Antifungal susceptibility patterns of colonized Candida species isolates from immunocompromised pediatric patients in five university hospitals.

BACKGROUND AND OBJECTIVES: Colonization of Candida species is common in pediatric patients admitted to hematology-oncology wards. The aim of this study was to identify colonized Candida species and their susceptibility patterns in hematologic pediatric patients.
MATERIALS AND METHODS: Samples were collected from mouth, nose, urine and stool of the patients admitted to five university hospitals and cultured on sabouraud dextrose agar. The isolates were identified by API 20 C AUX system and their susceptibility patterns were evaluated by CLSI M27-A3 and S4.
RESULTS: From 650 patients, 320 (49.2%) were colonized with 387 Candida species. Candida albicans was the most prevalent isolated species, followed by Candida glabrata, Candida tropicalis, Candida famata, Candida kefyr and Candida kuresi. The epidemiological cut off value (ECV) for all Candida species to amphotericin B was ≤0.25 μg except C. krusei (4 μg). The resistance rate to fluconazole in this study in C. albicans was 4.9% with ECV 8 μg/ml, followed by C. tropicalis 8.8% with ECV 0.5 μg/ml. Voriconazole and posaconazole were effective antifungal agents for all Candida isolates. The ECV of C. albicans, Candida parapsilosis, C. tropicalis, C. glabrata and C. krusei for itraconazole were 0.5, 0.25, 0.5, 1 and 2 μg, respectively. The resistant and intermediate rates of Candida species to caspofungin in this study were 2.9%, 5.9%, 18.8%, 47.9%, 0.0% and 16.7% in C. tropicalis, C. glabrata and C. parapsilosis respectively.
CONCLUSION: C. albicans was the most prevalent species in pediatric colonized patients. New azole agents like voriconazole and posaconazole are effective against non-albicans Candida species. Increase in intermediate species is alarming to future emerging resistant species.

INTRODUCTION

Candida species are the main cause of superficial to systemic fungal infection in humans and the major source of infection in health care centers (1). Systemic infections are common in immunocompromised pediatrics individuals including patients in hematology-oncology wards (1, 2). According to Center for Diseases Control and Prevention (CDC), Candida species is ranked fifth among hospital-acquired pathogens and forth among blood stream infection pathogens (3). The colonized patients are most susceptible to infection. The rates of Candida colonization were reported 48.8%, and 78.8% in pediatric hematologic patients (4, 5).

C. albicans is the main pathogenic agent of systemic infections, however, during the recent years, the rate of non albicans Candida species has increased in many reports (2, 5, 6). Improvement in diagnostic technical methods has led to diagnosis of other Candida species. And also, C. albicans is susceptible to most antifungal agents and during the prophylaxis cleaned from the patient’s body, but non-albicans Candida species like C. glabrata and C. krusei are resistant and more emerging in the infected patients.

Caggiano et al. reported “surveillance cultures are useful to monitor the Candida colonization in ICU patients” (7, 8). Colonization with Candida species is recognized as a risk factor for systemic candidiasis in immunocompromised patients (8). The susceptibility of Candida species varies, depending on certain species responsible for infection, geographic region, patient population and health care management in each region. Limited studies have investigated the rate of colonization and susceptibility patterns of Candida species isolated from colonized children. The aim of this study was to identify Candida species isolated from colonized hematologic pediatric patients and investigate their susceptibility patterns to seven anti-fungal agents in five university hospital centers by Clinical and Laboratory Standards Institute (CLSI).

MATERIALS AND METHODS

Colonizing isolate was defined as Candida species isolated from the body site of patients without any signs and symptoms of infection.

Sample collection.

