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  1. Evaluation of Tween 80 incorporated media to increase pathogen isolation from peritoneal fluid of CAPD patients at Hospital Kuala Lumpur
    Ganapathy Pillay S, Mohd Amin SDW, Masri SN, Joseph NM, Amran F, Van Belkum A, et al.
    Malays J Pathol, 2021 Aug;43(2):261-268.
    PMID: 34448790
    INTRODUCTION: Continuous ambulatory peritoneal dialysis (CAPD)-associated peritonitis remains a major complication in patients on CAPD leading to increased morbidity and mortality. Successful therapy of peritonitis is highly dependent on a positive microbiological culture because narrow spectrum antibiotics are essential to efficiently combat infection. Therefore, this study evaluated the performance of Tween 80 containing media at three different concentrations (0.1%, 1.0% and 2.0%) to increase the pathogen yield from peritoneal fluid in comparison with the standard culture media.

    MATERIALS AND METHODS: Peritoneal fluid samples (n=121) obtained from CAPD patients suspected of peritonitis at Hospital Kuala Lumpur were analysed macroscopically and microscopically prior to culture. All samples were cultured on seven different culture media, including sheep blood agar, MacConkey agar, Sabouraud dextrose agar, brain heart infusion agar and Tween 80 incorporated blood agar. All plates were incubated at an optimum temperature up to 48 hours.

    RESULTS AND CONCLUSION: Among all the culture media investigated, 0.1% to 2.0% Tween 80 incorporated blood agar yielded the highest positive culture (23/121) in comparison with all other standard media, thus lowering the negative culture rate among CAPD patients. Statistical analysis by Chi Square revealed significant differences (p <0.001) between the three concentrations of Tween 80 tested in this study. Among the three different concentrations of Tween 80 optimised in this study, blood agar containing 0.1% Tween 80 generated the best results, achieved by optimum growth of all Gram-positive organisms, Gram-negative organisms and yeast cells simultaneously. Using a small amount of detergent at low cost significantly increased the pathogen yield during CAPD-associated peritonitis.

  2. Fulltext Seroprevalence of Leptospira infection in occupational risk groups in North Khorasan province, Iran
    Hashemi SA, Arzamani K, Abdollahpour G, Beheshti N, Alavinia M, Azimian A, et al.
    Heliyon, 2021 Jan;7(1):e05983.
    PMID: 33506135 DOI: 10.1016/j.heliyon.2021.e05983
    Leptospirosis is an important zoonotic bacterial disease caused by Leptospira spp. Earlier studies from North Khorasan province (Iran) reported the presence of Leptospira in wild canines and rodents. To date, there is no data on the seroprevalence of leptospirosis among humans in this province. This study was performed to determine the prevalence of human leptospiral infection among people with different occupations. The study was conducted in urban and rural areas of the province. Among the serum samples collected from 278 subjects, 3 (1.1%) showed positive reaction with titer of 1:100 by the microscopic agglutination test (MAT). Positive reactions were detected against Leptospira interrogans Canicola and L. interrogans icterohemorrhagic and all these samples were from livestock farmers (n = 3/106, 2.7%). The current study revealed that, though Leptospira infection is low in North Khorasan province, regular monitoring of the livestock and the farmers are important.
  3. Raised levels of Il-6, Il-17a, and Il-22 in fatal leptospirosis
    Wan Yusoff WSY, Abdullah M, Sekawi Z, Amran F, Yuhana MY, Mohd Taib N, et al.
    Eur J Clin Microbiol Infect Dis, 2019 Dec;38(12):2349-2353.
