urinary tract infections (UTI) are considered the most frequent clinical complication in pregnancy, it arises due to a failure in the defense system against installed agents that can cause injuries of varying degrees for both the mother and the fetus. The present study points out the main microbiological agents, clinical classifications, complications arising and therapeutic approaches. An integrative literature review was carried out, using articles published between 2016 and 2021, in Portuguese, English and Spanish, which were published in full in the PubMed, SciELO and LILACS databases. UTIs in pregnancy are caused by hormonal, anatomical and physiological factors, these conditions promote the bacterial growth of this pathology. These infections are usually caused by bacteria from the intestinal microbiota that contaminate the urinary tract, with Escherichia coli standing out most predominantly in 80% of cases. For an effective treatment it is necessary to determine the bacteria causing the infection, to select the appropriate antibiotic. Therefore, to reduce and control cases of tract infections, prenatal consultations and early examinations to diagnose the infection should be carried out in order to prevent possible perinatal and maternal complications.

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