The present study was conducted from 2014 to 2015 in order to investigate the fungal colonization from immunocompromised children admitted to five university hospitals in Iran (Shiraz, Kerman, Yasouj, Ahvaz and Sannandaj). Totally, 1950 samples were collected from mouth, nose, urine and anus. Samples were cultured on Sabouraud dextrose agar (Merck, Darmstadt, Germany) and transferred to Prof. Alborzi Clinical Microbiology Research Center for further examination. To evaluate the purity of isolates, the samples were cultured on potato dextrose agar (OXOID LTD, Basind stoke, Hampshire, England) twice at 35°C for 48h. The isolates were identified by carbohydrate assimilation reactions on API 20 C AUX system (bioMerieux, Swiss), according to the manufacturer’s instructions.

Antifungal susceptibility testing.

The susceptibility patterns of the isolates against amphotericin B, fluconazole, ketoconazole, voriconazole, itraconazole, caspofungin and posaconazole (GmbH-Steinheim-SiGMA-Aldrichmie) were investigated using broth micro dilution assay, according to CLSI M27-A3 and S4 guidelines (9, 10). C. parapsilosis ATCC22019 and C. krusei ATCC6258 were considered as standard strains. The final concentrations of amphotericin B, itraconazole, posaconazole and voriconazole were ranged from 0.032 to 16 μg/ml and for fluconazole and caspofungin from 0.125 to 64 μg/ml and 0.016 to 8 μg/ml, respectively. In each series, one negative control without any yeast suspension and one positive control without any drugs were considered. The plates were sealed and incubated for 24 and 48h at 35°C and visual minimum inhibitory concentration (MIC) end points were determined. The recommended end-point for azole and caspofungin are the lowest drug concentration with a prominent decrease in turbidity (inhibitory concentration that gives 50% growth reduction), while for amphotericin B, MIC was the drug concentration showing a complete inhibition of growth. According to CLSI M27-A3 and S4, there is not any breakpoint for posaconazole and ketoconazole (9, 10).

Statistical analysis.

Statistical analysis was performed using WHO NET (version 5.6). Epidemiological cutoff value (ECV), Wild-type (WT) and non-WT strain, MIC50 and MIC90 value and Geometric Mean (GM) were reported.

Ethical considerations.

The ethics committee of Professor Alborzi Clinical Microbiology Research Center, Shiraz University of Medical Sciences reviewed and approved the study.

RESULTS

From 650 pediatric patients, 1950 samples were cultured and 320/650 (49.2%) were colonized with Candida species in different parts of their bodies and 387 Candida species isolated. The most prevalent backgrounds of patients were acute lymphoblastic leukemia, followed by lymphoma, and acute myelocytic leukemia (Table 1). All immunocompromised patients entered in this study had history of admission in the hospital and use of fluconazole for treatment or prophylaxis. C. albicans (223, 57.6%) was the most prevalent isolated species, followed by C. glabrata 48 (12.4%), C. tropicalis 34 (8.7%), C. famata 23 (5.9%), C. kefyr 18 (4.6%), C. kuresi 13 (3.3%), C. parapsilosis 12 (3.1%), C. dubliniensis 10 (2.5%), C. guilliermondii 3 (0.7%), C. lisitaniae 2 (0.5%) and C. intermedia 1 (0.25%) (Fig. 1). Distribution of Candida species isolated from each university hospital was shown in Table 2. According to Table 3, the sensitivity rates for C. albicans, the most frequently isolated species, were 99.1% to amphotericin B, 96.9% to caspofungin with 2.7% intermediate dose, 91% to voriconazole with 3.6% intermediate dose, 90.6% to fluconazole with 4.5% intermediate dose, 73.1% to itraconazole with 24.2% intermediate dose. MIC90 values for posaconazole and ketoconazole were 0.032 μg/ml and 0.125 μg/ml with GM 0.031 and 0.032, respectively. ECV in C. albicans for amphotericin B, caspofungin, and fluconazole were 0.25μg/ml, 0.25, and 0.5μg/ml, respectively. Few non-WT types’ C. albicans was isolated from the patients. According to Table 4, ECV for all Candida species to amphotericin B was ≤0.25 μg except C. krusei (4μg). The ECVs and WT rates of C. albicans, C. parapsilosis, C. tropicalis, C. glabrata and C. krusei for itraconazole were 0.5μg/ml, 96%; 0.25μg/ml, 100%; 0.5 μg/ml, 98%; 1μg/ml, 96%, 2μg/ml and 92% respectively. Other Candida species (C. kefyr, C. guilliermondii, C. lisitaniae and C. intermedia) were sensitive to antifungal agents and resistant rate to itraconazole in C. famata was 4.3%.

