Displaying publications 1 - 20 of 139 in total

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  1. Earnshaw VA, Cox J, Wong PL, Saifi R, Walters S, Azwa I, et al.
    AIDS Behav, 2023 Jul;27(7):2103-2112.
    PMID: 36472685 DOI: 10.1007/s10461-022-03942-9
    Stigma in healthcare settings is a pernicious barrier to HIV prevention and treatment in contexts with strong HIV-related structural stigma. Previous work has documented substantial stigma towards key populations and people living with HIV (PLWH) among Malaysian doctors. The perspectives of Malaysian key populations and PLWH, however, remain understudied. In 2021, 34 Malaysian participants representing key populations and PLWH engaged in a photovoice study designed to qualitatively explore their experiences with and hopes for doctor interactions. Many participants reported stigma from their doctors, perceiving that doctors view them as not normal, sinful, misguided, and incapable. Several emphasized that they wear figurative masks to conceal aspects of themselves from doctors. Yet, many also remain hopeful for constructive relationships with doctors. They want their doctors to know that they are bright, capable, kind, and valuable. Interventions are needed to address stigma among doctors working in contexts with strong structural stigma.
  2. Lim SH, Brown SE, Shaw SA, Kamarulzaman A, Altice FL, Beyrer C
    J Homosex, 2020;67(1):104-126.
    PMID: 30307803 DOI: 10.1080/00918369.2018.1525946
    Malay-Muslim men who have sex with men (MSM) are marginalized and hidden in Malaysia, a predominantly Muslim country in southeast Asia. We explored the policy, network, community, and individual factors related to HIV infection among Malay-Muslim MSM through 26 in-depth interviews and one focus group discussion (n = 5) conducted in Kuala Lumpur and Kota Bharu between October 2013 and January 2014. As religion plays an important role in their lives, participants viewed homosexuality as a sin. Low risk perception and misconceptions about HIV/AIDS were common, and most participants expressed reluctance to consult a doctor unless they had symptoms. Additionally, buying condoms was embarrassing and anxiety-producing. Fear of discrimination by health care providers and community hindered participants from disclosing sexual behaviors and accessing health services. Homophobic comments and policies by the government and religious leaders were concerns of participants. A safe and enabling environment is needed to reduce HIV risks among Malay-Muslim MSM.
  3. Tang RY, Lim SH, Lam JE, Nurasykin S, Eileen T, Chan YW
    Med J Malaysia, 2019 12;74(6):472-476.
    PMID: 31929471
    INTRODUCTION: Melioidosis is caused by Burkholderia pseudomallei, a gram-negative aerobic bacillus, found in the soil and surface water. Treating melioidosis has been a challenge in district hospitals due to high usage of broad spectrum antibiotics and prolonged hospitalisation. This study is to review the patients' demography, clinical presentations and microbiological data.

    METHODS: A 5-year retrospective study was carried out on patients admitted with culture positive for melioidosis from year 2013 to 2017 in Hospital Teluk Intan, Perak.

    RESULTS: There were a total of 46 confirmed cases of melioidosis. Majority of the patients were working in the agricultural and farming (28.6%), and factories (25.7%). Thirty-one patients had diabetes mellitus (71.1%). Presentations of patients with melioidosis included pneumonia (54.3%), skin and soft tissue infection (19.6%), deep abscesses (15.2%) and bone and joint infections (13%). An average of 5.8 days was needed to confirm the diagnosis of melioidosis via positive culture. However, only 39.4% of these patients were started on ceftazidime or carbapenem as the empirical therapy. The intensive care unit (ICU) admission rate for melioidosis was 46% and the mortality rate was 52%. Our microbial cultures showed good sensitivity towards cotrimoxazole (97.1%), ceftazidime (100%) and carbapenem (100%).

    CONCLUSION: Melioidosis carries high mortality rate, especially with lung involvement and bacteremia. Physicians should have high clinical suspicion for melioidosis cases to give appropriate antimelioidosis therapy early.

