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  1. Ng KP, Kuan CS, Kaur H, Na SL, Atiya N, Velayuthan RD
    Trop Med Int Health, 2015 Nov;20(11):1447-1453.
    PMID: 26216479 DOI: 10.1111/tmi.12577
    To describe a prospective laboratory-based surveillance of Candida species that were collected from different anatomical sites of patients admitted to the University of Malaya Medical Centre, Malaysia, from the year 2000 to 2013.
  2. Lee YQ, Ahmad Kamar A, Velayuthan RD, Chong CW, Teh CSJ
    Pediatr Neonatol, 2021 03;62(2):129-137.
    PMID: 33218933 DOI: 10.1016/j.pedneo.2020.10.002
    BACKGROUND: Gastrointestinal carriage of multidrug resistant (MDR) Gram-negative bacilli, especially Klebsiella pneumoniae and Escherichia coli, was highly associated with severe nosocomial infections. The main objectives of this study were to determine the clonal relatedness of intestinal carriage and transmission risk factors of MDR E. coli and K. pneumoniae amongst preterm infants admitted to the neonatal intensive care unit (NICU).

    METHODS: A prospective cohort study of preterm infants with gestational age 

  3. Jindal HM, Zandi K, Ong KC, Velayuthan RD, Rasid SM, Samudi Raju C, et al.
    PeerJ, 2017;5:e3887.
    PMID: 29018620 DOI: 10.7717/peerj.3887
    BACKGROUND: Antimicrobial peptides (AMPs) are of great potential as novel antibiotics for the treatment of broad spectrum of pathogenic microorganisms including resistant bacteria. In this study, the mechanisms of action and the therapeutic efficacy of the hybrid peptides were examined.

    METHODS: TEM, SEM and ATP efflux assay were used to evaluate the effect of hybrid peptides on the integrity of the pneumococcal cell wall/membrane. DNA retardation assay was assessed to measure the impact of hybrid peptides on the migration of genomic DNA through the agarose gel. In vitro synergistic effect was checked using the chequerboard assay. ICR male mice were used to evaluate the in vivo toxicity and antibacterial activity of the hybrid peptides in a standalone form and in combination with ceftriaxone.

    RESULTS: The results obtained from TEM and SEM indicated that the hybrid peptides caused significant morphological alterations in Streptococcus pneumoniae and disrupting the integrity of the cell wall/membrane. The rapid release of ATP from pneumococcal cells after one hour of incubation proposing that the antibacterial action for the hybrid peptides is based on membrane permeabilization and damage. The DNA retardation assay revealed that at 62.5 µg/ml all the hybrid peptides were capable of binding and preventing the pneumococcal genomic DNA from migrating through the agarose gel. In vitro synergy was observed when pneumococcal cells treated with combinations of hybrid peptides with each other and with conventional drugs erythromycin and ceftriaxone. The in vivo therapeutic efficacy results revealed that the hybrid peptide RN7-IN8 at 20 mg/kg could improve the survival rate of pneumococcal bacteremia infected mice, as 50% of the infected mice survived up to seven days post-infection. In vivo antibacterial efficacy of the hybrid peptide RN7-IN8 was signficantly improved when combined with the standard antibiotic ceftriaxone at (20 mg/kg + 20 mg/kg) as 100% of the infected mice survived up to seven days post-infection.

    DISCUSSION: Our results suggest that attacking and breaching the cell wall/membrane is most probably the principal mechanism for the hybrid peptides. In addition, the hybrid peptides could possess another mechanism of action by inhibiting intracellular functions such as DNA synthesis. AMPs could play a great role in combating antibiotic resistance as they can reduce the therapeutic concentrations of standard drugs.

