Pediatric Candiduria: Insights from an observational study at a tertiary care hospital in northwestern India

Abstract

BACKGROUND

Pediatric candiduria is a frequently overlooked manifestation of healthcare-associated fungal infections. Candida species are increasingly being identified in the urine of neonates and infants, with non-albicans Candida (NAC) species being more prevalent than Candida albicans.

AIM

To determine the rate of Candida species isolation among pediatric patients with suspected urinary tract infections (UTI) at a tertiary care hospital.

METHODS

A total of 436 children with a clinical suspicion of UTI were enrolled in this laboratory-based descriptive observational study. The samples were then subjected to urine mounting and subcultured on Sabouraud dextrose agar. Candida isolates were identified based on the color of the colonies on CHROM agar, Dalmau plate culture, and germ tube formation. The results were confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry, followed by Antifungal susceptibility testing using Vitek^® 2 AST-YS07 cards.

RESULTS

A total of 79 Candida isolates (18.12%) were identified. Of these, 39 (49.37%) were neonates, with a male-to-female ratio of 3.39:1. The intensive care unit (ICU) recorded 52 patients (65.82%). Of the 79 patients, 57 (72.15%) received broad-spectrum antibiotics for more than 7 days. Our study revealed a higher prevalence of NAC species, with Candida tropicalis accounting for 34 cases (43.04%). Amphotericin B showed the highest susceptibility, with 68 isolates (86.08%) being susceptible to this Antifungal agent.

CONCLUSION

Pediatric patients with Candiduria present atypical and vague symptoms. This may be the initial symptom of disseminated Candidiasis in the presence of predisposing factors. Isolation of these pathogens, along with their Antifungal susceptibility patterns, aids in a better prognosis.

Key Words: Urinary tract infections; Funguria; Candiduria; Non-albicans Candida; Antifungal susceptibility

Core Tip: This study provides region-specific data on the prevalence, species distribution, and antifungal susceptibility patterns of Candiduria in pediatric patients at a tertiary care hospital in Northwestern India. The predominance of non-albicans Candida species, particularly Candida tropicalis, and the association with risk factors such as prolonged antibiotic use and intensive care admission, underscore the need for early recognition and appropriate antifungal stewardship. These findings contribute to a more nuanced understanding of pediatric Candiduria in resource-limited settings.

INTRODUCTION

Urinary tract infections (UTI) are a leading cause of infection worldwide and a significant contributor to global health challenges, affecting individuals of all ages. The term "candiduria" refers to the presence of Candida species in the urine. Candida species naturally inhabit the human oral cavity, gastrointestinal tract, and lower genital tract as a commensal. However, the presence of Candida species in urine is considered Candiduria, and its severity varies from asymptomatic Candiduria to clinical sepsis.

Yeasts may be present in urine due to contamination, bladder colonization, or upper UTI resulting from retrograde or hematogenous spread from distant sources. Therefore, it is crucial to differentiate between contamination from commensal and Candida UTI. Identifying the specific Candida species that causes UTI before initiating treatment is essential. This is particularly important given the rising prevalence of non-albicans Candida (NAC) species, many of which are resistant to fluconazole therapy[1,2].

Although bacterial causes of UTI are more prevalent than Candida UTIs, there is an emerging trend in fungal species that contribute to UTI. This increase can be attributed to factors such as excessive use of antibiotics, advances in medical care, compromised immune function, and emergence of Antifungal drug resistance. Additional predisposing factors for Candiduria in neonates include low birth weight, prolonged hospitalization, and total parenteral nutrition. Furthermore, underlying renal conditions, diabetes, and other medical issues can increase the risk of infant Candiduria. Given these trends, there is a growing need for speciation and regional surveillance of Antifungal drug susceptibility profiles to improve management of such cases.

