Displaying publications 21 - 40 of 50 in total

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  1. Ibrahim N, Wajidi MF, Yusof MY, Tay ST
    Trop Biomed, 2011 Dec;28(3):668-71.
    PMID: 22433898 MyJurnal
    The increased frequency of antibiotic resistance is known to be associated with the dissemination of integrons in the Enterobacteriaceae. This study determined the prevalence and type of integrons amongst 160 extended-spectrum beta-lactamase producing enterobacterial isolates kept in our culture collection. Integrons were detected in 98(61.3%) isolates, including 28(62.2%) Escherichia coli, 34(64.2%) Klebsiella spp., 27(61.4%), Enterobacter spp. and 9(50.0%) Citrobacter spp. investigated in this study. Restriction analysis of the integron gene fragments revealed that class I integron was the principal integron detected in 92(57.5%) of our isolates. Class II integron was detected in 6(3.8%) of our isolates, while no class III integron was detected in this study. The high rates of integron prevalence particularly of the class I integron in the E. coli and Klebsiella spp. concur with previous studies in other geographical regions. The higher (≥50%) integron prevalence of Citrobacter and Enterobacter isolates comparing to previous studies suggests the potential of these isolates as sources for dissemination of resistance determinants. The finding in this study serves as a basis for further study on the antibiotic resistance mechanisms of enterobacterial species in this teaching hospital.
  2. Kong BH, Hanifah YA, Yusof MY, Thong KL
    Trop Biomed, 2011 Dec;28(3):563-8.
    PMID: 22433885 MyJurnal
    Acinetobacter baumannii, genomic species 3 and 13TU are being increasingly reported as the most important Acinetobacter species that cause infections in hospitalized patients. These Acinetobacter species are grouped in the Acinetobacter calcoaceticus- Acinetobacter baumannii (Acb) complex. Differentiation of the species in the Acb-complex is limited by phenotypic methods. Therefore, in this study, amplified ribosomal DNA restriction analysis (ARDRA) was applied to confirm the identity A. baumannii strains as well as to differentiate between the subspecies. One hundred and eighty-five strains from Intensive Care Unit, Universiti Malaya Medical Center (UMMC) were successfully identified as A. baumannii by ARDRA. Acinetobacter genomic species 13TU and 15TU were identified in 3 and 1 strains, respectively. ARDRA provides an accurate, rapid and definitive approach towards the identification of the species level in the genus Acinetobacter. This paper reports the first application ARDRA in genospecies identification of Acinetobacter in Malaysia.
  3. Misbah S, Hassan H, Yusof MY, Hanifah YA, AbuBakar S
    Singapore Med J, 2005 Sep;46(9):461-4.
    PMID: 16123830
    This study aims to identify Acinetobacter of clinical isolates from the University of Malaya Medical Centre (UMMC), Kuala Lumpur, to the species level by 16S rDNA sequencing.
  4. Misbah S, AbuBakar S, Hassan H, Hanifah YA, Yusof MY
    J Hosp Infect, 2004 Dec;58(4):254-61.
    PMID: 15564001
    The antibiotic susceptibility profiles and the repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR)-determined genotypes of 109 Acinetobacter strains collected from the University Malaya Medical Center (UMMC), Kuala Lumpur, Malaysia, in 1987 (N=21) and 1996-1998 (N=88) were established. Twelve antibiotic susceptibility profiles of antibiotics used at the UMMC were obtained. In descending order of effectiveness, imipenem, amikacin and ciprofloxacin were the most effective against the Acinetobacter strains. Compared with 1987 isolates, the isolates obtained in 1996-1998 had decreased susceptibility to these antibiotics and were tolerant to the antibiotics up to an MIC90 of > or =256 mg/L. REP-PCR DNA fingerprints of all the isolates revealed the presence of four Acinetobacter spp. lineages; 92% of all the isolates belonged to two dominant lineages (genotypes 1 and 4). Genotype 4 isolates predominant in 1987 showed increased resistance and antibiotic tolerance to imipenem, amikacin and ciprofloxacin compared with the 1996-1998 isolates. In contrast, genotype 1 isolates from 1996-1998 were mainly sensitive to these antibiotics. These findings demonstrate the presence of at least two independent Acinetobacter spp. lineages in the same hospital, and suggest the possibility that genotype 4 Acinetobacter spp. acquired the resistance phenotype in situ, whereas most of the genotype 1 isolates were probably introduced to the hospital in recent years.
  5. Kahar Bador M, Rai V, Yusof MY, Kwong WK, Assadian O
    J Hosp Infect, 2015 Jul;90(3):248-52.
