Abstract
Candida albicans, a constituent of normal microbial flora of human mucosal surfaces, is a major cause of candidemia in immunocompromised individuals and hospitalized patients with other debilitating diseases. Molecular fingerprinting studies have suggested nosocomial transmission of C. albicans based on the presence of clusters or endemic genotypes in some hospitals. However, intrahospital strain transmission or a common source of infection has not been firmly established. We performed multilocus sequence typing (MLST) on 102 C. albicans bloodstream isolates (representing 92% of all culture-confirmed candidemia patients over a 31-month period at seven major hospitals) to identify patient-to-patient transmission or infection from a common source in Kuwait, a small country in the Middle East where consanguineous marriages are common. Repeat bloodstream isolates from six patients and nine surveillance cultures from other anatomic sites from six patients were also analyzed. Fifty-five isolates belonged to unique genotypes. Forty-seven isolates from 47 patients formed 16 clusters, with each cluster containing 2–9 isolates. Multiple isolates from the same patient from bloodstream or other anatomical sites yielded identical genotypes. We identified four cases of potential patient-to-patient transmission or infection from a common source based on association analysis between patients' clinical/epidemiological data and the corresponding MLST genotypes of eight C. albicans isolates. However, further fingerprinting by whole genome-based amplified fragment length polymorphism (AFLP) analysis yielded 8 different genotypes, ruling out intrahospital transmission of infection. The findings suggest that related strains of C. albicans exist in the community and fingerprinting by MLST alone may complicate hospital infection control measures during outbreak investigations.
Highlights
Candida and other yeast species, like many bacteria, are part of normal microbial flora of skin and mucosal surfaces of the gastrointestinal and genitourinary tracts in humans and give rise to opportunistic infections when host defenses are compromised (Kumamoto, 2011; McManus and Coleman, 2014)
Previous studies based on Multilocus microsatellite typing (MLMT) and multilocus sequence typing (MLST) have reported the presence of endemic genotypes of C. albicans within the same hospital units that were likely involved in intrahospital transmission of infection, patient-to-patient transmission of infection was not conclusively proven (Asmundsdóttir et al, 2008; Maganti et al, 2011; Shin et al, 2011; Escribano et al, 2013; Marcos-Zambrano et al, 2015; Wu et al, 2015)
This study was carried out for two specific objectives: to generate long-term genetic database of C. albicans bloodstream isolates at seven major/tertiary care hospitals and to identify endemic genotypes/cluster isolates that could point toward patient-to-patient or nosocomial transmission of infection among candidemia patients in Kuwait
Summary
Candida and other yeast species, like many bacteria, are part of normal microbial flora of skin and mucosal surfaces of the gastrointestinal and genitourinary tracts in humans and give rise to opportunistic infections when host defenses are compromised (Kumamoto, 2011; McManus and Coleman, 2014). Molecular Fingerprinting of C. albicans in Kuwait broad-spectrum antibiotics or corticosteroid treatment or those with other underlying conditions that compromise host immunity such as diabetes, extremes of age (neonates and elderly), pregnancy and human immunodeficiency virus (HIV) infection (Vincent et al, 2009; Liu et al, 2015; Sun et al, 2016) These conditions predispose the colonized individuals to invasive infections by Candida species (Vincent et al, 2009; Kett et al, 2011). Whole genome sequence-based high-resolution genetic analyses did not support intrahospital transmission of S. aureus between patients with invasive infections These studies showed that highly related pools of bacterial strains exist which could not be differentiated by low-resolution typing methods such as MLST (Nübel et al, 2013; Long et al, 2014; Price et al, 2014). Since whole genome sequencing is not yet routine for fungi, an alternative approach may involve initial fingerprinting by MLST followed by other whole genome-based high-resolution fingerprinting methods on epidemiologically-related isolates for detecting possible patient-to-patient transmission of infection or infection from a common source
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