Table 1.

Distributions of background illness of immunocompromised patients in five university hospitals in Iran

Background illness	City
	Kerman	Shiraz	Yasouj	Sannandaj	Ahvaz
Acute lymphoblastic leukemia	28	58	26	41	20
Lymphoma	16	15	16	13	7
Acute myeloid
leukemia	8	22	3	7	9
*Others	27	21	12	22	16
Total	79	116	57	83	52

Others: Hodgkin’s lymphoma, Aplastic anemia, Burkit lymphoma, Yolk sac cancer, Megaloblastic anemia, Sarcoma

Fig. 1.

Distributions of Candida species isolated from pediatric patients.

*Others: C. parapsilosis, C. guilliermondii, C. lusitaniae, C. intermedia

Table 2.

Distributions of Candida species isolated from five university hospitals in the selected cities

Species	No. of isolates	City
		Kerman	Shiraz	Yasouj	Sannandaj	Ahvaz
C. albicans	223 (57.6%)	41	78	26	50	28
C. glabrata	48 (12.4%)	8	13	12	14	1
C. tropicalis	34 (8.7%)	7	4	12	3	8
C. famata	23 (5.9%)	11	3	2	3	4
C. kefyr	18 (4.6%)	4	3	----	8	3
C. krusei	13 (3.3%)	5	6	----	2	----
C. parapsilosis	12 (3.1%)	1	4	1	1	5
Others	16 (4.1%)	2	5	4	2	3
Total	387	79	116	57	83	52

Others: C. parapsilosis, C. guilliermondii, C. lusitaniae, C. intermedia

Table 3.

Antifungal susceptibility patterns of Candida species isolated from pediatric patients by CLSI breakpoint.