In children over two years of age, the classic presentation of cystitis or pyelonephritis can be observed. However, in newborns, the symptoms and signs are non-specific and may include poor feeding, diarrhea, failure to thrive, vomiting, mild jaundice, lethargy, fever, and hypothermia. Neonatal sepsis is an uncommon, yet potential complication of Candiduria. Similarly, UTI may present with non-specific symptoms in infants, such as fever, GI symptoms, or foul-smelling urine. As a result, UTI in infants may be missed owing to vague symptoms[3].

Few studies have explored the distribution of Candida spp. and their susceptibility patterns in infants and neonates. One such study in North India revealed that while Candida albicans was the most prevalent species, Candida tropicalis, which is often resistant to multiple drugs, was more common in intensive care unit (ICU) settings[4]. Another study from Italy investigated 299 invasive Candida infections in 262 patients at a tertiary-care pediatric hospital[5].

There is still limited research on Candida UTI in India. Considering the pediatric literature regarding nosocomial infections in developing nations, this study aimed to shed light on the magnitude of the problem and risk factors associated with the pediatric population. We also examined the speciation and Antifungal susceptibility patterns of the isolates.

MATERIALS AND METHODS

Study design

This laboratory-based observational study was conducted from July 2023 to December 2023 at tertiary care hospital, located in northwestern India, within the Department of Microbiology after approval from the Institutional Ethics Committee (Office order No. 100/MC/EC/2020). The sample size was calculated in advance using prevalence data reported by Yadav et al[3], who studied Candiduria in a similar pediatric population.

Urine samples from patients with suspected UTI (clinical manifestations like dysuria, urgency, frequency, flank pain, or fever) aged 0-14 years from the neonatal ICU (NICU), paediatric ICU, wards, and outpatients with a duly filled requisition form with demographic details (age, sex, and admission status), along with indications for sample submission, were obtained from the microbiology laboratory. Other predisposing factors such as birth weight, transplant, steroid treatment, duration of broad-spectrum antibiotics, and hospital stay were also assessed.

Inclusion and exclusion criteria

The study included patients aged under 14 years presenting with urinary symptoms (fever, vomiting, irritability), who had complete requisition forms with demographic and clinical details, and exhibited pure creamy white Candida growth with colony-forming units (CFU) greater than 10³. Patients older than 14 years and those with bacterial or mixed growth in samples were excluded.

Sample processing

A total of 436 patients participated in the present study, ranging from newborns to patients aged up to 14 years old. The identification of pus and yeast cells was achieved through the examination of wet mount and KOH mount preparations, respectively. Urine samples were cultured semi-quantitatively on Sabouraud dextrose agar plates with an inoculating loop (internal diameter of 1.33 mm, delivering 0.001 mL of urine) and examined after 18-24 hours of incubation at 37 °C. Candida species were isolated based on colony morphology, Gram staining, and microscopy.

Species identification and antifungal drug susceptibility

Species identification was performed by demonstrating the germ tube for Candida albicans, micro-morphology in cornmeal agar (Dalmau plate culture), and colony color on CHROM agar, and confirmed using the MALDI VITEK MS (bioMérieux, Marcy l'Étoile, France) assay. Antifungal susceptibility testing was performed using Vitek^® 2 AST-YS07 cards (bioMérieux; Marcy l’Etoile, France). The Antifungal drugs tested were fluconazole, voriconazole, caspofungin, micafungin, flucytosine, and Amphotericin B.

Statistical analysis

Patient information and laboratory findings were entered into Microsoft Excel. Quantitative variables were presented as means and standard deviations, whereas qualitative values were presented as proportions (%). The χ² test was used to assess the association between two qualitative or categorical variables. Statistical significance was set at P < 0.05.

RESULTS

A total of 79 patients (18.12%) with Candida species were isolated from the urine samples of 436 patients. Among the urine samples, direct microscopy revealed the presence of budding yeast cells in 71 participants.

Of the total isolates, 43 (54.43%) had a colony count exceeding 10⁵ CFU/mL, whereas 28 (35.44%) and 8 (10.13%) isolates had colony counts in the range of 10⁴-10⁵ CFU/mL and 10³-10⁴ CFU/mL, respectively. The identification results obtained using the conventional methods and MALDI-TOF MS were consistent. The male-to-female ratio was 3.39:1, with 39 participants (49.37%) being under one month old, and 30 (37.97%) of these were located in the NICU (Table 1).

