Aim: Urinary tract infection (UTI) is a term applied to a variety of clinical conditions ranging from asymptomatic presence of bacteria in urine to severe infection of kidney with resultant sepsis. Despite the widespread availability of antibiotics it remains the most common bacterial infection in human beings. The aim of this study was to analyze the bacteriological spectrum of UTI and its antibiogram among patients admitted at Rawalpindi Institute of Cardiology (RIC).

Material and methods: Urine specimens were taken from patients of all age groups admitted in Rawalpindi Institute of Cardiology from January to December 2018. A total of 727 urine specimens were cultured on Cysteine Lactose Electrolyte Deficient Agar. The growth was identified and antibiotic susceptibility was carried out by disc diffusion method as per recommended CLSI guidelines.

Results: Out of 727 urine specimens, 291 were culture positive. Escherichia coli was the most frequent uropathogen (38%) followed by Klebsiella pneumonia (14.8%), Enterobacter spp. (11%) and Enterococcus spp. (8.2%).

Discussion: Urinary tract infection is common among hospitalized patients. Frequent use of antibiotics has led to antibiotic resistance against common infections including UTI. However, very little information is available about UTIs in patients with ischemic heart disease and other cardiac ailments. Our study has also confirmed UTI being frequent among hospitalized cardiac patients. Nitrofurantoin was the most effective antibiotic followed by Imipenem, Meropenem and Amikacin against Enterobacteriacae. Most isolates showed resistance to Ciprofloxacin and Ampicillin.

Keywords: Urinary tract infection, Escherichia coli, Antibiotics

INTRODUCTION

UTI is associated with significant mortality and morbidity. About 150 million people develop urinary tract infection every year [1]. UTI is more common in women than in men due to the short length of urethra [2].

All specimens were inoculated on Cysteine Lactose Electrolyte Deficient (CLED) Agar and incubated at 37°C for 24 h. Twenty or more colonies on CLED Agar were taken as significant. Antibiotic susceptibility was carried out by disc diffusion method against Ampicillin, Amoxicillin/Clavulanate, Trimethoprim/Sulphamethaxazole, Fosfomycin, Amikacin, Gentamicin, Aztreonam, Nitrofurantoin, Ciprofloxacin, Ceftriaxone, Cefotaxime, Pipracillin/Tazobactam, Imipenem, Meropenem as recommended in CLSI-M 100 S 26^th edition [6].

RESULTS

Out of 727 urine samples, 327 (45%) were obtained from females and 400 (55%) from males patients. Among all urine samples 291 (40%) were culture positive whereas 436 (60%) were culture negative. Among all positive cultures 150 (51.5%) were from male patients whereas 141 cases (48.5%) were from females patients.

The frequency of various organisms isolated in urine specimens is shown in Table 1. Escherichia coli were the most frequent urinary pathogen followed by Klebsiella spp. and others. E. coli was susceptible to Nitrofurantoin (76%) followed by Imipenem (67%) and Meropenem (62%). It was least susceptible to Ampicillin (4.5%), Ciprofloxacin (22%) and Cefotaxime (30%). Ciprofloxacin was seen least effective against all Enterobacteriacae whereas Nitrofurantoin, Imipenem and Meropenem were found the most effective as per their susceptibility (Table 2). 

DISCUSSION

Effective management of UTI depends upon the identification of microorganism and its susceptibility. It often requires close cooperation between clinician and microbiologist [7].

UTI is the most common bacterial infection and second common cause of morbidity and mortality in all age groups. In a study from Pakistan Institute of Medical Science, out of 1363 urine samples 289 were found positive for UTI [8]. Similar findings were observed in a study from Agha Khan University Hospital, Pakistan, where out of 9892 urine samples 37% were culture positive [9]. In that study, the frequency of UTI in females and males was 60.5% and 39.5%, respectively. However, in our study the gender distribution is 51.5% in males and 48.5% in females out of total 291 culture positive cases. The frequency of uropathogens isolated in our study is different from other studies where UTI was more frequent in females than in males. The clinical factors including anatomic differences, hormonal effects and behavioral patterns contribute to frequent UTI [10,11]. Hasan et al. [12] have reported a prevalence rate of UTI in females (70.5%) and males (29.5%). However, in our study being carried out in a cardiac hospital, UTI is more frequent in males than in females since myocardial ischemia is more common in male population than females.