Species	Antifungal agents	Rang (μg/ml)	%R	%I	%S	MIC 50	MIC 90	Geom. Mean
C. albicans	Amphotericin B	0.016–32	0.9	0	99.1	0.032	0.25	0.039
	Caspofungin	0.016–64	0.4	2.7	96.9	0.016	0.25	0.041
	Voriconazole	0.016–16	5.4	3.6	91	0.016	0.064	0.035
	Fluconazole	0.016–64	4.9	4.5	90.6	0.125	2	0.254
	Posaconazole	0.016–16	----	----	----	0.016	0.032	0.031
	Itraconazole	0.016–16	2.7	24.2	73.1	0.032	0.125	0.049
	Ketoconazole	0.016–16	----	----	----	0.016	0.125	0.032
C. glabrata	Amphotericin B	0.016–0.5	0	0	100	0.032	0.064	0.31
	Caspofungin	0.016–0.5	18.8	47.9	33.3	0.125	0.5	0.113
	Voriconazole	0.016–0.5	0	0	100	0.032	0.025	0.05
	Fluconazole	0.064–16	0	0	100	1	4	0.842
	Posaconazole	0.016–16	----	----	----	0.064	0.5	0.082
	Itraconazole	0.032–16	14.6	72.9	12.5	0.25	1	0.233
	Ketoconazole	0.016–16	----	----	----	0.032	0.125	0.037
C. tropicalis	Amphotericin B	0.016–0.5	0	0	100	0.016	0.125	0.033
	Caspofungin	0.016–4	2.9	5.9	91.2	0.032	0.25	0.046
	Voriconazole	0.016–16	8.8	5.9	85.3	0.016	0.125	0.033
	Fluconazole	0.064–64	8.8	5.9	85.3	0.125	4	0.302
	Posaconazole	0.016–16	----	----	----	0.016	0.25	0.035
	Itraconazole	0.016–16	2.9	38.2	58.8	0.064	0.5	0.078
	Ketoconazole	0.016–16	----	----	----	0.016	0.25	0.029
C. famata	Amphotericin B	0.016–1	0	0	100	0.032	0.25	0.037
	Caspofungin	0.016–0.25	0	0	100	0.016	0.25	0.035
	Voriconazole	0.016–1	0	0	100	0.016	0.125	0.034
	Fluconazole	0.032–8	0	0	100	0.125	4	0.268
	Posaconazole	0.016–0.5	----	----	----	0.016	0.064	0.031
	Itraconazole	0.016–1	4.3	21.7	73.9	0.064	5	0.064
	Ketoconazole	0.016–0.5	----	----	----	0.016	0.125	0.03
C. kefyr	Amphotericin B	0.016–1	0	0	100	0.016	0.064	0.03
	Caspofungin	0.016–2	0	0	100	0.016	0.25	0.031
	Voriconazole	0.016–0.125	0	0	100	0.016	0.032	0.021
	Fluconazole	0.064–2	0	0	100	0.125	1	0.185
	Posaconazole	0.016–0.125	----	----	----	0.016	0.032	0.021
	Itraconazole	0.016–0.25	0	22.2	77.8	0.032	0.125	0.037
	Ketoconazole	0.016–0.16	----	----	----	0.016	0.064	0.021
C. krusei	Amphotericin B	0.032–4	38.5	0	61.5	0.025	4	0.386
	Caspofungin	0.016–0.5	0	7.7	92.3	0.125	0.25	0.092
	Voriconazole	0.032–16	7.7	0	92.3	0.25	0.5	0.238
	Fluconazole	0.25–64	0	0	----	4	64	6.817
	Posaconazole	0.016–16	----	----	----	0.25	0.5	0.214
	Itraconazole	0.064–16	15.4	69.2	15.4	0.25	2	0.346
	Ketoconazole	0.032–16	----	----	----	0.125	4	0.33
C. parapsilosis	Amphotericin B	0.016–0.25	0	0	100	0.016	0.032	0.027
	Caspofungin	0.016–4	0	16.7	83.3	0.5	4	0.282
	Voriconazole	0.016–0.25	0	8.3	91.7	0.016	0.032	0.025
	Fluconazole	0.064–2	0	0	100	0.25	2	0.298
	Posaconazole	0.016–0.5	----	----	----	0.032	0.032	0.03
	Itraconazole	0.016–0.25	0	41.7	58.3	0.064	0.125	0.06
	Ketoconazole	0.016–0.032	----	----	----	0.016	0.032	0.02
Others	Amphotericin B	0.016–1	0	0	100	0.032	0.064	0.032
	Caspofungin	0.016–1	0	0	100	0.032	0.064	0.040
	Voriconazole	0.016–0.125	0	0	100	0.032	0.032	0.026
	Fluconazole	0.064–8	0	0	100	0.25	0.5	0.227
	Posaconazole	0.016–0.064	----	----	----	0.016	0.032	0.023
	Itraconazole	0.016–0.25	0	23.1	76.9	0.032	0.25	0.042
	Ketoconazole	0.016–0.064	----	----	----	0.016	0.032	0.022

R: Resistant, I: Intermediate, S: Susceptible, MIC: Minimum inhibitory concentration.

There is no breakpoint for Posaconazole and Ketoconazole, only MIC was reported.

Table 4.

CLSI Clinical breakpoints and epidemiological cut off values for common Candida species

