CIinicaI significance of isoIated biIiary candidiasis in patients with unresectabIe choIangiocarcinoma

In-Ho Kim， Jae-Ki Choi， Dong-Gun Lee， In Seok Lee， Tae Ho Hong， Young Kyoung You，Ho Jong Chun and Myung Ah Lee

Seoul， Korea

CIinicaI significance of isoIated biIiary candidiasis in patients with unresectabIe choIangiocarcinoma

In-Ho Kim， Jae-Ki Choi， Dong-Gun Lee， In Seok Lee， Tae Ho Hong， Young Kyoung You，Ho Jong Chun and Myung Ah Lee

Seoul， Korea

BACKGROUND： The frequency of isolated biliary candidiasis is increasing in cancer patients. The clinical significance of isolated biliary candidiasis remains unclear. We analyzed the risk factors of biliary candidiasis and outcomes of the patients with unresectable cholangiocarcinoma after percutaneous transhepatic biliary drainage （PTBD）.

METHODS： Among 430 patients who underwent PTBD between January 2012 and March 2015， 121 patients had unresectable cholangiocarcinoma. Bile and blood samples were collected for consecutive fungal culture.

RESULTS： The study cohort included 49 women and 72 men with a median age of 71 years. Multivariate analysis showed that cancer progression （P=0.013）， concurrent presence of another microorganism （P=0.010）， and previous long-term（＞7 days） antibiotic use （P=0.011） were potential risk factors of biliary candidiasis. Chemotherapy was not associated with overall biliary candidiasis （P=0.196）， but was significantly related to repeated biliary candidiasis （P=0.011）. Patients with isolated biliary candidiasis showed remarkably reduced survival compared with those without ［median overall survival （OS）： 32 vs 62 days， P=0.011］. Subgroup analysis was also performed. Patients with repeated candidiasis had markedly decreased survival compared with those with transient candidiasis （median OS： 30 vs 49 days， P=0.046）. Biliary candidiasis was identified as a poor prognostic factor by univariate and multivariate analyses （P=0.033）. Four cases of repeated candidiasis （4/19， 21%） showed Candida species in consecutive blood culture until the end of the study， but others showed no candidemia.

CONCLUSIONS： Isolated biliary candidiasis may be associated with poor prognosis in patients with unresectable cholangiocarcinoma. Especially， repeated biliary candidiasis may have the possibility of progression to candidemia. We suggest that biliary dilatation treatment or antifungal agents might be helpful for patients with biliary candidiasis.

（Hepatobiliary Pancreat Dis Int 2016；15：533-539）

biliary candidiasis；

biliary obstruction；

cholangiocarcinoma；

percutaneous transhepatic biliary drainage

Introduction

Malignant biliary obstruction is a common complication in patients with biliary tract cancer and a potential risk factor for poor outcomes.［1］Since malignant biliary obstruction may cause cholangitis or sepsis， oncologists should consider this situation as an oncologic emergency.［2］Currently， many clinicians perform interventional procedures， such as endoscopic retrograde cholangiopancreatography （ERCP） and percutaneous transhepatic biliary drainage （PTBD）， to restore adequate bile duct drainage. Moreover， active treatment with antimicrobial agents， based on bile culture and antimicrobial susceptibility data， often improves clinical outcomes.［3］Although it is debated whetherPTBD is superior to other procedures for the decompression of bile duct obstruction，［4］PTBD is useful when endoscopic procedures are not possible， especially in patients with hilar obstruction or surgically altered anatomy.［5］Additionally， since bile samples from PTBD are less prone to contamination by intestinal microorganisms than those obtained from ERCP， the results of bile culture using PTBD samples are more reliable for decisionmaking regarding the selection of antimicrobial agents.［6］

The prevalence of fungal infection of the biliary tract，such as infection due to Candida species， is increasing and significant in immunocompromised patients.［7］Candida infection is frequently noted in cases of highgrade biliary strictures or tumor stenosis.［8］The term“biliary candidiasis” refers to a condition in which Candida species are detected in the bile； this condition is an unrecognized clinical problem， particularly in isolated biliary candidiasis， in which Candida species are detected only in the bile but not in the blood. Although the reported mortality rate for candidemia is very high，［9］the association between isolated biliary candidiasis and survival rates is not well known. The present study aimed to analyze clinical risk factors of initially isolated biliary candidiasis. We also investigated the association between isolated biliary candidiasis and clinical outcomes among primary unresectable cholangiocarcinoma patients with biliary obstruction.

