|Year : 2015 | Volume
| Issue : 3 | Page : 413-415
Fluconazole susceptibility of 3,056 clinical isolates of Candida species from 2005 to 2009 in a tertiary-care hospital
Y Ying1, J Zhang1, SB Huang2, FD Liu3, JH Liu1, J Zhang1, XF Hu4, ZQ Zhang1, X Liu1, XT Huang1
1 Department of Medical Microbiology, School of Medicine, Nanchang University, Nanchang, People's Republic of China
2 Department of Pharmacy, Medical College, Nanchang University, Nanchang, People's Republic of China
3 Department of Clinical Laboratory, Children's Hospital of Jiangxi Province, Nanchang, People's Republic of China
4 Department of Clinical Laboratory, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, People's Republic of China
|Date of Submission||04-Sep-2013|
|Date of Acceptance||13-Jan-2015|
|Date of Web Publication||12-Jun-2015|
X T Huang
Department of Medical Microbiology, School of Medicine, Nanchang University, Nanchang
People's Republic of China
Source of Support: None, Conflict of Interest: None
In recent years, Candida infections have been increasing significantly. This study was to investigate the distribution and fluconazole susceptibility of such infections. Totally, 3,056 clinical isolates were analysed, C. albicans was the most prevalent species from respiratory and vaginal specimens. However, non-albicans species constituted the majority of isolates from blood, urine, intensive care unit (ICU), organ transplant and burned patients. Similarly, Candida spp. from different specimens and clinical services had different degrees of susceptibility to fluconazole. Isolates from vagina and burned patients had the highest resistance rate, while all of the isolates from ascites and dermatological services were susceptible to fluconazole.
Keywords: Candida, epidemiology, fluconazole, susceptibility
|How to cite this article:|
Ying Y, Zhang J, Huang S B, Liu F D, Liu J H, Zhang J, Hu X F, Zhang Z Q, Liu X, Huang X T. Fluconazole susceptibility of 3,056 clinical isolates of Candida species from 2005 to 2009 in a tertiary-care hospital. Indian J Med Microbiol 2015;33:413-5
|How to cite this URL:|
Ying Y, Zhang J, Huang S B, Liu F D, Liu J H, Zhang J, Hu X F, Zhang Z Q, Liu X, Huang X T. Fluconazole susceptibility of 3,056 clinical isolates of Candida species from 2005 to 2009 in a tertiary-care hospital. Indian J Med Microbiol [serial online] 2015 [cited 2019 Aug 20];33:413-5. Available from: http://www.ijmm.org/text.asp?2015/33/3/413/158569
| ~ Introduction|| |
Candida species are the most prevalent opportunistic fungal pathogens. Recently, the incidence of Candida infections has been increased because of the immune suppression and frequent broad-spectrum antibacterial therapy. ,
Most cases of Candida infections are caused by C. albicans, but those caused by non-albicans species of Candida, such as C. glabrata, C. tropicalis and C. krusei, appear to be rising. , In addition, the widespread and long-time use of azoles has resulted in resistance to azoles.  The increased incidence of acquired resistance to azoles and the shift from C. albicans to non-albicans species may pose serious problems in the management of infections;thus, it is necessary to identify Candida spp. in clinical settings and monitor their antifungal resistance for providing appropriate treatment for candidasis. To this end, we retrospectively investigated 3,056 isolates of clinical Candida spp. at the First Affiliated Hospital of Nanchang University over a 4-year period.
| ~ Materials and Methods|| |
From January 2005 to July 2009, a total of 3,056 isolates of Candida spp. were obtained from patients with Candida infections. These isolates were identified by using CHROMagar plates and a Vitek 2 system. C. krusei ATCC 6258 and C. parapsilosis ATCC 22019 were used as quality control reference strains.
Fluconazole susceptibility was tested according to the M27-A2 broth microdilution method, as recommended by the clinical and laboratory standards institute (CLSI) (formerly NCCLS). All isolates were passed through two successive subcultures (first 48 hours and then 24 hours) on sabouraud agar (SDA) at 35°C to ensure viability and purity. Suspensions were prepared in sterile 0.85% saline and were adjusted to match the turbidity of a 0.5 McFarland standard at 530 nm wavelength. Then, the stock suspension was diluted 1:50 and further diluted 1:20 with Rosewell Park Memorial Institute (RPMI) 1640 broth medium, which result in 1.0 × 10 3 to 5 × 10 3 CFU/mL. Finally, 100 μL suspension was inoculated into each well on 96-well microplates containing 100 μL of antifungal agent and incubated at 35°C for 48 hours. The minimum inhibitory concentration (MIC) for fluconazole was defined as the lowest concentration that caused a decrease in turbidity, which corresponded to approximately 50% of the inhibition in a growth control well. According to the CLSI M27-A2 standard, isolates with MICs ≤8 ug/ml, between 16 and 32 ug/ml and ≥64 ug/m were considered susceptible, susceptible dose-dependent (S-DD) and resistant to fluconazole, respectively.