    PMID: 31529307 DOI: 10.1007/s10096-019-03699-5
    Clinical manifestations of leptospirosis range from mild, common cold-like illness, to a life-threatening condition. The host immune response has been hypothesized to play a major role in leptospirosis outcome. Increased levels of inflammatory mediators, such as cytokines, may promote tissue damage that lead to increased disease severity. The question is whether cytokines levels may predict the outcome of leptospirosis and guide patient management. This study aimed to assess the association between Th1-, Th2-, and Th17-related cytokines with the clinical outcome of patients with leptospirosis. Different cytokine levels were measured in fifty-two plasma samples of hospitalized patients diagnosed with leptospirosis in Malaysia (January 2016-December 2017). Patients were divided into two separate categories: survived (n = 40) and fatal outcome (n = 12). Nineteen plasma samples from healthy individuals were obtained as controls. Cytokine quantification was performed using Simple Plex™ assays from ProteinSimple (San Jose, CA, USA). Measurements were done in triplicate and statistical analysis was performed using GraphPad software and SPSS v20. IL-6 (p = 0.033), IL-17A (p = 0.022), and IL-22 (p = 0.046) were significantly elevated in fatal cases. IL-17A concentration (OR 1.115; 95% CI 1.010-1.231) appeared to be an independent predictor of fatality of leptospirosis. Significantly higher levels of TNF-α (p ≤ 0.0001), IL-6 (p ≤ 0.0001), IL-10 (p ≤ 0.0001), IL-12 (p ≤ 0.0001), IL17A (p ≤ 0.0001), and IL-18 (p ≤ 0.0001) were observed among leptospirosis patients in comparison with healthy controls. Our study shows that certain cytokine levels may serve as possible prognostic biomarkers in leptospirosis patients.
  4. Physiological and proteomic analysis of Stenotrophomonas maltophilia grown under the iron-limited condition
    Azman A, Vasodavan K, Joseph N, Kumar S, Hamat RA, Nordin SA, et al.
    Future Microbiol, 2019 Nov;14:1417-1428.
    PMID: 31777284 DOI: 10.2217/fmb-2019-0174
    Aims: To study physiological and proteomic analysis of Stenotrophomonas maltophilia grown under iron-limited condition. Methods: One clinical and environmental S. maltophilia isolates grown under iron-depleted conditions were studied for siderophore production, ability to kill nematodes and alteration in protein expression using isobaric tags for relative and absolute quantification (ITRAQ). Results & conclusions: Siderophore production was observed in both clinical and environmental strains under iron-depleted conditions. Caenorhabditis elegans assay showed higher killing rate under iron-depleted (96%) compared with normal condition (76%). The proteins identified revealed, 96 proteins upregulated and 26 proteins downregulated for the two isolates under iron depletion. The upregulated proteins included several iron acquisition proteins, metabolic proteins and putative virulence proteins.
  5. Fulltext Bioactive 2-(Methyldithio)Pyridine-3-Carbonitrile from Persian Shallot (Allium stipitatum Regel.) Exerts Broad-Spectrum Antimicrobial Activity
    Karunanidhi A, Ghaznavi-Rad E, Jeevajothi Nathan J, Joseph N, Chigurupati S, Mohd Fauzi F, et al.
    Molecules, 2019 Mar 13;24(6).
    PMID: 30871159 DOI: 10.3390/molecules24061003
    Antibiotic resistance is a problem that continues to challenge the healthcare sector, especially in clinically significant pathogens like methicillin-resistant Staphylococcus aureus (MRSA). Herein is described the isolation and structure elucidation of a bioactive compound from Allium stipitatum with antimicrobial activity. Crude Allium stipitatum dichloromethane extract (ASDE) was subjected to systematic purification by chromatographic procedures to afford various bioactive fractions. A fraction that exhibited anti-MRSA activity (4 µg·mL-1) was further characterized to determine the structure. The structure of the compound was elucidated as 2-(methyldithio)pyridine-3-carbonitrile (2-Medpy-3-CN). The 2-Medpy-3-CN compound, which was screened for antimicrobial activity, exhibited minimum inhibitory concentrations (MICs) in the range of 0.5 to >64 µg·mL-1 for tested bacterial species and 0.25 to 2 µg·mL-1 for Candida spp. Further studies are important to confirm the drug target and mechanism of action.
  6. Humoral immune consequences of Staphylococcus aureus ST239-associated bacteremia
    Ghasemzadeh-Moghaddam H, van Wamel W, van Belkum A, Hamat RA, Tavakol M, Neela VK
    Eur J Clin Microbiol Infect Dis, 2018 Feb;37(2):255-263.
