Department of Microbiology, Government Medical College, Sir Takhtasinhji Hospital, Bhavnagar, Gujarat, India-364001
Abstract
Background and objectives: Urinary tract infections remain one of the most common infections in the community and susceptibility of uropathogens to commonly used antimicrobials has declined over the years. It is important to periodically study the antibiogram of uropathogens, so that empiric treatment can be determined using recent data and thus improving patient outcomes. The present study evaluated the antibiotic resistance trend of prevalent Gram-negative uropathogens in urine samples received at the microbiology laboratory at a tertiary care hospital.
Material and methods: The study was conducted at the Department of Microbiology, Sir Takhtsinhji Hospital, Bhavnagar for one year period from March 2021 to February 2022. All received urine samples for culture and sensitivity were included in the study. All samples were subjected to culture and sensitivity using standard methods.
Results: During study period, 918 (18.6%) organisms were isolated from 4938 urine samples. Out of 918, 85.1% (781) was Gram-negative and 9.8% was Gram-positive bacteria while 5.1% was Candida spp. Escherichia coli was the most prevalent (61.7%) of the total Gram-negative isolates. Gram-negative isolates were most resistant to amoxicillin/clavulanic acid, quinolones, trimethoprim/sulfamethoxazole. The rate of resistance to aminoglycosides, nitrofurantoin, third generation cephalosporins and carbapenems was comparatively low.
Conclusion: Antimicrobial resistance of the prevalent uropathogens should be monitored routinely to plan effective empirical therapy.
July 2024; Vol. 18(2):007. DOI: https://doi.org/10.55010/imcjms.18.019
*Correspondence:Kairavi Desai, Department of Microbiology, Government Medical College, Sir Takhtasinhji Hospital, Bhavnagar, Gujarat, India-364001. E-mail:[email protected]
Introduction
Urinary tract infection (UTI) is a common bacterial infection encountered in the community and hospitals. UTI accounts for 35% of total hospital acquired infections (HAIs). It is a leading cause of morbidity and healthcare expenditures in people of all ages [1]. Predisposing factors for UTI are age, gender, race, nutrition, hygiene, and immune status of the patients [2]. Post-menopausal women have a higher incidence of UTI due to uterine prolapse, less estrogen activity, altered vaginal microbiota, and associated co-morbid conditions like diabetes mellitus [3,4]. Prolonged hospital stay due to other medical and surgical problems and urinary catheterization are the most important risk factors among older people of both sexes.
It is important to know the trends of antimicrobial susceptibility patterns of bacteria causing UTI at a given locality or hospital to ensure effective treatment. First and second generation cephalosporins, nitrofurantoin and fluoroquinolones are the most effective drugs for community acquired UTIs. On the other hand, parenteral therapy with third generation cephalosporins and carbapenems are often needed to treat nosocomial UTIs as the causative bacteria exhibit a high degree of resistance to commonly used antimicrobial agents [5,6]. Since patterns of antibiotic resistance in a wide variety of pathogenic organisms vary even over short period of time and depend on the site of isolation and different environments, periodic evaluation of antibacterial susceptibility of pathogenic bacteria is always needed. In view of the above, the current study was planned to find out the prevalence of Gram-negative uropathogens and their antimicrobial susceptibility patterns at a tertiary care hospital in Gujarat, India.
Materials and methods
The study was conducted, at a tertiary care hospital, Bhavnagar, Gujarat, India from March 2021 to February 2022.The study was approved by the Institutional Sub-Ethical Committee prior to commencement of study. Ethical approval letter No. 1050/2021. Date: 24/02/2021.
All the urine samples received for culture and sensitivity in microbiology laboratory were included in the study. Repeat urine samples from the same admission were excluded. Samples were processed immediately to ensure maximum recovery of the pathogen. Culture was performed on cystine-lactose-electrolyte deficient (CLED) agar and plates were incubated overnight at 35-370C [7]. A sample was considered culture positive if the bacterial count was ≥ 105 and ≥ 103 colony forming unit/mL (CFU/mL) for non-catheterized and catheterized patient respectively. The isolates were identified by motility and standard bio-chemical tests. Antibiotic susceptibility of organisms was performed by Kirby-Bauer disk diffusion method on Mueller-Hinton agar plates with following antibiotics: trimethoprim/sulfamethoxazole (23.75/1.25µg), nitrofurantoin (30µg), gentamicin (10µg), tobramycin (10µg ), amikacin (30µg), tetracycline (30µg), amoxicillin-clavulanic acid (20/10µg), ciprofloxacin (5µg), ofloxacin (5µg), norfloxacin (10µg), ceftriaxone (30µg), ceftazidime (30µg), cefotaxime (30µg), cefepime (30µg), piperacillin (100µg), piperacillin/tazobatum (100/10µg), and meropenem (10µg). Diameters of the zones of inhibition were interpreted according to CLSI 2022 guideline [8].
