Asymptomatic bacteriuria during pregnancy: prevalence, antibiotic susceptibility and relationship with demographic factors

Original Article Asymptomatic Bacteriuria During Pregnancy: Its Prevalence, Antibiotic Susceptibility and Its Relationship with Demographic Factors Lebriz Hale AKTÜN 1 , Nilay KARACA 2 , Yaşam Kemal AKPAK 3 1 Medipol University Faculty of Medicine, Gynecology and Obstetrics, İstanbul, Turkey 2 Gaziosmanpaşa Medicalpark Hospital, Gynecology and Obstetrics, Istanbul, Turkey 3 Dışkapı Yıldırım Beyazıt Training and Research Hospital, Gynecology and Obstetrics, Ankara, Turkey Bezmialem Science ; : – DOI: 10.14235/bs.2017.1772 Keywords: Pregnancy, asymptomatic bacteriuria, prevalence, antibiotic susceptibility, risk factors Abstract Objective: Our aim is to determine the prevalence of asymptomatic bacteriuria (ABU), the most common microorganism, and antibiotic susceptibility in pregnant women who come to the obstetrics clinic in our region. Material and methods: Our study was conducted with 980 pregnant women who came to antenatal visit before the 20th gestational week. Patients with symptoms of urinary tract infection, suprapubic pain, painful urination, frequent urination, urinary incontinence and vaginal discharge and bad smell, patients using active antibiotics or have used them in the last month, medical history of kidney disease, history of kidney stones Patients with gestational diabetes mellitus and pregnant women were excluded from the study. A culture was taken from the middle urine and an antibiogram was performed. Pregnant women with bacteriuria were treated for 7 days with an antibiotic to which the agent was sensitive, according to the antibiogram results. Results: It was observed that 749 pregnant women screened for ABU did not differ in terms of age, gravida, parity and sexual activity. ABU was detected in 53 (7.1%) of 749 pregnant women included in the study. E. coli was the most frequently isolated microorganism in 36 (69%) of 53 pregnant women with ABU. E. coli was 99.3% sensitive to fosfomycin and 85% sensitive to cefuroxime. The second most frequently isolated microorganism, Klebsiella pneumoniae, was found to be susceptible to fosfomycin at a rate of 86%, and to cefepime and ceftriaxone at a rate of 100%. Enterococcus spp. was found to be 100% sensitive to ampicillin and fosfomycin. Conclusion: The prevalence of ABU is significantly higher during pregnancy. Since it is a clinical picture that poses a risk for miscarriage and premature birth, it is recommended to be screened. The most appropriate screening weeks are performed with a midstream urine culture at the beginning of the second trimester. Fosfomycin can be preferred in the treatment due to its high sensitivity to the causative microorganisms, easy use and safety. Asymptomatic Bacteriuria During Pregnancy: Its Prevalence, Antibiotic Susceptibility and Its Relationship with Demographic Factors Objective: Our aim is to determine the prevalence of asymptomatic bacteriuria (ABU), the most common microorganism, and antibiotic susceptibility in pregnant women who come to the obstetrics clinic in our region. Material and methods: Our study was conducted with 980 pregnant women who came to antenatal visit before the 20th gestational week. Patients with symptoms of urinary tract infection, suprapubic pain, painful urination, frequent urination, urinary incontinence and vaginal discharge and bad smell, patients using active antibiotics or have used them in the last month, medical history of kidney disease, history of kidney stones Patients with gestational diabetes mellitus and pregnant women were excluded from the study. A culture was taken from the middle urine and an antibiogram was performed. Pregnant women with bacteriuria were treated for 7 days with an antibiotic to which the agent was sensitive, according to the antibiogram results. Results: It was observed that 749 pregnant women screened for ABU did not differ in terms of age, gravida, parity and sexual activity. ABU was detected in 53 (7.1%) of 749 pregnant women included in the study. E. coli was the most frequently isolated microorganism in 36 (69%) of 53 pregnant women with ABU. E. coli was 99.3% sensitive to fosfomycin and 85% sensitive to cefuroxime. The second most frequently isolated microorganism, Klebsiella pneumoniae, was found to be susceptible to fosfomycin at a rate of 86%, and to cefepime and ceftriaxone at a rate of 100%. Enterococcus spp. was found to be 100% sensitive to ampicillin and fosfomycin. Conclusion: The prevalence of ABU is significantly higher during pregnancy. Since it is a clinical picture that poses a risk for miscarriage and premature birth, it is recommended to be screened. The most appropriate screening weeks are performed with a midstream urine culture at the beginning of the second trimester. Fosfomycin can be preferred in the treatment due to its high sensitivity to the causative microorganisms, easy use and safety. Introduction: Urinary tract infection is the most common bacterial infection requiring treatment during pregnancy (1). The risk of infection increases due to physiological and anatomical changes such as ureter dilatation during pregnancy, decrease in urethral peristalsis and bladder tone, increase in plasma volume, decrease in urine concentration, increase in urinary estrogen and progestin (2). Asymptomatic bacteriuria (ABU) is defined as the detection of at least 105 organisms/ml in the urine culture taken from the midstream urine in a patient who does not have any local or systemic symptoms of the urinary system (3). It is seen in 2-15% of pregnant women, and the most important etiological agent is coliform bacteria, especially Escherichia coli (E. coli), as in non-pregnant women (4). If ABU is not treated, it can cause either symptomatic acute cystitis and acute pyelonephritis in the later weeks of pregnancy at a rate of 20-40%. Otherwise, the rate of development of these clinical pictures is around 1% (5). Maternally infective condition can progress to sepsis and respiratory distress. Fetal complications are undesirable clinical pictures such as premature rupture of membranes, preterm birth, low birth weight infant and intrauterine growth retardation (IUGG) (6,7). Biological variations and geographic locations were also thought to be effective among the factors affecting the prevalence (5). Our aim in this prospective study is to determine the prevalence of ABU, the most common microorganism and antibiotic susceptibility of microorganisms in pregnant women who come to the obstetrics and gynecology clinic in our region. Materials and methods: Our study was conducted with 980 pregnant women who came to antenatal visit before 20 weeks of gestation and whose consent was obtained between 2014 and 2016. Hospital local ethics committee approval was obtained. Patients with symptoms of urinary tract infection, suprapubic pain, painful urination, frequent urination, urinary incontinence and vaginal discharge and bad smell, patients using active antibiotics or have used them in the last month, medical history of kidney disease, history of kidney stones Patients with gestational diabetes mellitus and pregnant women were excluded from the study. Except for routine antenatal tests, urine was collected from the middle urine and cultured within 2 hours for 749 pregnant women who remained after the patients who were excluded from the study. Microorganisms were cultured in urine with standard loop (semiquantitative method) using CLED (cystein lactose electrolyte deficient) medium/MacConcey and blood agar. Cultures were read 24 hours after aerobic incubation at 37°C. Samples were reincubated for another 24 hours before a negative result. Finding a single organism >105 organisma/ml in the results was accepted as bacteriuria. Pathogens were isolated and antibiogram was performed with standard antibiotic susceptibility test E. coli ATCC 25922 and S. aureus ATCC 25923. Multiple organisms were considered as contamination and the tests were repeated. Pregnant women with bacteriuria were treated with sensitive antibiotics known to be safe during pregnancy for 7 days. Descriptive and analytical statistics were performed for all patient records using the SPSS 21.0 (Statistical Package for the Social Sciences Inc.; Chicago, IL, USA) package program. Descriptive statistics were presented as mean±standard deviation, minimum-maximum values ​​for continuous-measure variables, and as the number of cases and percentage (%) for the numerical variables. Student’s t test was used to determine whether there was a statistically significant difference between the groups in terms of normally distributed continuous measurement variables, and the significance of the difference for non-normally distributed continuous measurement variables was evaluated with the Mann Whitney U test. Values ​​with P< 0.05 were considered statistically significant. Results: Demographic characteristics of 749 pregnant women screened for ABU are summarized in Table 1. There was no statistically significant difference between the two groups in terms of age, gravida, parity and sexual activity. Although it was not statistically significant in terms of hemoglobin levels, it was found to be higher in the ABU patient group (Table 1). ABU was detected in 53 (7.1%) of 749 pregnant women included in the study. E. coli was the most frequently isolated microorganism in 36 (69%) of 53 pregnant women with ABU (Table 2). The most frequently isolated microorganism was found to be susceptible to E. coli fosfomycin at a rate of 99.3% and to cefuroxime, the most commonly used antibiotic group during pregnancy, at a rate of 85%. The second most frequently isolated microorganism, Klebsiella pneumoniae (K. pneumoniae), was found to be 86% susceptible to fosfomycin and 100% to cefepime and ceftriaxone. Enterococcus spc, one of the gram-positive microorganisms isolated in the third frequency. was found to be 100% sensitive to ampicillin and fosfomycin (Table 3-4). Discussion: In this prospectively designed study, we found the prevalence of ABU in our pregnant population to be 7.1%, the most common microorganism was Escherichia coli, and the antibiotic to which it was most sensitive was fosfomycin. There is still no clear consensus in the world for the screening of ABU in pregnant women. According to the result of a 2016 review, there was no randomized controlled study evaluating the benefits and harms of ABU screening (2). However, the United States Preventive Services Task Force definitely recommends screening for ABU between the 12th and 16th weeks of pregnancy (8). In general, this screening is considered cost-effective compared to complications. While the average cost for ABU is $2.20 per patient, the cost for preterm birth or IUGG has been found to be $40-46 per case (9). In a large series of ABU prevalence studies conducted in our country, ABU was found at a rate of 8.5% (4). In our study, this rate was 7.1%. In the meta-analysis of studies originating from Iran, an average rate of 13% was found (10). Urinary tract infection [14.6% (Tanzania), 11.6% (Ethiopia)] is frequently observed in countries with low socioeconomic status where antenatal care is not sufficient, such as African countries (11,12). However, in studies conducted in this region, it was observed that sociodemographic characteristics did not contribute to these infections. In our study, no