  4. Lum KY, Tay ST, Le CF, Lee VS, Sabri NH, Velayuthan RD, et al.
    Sci Rep, 2015;5:9657.
    PMID: 25965506 DOI: 10.1038/srep09657
    Candida spp. are the most common causes of fungal infections worldwide. Among the Candida species, Candida albicans remains the predominant species that causes invasive candidiasis in most countries. In this study, we used two peptides, KABT-AMP and uperin 3.6 as templates to develop novel antifungal peptides. Their anticandidal activity was assessed using a combination of MIC, time-killing assay and biofilm reduction assay. Hybrid peptides, KU2 and KU3 containing a mixed backbone of KABT-AMP and Uperin 3.6 demonstrated the most potent anticandidal activity with MIC values ranging from 8-16 mg/L. The number of Trp residues and the amphipathic structure of peptides probably enhanced the anticandidal activity of peptides. Increasing the cationicity of the uperin 3.6 analogues resulted in reduced MIC from the range of 64-128 mg/L to 16-64 mg/L and this was also correlated with the antibiofilm activity and killing kinetics of the peptides. Peptides showed synergistic effects when used in combination with conventional antifungals. Peptides demonstrated low haemolytic activity but significant toxicity on two normal human epithelial cell lines. This study provides us with a better understanding on the structure-activity relationship and the balance between cationicity and hydrophobicity of the peptides although the therapeutic application of the peptides is limited.
  5. Tay ST, Merican AM, Abdul Jabar K, Velayuthan RD, Ayob KA, Lee JL, et al.
    Int J Infect Dis, 2023 Nov;136:77-80.
    PMID: 37660726 DOI: 10.1016/j.ijid.2023.08.025
    We report the isolation of a rare Gram-positive coccobacillary bacterium from synovial fluids of a patient with periprosthetic joint infection on three occasions over an 8-month period. As routine microbiological methods were not able to identify the isolate definitely, sequence analyses of the bacterial 16S ribosomal RNA gene and whole genome were performed. Analysis of the bacterial 16S ribosomal RNA gene showed the highest similarity (98.1%) with that of Falsarthrobacter (previously known as Arthrobacter) nasiphocae, which was first isolated from the nasal cavities of common seals (Phoca vitulina). The genome size of the strain (designated as UM1) is 2.4 Mb. With a high G+C content (70.4 mol%), strain UM1 is phylogenetically most closely related to F. nasiphocae based on whole genome analysis. Strain UM1 was susceptible to vancomycin, linezolid, trimethoprim-sulfamethoxazole, doxycycline, and intermediate to penicillin and ciprofloxacin. Ceftriaxone resistance was noted. The patient who was also on hemodialysis for his end stage kidney disease died approximately 3 weeks following implant removal and fusion with an external fixator. This study describes the first isolation of F. nasiphocae from human clinical samples. The use of emerging technologies has supported more definitive etiological diagnosis associated with rarely encountered organisms in periprosthetic joint infection.
  6. Jindal HM, Le CF, Mohd Yusof MY, Velayuthan RD, Lee VS, Zain SM, et al.
    PLoS One, 2015;10(6):e0128532.
    PMID: 26046345 DOI: 10.1371/journal.pone.0128532
    Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics in order to defeat multidrug-resistant bacteria such as Streptococcus pneumoniae. In this study, thirteen antimicrobial peptides were designed based on two natural peptides indolicidin and ranalexin. Our results revealed that four hybrid peptides RN7-IN10, RN7-IN9, RN7-IN8, and RN7-IN6 possess potent antibacterial activity against 30 pneumococcal clinical isolates (MIC 7.81-15.62µg/ml). These four hybrid peptides also showed broad spectrum antibacterial activity (7.81µg/ml) against S. aureus, methicillin resistant S. aureus (MRSA), and E. coli. Furthermore, the time killing assay results showed that the hybrid peptides were able to eliminate S. pneumoniae within less than one hour which is faster than the standard drugs erythromycin and ceftriaxone. The cytotoxic effects of peptides were tested against human erythrocytes, WRL-68 normal liver cell line, and NL-20 normal lung cell line. The results revealed that none of the thirteen peptides have cytotoxic or hemolytic effects at their MIC values. The in silico molecular docking study was carried out to investigate the binding properties of peptides with three pneumococcal virulent targets by Autodock Vina. RN7IN6 showed a strong affinity to target proteins; autolysin, pneumolysin, and pneumococcal surface protein A (PspA) based on rigid docking studies. Our results suggest that the hybrid peptides could be suitable candidates for antibacterial drug development.
  7. Movahed E, Cheok YY, Tan GMY, Lee CYQ, Cheong HC, Velayuthan RD, et al.
    BMC Immunol, 2018 Nov 08;19(1):32.
    PMID: 30409128 DOI: 10.1186/s12865-018-0269-5
    BACKGROUND: IL-17A has emerged as a key player in the pathologies of inflammation, autoimmune disease, and immunity to microbes since its discovery two decades ago. In this study, we aim to elucidate the activity of IL-17A in the protection against Cryptococcus neoformans, an opportunistic fungus that causes fatal meningoencephalitis among AIDS patients. For this purpose, we examined if C. neoformans infection triggers IL-17A secretion in vivo using wildtype C57BL/6 mice. In addition, an enhanced green fluorescence protein (EGFP) reporter and a knockout (KO) mouse models were used to track the source of IL-17A secretion and explore the protective function of IL-17A, respectively.

