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- DOI 10.18231/j.ijmmtd.2024.044
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CrossMark
Uropathogenic Candida: Microbial profile and antifungal sensitivity patterns in a tertiary care hospital in Vadodara, Gujarat
- Author Details:
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Saurabh Chhotalal Norris
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Dhwani Vasantkumar Patel
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Monika Lavjibhai Mavani
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Binda Prakashbhai Pipaliya *
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Tanuja Bakul Javadekar
Saurabh Chhotalal Norris
Dhwani Vasantkumar Patel
Monika Lavjibhai Mavani
Binda Prakashbhai Pipaliya *
Abstract
Introduction: Fungal urinary tract infections (UTIs) are commonly caused by Candida species, with Candida albicans historically recognized as the most frequently isolated species. Differentiating between mere colonization and true infection—identifying whether the Candida is a uropathogen or a commensal—is essential for appropriate clinical management. Antifungal sensitivity testing is critical in guiding effective treatment, particularly in the face of increasing resistance.
Objective: The objective of this study was to analyze the microbial profile of candiduria, distinguish between uropathogenic and commensal Candida isolates, and evaluate their Antifungal sensitivity patterns at a tertiary care hospital in Vadodara, Gujarat.
Materials and Methods: This retrospective study was conducted over a one-year period, from January 1, 2022, to December 31, 2022. A total of 9,227 urine samples from patients suspected of having UTIs were analyzed. Isolation and identification of Candida species were performed using established microbiological methods, including culture on selective media and biochemical testing. Antifungal sensitivity testing was conducted following the Clinical and Laboratory Standards Institute (CLSI) guidelines using the broth microdilution method. Patient clinical data were reviewed to differentiate uropathogenic isolates from commensals based on factors such as colony counts, presence of symptoms, and associated risk factors.
Results: Out of the 9,227 urine samples analyzed, 2,751 (29.82%) exhibited significant microbial growth, with Candida species isolated in 67 (2.43%) of these cases. Of the 67 Candida isolates, 45 (67.16%) were identified as uropathogens, while 22 (32.84%) were categorized as commensals. Candida albicans was identified in 24 (35.82%) of the isolates, while non-albicans species accounted for 43 (64.18%), including C. tropicalis (25.37%), C. parapsilosis (20.90%), C. glabrata (11.94%), and C. krusei (5.97%). Antifungal sensitivity testing showed high sensitivity to echinocandins (caspofungin and micafungin), with varying resistance patterns observed for azoles and amphotericin B among different species.
Conclusion: The study reveals a predominance of non-albicans Candida species in cases of candiduria and emphasizes the importance of accurate species identification and Antifungal sensitivity testing. Differentiating between uropathogenic and commensal isolates is vital for guiding appropriate treatment. Continuous monitoring is necessary to detect emerging resistance trends and to inform treatment strategies.
Introduction
The genus Candida comprises over 150 species, with approximately 20 known to cause infections in humans.[1] Candida albicans is traditionally recognized as the most common opportunistic fungal pathogen responsible for a variety of infections, including urinary tract infections (UTIs).[2] Candiduria, the presence of Candida species in urine, is frequently encountered in both hospital and community settings, with reported prevalence ranging from 1% to 10% among all urine samples processed in clinical microbiology laboratories.[3], [4]
Differentiating between colonization and true infection is a significant clinical challenge. While candiduria may represent mere colonization or contamination, it can also indicate invasive disease, particularly in high-risk populations such as critically ill patients, those with indwelling urinary catheters, diabetics, and individuals receiving broad-spectrum antibiotics.[5], [6] Accurate identification of Candida species and determination of their pathogenic role are essential for effective patient management.
In recent years, there has been a notable shift in the epidemiology of candiduria, with non-albicans Candida species emerging as significant pathogens.[7] These species often exhibit reduced susceptibility or inherent resistance to commonly used antifungal agents, particularly azoles, complicating treatment decisions.[8], [9], [10], [11], [12] Therefore, Antifungal sensitivity testing plays a critical role in guiding appropriate therapy and improving patient outcomes.
This study aims to elucidate the microbial profile of candiduria in a tertiary care hospital in Vadodara, Gujarat, distinguish between uropathogenic and commensal isolates based on clinical and microbiological criteria, and assess their Antifungal sensitivity patterns to inform effective treatment strategies.
Aim
To determine the microbial profile of candiduria, differentiate between uropathogenic and commensal isolates, and assess their antifungal sensitivity patterns in a tertiary care hospital in Vadodara, Gujarat.
Objectives
To identify and quantify the Candida species in urine specimen from patients with suspected UTIs.
To classify the Candida isolates as uropathogens or commensals based on clinical data, colony counts, and patient symptoms.
To evaluate the antifungal sensitivity of Candida by standard testing methods.
Materials and Methods
Study design and setting
This study employed a retrospective cross-sectional approach, spanning from January 1, 2022, to December 31, 2022, at a tertiary care facility located in Vadodara, Gujarat. The Institutional Ethics Committee approved the study.