Table 1 Distribution of patients as per age, gender, location and direct microscopy findings.

Variables	Number of participants	%
Sex
Male	61	77.22
Female	18	22.78
Total	79	100.00
Age
Neonate (< 1 month)	39	49.37
Infant (1 month to 1 year)	21	26.58
1-5 years	9	11.39
5-10 years	5	6.39
10-14 years	5	6.39
Total	79	100.00
Location
Neonatal intensive care unit	30	37.97
Paediatric intensive care unit	22	27.85
In-patient department	22	27.85
Out-patient department	5	6.33
Total	79	100.00
Colony counts (colony forming unit/mL)
103-104	8	10.13
104-105	28	35.44
>105	43	54.43
Total	79	100.00
Pus cells
Absent	12	15.19
Present	67	84.81
Total	79	100.00

Of the 17 Candida albicans isolates, 9 (52.94%) were reported from the ward, making it the most commonly isolated species from the ward. Conversely, in ICUs, Candida tropicalis was the predominant isolate, accounting for 24 (70.59%) of the 52 isolates from the ICU (Table 2). Overall, there was a predominance of NAC, with Candida tropicalis being the most prevalent, comprising 34 isolates (43.04%) (Table 3).

Table 2 Distribution of Candida isolates as per gender.

Candida species isolated	Males	Females	Total	%
Candida albicans	13	4	17	21.52
Candida glabrata	14	4	18	22.78
Candida krusei	1	0	1	1.27
Candida parapsilosis	7	2	9	11.39
Candida tropicalis	26	8	34	43.04
Total	61	18	79	100.00

Table 3 Distribution of Candida isolates as per locations.

Species	IPD	NICU	OPD	PICU	Total
Candida albicans	9	5	2	1	17
Candida glabrata	4	8	0	6	18
Candida krusei	0	0	0	1	1
Candida parapsilosis	2	4	0	3	9
Candida tropicalis	7	13	3	11	34
Total	22	30	5	22	79

IPD: Inpatient department; NICU: Neonatal intensive care unit; OPD: Outpatient department; PICU: Pediatric intensive care units.

Birth history was available for 60 out of 79 patients with Candiduria, of whom 25 had low birth weight. The spectrum of underlying medical conditions exhibited significant heterogeneity, with some cases presenting with two or more risk factors. Notably, 22 patients (27.85%) had lung disease, and 11 (13.92%) had renal anomalies. The predominant predisposing factor in this study was that the majority of the patients, comprising 57 individuals (72.15%), were administered broad-spectrum antibiotics for more than 7 days. Additionally, 21 patients (26.58%) had extended hospital stays lasting between 8 days to 3 months. Clinical manifestations were diverse, with 50 cases (63.29%) presenting with fever, followed by 24 cases (30.38%) reporting crying during micturition, and 22 (27.85%) reporting abnormal breathing (Table 4).

Table 4 Patient characteristics with predisposing factors, medical history and clinical manifestations.

Variables	Total	Percentage
Birth weight (up to 1 year old patients)
Birth weight in normal range (> 2500 g)	35	58.34
Low birth weight (1500-2500 g)	8	13.34
Very low birth weight (< 1500 g)	10	16.67
Extremely low birth weight (< 1000 g)	7	11.67
Medical history
Lung disease	22	27.85
Renal anomalies	11	13.92
Congenital heart disease	7	8.86
Chronic liver disease	7	8.86
Post transplant	7	8.86
Type 1 diabetes mellitus	4	5.06
Malignancy	3	3.80
No remarkable medical history	27	34.18
Predisposing factors1
Broad spectrum antibiotics	57	72.15
Prolonged hospital stay > 15 days	21	26.58
Steroids	18	22.78
Catheterisation	14	17.72
Clinical manifestations1
Fever	50	63.29
Cry	24	30.38
Abnormal breathing	22	27.85
Poor feeding	18	22.78
Vomiting	9	11.39
Diarrhoea	7	8.86
Foul smell urine	6	7.59
Failure to thrive	3	3.80
Mild jaundice	3	3.80
Hypothermia	2	2.53

¹More than 1 variable present in single patient.

