Despite the therapeutic effectiveness of antifungal agents, the incidence of fungal infections has increased during the past few decades due to the higher use of chemotherapeutic and immunosuppressive agents and organ transplantation . Out of more than 100 yeast species recognized as pathogens, only less than ten species are considered as common causes of fungal infections in humans . Candida species are the most prevalent fungal pathogens. These species, especially C. albicans, are considered as the most important cause of fungal bloodstream infection (BSI) described as candidemia.
However, the incidence of candidemia due to non-albicans species (e.g., C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei) have increased during the recent years [1, 3, 4]. In addition, Candida species are known as the fifth common cause of nosocomial infection and the fourth common cause of nosocomial BSI (8-10%) [5-7]. Despite the effectiveness of the antifungal therapy, candidemia remains an important cause of human mortality (30-60%). This increase mostly occurs among the susceptible patients with intense disruption in the immune system. This condition is mostly observed among those admitted to the Intensive Care Units (ICUs) .
There are numerous predisposing factors for candidemia some of which are more familiar such as using central venous catheter, total parenteral nutrition, prolonged and broad-spectrum antibiotic therapy, previous steroid therapy, undergoing repeated abdominal sur-geries, and low birthweight. Most of these predisposing factors usually occur when the patients are admitted to the internal medicine units and ICUs [9, 10]. Therefore, this can explain why more than 50% of all candidemia episodes occur in the patients admitted to these units .
Resistance to antifungal agents is becoming more common among the Candida spp., especially in non-albicans species such as C. glabrata, which is inherently or secondarily resistant to fluconazole. Amphotericin B is considered as a selected treatment for the systemic fungal infections; nevertheless, resistance to amphotericin B has been reported for some species such as C. lusitaniae,C. guilliermondii, and C. kefyr [12, 13]. Resistance to antifungal agents has a high impact on the fungal infection prognoses and is significantly correlated with increased treatment failure, mortality, and prolonged hospital stay.
The isolation of the Candida spp. from blood culture using traditional aerobic and anaerobic bacteriological media can detect the occurrence of candidemia. However, the chance of fungal isolation from blood stream by these media is limited and estimated to be about 50% in the patients with invasive candidiasis. Furthermore, this method requires additional blood samples, an increasing amount of incubator space, and additional processing, which are time-consuming and need more experience . On the other hand, the BACTEC blood culture system (Becton Dickinson Diagnostic Systems), which is specifically formulated for this purpose, can provide a faster and more efficient method for fungal isolation from blood stream .
Since few hospital centers in Iran are accustomed to using the automated blood culture system as their main method, the traditional aerobic and anaerobic blood cultures remain as a routine media for fungal blood culture in the majority of the hospitals. However, this method provides limited information about the Candida spp. detection and identification at the species level and their antifungal susceptibility patterns, which are necessary for the selection of appropriate antifungal medications, especially in the patients with candidemia.
Regarding this, the aim of the current study was to assess the fungal epidemiology of candidemia and the antifungal susceptibility patterns against five current antifungal agents including fluconazole, itraconazole, voriconazole, amphotericin B, and caspofungin among the patients with prolonged fever.
Materials and Methods
This cross-sectional study was conducted on 253 patients with persistent fever, who were suspected of candidemia based on the clinical symptoms, admitted to the Beheshti Educational Hospital, Kashan, Iran, during May 2011-November 2013. These patients had prolonged fever in spite of receiving broad-spectrum antibiotic therapy for more than seven days. The study procedure was approved by the Medical Research Ethics Committee of Kashan University of Medical Sciences. All the patients were enrolled in the study after obtaining their informed consents.
The demographic and clinical data collected in this study were age, gender, duration of stay in the ICU, current history of broad-spectrum antibiotic therapy for more than seven days, antifungal therapy, presence of central venous catheter (CVC), urinary catheter (UC), mechanical ventilation (MV), and history of surgery or other predisposing factors, and clinical outcomes.