Results
During the study period, a total 4938 specimens were received of which 4332 and 606 samples were received from in-patient and outpatient department (IPD, OPD) respectively. Out of total 4938 samples, 918 (18.6%) yielded signification growth. Significant bacterial growth was present in 19.2% and 14.5% of urine samples from IPD and OPD respectively. Out of 2430 samples from male and 2508 samples from female, 383 (15.8%) and 535 (21.3%) were culture positive respectively. Out of 918 isolates, 781 (85.1%) were Gram-negative bacteria. Among the Gram-negative bacteria, most prevalent organism was Escherichia coli (61.7%) followed by Klebsiella pneumoniae (30.1%) and Pseudomonas spp (7.4%) [Table-1].
Table-1: Culture results of urine samples according to source, age, gender and types of bacteria.
Detail rate of resistance of total isolated Gram-negative uropathogens to different antimicrobial agents is shown in Table-2. Out of 781 Gram-negative bacteria, 81.2% were resistant to amoxicillin/clavulanic acid while least resistance was observed against meropenem and 3rd generation cephalosporins except ceftriaxone (Table-2).
Table-2: Pattern of resistance of total isolated Gram-negative uropathogens to different antimicrobial agents (N=781)
Escherichia coli isolates were most resistant to amoxicillin /clavulanic acid (84.6%) while resistance to ceftazidime and meropenem was 0.4% and 0.2% respectively. Out of 235 isolated Klebsiella pneumoniae, 95.3% and 51.9% were resistant toamoxicillin/clavulanic acid and trimethoprim/ sulfamethoxazole respectively. Pseudomonass pp isolates were most resistant to piperacillin (58.6%) followed by ceftazidime (34.5%). Detail antimicrobial resistance patter to different Gram-negative isolates is shown in Table-3.
Table-3: Antimicrobial resistance pattern of isolated Gram-negative bacteria (N=781)
Discussion
Effective management of UTI depends on identification of the causative organism and choosing a suitable antibiotic for the treatment. Development of resistance to commonly used antibiotics is a major concern worldwide, causing failure of treatment in different types of infections, including UTI [9]
In this study, the results show that 18.6% of the urine samples from our hospital yielded significant pathogens. The finding is similar to other reported studies [10-12]. In the present study, E. coli was the most frequently isolated organism from our urine samples. Previous studies also reported E. coli as the most common cause of UTIs in the Indian population, followed by other uropathogens like Klebsiella, Pseudomonas, Proteus, Enterococcus and Staphylococcuss species [10-14]. Resistance to amikacin observed in our study (15.5%) was closely comparable to other studies (16% - 23.9%) reported from India [12,13,15]. In the present study, 34.4% E. coli was resistant to cotrimoxazole, while in other studies across India the resistance rate was found between 48% to 56.7% [16,13]. In our study, we found low rate of resistance of E coli to nitrofurantoin (6.8%) while others reported the rate as 15.9% to 35.3% [10,12,13]. However, Sood et al [11] found the rate as 5.8%. In the current study, 38.4% of E. coli was resistant to ciprofloxacin while other studies reported the rates between 36% to 66% [16,17]. Over use of quinolones has led to this increase in resistance. We observed very low rate of resistance of E. coli to meropenem (0.2 %) when other studies reported the rate around 19% [10,13]. Meropenem is a costly drug and, therefore, less frequently used. Low rate of resistance of E. coli to ceftazidime, cefotaxime and nitrofurantoin found in our study suggests that these antimicrobial agents would be useful for empiric therapy in UTI patients. Klebsiella pneumoniae were the second most isolated uropathogens (30.08%) in our study. The findings are similar to various studies done across India [12,21]. Among the Klebsiella pneumoniae isolates, resistance to amoxycillin/clavulanic acid (95.3%) was similar to Shah D et al (90%) [12]. In our study, resistance to other antimicrobials namely meropenem, piperacillin/tazobactam and nitrofurantoin ranged between 0-12.7%. However, previous studies reported much higher rate of resistance to these antimicrobials [12,22,23]. Non-fermenter such as Pseudomonas aeruginosa is an important cause of healthcare-associated UTI. Due to good clinical practice in our hospital, the resistance rate of isolated Pseudomonas spp to different antimicrobial agents are low compared to other studies [11,21,24].
Gram-negative bacteria are the most common bacterial cause of UTI. Antimicrobial resistance to first and second line antimicrobial agents should be monitored regularly to avoid treatment failure. Overprescribing of antibiotics is associated with an increased risk of adverse effects and treatment failures due to emergence of resistant bacteria. Every center needs to carry out regular surveillance on prevalent uropathogens and their antimicrobial resistance pattern for effective therapy and control of hospital infection.
Acknowledgement
The authors would like to acknowledge the contributions of staff and laboratory personnel of the Department of Microbiology, Government Medical College, Sir Takhtasinhji Hospital, Bhavnagar, Gujarat, India-364001
Conflict of interest
Authors declared no conflict of interest
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Citer this article as:
Oza MK, Patel S, Jagad B, Jadeja R, Desai K. Antimicrobial susceptibility pattern of Gram-negative uropathogens at a tertiary care centre in Gujarat. IMC J Med Sci. 2024; 18(2):007. DOI: https://doi.org/10.55010/imcjms.18.019