Sample collection
We collected a total of 9,227 urine samples from patients of various ages and genders who presented with suspected urinary tract infections across different hospital departments, including both inpatient and outpatient settings.
Inclusion criteria
Patients exhibiting clinical symptoms indicative of a urinary tract infection (e.g., dysuria, frequent urination, urgency, suprapubic discomfort, fever).
Patients with identified risk factors such as indwelling urinary catheters, diabetes mellitus, immunosuppression, recent antibiotic usage, or extended hospital stays.
Exclusion criteria
Repeated samples from the same patient within a 7-day window.
Samples with insufficient volume or collected improperly.
Sample processing
Urine sample collection
Midstream clean-catch urine samples were gathered in sterile, leak-proof containers using standard aseptic methods.
For patients with catheters, samples were obtained aseptically from the catheter port with sterile syringes.
Microscopic examination
Uncentrifuged urine samples were analyzed under a microscope using wet mounts and Gram staining to identify yeast cells and pseudohyphae.
Culture techniques
Samples were plated onto Cysteine Lactose Electrolyte Deficient (CLED) agar and Sabouraud Dextrose Agar (SDA) using a calibrated loop to deliver 0.001 mL of urine.
The plates were incubated aerobically at 37°C for 24-48 hours.
Colony counts were assessed, with ≥104 CFU/mL for catheterized patients and ≥105 CFU/mL for non-catheterized patients considered significant.
Identification of candida species
Preliminary identification
Yeast colonies were examined for morphological traits on SDA and Chromogenic Candida Agar (HiCrome Candida Differential Agar, HiMedia, India), which allowed presumptive identification based on colony color:
C. albicans: Light to medium green
C. tropicalis: Metallic blue to purple
C. glabrata: Pink to purple
C. krusei: Light pink, dry, and rough
Germ tube test
Suspected yeast colonies were inoculated into human serum and incubated at 37°C for 2 hours to test for germ tube formation, indicating C. albicans or C. dubliniensis.
Cornmeal agar morphology
Chlamydospore formation was evaluated by culturing isolates on Cornmeal Agar with Tween 80 and incubating at 25°C for 48-72 hours.
Automated identification
Final species identification was verified using the VITEK 2 Compact System (BioMérieux, France) with the YST identification card, adhering to the manufacturer's guidelines.
Quality control was conducted using standard reference strains (C. albicans ATCC 90028, C. tropicalis ATCC 750, C. glabrata ATCC 2001, and C. krusei ATCC 6258).
Antifungal sensitivity Testing
Methodology
Antifungal sensitivity was assessed using the CLSI M27-A3 broth microdilution method.
The antifungal agents tested included:
Fluconazole
Voriconazole
Amphotericin B
Caspofungin
Micafungin
5-Flucytosine
Procedure
Yeast suspensions were adjusted to match a 0.5 McFarland standard and diluted to 0.5 x 10^3 to 2.5 x 10^3 CFU/mL.
Antifungal agents were prepared in RPMI 1640 medium with MOPS buffer at the required concentrations.
Microdilution plates were incubated at 35°C and assessed visually after 24 and 48 hours.
Minimum Inhibitory Concentrations (MICs) were determined:
For azoles and 5-flucytosine: Lowest concentration showing ≥50% reduction in turbidity compared to the control.
For echinocandins and amphotericin B: Lowest concentration achieving 100% inhibition of visible growth.
Interpretation
MIC values were interpreted using CLSI M60 guidelines (2017).
Isolates were classified as Susceptible (S), Intermediate (I), or Resistant (R) based on the breakpoint criteria.
Quality control strains included C. parapsilosis ATCC 22019 and C. krusei ATCC 6258.
Differentiation between Uropathogenic and commensal candida isolates
Criteria for uropathogenicity
Significant colony counts (≥105 CFU/mL for non-catheterized and ≥104 CFU/mL for catheterized patients).
Presence of urinary symptoms (e.g., dysuria, urgency, frequency, hematuria, suprapubic pain).
Risk factors for candiduria (e.g., indwelling urinary catheter, recent antibiotic use, diabetes mellitus, immunosuppression).
Criteria for commensalism
Low colony counts (<105 CFU/mL for non-catheterized and <104 CFU/mL for catheterized patients).
Absence of urinary symptoms and relevant risk factors.
Colonization in asymptomatic individuals without systemic signs of infection.
Results
Microbial profile of candiduria
We identified 67 Candida isolates from the 9,227 urine samples, representing a candiduria prevalence of 2.43%. Among these, Candida albicans was isolated in 24 cases (35.82%), while non-albicans species predominated, accounting for 43 cases (64.18%).