    PMID: 29103153 DOI: 10.1007/s10096-017-3124-3
    The humoral immune responses against 46 different staphylococcal antigens in 27 bacteremia patients infected by clonally related methicillin-resistant Staphylococcus aureus (MRSA) strains of a single sequence type (ST) 239 were investigated. A group of non-infected patients (n = 31) hospitalized for different reasons served as controls. All strains were confirmed as ST 239 by S. aureus and mecA-specific PCR, spa, and multi-locus sequence typing (MLST). In each bacteremia patient, a unique pattern of S. aureus antigen-specific immune responses after infection was observed. Antibody levels among bacteremia patients were significantly higher than controls for HlgB (P = 0.001), LukD (P = 0.009), LukF (P = 0.0001), SEA (P = 0.0001), SEB (P = 0.011), SEC (P = 0.010), SEQ (P = 0.049), IsaA (P = 0.043), IsdA (P = 0.038), IsdH (P = 0.01), SdrD (P = 0.001), SdrE (P = 0.046), EsxA (P = 0.0001), and SA0104 (P = 0.0001). On the other hand, the antibody levels were significantly higher among controls for SSL3 (P = 0.009), SSL9 (P = 0.002), and SSL10 (P = 0.007) when the IgG level on the day of infection was compared with that measured on the day of admission. Diversity was observed in the immune response against the antigens. However, a set of antigens (IsaA, IsdA, IsdH, SdrD, and HlgB) triggered a similar type of immune response in different individuals. We suggest that these antigens could be considered when developing a multi-component (passive) vaccine. SEA and/or its specific antibodies seem to play a critical role during ST239 MRSA bacteremia and SEA-targeted therapy may be a strategy to be considered.
  7. Fulltext Antibacterial and Antibiofilm Activities of Nonpolar Extracts of Allium stipitatum Regel. against Multidrug Resistant Bacteria
    Karunanidhi A, Ghaznavi-Rad E, Hamat RA, Pichika MR, Lung LTT, Mohd Fauzi F, et al.
    Biomed Res Int, 2018;2018:9845075.
    PMID: 30105271 DOI: 10.1155/2018/9845075
    The present study assessed the in vitro antibacterial and antibiofilm potential of hexane (ASHE) and dichloromethane (ASDE) extracts of Allium stipitatum (Persian shallot) against planktonic cells and biofilm structures of clinically significant antibiotic resistant pathogens, with a special emphasis on methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and emerging pathogens, Acinetobacter baumannii and Stenotrophomonas maltophilia. Antibacterial activities were determined through disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill kinetics, and electron microscopy. Antibiofilm activity was assessed by XTT [2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide] reduction assay and by confocal laser scanning microscopy (CLSM). The zone of inhibition ranged from 13 to 33 mm, while the MICs and MBCs ranged from 16 to 1024 μg mL-1. Both ASHE and ASDE completely eradicated overnight cultures of the test microorganisms, including antibiotic resistant strains. Time-kill studies showed that the extracts were strongly bactericidal against planktonic cultures of S. aureus, MRSA, Acinetobacter baumannii, and S. maltophilia as early as 4 hours postinoculation (hpi). ASHE and ASDE were shown to inhibit preformed biofilms of the four biofilm phenotypes tested. Our results demonstrate the potential therapeutic application of ASHE and ASDE to inhibit the growth of gram-positive and gram-negative biofilms of clinical significance and warrant further investigation of the potential of A. stipitatum bulbs against biofilm-related drug resistance.
  8. Differences in humoral immune response between patients with or without nasal carriage of Staphylococcus aureus
    Ghasemzadeh-Moghaddam H, van Wamel W, van Belkum A, Hamat RA, Neela VK
    Eur J Clin Microbiol Infect Dis, 2017 Mar;36(3):451-458.