During this study, 361 blood samples (i.e., approximately 20 ml for each patient) were collected aseptically from 232 patients via venipuncture using a sterile syringe after skin disinfection through a standard technique . The equal volumes of blood samples were inoculated into the following two media: the biphasic fungal media containing the brain heart infusion (BHI) broth and BHI Agar (Tebo sadegh, Kashan, Iran). Subsequently, the samples were incubated at 370C for at least two weeks and the remaining processes were implemented following the procedures previously described by Lotfi et al. . The BACTEC Myco/F Lytic culture vials (Becton Dickinson, Le Pont de Claix, France) were placed in the BACTEC 9120 System (Becton Dickinson Microbiology Systems, Maryland, DE, USA), and automatically controlled every 10 min. The conventional broth bottles and BACTEC bottles with sign of fungal growth were sub-cultured on the plates containing the BHI agar (Merck, Germany) and Sabouraud dextrose agar (Biolife, Italy) supplemented with chlor-amphenicol (0.5μg/ml) following the previously described study .
The isolated yeasts were identified at species level using morphological and physiological properties and produced color in CHROM agar Candida (bioMérieux, Marcy l’Etoile, France). Since one strain could not be identified based on the color, it was identified by polymerase chain reaction (PCR) sequencing using universal primers ITS1 (5’-TCCGTAGGTGAACCTGCGG- 3’) and ITS4 (5’-TCC TCC GCT TAT TGA TAT GC-3´) for amplification of the ITS1-5.8 S rRNA-ITS2 regions according to the method described previously by Ghahri et al. .
The PCR product was subjected to DNA sequencing with the same primers. The obtained sequences were analyzed in the GenBank database. The identified species were inoculated for further investigation into the tubes containing BHI broth with 20% glycerol and kept at -70°C.
In vitro antifungal susceptibility testing
The antifungal susceptibility testing was performed using microdilution method as recommended by the Clinical and Laboratory Standards Institute (CLSI, document M27-A3) . Interpretative breakpoints were assessed according to the MICs (µg/mL) from the 24-h M27-S4  and M27-A3 CLSI broth microdilution methods .
The antifungal drugs were obtained from the following companies: amphotericin B (Sigma-Aldrich, USA.), fluconazole (Sigma-Aldrich, USA.), itraconazole (Sigma-Aldrich, USA.), voriconazole (Pfizer Central Research, UK), and caspofungin (Merck, USA.). The selected antifungals were diluted in the standard Roswell Park Memorial Institute 1640 Medium with L-glutamine without bicarbonate (Sigma-Aldrich, USA.), buffered to pH 7.0 with 0.1653-(N-morpholino) propane sulfonic acid (MOPS) (Sigma- Aldrich, USA). Subsequently, they were dispensed in a 96-well microplate to supply twice stronger concentrations.
The final concentrations were 0.0313-16 μg/ml for amphotericin B, itraconazole, and voriconazole; 0.125-64 μg/ml for fluconazole; and 0.015-8 μg/ml for caspofungin. The Candida isolates were sub-cultured on the Sabouraud dextrose agar and incubated at 35°C overnight. Subsequently, they were suspended in 5 mL of sterile water and vigorously vortexed. The turbidity was adjusted spectrophotometrically at 625 nm to achieve the 0.5 McFarland standard (approximately 1×106 to 5×106 CFU/mL). The suspension was diluted to 0.5 × 103-0.25 × 103 CFU/mL on the RPMI-1640 medium. Then, the microplates were inoculated with 100 μL of suspension and incubated at 35°C in a humid environment for 24 h.
The MICs were visually determined and described as the lowest drug concentration, which could create a prominent decrease in turbidity, compared to the drug-free growth control well. The MICs for amphotericin B were determined as the lowest concentration at which no visible growths were detected. The clinical breakpoints (CBPs) values are not determined for all drugs in the CLSI M27-S4; therefore, the CBPs were identified based on both CLSI M27-S4 and M27-A3 broth microdilution methods.
