Objective: Candida parapsilosis is an opportunistic pathogen and is increasingly being associated with invasive candidiasis in critically ill patients. C. parapsilosis is also a commonly isolated species from neonatal intensive care units, causing ~35% of all candidemia cases in neonates. Nosocomial outbreaks are facilitated by spread of C. parapsilosis from health care workers (HCWs) to susceptible patients via hand carriage, its affinity for glucose-containing parenteral nutrition and ability to form biofilms on intravascular devices. This study determined genotypic heterogeneity among C. parapsilosis isolates from candidemia patients in neonatal intensive care units (NICUs) of Maternity Hospital (MH), Kuwait. Isolates from two other hospitals were also included for comparison purposes.
Methods: A total of 70 C. parapsilosis isolates, including 50 bloodstream, two duplicate bloodstream and six surveillance cultures from other body sites of 50 NICU-MH patients, 10 surveillance cultures from nine non-candidemia NICU-MH patients and two surveillance cultures from hands of two HCWs collected in MH during January, 2010 to August, 2014 were used. Additionally, 18 bloodstream isolates from 18 candidemia patients from two other hospitals were used. All isolates were tested by Vitek 2 and a multiplex PCR assay developed recently. Molecular fingerprinting was performed by using six highly discriminatory short tandem repeat microsatellite markers and isolates were assigned a numerical microsatellite genotype (MSG). Phylogenetic relationship among the isolates was determined by constructing a minimum spanning tree (MST) and the dendrogram was generated with bootstrapping by using unweighted pair group method with arithmetic mean (UPGMA) settings.
Results: Sixty-one C. parapsilosis candidemia cases were treated at NICU-MH during the study period. Isolates from 50 patients were available for fingerprinting. All patients were pre-term low birth-weight neonates on total parenteral nutrition. All 88 isolates used in this study were identified as C. parapsilosis sensu stricto by Vitek 2 and multiplex PCR. Fifty bloodstream isolates yielded 37 MSGs; 30 unique MSGs and 7 MSGs from 20 isolates (clusters). Duplicate isolates and five colonizing strains had same MSG as bloodstream isolate; one strain yielded a unique MSG (MSG13). Ten strains from 9 non-candidemia neonates yielded 7 MSGs; two unique MSGs, one (MSG39) for 3 strains from 2 neonates (cluster) and 5 isolates sharing MSG with bloodstream isolates. Two strains from 2 HCWs and all 18 isolates from two hospitals were unique. Thus 88 isolates exhibited 61 MSGs with 29 isolates from 26 patients from MH clustering into 9 MSGs. All cluster isolates in MST were either from NICU-1 patients or mostly included isolates from patients from NICU-1. Four clonal complexes (A to D) (MSGs differing in one marker) were detected in MH.
Conclusions: All C. parapsilosis isolates from two other hospitals belonged to different MSGs showing high discriminatory power of MST. Thirty-three isolates from 29 preterm neonates with/without candidemia at MH belonged to same/closely-related MSGs. The findings suggest persistence of some MSGs in MH, particularly in NICU-1, over several years and these endemic genotypes were likely transmitted to other patients in NICU-1 and other nearby NICUs in MH in Kuwait. Supported by grant YM10/11.

Fingerprinting of bloodstream isolates of Candida parapsilosis suggests horizontal transmission of infections among neonatal intensive care unit patients in Kuwait