    PMID: 27815779 DOI: 10.1007/s10096-016-2817-3
    The humoral immune response against 43 staphylococcal antigens was compared among hospitalized patients where none of them had any staphylococcal infection on the day of admission with or without nasal Staphylococcus aureus carriage. Fifty-nine carriers and 59 matched non-carriers were studied. The carriers harbored S. aureus of 35 different spa types, including three t037/ST239 methicillin-resistant S. aureus (MRSA) (5.1%). Among the 118 patients, 31 acquired S. aureus during hospitalization. In colonized and non-colonized patients, unique patterns of S. aureus-specific immune responses were observed. The mean fluorescence indices (MFIs) of antibodies against 36/43 (83.7%) antigens were seen to be elevated among carriers. The MFI among carriers with acquisition was significantly higher for staphylococcal superantigen-like protein 5 (SSL5, p = 0.028) when compared to carriers without acquisition. High antibody levels against staphylococcal enterotoxin A (SEA) among carriers illustrate its role as a superantigen in both infection and colonization. We also report a dynamic immune response in S. aureus-carrying patients against the recently reported formyl peptide receptor-like inhibitory (FLIPr)-like protein. In the current study, the dynamics of antibodies against staphylococcal antigens among carrier patients seem quite similar to non-carrier patients. To better understand the dynamic immunogenicity during S. aureus infection and colonization, artificial colonization studies and investigation of the changes in the levels of antibodies against other staphylococcal antigens are recommended.
  9. Fulltext Allium stipitatum Extract Exhibits In Vivo Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus and Accelerates Burn Wound Healing in a Full-Thickness Murine Burn Model
    Karunanidhi A, Ghaznavi-Rad E, Jeevajothi Nathan J, Abba Y, van Belkum A, Neela V
    Evid Based Complement Alternat Med, 2017;2017:1914732.
    PMID: 28321262 DOI: 10.1155/2017/1914732
    The in vivo antibacterial and burn wound healing potency of Persian shallot bulbs (Allium stipitatum) were explored in a mice burn model infected with methicillin-resistant Staphylococcus aureus (MRSA). Hexane (ASHE) and dichloromethane (ASDE) extracts were tested. Female BALB/c mice were inflicted with third-degree thermal injury followed by infection with MRSA. ASHE and ASDE formulated with simple ointment base (SOB) at concentrations of 1%, 2%, and 5% (w/w) were topically applied to burn wounds twice a day for 20 days. Silver sulfadiazine (1%) served as drug positive control. Microbiological analysis was carried out on 1, 2, 3, 4, and 5 days postwounding (dpw) and histopathological analysis at the end of the experiment (20 dpw). Both ointments demonstrated strong antibacterial activity with complete elimination of MRSA at 48-72 h after infection. The rate of wound contraction was higher (95-100%) in mice groups treated with ASHE and ASDE ointments after 15 dpw. Histological analysis revealed significant increase (p < 0.05) in epithelialization and collagenation in treated groups. The ASHE and ASDE were found to be relatively noncytotoxic and safe to Vero cell line (383.4 μg mL(-1); 390.6 μg mL(-1)), suggesting the extracts as safe topical antibacterial as well as promising alternatives in managing thermal injuries.
  10. Nasal carriers are more likely to acquire exogenous Staphylococcus aureus strains than non-carriers
    Ghasemzadeh-Moghaddam H, Neela V, van Wamel W, Hamat RA, Shamsudin MN, Hussin NS, et al.
    Clin Microbiol Infect, 2015 Nov;21(11):998.e1-7.
    PMID: 26183299 DOI: 10.1016/j.cmi.2015.07.006
    We performed a prospective observational study in a clinical setting to test the hypothesis that prior colonization by a Staphylococcus aureus strain would protect, by colonization interference or other processes, against de novo colonization and, hence, possible endo-infections by newly acquired S. aureus strains. Three hundred and six patients hospitalized for >7 days were enrolled. For every patient, four nasal swabs (days 1, 3, 5, and 7) were taken, and patients were identified as carriers when a positive nasal culture for S. aureus was obtained on day 1 of hospitalization. For all patients who acquired methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus via colonization and/or infection during hospitalization, strains were collected. We note that our study may suffer from false-negative cultures, local problems with infection control and hospital hygiene, or staphylococcal carriage at alternative anatomical sites. Among all patients, 22% were prior carriers of S. aureus, including 1.9% whom carried MRSA upon admission. The overall nasal staphylococcal carriage rate among dermatology patients was significantly higher than that among neurosurgery patients (n = 25 (55.5%) vs. n = 42 (16.1%), p 0.005). This conclusion held when the carriage definition included individuals who were nasal culture positive on day 1 and day 3 of hospitalization (p 0.0001). All MRSA carriers were dermatology patients. There was significantly less S. aureus acquisition among non-carriers than among carriers during hospitalization (p 0.005). The mean number of days spent in the hospital before experiencing MRSA acquisition in nasal carriers was 5.1, which was significantly lower than the score among non-carriers (22 days, p 0.012). In conclusion, we found that nasal carriage of S. aureus predisposes to rather than protects against staphylococcal acquisition in the nose, thereby refuting our null hypothesis.