Caspofungin MIC values of ≤ 0.25 and ≥ 1 µg/ml were determined as susceptible and resistant toC. albicans; however, these MIC values for C. glabrata were ≤ 0.12 and ≥ 0.5 µg/ml, respectively. Regarding fluconazole, these values were ≤ 2 and ≤ 8 µg/ml as susceptible and ≤ 8 and ≥ 64 µg/ml as resistant to C. albicans and C. glabrata, respectively. In addition, for voriconazole and itraconazole, MIC value of ≤ 0.12 µg/ml was defined as susceptible, whereas MIC values of ≥ 64 and ≥ 4 µg/ml were determined as resistant to C. albicans and C. glabrata, respectively. Furthermore, the C. albicans isolates with MIC value of ≥ 2 µg/ml were considered as resistant to amphotericin B. Each test was carried out in duplicates, and C. parapsilosis (ATCC 22019) and C. krusei (ATCC 6258) were used as quality controls.
During 30 months, a total of 10 episodes of candidemia were identified by BACTEC blood culture system, and six specimens were detected using the conventional culture methods. The mean age of the patients with positive cultures was 48.2±30.9 years. As the results demo-nstrated, the highest positive cultures were observed in the females (60%). Moreover, the C. albicans (5, 50%) was the most prevalent species followed byC. glabrata (4, 40%) and C. parapsilosis (1, 10%). The mean duration of hospital stay was 83.2±23 days.
Additionally, all patients had at least one underlying disease such as cancer (20%), diabetes (20%), premature birth (20%), as well as multiple trauma and vast surgery (40%). Moreover, 20% of the patients had multiple underlying diseases simultaneously such as major surgery and dialysis or diabetes and renal failure.
Among different predisposing factors, the use of central venous catheter was reported for all the patients, and the majority of the patients (80%) had the experience of antibiotic therapy during the hospital stay just before getting infected with candidemia. In addition, three patients (30%) had a medical device such as mechanical ventilation and urine catheter. As the results indicated, the mortality rate was high (60%) among these patients. Furthermore, many patients (70%) with candidemia were admitted to the ICU and Neonatal Intensive Care Unit (NICU). All the demographic and clinical data are summarized in Table1.
|Patient ID||Sex||Age (years)||Hospitalization (Month)||Hospital unit||Underline disease||Antibiotic treatment||IsolatedCandida||Medical device||MIC,µg/ml||Outcome|
|1||M||52||2||ICU||Diabetes & Renal failure||+||C. albicans||CVCMV||2||0.25||0.031||0.5||1||died|
|4||F||38||2||ICU||Multiple Trauma & Surgery||+||C. albicans||CVC||0.5||0.125||0.125||o.5||0. 125||Coma|
|5||M||24||3||ICU||Multiple Trauma & Vast Surgery& Dialysis||+||C. albicans||CVCUC||0.25||0.125||0.25||0.5||0.125||died|
|6||F||60||5||ICU||Multiple Trauma & Vast Surgery||+||C. albicans||CVC||8||8||4||0.5||2||died|
|7||F||61||3||IU||Surgery (tracheotomy)||+||C. glabrata||CVCMV||4||16||1||1||0.5||died|
|9||F||41||4||ICU||Multiple Trauma & Vast Surgery||_||C. glabrata||CVC||4||4||2||1||0.5||Coma|
|Abbreviations: ICU, intensive care unit; NICU, Neonatal intensive care unit; IU, internal unit; CVC, central venous catheter; MV, mechanical ventilation ; UC, urine catheter; MIC, minimal inhibitory concentration.|
For amphotericin B, the breakpoint was not determined; however, several studies have reported ≤ 1 μg/ml as susceptible. All isolates (100%) were found to be susceptible to amphotericin B. nevertheless, for fluconazole and voriconazole, five, four, and one isolates were susceptible (50%), susceptible-dose dependent (40%), and resistant (10%), respectively.
Furthermore, regarding the itraconazole, four, five, and one isolates were susceptible (40%) susceptible-dose dependent (50%), and resistant (10%), respectively. More resistance (50%) belonged to caspofungin; in addition, four isolates (40%) were susceptible, and one isolate (10%) was susceptible-dose dependent.