Antifungal	Organism	S	SDD	I	R	ECV	WT	NWT
Amphotericin	C. albicans	1≥	….	….	1≤	0.25	≥0.25 (98%)	>0.25 (2%)
	C. parapsilosis	1≥	….	….	1≤	0.25	≥ 0.25 (100%)	>0.25 (0%)
	C. tropicalis	1≥	….	….	1≤	0.25	≥ 0.25 (95%)	>0.25 (5%)
	C. glabrata	1≥	….	….	1≤	0.064	≥ 0.064 (97%)	>0.064 (3%)
	C. krusei	1≥	….	….	1≤	4	≥ 4 (100%)	>4 (0%)
	Others	1≥	….	….	1≤	0.064	≥0.064(92%)	>0.064(8%)
Caspofungin	C. albicans	0.25≥	….	0.5	1≤	0.25	≥ 0.25 (96%)	>0.25 (4%)
	C. parapsilosis	2≥	….	4	8≤	4	≥ 4(100%)	>4 (0%)
	C. tropicalis	0.25≥	….	0.5	1≤	0.5	≥ 0.5 (98%)	>0.5 (2%)
	C. glabrata	0.125≥	….	0.25	0.5≤	0.5	≥ 0.5(98%)	>0.5 (2%)
	C. krusei	0.25≥	….	0.5	1≤	0.5	≥ 0.5 (100)	>0.5 (0%)
	Others	2≥	….	4	8≤	0.064	≥0.064(92%)	>0.064(8%)
Voriconazole	C. albicans	0.12≥	….	0.25–0.5	1≤	0.064	≥ 0.064 (95%)	>0.064 (5%)
	C. parapsilosis	0.12≥	….	0.25–0.5	1≤	0.032	≥ 0.032 (91%)	>0.032 (9%)
	C. tropicalis	0.12≥	….	0.25–0.5	1≤	0.125	≥0.125 (92%)	>0.125 (8%)
	C. glabrata	ECV 0.5 μg/ml WT: MIC ≤ ECV, non-WT MIC>ECV×				0.25	0.25(96%)≥	>0.25 (4%)
	C. krusei	0.5≥	….	1	2≤	0.5	≥ 0.5 (93%)	>0.5 (7%)
	Others	….	….	….	….	0.125	≥0.125(100%)	0.125 (0%)
Fluconazole	C. albicans	2≥	….	4	8≤	8	≥ 8 (94%)	>8 (6%)
	C. parapsilosis	2≥	….	4	8≤	0.5	≥ 0.5 (84%)	>0.5 (16%)
	C. tropicalis	2≥	….	4	8≤	4	≥ 4 (92%)	>4(8%)
	C. glabrata	….	32≥	….	64≤	4	≥ 4 (95%)	>4 (5%)
	C. krusei	It is resistance to fluconazole.				64	≥64 (100%)	>64 (0%)
	Others	….	….	….	….	0.5	≥0.5(92%)	>0.5(8%)
Itraconazole	C. albicans	0.12≥	0.25–0.5	….	1≤	0.5	≥ 0.5 (96%)	>0.5 (5%)
	C. parapsilosis	0.12≥	0.25–0.5	….	1≤	0.25	≥ 0.25 (100%)	>0.25 (0%)
	C. tropicalis	0.12≥	0.25–0.5	….	1≤	0.5	≥ 0.5 (98%)	>0.5 (2%)
	C. glabrata	0.12≥	0.25–0.5	….	1≤	1	≥ 1 (96%)	>1 (4%)
	C. krusei	0.12≥	0.25–0.5	….	1≤	2	≥ 2 (92%)	>2 (8%)
	Others	0.12≥	0.25–0.5	….	1≤	0.032	≥0.032(93%)	>0.32(7%)
Posaconazole	C. albicans	There is no breakpoint, only MIC was reported.				0.25	≥ 0.25(95%)	>0.25(5%)
	C. parapsilosis					0.032	≥0.032(92%)	>0.032(8%)
	C. tropicalis					1	≥1(98%)	>1(2%)
	C. glabrata					1	≥1(95%)	>1(5%)
	C. krusei					0.5	≥0.5(93%)	>0.5(7%)
	Others					0.064	≥0.064(100%)	>0.064(0%)
Ketoconazole	C. albicans	There is no breakpoint, only MIC was reported.				0.25	≥0.25(95%)	>0.25(5%)
	C. parapsilosis					0.032	≥0.032(100%)	>0.032(0%)
	C. tropicalis					0.5	≥0.5(97%)	>0.5(3%)
	C. glabrata					0.125	≥0.125(96%)	>0.125(4%)
	C. krusei					16	≥16(100%)	>16(0%)
	Others					0.032	≥0.32(93%)	>0.32(7%)