  11. Fulltext Comparative Exoproteomics and Host Inflammatory Response in Staphylococcus aureus Skin and Soft Tissue Infections, Bacteremia, and Subclinical Colonization
    Liew YK, Awang Hamat R, van Belkum A, Chong PP, Neela V
    Clin Vaccine Immunol, 2015 May;22(5):593-603.
    PMID: 25809633 DOI: 10.1128/CVI.00493-14
    The exoproteome of Staphylococcus aureus contains enzymes and virulence factors that are important for host adaptation. We investigated the exoprotein profiles and cytokine/chemokine responses obtained in three different S. aureus-host interaction scenarios by using two-dimensional gel electrophoresis (2-DGE) and two-dimensional immunoblotting (2D-IB) combined with tandem mass spectrometry (MS/MS) and cytometric bead array techniques. The scenarios included S. aureus bacteremia, skin and soft tissue infections (SSTIs), and healthy carriage. By the 2-DGE approach, 12 exoproteins (the chaperone protein DnaK, a phosphoglycerate kinase [Pgk], the chaperone GroEL, a multisensor hybrid histidine kinase, a 3-methyl-2-oxobutanoate hydroxymethyltransferase [PanB], cysteine synthase A, an N-acetyltransferase, four isoforms of elongation factor Tu [EF-Tu], and one signature protein spot that could not be reliably identified by MS/MS) were found to be consistently present in more than 50% of the bacteremia isolates, while none of the SSTI or healthy-carrier isolates showed any of these proteins. By the 2D-IB approach, we also identified five antigens (methionine aminopeptidase [MetAPs], exotoxin 15 [Set15], a peptidoglycan hydrolase [LytM], an alkyl hydroperoxide reductase [AhpC], and a haptoglobin-binding heme uptake protein [HarA]) specific for SSTI cases. Cytokine and chemokine production varied during the course of different infection types and carriage. Monokine induced by gamma interferon (MIG) was more highly stimulated in bacteremia patients than in SSTI patients and healthy carriers, especially during the acute phase of infection. MIG could therefore be further explored as a potential biomarker of bacteremia. In conclusion, 12 exoproteins from bacteremia isolates, MIG production, and five antigenic proteins identified during SSTIs should be further investigated for potential use as diagnostic markers.
  12. Fulltext Antimicrobial susceptibility profiles, serotype distribution and virulence determinants among invasive, non-invasive and colonizing Streptococcus agalactiae (group B streptococcus) from Malaysian patients
    Eskandarian N, Ismail Z, Neela V, van Belkum A, Desa MN, Amin Nordin S
    Eur J Clin Microbiol Infect Dis, 2015 Mar;34(3):579-84.
    PMID: 25359580 DOI: 10.1007/s10096-014-2265-x
    A total of 103 group B streptococci (GBS) including 22 invasive, 21 non-invasive, and 60 colonizing isolates were collected in a Malaysian hospital (June 2010-October 2011). Isolates were characterized by conventional and molecular serotyping and analyzed for scpB, lmb, hylB, cylE, bac, bca and rib gene content. Antimicrobial susceptibility to penicillins, macrolides, lincosamides, quinolones and tetracyclines was determined using disk diffusion and the MICs for penicillin were determined by E-test. Molecular serotyping for all eight serotypes (Ia, Ib, II-VII) was in full accordance with conventional serotyping. Overall, taking CS and MS together, serotype VI was the most common capsular type (22.3 %) followed by VII (21.4 %), III (20.4 %), Ia (17.5 %), V (9.7 %), II (7.7 %) and IV (1 %). Susceptibility to beta-lactam antimicrobials was prevalent (100 %). Resistance rates for erythromycin, clindamycin and tetracycline were 23.3 %, 17.5 % and 71.8 %, respectively. PCR-virulence gene screening showed the presence of cylE, lmb, scpB and hylB in almost all the isolates while rib, bca, and bac genes were found in 29.1 %, 14.6 % and 9.7 % of the isolates. Certain genes were significantly associated with specific serotypes, namely, rib with serotypes Ia, II, III and VI; bca and bac with serotypes II and III. Furthermore, serotype Ia was significantly more common among patients with invasive infections (p 
  13. Methicillin-susceptible and -resistant Staphylococcus aureus with high-level antiseptic and low-level mupirocin resistance in Malaysia
    Ghasemzadeh-Moghaddam H, van Belkum A, Hamat RA, van Wamel W, Neela V
    Microb Drug Resist, 2014 Oct;20(5):472-7.
