IJCRR

IJCRR - 8(15), August, 2016

Pages: 33-38

Date of Publication: 11-Aug-2016

ANTIMICROBIAL RESISTANCE DEMONSTRATED BY UROPATHOGENIC ESCHERICHIA COLI AT A TERTIARY CARE HOSPITAL

Author: Snehal S. Anturlikar, Niyati A. Trivedi

Category: Healthcare

Abstract:Background: Urinary tract infection (UTI) is one of the most common bacterial infections encountered by clinicians in developing countries. Escherichia coli is the most common causative organism of UTI. Development of resistance by E.coli towards different antimicrobial agents is alarming. Hence, our study was planned to analyze the antimicrobial resistance pattern of E.coli isolates at a tertiary care teaching hospital.
Materials and method: Culture sensitivity reports of all urine samples sent to microbiology department of a tertiary care teaching hospital during the period of July 2010-June 2013 were screened. Detailed reports were collected for all the samples in which E.coli was identified as a causative organism. Culture sensitivity testing was done by modified Kirby-Bauer disk diffusion (high media) method.
Result: E.coli was isolated in total 1155 urine samples during the period of three years. Majority of patients belonged to pediatric age group (823/1155, 71.25%). 52.21% samples were of female patients. Thirty-one antimicrobial agents were tested for 13048 times for their sensitivity towards E.coli. Antimicrobial resistance ranging from 14.58% to 100% was noted among various antimicrobials. E.coli showed 38.23% resistance towards aminoglycosides, 52.27% resistance towards quinolones, 54.95% resistance towards beta-lactams and 67.33% resistance towards miscellaneous group of antimicrobials.
Conclusion: Proper selection and wise use of available antibiotics will help in reducing the rate of increase in resistance. Periodic monitoring of antimicrobial susceptibility pattern of causative agent in a particular setting will be helpful in guiding judicious use of antimicrobial agents limiting the spread of resistant strains.

Keywords: Aminoglycosides, Antimicrobial susceptibility, Escherichia coli, Urinary tract infection.

Full Text:

INTRODUCTION
Urinary tract infections (UTI) is one of the most common bacterial infections encountered by clinicians in developing countries[1] and constitute a great proportion of prescription of antibiotics [2]. It has been estimated that symptomatic urinary tract infections (UTI) occurs in as many as 7 million visits to emergency units and 100,000 hospitalizations annually. UTI has become the most common hospital-acquired infection, accounting for as many as 35% of nosocomial infections, and it is the second most common cause of bacteraemia in hospitalized patients [3]. Escherichia coli is the most common causative organism of urinary tract infections.[4] The emergence of drug resistance to trimethoprim-sulfamethoxazole, the penicillins, cephalosporins, and fluoroquinolones by Uropathogenic Escherichia coli (UPEC) has limited the options for selecting the appropriate antibiotic for the treatment of urinary tract infections [4]. As resistance to commonly prescribed antimicrobial agents is increasing significantly, there is a need of periodic analysis of the pattern and sensitivity of organisms isolated and the results need to be communicated to doctors [5]. Hence, this study was carried out with an aim to analyze the antimicrobial resistance pattern of E.coli towards commonly prescribed antimicrobial agents.