Escherichia coli is the predominant urinary pathogen (38%) followed by Klebsiella pneumonia (K. pneumonia) (14.8%) in our study. Our results are similar to that were reported by Patel et al. [13] in Jamnagar, Gujrat and of Savitha et al. [14], India who had also found E. coli and K. pneumoniae as the most common uropathogen. They found E. coli causing UTI in 53.38% and 48.04% and Klebsiella spp. in 18.98% and 8.82% of the isolates respectively [15]. Yadav et al. [16] have reported E. coli (61%), followed by S. aureus (12%), CONS (7%), Enterococcus (5%), K. pneumoniae (5%), Candida spp. (3%), Proteus spp. (2%) and others (6%). The most effective antibiotics in our study are Nitrofurantoin, Imipenem, Meropenem and Amikacin against Enterobacteriaceae. Similar findings have been reported by Niranjan et al. in Puducherry, India [15]. However, Yadav et al. [16] have found Imipenem as the most effective antibiotic against E. coli 85.9% and against Klebsiella spp. 89.4%.

In a study from Ethiopia out of 1404 urine samples, 319 (22.7%) were culture positive. Escherichia coli (63.6%) were the predominant uropathogen. Resistance to Erythromycin, Amoxicillin and Tetracycline was quite high in that study [17].

Nitrofurantoin is found as the most effective to treat UTI in our study. Similar findings were observed in surveillance studies by Sasirekha [18] and Khameneh and Afshar [19] other Indian studies.

Most of the organisms showed resistance to Ampicillin and Ciprofloxacin in our study. It could be attributed to empirical use of these antibiotics to treat common infections including pneumonias in ischemic patients beside preoperative and postoperative prophylactic use of these antibiotics in our hospital. Similar findings have been observed by Nozarian and Abdollahi [20] and Keah et al. [21]. Resistance to Ampicilin (50.1%) and Cotrimoxazole (22.1%) was observed in patients with complicated UTI and acute pyelonephritis in a study from United States [22].

In our study E. coli is susceptible to Nitrofurantoin (76%) followed by Imipenem (67%) and Meropenem (62%). It is least susceptible to Ampicillin (4.5%), Ciprofloxacin (22%) and Cefotaxime (30%). Ciprofloxacin is seen the least effective against all Enterobacteriacae whereas Nitrofurantoin, Imipenem and Meropenem are found the most effective as per their susceptibility (Table 2).

Klebsiella spp. is the second most frequently isolated uropathogen (14.8%). It is most susceptible to Nitrofurantoin (76%), Imipenem (70%) and Meropenem (65%). Amikacin is more effective than Gentamycin being 63% % and 56%, respectively. Similar findings have been reported by Patel et al. [13] and Agha Khan University Hospital [9].

We have found Enterobacter spp. 11% in our culture isolates whereas it was reported 5% from Agha Khan University hospital, Karachi Pakistan and 8% by Farooq et al. [9] Nozarian and Abdollahi et al. [20]. The later had reported sensitivity of Enterobacter spp. 82.3% and 86.7% to Nitrofurantoin and Amikacin, respectively, whereas it is 94% and 75%, respectively in our study. Susceptibility towards Imipenem is 72% and Meropenem is 63%. The least susceptibility is observed against Ampicillin, Ciprofloxacin and Cephalosporins in that order. All isolates of Serratia spp. are susceptible to Gentamycin, Trimethoprim/Sulphamethoxazole and Nitrofurantoin (100%).

The frequency of S. aureus and CONS in our study is 6.2% and 3.4%, respectively (Table 2), whereas Yadav et al. [16] have reported these as 12% and 7%, respectively. MRSA and Methicillin-resistant Coagulase Negative Staphylococcus (MR CONS) are 11% and 10%, respectively in our study. While, Yadav et al. [16] have reported these as 33% and 96%, respectively. All of our Staphylococcal isolates are susceptible to Linezolid, Vancomycin and Nitrofurantoin whereas Yadav et al. [16] have reported these as 95.2%, 100% and 87.4%, respectively [16].

Enterococcus was found in 8% of the isolates whereas Yadav et al. [16] have reported it as 6% in their study. We have found it 93% susceptible against Linezolid and 83% against Vancomycin and Nitrofurantoin each.