    PMID: 24841796 DOI: 10.1089/mdr.2013.0222
    The prevalence and spread of mupirocin and antiseptic resistance among colonizing and infectious Staphylococcus aureus were determined. S. aureus isolated from anterior nares and infection sites of patients hospitalized in the largest tertiary care referral hospital in Malaysia was investigated for mupirocin and antiseptic susceptibility testing, and for PCR detection of mupA, qacA/B, and smr genes. Twelve isolates showed resistance to mupirocin by disk diffusion, of which 10 (3.8%) harbored the mupA gene. Minimum inhibitory concentrations (MICs) ranged from 64 to 768 μg/ml for mupA positive and below 46 μg/ml for negative isolates. The mupA was more common among ST239 isolates (70%). The qacA/B was carried in 67 out of 95 methicillin-resistant Staphylococcus aureus (MRSA) (70.5%) and 3 out of 164 methicillin-susceptible Staphylococcus aureus (MSSA) (1.8%), while smr was carried in 6 out of 95 MRSA (6.3%) strains. MICs ranged from 3.9 to 15.6 μg/ml for benzethonium chloride (BTC) and benzalkonium chloride (BKC), and from 10.3 to 20.7 μg/ml for chlorhexidine digluconate (CHG). Isolates with qacA/B and smr or qacA/B alone showed higher MIC (20.7 μg/ml for CHG and 15.6 μg/ml for BTC and BKC) than the isolates that lacked antiseptic resistance genes (10.3 μg/ml for CHG and 3.9 μg/ml for BTC and BKC). In 16 cases, ST239 was isolated from the infection site and the nares simultaneously, and shared identical resistance patterns (qacAB or qacAB+smr), suggesting possible endogenous infection. Spread of low-level mupirocin resistance expressing ST239 MRSA and high-level resistance expressing emerging ST1, co-existing with antiseptic-resistant genes showing elevated MICs, should be monitored for effective infection control.
  14. Quantitative PCR analysis of genes expressed during biofilm development of methicillin resistant Staphylococcus aureus (MRSA)
    Atshan SS, Shamsudin MN, Karunanidhi A, van Belkum A, Lung LT, Sekawi Z, et al.
    Infect Genet Evol, 2013 Aug;18:106-12.
    PMID: 23669446 DOI: 10.1016/j.meegid.2013.05.002
    Staphylococcus aureus biofilm associated infections remains a major clinical concern in patients with indwelling devices. Quantitative real-time PCR (qPCR) can be used to investigate the pathogenic role of such biofilms. We describe qPCRs for 12 adhesion and biofilm-related genes of four S. aureus isolates which were applied during in vitro biofilm development. An endogenous control (16S rRNA) was used for signal normalization. We compared the qPCR results with structural analysis using scanning electron microscopy (SEM). The SEM studies showed different cellular products surrounding the aggregated cells at different times of biofilm formation. Using qPCR, we found that expression levels of the gene encoding fibronectin binding protein A and B and clumping factor B (fnbA/B and clfB), which involves in primary adherence of S. aureus, were significantly increased at 24h and decreased slightly and variably at 48 h when all 4 isolates were considered. The elastin binding protein (ebps) RNA expression level was significantly enhanced more than 6-fold at 24 and 48 h compared to 12h. Similar results were obtained for the intercellular adhesion biofilm required genes type C (icaC). In addition, qPCR revealed a fluctuation in expression levels at different time points of biofilm growth of other genes, indicating that different parameter modes of growth processes are operating at different times.