S: Susceptible, SSD: Susceptible dose dependent, I: Intermediate, R: Resistant, ECV: Epidemiological cut off value; WT: Wild type, NWT: Non-wild type

DISCUSSION

For the management of systemic candidiasis in immunocompromised patients, early diagnosis and empirical antifungal therapies are in focus. Leon et al. reported multifocal colonization (OR=3.04, 95% CI, 1.45–6.39) was predictive of proven Candida infection and would benefit from early antifungal therapy (11). As the colonized Candida may transfer to pathogen due to change in patients’ immune system, knowledge about identification and antifungal susceptibility patterns of colonized organism can be helpful for best therapy and less resistance. C. albicans was the most prevalent species in all cities. C. glabrata was the second isolate from Shiraz, Yasouj and Sannandaj but C. famata and C. tropicalis were the second isolates from Kerman and Ahvaz. The prevalence rate of C. albicans in different studies were reported 48.6% (172/354) (12), 51.2% (117/229) (13) and 79.1% (53/67) (14). Emergence of non-albicans species in recent decades has been rising. The most prevalent non-albicans Candida isolates in the present study were C. glabrata, C. tropicalis, C. famata, C. kefyr and C. krusei (Table 2). In our study, 43.1% of all Candida isolates was non albicans species, while the rates in other studies were reported 48.8 % (13), 45% (15) and 21.8% (16). In the study conducted by Wisplinghoff et al. C. parapsilosis (17.4%), C. glabrata (16.7%) and C. tropicalis (10.2%) were responsible for bloodstream infections (18). The sensitivity rates of 178 C. albicans isolated from immunocompromised patients were reported 93%, 95.4%, 93% and 97.7% for amphotericin B, fluconazole, itraconazole, and voriconazole, respectively (17). In another study by Moran et al. “Children with non-albicans bloodstream infections were approximately twice as likely to die as children with C. albicans bloodstream infections (35.2% versus 18.2%; P= 0.03)”(19). The mortality rates of non albicans Candida bloodstream infection in children were reported 29.7%, 41.7% and 57.1% for C. parapsilosis, C. tropicalis and C. glabrata, respectively (19). Distributions of Candida species are different according to region and patient’s populations. Therefore, identification of Candida species isolated from pediatric patients is valuable in each region.

Amphotericin B is a common antifungal agent recommended for fungal infection therapy but its use has some limitations due to the risk of toxicity. In the present study, most of Candida species isolates were susceptible to amphotericin B except C. albicans and C. krusei with resistance rates of 0.9% and 38.5%, respectively.

In the Candida species isolated from immunocompromised patients the resistance rates to amphotericin B were reported 7% (12/172) in C. albicans, 10% (6/62) in C. krusei, 15% (6/40) in C. glabrata, 22.3% (4/18) in C. parapsilosis and 33.3% (2/6) in C. tropicalis (12). While these rates in colonized pediatric patients were reported 3.4% (4/117), 27.7% (5/18) and 7.1% (1/14) in C. albicans, C. krusei and C. glabrata, respectively (13).

