Genotyping, antifungal susceptibility testing, and biofilm formation of Trichosporon spp. isolated from urine samples in a University Hospital in Bangkok, Thailand

The basidiomycetes yeast Trichosporon is widespread in the natural environment, but can cause disease, mainly in immunocompromised patients. However, there have been only few studies about this infection in Thailand. In this study, we characterized 53 Trichosporon spp. isolated from urine samples from patients admitted to a single hospital in Bangkok, Thailand over a one-year period from 2019 to 2020. The strains were identified using colony morphology, microscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and nucleotide sequence analysis of intergenic spacer 1 (IGS1). Fifty-one isolates were Trichosporon asahii, and the remaining isolates were Trichosporon inkin and other Trichosporon species. Three genotypes of IGS1-1, 3, and 7 were observed among T. asahii. The sensitivity of the yeasts to the antifungal drugs amphotericin B, fluconazole, and voriconazole ranged from 0.25 to >16 jig ml-1, 0.5-8 jig ml-1, and 0.01-0.25 jig ml-1, respectively. We investigated biofilm formation by the isolates, and no biofilm production was found in one isolate, low biofilm production in forty-four isolates, and medium biofilm production in six isolates. T. inkin produced biofilms at low levels, and Trichosporon spp. produced biofilms at medium levels. This research increases our understanding of the molecular epidemiology of Trichosporon spp. isolated from one university hospital in Bangkok, Thailand, and reveals their genetic diversity, antifungal susceptibility profiles, and capacity for in vitro biofilm production

Accuracy of Loop-Mediated Isothermal Amplification for Diagnosis of Human Leptospirosis in Thailand

There is a lack of diagnostic tests for leptospirosis in technology-restricted settings. We developed loop-mediated isothermal amplification (LAMP) specific for the 16S ribosomal RNA gene (rrs) of pathogenic and intermediate group Leptospira species. The lower limit of detection was 10 genomic equivalents/reaction, and analytical specificity was high; we observed positive reactions for pathogenic/intermediate groups and negative reactions for non-pathogenic Leptospira species and other bacterial species. We evaluated this assay in Thailand by using a case–control study of 133 patients with laboratory-proven leptospirosis and 133 patients with other febrile illnesses. Using admission blood, we found that the rrs LAMP showed positive results in 58 of 133 cases (diagnostic sensitivity = 43.6, 95% confidence interval [CI] = 35.0–52.5) and in 22 of 133 controls (diagnostic specificity = 83.5, 95% CI = 76.0–89.3). Sensitivity was high for 39 patients who were culture positive for Leptospira spp. (84.6, 95% CI = 69.5–94.1). The rrs LAMP can provide an admission diagnosis in approximately half of patients with leptospirosis, but its clinical utility is reduced by a lower specificity

Comparison of Two Multilocus Sequence Based Genotyping Schemes for Leptospira Species

Two independent multilocus sequence based genotyping schemes (denoted here as 7L and 6L for schemes with 7 and 6 loci, respectively) are in use for Leptospira spp., which has led to uncertainty as to which should be adopted by the scientific community. The purpose of this study was to apply the two schemes to a single collection of pathogenic Leptospira, evaluate their performance, and describe the practical advantages and disadvantages of each scheme. We used a variety of phylogenetic approaches to compare the output data and found that the two schemes gave very similar results. 7L has the advantage that it is a conventional multi-locus sequencing typing (MLST) scheme based on housekeeping genes and is supported by a publically accessible database by which genotypes can be readily assigned as known or new sequence types by any investigator, but is currently only applicable to L. interrogans and L. kirschneri. Conversely, 6L can be applied to all pathogenic Leptospira spp., but is not a conventional MLST scheme by design and is not available online. 6L sequences from 271 strains have been released into the public domain, and phylogenetic analysis of new sequences using this scheme requires their download and offline analysis

Molecular characterization and antibiotic resistance of Staphylococcus aureus isolated from clinical specimens in an urban university hospital in Bangkok, Thailand

Little is known about the properties of the current strains of Staphylococcus aureus associated with human infections in Thailand. This study examined the rate of resistance to various antimicrobial agents, prevalence of virulence genes, and biofilm formation ability of 60 clinical S. aureus isolates from a single Thai hospital. Moreover, the Staphylococcus protein A gene (spa) type was determined among methicillin-resistant S. aureus (MRSA) isolates. Most methicillin-susceptible S. aureus isolates were susceptible to antimicrobials, whereas all MRSA isolates were resistant to erythromycin and clindamycin. The major virulence genes among the isolates were hla (100%), sec (26.7%), and hlb (20%). Meanwhile, 46.7% and 1.7% of the strains exhibited low-grade and high-grade biofilm formation, respectively. Our findings revealed the presence of spa types among MRSA isolates were: t032 (37.5%, 6/16), t088 (25%, 4/16), t001 (12.5%, 2/16), t008 (6.25%, 1/16), t034 (6.25%, 1/16), t439 (6.25%, 1/16), and t1928 (6.25%, 1/16). These findings will be useful for future research on anti-virulence therapies and the epidemiology of the strains circulating in our hospital

Differential Interaction between Invasive Thai Group B <i>Streptococcus</i> Sequence Type 283 and Caco-2 Cells

The emergence in Southeast Asia of invasive group B Streptococcus (GBS) infections in adults by sequence type (ST) 283 is suggested to be associated with fish consumption. Genotyping of 55 GBS clinical isolates revealed that 33/44 invasive isolates belonged to ST283/capsular polysaccharide type (CPS) III. This included 15/16 isolates recovered from younger adults aged 16–36 years. Seven ST283/CPSIII isolates from the blood, cerebrospinal fluid, or joint fluid were selected by the patient’s age at random to perform interaction studies with intestinal epithelial Caco-2 monolayers. The invasion efficiency profiles from this study classified these isolates into two groups; a higher invasion efficiency group 1 recovered from patients aged between 23 and 36 years, and a lower invasion efficiency group 2 recovered from the elderly and neonate. Intracellular survival tests revealed that only group 1 members could survive inside Caco-2 cells up to 32 h without replication. Additionally, all isolates tested were able to traverse across polarized Caco-2 monolayers. However, the timing of translocation varied among the isolates. These results indicated the potential of GBS invasion via the gastrointestinal tract and showed phenotypic variations in invasiveness, intracellular survival, and translocation efficiency between genetically closely related ST283 isolates infecting young adults and those infecting the elderly

Sensitivity and specificity of Hcp1-ELISA, OPS-ELISA and Hcp1/OPS-ELISA.

<p>The assay values were calculated from Thai patients who had melioidosis, tuberculosis, scrub typhus, leptospirosis and Thai healthy donors. The cut-off values with Thai healthy donors as controls were used at specificity of 95% for each assay.</p

Scatterplots of individual antibody titers to Hcp1 and OPS in serum samples of 103 melioidosis patients who were survived within one year.

<p>(A) Sera from all time points, (B) sera of week 0, (C) sera of week 12 and (D) sera of week 52. For each plot, the relationship between variables as determined by linear regression (dotted line), Spearman correlation (correlation coefficient, rho) and P-value are shown.</p

Antibody titers to Hcp1 antigen (A) and OPS antigen (B) in melioidosis patients with bacteremia and non-bacteremia patients.

<p>ELISAs were performed on the plates coated with antigens using undiluted sera and two-fold serially diluted sera from patients. Box plots represent 25^th and 75^th percentile boundaries in the box with the median line within the box; the whiskers indicate the 10^th and 90^th percentiles. The plots show antibody titers for each group of patients. The antibody titer was determined by ELISA using cut-off titers at specificity of 95%.</p