Effective management of neonatal candiduria involves the use of appropriate Antifungal therapy and preventive measures to minimize the likelihood of systemic Candidiasis. Results from Antifungal susceptibility testing indicated that the majority of the isolates were susceptible to Amphotericin B (Table 5).

Table 5 Antifungal susceptibility testing of isolates, n (%).

Result	Resistant	Susceptible	Total
Fluconazole	12 (15.19)	67 (84.81)	79
Voriconazole	13 (16.46)	66 (83.54)	79
Caspofungin	16 (20.25)	63 (79.75)	79
Micafungin	26 (32.91)	53 (67.09)	79
Amphotericin B	11 (13.92)	68 (86.08)	79
Flucytosine	11 (13.92)	68 (86.08)	79

DISCUSSION

Candida species are unusual causes of UTI in healthy individuals but are common in hospital settings or among patients with predisposing diseases and structural abnormalities of the kidney and collecting systems[6]. In India, Candida species are the fifth most common nosocomial urinary pathogen[7]. A total of 79 Candida isolates (18.12%) were identified in the present study, which is in accordance with other studies in Iran and New Delhi[8,9].

Here, the maximum number of cases were seen in children under the age of one year which could be due to the fact that neonates and infants are at a higher risk of funguria because of decreased immunity at this age. Similar findings have been reported in other studies worldwide[8-11]. In addition, the overall male-to-female ratio was 3.39:1, indicating that male sex is a risk factor for Candiduria in the pediatric age group, which has also been reported in other studies[9-11]. Although colony counts ≥ 10⁵ CFU/mL were observed in 54.43% of isolates, quantitative counts alone do not reliably distinguish contamination or colonization from true infection in Candiduria. Diagnosis should be guided by clinical symptoms, risk factors, and species identification, as high counts may also be seen in asymptomatic colonization. Some studies suggest that Candiduria defined at ≥ 10³ CFU/mL may be clinically relevant, yet asymptomatic cases often resolve with catheter removal alone, without antifungal therapy[12]. However, studies from Iran and India have concluded that urine colony counts are ineffective in predicting the likelihood of invasive disease[10,11].

Candida isolates were predominantly obtained from ICUs, with 30 cases (37.97%) originating from NICU. This observation may be attributed to the critical condition of ICU patients, their exposure to multiple broad-spectrum antimicrobial therapies, and the prevalent use of catheters, which increase the risk of infection by introducing microorganisms during insertion or post-placement manipulation of the urinary catheter. All these are significant risk factors for Candiduria, further predisposing individuals to candidemia. Colonization is recognized as a significant predisposing factor for the development of candidemia, which is associated with a substantial mortality rate ranging from 46% to 80%, surpassing the mortality rate observed in cases of bacteremia (38%)[13]. Furthermore, it is imperative to acknowledge that Candiduria should not be overlooked in septic patients, as it may serve as an early indicator of an underlying systemic Candida infection[6].

Prolonged courses of broad-spectrum antibiotic therapy were observed in 57 patients (72.15%), which emerged as the primary predisposing factor, followed by a prolonged hospital stay in 21 cases (26.58%). In pediatric patients, a history of antibiotic use is a universal risk factor. The substantial risk factors in our study were the same as those reported by other authors with similar findings[9,10].

In the past decade, NAC has taken over Candida albicans as the primary etiology of Candiduria; this trend was also observed in the present study, which accounted for 62 cases (78.5%), which aligns with various other studies conducted across diverse geographical regions[9,10,14]. However, a complete explanation for this shift in species distribution has not yet been fully elucidated. However, this may be linked to their varying virulence capabilities and resistance to Antifungal treatments[15]. Geographical variations in the etiological patterns of invasive Candida infections have been documented in different countries. Candida glabrata is predominant in North America, whereas Candida parapsilosis and Candida tropicalis are predominant in South America[16]. Therefore, identification of Candida species is essential for establishing a localized database for a specific geographic region.

