Papers by Mohammad Asadzadeh
Scientific Reports, 2019
Candida parapsilosis causes ~35% of all candidemia cases in neonates. High-resolution fingerprint... more Candida parapsilosis causes ~35% of all candidemia cases in neonates. High-resolution fingerprinting of C. parapsilosis isolates from neonatal intensive care unit (NICU) patients in Maternity Hospital (MH) was performed to identify epidemiologically related strains. Sixty-eight bloodstream/colonizing strains isolated from 59 NICU patients, two isolates from health care workers (HCWs) from MH and 18 bloodstream isolates from two other hospitals were used. Six microsatellite markers were employed, isolates were assigned a numerical microsatellite genotype (MSG), dendrogram was constructed and similarities between genotypes were visualized by minimum spanning tree. Fifty bloodstream isolates from MH yielded 37 MSGs with 20 isolates clustering in 7 MSGs. Duplicate isolates and colonizing strains yielded same/highly similar MSG as bloodstream isolates. Colonizing strains from two non-candidemia patients yielded unique MSGs while others belonged to a cluster. All isolates from HCWs and fr...
PloS one, 2018
Candida auris is an emerging yeast pathogen of global significance. Its multidrug-resistant natur... more Candida auris is an emerging yeast pathogen of global significance. Its multidrug-resistant nature and inadequacies of conventional identification systems pose diagnostic and therapeutic challenges. This study investigated occurrence of C. auris in clinical specimens in Kuwait and its susceptibility to antifungal agents. Clinical yeast strains isolated during 3.5-year period and forming pink-colored colonies on CHROMagar Candida were studied by wet mount examination for microscopic morphology and Vitek 2 yeast identification system. A simple species-specific PCR assay was developed for molecular identification and results were confirmed by PCR-sequencing of rDNA. Antifungal susceptibility testing of one isolate from each patient was determined by Etest. The 280 isolates forming pink-colored colonies on CHROMagar Candida, were identified by Vitek 2 as Candida haemulonii (n = 166), Candida utilis (n = 49), Candida kefyr (n = 45), Candida guilliermondii (n = 9), Candida famata (n = 6) ...
PloS one, 2017
Candida dubliniensis and Candida albicans are two closely related species. Although C. dubliniens... more Candida dubliniensis and Candida albicans are two closely related species. Although C. dubliniensis is less pathogenic, it has a higher propensity to develop resistance to fluconazole and some strains exhibit intrinsic resistance to 5-flucytosine (5-FC). All 5-FC-resistant isolates from Kuwait were previously shown to belong to one of seven internal transcribed spacer (ITS) region of rDNA-based haplotypes. This study performed fingerprinting of C. dubliniensis isolates by multilocus sequence typing (MLST) to determine population structure of 5-FC-resistant and -susceptible strains and compared the results with data from a global collection of isolates. Fifty-two C. dubliniensis isolates previously analyzed and 58 additional isolates mostly collected during 2010-2013 and characterized by phenotypic and molecular methods were used. ITS-based haplotypes were identified by haplotype-specific PCR and/or by PCR-DNA sequencing of rDNA. Population structure was determined by 8-loci-based ML...
Frontiers in Microbiology, 2017
Candida albicans, a constituent of normal microbial flora of human mucosal surfaces, is a major c... more 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.
PloS one, 2015
Candida parapsilosis has now emerged as the second or third most important cause of healthcare-as... more Candida parapsilosis has now emerged as the second or third most important cause of healthcare-associated Candida infections. Molecular studies have shown that phenotypically identified C. parapsilosis isolates represent a complex of three species, namely, C. parapsilosis, C. orthopsilosis and C. metapsilosis. Lodderomyces elongisporus is another species phenotypically closely related to the C. parapsilosis-complex. The aim of this study was to develop a simple, low cost multiplex (m) PCR assay for species-specific identification of C. parapsilosis complex isolates and to study genetic relatedness of C. orthopsilosis isolates in Kuwait. Species-specific amplicons from C. parapsilosis (171 bp), C. orthopsilosis (109 bp), C. metapsilosis (217 bp) and L. elongisporus (258 bp) were obtained in mPCR. Clinical isolates identified as C. parapsilosis (n = 380) by Vitek2 in Kuwait and an international collection of 27 C. parapsilosis complex and L. elongisporus isolates previously characteri...
