Journal of Bacteriology & Parasitology

Urinary tract infection (UTI) is a common bacterial infection in mankind and is a major public health problem in terms of morbidity and financial cost which affecting 150 million people each year worldwide [1,2]. In 2007, in the United States alone, there were an estimated 10.5 million office visits for UTI symptoms [3].

Diagnosis and treatment of UTI are empirical mostly because this is imperative to start antibiotics in almost all cases due to low socio economic status, urinary obstruction, unavailability of urine culture facilities for rural patients in Bangladesh. To initiate empirical treatment with appropriate antibiotic is necessary to have current knowledge regarding causative organisms and their antibiotic sensitivity pattern [4]. But alarming fact is that a large number of patient do not respond to conventional antimicrobial agents [5].

Antimicrobial resistance is a well-known important emerging clinical and public health problem. There are various reports available in last two decades about changing pattern of pathogen and their sensitivity pattern to routinely used antibiotics which makes the situation miserable [5], increasing antibiotic resistance among uropathogens to commonly prescribed drugs has become a global reality. Resistance occurs in intestinal bacteria due to antibiotic therapy for treating infections outside the urinary tract [6]. The irrational use of antibiotics has an influence in the spread of antimicrobial resistance among bacteria [7,8]. Controlling antimicrobial resistance is a major issue confronting organized health care today. Therefore this is warranted to know information about rapidly changing sensitivity pattern of micro-organisms towards antibiotics in UTI. To get update information for proper therapeutic interventions, periodic evaluation and regional surveillance programs is necessary for the development local data about the antimicrobial sensitivity to uropathogens for in UTI.

The present study was undertaken to observe the current bacterial uropathogens and their antibiotic sensitivity pattern in a tertiary hospital in Bangladesh to compare previous same pattern of study in 2011 [9]. It will be helpful for awareness and antibiotic use in UTI in this tertiary level hospital and country level.

It was a prospective study in department of medicine Comilla medical college hospital during the period of July 2015-June 2016. All the patients included in this study ware above 12 years of age, presented with the suspected UTI (dysuria, frequency, fever and pain in lower abdomen). The patients presented with active menstruation, PID, tubo-ovarian disease, appendicitis, colitis, epididymitis and orchitis diagnosed either clinically or by investigations were excluded from this study. Those patients were on antibiotic advised to stop drug for 48 h and were included in this study.

Freshly voided midstream clean-catch urine samples were collected from each 658 patients of different age and sex groups in a sterile screw capped universal container. The specimen was labeled and transported to the microbiology laboratory for processing and cultured within half an hour of collection. A modified semi-quantitative technique using a standard calibrated bacteriological loop of urine was performed to transfer 0.001 ml of sample on blood agar and MacConkey agar media. After allowing the urine to be absorbed into the agar, the plates were then inverted and incubated aerobically at 37°C for 24 h. The plates were then examined macroscopically for bacterial growth. The colony count was done using semi quantitative method. Number of colonies obtained was multiplied by 1000 to obtain the colony forming units (CFU)/ml [10].

A significant growth is considered if the number of colony is ≥ 10⁵ CFU/ml. Colonial appearance and morphological characters of isolated bacteria was noted and gram staining was done for identification of the isolated organisms. The characteristic bacteria on the culture media were aseptically isolated.

Antimicrobial sensitivity tests were carried out by disc diffusion technique using Muller Hinton Agar. Interpretation of results was expressed in sensitive and resistant depending upon the size of the zone of inhibition. The antibiotics used for susceptibility testing in our study were amoxycillin, amoxyclav, cefotaxime, ceftriaxone, cephalexin, nalidexic acid, nitrofurantoin, mecillinum, amikacin, cefixime, ceftazidime cefuroxime, cephradine ciprofloxacin cotrimoxazole, gentamycin, tazobactum, meropenem, and imipenem.

A total of 658 urine samples were collected from suspected UTI patients.

Base line characteristics in patients in urine culture without growth and with growth had shown in Tables 1 and 2.

Table 1: Base line characteristics in patients without growth in urine culture.

Table 2: Base line characteristics in patients with growth in urine culture.

Among 198 culture positive samples, E. coli was ranked highest 171 (86%). Growth of Klebsiella pneumonia and Enterococcus was found in 17 (9.6%) and 10 (5%) samples respectively. It was also observed from this table that the maximum numbers of isolates were distributed among the females 123 (62%) (Table 3).

Table 3: Frequency of Isolation of organism in relation to sex of patient and their overall percentage.