  15. Fulltext In vitro antibacterial and antibiofilm activities of chlorogenic acid against clinical isolates of Stenotrophomonas maltophilia including the trimethoprim/sulfamethoxazole resistant strain
    Karunanidhi A, Thomas R, van Belkum A, Neela V
    Biomed Res Int, 2013;2013:392058.
    PMID: 23509719 DOI: 10.1155/2013/392058
    The in vitro antibacterial and antibiofilm activity of chlorogenic acid against clinical isolates of Stenotrophomonas maltophilia was investigated through disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill and biofilm assays. A total of 9 clinical S. maltophilia isolates including one isolate resistant to trimethoprim/sulfamethoxazole (TMP/SMX) were tested. The inhibition zone sizes for the isolates ranged from 17 to 29 mm, while the MIC and MBC values ranged from 8 to 16  μg mL(-1) and 16 to 32  μg mL(-1). Chlorogenic acid appeared to be strongly bactericidal at 4x MIC, with a 2-log reduction in viable bacteria at 10 h. In vitro antibiofilm testing showed a 4-fold reduction in biofilm viability at 4x MIC compared to 1x MIC values (0.085 < 0.397 A 490 nm) of chlorogenic acid. The data from this study support the notion that the chlorogenic acid has promising in vitro antibacterial and antibiofilm activities against S. maltophilia.
  16. Diversity in the antimicrobial susceptibility patterns of methicillin-resistant Staphylococcus aureus clones
    Ghaznavi-Rad E, Neela V, Nor Shamsudin M, Ghasemzadeh Moghaddam H, Tavakol M, van Belkum A, et al.
    Eur J Clin Microbiol Infect Dis, 2012 Dec;31(12):3317-21.
    PMID: 23010901 DOI: 10.1007/s10096-012-1698-3
    Methicillin-resistant Staphylococcus aureus (MRSA) is well known for its epidemicity, with the emergence of new clones on a daily basis. Diversity in the clonal types of MRSA challenges the success of treatment, as different clones respond to different sets of antibiotics. However, the antibiotic susceptibility among the isolates within the same clones is largely unexplored. In a previous study on MRSA epidemiology in Malaysia, we identified six major clonal complexes (ST-239-CC8, ST-1-CC1, ST-188-CC1, ST-22-CC22, ST-7-CC7 and ST-1283-CC8). In the present study, we investigated the antibiotic susceptibility patterns of isolates of different clones. Three hundred and eighty-nine MRSA isolates were subjected to the disc diffusion test, oxacillin minimum inhibitory concentration (MIC) determination and assessment of the distribution of macrolide, lincosamide and streptogramin B (MLS(B)) resistance genes. Thirty-six different antibiotic profiles were observed: 30 (83.3 %) among ST-239, 2 (5.6 %) among ST-1283 and 1 (2.8 %) each for ST-1, ST-7, ST-22 and ST-188. All ST-239 (362, 9 %) isolates were multiple drug-resistant (MDR; resistant to more than three classes of antibiotics) and had oxacillin MICs >256 mg/l. Among the 385 clindamycin-resistant isolates, 375 (96.4 %) illustrated inducible resistance (D-zone-positive), while 10 (2.6 %) showed constitutive resistance. The vast majority of the macrolide-resistant isolates carried the ermA gene (95.1 %), followed by ermC (12.9 %). Diversity in the antibiotic susceptibilities of isolates within the clones emphasises the need for continuous surveillance of MDR strains to prescribe the correct antibiotic rather than empirical treatment. This will likely reduce the emergence of new endemic or epidemic resistant MRSA clones.
  17. Modified DNase tube test to detect DNase activity in Stenotrophomonas maltophilia
    Neela V, Thomas R, Rankouhi SZR, Karunanidhi A, Shueh CS, Hamat RA, et al.
    J Med Microbiol, 2012 Dec;61(Pt 12):1792-1794.
    PMID: 22956752 DOI: 10.1099/jmm.0.049403-0
  18. Fulltext Stenotrophomonas maltophilia in Malaysia: molecular epidemiology and trimethoprim-sulfamethoxazole resistance
    Neela V, Rankouhi SZ, van Belkum A, Goering RV, Awang R
    Int J Infect Dis, 2012 Aug;16(8):e603-7.
