Multimodal acquisition of Candida tropicalis responsible for candidemia in a neonatal intensive care unit
Shamanth A.S, Shivaprakash M.R, Jayashree M, L.N. Yeddanapudi, K.L.N. Rao, Arunaloke Chakrabarti
Objectives: 
Candida tropicalis is the predominant agent causing candidemia in Indian intensive care units (ICUs). Irrespective of low drug resistance among C. tropicalis isolates, incidence of candidemia due to this agent is high compared to other drug resistant candida species. Candida species colonization is considered as an independent risk factor for invasive candidiasis. Therefore, we evaluated the role of candida colonization, environmental burden and hand carriage of health care workers (HCWs) for the development of C. tropicalis candidemia in neonatal ICU.
Methods:
A total of 108 patients admitted to the neonatal ICU were screened for candida colonization. Oral, rectal and skin (armpit, neck and forehead) swabs were collected every day from the admission day to patients discharge or development of C. tropicalis candidemia. The samples were inoculated on to Sabouraud dextrose agar (SDA) and growth of any candida species was identified by Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) assay. A total of 39 neonatal ICU’s environmental sites and 57 hand washings of HCWs posted in that area were sampled. Clonal origin of the C. tropicalis isolates obtained via colonization sites, environmental sites and hands of HCWs was evaluated by amplified fragment length polymorphism (AFLP).
Results:
Of the 108 patients 21(19.4%) patients developed candidemia. Seven (33.3%) patients developed C. tropicalis candidemia, followed by C. pelliculosa (5, 23.8%), C. utilis (4, 19%), C. parapsilosis (3, 14.2%) C. albicans and C. krusei (1, 4.7%). All the patients who developed C. tropicalis candidemia were previously colonized with C. tropicalis at least in one of the sites checked. On the day of admission 63 (58.3%), 77 (71.2%) and 11 (10.1%) patients were colonized by different Candida species in oral, rectal and skin sites respectively. Of these colonized patients C. tropicalis was colonized in only 6 (5.55%) patients at oral and rectal site and only 1 (0.92%) patient at skin site. Eventually all the patients were colonized by different Candida species in oral and rectal sites during their hospital stay and only 28 (25.9%) patients had skin colonization. Majority of the colonized 67 (62%) patients underwent surgery during the hospital stay. Prematurity and low birth weight was noted in only 4 (3.7%) the patients. Of the 57 HCWs tested, 19 (33.3%) were harboring Candida species of which 13 had C. tropicalis. Of the 39 environmental sites sampled, 9 sites yielded Candida species. C. tropicalis was isolated from infusion pump, wash basin and medical trolley basket. AFLP analysis was carried out for 21 representative C. tropicalis isolates from various sources along with the blood isolates. AFLP analysis yielded 5 major clades. Colonizing isolates and the blood culture isolates had clonal origin along with the isolates obtained from the hands of health care workers and environmental source. 
Conclusion:
Neonates get colonized with C. tropicalis after admission into ICU from various sources. Surgery is the predominant risk factor for the development of candidemia. And the colonizing strains are responsible for such infection. Also, C. tropicalis hand carriage among health care workers also influence in inflicting candidemia.