Methods

Patients

We reviewed the medical records of 430 patients who had undergone PTBD at our center between January 2012 and March 2015 and identified 296 patients with malignant biliary obstruction and 134 with nonmalignant disease. Of the 296 patients with malignant biliary obstruction， 132 had biliary tract cancer and 122 had blood and bile culture at least twice. Candida species were isolated from both blood and bile in one case at the beginning of the enrollment which indicated candidemia. This case was excluded from further analysis. A total of 121 patients were analyzed in the present study. Fig. 1 shows the schematic flow of the patient enrollment.

Microbiological analysis and antibiotic therapy

All bile and blood samples were obtained immediately after PTBD. The follow-up culture of bile and blood was performed every 7±2 days after initial culture. Aliquots of all bile and blood samples were placed in sterile tubes and delivered to the microbiology laboratory within 2 hours. The samples were cultured using an automated culture system （BACTEC FX； Becton Dickinson， EastRutherford， NJ， USA）. Bacterial identification was performed using the VITEK2 automated system （bioMerieux，Hazelwood， MO， USA）. The cultures were incubated for 48 hours， with the first reading at 24 hours. Biliary candidiasis cases were divided into two groups： transient or repeated. Transient candidiasis cases were defined as those with one bile culture positive for Candida species， followed by consecutive negative bile cultures until the end of the study. Repeated candidiasis cases were defined as those with two or more bile culture positives for Candida species during the study period. Antibiotic treatment was given when the patient had fever （body temperature＞38 ℃）， leukocytosis （＞12×109/L）， or C-reactive protein levels ＞1 mg/dL， or signs of systemic inflammatory response or shock （blood pressure ＜90/50 mmHg） were observed. Since there are no guidelines for the treatment of isolated biliary candidiasis， antifungal treatment was based on the patients' symptoms and clinicians' judgment.

Fig. 1. Schematic representation of the study design. PTBD： percutaneous transhepatic biliary drainage.

Statistical analysis

Continuous variables were expressed as mean and standard deviation. Categorical variables were presented as the total and percentage. The Chi-square or Fisher' s exact test was used to compare categorical variables，whereas Student's t test was used to compare continuous variables. Laboratory parameters were analyzed using the Wilcoxon-Mann-Whitney test. Logistic regression was used for univariate and multivariate analysis of possible risk factors for isolated biliary candidiasis. The effect of antifungal agent on survival and negative conversion of Candida species was analyzed by logistic regression. Post-PTBD overall survival （pOS） was calculated from thedate of PTBD to the date of death. Patients who were alive at the end of the study were treated as censored at their last follow-up for the analysis of pOS. Univariate analyses for pOS were performed using the Kaplan-Meier method， followed by the log-rank test， and multivariate Cox regression models were used to verify the prognostic effects of isolated biliary candidiasis on survival rates after adjusting for baseline factors and potential prognostic factors， including age， gender， cancer progression， concurrent presence of another microorganism，previous long-term antibiotic use （＞7 days）， and recent chemotherapy （within one month）. A two-tailed P value of ＜0.05 was considered statistically significant. SPSS for Windows v. 22.0 （SPSS Inc.， Chicago， IL， USA） was used to perform all analyses and to create graphs.

Results

Patient characteristics

Table 1 lists the baseline characteristics of our patients. Their median age was 71 years （range 38-95）. We classified the patients according to the types of jaundice that resulted in the need of PTBD： obstructive jaundice due to cancer progression （n=71）， initial diagnosis of a cancer （n=37）， and other causes such as transient aggravation of cholangitis （n=13）.