MIC ranges and geometric mean for all drugs are shown in Table 2.
Candida spp. are considered as predominant causes of candidemia, morbidity, and mortality in the patients admitted to the ICU . The high mortality rate (60%) found in the present study is in line with the findings of other studies, reporting between 38% and 76% mortality among the adults in the developing and developed countries [17, 22, 23].
|Candida species (n)||Antifungal agentMIC a, µg/ml b|
|C. albicans (5)||0.25-8(1.31)||0.125-8(0.24)||0.031- 4(0.24)||0.125-0.5(0.42)||0.125-2(0.42)|
|C. glabrata (4)||4(4)||4-16(5.65)||1-2(1.41)||0.5-1(0.84)||0.25-0.5(0.42)|
|C. parapsilosis (1)||1||0.0625||0.125||0.125||0.125|
|aAbbreviation: MIC, minimal inhibitory concentration. ; b Range (Geometric Mean).|
The results also showed that 80% of the candidemia episodes occur in the patients admitted to the ICU, which was higher than the findings of the previous Latin American and European studies reporting 56.6% and 44.4%, respectively [24, 25]. Only in one study across five sites in Italy and Spain, a low rate (19.6%) was reported for the episodes of nosocomial candidemia in the ICU patients . This discrepancy could be due to the variations in healthcare services and patients’ immune status. Moreover, this predominant number of patients with candidemia in the ICU may be related to the intensity of immunosuppressive therapy and other common risk factors for candidemia in the ICU admitted patients.
During the past decades, some studies have reported a shift to the emergence of non-albicans as the common etiology of candidemia [16, 27]. Lotfi et al. reported C. parapsilosis and C. tropicalis as the most common Candida species isolated from burn patients with candidemia . Inconsistent with their finding, C. albicans was the most common cause of candidemia found in this study. Based on the data collected for this study, C. albicans and non-albicans had an equal frequency; however, C. albicans was the predominant species. This finding is in line with that of a similar study carried out by Bassetti et al. . Furthermore, C. glabrata was isolated as a predominant species among the non-albicans species (40%). The emergence of non-albicans species could be related to some medical conditions, which varied for each species .
Previous exposure to azoles was considered as the most predisposing factor for candidemia due to C. glabrata, which was the second isolated species in our study . Therefore, empiric antibiotic therapy and such antifungal drugs as azoles, which is the common practice implemented in Beheshti Hospital, could be the greatest cause for the high prevalence of C. glabrata candidemia and limitation in candidemia detection. In several studies, C. glabrata has been reported to be more common in the elderly patients. In the present study, the minimum age of the patients with C. glabrata candidemia was 41 years, which was consistent with the reported results of the previous studies [22, 28, 29].
In our study, all strains were susceptible to amphotericin B, which is in line with the findings of some previous studies [30, 31]. However, inconsistent with this finding, several studies reported a few amphotericin B-resistant strains isolated from the patients with candidemia [32, 33]. Amphotericin B is the first choice treatment drug for candidemia in Beheshti Hospital. It is also considered as an antifungal agent with rapid fungicidal potency against the majority of Candida spp. strains, which is also inexpensive. These findings can have important and valuable implications for the healthcare systems.
According to the CLSI M27-S4, the CBPs for caspofungin susceptibility were defined at ≤ 0.25, ≤ 0.12, and ≤ 2 μg/ml for C. albicans, C. glabrata, and parapsilosis, respectively. More resistance to caspofungin (50%) was reported in this study, which is higher, compared to the results reported in other studies [11, 34].