Fluconazole is a triazole agent that is the most prescribed antifungal agents for the treatment of Candida infections. Other azoles antifungal agents include voriconazole, posaconazole and itraconazole. The resistance rate to fluconazole in this study in C. albicans was 4.9% with MIC90 value 2 μg/ml and ECV 8 μg/ml, followed by C. tropicalis 8.8%, MIC90 value 4 μg/ml and ECV 0.5 μg/ml. The resistance rates in C. albicans to fluconazole were reported 12% (14/117) in colonizing isolates in neutropenic patients, 9.3% (16/354); and 81% (43/53) in infecting isolates (12–14). In Wisplinghoff et al. report 100% of C. glabrata, 4.9% of C. tropicalis, 2.9% of C. parapsilosis and 0.8% of C. albicans were not susceptible to fluconazole (18). The resistance rate of C. glabrata to fluconazole was reported 36% with 64% susceptible dose dependent (20). The acquired resistance to fluconazole (29.4%; P<0.05) is reported in C. glabrata isolates from colonized oral cavity in patients exposed to azoles (21). The increase resistance rate of Candida species to fluconazole maybe due to the frequent use of its medication. Voriconazole is an active azole antifungal agent against Candida species. In the present study, its susceptibility rate in C. glabrata and C. krusei, as the resistant Candida species, were 100%, (MIC50: 0.032 μg and MIC90: 0.016μg), and 92.3% (MIC50: 0.25 and MIC90: 0.5), respectively. The non-susceptible rates of Candida species to voriconazole were reported 9.8% of C. tropicalis, 7.6% of C. parapsilosis, 5.0% of C. krusei and 0.6% of C. albicans (18). In study done by pfaler et al., only C. krusei was resistant to voriconazole and other Candida species were susceptible to it (22). There is no breakpoint for posaconazole and ketoconazole, according to CISI M27 S4(10). Posaconazole is the newest triazole antifungal and very expensive in our region. All Candida species had MIC value between 0.032 and 0.5 μg/ml. Candida glabrata MIC90 values for posaconazole and ketoconazole were 0.5 μg/ml and 0.125 μg/ml with GM 0.082 μg/ml and 0.037 μg/ml, respectively. MIC90 value and GM for C. tropicalis to posaconazole and ketoconazole were 0.25 μg/ml and 0.25 μg/ml; and 0.035 μg/ml and 0.029 μg/ml, respectively. The MIC values for posaconazole were reported 0.016 μg/ml, 0.25 μg/ml, 0.125 μg/ml and 0.5 μg/ml in C. albicans, C. tropicalis, C. parapsilosis and C. glabrata, respectively (23). Posaconazole and voriconazole are used limitedly and are effective on Candida species isolates from the patients.

The sensitivity rates of C. glabrata and C. krusei to itraconazole were 12.5% (with 72.9% intermediate dose) and 15.4% (with intermediate dose 69.2%), respectively. The resistance rates to itraconazole in colonized species were reported 28% (36/117), 30% (6/18) and 50% (7/14) in C. albicans, C. krusei and C. glabrata, respectively (13). These rates were reported 86% (80/93), 59.5% (25/42) and 7.7% (2/26) in C. albicans, C. glabrata and C. parapsilosis, respectively (24). The increase in intermediate rates is alarming for future resistant strains. Ketoconazole is mostly used as a topical due to its side effects for humans. In the present study, the MIC90 values for all Candida species to ketoconazole were ≤0.25μg/ml except C. krusei which was 4 μg/ml. The resistance rates for this drug in C. glabrata and C. albicans were reported 33.3% (14/42) and 17.2% (16/93) respectively (24).

Of the echinocandin antifungal agents, caspofungin is more prescribed in our region. The resistant and intermediate rates of Candida species to caspofungin in this study were 0.4% and 2.7%; 2.9% and 5.9%; 18.8% and 47.9%; and 0.0% and 16.7% in C. albicans, C. tropicalis, C. glabrata and C. parapsilosis, respectively. Other Candida species were susceptible to caspofungin. C. krusei has intrinsic resistance to fluconazole and has been shown the highest sensitivity to caspofungin and voriconazole (S=93.3%). In Korean patient, none of the Candida species was resistant to caspofungin (25).

CONCLUSiON

Colonizing Candida species may be present as reservoir for future systemic candidiasis. In the present study, 49.2% of pediatric patients wit hematologic disorders were colonized with Candida species. C. albicans was the most prevalent species in pediatric colonized patients. New azole agents like voriconazole and posaconazole are effective to non-albicans Candida species. Increase in intermediate species is alarming to future emerging resistant species. The information about distribution and susceptibility patterns of species can be useful to appropriate treatment in hematopoietic pediatric patients at the duration of infection when sampling is impossible.