Candida species were found in 28 of the 121 （23%）patients. Candida albicans was the most common species （12 patients， 43%）. Mixed growth of two different Candida species was noted in six patients （Table 2）. Repeated candidiasis was noted in 19 （68%） patients，whereas transient candidiasis was observed in nine （32%）. Among biliary candidiasis patients， seven were treated with antifungal agents， including four with fluconazole and three with amphotericin B. And three patients received biliary dilatation therapy （biliary stent insertion）.

Analysis for the presence of other microorganisms revealed the presence of microorganisms other than Candida in 58 patients. Furthermore， patients in whom more than one species were isolated were commonly seen （Table 2）. The mean number of microorganisms was 1.05±1.26， and more microorganisms were found in patients with biliary candidiasis than in those without（1.68±1.31 vs 0.86±1.19； P=0.002）.

Cancer progression （P=0.016）， the presence of another microorganism （P=0.005）， and previous long-term antibiotic use （P＜0.001） were more frequent in patients with biliary candidiasis than in those without.

Risk factors for biliary candidiasis in patients with malignant biliary obstruction

By univariate and multivariate analyses （Table 3），cancer progression （hazard ratio ［HR］=4.226； 95% confidence interval ［CI］： 1.356-13.175； P=0.013）， concurrent presence of another microorganism （HR=3.877； 95% CI：1.385-10.848； P=0.010）， and previous long-term antibiotic use （＞7 days） （HR=4.647； 95% CI： 1.416-15.244； P=0.011）were identified as potential risk factors for isolated biliary candidiasis among patients with primary cholangiocarcinoma. Recent systemic chemotherapy （within 1 month）was not a risk factor of biliary candidiasis （P=0.196）.

Table 1. Baseline characteristics

Table 2. Candida species and other concurrent microorganism

We further evaluated risk factors by subgroup analysis of patients with repeated versus transient biliary candidiasis. In the repeated candidiasis group， cancer progression， concurrent presence of another microorganism，and previous long-term antibiotic use （＞7 days） were risk factors for biliary candidiasis. Additionally， recent systemic chemotherapy （＜1 month） （HR=5.295； 95% CI：1.474-19.021； P=0.011）， which was not a risk factor in the analysis for all biliary candidiasis cases， was found to be a risk factor for repeated candidiasis （Table 4）. However， these were not significant risk factors in patients with transient candidiasis.

Association between isolated biliary candidiasis and survival outcome

The median follow-up period for survival analysis was 47 days. By the end of the study period， 92 （76%）patients died. Twenty-three of 28 （82%） isolated biliary candidiasis patients died， 18 of 19 （95%） repeated candidiasis patients and 5 of 9 （56%） patients died. Patients with isolated biliary candidiasis had significantly shorter pOS compared with those without isolated biliary candidiasis （median： 32 vs 62 days， P=0.011， Fig. 2A）. Patients with repeated candidiasis had worse pOS compared with those without candidiasis or transient candidiasis（Fig. 2B and C）. There was no significant difference in the survival time between the patients with transient biliary candidiasis and those without （median： 49 vs 62 days，P=0.722， Fig. 2D）.

Table 5 shows the results of the Cox proportional hazard model for post-PTBD survival time. In the uni-variate analysis， cancer progression （HR=1.893； 95% CI：1.205-2.972； P=0.006， and isolated biliary candidiasis（HR=1.859； 95% CI： 1.150-3.006； P=0.011） were associated with poor pOS. Additionally， multivariate analysis revealed that cancer progression （HR=1.802； 95% CI：1.131-2.873； P=0.013） and isolated biliary candidiasis（HR=1.778； 95% CI： 1.047-3.018； P=0.033） were important prognostic factors for pOS. Treatment with antifungal agents neither offered any benefit with respect to the negative conversion of Candida species （HR=0.800； 95% CI： 0.123-5.212； P=0.815） nor prolonged pOS in 28 patients with isolated biliary candidiasis （HR=1.186； 95% CI： 0.463-3.038； P=0.723）. All patients （n=3） who receiving bile duct dilatation treatment achieved negative conversion. Among the patients with repeated biliary candidiasis， 4 （4/19， 21%） showed Candida positive in bloodculture at the end of the follow-up. None of the patients with transient biliary candidiasis showed candidemia.