Based on the results of several studies, caspofungin had the best effect against Candida spp. with resistance to fluconazole, itraconazole, and amphotericin B at the same time [35, 36]. A study examined the Candida spp. isolates recovered from the cancer patients with oropha-ryngeal candidiasis in the north of Iran. In the mentioned study, caspofungin had the best antifungal activity against the oropharyngeal non-albicans Candida spp. isolates, particularly among the species that had reduced susceptibility to amphotericin B, fluconazole, and itraconazole . In addition, caspofungin was recommended as a suitable treatment for the oropharyngeal candidiasis . More resistance was shown among C. glabrata isolates. However, the emergence of resistance to caspofungin among C. glabrata isolates has also been demonstrated during the treatment of a critically ill patient . Inconsistent with the findings of other studies, in the present study, an increased resistance to azole group was observed, which was higher than the reported rates in isolates from the Europe (12.6%, 6.3%) [11, 39] and North America (6.6%) .
Voriconazole, a recently-discovered drug, showed 10% resistance in the current study. However, in a study that was conducted in the largest teaching hospital in Brazil, 97% of the Candida spp. isolated from candidemia were susceptible to voriconazole . In a study carried out in a tertiary care institute in India, 56% of the Candida isolates were resistant . Several studies have shown that fluconazole-resistant strains have higher MICs for voriconazole than the fluconazole-susceptible isolates [42-44]. However, the rate of resistance reported in this study could be justified by over-the-counter or empirical therapy by azoles, especially fluconazole for vaginal candidiasis .
This study suffered from several limitations including the low number of patients and hospitals. A single center of study could be affected by local health policy; therefore, the comparison and interpretation of the findings, especially antifungal susceptibility patterns, should be carried out carefully. However, based on the findings of the present study, candidemia should be considered as a significant source of morbidity in Kashan. Regarding this, the authorities need to establish a surveillance and control program for candidemia prevention and the minimization of drug resistance.
- Ghahri M, Mirhendi H, Zomorodian K, Kondori N. Identification and antifungal susceptibility patterns of Candida strains isolated from blood specimens in Iran. Arch Clin Infect Dis. 2013; 8(3):e14529.
- Fromtling RA, Rhodes JC, Dixon DM. Taxonomy, classification, and morphology of the fungi. Manual of clinical microbiology. ASM Press: Washington, DC; 2003.
- Zirkel J, Klinker H, Kuhn A, Abele-Horn M, Tappe D, Turnwald D. Epidemiology of Candida blood stream infections in patients with hematological malignancies or solid tumors. Med Mycol. 2012; 50(1):50-5.
- Das I, Nightingale P, Patel M, Jumaa P. Epidemiology, clinical characteristics, and outcome of candidemia: experience in a tertiary referral center in the UK. Int J Infect Dis. 2011; 15(11):e759-63.
- Wisplinghoff H, Bischoff T, Tallent SM, Seifert H, Wenzel RP, Edmond MB. Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study. Clin Infect Dis. 2004; 39(3):309-17.
- Yapar N. Epidemiology and risk factors for invasive candidiasis. Ther Clin Risk Manag. 2014; 10:95-105.
- Sievert D, Ricks P, Edwards JR, Schneider A, Patel J, Srinivasan A. Antimicrobial-resistant pathogens associated with healthcare-associated infections: summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2009-2010. Infect Control Hosp Epidemiol. 2013; 34(1):1-14.
- Cheng YR, Lin LC, Young TG, Liu CE, Chen CH, Tsay RW. Risk factors for candidemia-related mortality at a medical center in central Taiwan. J Microbiol Immunol Infect. 2006; 39(2):155-61.
- Mikulska M, Del Bono V, Ratto S, Viscoli C. Occurrence, presentation and treatment of candidemia. Expert Rev Clin Immunol. 2012; 8(8):755-65.
- Mikulska M, Bassetti M, Ratto S, Viscoli C. Invasive candidiasis in non-hematological patients. Mediterr J Hematol Infect Dis. 2011; 3(1):e2011007.
- Bassetti M, Taramasso L, Nicco E, Molinari MP, Mussap M, Viscoli C. Epidemiology, species distribution, antifungal susceptibility and outcome of nosocomial candidemia in a tertiary care hospital in Italy. PLoS One. 2011; 6(9):e24198.