| ~ Results|| |
Among 3,056 clinical isolates, 2,170 (71.0%) isolates were identified as C. albicans, followed by C. glabrata (547, 17.9%), C. tropicalis (155, 5.1%), C. krusei (114, 3.7%), C. parapsilosis (17, 0.6%) and other Candida species (53, 1.7%). Overall, 87.7% Candida isolates were susceptible to fluconazole. The resistance rate of C. albicans, C. glabrata, C. tropicalis and C. krusei was 4.3%, 5.7%, 7.1% and 100%, respectively.
The Candida spp. isolates were collected from various clinical specimen types, including blood, urine, ascites, faecal, respiratory tract and vaginal tract specimens as shown in [Table 1], C. albicans constituted more than 65.0% of isolates from the respiratory (77.0%) and vaginal (67.0%) tract specimens. C. glabrata constituted 40.9% and 33.0% of all Candida spp. from blood and urine, respectively. C. tropicalis accounted for 12.7% of all urinary tract isolates of Candida but was less common (<7%) as an agent of candidiasis among other specimen types. The rate of fluconazole susceptibility was 91.1%, 78.6%, 87.3%, 85.3%, 90.9% for isolates from the respiratory, vaginal, urinary, digestive tract and blood, respectively.
|Table 1: Fluconazole susceptibility of Candida spp. from different specimens |
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The clinical services in this study included the intensive care unit (ICU), transplant unit, medical, surgical, haematology, oncology, urology, dermatology, burn and paediatric services. As shown in [Table 2], C. albicans mainly isolated from the patient of medical services and outpatients. Non-albicans species accounted for 62.6%, 56.3%, 78.3% of the isolates from the ICU, organ transplant and burn patients, respectively. The fluconazole-resistance rate was 6.7%, 12.0%, 4.8%, 3.1%, 7.0%, 9.3%, 14.1%, 8.3%, 30.4% and 6.7% for isolates from the medical service, outpatients, oncology service, surgical patients, ICU, the haematology service, molysmology service, urology service, burn patient and transplant service.
|Table 2: Fluconazole susceptibility of Candida spp. from different clinical services |
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| ~ Discussion|| |
In consistent with other reports,  C. albicans was found to be the predominant pathogen in this study. However, it is noteworthy that the distribution of Candida spp. varied among different specimen types and different clinical services. In the present study, C. albicans was the species most commonly isolated from the respiratory, vaginal and digestive specimens, but non-albicans species represented 68.2% and 53.8% of isolates from blood and urinary tract. Similarly, although C. albicans was still the most prevalent species in most of the clinical services, the non-albicans species were the dominant pathogens isolated from the ICU (62.6%), organ transplant (56.3%) and burn patients (78.3%). The increased prevalence of non-albicans Candida species causing invasive candidasis has been widely reported in many studies ,, and may have a profound effect on future clinical outcomes because some non-albicans Candida species have been correlated with higher virulence and mortality than C. albicans.
Our data indicated that the activity of fluconazole against Candida species remains high. However, the susceptibility of Candida spp. from different specimens and clinical services varied. The resistance rates of isolates from the different clinical services varied from 0.0% to 30.4%. Notably, the resistance rate for isolates from the vagina, burn patients, molysmology patients and outpatients were very high. Previous investigators have reported that fluconazole resistance in vaginal C. albicans isolates is rare. , However, in our survey, 14.6% of the C. albicans strains displayed decreased susceptibility to fluconazole. The high resistance rate in vaginal C. albicans isolates may be associated with repeated exposure to antifungal agents. Meanwhile, in this study, the percentage of non-albicans vaginitis (31.8%) was higher than in previous reports, , and these species appeared to have high resistance to fluconazole.
In conclusion, the Candida spp. distribution and fluconazole susceptibility varied among the various specimen types and clinical services. These observations suggest that continuous monitoring the epidemiology of Candida spp. is necessary as well as the assessment of the antifungal susceptibility.
| ~ Acknowledgments|| |
We thank Doctor Wanzhen Liao, and members of the Department of Clinical Laboratory of the First Affiliated Hospital of Nanchang University for supplying the clinical isolates. This study was supported by the National Natural Science Foundation of China (No. 30660010 and 81160196), the Young Scientists Training Program of Jiangxi Province (20133BCB23005), and the Science and Technology Foundation of Jiangxi Province (20142BAB215053).
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[Table 1], [Table 2]