Fluconazole resistance in Candida is alarming, as it is a useful drug because of its high concentration in the urine and better tolerability. As reported by Rex et al[17], resistance to fluconazole can potentially be attributed to prior exposure to the drug. Fluconazole is often the initial treatment of choice owing to its relatively low toxicity compared to other Antifungal medications, resulting in its widespread use in clinical settings. This extensive use can lead to the development of resistant strains[17]. In Candida albicans, studies have shown that mutations in the ergosterol synthesis pathway and increased activity of drug efflux pumps contribute to resistance. However, other unknown factors may also play a role.

NAC species like Candida tropicalis, Candida parapsilosis, Candida krusei, and Candida glabrata have similar genes involved in drug resistance, but these genes may behave differently in each species. The role of efflux pumps and mutations in resistance-related genes like ERG11 is still not fully understood in NAC species. As resistance continues to rise, more research is needed to understand how different Candida species develop azole resistance so that better treatment strategies can be developed. A study conducted by Berkow et al[18] observed that in the past two decades, several genes and mutations have been identified that increase resistance to fluconazole in clinical isolates, primarily in Candida albicans.

In India, the antifungal resistance landscape in Candida isolates remains poorly defined due to a lack of multi-centric studies. However, one study from India reported fluconazole resistance in 30.8% of cases, whereas our study observed 16.46% azole resistance[19]. Amphotericin B resistance is a significant concern, particularly when certain fungal species exhibit resistance to fluconazole. In such cases, Amphotericin B is the secondary treatment choice. Nonetheless, as noted by Safdar et al[20], cautious administration of this drug is necessary, and it should be reserved for situations with confirmed resistance to other Antifungal agents because of its considerable toxicity[20]. NAC species have a wide resistance profile to the azole groups of Antifungal drugs. Similar findings were reported in other studies[21,22]. Variances in resistance patterns could stem from varying degrees of antifungal usage within each region, with hospital-acquired strains often displaying elevated levels of resistance.

Currently, there are no definitive guidelines for detecting Candida UTI. Knowledge of patient symptoms is the key to ruling out contamination from true infections. The medical records of patients should be assessed and correlations with potential risk factors should be determined. Preventive strategies for pediatric Candiduria include minimizing unnecessary use of indwelling urinary catheters, implementing strict catheter care protocols, and promoting judicious use of broad-spectrum antibiotics to reduce fungal colonization and infection risk.

The limitations of this study include its reliance on data from a single center, which may restrict the applicability of the conclusions to broader populations with different healthcare practices. Furthermore, the relatively small sample size of 436 patients along with lack of control group and the exclusion of individuals with mixed growth or bacterial infections could limit the ability of this study to reach definitive conclusions regarding pediatric Candiduria. Additionally, the absence of long-term follow-up precludes the assessment of outcomes beyond initial diagnosis and treatment.

CONCLUSION

In our study, we concluded that non-albicans species are predominant and more resistant to Antifungal agents than Candida albicans. Thus, the identification of yeasts up to the species level has become increasingly important for diagnostic laboratories, because the changing epidemiology of Candida infections highlights the need to monitor the species distribution and susceptibility of Candida to optimize therapy. Candiduria appears to be of little importance in generally healthy patients; however, in high-risk patients, careful evaluation of disseminated infections is warranted. Pediatric Candiduria torments children, agitates parents, and raises concerns for clinicians. It presents with vague, atypical symptoms. This may be an initial symptom of disseminated candidiasis in the presence of predisposing factors. The isolation of these pathogens, as well as their Antifungal susceptibility patterns, aids in the early diagnosis of disseminated candidiasis and treatment of Candiduria for a better prognosis in these cases.

ACKNOWLEDGEMENTS

We thank the laboratory staff at SMS Medical College for their valuable assistance with specimen processing and culture work.