Clonal distribution and possible micro evolution of methicillin-resistant Staphylococcus aureus strains in a teaching hospital in Malaysia

Objective:To genotypically characterize methicillin-resistant Staphylococcus aureus(MRSA)strains isolated from medical and surgical wards in Universiti Kebangsaan Malaysia Medical Centre(UKMMC)in 2009.Methods:MRSA strains were collected and molecularly typed by pulsed-field gel electrophoresis(PFGE).Results:PFGE typing on 180 MRSA isolated in UKMMC identified 5 pulsotypes(A-E)and 6 singletons,where pulsotypes B and C were suspected to he divergent clones originating from a single ancestor.This study also showed that most MRSA strains were isolated from swab(119 isolates),followed by blood(22 isolates),tracheal aspirate(11isolates)and sputum(10 isolates).On the other hand,urine and bone isolates were less,which were 4 and 1 isolates,respectively.The distribution of different pulsotypes of MRSA among wards suggested that MRSA was communicated in surgical and medical wards in UKMMC,with pulsotype B MRSA as the dominant strain.Besides,it was found that most deceased patients were infected by pulsotype B MRSA,however,no particular pulsotype could be associated with patient age,underlying disease,or ward of admittance.Conclusions:Five pulsotypes of MRSA and 6singletons were identified,with pulsotype B MRSA as the endemic strains circulating in these wards,which is useful in establishment of preventive measures against MRSA transmission.

Morphological and molecular characterization of Acanthamoeba isolatedfrom contact lens paraphernalia in Malaysia: Highlighting the pathogenicpotential of T4 genotype

Objective:To determine the morphological and molecular characterization of Acanthamoeba isolates from contact lens paraphernalia in Malaysia and to investigate their pathogenic potential based on the physiological tolerance.Methods:One hundred and eighty contact lens wearers donated their contact lens,lens storage cases and lens solutions between2018 and 2019.The samples were inoculated onto 1.5%nonnutrient agar plates for 14 d.Polymerase chain reaction(PCR)was performed and the amplified PCR products were sequenced and compared with the published sequences in GenBank.The pathogenic potential of positive isolates was further tested using temperature-tolerance and osmo-tolerance assays.Acanthamoeba species were categorized into three distinct morphological groups established by Pussard and Pons.Results:Acanthamoeba was successfully isolated from 14(7.8%)culture-positive samples in which 11 belong to morphological groupⅡand 3 belong to morphological groupⅢ,respectively.The sequencing of 18 S ribosomal RNA gene led to the identification of the T4 genotype in all the isolated strains.In vitro assays revealed that 9(64.3%)Acanthamoeba isolates were able to grow at 42℃and 1 M mannitol and were thus considered to be highly pathogenic.Conclusions:To the best of our knowledge,this is the first report identifying the Acanthamoeba genotype and their pathogenic potential among contact lens wearers in Malaysia.The potentially pathogenic T4 genotype isolated in this study is the most predominant genotype responsible for human ocular infection worldwide.Hence,increasing attention should be aimed at the prevention of contamination by Acanthamoeba and the disinfection of contact lens paraphernalia.

The role of Dicer1 in the male reproductive tract

Dicer1 is an RNase Ⅲ enzyme necessary for microRNA （miRNA） biogenesis, as it cleaves pre-miRNAs into mature miRNAs, miRNAs are important regulators of gene expression. In recent years, several miRNA-independent roles of Dicer1 have been identified. They include the production of endogenous small interfering RNAs, detoxifying retrotransposon-derived transcripts, and binding to new targets; messenger RNAs and long noncoding RNAs. Further, in this review, the functional significance of Dicer1 in the male reproductive tract is discussed. Conditional Dicer1 knock-out mouse models have demonstrated a requisite role for Dicer in male fertility. Deletion of Dicer1 from somatic or germ cells in the testis cause spermatogenic problems rendering male mice infertile. The lack of Dicer1 in the proximal epididymis causes dedifferentiation of the epithelium, with unbalanced sex steroid receptor expression, defects in epithelial lipid homeostasis, and subsequent male infertility. In addition, Dicer1 ablation from the prostate leads to increased apoptosis of the differentiated luminal cells, followed by epithelial hypotrophy of the ventral prostate. However, further studies are needed to clarify which functions of Dicer1 are responsible for the observed phenotypes in the male reproductive tract.