    PMID: 25982193 DOI: 10.1016/j.jhin.2015.03.009
    Inappropriate use of medical gloves may support microbial transmission. New strategies could increase the safety of medical gloves without the risk of patient and surface contamination.
  6. Lim KT, Hanifah YA, Yusof MY, Thong KL
    Indian J Microbiol, 2012 Dec;52(4):593-600.
    PMID: 24293716 DOI: 10.1007/s12088-012-0286-7
    Methicillin sensitive Staphylococcus aureus is an important bacterial pathogen associated with hospital- and community-acquired infections leading to endocarditis, skin tissue infection and pneumonia. The objective of this study was to determine both the genetic characteristics of methicillin-sensitive S. aureus (MSSA) strains, and the occurrence of virulence factors produced by S. aureus strains isolated from UMMC and healthy students in the University from year 2009. Out of 429 nasal swab samples, 67 were MSSA. The prevalence of 21 different virulence genes among 67 Malaysian clinical and community MSSA strains was determined by PCR, and their genetic features were assessed by PCR-RFLP of coa gene, agr types, spa typing and PFGE. The five predominant virulence genes were ica (79 %), efb and fnbA (61 % each), sdrE (57 %) and hlg (45 %). Toxin genes (enterotoxin, etd and pvl) were significantly more common (P 
  7. Alasil SM, Omar R, Ismail S, Yusof MY
    Int J Microbiol, 2014;2014:649420.
    PMID: 24790603 DOI: 10.1155/2014/649420
    The effectiveness of many antimicrobial agents is currently decreasing; therefore, it is important to search for alternative therapeutics. Our study was carried out to assess the in vitro antibiofilm activity using microtiter plate assay, to characterize the bioactive compounds using Ultra Performance Liquid Chromatography-Diode Array Detection and Liquid Chromatography-Mass Spectrometry and to test the oral acute toxicity on Sprague Dawley rats of extract derived from a novel bacterial species of Paenibacillus strain 139SI. Our results indicate that the crude extract and its three identified compounds exhibit strong antibiofilm activity against a broad range of clinically important pathogens. Three potential compounds were identified including an amino acid antibiotic C8H20N3O4P (MW 253.237), phospholipase A2 inhibitor C21H36O5 (MW 368.512), and an antibacterial agent C14H11N3O2 (MW 253.260). The acute toxicity test indicates that the mortality rate among all rats was low and that the biochemical parameters, hematological profile, and histopathology examination of liver and kidneys showed no significant differences between experimental groups (P > 0.05). Overall, our findings suggest that the extract and its purified compounds derived from novel Paenibacillus sp. are nontoxic exhibiting strong antibiofilm activity against Gram-positive and Gram-negative pathogens that can be useful towards new therapeutic management of biofilm-associated infections.
  8. Lim KT, Hanifah YA, Mohd Yusof MY, Ito T, Thong KL
    J Microbiol Immunol Infect, 2013 Jun;46(3):224-33.
    PMID: 23523045 DOI: 10.1016/j.jmii.2013.02.001
    Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) continue to be a problem for clinicians worldwide. The objective of this study was to determine the changes in antibiograms of MRSA and their genotypic characteristics.
  9. Anbazhagan D, Mansor M, Yan GO, Md Yusof MY, Hassan H, Sekaran SD
    PLoS One, 2012;7(7):e36696.
    PMID: 22815678 DOI: 10.1371/journal.pone.0036696
    Quorum sensing is a term that describes an environmental sensing system that allows bacteria to monitor their own population density which contributes significantly to the size and development of the biofilm. Many gram negative bacteria use N-acyl-homoserine lactones as quorum sensing signal molecules. In this study, we sought to find out if the biofilm formation among clinical isolates of Acinetobacter spp. is under the control of autoinducing quorum sensing molecules.
  10. Lim KT, Hanifah YA, Yusof MY, Goering RV, Thong KL
    Diagn Microbiol Infect Dis, 2012 Oct;74(2):106-12.
    PMID: 22770652 DOI: 10.1016/j.diagmicrobio.2012.05.033
    Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main bacterial pathogens responsible for nosocomial infections leading to pneumonia, bloodstream, skin, and soft tissue infections. The objective of this study was to investigate the genomic changes of MRSA in a tertiary hospital between the years 2003, 2004, 2007, and 2008. One hundred fifty-four MRSA strains were characterized by multilocus sequence typing (MLST), spa, and mec-associated dru typing. Among the 154 strains, 29 different dru, 15 spa, and 8 MLST types were identified. Seven sequence types (STs) (ST239, ST22, ST5, ST6, ST80, ST573, and ST241) were identified among 2007-08 strains, although only 2 STs (ST239 and ST20) were observed among 2003 strains. Clones ST239-t037-dt13g, ST22-t032-(dt10a and dt10aw), and 28 other MRSA clones being introduced in 2007-2008 have replaced the ST239-t037 (dt13d, 14h, 13i, 13l, 13m, 15m, 15l, and 11al) clones present in 2003. The predominant MLST clone, ST239 (90.3%), was further distinguished into 7 different spa types and 26 different dru types, including 17 novel dru types. Maximum parsimony tree based on dru repeats revealed that 10 dru types (dt11am, dt13j, dt15n, dt13q, dt13n, dt13p, dt13f, dt13ao, dt12j, dt7v) shared the same MLST-spa types with dt13d, suggesting that these MRSA clones might have evolved from ST239-t037-dt13d. In conclusion, our data showed that the ST239-t037-dt13d clone and other MRSA clones in 2003 were replaced by ST239-t037-dt13g and other new emerging spa and dru types.
  11. Le CF, Jefferies JM, Yusof MY, Sekaran SD, Clarke SC
    Expert Rev Anti Infect Ther, 2012 Jun;10(6):707-19.
    PMID: 22734960 DOI: 10.1586/eri.12.54
    In Malaysia, various aspects of the epidemiology of pneumococcal carriage and disease remain largely unclear due to the lack of supporting data. Although a number of relevant studies have been documented, their individual discrete findings are not sufficient to inform experts on pneumococcal epidemiology at a national level. Therefore, in this review we aim to bring together and systematically evaluate the key information regarding pneumococcal disease epidemiology in Malaysia and provide a comprehensive overview of the data. Major aspects discussed include pneumococcal carriage, disease incidence and prevalence, age factors, invasiveness of pneumococci, serotypes, molecular epidemiology and antibiotic susceptibility. Penicillin resistance is increasingly prevalent and studies suggest that the majority of pneumococcal serotypes causing pneumococcal disease in Malaysia are covered by currently available conjugate vaccines. Continued surveillance is needed to provide a better understanding of pneumococcal epidemiology in Malaysia.
  12. Dhanoa A, Singh VA, Mansor A, Yusof MY, Lim KT, Thong KL
    BMC Infect Dis, 2012;12:270.
    PMID: 23098162 DOI: 10.1186/1471-2334-12-270
    Methicillin-resistant Staphylococcus aureus (MRSA) has of late emerged as a cause of community-acquired infections among immunocompetent adults without risk factors. Skin and soft tissue infections represent the majority of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clinical presentations, whilst invasive and life-threatening illness like necrotizing pneumonia, necrotizing fasciitis, pyomyositis, osteomyelitis and sepsis syndrome are less common. Although more widely described in the pediatric age group, the occurrence of CA-MRSA osteomyelitis in adults is an uncommonly reported entity.
  13. Kassim M, Yusoff KM, Ong G, Sekaran S, Yusof MY, Mansor M
    Fitoterapia, 2012 Sep;83(6):1054-9.
    PMID: 22626749 DOI: 10.1016/j.fitote.2012.05.008
    Malaysian Gelam honey has anti-inflammatory and antibacterial properties, a high antioxidant capacity, and free radical-scavenging activity. Lipopolysaccharide (LPS) stimulates immune cells to sequentially release early pro- and anti-inflammatory cytokines and induces the synthesis of several related enzymes. The aim of this study was to investigate the effect of the intravenous injection of honey in rats with LPS-induced endotoxemia. The results showed that after 4h of treatment, honey reduced cytokine (tumor necrosis factor-α, interleukins 1β, and 10) and NO levels and increased heme oxygenase-1 levels. After 24h, a decrease in cytokines and NO and an increase in HO-1 were seen in all groups, whereas a reduction in HMGB1 occurred only in the honey-treated groups. These results support the further examination of honey as a natural compound for the treatment of a wide range of inflammatory diseases.
  14. Anbazhagan D, Mui WS, Mansor M, Yan GO, Yusof MY, Sekaran SD
    Braz J Microbiol, 2011 Apr;42(2):448-58.
    PMID: 24031653 DOI: 10.1590/S1517-83822011000200006