- Amran F, Aziz MN, Ibrahim HM, Atiqah N, Parameswari S, Hafiza M. In vitro antifungal susceptibilities of Candida isolates from patients with invasive candidiasis in Kuala Lumpur Hospital, Malaysia. J Med Microbiol. 2011; 60(9):1312-6.
- Krcmery V, Barnes AJ. Non-albicans Candida spp causing fungaemia: pathogenicity and antifungal resistance. J Hosp Infect. 2002; 50(4):243-60.
- Jones JM. Laboratory diagnosis of invasive candidiasis. Clin Microbiol Rev. 1990; 3(1):32-45.
- Chiarini A, Palmeri A, Amato T, Immordino R, Distefano S, Giammanco A. Detection of bacterial and yeast species with the Bactec 9120 automated system with routine use of aerobic, anaerobic, and fungal media. J Clin Microbiol. 2008; 46(12):4029-33.
- Ma CF, Li FQ, Shi LN, Hu YA, Wang Y, Huang M. Surveillance study of species distribution, antifungal susceptibility and mortality of nosocomial candidemia in a tertiary care hospital in China. BMC Infect Dis. 2013; 13(1):337.
- Lotfi N, Shokohi T, Nouranibaladezaei SZ, Omran AN, Kondori N. High recovery rate of non-albicans Candida species isolated from burn patients with candidemia in Iran. Jundishapur J Microbiol. 2015; 8(10):e22929.
- El-Din AZ, Mohamed AM, Walaa HG, Ghada SL. Prevalence of microbial pathogens in blood cultures: an etiological and histopathological study. J Taibah Univ Sci. 2010; 3:23-32.
- National Committee for Clinical Laboratory Standards. Reference method for broth dilution antifungal susceptibility testing of yeasts: approved standard. Clinical and Laboratory Standards Institute: Wayne, PA; 2008.
- Clinical Laboratory Standards Institute (CLSI). Reference method for broth dilution antifungal susceptibility testing of yeasts; Fourth informational supplement. CLSI document M27-S4. CLSI: Wayne; 2012.
- Bouza E, Muñoz P. Epidemiology of candidemia in intensive care units. Int J Antimicrob Agents. 2008; 32(Suppl 2):S87-91.
- Gupta A, Gupta A, Varma A. Candida glabrata candidemia: an emerging threat in critically ill patients. Indian J Crit Care Med. 2015; 19(3):151-4.
- Marriott DJ, Playford EG, Chen S, Slavin M, Nguyen Q, Ellis D. Determinants of mortality in non-neutropenic ICU patients with candidaemia. Crit Care. 2009; 13(4):R115.
- Pfaller MA, Messer SA, Moet GJ, Jones RN, Castanheira M. Candida bloodstream infections: comparison of species distribution and resistance to echinocandin and azole antifungal agents in Intensive Care Unit (ICU) and non-ICU settings in the SENTRY Antimicrobial Surveillance Program (2008–2009). Int J Antimicrob Agents. 2011; 38(1):65-9.
- Nucci M, Queiroz-Telles F, Alvarado-Matute T, Tiraboschi IN, Cortes J, Zurita J. Epidemiology of candidemia in Latin America: a laboratory-based survey. PloS One. 2013; 8(3):e59373.
- Bassetti M, Merelli M, Righi E, Diaz-Martin A, Rosello EM, Luzzati R. Epidemiology, species distribution, antifungal susceptibility, and outcome of candidemia across five sites in Italy and Spain. J Clin Microbiol. 2013; 51(12):4167-72.
- Poikonen E, Lyytikäinen O, Anttila VJ, Koivula I, Lumio J, Kotilainen P. Secular trend in candidemia and the use of fluconazole in Finland, 2004-2007. BMC Infect Dis. 2010; 10(1):312.
- Kauffman CA, Yoshikawa TT. Fungal infections in older adults. Clin Infect Dis. 2001; 33(4):550-5.
- Pfaller MA, Diekema DJ. Role of sentinel surveillance of candidemia: trends in species distribution and antifungal susceptibility. J Clin Microbiol. 2002; 40(10):3551-7.