significant data were found in terms of the contribution of demographic data to ABU or being a related risk factor (11,13). Microorganisms with similar priority were observed in our country as well as in the world. In our study, E. coli was the first with 69%, and K. pneumoniae was the second most common with 15%. In another study conducted in our country, in which around 2000 patients were screened, E. coli was found in the first place with a percentage of 76.6%, and K. pneumoniae was in the second place with a rate of 14.6%, with figures similar to our study (4). In a study conducted in North India, Escherichia coli was the most frequently detected microorganism with 37.6%, while Enterococcus spp. It was the second most common microorganism with 21.1% (14). In another study, the detection rate of E. coli was 42.4%, while the second most common microorganism was Staphylococcus aureus with a rate of 39.3% (13). One of the reasons why this microorganism is the most common bacterium in bacteriuria is that it plays a role in increasing the pathogenicity of E.coli with the increase in estrogen concentration in the urine due to physiological changes occurring during pregnancy (15). If ABU is treated during pregnancy, it reduces the incidence of pyelonephritis that may develop in the future by 75%, and reduces the urinary tract infection that may develop later by 80-90% (8). For this reason, whether symptomatic or not, bacteriuria should be treated during pregnancy (1). Antimicrobial therapy should be chosen properly in terms of maternal and fetal safety. Due to the physiological changes in pregnant women, the dose of the selected antibiotic should be adjusted. As the renal filtration rate increases in pregnant women, the urine concentration decreases. Antibiotics with high urinary concentration and low serum concentration are more preferred (2). As a result of the first review and meta-analyses, no treatment modality has proven superiority. Therefore, it is recommended that the clinician decides based on price, accessibility and the best side-effect profile (8). Ampicillin/amoxicillin, nitrafurantoin and oral cephalosporins are recommended in the literature according to their relative cure rates, safety and high concentrations in urine (8). As detected in our study, high resistance to ampicillin and amoxicillin was observed. Oral cephalosporins may cause continuation problems for patients due to their long treatment regimens (16). Nitrofurantoin has been used in pregnancy for many years. There are even obstetricians who use it as a daily dose. In a randomized controlled study investigating this situation, a one-day treatment regimen and a seven-day treatment protocol were compared, and long-term treatment was found to be more effective (17). However, although nitrofurantoin is effective, it causes maternal hemolytic anemia in glucose 6 phosphate dehydrogenase enzyme deficiency. In addition, when looking at the safety scale of other antimicrobial agents, it should be kept in mind that tetracycline may cause fetal malformation and maternal acute liver failure, chloramphenicol may cause fetal toxicity, fluoroquinolones may cause fetal cartilage malformations and renal toxicity, and aminoglycosides may cause both maternal and fetal ototoxicity and nephrotoxicity (6,8). When evaluated in terms of antibiotic susceptibility tests and safety profile, the most preferred antimicrobial agent is fosfomycin (4,16). Antimicrobial agents included in FDA approved category B (no evidence of human risk) recommended for the treatment of lower urinary tract infections and asymptomatic bacteriuria in pregnancy without the need for special dose adjustment are penicillins, oral cephalosporins and fosfomycin tromethamine. The most important factor in the recommendation and preference of this group is that they prevent the synthesis of the cell wall, which is only present in the structure of bacteria, which is not present in humans (18,19). Fosfomycin trometamol, which was first obtained from Streptomyces cultures in Spain in 1969 and formerly called phosphonomycin, is one of the rare antibacterial agents in the world where the incidence of resistance in Escherichia coli strains remains extremely low, although it has been used in the treatment of various infections for many years (20). In our study, it stands out from other agents with its high sensitivity rates. In addition, it is emphasized that drugs with a resistance rate of 20% in the population should no longer be used in empirical treatment regarding the antibiotics to be included in the treatment algorithms. (21). One of the most important limitations of our study is that we only looked at the growth in urine culture once. The study may be more meaningful in groups consisting of pregnant women with ABU who have more cases and were diagnosed with the growth of the same microorganism in at least 2 consecutive cultures. In addition, the lack of maternal and fetal outcomes of the cases is another limitation in making comments. In conclusion, ABU is a condition with a high prevalence in pregnancy. Since it is a clinical picture that poses a risk for miscarriage and premature birth, it is appropriate to be screened. The most appropriate screening period may be at the beginning of the second trimester in order to minimize these risks. Although it is recommended to do it preferably twice, it can be diagnosed at least once with a midstream urine culture. Fosfomycin can be preferred as a treatment because of its high sensitivity, ease of use and safety. Sources: 1-Macejko AM, Schaeffer AJ. Asymptomatic Bacteriuria and Symptomatic Urinary Tract Infections During Pregnancy. 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