The distribution of non-albicans Candida species was as follows
C. tropicalis: 17 cases (25.37%)
C. parapsilosis: 14 cases (20.90%)
C. glabrata: 8 cases (11.94%)
C. krusei: 4 cases (5.97%)
|
Candida Species |
Fluconazole Susceptibility (%) |
Caspofungin Susceptibility (%) |
Micafungin Susceptibility (%) |
Voriconazole Susceptibility (%) |
Resistance Observed |
|
C. albicans |
95.83 |
100 |
- |
- |
None |
|
C. tropicalis |
70.59 |
94.12 |
100 |
- |
None |
|
C. parapsilosis |
Variable (78.57) |
85.71 |
- |
78.57 |
Azoles |
|
C. glabrata |
Resistant |
100 |
- |
- |
Fluconazole |
|
C. krusei |
Resistant |
100 |
- |
- |
Fluconazole |
|
Criteria |
Uropathogenic Candida |
Commensal Candida |
|
Colony Count |
≥10^5 CFU/mL (non-catheterized) ≥10^4 CFU/mL (catheterized) |
<10^5 CFU/mL (non-catheterized) <10^4 CFU/mL (catheterized) |
|
Urinary Symptoms |
Present (dysuria, urgency, frequency, hematuria, suprapubic pain) |
Absent |
|
Risk Factors |
Indwelling urinary catheter, recent antibiotic use, diabetes mellitus, immunosuppression |
None or minimal risk factors |
|
Clinical Relevance |
Indicative of possible infection |
Likely colonization |
Differentiation between uropathogenic and commensal isolates
Based on clinical and microbiological criteria, 45 isolates (67.16%) were classified as uropathogens, while 22 isolates (32.84%) were considered commensals. C. albicans was more frequently associated with uropathogenicity (16/24, 66.67%), whereas non-albicans species were more commonly isolated as commensals.
Antifungal sensitivity patterns
Antifungal sensitivity testing revealed the following patterns:
C. albicans isolates were highly susceptible to fluconazole (95.83%) and caspofungin (100%), with no resistance to amphotericin B observed.
Among non-albicans species, C. tropicalis showed 70.59% susceptibility to fluconazole and 94.12% susceptibility to caspofungin, while 100% of isolates were susceptible to micafungin.
C. parapsilosis isolates exhibited variable resistance to azoles, with 78.57% susceptible to voriconazole and 85.71% susceptible to caspofungin.
C. glabrata and C. krusei demonstrated inherent resistance to fluconazole and were fully susceptible to echinocandins.
Discussion
Candiduria, though often perceived as benign colonization, can represent invasive infection in certain patient populations. [13] The clinical significance of candiduria, therefore, depends on various factors, including colony counts, patient symptoms, and underlying risk factors. [14]
The present study demonstrates a predominance of non-albicans Candida species in candiduria cases, consistent with recent epidemiological trends worldwide. [15] The high isolation rate of C. tropicalis and C. parapsilosis highlights the shifting landscape of candiduria, with these species increasingly recognized as important Uropathogens. [16], [17]
Antifungal sensitivity testing remains a critical tool in managing candiduria, particularly given the rising incidence of antifungal resistance.[18] In our study, echinocandins demonstrated the highest efficacy against Candida isolates, while azole resistance was notably higher among non-albicans species, particularly C. glabrata and C. krusei. [19], [20]
The study underscores the importance of distinguishing between uropathogenic and commensal Candida isolates. Clinical and microbiological criteria, including colony counts and patient symptoms, are essential in guiding appropriate management decisions.[21] While echinocandins may offer a robust treatment option for invasive candiduria, the use of azoles should be guided by susceptibility results, particularly in the context of non-albicans species.
Continuous surveillance of antifungal resistance patterns in candiduria is imperative to inform empirical therapy and improve patient outcomes.
Conclusion
The study highlights a significant shift in the microbial profile of candiduria, with non-albicans Candida species emerging as predominant pathogens. Differentiating between uropathogenic and commensal isolates based on clinical and microbiological criteria is crucial for appropriate management. Antifungal sensitivity testing remains essential, particularly in the context of rising resistance to azoles. Ongoing surveillance and tailored treatment protocols are necessary to address the evolving landscape of candiduria.
Ethical Approval
This study was conducted under approval of Sumandeep Vidhyapeeth stitutional Ethics Committee (SVIEC/ON/Medi/RP/Aug/24/1).
Conflict of Interest
None.
Source of funding
None.
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- Abstract
- Introduction
- Aim
- Objectives
- Materials and Methods
- Study design and setting
- Sample collection
- Inclusion criteria
- Exclusion criteria
- Sample processing
- Identification of candida species
- Antifungal sensitivity Testing
- Differentiation between Uropathogenic and commensal candida isolates
- Results
- Microbial profile of candiduria
- The distribution of non-albicans Candida species was as follows
- Differentiation between uropathogenic and commensal isolates
- Antifungal sensitivity patterns
- Discussion
- Conclusion
- Ethical Approval
- Conflict of Interest
- Source of funding
- References