MATERIALS AND METHODS
Culture sensitivity reports of all urine samples sent to microbiology department of a tertiary care teaching hospital during the period of July 2010-June 2013 were screened. Detailed clinic- epidemiological data were collected for all the samples in which E.coli was identified as a causative organism and the data was entered into Microsoft excel spreadsheet 2007. Antimicrobial susceptibility testing was done by modified Kirby Bauer disc diffusion method [6]. Statistical analysis Data has been presented as percentage of resistance or Mean (SD). Chi square test was performed as a test of significance whenever necessary using GraphPad InStat software version 3.10 (trial version). P value < 0.05 was considered statistically significant. RESULTS Amongst 33,000 samples of positive urine culture received at the Microbiology Department in a tertiary care teaching hospital during the period of 3 years (July 2010- June 2013), E.coli isolates were obtained from 1155 urine samples. Out of 1155 urine samples, 603 samples (52.21%) were of female patients while 552 samples (47.79%) were of male patients. The age of the patients ranged from 1 day to 87 years with mean age of 16.33± 20.05 years. Maximum numbers of samples (823/1155, 71.25%) were obtained from pediatric age group followed by patients belonging to adult age group (270/1155, 23.38%). Only 62 (5.37%) samples belonged to the patients of geriatric age group. E.coli isolates were tested for their susceptibility towards 31 different antimicrobial agents with each E.coli isolate being tested for its susceptibility towards 5 to 17 different antimicrobial agents (Mean 11± 3.89), out of which it showed resistance towards at least 0 to 10 antimicrobials (Mean 5± 3.32). Out of total 13,048 times for which different antimicrobials were tested for their susceptibility towards E.coli, 6824 (52.30%) times resistance was observed while 6188 (47.42%) times sensitivity was observed and for 36 times (0.28%) intermediate sensitivity was observed. Group wise resistance pattern of E.coli isolates. E.coli isolates were tested for their susceptibility towards four different groups of antimicrobial agents including aminoglycosides, quinolones, beta lactams and miscellaneous (which includes nitrofurantoin, doxycycline, tetracycline etc.). Aminoglycosides were tested for 3071 times for their susceptibility towards E.coli out of which resistance was shown towards them for 1174 times (38.23%). (Table1) Among the four different aminoglycosides tested, amikacin was the most commonly tested antimicrobial agent (1084/1155, 93.85%) followed by gentamicin (950/1155, 82.25%). Percentage of resistance amongst aminoglycosides ranged from 77.45% to 27.21% with amikacin sowing least resistance. Total seven quinolones were tested for 3046 times for their susceptibility towards E.coli out of which resistance was observed for 1592 times (52.27%). (Table2) Marked difference in resistance was observed among quinolones with lomefloxacin and levofloxacin exhibiting 100% resistance while gatifloxacin showed 14.58% resistance towards E.coli. Total 14 beta-lactams were tested for total 4719 times for their susceptibility towards E.coli out of which resistance was observed for 2593 (54.95%) times. (Table3)

Amongst beta-lactams, piperacillin (1073/1155, 92.90 %) was the most commonly tested antimicrobial agent while ceftriaxone showed highest resistance (100%, 5/5) towards E.coli. Out of 1249 times for which 3rd generation cephalosporins were tested, 841 times (67.33%) resistance was observed towards them. 86.96% resistance (20/23) was observed towards 4th generation cephalosporin. Among the six miscellaneous antimicrobials tested for their susceptibility towards E.coli for 2176 times, resistance was observed for 1465 times (67.33 %). Chloramphenicol (987/1155, 85.45%) was most commonly tested antimicrobial agent as shown in table 4. Highest resistance was observed towards doxycycline (100%, 4/4) followed by cotrimoxazole (76.71%, 56/73). Out of 1155 samples where E.coli was isolated, 925 (80.1%) samples showed resistance to atleast one agent from three or more antimicrobial families and hence was identified as MDR. The pattern of resistance among samples obtained from male and female patients appeared similar for all the antimicrobial agents tested, except for nitrofurantoin. In case of nitrofurantoin higher resistance (p=0.025) was observed among male patients (69.94%, 328/469) as compared to samples obtained from female patients (63.12%, 315/499). Except for amikacin (p=0.013), piperacillin (p<0.0001) and combination of piperacillin and tazobactam (p=0.01) which showed significant increase in percentage of resistance from the year July 2010 to June 2013, overall percentage of resist- ance remained similar for rest of the antimicrobials over the period of three years.