  4. Wong SK, Wong SP, Sim KS, Lim SH, Low YY, Kam TS
    J Nat Prod, 2019 07 26;82(7):1902-1907.
    PMID: 31241923 DOI: 10.1021/acs.jnatprod.9b00255
    Three new alkaloids were isolated from the bark extract of the Malayan Kopsia arborea, viz., arbophyllidine (1), an unusual pentacyclic, monoterpenoid indole characterized by an absence of oxygen atoms and incorporating a new carbon-nitrogen skeleton, and arbophyllinines A (2) and B (3), two pentacyclic corynanthean alkaloids incorporating a hydroxyethyl-substituted tetrahydrofuranone ring. The structures of the alkaloids were deduced based on analysis of the MS and NMR data and confirmed by X-ray diffraction analyses. The absolute configuration of arbophyllidine (1) was established based on experimental and calculated ECD data, while that of arbophyllinine A was based on X-ray diffraction analysis (Cu Kα). A reasonable biosynthetic route to arbophyllidine (1) from a pericine precursor is presented. Arbophyllidine (1) showed pronounced in vitro growth inhibitory activity against the HT-29 human cancer cell line with IC50 6.2 μM.
  5. Nge CE, Sim KS, Lim SH, Thomas NF, Low YY, Kam TS
    J Nat Prod, 2016 10 28;79(10):2709-2717.
    PMID: 27759387
    Examination of the EtOH extract of the Malayan Tabernaemontana corymbosa resulted in the isolation of three new alkaloids, viz., cononuridine (1), an unusual hexacyclic, iboga-derived, monoterpenoid indole characterized by contraction of the tetrahydroazepine C-ring and incorporation of an additional isoxazolidine ring, taberisidine (2), a seco-corynanthean alkaloid, and conofolidine (3), an Aspidosperma-Aspidosperma bisindole that showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, and HCT 116 cells. The structures and absolute configurations of 1 and 3 and the absolute configuration of the novel pyridopyrimidine indole alkaloid vernavosine (4) were confirmed by X-ray diffraction analysis. A reasonable biosynthesis route to cononuridine starting from an iboga precursor is presented.
  6. Lim SH, Alias H, Kien JKW, Akbar M, Kamarulzaman A, Wong LP
    AIDS Educ Prev, 2019 06;31(3):193-205.
    PMID: 31145000 DOI: 10.1521/aeap.2019.31.3.193
    This study aimed to examine the barriers and facilitators to HIV testing and treatment among Malaysian MSM. Between June 2014 and December 2015, in-depth interviews were conducted in 20 HIV-positive MSM recruited from a teaching hospital and NGO in Kuala Lumpur. Thematic analysis was used to identify, analyze, and report themes. Most participants investigated their HIV status after long period of sickness. Others sought testing upon partner's diagnosis and some were diagnosed via blood donation. Barriers to testing include personal (perceived good health, fear of positive result, denial); social and structural factors (stigmatization by health providers and family, lack of information about free HIV testing and long wait time). Barriers to treatment comprise personal factors (perceived HIV as incurable and treatment as complicated), social factors (HIV and homosexual stigma), and cost. Promoting benefits of regular testing and early treatment is needed to improve HIV care continuum among MSM in Malaysia.
  7. Burch WJ, Hart GJ, Lim SH
    AIDS Educ Prev, 2018 04;30(2):85-95.
    PMID: 29688771 DOI: 10.1521/aeap.2018.30.2.85
    Young men who have sex with men (YMSM) are a group at high risk for HIV infection, yet no research has been conducted to understand this population in Malaysia. Semistructured interviews from a combination of YMSM aged 18-25 (n = 20) and local service providers of sexual health services (n = 4) were conducted from May to June 2015. Thematic analysis was used to identify common themes in participant responses from transcripts. Participants reported societal and internalized homophobia, an absence of sex education and difficulty accessing confidential HIV testing. This study provides insights into how homophobia in Malaysian society influences individual risk behavior for HIV in Malaysian YMSM, and makes practical suggestions for more effective HIV prevention in this population.
  8. Lim SH, Mahmood K, Komiyama K, Kam TS
    J Nat Prod, 2008 Jun;71(6):1104-6.
    PMID: 18462006 DOI: 10.1021/np800123g
    A new cycloartane, monocarpinine (1), incorporating a fused tetrahydrofuranyl ring, and a cytotoxic tetracyclic lactam, monomarginine (2), were isolated from a stem bark extract of the Malayan species Monocarpia marginalis. The structures of these compounds were determined using NMR and MS analysis. Monomarginine (2) showed appreciable cytotoxicity toward human KB (both drug-sensitive and drug-resistant) and Jurkat cells.
  9. Lim SH, Lee HB, Ho AS
    Photochem Photobiol, 2011 Sep-Oct;87(5):1152-8.
    PMID: 21534974 DOI: 10.1111/j.1751-1097.2011.00939.x
