|Year : 2014 | Volume
| Issue : 1 | Page : 95-99
Asymptomatic bacteriuria among pregnant women with sickle cell trait in Enugu, South Eastern Nigeria
CC Obiora1, CC Dim1, HU Ezegwui1, EE Nwogu-Ikojo1, C Okeudo2
1 Departments of Obstetrics and Gynecology, University of Nigeria Teaching Hospital, Enugu, Nigeria
2 Department of Obstetrics and Gynecology, Imo State University Teaching Hospital, Orlu, Nigeria
|Date of Acceptance||18-Apr-2013|
|Date of Web Publication||10-Dec-2013|
C C Obiora
10 Cornerstone Avenue, P.O. Box 2752, Enugu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Context: Asymptomatic bacteriuria (ASB) in pregnancy is a major risk factor for developing acute cystitis and pyelonephritis, especially, among women with sickle cell disease. This study compared the prevalence, pattern, and microbiological characteristics of ASB in pregnancy between sickle cell trait (HbAS) and normal hemoglobin AA (HbAA) genotype subjects.
Materials and Methods: Culture and sensitivity of mid-stream urine samples were collected from 300 HbAS women and 300 matched HbAA control at the antenatal clinic of University of Nigeria Teaching Hospital Enugu, Nigeria from August 2010 to December 2011. Analysis was both descriptive and inferential at 95% confidence levels.
Results: Prevalence of ASB in HbAS and HbAA women were 32.7% (98/300) and 32% (96/300) respectively (odd ratio (OR) =1.03 [95% confidence interval (CI) 0.73, 1.45]). Escherichia coli was the most common organism isolated in both the HbAS group (56.1%, 55/98) and control group (61.4%, 59/96), (OR = 0.80 [95% CI 0.45, 1.42]). The antibiotics with the highest microbial sensitivity were ciprofloxacin 90.8% (89/98) and gentamicin 100% (98/98) for HbAS and HbAA women respectively.
Conclusions: The prevalence of ASB in pregnant women with HbAS in Enugu, Nigeria was high and did not vary significantly from that of woman with HbAA. Therefore, pregnant women irrespective of their sickle cell status would benefit from routine screening for ASB.
Keywords: Asymptomatic bacteriuria, Enugu-Nigeria, pregnant women, sickle cell trait
|How to cite this article:|
Obiora C C, Dim C C, Ezegwui H U, Nwogu-Ikojo E E, Okeudo C. Asymptomatic bacteriuria among pregnant women with sickle cell trait in Enugu, South Eastern Nigeria. Niger J Clin Pract 2014;17:95-9
|How to cite this URL:|
Obiora C C, Dim C C, Ezegwui H U, Nwogu-Ikojo E E, Okeudo C. Asymptomatic bacteriuria among pregnant women with sickle cell trait in Enugu, South Eastern Nigeria. Niger J Clin Pract [serial online] 2014 [cited 2020 May 30];17:95-9. Available from: http://www.njcponline.com/text.asp?2014/17/1/95/122856
| Introduction|| |
Pregnant women with sickle cell trait (HbAS) are thought to have a greater propensity for the development of asymptomatic bacteriuria (ASB), acute cystitis and pyelonephritis than pregnant women with normal hemoglobin AA (HbAA) genotype.  The term asymptomatic bacteriuria (ASB) refers to the presence of a positive urine culture in an individual in the absence of clinical signs and symptoms of urinary tract infection.  The diagnosis of this condition requires voided urine specimens and isolation of at least 10 5 colony forming units per milliliter of the same bacterial strain.  It has been shown that pregnancy does not increase the risk of ASB,  rather it enhances its progression to symptomatic disease;  therefore, ASB in pregnancy is a major risk factor for developing symptomatic urinary tract infection during pregnancy.  This complication is more common in pregnancy because of the relative obstruction by the gravid uterus and the dilatory effect of progesterone on the urinary collecting tracts;  thus, leading to multiplication and ascending of the bacteria to the upper urinary tract. Furthermore, although the HbAS is often considered to be benign, conditions such as hypoxia, hyperviscosity, dehydration, and acidosis may enhance sickling of red blood cells.  This increases the risk of vaso-occlusion particularly in the kidneys, where the relatively anoxic, acidotic and hypertonic milieu favor hemoglobin S polymerization and hemolysis as evidenced by elevated lactate dehydrogenase levels in the blood of such patients.  Furthermore, serum free iron released from sickle erythrocytes in the circulation leads to the accumulation of free iron in the urine increasing the risk of infection.  It is obvious therefore that maternal bacteriuria may be associated with increased maternal and fetal morbidity, and this risk may be higher for HbAS pregnant women. This study compared the prevalence of ASB, the pattern of bacterial agents and their antimicrobial susceptibility between pregnant women with HbAS and their HbAA counterpart.
