Introducción: La candidemia se convirtió en una infección importante del torrente sanguíneo que se asocia frecuentemente con índices elevados de mortalidad y morbilidad. Las especies de Candida generan del 70% al 80% de las infecciones micóticas invasivas del torrente sanguíneo y son la cuarta causa más frecuente de infecciones hospitalarias del torrente sanguíneo. La identificación de las especies de Candida es importante, ya que las especies no albicans son cada vez más numerosas y resistentes a las drogas antimicóticas. El objetivo del estudio fue aislar e identificar diferentes especies de Candida asociadas con candidemia y analizar su patrón de susceptibilidad a los antimicóticos. Materiales y métodos: Los pacientes con sospecha de infecciones del torrente sanguíneo (ITS) fueron reclutados durante un período de un año para el estudio prospectivo. Se analizaron las características demográficas, la duración de la internación y los factores de riesgo asociados y la evolución clínica. El análisis de las muestras de sangre tuvo lugar mediante el sistema automatizado BacTAlert. La identificación y la susceptibilidad antimicótica de las levaduras fueron realizadas mediante el uso de dispositivo VITEK-2. Resultados: Las especies de Candida fueron aisladas en 30 de los 3146 cultivos recibidos (0.9%). La mayoría de los casos de candidemia tuvieron lugar en hombres (66%). Los factores de riesgo más frecuentes fueron el uso de antibióticos de amplio espectro, la vía central y la ventilación mecánica. Entre las levaduras aisladas, las especies de >i>Candida no albicans fueron predominantes (60%), en comparación con la especie C. albicans (40%). La especie albicans presentó una susceptibilidad del 100% a los azoles y la anfotericina, en tanto que las especies no albicans fueron resistentes. De los 30 pacientes mencionados, 5 fallecieron. Conclusión: La prevalencia de Candida no albicans fue mayor en comparación con la prevalencia de Candida albicans. Las especies no albicans fueron más resistentes a los antimicóticos. En consecuencia, los pacientes internados deberían ser evaluados para identificar la candidemia.

Introduction

Blood stream infections (BSI) caused by various Candida species have been reported from many countries worldwide and are a significant cause of morbidity and mortality in hospitalized patients. Candida bloodstream infections constitute the vast majority of nosocomial fungal infections. Candida species are the fourth most common cause of bloodstream infections and are the leading cause of invasive fungal infections among hospitalized patients.^{1 2} Candidemia is a life threatening fungal infection associated with a mortality rate of 38%. It also prolongs hospital stays by as much as 30 days and increases the cost of medical care.³ Several retrospective studies have demonstrated that a number of predisposing factors are responsible for spread of Candida infections in the intensive care unit (ICU).^{4 6} The frequent use of antibiotics, central venous catheters and other invasive devices, abdominal surgery and prolonged stay in the ICU puts patients at a high risk of infection with candida.⁷ Candida BSIs are a well-recognized cause of morbidity and mortality among the critically ill. Though the crude mortality varies between studies, most authors report high percentages (39%-60%) and excess financial burden.^{8 9}

More than 90% of the invasive infections due to Candida are attributed to five species: C. albicans, C. glabrata, C. parapsilosis, C. tropicalis and C. krusei. However, the list of new species of Candida isolated from clinical specimens continues to grow every year.⁵ This is due to the fact that clinical microbiology laboratories worldwide are using commercially available identification methods to supplement the conventional methods of identification. C. albicans has been the most common species of candida isolated from BSI worldwide. A number of surveillance programs in the 1990s gave the percentage prevalence of C. albicans as ranging from 50% (in the SENTRY surveillance program 1997-2000) to as much as 71% (Fungal Disease Registry, Canada 1992-1994).¹⁰ Historically, C. albicans is the most common cause of candidemia worldwide. However, in recent years, some studies have reported an increase of candidemia due to non-albicans Candida species, with the threat of increased mortality and antifungal drug resistance.^{11 12} The intrinsic and emerging resistance to azoles actually represents a major challenge for empirical therapeutic and prophylactic strategies.¹³

With the emergence of non-albicans species of Candida worldwide, especially C. glabrata and C. krusei, antifungal drug resistance has become a major cause of concern in the management of candidemia. Resistance to fluconazole and other triazoles is very high among these species of Candida.⁵ Other non-albicans Candida species like C. tropicalis and C. parapsilosis have been found to have variable susceptibility pattern to the azole group of drugs. There have been a few reports of Candida species being resistant to amphotericin B and echinocandins also.¹⁴

The increasing incidence of candidemia due to non-albicans species and emergence of antifungal resistance necessitates the formulation of empirical therapy for treatment of patients suffering from candidemia and antifungal prophylaxis for patients at risk of developing the infection.^{15 16}

Early and prompt diagnosis, proper treatment and prevention of candidemia pose a major challenge for microbiologists and clinicians worldwide. The knowledge of current prevalent strain and their drug resistance profile are key determinants in the selection of appropriate antifungal prophylaxis and empirical therapy. Therefore, the study was conducted to determine the current prevalence of candidemia among patients admitted to ICU and antifungal resistance profile of the isolates.