    In our screening for photosensitizers from natural resources, 15(1)-hydroxypurpurin-7-lactone ethyl methyl diester (compound 1) was isolated for the first time from an Araceae plant. To evaluate the efficacy of compound 1 as a photosensitizer for head and neck cancers, compound 1 was studied in reference to a known photosensitizer pheophorbide-a (Pha), in terms of photophysical properties, singlet oxygen generation and in in vitro experiments (intracellular uptake and phototoxicity assays) in two oral (HSC2 and HSC3) and two nasopharyngeal (HK1 and C666-1) cancer cell lines. In this study, compound 1 exhibited higher intracellular uptake over 24 h compared with Pha in both HSC3 and HK1 cells. When activated by ≥4.8 J cm(-2) of light, compound 1 was slightly more potent as a photosensitizer than Pha by consistently having marginally lower IC(50) values across different cell lines. In flow cytometry experiments to study the mechanism of photoactivated cell death in HSC3, compound 1 was observed to induce more pronounced apoptosis compared with Pha, which may have been driven by the transient G(2)/M cell cycle block which was also observed. These promising results on compound 1 warrant its further investigation as a clinically useful photodynamic therapy agent for head and neck cancer.
  10. Kuan JW, Su AT, Wong SP, Sim XY, Toh SG, Ong TC, et al.
    Transfus Apher Sci, 2015 Oct;53(2):196-204.
    PMID: 25910537 DOI: 10.1016/j.transci.2015.03.017
    There are few randomized trials comparing filgrastim and pegfilgrastim in peripheral blood stem cell mobilization (PBSCM). None of the trials studied the effects of the timing of pegfilgrastim administration on the outcomes of mobilization. We conducted a randomized triple blind control trial comparing the outcomes of filgrastim 5 µg/kg daily from day 3 onwards, 'early' pegfilgrastim 6 mg on day 3 and 'delayed' pegfilgrastim 6 mg on day 7 in cyclophosphamide PBSCM in patients with no previous history of mobilization. Peripheral blood (PB) CD34+ cell count was checked on day 8 and day 11 onward. Apheresis was started when PB CD34+ ≥ 10/µl from day 11 onward. The primary outcome was the successful mobilization rate, defined as cumulative collection of ≥2 × 10(6)/kg CD34+ cells in three or less apheresis. The secondary outcomes were the day of neutrophil and platelet engraftment post transplantation. There were 156 patients randomized and 134 patients' data analyzed. Pegfilgrastim 6 mg day 7 produced highest percentage of successful mobilization, 34 out of 48 (70.8%) analyzed patients, followed by daily filgrastim, 28 out of 44 (63.6%) and day 3 pegfilgrastim, 20 out of 42 (47.6%) (p = 0.075). Pegfilgrastim day 7 and daily filgrastim reported 1.48 (p = 0.014) and 1.49 (p = 0.013) times higher successful mobilization rate respectively as compared to pegfilgrastim day 3 after adjusting for disease, gender and exposure to myelotoxic agent. Multiple myeloma patients were three times more likely to achieve successful mobilization as compared to acute leukemia or lymphoma patients. Pegfilgrastim avoided the overshoot of white cells compared to filgrastim. There was no difference in the duration of both white cells and platelet recovery post transplantation between the three interventional arms.
  11. Chong SCS, Hollingshead BM, Lim SH, Bourne A
    Glob Public Health, 2021 07;16(7):1014-1027.
    PMID: 32985388 DOI: 10.1080/17441692.2020.1822901
    The Malaysian government has committed to 'Fast Tracking the HIV Response' to achieve UNAIDS 2030 targets to end AIDS. The epidemic is concentrated among key populations and has shifted from people who inject drugs to HIV infection through sexual transmission among men who have sex with men, sex workers and transgender people. The aim of this scoping review was to examine social and behavioural research published since 2005 that can inform understanding of each stage of the 90:90:90 treatment cascade (as proposed by UNAIDS), including HIV risk behaviours and testing practices that precede entry. We found a concentration of studies related to predictors or correlates of HIV infections (mostly among men who have sex with men) and a shortfall in literature pertaining to sex workers or transgender people. While several studies examined factors associated with HIV testing, only one examined uptake of antiretroviral therapy and two explored issues of treatment adherence. No study examined broader care and support of people living with HIV. To scale-up effective programmes and apprise investment to achieve the ambitious targets set-out in the Malaysian National HIV/AIDS Strategic Plan, a combination of comprehensive strategic information and evidence generated through primary research is critical.
  12. Ong LY, Pang T, Lim SH, Tan EL, Puthucheary SD
    J Med Microbiol, 1989 Jul;29(3):195-8.
    PMID: 2473209
