Asymptomatic bacteriuria (ASB) refers to the presence of significant bacterial counts (≥10⁵ CFU/mL) in the urine of individuals who do not exhibit clinical symptoms of urinary tract infection (UTI). During pregnancy, physiological changes such as urinary stasis, ureteral dilation, and decreased bladder tone make the urinary tract more susceptible to colonization by pathogens [1]. If left untreated, ASB can progress to symptomatic infections like pyelonephritis and is associated with complications including preterm labor, low birth weight, and increased perinatal morbidity and mortality [2,3]. Global prevalence rates of ASB in pregnancy vary widely, ranging from 2% to over 20%, influenced by geographic, demographic, and healthcare-related factors. A multicenter study in Pakistan reported a prevalence of 26.5%, with Escherichia coli being the most common isolate [4]. In Ghana, the prevalence was found to be 7.3% [5], while a study in Egypt noted a prevalence of 14% [6]. Similarly, a Saudi Arabian study in Jeddah reported a rate of 13% among antenatal women [7]. These figures underscore regional disparities and the need for localized data to guide clinical practice.

The clinical importance of ASB screening is well established. Verma et al. found a significant association between untreated ASB and adverse perinatal outcomes such as preterm birth and low birth weight in an Indian cohort [3]. Cochrane reviews and expert guidelines recommend screening and treating ASB during early pregnancy to reduce the risk of maternal and neonatal complications [2]. Despite this, routine screening is not universally practiced, especially in resource-limited settings, due to financial and infrastructural constraints. Given the substantial evidence linking ASB with adverse outcomes and the regional variation in prevalence, this study aims to determine the prevalence of asymptomatic bacteriuria among pregnant women attending antenatal clinics in a tertiary care hospital in Navi Mumbai. This will contribute to the regional evidence base and potentially support the integration of routine ASB screening in antenatal care programs.

This descriptive cross-sectional study was conducted in the Department of Obstetrics and Gynecology at a tertiary care hospital. A total of 200 pregnant women attending routine antenatal check-ups were enrolled over a defined study period using consecutive sampling. Inclusion criteria included all pregnant women, irrespective of gestational age, who were asymptomatic for urinary tract infection (UTI). Women with symptoms of UTI, those who had received antibiotic treatment in the last 72 hours, and those with known urinary tract anomalies or chronic kidney disease were excluded from the study.

Following informed written consent, demographic and clinical data were collected through structured interviews and clinical examination. Variables recorded included age, parity, gestational age, presence of anemia (defined as hemoglobin <10 g/dL), and maternal morbidity indicators. Midstream clean-catch urine samples were obtained under aseptic conditions from all participants. The samples were analyzed microscopically and cultured using standard microbiological techniques. Asymptomatic bacteriuria (ASB) was diagnosed based on the presence of ≥10⁵ colony-forming units (CFU)/mL of a single uropathogen in the absence of urinary symptoms. Urine microscopy for pus cell count and dipstick testing for proteinuria (urine albumin) were also performed.

Antibiotic susceptibility testing for isolates was conducted using the Kirby-Bauer disk diffusion method in accordance with CLSI guidelines. Patients diagnosed with ASB were treated based on culture sensitivity. The antibiotics used included Nitrofurantoin (50%), Ampicillin (22.7%), Amoxicillin (9.1%), Cephalexin (9.1%), and Cefuroxime (9.1%). Follow-up cultures were performed post-treatment to evaluate the microbiological cure, with 90.9% showing no culture growth, and 9.1% showing persistence of organisms.

Maternal outcomes such as threatened abortion, preterm labor, premature rupture of membranes (PROM), and puerperal complications (fever, wound infection, symptomatic UTI) were recorded. Neonatal outcomes assessed included low APGAR scores, intrauterine growth restriction (IUGR), low birth weight, and NICU admissions. Ethical approval was obtained from the Institutional Ethics Committee prior to the initiation of the study. Data analysis was performed using IBM SPSS Statistics version 26.0. Results were expressed in terms of frequencies and percentages, and presented using descriptive tables and bar charts to illustrate the prevalence of ASB and its associations.