Mycoses, 2008
This study presents data on antifungal susceptibility of 114 Candida parapsilosis isolates recove... more This study presents data on antifungal susceptibility of 114 Candida parapsilosis isolates recovered from clinical specimens in Kuwait. Candida parapsilosis isolates originating from blood (n = 66) and other clinical specimens (n = 48) were tested by Etest against amphotericin B (AP), caspofungin (CS), 5-flucytosine (FC), fluconazole (FL) and voriconazole (VO). The plates were incubated at 35 degrees C and readings for minimum inhibitory concentrations (MIC) were recorded after 24 and 48 h of incubation. The MIC ranges and MIC(90) read after 48 h were as follows: 0.064-1 and 0.5 microg ml(-1) for AP; 0.125-4 and 1.5 microg ml(-1) for CS; 0.047 to >256 and 1 microg ml(-1) for FL; 0.023 to >32 and 0.125 microg ml(-1) for FC and <0.002-1 and 0.047 microg ml(-1) for VO respectively. According to Clinical Laboratory Standards Institute criteria, all the isolates were susceptible to VO, and resistance against FC and FL was <2%. Eight (7%) isolates exhibited reduced susceptibility (MIC >1 microg ml(-1)) to CS including six isolates with MIC of >or=2 microg ml(-1) at 48 h reading. The antifungal resistance among bloodstream isolates of C. parapsilosis against AP, FL, FC and VO in Kuwait is rare. This is the first report on CS susceptibility of C. parapsilosis isolates from Arabian Gulf region.
BMC Infectious Diseases, 2012
Background: Candida albicans is the most pathogenic Candida species but shares many phenotypic fe... more Background: Candida albicans is the most pathogenic Candida species but shares many phenotypic features with Candida dubliniensis and may, therefore, be misidentified in clinical microbiology laboratories. Candidemia cases due to C. dubliniensis are increasingly being reported in recent years. Accurate identification is warranted since mortality rates are highest for C. albicans infections, however, C. dubliniensis has the propensity to develop resistance against azoles more easily. We developed a duplex PCR assay for rapid detection and differentiation of C. albicans from C. dubliniensis for resource-poor settings equipped with basic PCR technology and compared its performance with three phenotypic methods. Methods: Duplex PCR was performed on 122 germ tube positive and 12 germ tube negative isolates of Candida species previously identified by assimilation profiles on Vitek 2 ID-YST system. Typical morphologic characteristics on simplified sunflower seed agar (SSA), and reaction with a commercial (Bichro-Dubli) latex agglutination test were also performed. The assay was further applied on 239 clinical yeast and yeast-like fungi and results were confirmed by DNA sequencing of internal transcribed spacer (ITS) region of rDNA. Results: The results of duplex PCR assay for 122 germ tube positive and 12 germ tube negative isolates of Candida species were comparable to their identification by Vitek 2 ID-YST system, colony characteristics on SSA and latex agglutination test. Application of duplex PCR also correctly identified all 148 C. albicans and 50 C. dubliniensis strains among 239 yeast-like fungi. Conclusions: The data show that both, duplex PCR and Bichro-Dubli are reliable tests for rapid (within few hours) identification of clinical yeast isolates as C. dubliniensis or C. albicans. However, duplex PCR may be applied directly on clinical yeast isolates for their identification as C. dubliniensis or C. albicans as it does not require prior testing for germ tube formation or latex Candida agglutination.
PLOS ONE, 2019
Occurrence of Candida nivariensis and Candida bracarensis, two species phenotypically similar to ... more Occurrence of Candida nivariensis and Candida bracarensis, two species phenotypically similar to Candida glabrata sensu stricto, in human clinical samples from different geographical settings remains unknown. This study developed a low-cost multiplex PCR (mPCR) and three species-specific singleplex PCR assays. Reference strains of common Candida species were used during development and the performance of mPCR and singleplex PCR assays was evaluated with 440 clinical C. glabrata sensu lato isolates. The internal transcribed spacer (ITS) region of rDNA was also sequenced from 85 selected isolates and rDNA sequence variations were used for determining genetic relatedness among the isolates by using MEGA X software. Species-specific amplicons for C. glabrata (~360 bp), C. nivariensis (~250 bp) and C. bracarensis (~180 bp) were obtained in mPCR while no amplicon was obtained from other Candida species. The three singleplex PCR assays also yielded expected results with reference strains of Candida species. The mPCR amplified 360 bp amplicon from all 440 C. glabrata sensu lato isolates thus identifying all clinical isolates in Kuwait as C. glabrata sensu stricto. The results of mPCR were confirmed for all 440 isolates as they yielded an amplicon only in C. glabrata sensu stricto-specific singleplex PCR assay. The rDNA sequence data identified 28 ITS haplotypes among 85 isolates with 18 isolates belonging to unique haplotypes and 67 isolates belonging to 10 cluster haplotypes. In conclusion, we have developed a simple, low-cost mPCR assay for rapid differentiation of C. glabrata sensu stricto from C. nivariensis and C. bracarensis. Our data obtained from a large collection of clinical C. glabrata sensu lato isolates show that C. nivariensis and C. bracarensis are rare pathogens in Kuwait. Considerable genetic diversity among C. glabrata sensu stricto isolates was also indicated by rDNA sequence analyses.