    A simple adherence test to detect IgM antibodies in patients with typhoid is described. The test utilises the IgM-"capture" approach, in which the test serum is applied to microtitration plate wells previously coated with anti-human IgM, followed by application of a stained Salmonella typhi antigen suspension which shows adherence in positive cases. By this test, 58 (95%) of 61 sera from confirmed cases of typhoid possessed IgM antibodies to the H or O or both antigens of S. typhi. In patients for whom a diagnosis of typhoid was based only on a significant Widal-test titre, 31 (41%) of 76 sera had IgM antibodies to the H or O or both antigens of S. typhi. Some cross-reactivity of the IgM antibodies was detected, especially with the O antigens of S. paratyphi A and B. A total of 82 sera from non-typhoidal fevers (leptospirosis, typhus, dengue fever) showed no reactivity in this test. In normal sera there was no detectable IgM to the O antigen of S. typhi and only a small number (3.9%) had low levels of IgM to the H antigen. The significance and potential importance of this simple, sensitive, specific and economical test is discussed.
  13. Earnshaw VA, Cox J, Wong PL, Saifi R, Walters S, Azwa I, et al.
    AIDS Behav, 2023 Jul;27(7):2055-2069.
    PMID: 36463390 DOI: 10.1007/s10461-022-03938-5
    Photovoice is an action-oriented qualitative method involving photography and story-telling. Although photovoice yields a powerful form of data that can be leveraged for research, intervention, and advocacy, it has arguably been underutilized within HIV research. Online, asynchronous photovoice methods represent a promising alternative to traditional in-person methods, yet their acceptability and feasibility with key populations and people living with HIV (PLWH) have yet to be explored. The current study describes the methods and evaluation of an online, asynchronous photovoice project conducted with 34 members of key populations and PLWH in Malaysia in 2021. A HIPAA-compliant website incorporating a series of instructional videos was created to facilitate participant engagement and data collection. Quantitative and qualitative indicators suggest that participants found the project to be highly acceptable and feasible. Online, asynchronous photovoice methods hold potential for increasing the scale of this powerful and versatile qualitative research method with key populations and PLWH.
  14. Yap IK, Kho MT, Lim SH, Ismail NH, Yam WK, Chong CW
    Mol Biosyst, 2015 Jan;11(1):297-306.
    PMID: 25382376 DOI: 10.1039/c4mb00463a
    Understanding the basal gut bacterial community structure and the host metabolic composition is pivotal for the interpretation of laboratory treatments designed to answer questions pertinent to host-microbe interactions. In this study, we report for the first time the underlying gut microbiota and systemic metabolic composition in BALB/c mice during the acclimatisation period. Our results showed that stress levels were reduced in the first three days of the study when the animals were subjected to repetitive handling daily but the stress levels were increased when handling was carried out at lower frequencies (weekly). We also observed a strong influence of stress on the host metabolism and commensal compositional variability. In addition, temporal biological compartmental variations in the responses were observed. Based on these results, we suggest that consistency in the frequency and duration of laboratory handling is crucial in murine models to minimise the impact of stress levels on the commensal and host metabolism dynamics. Furthermore, caution is advised in consideration of the temporal delay effect when integrating metagenomics and metabonomics data across different biological matrices (i.e. faeces and urine).
  15. Krishnan P, Lee FK, Chong KW, Mai CW, Muhamad A, Lim SH, et al.
    Org. Lett., 2018 12 21;20(24):8014-8018.
    PMID: 30543301 DOI: 10.1021/acs.orglett.8b03592
    Two new monoterpenoid indole alkaloids, alstoscholactine (1) and alstolaxepine (2), were isolated from Alstonia scholaris. Compound 1 represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, whereas compound 2 represents a 6,7- seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. Their structures and absolute configurations were determined by spectroscopic analyses. Compound 1 was successfully semisynthesized from 19 E-vallesamine. Compound 2 induced marked vasorelaxation in rat isolated aortic rings precontracted with phenylephrine.
  16. Ghani MA, Brown SE, Khan F, Wickersham JA, Lim SH, Dhaliwal SK, et al.
    Int J Drug Policy, 2015 Feb;26(2):175-82.
    PMID: 25577322 DOI: 10.1016/j.drugpo.2014.10.002
    BACKGROUND: In Malaysia, compulsory drug detention centres (CDDCs) hold suspected drug users for two years without adjudication. Acute detoxification without healthcare access has been documented. CDDCs are criticized globally due to ineffectiveness in treating addiction and human rights violations. In response, the Malaysian government began transitioning these facilities into voluntary drug treatment centres known as "Cure and Care" (C&C) centres that embrace a holistic treatment-based approach to drug addiction rehabilitation.

