vulvovaginal candidiasis ( vvc ) is a common illness attributed to an overgrowth of candida species , and it is estimated that 75% of all women will experience an episode of vvc in their lifetimes . c. albicans accounts for 8095% of all episodes of vvc worldwide [ 1 , 2 ] . albicans candida species previously ranged from 5 to 20% ; however , the number of reported cases has increased sharply over the last two decades , particularly for cases of c. glabrata [ 3 , 4 ] . the emergence of resistance may be attributed to the following factors ( i ) the widespread use of over - the - counter ( otc ) medications ; ( ii ) long - term use of suppressive azoles ; and ( iii ) the frequent use of courses of antifungal medications [ 1 , 3 ] or ( iv ) the increase use of vaginal cultures for reliable diagnoses [ 2 , 5 ] . there is no evidence to suggest the followings : ( i ) certain women may be more susceptible to infection by particular candida species over other species , or ( ii ) there are epidemiologic factors that may predispose women to acute vvc ( avvc ) versus recurrent vvc ( rvvc ) [ 1 , 2 ] . vvc is also , albeit infrequently , caused by c. parapsilosis , c. tropicalis , and c. krusei [ 1 , 6 , 7 ] . the decreased susceptibility of bloodstream c. krusei isolates to amphotericin b and 5-flucytosine as determined using the broth microdilution method is well documented . however , in vitro susceptibility testing has not been used to evaluate the clinical response of c. krusei vaginitis . in addition , little is known about vaginal c. krusei infections because they are relatively rare . however , c. krusei is known to be inherently resistant to one of the most commonly used antifungal drugs , fluconazole . the signs and symptoms of c. krusei vaginitis appear to be indistinguishable from the signs and symptoms of vvc cases caused by other candida species [ 6 , 10 ] . although rare , c. krusei is an intractable cause of rvvc . furthermore , most institutions have had limited experience with c. krusei vaginitis . , we retrospectively analyzed the epidemiological characteristics of 28 vaginal c. krusei isolates , including host and risk factors . in addition , we investigated the antifungal susceptibility profiles of these isolates to 10 antifungal drugs to determine the most appropriate therapeutic choice(s ) in women with c. krusei vaginitis . we examined 1,543 vaginal samples from unrelated women , of which 560 ( 36.3% ) were culture - positive and 983 ( 63.7% ) were culture - negative for candida yeasts , and the medical records of these cases were reviewed . among the 560 vaginal yeast isolates , c. albicans was the most common species and identified in 242 ( 43.2% ) isolates , followed by c. glabrata in 155 ( 27.7% ) , c. krusei in 28 ( 5.0% ) , c. kefyr in 20 ( 3.6% ) , and in 115 ( 20.5% ) representing several species of candida . the definitions of the clinical presentations of vvc for each group were as follows : avvc ( group 1 ) , currently asymptomatic women with initial or sporadic episodes of symptomatic vaginitis , that is , occurring fewer than four times per year ( n = 8) ; rvvc ( group 2 ) , symptomatic patients with a history of four or more clinical episodes of vvc per year ( n = 13 ) ; and controls ( group 3 ) , women who incidentally carried a normal level of c. krusei in their vaginal culture without vaginitis , who were completely asymptomatic and had no history of rvvc ( n = 7 ) . the control group included a mixed group of asymptomatic women who had no history of rvvc and women who had positive cultures . all participants took part in a short interview , which included questions regarding lifestyle and medical , gynecological , and sexual history . this study was reviewed and approved by the institutional review board at the university of ukurova , adana , turkey . the declaration of helsinki protocols were followed , and the patients provided written informed consent . the c. krusei isolates were recovered on chromagar candida ( becton dickinson , heidelberg , germany ) and appeared as dull , flat , light mauve to mauve , and colonies with a whitish border . the criteria for the identification of c. krusei were the absence of germ tube production in human serum at 37c at 2 hours , the production of abundant pseudohyphae with some moderate branching on cornmeal - tween 80 agar ( difco , detroit , mi , usa ) , and weak or absent urease activity . these isolates were verified by their assimilation patterns using the api 20c aux method ( biomrieux , marcy l'toile , france ) . c. krusei atcc 6258 was used as a positive control . antifungal testing was conducted at the department of microbiology , faculty of medicine , gazi university , ankara , using a broth microdilution method and according to the guidelines of the m27-a3 document of the clinical and laboratory standards institute ( clsi ) . before testing , each isolate was subcultured on sabouraud glucose agar ( sga ; merck , darmstadt , germany ) to ensure purity and viability . the interpretation of antifungal susceptibility was guided by criteria derived from the clsi 's m27-a3 protocol . the following antifungal agents were tested : amphotericin b ( 0.0316  g / ml ) , 5-flucytosine ( 0.0664 g / ml ) , caspofungin ( 0.0316  g / ml ) , fluconazole ( 0.12128  g / ml ) , itraconazole ( 0.0316  g / ml ) , voriconazole ( 0.00816  g / ml ) , econazole ( 0.0078  g / ml ) , ketoconazole ( 0.0078  g / ml ) , miconazole ( 0.0078  g / ml ) , and sulconazole ( 0.0316  g / ml ) . the minimal inhibitory concentrations ( mics ) were determined for each antifungal agent and used to classify the susceptibility of the isolates as follows : ( i ) amphotericin b , mic  1 ( g / ml ) , susceptible ( s ) ; ( ii ) 5-flucytosine , mic  4 ( g / ml ) s , mic between 8 and 16 ( g / ml ) intermediate ( i ) , mic  32 ( g / ml ) resistant ( r ) ; ( iii ) caspofungin , mic  2 ( g / ml ) r ; ( iv ) fluconazole , mic  8 ( g / ml ) s , mic between 16 and 32 ( g / ml ) susceptible dose dependent ( s - dd ) , mic  64 ( g / ml ) r ; ( v ) itraconazole , mic  0.125 ( g / ml ) s , mic between 0.25 and 0.5 ( g / ml ) s - dd , mic  1 ( g / ml ) r ; ( vi ) voriconazole ,  1 ( g / ml ) s , mic = 2 ( g / ml ) s - dd , mic  4 ( g / ml ) r ; ( vii ) ketoconazole , mic  16 ( g / ml ) r ; and ( viii ) miconazole , mic  4 ( g / ml ) r . currently , there are no published criteria for defining econazole and sulconazole susceptibility . these results were expressed in terms of the mic range and the mic50 , and mic90 values for each antifungal agent . all c. krusei isolates were declared resistant to fluconazole . c. krusei atcc 6258 and c. parapsilosis atcc 22019 were used as controls , as recommended by the clsi [ 12 , 14 ] . continuous variables , such as age and body mass index , were first divided into bins : < 30 , 3039 , 4049 , and > 50 years of age and < 25 ( under or normal weight ) and > 25 ( overweight or obese ) for body mass index . then , all categorical variables were cross classified by c. krusei infection or carrier status to descriptively summarize the association between the variables using the chi - squared test and to measure the degree of association using the odds ratio with a 95% confidence interval . for the multivariate analysis , logistic regression modeling of the binary data ( c. krusei infected , carrier , or neither ) was used to determine the significant predictors of c. krusei infection , after adjusting for other factors in the models . factors with significance levels < 0.30 were entered into the multivariate logistic model to determine the significant effect of each factor simultaneously on the prediction of c. krusei infection . c. krusei isolates were recovered from non pregnant patients without diabetes mellitus ( n = 9 ) , pregnant patients ( n = 6 ) , diabetes mellitus patients ( n = 6 ) , and contraceptive user 's ( n = 7 ) with no previous history of immunodeficiency who visited the faculty of medicine department of obstetrics and gynecology at ukurova university from 2009 until 2012 . of the c. krusei isolates , 24 ( 85.7% ) were the only species on plates and four ( 14.3% ) were part of mixed cultures , which were always included by c. albicans . in our group , 24 ( 85.7% ) women were in premenopausal and four ( 14.3% ) in postmenopausal period who had also exposed hormone replacement therapy . the mean age of the women was 40.3  10.4 years ( range , 21 to 59 years old ) . the basic demographic and clinical characteristics of women with vaginal c. krusei isolates are presented in tables 1 and 2 . perineal laceration is significantly higher ( p = 0.006 ) in the c. krusei group compared with the non - c . krusei group ( table 2 ) . as revealed by multivariate analysis , existence of perineal laceration ( p = 0.009 ) and an age of over 50 years ( p = 0.02 ) the mic results for the control strains of c. krusei atcc 6258 and c. parapsilosis atcc 22019 were within the acceptable range . all the c. krusei isolates were susceptible to amphotericin b , caspofungin , ketoconazole , and miconazole , and 10 of the 28 isolates ( 35.7% ) were defined as s - dd for 5-flucytosine . high mic rates were observed for fluconazole , of which 42.9% of the isolates were s - dd and 57.1% were r. remarkably , only 42.9% and 67.9% of the isolates were susceptible to itraconazole ( six s - dd and 10 r ) and voriconazole ( four s - dd and five r ) , respectively . the antifungal susceptibilities of c. krusei isolated from patients with avvc and rvvc did not differ significantly from those isolated from the group of women without symptoms of vaginitis ( p > 0.05 ; table 4 ) . to the best of our knowledge , this study is the largest series to exclusively investigate the prevalence of , host and risk factors for , and antifungal susceptibility of the minor isolate c. krusei . we also briefly summarized the baseline and demographic characteristics of women who had c. krusei present in their vaginal samples ( tables 1 and 2 ) . our data suggest that the prevalence of c. krusei is relatively high ( 5.0% ) in this population , displayed no specific host preferences , and was most often associated with rvvc . perineal laceration and increased age ( > 50 years ) were significant predictors of c. krusei vaginitis ( tables 2 and 3 ) . an important limitation of the present study is the lack of data regarding in vivo therapeutic drug choices and outcomes in c. krusei vaginitis . in addition , the number of women with c. krusei is very small , so , for some of the other factors we examined , the study may not have had sufficient power to detect a difference ( tables 13 ) . the presence of mixed cultures may affect the choice of treatment strategy . in our previous study , using chromogenic media , we determined that the percentage of mixed cultures recovered from vaginal samples was as high as 14.1% in adana , turkey . the results of this investigation ( 14.3% ) are similar to those of our earlier study . in addition , our finding that older women ( mean age , 40.3 years ) are more susceptible to infection corroborates the earlier finding of singh et al . ( mean age , 44 years ) . however , the women studied by singh et al .   