DISCUSSION
Urinary tract infections (UTI), being the most common infections diagnosed in community and hospital, are to be treated scrupulously considering the type of infecting organism and its antibiotic resistance pattern [7]. The prevalence of antimicrobial resistance in urinary pathogens is increasing worldwide.[8] The consequences of resistance are severe as infection caused by resistant microbes fail to respond to standard treatment, resulting in prolonged illness and greater risk of death [9]. Escherichia coli is the most common causative organism of urinary tract infections.[4] According to a WHO report, E.coli has acquired resistance to many different groups of antimicrobials [10], and the prevalence of antimicrobial resistance varies greatly between and within countries and between different pathogens.[11] Treatment of UTI cases is often started empirically and therapy is based on information determined from the antimicrobial resistance pattern of the urinary pathogens [8]. Accurate bacteriologic records of culture results may provide guidance on empirical therapy before sensitivity patterns are available [8]. Hence, keeping this in mind, our study was planned to analyze the antimicrobial resistance pattern of E.coli isolates towards commonly prescribed antimicrobial agents in a tertiary care hospital. 1155 urine samples where E.coli was isolated as a causative organism were collected during the period of 3 years (July 2010- June 2013) from different clinical departments of the hospital. Total 31 antimicrobial agents were tested for their susceptibility towards E.coli using disc diffusion method (Hi Media). Majority of the samples were of female patients (603/1155, 52.21%) while 552 samples (47.79%) were of male patients. This data was similar to a study conducted by Abdul Rahaman Shariff V A et al.[4] , Shamataj Razak et al.[8] and Patel S et al.[3] where majority of urine samples were obtained from female patients. In our study, percentage of resistance ranged from 38.23% towards aminoglycosides to 67.33% towards miscellaneous group of antimicrobial agents. Resistance observed towards amikacin, gentamicin and norfloxacin was 27.21% (295/1084), 40.53% (385/950) and 68.68% (658/958) respectively. A comparable finding with our study for resistance towards amikacin was demonstrated by Shamataj R et al.[8] where resistance observed was 30.12%, while resistance demonstrated towards gentamicin and norfloxacin was 73.5% and 93.98% which was not in accordance to our study. However, the sample size was smaller (i.e. 156) than our study. In our study, E.coli showed 100% resistance towards levofloxacin (tested for lesser number (i.e. 9) of times), while contrast results were obtained in a study conducted by Patel S et al [3]. Among the beta lactams tested for their susceptibility towards E.coli, 51.54% (553/1073) and 70.65% (657/930) resistance was observed towards piperacillin and combination of ampicillin and sulbactam respectively. On the contrary, resistance observed towards piperacillin and combination of ampicillin and sulbactam was 74.9% (968/1292) and 37.7% (487/1292) respectively, in a study conducted by Abdul Rahaman Shariff V A et al.[4] Another study conducted by Patel S et al. [3] showed 24% resistance towards combination of ampicillin and sulbactam which was in contrast to our study.

Resistance observed towards nitrofurantoin was 66.43% (643/968) in our study, while in a study conducted by Shamataj R et al.[8] and Patel S et al.[3], E.coli showed lesser resistance (18.08% and 20% respectively) towards nitrofurantoin. However, sample size was smaller in case of study conducted by Shamataj R et al. (i.e.156) than our study. A study conducted by Abdul Rahman Shariff V A et al. [4] reported 0% (0/2584) resistance of E.coli towards carbapenems, while in our study resistance observed towards carbapenem group of antimicrobials was 33.58% (90/268) but carbapenems were tested for lesser number of times (i.e. 268 times) in our study. In our setting the resistance observed towards cotrimoxazole, 3rd generation cephalosporins and fluoroquinolones was worrisome. Antimicrobial agents were viewed as miracle cures when first introduced into clinical practice. However, it became evident rather soon after the discovery of penicillin that resistance developed quickly, terminating the miracle. This serious development is ever present with each new antimicrobial agent and threatens the end of the antimicrobial era. Today every major class of antimicrobial is associated with the emergence of significant resistance [12]. Proper selection of antimicrobial agent is the most crucial step in successful management of urine infection. This data provides useful information not only for clinicians in determining the appropriate antimicrobial regimen [13] but also for microbiologists to procure appropriate antimicrobial suscep-tibility discs. That will lead to judicious use of antimicrobials and providing of effective antimicrobial therapy which will help in limiting the emergence of drug resistance and spreading of multidrug resistant strains. Limitations of the study were: (1) As this was an in vitro study hence results cannot be directly applied to clinical setting as multiple factors play a role in actual response of the antimicrobial agent. (2) The study period (i.e. three years) was not longer enough to analyze the trend in antimicrobial resistance pattern of E.coli towards different antimicrobial agents tested. (3) As 90% of the isolates were obtained from in-patient department, comparison could not be done with isolates obtained from out-patient department.