    METHODS: An explorative qualitative study was undertaken to explore patient perspectives and satisfaction regarding treatment and services at the new Cure and Care centre in Kota Bharu, Malaysia. A convenience sample of 20 patients was recruited to participate in semi-structured in-depth interviews. Content analysis was used to identify the salient themes.

    RESULTS: Patients identified methadone treatment, psychosocial programs, religious instruction, and recreational activities as important factors contributing to treatment success for addressing both health and addiction needs. Though many had previously been in a CDDC, adherence to treatment in the C&C centre was perceived to be facilitated by the degree of social support, the voluntary nature and the array of new programs available for selection.

    CONCLUSION: C&Cs represents a dramatic shift in the Malaysian government's approach to drug addiction. Our findings demonstrate positive patient experiences associated with the holistic treatment-based approach of these centres. This exploratory study provides additional evidence to document this ongoing policy transition and may guide continued expansion of new holistic drug treatment programs across the country.

  17. Gautam K, Paudel K, Jacobs J, Wickersham JA, Ikhtiaruddin WM, Azwa I, et al.
    JMIR Form Res, 2023 Aug 24;7:e48113.
    PMID: 37616034 DOI: 10.2196/48113
    BACKGROUND: Chemsex-the use of psychoactive drugs to enhance the sexual experience-is an increasing phenomenon globally. Despite the increasing burden and associated harms of chemsex, evidence-based interventions (ie, behavioral and pharmacological) for chemsex users are nonexistent.

    OBJECTIVE: In this study, we assessed the usability and acceptability of a mobile health (mHealth)-delivered safer chemsex package ("PartyPack") as a sexual harm reduction strategy among men who have sex with men in Malaysia-a setting where chemsex is becoming increasingly prevalent.