Table 3. Risk factors for isolated biliary candidiasis

Table 4. Risk factors for repeated biliary candidiasis

Fig. 2. Post-PTBD overall survival （pOS） and isolated biliary candidiasis （n=121）. A： Patients with isolated biliary candidiasis showed remarkably reduced pOS compared with those without biliary candidiasis （median 32 vs 62 days， P=0.011）； B： Patients with repeated candidiasis also markedly decreased pOS compared with those without biliary candidiasis （median 30 vs 62 days， P＜0.001）； C： Patients with repeated candidiasis indicated remarkable reduced pOS than those with transient candidiasis （median 30 vs 49 days， P=0.046）；D： Transient biliary candidiasis did not show statistically significant difference in pOS compared to patients without biliary candidiasis（median 49 vs 62 days， P=0.722）. PTBD： percutaneous transhepatic biliary drainage.

Table 5. Cox proportional hazards model for post-PTBD survival time according to isolated biliary candidiasis

Discussion

According to a previous prospective surveillance study in 2004，［10］Candida species were the fourth most common cause of nosocomial bloodstream infections in the United States' hospitals from 1995 to 2002. Moreover， a report of the national nosocomial infections surveillance system revealed that the percentage of nosocomial urinary-tract infections due to Candida species increased from 22%（1986-1989） to almost 40% （1992-1997）， indicating that candidiasis may be an increasingly important nosocomial issue.［11］Similarly， in the last several years， the number of patients with biliary candidiasis from various causes has increased.［12-16］In particular， a previous study［6］reported that biliary fungal infection in cancer patients exhibited different characteristics compared with those with biliary obstruction due to benign diseases. Others suggested that an immunocompromised state， such as that in cases of cancer or prior long-term antibiotic use， is associated with biliary candidiasis.［8，17］Diebel and coworkers did not find candidemia in patients with biliary Candida infection.［18］Furthermore， Candida species have little inherent virulence， as illustrated by their ability to exist in a commensal relationship with human beings and animals.［19］

Owing to the increasing frequency of Candida infection， we frequently encounter isolated biliary candidiasis in cancer patients who have undergone PTBD. However，the clinical significance of isolated biliary candidiasis remains unclear， and the association between isolated biliary candidiasis and survival outcomes is unknown. To our knowledge， this is the first study on isolated biliary candidiasis and survival rates in cancer patients.

The present study showed that Candida albicans was isolated as the most common species of Candida. In addition， 21% （6/28） of patients harbored two different species of Candida. Moreover， concurrent bacteria were also presented as the most common type microorganism in mixed infections when more than two different strains were identified. This type of complexity is rarely found in benign biliary obstruction.［20］This is probably because patients with malignant biliary obstruction are immunocompromised. Therefore， it is likely that antifungal drugs are required for treating patients with malignant biliary obstruction， but further research is necessary to confirm this.

Similar to those from previous studies， our results indicated that previous long-term use （＞7 days） of antibiotics and cancer progression may have a relation with increased frequency of isolated biliary candidiasis.［8，17，21］In addition， concurrent microorganisms， such as bacteria are frequently identified in patients with biliary candidiasis. The long-term use of antibiotics may cause the proliferation of not only Candida， but also drugresistant bacteria.［22］However， these findings should not be translated as an intention to discontinue antibiotics promptly because malignant biliary obstruction is often accompanied by cholangitis or sepsis.［2］We insisted that proper antibiotics according to individual medical condition is clearly helpful. However， unnecessary long-term antibiotic usage may result in the proliferation of Candida as well as other bacteria. Therefore， there is a need for a well-designed standard to which clinicians can refer for the initiation and discontinuation of antibiotic treatment in patients with malignant biliary obstruction.