| Materials and Methods|| |
This is a cross-sectional analytical study of two cohorts of consenting singleton pregnant women at the University of Nigeria Teaching Hospital (UNTH), Enugu, Nigeria, and Mother of Christ Specialist Hospital, Enugu, from August 2010 to December 2011. The study group was made of 300 consecutive women with HbAS while the control group comprised of 300 women with HbAA matched for age, parity, and gestational age groups. After recruiting an eligible woman for the study group, the next antenatal attendee with HbAA who matched the selected participants was recruited as the control. Exclusion criteria included sickle cell anemia, history of diabetes mellitus, symptoms of urinary tract infections or renal disease, history of antibiotics use or urethral catheterization within 2 weeks prior to the study. Hemoglobin electrophoresis was used for the sickle cell genotyping of pregnant women. Ethical approval for this study was obtained from the Health Research Ethics Committee of UNTH Enugu.
Following informed consent, each study participant was educated on how to collect a urine sample. Clean-catch midstream urine sample from each participant was collected into a sterile boric acid universal bottles after antero-posterior swabbing of the vulva using sterile gauze soaked in normal saline. ,, Each sample collection was supervised by one of the three nurses trained for the procedure. The urine samples were sent to the microbiology laboratory within one hour of collection. Each urine sample was thoroughly mixed by gentle shaking; afterward, a loop-full (using a standard wire loop) was streaked onto Blood agar, Cysteine Lactose Electrolyte Deficient medium and MacConkey Agar, and incubated aerobically at 37C for 24 h.  Counts of 10 5 organisms or more per milliliter of the urine samples were considered significant.  Such colonies were identified using standard methods thus: Colonial morphology, Gram reactions, sugar fermentation, catalase test, coagulase test, arginine deaminase test, oxidase test, indole, and urea hydrolysis test. , Sensitivity was determined using Kirby-Bauer disc diffusion technique.  The data obtained was analyzed by descriptive and inferential statistics using SPSS computer software version 16.0. Proportions were compared with Chi-square test and a P value of < 0.05 was considered statistically significant.
Participants' social classes were determined using their education status and their husbands' occupation. 
Enugu State is located in the South-East geo-political zone of Nigeria and it has a population of over 3 million.  A study among students in the state showed a HbAS prevalence of 11%. 
The UNTH Enugu is a teaching hospital owned by the Federal Government of Nigeria. The average antenatal attendance (first visits and revisits) of the hospital is 795 women/month. On the other hand, the Mother of Christ Specialist Hospital, Enugu is a faith based specialist hospital located in the capital city of Enugu State. Its average antenatal attendance is 703 women/month.
| Results|| |
The age range of the study and control groups was 15-49 years with a mean of 28.7 5.0 years and 27.9 4.8 years respectively (P = 0.765). The modal age group for both groups was 25-29 years.
Ninety eight urine samples from the study group showed significant culture as against 96 urine samples from the HbAA group, which gave ASB prevalence of 32.7% and 32.0% respectively. The observed difference was not statistically significant (odd ratio (OR) =1.03 [95% confidence interval (CI) 0.73, 1.45]).
Seven different types of bacteria were identified during the study; 4 (57.1%) out of these were isolated at varying proportions from both the HbAS and HbAA groups while the remaining 3 (42.9%) were isolated only from the urine samples from the control group [Table 1]. Furthermore, Escherichia More Details coli was the most common organism isolated in both the HbAS group (56.1%, 55/98) and control group (61.4%, 59/96); but the difference was not significant (OR = 0.80 [95% CI 0.45, 1.42]). Details of the distribution of bacterial isolates in the two groups are shown in [Table 1]. The antibiotics with the highest microbial sensitivity were ciprofloxacin (90.8%, 89/98) and gentamicin (100.0%, 98/98) for HbAS and HbAA groups respectively. On the other hand, ampiclox (2.0%, 1/98) and amoxicillin (2.1%, 2/96) had the least microbial sensitivity for the study and control groups respectively. Details of the antibiotics' microbial sensitivity are shown in [Table 2] and [Table 3].
|Table 1: Distribution of organisms isolated in the case and control groups |
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|Table 2: Antibiotic sensitivity pattern of organism isolated from cases (HbAS) |
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|Table 3: Antibiotic sensitivity pattern of organism isolated from control (HbAA) |
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When participants were stratified according to socio-economic class [Table 4], significant differences in the prevalence of ASB were observed between the HBAS group and the control group, in class 1 (28.2% vs. 55.2%, OR = 0.32 [95% CI 0.16, 0.64]); and class 4 (37.9% vs. 20.7%, OR = 2.34 [1.04, 5.24]). For the remaining social classes, the prevalence of ASB did not vary significantly between the two groups [Table 4].