The analysis of Table 1 presents the prevalence of Asymptomatic Bacteriuria (ASB) among pregnant women across multiple clinical and demographic variables. Among age groups, the highest prevalence of ASB was observed in women aged 23–27 years (12.9%), followed by the 28–32 years group (10.0%), while no cases were noted in the 33–35 years group. ASB prevalence was slightly higher in primigravida women (11.3%) compared to multigravida women (10.5%). Regarding gestational age, ASB was most frequent in the third trimester (11.8%) followed by both first and second trimesters (10% each). Urine albumin levels showed a positive association with ASB. While only 9.6% of those with negative albumin had ASB, the prevalence sharply increased in subjects with trace (22.2%) and 3+ albumin (50%). Similarly, pus cell count also correlated with ASB: women with 6–9 pus cells had a prevalence of 12.5%, those with ≥10 pus cells had 10.7%, and those with ≥5 pus cells had 10.5%.

In terms of anemia status, ASB was more prevalent among anemic women (13.7%) compared to non-anemic women (10.1%). Among maternal morbidity factors, the highest prevalence of ASB was observed in subjects with PROM (25%), followed by those with pre-term labor (13.3%) and no maternal morbidity (13.9%). Threatened abortion and threatened pre-term groups showed lower ASB rates (3.8% and 2.8%, respectively). Regarding maternal outcomes, puerperal fever had the highest ASB prevalence (18%), followed by wound infection (14.3%) and normal puerperium (9.0%), while symptomatic UTI had the lowest at 5%. Overall, the data suggest that certain clinical factors—particularly elevated urine albumin, presence of pus cells, anemia, PROM, and puerperal fever—are associated with higher ASB prevalence during pregnancy.

Table 2 presents the distribution of organisms isolated in cases of Asymptomatic Bacteriuria (ASB) among pregnant women. The most commonly isolated pathogen was Escherichia coli (E. coli), accounting for 50% of all ASB cases (11 out of 22 subjects). This highlights E. coli as the predominant uropathogen in pregnancy-related ASB. The second most frequent isolate was Klebsiella species, responsible for 23% of infections, followed by Group β Streptococci (GBS) and Citrobacter species, each contributing 9%. Less frequently isolated organisms included Enterococcus species and Coagulase-Negative Staphylococci (CONS), each comprising 5% of the cases. These findings underscore the importance of E. coli and Klebsiella as primary pathogens in the etiopathogenesis of ASB in pregnancy, which is crucial for guiding empirical antimicrobial therapy.

Table 3 summarizes the antibiotic sensitivity and resistance profiles of microorganisms isolated from pregnant women diagnosed with asymptomatic bacteriuria (ASB). The highest sensitivity was observed with Piperacillin + Tazobactam, with 95.5% of isolates susceptible, followed closely by Amikacin, which showed 90.9% sensitivity. Ampicillin and Amoxicillin also demonstrated good efficacy, with 81.8% sensitivity each. Among the first-line oral antibiotics, Cephalexin and Nitrofurantoin each had 72.7% sensitivity, indicating their continued relevance in empirical treatment. However, Cefuroxime showed slightly lower sensitivity (68.2%) and a moderate resistance rate of 27.3%. Norfloxacin, though effective in some cases, had the highest resistance rate among the listed antibiotics at 36.4%, and the lowest sensitivity (63.6%). Overall, the results suggest that Piperacillin + Tazobactam and Amikacin are the most effective antibiotics against ASB pathogens in pregnancy, while Norfloxacin may be less suitable due to its relatively high resistance rate. These findings emphasize the need for routine culture and sensitivity testing to guide targeted antibiotic therapy in pregnant women with ASB.

Table 4 highlights the follow-up bacteriological status and neonatal outcomes among pregnant women diagnosed with asymptomatic bacteriuria (ASB). In the follow-up of 22 ASB cases, 90.9% (n=20) showed no culture growth, indicating successful microbial clearance post-treatment. However, 4.5% (n=1) had persistence of the same organism (E. coli), and another 4.5% (n=1) grew Enterococcus sp., suggesting incomplete eradication or re-infection. With regard to neonatal outcomes, 59.1% of the neonates were born with normal parameters, while the remaining 40.9% experienced adverse outcomes. Specifically, 9.1% of neonates each had a low APGAR score, intrauterine growth restriction (IUGR), and low birth weight, and 13.6% required NICU admission. These findings reflect the potential risks that untreated or partially treated ASB can pose to neonatal health, reinforcing the importance of timely diagnosis, appropriate antibiotic treatment, and follow-up in pregnant women with ASB.

