Date Published: March 7, 2019
Publisher: Public Library of Science
Author(s): Ziauddin Khan, Suhail Ahmad, Noura Al-Sweih, Seema Khan, Leena Joseph, David D. Roberts.
Candida lusitaniae is an opportunistic yeast pathogen in certain high-risk patient populations/cohorts. The species exhibits an unusual antifungal susceptibility profile with tendency to acquire rapid resistance. Here, we describe prevalence of C. lusitaniae in clinical specimens in Kuwait, its antifungal susceptibility profile and role in neonatal fungemia.
Clinical C. lusitaniae isolates recovered from diverse specimens during 2011 to 2017 were retrospectively analyzed. All isolates were identified by germ tube test, growth on CHROMagar Candida and by Vitek 2 yeast identification system. A simple species-specific PCR assay was developed and results were confirmed by PCR-sequencing of ITS region of rDNA. Antifungal susceptibility was determined by Etest. Minimum inhibitory concentrations (MICs) were recorded after 24 h incubation at 35°C.
Of 7068 yeast isolates, 134 (1.89%) were identified as C. lusitaniae including 25 (2.52%) among 990 bloodstream isolates. Species-specific PCR and PCR-sequencing of rDNA confirmed identification. Of 11 cases of neonatal candidemia, 9 occurred in NICU of Hospital A and are described here. Eight of 9 neonates received liposomal amphotericin B, which was followed by fluconazole in 7 and additionally by caspofungin in 2 cases as salvage therapy. Three of 8 (37.5%) patients died. No isolate exhibited reduced susceptibility to amphotericin B, fluconazole, voriconazole, caspopfungin, micafungin and anidulafungin. The MIC ± geometric mean values for amphotericin B, fluconazole, voriconazole, and caspofungin were as follows: 0.072 ± 0.037 μg/ml, 2.32 ± 0.49 μg/ml, 0.09 ± 0.01 μg/ml and 0.16 ± 0.08 μg/ml, respectively. Only two isolates exhibited reduced susceptibility to fluconazole.
This study describes the prevalence and antifungal susceptibility profile of clinical C. lusitaniae isolates in Kuwait. No isolate showed reduced susceptibility to amphotericin B. The study highlights the emerging role of C. lusitaniae as a healthcare-associated pathogen capable of causing fungemia in preterm neonates and causing significant mortality.
Candida lusitaniae (teleomorph Clavispora lusitaniae) was first described by van Uden and Carmo-Sousa as a common flora in the gastrointestinal tract of warm blooded animals . It was recognized as a human pathogen in three patients with septicemia and in two of them, the isolates were reported as variants of C. tropicalis [2, 3]. The first documented case of opportunistic infection where C. lusitaniae strain developed resistance to amphotericin B during therapy was published in 1979 [4,5]. Over the years, there has been a gradual increase in the number of cases with C. lusitaniae infection, predominantly in cancer patients who received bone marrow transplantation or cytotoxic chemotherapy [6,7]. Some strains are known to exhibit intrinsic or acquired resistance to amphotericin B [5, 8–11]. This species is being increasingly isolated from cancer patients on empirical/prophylaxis antifungal therapy [12, 13]. A study from Anderson Cancer Center (Houston, Texas) during 2006–2013 revealed a high rate of occurrence of C. lusitaniae among cancer patients (1.45 episodes/100,000 inpatient days) and it was also the third most common cause of breakthrough candidemia (7/37, 19%) associated with 53% mortality . In Kuwait, little information is available on the association of C. lusitaniae with human colonization and infection . This study describes prevalence and susceptibility profile of clinical isolates of C. lusitaniae and its role in neonatal fungemia in Kuwait.
In this study, we describe the prevalence of C. lusitaniae in clinical yeast species and its role in neonatal fungemia in Kuwait. For rapid and unambiguous identification, a simple, low-cost (~1 US$ per sample excluding the cost of culture and personnel time) C. lusitaniae-specific PCR assay was developed which could be completed within 4 hours using basic PCR and gel electrophoresis equipment that are readily available in routine mycology laboratories.