Journal of Fungi, 2020
The emerging, often multidrug-resistant Candida auris is increasingly being associated with outbr... more The emerging, often multidrug-resistant Candida auris is increasingly being associated with outbreaks in healthcare facilities. Here we describe the molecular epidemiology of a C. auris outbreak during 18 months, which started in 2018 in the high dependency unit (HDU) of a secondary-care hospital in Kuwait. Demographic and clinical data for candidemia and colonized patients were prospectively recorded. Clinical and environmental isolates were subjected to phenotypic and molecular identification; antifungal susceptibility testing by broth microdilution method; PCR-sequencing of ERG11 and FKS1 for resistance mechanisms to triazoles and echinocandins, respectively; and molecular fingerprinting by short tandem repeat (STR) analyses. Seventy-one (17 candidemic and 54 colonized) patients including 26 with candiduria and seven environmental samples yielded C. auris. All isolates were identified as C. auris by Vitek2, MALDI-TOF MS, PCR amplification and/or PCR-sequencing of rDNA. Twelve can...
Medical Principles and Practice, 2020
Objective: C. nivariensis is a rare Candida species which is phenotypically closely related to Ca... more Objective: C. nivariensis is a rare Candida species which is phenotypically closely related to Candida glabrata and Candida bracarensis. The 3 species form the C. glabrata sensu lato complex. Here, we describe the first isolation and characterization of a C. nivariensis isolate cultured from the tracheal aspirate obtained from a young man in Kuwait. Materials and Methods: The yeast isolate was initially tested by VITEK 2 followed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and multiplex PCR. The identification was confirmed by sequencing of internal transcribed spacer (ITS) region of rDNA. Antifungal susceptibility testing was performed by Etest, and phylogenetic comparison with other international strains was carried out by using MEGA version 7 software. Results: The C. nivariensis isolate was misidentified by VITEK 2, but correctly identified by MALDI-TOF MS with updated software and multiplex PCR. The identity was confirmed by se...
Journal of Fungi, 2020
Fungal infections are an increasingly important public health issue, yet accurate statistics on f... more Fungal infections are an increasingly important public health issue, yet accurate statistics on fungal burden worldwide and in Kuwait are scarce. Here we estimate the incidence and prevalence of fungal infections in Kuwait. Population statistics from 2018 collected by the Public Authority for Civil Information were used, as well as data from the Ministry of Health. A literature search for Kuwait data on mycotic diseases and population at risk (chronic obstructive pulmonary disease, HIV infection/AIDS, cancer, and transplant patients) was conducted. The population in 2018 was estimated at 4,226,920 million people: 1,303,246 million Kuwaitis and 2,923,674 million expatriates. We determined the annual burden of serious fungal infections number (per 100,000) from high to low based on earlier reported fungal rates for populations at risk: recurrent Candida vaginitis 54,842 (2595); severe asthma with fungal sensitisation 10,411 (246); allergic bronchopulmonary aspergillosis, 7887 (187); c...
PLOS ONE, 2019
Changing trends in incidence and antifungal susceptibility patterns of six Candida species causin... more Changing trends in incidence and antifungal susceptibility patterns of six Candida species causing candidemia in Kuwait between 2006-2017 are reported. A total of 2075 isolates obtained from 1448 patients were analyzed. Identity of Candida species isolates was determined by phenotypic methods and confirmed by PCR amplification/PCR-sequencing of rDNA and/or MALDI-TOF MS. Antifungal susceptibility was determined by Etest. C. albicans accounted for 539 (37.22%) cases followed by C.