    RESULTS: Our findings showed that in vivo model of C. neoformans infection demonstrated induction of abundant IL-17A secretion. By examining the lung bronchoalveolar lavage fluid (BALF), mediastinal lymph node (mLN) and spleen of the IL-17A-EGFP reporter mice, we showed that intranasal inoculation with C. neoformans promoted leukocytes lung infiltration. A large proportion (~ 50%) of the infiltrated CD4+ helper T cell population secreted EGFP, indicating vigorous TH17 activity in the C. neoformans-infected lung. The infection study in IL-17A-KO mice, on the other hand, revealed that absence of IL-17A marginally boosted fungal burden in the lung and accelerated the mouse death.

    CONCLUSION: Therefore, our data suggest that IL-17A is released predominantly from TH17 cells in vivo, which plays a supporting role in the protective immunity against C. neoformans infection.

  8. Ong SY, Tang MM, Dalawi I, Tan WC, Yeoh CA, Kho WM, et al.
    Med J Malaysia, 2020 07;75(4):349-355.
    PMID: 32723993
    OBJECTIVES: High rates of syphilis have been reported worldwide among men who have sex with men (MSM). This study aims to describe the clinical pattern and treatment response of syphilis among human immunodeficiency virus (HIV)-infected MSM in Malaysia.

    METHODS: This is a retrospective study on all HIV-infected MSM with syphilis between 2011 and 2015. Data was collected from case notes in five centres namely Hospital Kuala Lumpur, Hospital Sultanah Bahiyah, Hospital Umum Sarawak, University of Malaya Medical Centre and Hospital Sungai Buloh.

    RESULTS: A total of 294 HIV seropositive MSM with the median age of 29 years (range 16-66) were confirmed to have syphilis. Nearly half (47.6%) were in the age group of 20-29 years. About a quarter (24.1%) was previously infected with syphilis. Eighty-three patients (28.2%) had other concomitant sexually transmitted infection with genital warts being the most frequently reported (17%). The number of patients with early and late syphilis in our cohort were almost equal. The median pre-treatment non-treponemal antibody titre (VDRL or RPR) for early syphilis (1:64) was significantly higher than for late syphilis (1:8) (p<0.0001). The median CD4 count and the number of patients with CD4 <200/μl in early syphilis were comparable to late syphilis. Nearly four-fifth (78.9%) received benzathine-penicillin only, 5.8% doxycycline, 1.4% Cpenicillin, 1% procaine penicillin, and 12.4% a combination of the above medications. About 44% received treatment and were lost to follow-up. Among those who completed 1 -year follow-up after treatment, 72.3% responded to treatment (serological non-reactive - 18.2%, four-fold drop in titre - 10.9%; serofast - 43.6%), 8.5% failed treatment and 17% had re-infection. Excluding those who were re-infected, lost to follow-up and died, the rates of treatment failure were 12.1% and 8.8% for early and late syphilis respectively (p=0.582).

    CONCLUSION: The most common stage of syphilis among MSM with HIV was latent syphilis. Overall, about 8.5% failed treatment at 1-year follow-up.

  9. Lee CJ, Lai LL, See MH, Velayuthan RD, Doon YK, Lim PE, et al.
    World J Surg, 2023 Nov;47(11):2743-2752.
    PMID: 37491402 DOI: 10.1007/s00268-023-07108-z
    BACKGROUND: In recent years, the increase in antibiotics usage locally has led to a worrying emergence of multi-drug resistant organisms (MDRO), with the Malaysian prevalence rate of methicillin-resistant Staphylococcus aureus (MRSA) ranging from 17.2 to 28.1% between 1999 and 2017. A study has shown that 7% of all non-lactational breast abscesses are caused by MRSA. Although aspiration offers less morbidities compared to surgical drainage, about 20% of women infected by MRSA who initially underwent aspiration subsequently require surgical drainage. This study is conducted to determine the link between aetiology, antimicrobial resistance pattern and treatment modalities of breast abscesses.