Materials and methods

During one year prospective study (June 2014-May 2015) at Dayanand Medical College & Hospital, suspected patients of BSI admitted in various intensive care units were enrolled. Patient's demographic details such as age, sex, duration of hospital stay, associated risk factors such as CVC, mechanical ventilation,steroid therapy, total parenteral nuitrition, immunocompromised conditions like diabetes, malignancy etc and outcome were studied.

Blood samples were collected from patients after all aseptic precautions. Blood and body fluid culture was done by Bac-T alert and Bactec automated systems. The blood culture bottles were incubated till the bottle flagged positive by the system or for a maximum period of 7 days. Broth from positive bottles was smeared and Gram-stained, and sub-cultured on Sabouraud's dextrose agar (SDA) medium and incubated aerobically at 37 °C for 24-48 hours. Candida isolates, characterized by smooth, creamy and pasty appearance of colonies on SDA, were subjected to speciation by Germ tube test, sugar fermentation test. An episode of candidemia was identified when the candida was isolated from the blood culture of the patient. Yeast identification was done by YST cards which were processed by VITEK-2 instrument antifungal susceptibility testing of yeasts was done as per CLSI guidelines using YST-AST cards which contained amphoptericin B, fluconazole, voriconazole, caspofungin and flucytosine.¹⁷ Data was analyzed for statistical significance between various sub-groups using Z-test of proportion. P value < 0.05 was taken as statistically significant. Ethical clearance was taken from Institutional Ethics Committee.

Results

Out of 3146 blood cultures received in our laboratory during the study period, Candida species were isolated in 30 (0.9%) blood cultures. Out of 30 candidemia cases, 66% were males and 34% were females. Age of patients having candidemia ranged from 19 years to 88 years with a mean of 51.6 years (Figure 1).

The length of ICU stay ranged from 4 days to 92 days with a mean of 22.8 days. The most common risk factors were urinary catheterization (90%), use of broad spectrum antibiotics (90%), central line (70%) and mechanical ventilation (46.7%). Out of 30 candidaemia cases, 22 were primary candidaemia whearas 8 had concomitant candiduria (6 cases) and soft tissue infection (2). Among the yeast isolates, non albicans Candida species were predominant (60%) compared to C. albicans (40%). Among non albicans, C. tropicalis was commonest followed by C. parapsilosis (Figure 2). Candida isolates showed resistance to fluconazole (13.8%) and 3.4% resistace to each voriconazole, caspofungin and amphotericin B but all isolates were susceptible to flucytosine (Table 1).

Candida albicans showed 100% susceptibility to voriconazole, fluconazole, amphotericin whereas non albicans Candida species showed resistance to fluconazole (23.6%), voriconazole (5.6%) and amphotericin (5.6%). Among non albicans Candida isolates, C. glabrata, C. krusei, C. guilliermondii and C. lusitaniae showed no resistance to antifungals tested. Candida albicans showed resistance to caspofungin (8.4%) as compared to non albicans Candida species. Non albicans Candida showed higher resistance and it was nearly significant stastically to fluconazole and amphotericin B (Table 2). Out of these 30 patients, 25 patients were discharged in satisfactory condition while 5 patients expired (16.6%).

Discussion

The prevalence of candida species in BSI of ICU patients was 0.9% similar to reported by Giri et al. (0.65%),¹⁸ however a higher prevalence of 6%,¹⁹ 16%,²⁰ 18%²¹ was observed by various authors.

In our study, the age of patients with candidemia ranged from 19 to 88 years, with mean age of 51.6 years. Similar findings have been reported in studies by Leon et al. who reported a mean age of 60 years and Laupland et al. who reported a mean age of 57.8 years in their 5-year study of invasive Candida infections.^{22 23} Male patients outnumbered females in our study with a male to female ratio of 2:1. Results were consistent with various studies which reported male preponderance.^{22 24 25} The most common risk factors associated with candidemia were urinary catheterization (90%), use of broad spectrum antibiotics (90%), central line (70%) and mechanical ventilation (46.7%) similar to reported in literature¹⁸ where long term antibiotic therapy (64.1%) use of CVCs (56.4%), urinary catheters (53.9%) were common risk factors.

In our study higher percentage of non- albicans Candida (60%) was observed, in contrast C. albicans was predominant in various studies (50%, 53%, 64.3%).^{20 26 27}