Antimicrobial Agents and Chemotherapy, 2018
Candida glabrata is intrinsically less susceptible to azoles, and resistance to echinocandins and... more Candida glabrata is intrinsically less susceptible to azoles, and resistance to echinocandins and reduced susceptibility (RS) to amphotericin B (AMB) have also been detected. The molecular mechanisms of RS to AMB were investigated in C. glabrata strains in Kuwait by sequence analyses of genes involved in ergosterol biosynthesis.
Medical Mycology, 2012
from oral cavities of human immunodefi ciency virus (HIV)-infected patients with recurrent oral c... more from oral cavities of human immunodefi ciency virus (HIV)-infected patients with recurrent oral candidiasis [5,6], the species has now been shown to have a worldwide distribution [1,2]. It has been recovered from cases of systemic disease in non-HIV-infected subjects, particularly patients receiving cancer chemotherapy or transplantation and patients with liver disease or diabetes [2,7-11]. Despite its occurrence as a minor constituent of microbiota, its role as an emerging yeast pathogen is being increasingly recognized [12-17]. There is paucity of data on population structure of C. dubliniensis isolates. Early studies with a speciesspecifi c Cd25 probe showed that C. dubliniensis isolates comprise two distinct fi ngerprinting groups, Cd25 group I and Cd25 group II [18]. In a later study, Gee et al. [19] sequenced the internal transcribed spacer (ITS) region (including ITS1-5.8S rRNA-ITS2) of rDNA and reported four distinct genotypes. All Cd25 group I isolates belonged to genotype 1 and were recovered mainly from
PLOS ONE, 2020
Objective Candida kefyr causes invasive candidiasis in immunocompromised patients, particularly a... more Objective Candida kefyr causes invasive candidiasis in immunocompromised patients, particularly among those with oncohematological diseases. This study determined the prevalence of C. kefyr among yeast isolates collected during 2011-2018 in Kuwait. Antifungal susceptibility testing (AST) and genotypic heterogeneity among C. kefyr was also studied. Methods Clinical C. kefyr isolates recovered from bloodstream and other specimens during 2011 to 2018 were retrospectively analyzed. All C. kefyr isolates were identified by CHROMagar Candida, Vitek2 and PCR amplification of rDNA. AST was performed by Etest. Molecular basis of resistance to fluconazole and echinocandins was studied by PCR-sequencing of ERG11 and FKS1, respectively. Genotypic heterogeneity was determined with microsatellite-/minisatellite-based primers and for 27 selected isolates by PCR-sequencing of IGS1 region of rDNA. Results Among 8257 yeast strains, 69 C. kefyr (including four bloodstream) isolates were detected by phenotypic and molecular methods. Isolation from urine and respiratory samples from female and male patients was significantly different (P = 0.001). Four isolates showed reduced susceptibility to amphotericin B and one isolate to all (amphotericin B, fluconazole, voriconazole and caspofungin/micafungin) antifungals tested. Fluconazole-resistant isolate contained only synonymous mutations in ERG11. Echinocandin-resistant isolate contained wild-type hotspot-1 and hotspot-2 of FKS1. Fingerprinting with microsatellite-/minisatellitebased primers identified only three types. IGS1 sequencing identified seven haplotypes among 27 selected isolates.
Journal of Medical Microbiology, 2009
Recent molecular studies have led to the recognition of three distinct species within the Candida... more Recent molecular studies have led to the recognition of three distinct species within the Candida parapsilosis complex, namely Candida parapsilosis, Candida orthopsilosis and Candida metapsilosis. As currently available yeast identification systems fail to differentiate these species, there is a paucity of information on their occurrence in different geographical regions. This study describes a simple PCR-based protocol for rapid discrimination among C. parapsilosis, C. orthopsilosis and C. metapsilosis strains by using primers derived from unique sequences within the internally transcribed spacer 1 (ITS1)–5.8 rRNA–ITS2 region. Retrospective analysis of 114 C. parapsilosis-complex isolates recovered from clinical specimens in Kuwait identified 109 as C. parapsilosis, five as C. orthopsilosis and none as C. metapsilosis. The results were further validated by PCR-RFLP patterns of the secondary alcohol dehydrogenase gene fragment. DNA sequencing of the ITS region and the D1/D2 regions ...
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Papers by Mohammad Asadzadeh