CONCLUSION

UTI is the most common disease among hospitalized patients around the world. Our study has also confirmed that UTI is also common in patients admitted in a cardiac hospital. UTI is more frequent in males than in female patients admitted in our cardiac hospital. Escherichia coli were the most frequent uropathogen. Most of the isolates were susceptible to Nitrofurantoin, Imipenem, Meropenem and Amikacin but resistant to Amoxicillin, Ciprofloxacin and Ceftriaxone.

1.       Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ (2015) Urinary tract infections: Epidemiology, mechanisms of infection and treatment options. Nat Rev Microbiol 13: 269-284.

2.       Al-Achi A (2008) An introduction to botanical medicines: History, science, uses and dangers. Westport, Conn.: Praeger Publishers, p: 126.

3.       https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-infection-pyelonephritis

4.       https://www.niddk.nih.gov/health-information/urologic-diseases/bladder-infection-uti-in-adults

5.       Woodford HJ, George J (2011) Diagnosis and management of urinary infections in older people (PDF). Clin Med 11: 80-83.

6.       Richard T, Patel JB (2013) Performance standards for antimicrobial. 26^th Edn.

7.       Water G, Harrison B, Kunin G (1996) Urinary tract infection. N Engl Med J, pp: 248-250.

8.       Amber M, Shoaib M, Rehman A, Zafar MM, Ain QT, et al. (2016) Comparative study of causative agents of UTI among indoor, outdoor, children and adult patients of Pakistani population. Bull Env Pharmacol Life Sci 58: 34-41.

9.       Farooqui B, Alam M, Khurshid M (1989) Urinary tract infection. J Pak Med Assoc 39: 129-131.

10.    Miller O, Hemphill RR (2001) Urinary tract infection and pyelonephritis. Emerg Med Clin North Am 19: 655-674.

11.    Foxman B (2002) Epidemiology of urinary tract infections: Incidence, morbidity and economic costs. Am J Med 113: 5-13.

12.    Hasan AS, Nair D, Kaur J, Baweja G, Deb M, et al. (2007) Resistance patterns of urinary isolates in a tertiary Indian hospital. J Ayub Med Coll Abbottabad 19: 39-41.

13.    Patel S, Taviad PP, Sinha M, Javadekar TB, Chaudhari VP (2012) Urinary tract infections (UTI) among patients at GG Hospital and Medical College, Jamnagar. Nat J Comm Med 3: 138-141.

14.    Savitha T, Murugan K, Thangamariappan K (2011) Prevalence study on emergence of urinary tract infection in Erode, Tamil Nadu, India. Int J Curr Res 2: 5-13.

15.    Niranjan V, Malini A (2014) Antimicrobial resistance pattern in Escherichia coli causing urinary tract infection among inpatients. Indian J Med Res 139: 945.

16.    Yadav M, Pal R, Damrolien S, Khumanthem SD (2017) Microbial spectrum of urinary tract infections and its antibiogram in a tertiary care hospital. Int J Res Med Sci 5: 2718-2722.

17.    Kibret M, Abera B (2014) Prevalence and antibiogram of bacterial isolates from urinary tract infections at Dessie Health Research Laboratory, Ethopia. Asian Pac J Trop Biomed 4: 164-168.

18.    Sasirekha B (2013) Prevalence of ESBL, AmpC β-lactamases and MRSA among uropathogens and its antibiogram. EXCLI J 12: 81-88.

19.    Khameneh ZR, Afshar AT (2009) Antimicrobial susceptibility pattern of urinary tract pathogens. Saudi J Kidney Dis Transplant 20: 251.

20.    Nozarian Z, Abdollahi A (2015) Microbial etiology and antimicrobial susceptibility of bacteria implicated in urinary tract infection in Tehran, Iran. Iran J Pathol 10: 54.

21.    Keah SH, Wee EC, Chng KS, Keah KC (2007) Antimicrobial susceptibility of community-acquired uropathogens in general practice. Malays Fam Phisician 2: 64-69.

22.    Peterson J, Kaul S, Khashab M, Fisher A, Kahn JB (2007) Identification and pre-therapy susceptibility of pathogens in patients with complicated urinary tract infection or acute pyelonephritis enrolled in a clinical study in the United States from November 2004 through April 2006. Clin Ther 29: 2215-2221.