The present study reported an 11% prevalence of asymptomatic bacteriuria (ASB) among pregnant women, which is comparable to findings from Egypt (14%) [6], Saudi Arabia (13%) [7] , and India (9–13%) [3,8]. However, it is lower than the prevalence observed in Pakistan (26.5%) [4] and higher than that reported in Ghana (7.3%) [5] and Nigeria (6–10%) [9]. Such variations may be due to differences in sample size, cultural practices, hygienic standards, and screening methodologies used across different regions.

The predominance of Escherichia coli (50%) as the causative organism in ASB aligns with global and regional trends reported in multiple studies [3,4,10]. Klebsiella species (23%) and Group B Streptococci (9%) were also noted, which is consistent with earlier findings from Egypt, India, and Ethiopia [3,6,11]. The antibiotic sensitivity profile showed high susceptibility to Piperacillin + Tazobactam (95.5%) and Amikacin (90.9%), followed by Ampicillin and Amoxicillin (81.8% each). These findings are in line with studies by Smaill et al. and Kumalo et al. [2,12], emphasizing the effectiveness of these antibiotics in empirical therapy. Conversely, Norfloxacin exhibited the highest resistance (36.4%), echoing concerns raised in recent studies about increasing antimicrobial resistance among uropathogens [11,13].

Our findings also revealed clinical associations between ASB and anemia (13.7% vs. 10.1% in non-anemic women), elevated urine albumin levels, and increased pus cell counts—suggestive of subclinical inflammation or renal compromise. These results support previous studies that identified anemia and proteinuria as potential risk factors for ASB [3,8,12]. Furthermore, ASB prevalence was highest among women with PROM (25%), preterm labor (13.3%), and puerperal fever (18%), highlighting the maternal risks associated with undiagnosed ASB during pregnancy [6,10]. Neonatal outcomes showed that 40.9% of infants born to ASB-positive mothers experienced complications such as low birth weight, IUGR, and NICU admission. Similar neonatal outcomes have been reported by Verma et al. and Imade et al. [3,7], confirming the association between untreated ASB and adverse perinatal outcomes. These findings underscore the clinical importance of routine ASB screening in antenatal care to reduce preventable maternal and neonatal morbidity.

This study highlights a significant prevalence of asymptomatic bacteriuria (ASB) among pregnant women, with notable associations with anemia, elevated urine albumin, increased pus cell count, and specific maternal morbidities such as PROM and preterm labor. Escherichia coli emerged as the predominant uropathogen, and Piperacillin + Tazobactam and Amikacin were found to be the most effective antibiotics. The study also observed adverse neonatal outcomes, including low birth weight, IUGR, and NICU admissions in ASB-positive pregnancies. These findings underscore the importance of routine screening and timely treatment of ASB during pregnancy to prevent potential maternal and perinatal complications. Integrating ASB screening into standard antenatal care protocols, particularly in tertiary care settings, could substantially improve maternal and neonatal health outcomes.

This study highlights a significant prevalence of asymptomatic bacteriuria (ASB) among pregnant women, with notable associations with anemia, elevated urine albumin, increased pus cell count, and specific maternal morbidities such as PROM and preterm labor. Escherichia coli emerged as the predominant uropathogen, and Piperacillin + Tazobactam and Amikacin were found to be the most effective antibiotics. The study also observed adverse neonatal outcomes, including low birth weight, IUGR, and NICU admissions in ASB-positive pregnancies. These findings underscore the importance of routine screening and timely treatment of ASB during pregnancy to prevent potential maternal and perinatal complications. Integrating ASB screening into standard antenatal care protocols, particularly in tertiary care settings, could substantially improve maternal and neonatal health outcomes.

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