    Nosocomial infections are major clinical threats to hospitalised patients and represent an important source of morbidity and mortality. It is necessary to develop rapid detection assays of nosocomial pathogens for better prognosis and initiation of antimicrobial therapy in patients. In this study, we present the development of molecular methods for the detection of six common nosocomial pathogens including Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. Conventional multiplex PCR and SYBR Green based real time PCR assays were performed using genus and species specific primers. Blind testing with 300 clinical samples was also carried out. The two assays were found to be sensitive and specific. Eubacterial PCR assay exhibited positive results for 46 clinical isolates from which 43 samples were detected by real time PCR assay. The sensitivity of the assay is about 93.7% in blind test isolates. The PCR results were reconfirmed using the conventional culture method. This assay has the potential to be a rapid, accurate and highly sensitive molecular diagnostic tool for simultaneous detection of Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. This assay has the potential to detect nosocomial pathogens within 5 to 6 hours, helping to initiate infection control measures and appropriate treatment in paediatric and elderly (old aged) patients, pre-and post surgery patients and organ transplant patients and thus reduces their hospitalization duration.
  15. Thong KL, Junnie J, Liew FY, Yusof MY, Hanifah YA
    J Microbiol Biotechnol, 2009 Oct;19(10):1265-70.
    PMID: 19884790
    The objectives of this study were to determine the antibiotypes, SCCmec subtypes, PVL carriage, and genetic diversity of MRSA strains from a tertiary hospital. Sixtysix MRSA strains were selected randomly (2003, 2004, and 2007) and tested for the Panton-Valentine leukocidin gene, mecA gene, and SCCmec type via a PCR. The antibiograms were determined using a standard disc diffusion method, and the genetic diversity of the isolates was determined by PFGE. Thirty-four antibiograms were obtained, with 55% of the 66 strains exhibiting resistance to more than 4 antimicrobials. All the isolates remained susceptible to vancomycin, and low resistance rates were noted for fusidic acid (11%), rifampicin (11%), and clindamycin acid (19%). The MRSA isolates that were multisensitive (n=12) were SCCmec type IV, whereas the rest (multiresistant) were SCCmec type III. Only two isolates (SCCmec type IV) tested positive for PVL, whereas all the isolates were mecA-positive. The PFGE was very discriminative and subtyped the 66 isolates into 55 pulsotypes (F=0.31-1.0). The multisensitive isolates were distinctly different from the multidrug-resistant MRSA. In conclusion, no vancomycin-resistant isolate was observed. The Malaysian MDR MRSA isolates were mostly SCCmec type III and negative for PVL. These strains were genetically distinct from the SCCmec type IV strains, which were sensitive to SXT, tetracycline, and erythromycin. Only two strains were SCCmec IV and PVL-positive. The infections in the hospital concerned were probably caused by multiple subtypes of MRSA.
  16. Sam IC, Tariman H, Chan YF, Bador MK, Yusof MY, Hassan H
    Med J Malaysia, 2008 Dec;63(5):429-30.
    PMID: 19803311 MyJurnal
    Varicella-zoster virus (VZV) infections are a particular problem in healthcare settings. A survey of chickenpox was carried out amongst healthcare workers (HCWs) following potential ward exposures. A prior history of chickenpox was given by 61/98 (62.2%). Of 64 HCWs tested for VZV IgG, 10 (15.6%) were seronegative, indicating susceptibility. The sensitivity, specificity, positive predictive value, and negative predictive value of a history of prior chickenpox were 57.4%, 90%, 96.4%, and 31.0%, respectively. VZV screening of HCWs without a history of chickenpox, and vaccination of susceptible HCWs should be undertaken in this hospital.
  17. Le CF, Yusof MY, Hassan MA, Lee VS, Isa DM, Sekaran SD
    Sci Rep, 2015;5:11886.
    PMID: 26156658 DOI: 10.1038/srep11886
    We have previously designed a series of antimicrobial peptides (AMPs) and in the current study, the in vivo therapeutic efficacy and toxicity were investigated. Among all the peptides, DM3 conferred protection to a substantial proportion of the lethally infected mice caused by a strain of penicillin-resistant Streptococcus pneumoniae. Synergism was reported and therapeutic efficacy was significantly enhanced when DM3 was formulated in combination with penicillin (PEN). No toxicity was observed in mice receiving these treatments. The in silico molecular docking study results showed that, DM3 has a strong affinity towards three protein targets; autolysin and pneumococcal surface protein A (pspA). Thus AMPs could serve as supporting therapeutics in combination with conventional antibiotics to enhance treatment outcome.
  18. Ngeow YF, Weil AF, Khairullah NS, Yusof MY, Luam L, Gaydos C, et al.
    J Paediatr Child Health, 1997 Oct;33(5):422-5.
    PMID: 9401887
    OBJECTIVE: The incidence of Chlamydia pneumoniae and Chlamydia trachomatis infection was studied among infants and young children admitted to hospital for the management of lower respiratory tract infections, over a 12 month period.