    PMID: 22698885 DOI: 10.1016/j.ijid.2012.04.004
    Stenotrophomonas maltophilia is a recently identified nosocomial pathogen in Malaysia. Despite limited pathogenicity, its rate of isolation has increased in recent years. The aim of this study was to investigate the antibiotic susceptibility patterns, antibiotic resistance determinants, and the epidemiology of S. maltophilia at the largest tertiary care hospital in Malaysia.
  19. mec-associated dru typing in the epidemiological analysis of ST239 MRSA in Malaysia
    Ghaznavi-Rad E, Goering RV, Nor Shamsudin M, Weng PL, Sekawi Z, Tavakol M, et al.
    Eur J Clin Microbiol Infect Dis, 2011 Nov;30(11):1365-9.
    PMID: 21479532 DOI: 10.1007/s10096-011-1230-1
    The usefulness of mec-associated dru typing in the epidemiological analysis of methicillin-resistant Staphylococcus aureus (MRSA) isolated in Malaysia was investigated and compared with pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and spa and SCCmec typing. The isolates studied included all MRSA types in Malaysia. Multilocus sequence type ST188 and ST1 isolates were highly clonal by all typing methods. However, the dru typing of ST239 isolates produced the clearest discrimination between SCCmec IIIa and III isolates, yielding more subtypes than any other method. Evaluation of the discriminatory power for each method identified dru typing and PFGE as the most discriminatory, with Simpson's index of diversity (SID) values over 89%, including an isolate which was non-typeable by spa, but dru-typed as dt13j. The discriminatory ability of dru typing, especially with closely related MRSA ST239 strains (e.g., Brazilian and Hungarian), underscores its utility as a tool for the epidemiological investigation of MRSA.
  20. Methicillin-susceptible Staphylococcus aureus from clinical and community sources are genetically diverse
    Ghasemzadeh-Moghaddam H, Ghaznavi-Rad E, Sekawi Z, Yun-Khoon L, Aziz MN, Hamat RA, et al.
    Int J Med Microbiol, 2011 Apr;301(4):347-53.
    PMID: 21193348 DOI: 10.1016/j.ijmm.2010.10.004
    Despite the association of methicillin-susceptible S. aureus (MSSA) with several life-threatening diseases, relatively little is known about their clinical epidemiology in Malaysia. We characterized MSSA isolates (n=252) obtained from clinical and community (carriage) sources based on spa sequencing and multilocus sequence typing (MLST). The prevalence of several important virulence genes was determined to further define the molecular characteristics of MSSA clones circulating in Malaysia. Among the 142 clinical and 110 community-acquired MSSA isolates, 98 different spa types were identified, corresponding to 8 different spa clonal clusters (spa-CCs). In addition, MLST analysis revealed 22 sequence types (STs) with 5 singletons corresponding to 12 MLST-CCs. Interestingly, spa-CC084/085 (MLST-CC15) (p=0.038), spa-non-founder 2 (MLST-ST188) (p=0.002), and spa-CC127 (MLST-CC1) (p=0.049) were identified significantly more often among clinical isolates. spa-CC3204 (MLST-CC121) (p=0.02) and spa-CC015 (MLST-CC45) (p=0.0002) were more common among community isolates. Five dominant MLST-CCs (CC8, CC121, CC1, CC45, and CC5) having clear counterparts among the major MRSA clones were also identified in this study. While the MSSA strains are usually genetically heterogeneous, a relatively high frequency (19/7.5%) of ST188 (t189) strains was found, with 57.8% of these strains carrying the Panton-Valentine leukocidin (PVL). Analysis of additional virulence genes showed a frequency of 36.5% and 36.9% for seg and sei and 0.8% and 6.3% for etb and tst genes, respectively. Arginine catabolic mobile element (ACME) was detected in 4 community isolates only. These represent the first isolates harbouring this gene in an Asian region. In conclusion, MSSA from the Malaysian community and their clinical counterparts are genetically diverse, but certain clones occur more often among clinical isolates than among carriage isolates and vice versa.
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