    METHODS: This study is part of a larger smartphone app-based intervention (ie, JomPrEP; University of Connecticut) designed to improve access to HIV prevention services among Malaysian men who have sex with men. A total of 50 participants were recruited from the Greater Kuala Lumpur region of Malaysia to use the JomPrEP app, which included a feature allowing participants to order PartyPack, for 30 days (March-April 2022). The usability and acceptability of the PartyPack were assessed using self-report, app analytics, and exit interviews (n=20).

    RESULTS: Overall, 8% (4/50) of participants reported having engaged in chemsex in the past 6 months; however, engagement in condomless sex (34/50, 68%) and group sex (9/50, 18%) was much higher. A total of 43 (86%) participants ordered PartyPack, of which 27 (63%) made multiple orders during the 30 days. Most participants (41/43, 95%) reported being satisfied with the PartyPack order feature in the app, with 91% (39/43) indicating the order and tracking process was easy. Thematic data exploration further revealed important information for understanding (eg, items included in the package, use of mHealth platform to order package, and discreetness of the PartyPack box and order and delivery) and refining the logistical preferences (eg, using branded items and allowing customization during order).

    CONCLUSIONS: Our findings provide strong evidence of the usability and acceptability of a mHealth-delivered safer chemsex package as a potential sexual harm reduction tool among this underserved population. Replication in a study with a larger sample size to test the efficacy of the PartyPack is warranted.

  18. Tan KW, Tay L, Lim SH
    Singapore Med J, 1994 Jun;35(3):277-82.
    PMID: 7997904
    Methicillin resistant Staphylococcus aureus (MRSA) is a major infection control problem in many countries. There have been many reports of outbreaks in neonatal nurseries including, in our part of the world, Australia, Hong Kong and Malaysia. A recent outbreak of MRSA in the neonatal intensive care unit in the Kandang Kerbau Hospital, Singapore, presented us with the opportunity to study the clinical characteristics of the outbreak and the effects of infection control measures. Neonates admitted to the neonatal intensive care unit were studied over a 20-month period. They were all screened for nasal colonisation on admission and weekly thereafter. Infections were documented. Over this period there were altogether 2,576 admissions of which 85 infants had nasal colonisation with MRSA (3.3%) and 28 developed infections (1%). Although the majority of infants colonised by MRSA suffered no ill effects, 3 had septicaemia and 2 had septicaemia with osteomyelitis. There were no deaths. Standard infection control measures with barrier nursing and the use of mupirocin nasal ointment were ineffective, and control was achieved only after strict cohorting together with the use of mupirocin was instituted. This was done without additional costs to the department and without additional nurses or doctors.
  19. Moo CL, Yang SK, Osman MA, Yuswan MH, Loh JY, Lim WM, et al.
    Pol J Microbiol, 2020;69:1-6.
    PMID: 32162852 DOI: 10.33073/pjm-2020-007
    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to -3.98 mV, compared to untreated cells (-5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to –3.98 mV, compared to untreated cells (–5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

  20. Yap PS, Krishnan T, Chan KG, Lim SH
    J Microbiol Biotechnol, 2015 Aug;25(8):1299-306.
    PMID: 25381741 DOI: 10.4014/jmb.1407.07054
    This study aimed to investigate the mechanism of action of the cinnamon bark essential oil (CB), when used singly and also in combination with piperacillin, for its antimicrobial and synergistic activity against beta-lactamase TEM-1 plasmid-conferred Escherichia coli J53 R1. Viable count of this combination showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis on the stability of treated cultures for cell membrane permeability by CB when tested against sodium dodecyl sulfate revealed that the bacterial cell membrane was disrupted by the essential oils. Scanning electron microscopy observation and bacterial surface charge measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed reduction, indicating the possibility of the presence of quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%), and eugenol (6.57%) were the major components in the essential oil. From this study, CB has the potential to reverse E. coli J53 R1 resistance to piperacillin through two pathways; modification in the permeability of the outer membrane or bacterial QS inhibition.
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