    METHODOLOGY: Respiratory secretions were examined for chlamydiae by cell culture, enzyme-linked immunosorbent assay and polymerase chain reaction-enzyme immunoassay. Sera were tested by micro-immunofluorescence for chlamydial IgG, IgM and IgA. Other bacterial and viral pathogens were also looked for by standard cultural and serological methods.

    RESULTS: Of 87 patients aged 2 months-3 years, an aetiologic diagnosis was made in 41 (47.1%). C. pneumoniae and C. trachomatis were each detected in 1 (1.2%) of the patients. Among common bacterial pathogens, Haemophilus influenzae (13.8%) and Streptococcus pneumoniae (8.1%) were the most frequently identified. Respiratory viruses and elevated Mycoplasma pneumoniae antibodies were found in 10.3% and 9.1% of patients, respectively.

    CONCLUSION: Chlamydiae are infrequent causes of community-acquired acute lower respiratory tract infections in infants and very young children in Malaysia.

  19. Tiong V, Thong KL, Yusof MY, Hanifah YA, Sam JI, Hassan H
    Jpn J Infect Dis, 2010 Sep;63(5):317-22.
    PMID: 20858996
    The genetic diversity and antimicrobial resistance rates of clinical Salmonella isolates (2007-2008) at the University of Malaya Medical Centre, Kuala Lumpur, were investigated and the genetic diversity of the isolates was determined by pulsed-field gel electrophoresis (PFGE) and repetitive extragenic palindromic (REP)-PCR. XbaI-PFGE analysis generated 57 profiles (Dice coefficient, F=0.08-1.00), whereas REP-PCR using the REP primer generated only 35 (F=0.34-1.00). PFGE was therefore the more discriminative and reproducible method for assessing the genetic diversity of salmonellae. The antibiograms of 78 Salmonella isolates were assessed against 19 antimicrobials using the disk diffusion method. Twenty serotypes were identified, with the most common being S. Enteritidis (18%) followed by S. Typhimurium (14%), S. Paratyphi B var Java (9%), S. Weltevreden (9%), and S. Corvallis (9%). A total of 38 resistant profiles were defined, with 53.8% of the isolates being resistant to three or more antimicrobials. The highest resistance rates were observed for cephalothin (55.1%), tetracycline (47.4%), and nalidixic acid (35.9%). The presence of multidrug-resistant Salmonella strains is a cause for concern as it may limit the treatment of severe salmonellosis. One multidrug-resistant S. Enteritidis strain was a putative extended-spectrum beta-lactamase producer, based on a double disk diffusion analysis, and was resistant to ceftriaxone (MIC>32 microg/mL). The data generated by this study will contribute towards epidemiological monitoring and investigations of Salmonella infections in Malaysia.
  20. Jamaluddin J, Mohamed Yassin MS, Jamil SN, Mohamed Kamel MA, Yusof MY
    Malays Fam Physician, 2021 Nov 30;16(3):68-76.
    PMID: 34938394 DOI: 10.51866/oa1171
    Introduction: This audit was performed to monitor the diagnosis and management of chronic kidney disease (CKD) according to the clinical practice guidelines (CPGs) of CKD 2018 in a primary care clinic.

    Methods: Patients who attended the clinic from April to June 2019 and fulfilled the diagnosis of CKD were included in this study, except for those diagnosed with a urinary tract infection, pregnant women and those on dialysis. These criteria were set based on the CPGs. The standards were set following discussions with the clinic team members with reference to local guidelines, the 2017 United Kingdom National CKD audit and other relevant studies.

    Results: A total of 384 medical records were included in this audit. Overall, 5 out of 20 criteria for processes and 3 of 8 clinical outcomes for CKD care did not meet the set standards. These included the following: documentation of CKD classification based on albumin category (43.8%); CKD advice (19.0%); dietitian referral (9.1%); nephrologist referral (45.5%); haemoglobin level monitoring (65.7%); overall blood pressure (BP) control (45.3%); BP readings for diabetic kidney disease (DKD) and non-DKD with > 1 g/day of proteinuria (< 130/80 mmHg, 37.0%); eGFR reduction of < 25% over the past year (77.2%). Identified problems included the absence of a CKD registry, eGFR and albuminuria reports, and a dedicated team, among other factors.

    Conclusions: Overall, 8 out of 28 criteria did not meet the standards of CKD care set for this audit. The problems identified in this audit have been addressed. Moreover, strategies have also been formulated to improve the diagnosis and management of CKD in this clinic.

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