Introduction
Urinary tract infection (UTI) is one of the most common bacterial infections during pregnancy. It can be symptomatic or asymptomatic. Increased risk of UTI in pregnant women is due to anatomical changes and physiological adaptations during pregnancy.1 Untreated asymptomatic bacteriuria (ASB) in pregnancy predisposes to symptomatic UTI in 25% of infected women.2 Early diagnosis and appropriate treatment of ASB curbs the risk of pyelonephritis, ecclampsia, preterm delivery and adverse fetal outcomes. This prospective study was conducted to determine the occurrence of ASB, its etiological agents and their antibacterial susceptibility pattern in selected group of pregnant women.
Materials and Methods
The present study was carried out on in department of Microbiology at ESIC medical college, Telangana from September 2016 to March 2017. Study population included total of 346 antenatal women of gestational ages 28 weeks or less with no symptoms of urinary tract infection (UTI) attending for antenatal checkup. Patients with fever, incontinence or renal stones, diabetes, hypertension, recent history of antibiotic intake were excluded from study. Data regarding age, gravida, trimester, associated risk factors were obtained from standard proforma in requisition form filled by clinician. Clean catch midstream urine sample were cultured and identified by standard microbiological methods. Semi-quantitative culture of urine samples was done on blood and MacConkey agar by standard loop technique.3 Growth was interpreted as significant in Gram negative bacteria if colony count was >= to 105 colony forming unit per milliliter (CFU/ml) of urine. In Gram positive bacteria colony count of 102 CFU/ml of urine was considered significant. All bacterial isolates showing significant growth were identified by standard biochemical methods. 4 The antibiotic sensitivity testing (AST) of the isolates was be done by Kirby Bauer method according to CLSI guidelines.5
Result
Among total of 346 antenatal women screened 85.5% samples were sterile. Significant bacterial growth was found in 38 (11%) cases, 12(3.5%) cases showed insignificant growth of mixed bacterial flora. The age, gravida and trimester of participants did not have any statistical significance on ASB in present study. Escherichia coli (42.1%) and Enterococcus faecalis (42.1%) were most common isolates followed by Staphylococcus aureus (7.9%), Klebsiella pneumonia (5.3%) and Enterobacter aerogenes (2.6%) (Table 1). Antibiotic sensitivity pattern of most common gram negative bacteria, Escherichia coli revealed good sensitivity to cefotaxime (93.75%), amikacin (87.5%), nitrofurantoin (87.5%) and cotrimoxazole (81%). Sensitivity to ampicillin (25%), cefazolin (37.5%), amoxyclav (56%), norfloxacin (68.75%) and ciprofloxacin (75%) was reduced (Table 2). Antibiotic sensitivity pattern of most common gram positive bacteria, Enterococcus faecalis showed good sensitivity of 75% to nitrofurantoin and 67.5% to ampicillin, ciprofloxacin and high level gentamicin. Staphylococcus aureus showed 100% sensitivity to betalactam antibiotics and aminoglycoside (Table 3).
Table 1
Bacterial agents isolated
Table 2
Antibiotic sensitivity pattern of Gram negative bacteria
Table 3
Antibiotic sensitivity pattern of Gram positive bacteria:
Discussion
Urinary tract infections are most common infections in females especially in pregnancy. ASB in pregnancy is known to cause grave obstetric complications. Hence it is very important to screen all pregnant women for bacteriuria in every trimester and administer appropriate treatment in order to prevent perinatal and maternal complications. Incidence of ASB in our study was 10.9%. Different Indian and international studies showed incidence range of ASB as 2 to 50%.12, 11, 10, 9, 8, 13, 7, 6 (Table 4) Difference in incidence in studies across the world and in same country is due to differences in geographical location, social behavior, level of education, study population and sample size of participants. The age, gravida and trimester of participants did not have any statistical significance on ASB in present study. The reason for age distribution not having significant association with ASB in present study may be due to the factor that majority of antenatal women enrolled in this study belonged to 20-30 years than those between 31-45 years age group. The parity and gestational age not having significant association with ASB in present study correlated with previous researchers.15, 14, 12 In present study both Gram negative and Gram positive bacteria were predominantly responsible for ASB during pregnancy. The most common Gram negative uropathogen was Escherichia coli (42.1%). Different studies done by Verma et al, 6 Sujatha et al, 7 Chandel et al, 8 Shalima et al,9 Ali et al 10 and Bose et al 11 showed Escherichia coli as most common uropathogen. The most common Gram positive uropathogens was Enterococcus feacalis (42.1%). This finding was in agreement with other studies. 16, 15, 9, 6 Escherichia coli and Enterococcus fecalis are fecal flora that colonize the periurethral area. Profound anatomical and physiological changes during pregnancy result in urinary stasis and dysfunctional vesico-ureteral reflux that aid in UTI by fecal flora. Antibiotic sensitivity pattern of gram negative uropathogens showed good susceptibility to nitrofurantoin, cotrimoxazole, cefotaxime and aminoglycosides. Frequently prescribed antibiotics like amoxyclav, cefuroxime and norfloxacin showed increased resistance due to selective antibiotic pressure. Antibiotic sensitivity pattern of Enterococcus feacalis showed good susceptibility to nitrofurantoin, moderate sensitivity to routinely prescribed antibiotic like amoxyclav, amikacin, ciprofloxacin and poor susceptibility to norfloxacin. Antibiotic sensitivity pattern of Staphylococcus aureus showed good susceptibility to beta-lactam antibiotics. Antibiotic susceptibility pattern varies from one region to other based on local factors like overt or inappropriate use of selected antibiotics, patient compliance, over the counter availability and prescription of antibiotics without laboratory guidance.
Conclusion
Every pregnant woman in each trimester should have a urine culture done and detected cases should be treated according to the antibiotic susceptibility test. In present study both gram negative and gram positive bacteria were predominantly responsible for ASB. Culture plays a pivotal role as choice of antibiotic varies with the uropathogen isolated. Increasing resistance to commonly used antibiotics shows selective pressure due to their increased prescription. Antibiotic susceptibility testing will aid policy makers to determine the antibiotics to be used for ASB thereby reducing the perinatal and maternal morbidity and mortality.
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