Prevalence, aetiology and antibiotic sensitivity profile of asymptomatic bacteriuria isolates from pregnant women in selected antenatal clinic from Nairobi, Kenya

Introduction Asymptomatic bacteriuria (ASB) is the presence of bacteria in urine without apparent symptoms of urinary tract infections. The importance of asymptomatic bacteriuria lies in the insight it provides into symptomatic infections. To determine prevalence, bacterial isolates and Antibiotic Sensitivity Profile of asymptomatic bacterial urinary tract infection in pregnant women in selected clinics in Nairobi. Methods This was a cross-sectional study involving women attending antenatal clinic at selected clinics of Nairobi County. The women who met the inclusion criteria were included in the study. The midstream urine samples of these women were subjected to microscopy, culture and sensitivity. Results A total of 1020 of women on their first antenatal clinic visit participated in the study; 219 of them had ASB, giving a prevalence of 21.5 % at 95% confidence level. Escherichia coli were the common organism isolated at 38.8%. The majority of the organisms were sensitive to imipenem and gentamycin. Conclusion There is a high prevalence of ASB among pregnant women included in the study from the Nairobi county clinics. Therefore, routine ASB screening of pregnant women is recommended among the women attending antennal clinics in Nairobi county clinics.


Introduction
Bacteriuria is the presence of bacteria in the urine. Bacteriuria is said to be significant in the presence of > 10 5 colony forming units (CFU)/ml or more of pure isolates [1,2]. The danger with bacteriuria is that it does not always present with symptoms [2].
However asymptomatic bacteriuria during pregnancy if left untreated, may lead to acute pyelonephritis, preterm labour, low birth weight foetus [3,4]. Profound physiologic and anatomic changes in the urinary tract during pregnancy contribute to the increased risk for infection [1,5]. E. coli is a significant causative agent given it accounts for 80% to 90% of UTIs [6]. Most UTIs are caused by bacteria and are treated by antibiotics. However there is increased development of microbial resistance to these antibiotics [7,8]. Drug resistance is an important phenomenon associated with increased treatment costs. A high proportion of the women who attend Nairobi county council clinics belong to the low socioeconomic class, have high parity, and reside in informal settlement setup. These have been demonstrated as risk factors for ASB by studies done earlier [9,10]. It was because of this that study was done in the selected clinics. This study aimed to determine the profile, prevalence, microbiological isolates, and risk factors of ASB among pregnant women in Riruta, Kangemi and Kahawa Soweto area. The findings from this study may encourage the commencement of routine urine culture, and sensitivity at clinics in the study centres. It may also help determine the types of antibiotics to be used on pregnant women who have ASB.

Study area
Nairobi, Kenya's capital city is a typical sub-Saharan Africa (SSA) urban centre characterized by population explosion with a current population of about 3.4 million in 2010 [11]. Majority of residents estimated at 60-70% of her population live in informal settlements [12]. The Nairobi county health clinics are distributed within the county and some cater for specialized needs like dental, skin and infectious conditions. Among the health clinics there are those that provide services from antennal to normal delivery. These are the ones we selected according their location in the informal settlement areas which are known risk factor for asymptomatic bacteriuria. The clinics run antenatal clinics on daily basis and all complicated cases are referred to specialized county hospital within Nairobi.

Study design
This was a cross-sectional study of pregnant women on their first antenatal clinic of the Nairobi county health centres. A questionnaire was used to obtain information from the study participants. The information obtained consisted of identification number, age, phone number, educational level, marital status, parity, gestational age, and human immune virus status. The inclusion criteria involved the first visits of apparently healthy pregnant women attending clinic for first the visit those who gave their informed consent to participate in the study. However, the women excluded from the study were those who had features of urinary tract infection, fever, had taken antibiotics within 2 weeks of the study, had medical chronic conditions (HIV) retroviral disease, and those who declined to consent despite adequate counselling. All pregnant women at the antenatal clinic, who met the inclusion criteria, were counselled on how to collect midstream urine. This involved initial instructions by the female attending trained nurses and laboratory technicians. The laboratory technicians supervised the urine-sample collection. The first part of the urine was voided, and approximately 10-15 mL of midstream urine was collected in a sterile universal bottle, that had been correctly labelled and given to the patients. The urine samples in the sterile universal bottles were taken to the laboratory for processing within 1 hour. These samples were subjected to culture, and sensitivity according to standard. Microscopy was done at the clinic involved centrifugation of approximately 10 mL of urine sample in a tube at 1,500 rpm. The sediments were poured on a clean slide and observed under a microscope for casts, pus cells, and yeast cells. The remaining urine was sent to processing laboratory for culture Samples were cultured on air dried plates of Cysteine lactose electrolyte deficient agar (CLED) using a calibrated loop delivering 0.002ml of urine. Plates were incubated aerobically at 37°C overnight. Colony counts yielding bacterial growth of 10 5 organism/ml or more of pure isolates were deemed significant.
Contaminated urine usually has less than 104organism/ml and often contains more than one bacteria species [13]