    METHODS: Retrospective study of reviewing microbiology specimens of breast abscess patients treated at Universiti Malaya Medical Centre from 2015 to 2020. Data collected from microbiology database and electronic medical records were analysed using SPSS V21.

    RESULT: A total of 210 specimens from 153 patients were analysed. One-fifth (19.5%) of the specimens isolated were MDRO. Lactational associated infections had the largest proportion of MDR in comparison to non-lactational and secondary infections (38.5%, 21.7%, 25.7%, respectively; p = 0.23). Staphylococcus epidermidis recorded the highest number of MDR (n = 12) followed by S. aureus (n = 8). Adjusted by aetiological groups, the presence of MDRO is linked to failure of single aspirations (p = 0.554) and significantly doubled the risk of undergoing surgical drainage for resolution (p = 0.041).

    CONCLUSION: MDR in breast abscess should be recognised as an increasing healthcare burden due to a paradigm shift of MDRO and a rise of resistance cases among lactational associated infection that were vulnerable to undergo surgical incision and drainage for resolution.

  10. Chen SL, Ding Y, Apisarnthanarak A, Kalimuddin S, Archuleta S, Omar SFS, et al.
    Sci Rep, 2019 09 13;9(1):13245.
    PMID: 31519972 DOI: 10.1038/s41598-019-49467-5
    The ST131 multilocus sequence type (MLST) of Escherichia coli is a globally successful pathogen whose dissemination is increasing rates of antibiotic resistance. Numerous global surveys have demonstrated the pervasiveness of this clone; in some regions ST131 accounts for up to 30% of all E. coli isolates. However, many regions are underrepresented in these published surveys, including Africa, South America, and Asia. We collected consecutive bloodstream E. coli isolates from three countries in Southeast Asia; ST131 was the most common MLST type. As in other studies, the C2/H30Rx clade accounted for the majority of ST131 strains. Clinical risk factors were similar to other reported studies. However, we found that nearly all of the C2 strains in this study were closely related, forming what we denote the SEA-C2 clone. The SEA-C2 clone is enriched for strains from Asia, particularly Southeast Asia and Singapore. The SEA-C2 clone accounts for all of the excess resistance and virulence of ST131 relative to non-ST131 E. coli. The SEA-C2 strains appear to be locally circulating and dominant in Southeast Asia, despite the intuition that high international connectivity and travel would enable frequent opportunities for other strains to establish themselves.
  11. Kuan CS, Ng KP, Yew SM, Umar Meleh H, Seow HF, How KN, et al.
    Braz J Microbiol, 2023 Sep;54(3):1351-1372.
    PMID: 37351789 DOI: 10.1007/s42770-023-01032-z
    Neoscytalidium dimidiatum and Bipolaris species are fungal plant pathogens that have been reported to cause human diseases. Recently, we have isolated numerous N. dimidiatum and Bipolaris species from the skin scrapings and nails of different patients. In this work, we have sequenced the genome of one strain of N. dimidiatum. The sequenced genome was compared to that of a previously reported Bipolaris papendorfii genome for a better understanding of their complex lifestyle and broad host-range pathogenicity. Both N. dimidiatum UM 880 (~ 43 Mb) and B. papendorfii UM 226 (~ 33 Mb) genomes include 11,015-12,320 putative coding DNA sequences, of which 0.51-2.49% are predicted transposable elements. Analysis of secondary metabolism gene clusters revealed several genes involved in melanin biosynthesis and iron uptake. The arsenal of CAZymes related to plants pathogenicity is comparable between the species, including genes involved in hemicellulose and pectin decomposition. Several important gene encoding keratinolytic peptidases were identified in N. dimidiatum and B. papendorfii, reflecting their potential pathogenic role in causing skin and nail infections. In this study, additional information on the metabolic features of these two species, such as nutritional profiling, pH tolerance, and osmotolerant, are revealed. The genomic characterization of N. dimidiatum and B. papendorfii provides the basis for the future functional studies to gain further insights as to what makes these fungi persist in plants and why they are pathogenic to humans.
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