- Thomas M, Oberoi A, Dewan E. Species distribution and antifungal susceptibility of candidemia at a multispecialty center in North India. CHRISMED J Health Res. 2016; 3(1):33.
- Giri S, Kindo A, Kalyani J. Candidemia in intensive care unit patients: a one year study from a tertiary care center in South India. J Postgrad Med. 2013; 59(3):190-5.
- Kothari A, Sagar V. Epidemiology of Candida bloodstream infections in a tertiary care institute in India. Indian J Med Microbiol. 2009; 27(2):171-2.
- Adhikary R, Joshi S. Species distribution and anti-fungal susceptibility of Candidaemia at a multi super-specialty center in Southern India. Indian J Med Microbiol. 2011; 29(3):309-11.
- Shokohi T, Badali H, Amirrajab N, Ataollahi MR, Kouhpayeh SA, Afsarian MH. In vitro activity of five antifungal agents against Candida albicans isolates, Sari, Iran. Curr Med Mycol. 2016; 2(2):34-9.
- Pfaller MA, Diekema DJ, Messer SA, Hollis RJ, Jones RN. In vitro activities of caspofungin compared with those of fluconazole and itraconazole against 3,959 clinical isolates of Candida spp, including 157 fluconazole-resistant isolates. Antimicrob Agents Chemother. 2003; 47(3):1068-71.
- Lyon GM, Karatela S, Sunay S, Adiri Y, Candida Surveillance Study Investigators. Antifungal susceptibility testing of Candida isolates from the Candida surveillance study. J Clin Microbiol. 2010; 48(4):1270-5.
- Shokohi T, Bandalizadeh Z, Hedayati MT, Mayahi S. In vitro antifungal susceptibility of Candida species isolated from oropharyngeal lesions of patients with cancer to some antifungal agents. Jundishapur J Microbiol. 2011; 4(2):S19-26.
- Krogh-Madsen M, Arendrup MC, Heslet L, Knudsen JD. Amphotericin B and caspofungin resistance in Candida glabrata isolates recovered from a critically ill patient. Clin Infect Dis. 2006; 42(7):938-44.
- Cisterna R, Ezpeleta G, Telleria O, Spanish Candidemia Surveillance Group. Nationwide sentinel surveillance of bloodstream Candida infections in 40 tertiary care hospitals in Spain. J Clin Microbiol. 2010; 48(11):4200-6.
- Messer SA, Moet GJ, Kirby JT, Jones RN. Activity of contemporary antifungal agents, including the novel echinocandin anidulafungin, tested against Candida spp, Cryptococcus spp, and Aspergillus spp: report from the SENTRY Antimicrobial Surveillance Program (2006 to 2007). Journal of clinical microbiology. 2009; 47(6):1942-6.
- Motta AL, Almeida GM, Almeida Júnior JN, Burattini MN, Rossi F. Candidemia epidemiology and susceptibility profile in the largest Brazilian teaching hospital complex. Braz J Infect Dis. 2010; 14(5):441-8.
- Cuenca-Estrella M, Rodriguez D, Almirante B, Morgan J, Planes AM, Almela M. In vitro susceptibilities of bloodstream isolates of Candida species to six antifungal agents: results from a population-based active surveillance programme, Barcelona, Spain, 2002–2003. J Antimicrob Chemother. 2005; 55(2):194-9.
- Cuenca-Estrella M, Gomez-Lopez A, Mellado E, Monzon A, Buitrago MJ, Rodriguez-Tudela JL. Activity profile in vitro of micafungin against Spanish clinical isolates of common and emerging species of yeasts and molds. Antimicrob Agents Chemother. 2009; 53(5):2192-5.
- Pfaller M, Diekema D. Epidemiology of invasive candidiasis: a persistent public health problem. Clin Microbiol Rev. 2007; 20(1):133-63.
- Nazeri M, Mesdaghinia E, Moraveji SA, Atabakhshiyan R, Soleymani F. Prevalence of vulvovaginal candidiasis and frequency of candida species in women. J Mazandaran Univ Med Sci. 2012; 22(86):255-62.