Study shows, meropenem, imipenem, amikacin, tazobactum, gentamycin nitrofurantoin, and mecillinum, were found to be most effective antibiotic against most of the uropathogens. In vitro sensitivity of the isolates to these antibiotics was shown to be varied from 88% to 100%. This table also shows high degree of resistance against commonly used antibiotics-amoxycillin, amoxiclav, cephradine and cefixime Tables 4 and 5. In vitro resistance of the isolates to these antibiotics was varied from 60% to 86%.

Table 4: Comparative study between the common isolated uropathogenic bacteria in the year 2016 and 2011. UTI with E. coli was found statistically significant increase in the year 2016 with p values <0.01.

Table 5: In vitro antibiotics sensitivity pattern of the bacteria (n=198).

There was statistically significant reduction in sensitivity pattern in year 2016 in comparison to 2011 was detected for imipenum, ceftriaxone, and amoxiclav. On the other hand significant increase in sensitivity pattern was found for nalidexic acid, ciprofloxacin, mecillinum, colistin and cotrimoxazole. No statistically significant change in sensitivity pattern was shown for other antibiotics (Table 6).

Table 6: Comparative study between 2016 and 2011 of trend of antibiotic sensitivity pattern of uropathogenic bacteria.

This study demonstrates the distribution and antibiotic susceptibility pattern of bacteria isolated from patients with suspected UTI from a tertiary care center. The patients attending in our center with symptoms suggestive of UTI, 31% had culture positive, which was nearer to our previous study in 2011 where growth was 24% [9]. Studies by BHN Yasmeen et al. [11] on 2014 in Bangladesh shows 21% urine sample were positive for pathogenic organisms. Our study showed a high prevalence of UTI in females (73.57%) than in males (35.14%) which is similar to other reports where it was shown that the frequency of UTI is greater in females as compared to males [12-14]. It has been extensively reported that adult women have a higher prevalence of UTI than men, principally owing to anatomical and physical factors [15-17].

In this study, the most predominant isolated organism was E. coli (86%) which was significantly higher (p value was <0.01) than our previous studies in 2011 where E. coli was 75% [9].

In this study the most powerful antibiotic was meropenem, imipenem, tazobactum and amikacin. These antibiotics show their efficacy against 99-100% of the uropathogens which was similar to our previous study on 2011 [9]. Uropathogens shows higher degree of resistance against most of the antibiotics used for sensitivity. This increasing resistance is due to irrational consumption of most of the antibiotics during the past decade in our region [8,18,19]. As meropenem imipenem and tazobactum are highly expensive medicine which makes it very difficult to purchase by most of the peoples of our community. So like our previous study still our recommendation is in favor of using amikacin regarding empirical antibiotics in UTI. The most sensitive oral antibiotics were nitrofurantoin. It shoes its effectiveness against 88% of the isolates. This drug exhibited low resistance rate in the major part of the world (0–5.4%), despite of its use for many years which was because of localized action of this drug only on the urinary tract [20]. So, nitrofurantoin can be considered as first line, cost saving and effective oral therapy in UTI. There was significant reduction in sensitivity pattern in year 2016 was detected for imipenum, ceftriaxone, and amoxiclav, possibly because random use of these antibiotics in past few years with inadequate dose and duration. Uropathogens resistance to antibiotic has now become a public health concern in Bangladesh [21]. There was significant increase in sensitivity pattern in year 2016 was detected for Nalidexic acid, Mecillinum and Colistin because these antibiotics are not commonly used in our community in last few years. According to guideline by Infectious Diseases Society of America (IDSA) in the year 2011, an antibiotic is no longer recommended for empirical treatment of acute UTI if there is >20% resistance prevalence to that particular antibiotic [22]. According to this guideline of IDSA, most of the antibiotics used in our study should not be used for empirical treatment of acute UTI and our standard treatment guidelines for UTI is not sufficient which requires a large scale study.

There is urgent need of constant monitoring with culture and sensitivity pattern of specific pathogens in different health care centre’s in our country. Community awareness program should be undertaken for adherence to treatment protocol considering bacterial resistance and emerging multidrug resistant strains. It is necessary to conduct a regional research on the culture and sensitivity patterns of the bacteria. All the authors contributed equally in this study.

UTI with E. coli was significantly increased in the year 2016. This study failed to show a steady increase in resistance to all studied antibiotics. Imipenem, meropenem, tazobactum, amikacin and nitrofurantoin still remain more sensitive in this comparative study. Comparative study of 2016 vs. 2011 shows significant increasing resistance for imipenum, ceftriaxone, amoxiclav and increasing sensitivity for nalidexic acid, ciprofloxacin, mecillinum, colistin, cotrimoxazole.