CONCLUSION
In our setting, overall there was high prevalence of resistance of E.coli isolates towards various groups of antimicrobial agents. Hence, periodic monitoring of antimicrobial susceptibility pattern of causative agent in a particular setting will be helpful in guiding judicious use of antimicrobial agents and limiting the spread of resistant strains.

ACKNOWLEDGEMENT
Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed. Source of funding: none Conflict of interest: none

References:

1. Getenet B, Wondewosen T. Bacterial Uropathogens in Urinary Tract Infection and Antibiotic Susceptibility Pattern in Jimma University Specialized Hospital, Southwest Ethiopia. Ethiop J Health Sci 2011;21:141-46.

2. Khameneh ZR, Afshar AT. Antimicrobial Susceptibility Pattern of Urinary Tract Pathogens. Saudi J Kidney Dis Transpl 2009;20:251-53.

3. Patel S, Taviad PP, Sinha M, Javadekar TB, Chaudhari VP. Urinary Tract Infections Among Patients at G.G. Hospital and Medical College, Jamnagar. Natl J Community Med 2012;3:138- 141.

4. Shariff V A AR, Shenoy MS, Yadav T, Radhakrishna M. The Antibiotic Susceptibility Patterns of Uropathogenic Escherichia coli, with Special Reference to the Fluoroquinolones. J Clin Diagn Res 2013;7:1027-30.

5. Tiwari P, Kaur S. Profile and Sensitivity Pattern of Bacteria Isolated from Various Cultures in a Tertiary Care Hospital in Delhi. Indian J Public Health 2010;54:213-15.

6. Bauer AW, Kirby WMM, Sherris JC, Turck M, et al. Antibiotic susceptibility testing by a standardized single disk method. Am J Clin Pathol 1966;45:493-96.

7. Rani H, Kaistha N. Choice of Antibiotics in Community Acquired UTI due to Escherichia coli in Adult Age Group. J Clin Diagn Res 2011;5:483-85.

8. Razak SK, Gurushantappa V. Bacteriology of Urinary Tract Infection and Antibiotic Susceptibility Pattern in a Tertiary Care Hospital in South India. Int J Med Sci Public Health 2012;1:109- 12.

9. World Health Organization. Regional Strategy on Prevention and Containment of Antimicrobial Resistance 2010-2015; 2010.

10. Holloway K, Mathai E, Sorensen TL, Gray A. CommunityBased Surveillance of Antimicrobial Use and Resistance in Resource-Constrained Settings. Report on five pilot projects. Geneva: World Health Organization 2009.

11. Vila J, Pal T. Update on Antibacterial Resistance in Low-Income Countries: Factors Favoring the Emergence of Resistance. The Open Infectious Diseases Journal 2010;4:38-54.

12. Tawanda G. General Principles of Antimicrobial Therapy. In: Brunton L, editor. Goodman and Gilman’s The Pharmacological Basis of Theraupeutics. 12th ed. The McGraw-Hill Companies, Inc., 2011.p. 1375-76.

13. Yilmaz N, Agus N, Yurtsever SG, Pullukcu H, Gulay Z, Coskuner A, et al. Prevalence and antimicrobial susceptibility of Escherichia coli in outpatient urinary isolates in Izmir, Turkey. Med Sci Monit 2009;15:61-65.