Molecular epidemiology and phylogenetic analyses of environmental and clinical isolates of Cryptococcus gattii sensu lato in Taiwan.

BACKGROUND: The rare occurrence of cryptococcosis caused by Cryptococcus gattii sensu lato (C. gattii s.l.) leads to the difficulties in studying the molecular epidemiology of this globally emerging disease. OBJECTIVES: To establish the molecular epidemiological profile of C. gattii s.l. in Taiwan, and understand the genetic relationship between locally endemic and global isolates. METHODS: A nationwide survey on environmental C. gattii s.l. in Taiwan was conducted from 2017 to 2019. The geographic distribution and molecular epidemiology based on multilocus sequence typing (MLST) data of the environmental isolates were compared with 18 previously collected clinical isolates. Phylogenetic analysis was performed to elucidate the genetic relationship between the global isolates and the isolates endemic to Taiwan. RESULTS: From a total of 622 environmental samples, 104 (16.7%) were positive for C. gattii s.l.. Seven sequence types were identified among the environmental isolates. The genetic population structure showed that the environmental and clinical isolates were closely linked by sequence types and geographical locations. Phylogenetic analysis revealed the association between the C. gattii s.l. isolates in Taiwan and those from South America and South Asia. The recombination test suggested that, in Taiwan, the C. gattii sensu stricto (C. gattii s.s). isolates undergo clonal reproduction and sexual recombination, whereas C. deuterogattii isolates were clonal. CONCLUSIONS: The molecular epidemiology of environmental C. gattii s.l. isolates is closely linked to the clinical isolates. Phylogenetic analysis of the environmental isolates provides an insight into the mechanisms underlying reproduction and dispersal of C. gattii s.l. in Taiwan.

Epidemiology of Staphylococcus aureus in neonates on admission to a Chinese neonatal intensive care unit.

PURPOSE: Little is known about the molecular epidemiology of Staphylococcus aureus in Chinese neonatal intensive care units (NICUs). We describe the molecular epidemiology of S. aureus isolated from neonates on admission to Beijing Children's Hospital. METHODS: From May 2015-March 2016, nasal swabs were obtained on admission from 536 neonates. Cultures were also obtained from body sites with suspected infections. S. aureus isolates were characterized by staphylococcal chromosomal cassette (SCCmec) type, staphylococcal protein A (spa) type, multilocus sequence type (MLST), sasX gene, antimicrobial susceptibility and cytotoxicity. Logistic regression assessed risk factors for colonization. RESULTS: Overall, 92 (17%) infants were colonized with S. aureus and 20 (3.7%) were diagnosed with culture-positive S. aureus infection. Of the colonized infants, 70% (64/92) harbored methicillin-susceptible S. aureus (MSSA), 30% (28/92) harbored methicillin-resistant S. aureus (MRSA) while 70% (14/20) of infected infants were culture-positive for MRSA, 30% (6/20) were culture-positive for MSSA. Risk factors for colonization included female sex, age 7-28 days, higher birthweight (3270 IQR [2020-3655] grams) and vaginal delivery (p<0.05). The most common MRSA and MSSA clones were community-associated ST59-SCCmecIVa-t437 (60%) and ST188-t189 (15%), respectively. The sasX gene was not detected. Some MSSA isolates (16%) were penicillin-susceptible and some MRSA isolates (18%) were oxacillin-susceptible. MRSA and MSSA had similar cytotoxicity, but colonizing strains were less cytotoxic than strains associated with infections. CONCLUSIONS: S. aureus colonization was common in infants admitted to our NICU and two community-associated clones predominated. Several non-modifiable risk factors for S. aureus colonization were identified. These results suggest that screening infants for S. aureus upon admission and targeting decolonization of high-risk infants and/or those colonized with high-risk clones could be useful to prevent transmission.