Although chemotherapy was not a risk factor of biliary candidiasis， it was a risk factor of repeated biliary candidiasis in our subgroup analysis. Candida species may proliferate temporarily when the patients are in the immunosuppressed state as a consequence of chemotherapy and disappear when the immune status is improved. However， repeated chemotherapy increases the duration of the immunosuppressed state， leading to repeated candidiasis. This indicates that the risk of fungal infection， such as candidiasis， is of clinical significance in patients who have been receiving chemotherapy for a long duration. Therefore， in patients undergoing repeated chemotherapy， clinicians should consider the possibility of biliary Candida infection.

Our results showed that isolated biliary candidiasis is associated with cancer progression， which induces deterioration of the biliary stricture and results in a poor prognosis in patients with advanced cholangiocarcinoma，especially in those with repeated candidiasis. These results are consistent with those of a previous study［23］showing that the degree of bile duct stenosis is associated with biliary candidiasis， which in turn results in poor prognosis. Malignant biliary obstruction leads to impaired biliary clearance and the inability to clear the Candida species，［24］thus suggestsing that dilatation treatment for stenosis may improve prognosis in patients with biliary obstruction. In fact， 3 patients in the present study were treated with bile duct dilatation （biliary stent） and they were all free from biliary candidiasis. A large， well-designed， prospective study is needed to validate our results.

It should further be considered whether antifungal agents are useful in these patients. In our study， patients with repeated biliary candidiasis had a poorer prognosis and more frequent candidemia than those with transient candidiasis. We therefore suggest that antifungal agents should be considered in patients with repeated biliary candidiasis and uncontrolled cholangitis.

Our study has certain limitations. First， we couldnot investigate the sensitivity of Candida species to antifungal agents because of the retrospective nature of the study. Therefore， we could not determine whether the antifungal agent administered was the appropriate treatment in the present study. Another limitation is the sample size， our results should be interpreted with caution.

In conclusion， isolated biliary candidiasis is a frequent comorbidity in patients with malignant biliary obstruction； it is associated with a poor prognosis in patients with advanced cholangiocarcinoma. Moreover， positive fungal cultures of bile fluid should not be ignored as mere contamination artifacts； rather， these findings should be considered when predicting poor prognosis and deciding on dilatation treatment or antifungal agents for cases of repeated biliary candidiasis and uncontrolled cholangitis.

Acknowledgements： We would like to thank all members of Department of Hepato-Biliary-Pancreatic Cancer Center， Seoul St. Mary's Hospital， The Catholic University of Korea College of Medicine， Seoul， Korea.

Contributors： KIH and LMA proposed the study. KIH， LIS， HTH，YYK， CHJ and LMA collected the data. KIH， CJK， LDG and LMA analyzed the data. KIH and LMA drafted the manuscript. LMA is the guarantor.

Funding： None.

Ethical approval： The present study was approved by the Institutional Review Board of the Seoul St. Mary's Hospital of the Catholic University of Korea， and informed consent was obtained from all participants.

Competing interest： No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

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November 27， 2015

Accepted after revision April 6， 2016

Author Affiliations： Departments of Internal Medicine， Division of Medical Oncology （Kim IH and Lee MA）， Division of Infectious Diseases（Lee DG）， Division of Gastroenterology （Lee IS）， Department of Surgery（Hong TH and You YK）， Department of Radiology （Chun HJ）， and Department of Hepato-Biliary-Pancreatic Cancer Center （Lee IS， Hong TH，You YK， Chun HJ and Lee MA）， Seoul St. Mary's Hospital， The Catholic University of Korea， Seoul， Korea； Departments of Internal Medicine， Division of Infectious Diseases， Bucheon St. Mary's Hospital， The Catholic University of Korea， Seoul， Korea （Choi JK）

Myung Ah Lee， MD， PhD， Department of Internal Medicine， Seoul St. Mary's Hospital， The Catholic University of Korea College of Medicine， 222 Banpo-daero， Seocho-gu， Seoul 137-701， Korea （Tel：+82-2-2258-6044； Fax： +82-2-599-3589； Email： angelamd@catholic.ac.kr）? 2016， Hepatobiliary Pancreat Dis Int. All rights reserved.

10.1016/S1499-3872（16）60109-1

Published online June 14， 2016.