| Discussion|| |
The modal age group of study participants was 25-29 years, which may suggest that it is the most reproductive age group for the pregnant women with HbAS in the study area. Previous reports on ASB in pregnancy noted wide variation of the prevalence ranging from 7% to 86.6%, ,,,,,,,,,,,, therefore, the prevalence of 32% found in this study may not be unexpected. The ASB prevalence in this study is lower than the findings from a related study by Thurman et al. in United States of America, which showed the prevalence of 47.5% and 46.9% among HbAS and HbAA respectively.  As in this study, the proportion of women with ASB was higher among the HbAS group when compared to the HbAA group, but the difference was not significant.  However, these two study findings did not support the report of a systematic review on hemoglobinopathy, which showed that the risk of bacteriuria was higher among pregnant women with hemoglobinopathies.  Furthermore, an earlier study had identified a lower ASB prevalence for the HbAS when compared with HbAA women (13.0% vs. 9.0%) and in this case, the observed difference was statistically significant.  This report was supported by a more recent study which showed that the prevalence of ASB among pregnant women with HbAS were significantly higher than that of HbAA women (13.9 vs. 10.8).  A critical review showed these two studies actually influenced the conclusion of the systematic review with respect to bacteriuria. Previous studies on ASB in pregnancy had shown a trend towards higher prevalence of ASB among women from lower socioeconomic classes; ,,,, this trend seemed to be the case among HbAS women in this study, but the pattern within the HbAA group was not definite. Furthermore, though this study showed that the prevalence of ASB did not vary between HbAS and HbAA women in general, appreciable differences seem to exist within the socio-economic classes [Table 4] for instance, within the socio-economic class one, pregnant women with ASB were about 3 times more likely to be HbAA when compared with HbAS women; conversely, women in class 4 who had ASB were about 2 times more likely to be HbAS than HbAA. Further studies are required to study the actual effect of socioeconomic status on ASB in pregnancy. Likewise, subsequent studies on the relationship between HbAS and ASB should control for socio-economic status. As expected, E. coli was the most common organism isolate from both study and control groups in this study. This finding is in keeping with the reports of previous studies on the subject, ,,,,,, except the study from Jos, Nigeria which recorded Staphylococcus aureus as the most common organism while E. coli was not isolated.  Furthermore, this study did not identify any statistical difference between the frequencies of E. coli isolated in both groups which is probably because E. coli is a fecal flora in human that also colonizes the periurethral area, thereby causing an ascending infection of the urinary tract.  In the decreasing order of frequency, the other organisms isolated from both groups included S. aureus, Klebsiella spp., and Enterobacter. Similar organisms and those of the same families were isolated in previous studies. ,,,,, This study suggests that ASB in HbAS women were less likely to be due to E. coli when compared to ASB in HbAA women [Table 1]. On the other hand, the odds of ASB in HbAS women due to S. aureus, was higher than that of HbAA women, though the observed difference was not significant. The microorganism pattern observed in this study will help in the determination of effective antibiotics for ASB prophylaxis among pregnant women.
It is not clear why Citrobacter, Streptococcus faecalis and Salmonella More Details spp. were isolated in the HbAA group only; a larger sample sized study may help confirm whether HbAS is protective against these organisms. Furthermore, bacteria isolated in both groups of this study were most sensitive to gentamicin and ciprofloxacin, but least sensitive to amoxycilin [Table 3] and [Table 4]. However, the observed sensitivity pattern in this study is at variance with the findings of earlier reports from the study area; , for instance, Ezeome et al. reported least microbial sensitivity to Ciprofloxacin among other drugs.  This change in pattern underscores the need for continuous monitoring of bacterial sensitivity pattern in our environment where antibiotics are procured freely over the counter. Unfortunately, the antibiotics to which the organisms isolated in this study were most sensitive to, fall into the category C of the United States Food and Drug Administration classification of antibiotics for the treatment of pregnant women with ASB. 
It is concluded that the prevalence of ASB among pregnant women in Enugu, Nigeria is high. Furthermore, pregnant women with HbAS do not have higher odds of developing ASB when compared to their counterparts with normal hemoglobin. Therefore, considering the known effects of ASB on pregnancy outcome, there is the need to initiate routine screening and treatment of ASB among pregnant women in the study area.
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[Table 1], [Table 2], [Table 3], [Table 4]