Candida species could cause severe infections with high morbidity and mortality in hospitalized patients (
2-
4).
Candida albicans was reported as the most isolated species from infected patients in this study and other studies in Asian, European, and American countries (
3,
5,
11-
14). A global increase was seen in the number of infections caused by species other than
C. albicans, including
C. tropicalis, C. parapsilosis, C. glabrata, and
C. krusei(8, 15).
Candida tropicalis was the second isolated
Candida species in this study. The epidemiology of this species was reported as 15.3% in Brazil(
16), 13.4% in Iran (
17), and 8.4% in Italy (
18).
Amphotericin B is a polyene antifungal drug with high activity against a wide variety of fungal pathogens. The sensitivity rates of
C. albicans to AMB in this study was 96.6% (271.9/273), and in other studies, this was reported as 97.4% (37/38), 96.6% (113/117), 100% (93/93), and 93% (160/172) (
11,
15,
19,
20). The sensitivity rate of
C. glabrata in this study was 88.9% (16/18) and in other studies, this was reported as 85% (34/40) and 93.8% (15/16) (
6, 11). This rate for
C. krusei was 70% (7/10) in the present study and 90% (56/62) in the other studies (
6). The differences in sensitivity rates could be due to patient population or type of the study. Given the limited number of isolates in non-
albicans species, high resistant rate may not be reliable enough.
Echinocandins are a new line of antifungal drugs. According to Espinel-Ingrof et al. (2013), use of the CLSI species-specific CAS breakpoint could lead to results indicating an excessive number of sensitive isolates (such as
C. glabrata and
C. krusei) as resistant. Therefore, they suggested that routine testing or reporting of CLSI CAS MICs for
Candida, according to CLSI (2012), is not suitable (
21). Generally, in this study, CAS was an effective agent against
Candida species, except some
C. glabrata and
C. krusei species (MIC90 = 2 µg/mL). The MIC90 values of this drug for
C. glabrata and
C. krusei were reported as 0.19 and 0.75 µg/mL in colonized isolates in 2014 (
15); 4 and 1 µg/mL in patients hospitalized at ICUs and urology wards (
22); and 0.125 and 0.25 µg/mL in patients with cancer (
11). In this study, all isolates were from infected patients and this is the reason for the differentiation between the studies.
Antifungal resistance may occur due to cross-reactivity of azole antifungal agents. Such a trend was reported using FLU and ITR as prophylaxis or treatment in patients, leading to resistant species, and treatment with other azoles failed. Resistance rate to FLU varied in different studies and for
C. glabrata it was reported as 95% (38/40), 6.2% (1/16) and 10.3% (6/58 with 52/58 susceptible dose dependent) (
6,
11,
23). These rates for
C. krusei were 95.2% (59/62) (
6).
Candida krusei is naturally resistant to antifungal drugs, especially FLU (
24). In the current study, ITR resistance rate in
C. albicans was 12.7% (34.7/273) with dose dependent susceptibility of 35.3% (96/273). This rate was reported as 15.1% (26/172), 5.4% (2/38), 28% (36/117) and 11.9% (18/167) in other studies (
6,
11,
15,
25). Itraconazole resistance rates in
C. glabrata and
C. krusei in the present study were 77.8% (14/18) and 33.3% (3/10), and in other studies, these were 85% (34/40) and 85.5% (53/62), and 50% (7/14) and 30% (6/18), respectively (
6,
15). Voriconazole is a drug of choice for the treatment of filamentous fungi and it has a good activity against fluconazole-resistant
C. glabrata strains (
26). According to literature, low resistance rate of VOR for
Candida species was reported (
6,
14,
27).
Ketoconazole showed significant toxicity as a systemic drug, so it is only available as a topical drug (cream and shampoo) for the treatment of cutaneous fungal infections (
26). Posaconazole and KET do not have any breakpoint mentioned in CLSI M27-S4 reference (
10). Previously, highest MIC values for KET were reported in
C. krusei (4 µg/mL) (
15) and
C. albicans (32 and 2 µg/mL) (
15,
28). The difference could be explained by the sample size and study population, e.g., in immunocompromised cases, like HIV patients, the resistance rate to anti-fungal agents was high (
28). In this study, highest MIC90 value for POS was observed in
C. glabrata (2 µg/mL), as in a previous study (
15). In a study from 70 medical centers around the world, the highest MIC90 value for POS was reported in
C. glabrata with 2 µg/mL (
29).