all had rvvc , whereas our study included not only rvvc cases but also avvc and controls . these authors noted that c. krusei isolates were highly resistant to fluconazole ( mic90 > 64  g / ml ) , consistent with our findings . in addition , these authors reported resistance to miconazole ( mic90 > 4  g / ml ) , one of the most commonly used otc antifungal agents , which we did not observe . however , in line with our results , clotrimazole was observed to be the most active topical imidazole against c. krusei . moreover and more importantly , amphotericin b , caspofungin , itraconazole , and voriconazole were demonstrated to have favorable antifungal activity , although , in our study , several strains exhibited obvious high resistance to the latter two drugs . of note , the authors suggested that the therapy should continue for 26 weeks , regardless of the agent used . on the other hand , a recent study reported that fluconazole - resistant c. albicans appears to be emerging in clinics . therefore , antifungal susceptibility testing may assist in selecting the appropriate therapeutic drug not only for non - c . albicans candida vaginitis but also for rare fluconazole - resistant c. albicans vaginitis . in this investigation , amphotericin b , caspofungin , ketoconazole , and miconazole were observed to be active against all c. krusei isolates ( table 4 ) . in contrast to the findings of singh et al . , but in line with those of richter et al . , itraconazole exhibited high s - dd and r rates , 35.7% and 21.4% , respectively . although the new broad - spectrum oral antifungal voriconazole is rarely used in patients with vvc , we observed that 67.9% of the isolates were susceptible to voriconazole . pfaller et al .   reported a higher rate , stating that 81.5% of 426 genital c. krusei isolates were susceptible to voriconazole using the clsi m44-a disk diffusion method . in conrast to our findings , lyon et al .   reported that fluconazole resistance rates were highly predictive of resistance to voriconazole . although specific clinical cutoff points have not yet been assigned for econazole and sulconazole susceptibility , we observed low mic values for both drugs . this study is the largest to date to investigate the antifungal drug - resistance profile of c. krusei vaginal isolates and the epidemiologic risk factors of infection . in this investigation , perineal laceration and increasing age ( > 50 years ) were important predictive factors for c. krusei vaginitis or carrier status ( table 3 ) . this study also revealed that the topical imidazoles ( ketoconazole and miconazole ) , which can be prescribed safely in routine practice , were effective against all c. krusei isolates . in addition , the vaginal c. krusei isolates were less susceptible to itraconazole ( 42.9% ) and voriconazole ( 67.9% ) than to other antifungal therapeutics . these findings may have implications for the in vivo therapeutic treatment of c. krusei vaginitis ( table 4 ) . thus , the identification of c. krusei in vaginal samples and in vitro antifungal testing will assist in the selection of appropriate antifungal agents and therapy duration . future clinical trials to determine the in vivo efficacy of the current drugs for women with c. krusei vaginitis are required .
objective . 
 candida krusei causes approximately 1% of vulvovaginal candidiasis ( vvc ) cases and is naturally resistant to fluconazole . 
 antifungal testing may be required if c. krusei vaginitis fails to respond to non - fluconazole therapy , particularly in patients with recurrent infections . 
 design . 
 we investigated the clinical characteristics and antifungal susceptibility profile of vaginal c. krusei isolates . between 2009 and 2012 , we identified 560 unrelated candida spp .- positive vaginal cultures , of which 28 ( 5.0% ) were c. krusei . 
 these isolates were analyzed according to host factors and the clinical forms of vvc , and their in vitro susceptibility to 10 antifungal agents was tested using a reference microdilution method . results . 
 we observed that perineal laceration and increased age ( > 50 years ) were significant predictors of c. krusei in vaginal samples ( p < 0.05 ) . 
 all isolates were susceptible to amphotericin b , caspofungin , ketoconazole , and miconazole . additionally , susceptible dose - dependent and resistant rates were found for fluconazole as 42.9% and 57.1% , respectively . remarkably , only 42.9% and 67.9% of the isolates were susceptible to itraconazole and voriconazole , respectively . 
 conclusions . understanding local susceptibility patterns , especially those of non - c . 
 albicans candida species , can significantly aid in the selection of an effective antifungal agent . 
 the in vivo response of c. krusei vaginitis to various antifungal therapeutics remains unknown and requires further research .