Data analysis
Data analysis was descriptive and multinomial logistic regression analysis was done at 95% confidence level using SPSS version 23.0 (IBM SPSS statistics Inc., Chicago, IL, USA). A P-value of less than or equal to 0.05 was considered statistically significant.

Sample size
The formula used for sample size calculation was n=z 2 (p (1p))/e 2 [15]. This study used an estimate of the proportion of population falling into the group of interest at 50%. The prevalence of asymptomatic bacteriuria in pregnancy in low socio-economic population and with specific inclusion criteria is unknown in Kenya.
This gave the minimum sample size at 384 however due large patient numbers that are attended at the clinics of interest the sample size was increased for better representation.

Ethical clearance
Ethical clearance for this study was obtained from the KEMRI Ethics Clearance Committee.

Results
A total of 1020 women visiting the antenatal clinic for first visit who met the inclusion criteria participated in the study. The age of the women included in this study ranged between 16 to 45years with a mean of 24.3±4.6 years (P=0.053). A total 219 of the participants had ASB, giving a prevalence of 21.5%(95 CI range 19.1-23.9%). Table 1 shows the prevalence of asymptomatic bacteriuria from cultured urine. Table 2 Table 3). The resistance and susceptibility pattern of gram positive and gram negative isolates from positive asymptomatic bacteriuria is shown in Table   4 and Table 5. All bacterial isolates had high resistance to ampicillin ranging from 83.3% to 100%. Imipenem had the lowest resistance to all isolates ranging from 0% to 10.2% and most isolates were susceptible to imipenem ranging from 89.7% to 100%. E. coli isolates from this study had resistance to most antibiotics tested except for imipenem. The resistance ranged from 11.6% for gentamycin and to 90.6% for ampicillin. This study found 18.8% resistance to ciprofloxacin by the E.coli isolates.

Discussion
The current study reported a prevalence of ASB among women attending antenatal clinic at selected clinic in Nairobi at 21.5%. The prevalence of asymptomatic bacteriuria is not uncommon during pregnancy. However the importance of asymptomatic bacteriuria lies in the insight it provides into symptomatic infections [16].
Asymptomatic bacteriuria may exist for short term in non-pregnant women but rarely resolves spontaneously during pregnancy [17].
The prevalence of asymptomatic bacteriuria does not change during pregnancy but there is change in pathogenesis, which keeps mother and baby at risk of complications due to urinary tract infection [1]. In this study there were some isolates which showed resistance to imipenem one (1) Klebsiella spp, four (4)  This study limitation was the health clinics based design catchment area, which may not be a true reflection of what is happening in Nairobi. However, it was strengthened by the random sampling of the health centres which was from three different sub counties.

Conclusion
In conclusion, there is a high prevalence of ASB among pregnant  The most common uropathogen was Escherichia coli;  A high rate of resistance to tetracycline, cotrimoxazole and ampicillin has been reported.

What this study adds
 Prevalence of asymptomatic bacteriuria in pregnant women without HIV/AIDS was found at 21.5% in Kenya in this study;  High resistance against third generation cephalosporin was observed in this study and one isolate was resistant to Imipenem;  The most common uropathogen was Escherichia coli.

Competing interests
The authors declare no competing interest.

Authors' contributions
Adelaide Ayoyi conceived the study, drafted the proposal, carried out data collection, laboratory examination, data analysis,

Acknowledgments
The authors wish to acknowledge the all attending Nurses and laboratory scientists from the participating health centers for the role in evaluation of subjects and collection of samples. The urine microscopy was done at clinics and was done by laboratory scientists. This study was funded by National Commission for Science Technology and Innovation. Table 1: Prevalence of asymptomatic bacteriuria