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Fulltext A study of primary drug resistance in pulmonary tuberculosis in west Malaysia 1984-1987

Jalleh RD, Kuppusamy I, Soshila R, Aziah AM, Faridza MY

Med J Malaysia, 1993 Jun;48(2):113-6.
PMID: 8350784

Eight hundred and fifty-six strains of Mycobacterium tuberculosis from previously untreated patients with pulmonary tuberculosis from various states in West Malaysia were studied during the period 1984 to 1987. All the strains were tested for in vitro susceptibility to the anti-tuberculosis drugs isoniazid (INH), streptomycin (SM), rifampicin (RMP) and ethambutol (ETB). One hundred and twenty-one of the isolates (14.18%) were resistant to 1 drug while 17 (1.97%) were resistant to 2 drugs. No strain was found to be resistant to more than 2 drugs. The prevalence of primary resistance to INH was 4.20%, SM was 7.59%, RMP was 0.95% and ETB was 1.44%. In 1.86% of isolates, resistance was noted to both INH and SM, while 0.11% were resistant to both RMP and ETB. There was no significant difference in distribution of resistant bacilli between the sexes (p > 0.01).

Matched MeSH terms: Microbial Sensitivity Tests
Occurrence of Vibrio cholerae 01 strains in Southeast Asia resistant to vibriostatic compound 0/129

Mahalingam S, Cheong YM, Kan SK, Pang T

Southeast Asian J. Trop. Med. Public Health, 1993 Dec;24(4):779-80.
PMID: 7939959
Matched MeSH terms: Microbial Sensitivity Tests
Conjugal transfer of antibiotic resistances and plasmids from Campylobacter jejuni clinical isolates

Ansary A, Radu S

FEMS Microbiol Lett, 1992 Mar 01;70(2):125-8.
PMID: 1587459

Six Campylobacter jejuni clinical isolates were examined for the occurrence of plasmids in association with antibiotic resistances as well as conjugal transfer. All the isolates were found to carry three similar plasmids of 78 kb, 12.6 kb and 3.3 kb in size. Multiple resistance to at least three of the antibiotics tested was observed with resistance to tetracycline most common. En bloc transfer of donor resistances at frequencies ranging from 10(-8) to 10(-4) were seen in all but one of the isolates during conjugation. The conjugal transfer of erythromycin, neomycin and streptomycin were observed to occur at frequencies similar to that of chloramphenicol, kanamycin and tetracycline. In isolate ABA94, three different antibiotic resistance phenotypes of the transconjugants were seen. In addition to en bloc transfer of the donor resistances, in approximately 10% of the transconjugants the streptomycin resistance was lost although these transconjugants carried the donor complement of three plasmids. In a further 1% of the transconjugants, resistance to kanamycin only was detected and these transconjugants did not carry any plasmids.

Matched MeSH terms: Microbial Sensitivity Tests
Conjugal transfer of plasmids and antibiotic resistance among Escherichia coli isolated from animals in a rural area in Sarawak (Malaysia)

Son R, Rusu G, Karim MI

J Appl Microbiol, 1997 Feb;82(2):240-4.
PMID: 12452600

Thirty-six strains of Escherichia coli isolated from animals in Bario, a remote area in Sarawak, Malaysia, were examined for presence of plasmid DNA and their susceptibility to nine antimicrobial agents. Of the total 36 isolates, five bovine and six canine isolates were found to contain plasmid DNA ranging in sizes from 2.6 to 70 kilobases. All were susceptible to chloramphenicol, erythromycin, gentamicin, nalidixic acid and neomycin but resistance to ampicillin (47%), erythromycin (19%), streptomycin (25%) and tetracycline (11%) was observed. Resistance was associated with carriage of a 47 kb (SC98), 70 kb, (SC133) and 56 and 4.6 kb (SC119) plasmids which were transmissible to the Escherichia coli K12 recipient. It is concluded that animals form a potential reservoir of R plasmids carrying E. coli in the study area.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Tetracycline-resistant vibrio cholerae El Tor

Hassan H, Teh A

Med J Malaysia, 1993 Mar;48(1):95-6.
PMID: 8341181

http://www.e-mjm.org/1993/v48n1/Vibrio_Cholerae_El_Tor.pdf

Matched MeSH terms: Microbial Sensitivity Tests
Serotype prevalence and antibiotic susceptibility of Shigella strains isolated in Malaysia during 1980 and 1981

Jegathesan M

J Diarrhoeal Dis Res, 1984 Jun;2(2):102-4.
PMID: 6501820
Matched MeSH terms: Microbial Sensitivity Tests
Conjugal transfer of multiple antibiotic resistance from hospital isolates of Klebsiella to Escherichia coli

Koh CL, Lim ME, Wong YH

Southeast Asian J. Trop. Med. Public Health, 1983 Sep;14(3):336-40.
PMID: 6362015

Six independent isolates of Klebsiella from hospital environmental sources in Malaysia were found to be resistant to at least ampicillin, carbenicillin, cefoperazone, chloramphenicol, gentamicin and tetracycline. On the basis of their antibiograms, they were divided into four antibiogroups. They transferred all or part of their multiple antibiotic resistance traits to E. coli by conjugation. The results suggest that these Klebsiella strains harbour self-transmissible R plasmids. The significance of these findings are discussed.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Plasmid-mediated transferable chloramphenicol and tetracycline resistance in Salmonella typhi (Vi phage type 25) isolated in Peninsular Malaysia

Koh CL, Lim ME, Wong YH

Med J Malaysia, 1983 Dec;38(4):320-4.
PMID: 6599991

A clinical isolate of Salmonella typhi (Vi phage type 25), resistant to chloramphenicol, streptomycin and tetracycline, was examined for the presence of R plasmids. Results from conjugation, agarose gel electrophoresis and transformation experiments indicated that it harboured a single large self-transmissible R plasmid which coded for both the chloramphenicol and tetracycline resistance traits.

Matched MeSH terms: Microbial Sensitivity Tests
A new flavonoid and sulphur-containing amides from Glycosmis chlorosperma

Rahmani M, Leng KW, Ismail HB, Hin TY, Sukari MA, Ali AM, et al.

Nat Prod Res, 2004 Feb;18(1):85-8.
PMID: 14974620

A new flavonoid, dihydroglychalcone-A, was isolated from the leaves extract of Glycosmis chlorosperma in addition to two known sulphur-containing amides, dambullin and gerambullin. The structure of the new compound was assigned as 2'-hydroxy-4,6'-dimethoxy-3',4'-(2",2"-dimethylpyrano)dihydrochalcone. The extract of the leaves was also found to exhibit antimicrobial and cytotoxic activities.

Matched MeSH terms: Microbial Sensitivity Tests
Susceptibility of Mycobacterium tuberculosis to isoniazid and its derivative, 1-isonicotinyl-2-nonanoyl hydrazine: investigation at cellular level

Mohamad S, Ibrahim P, Sadikun A

Tuberculosis (Edinb), 2004;84(1-2):56-62.
PMID: 14670346

In this study, the susceptibility of Mycobacterium tuberculosis to isoniazid (INH) was compared with its derivative, 1-isonicotinyl-2-nonanoyl hydrazine (INH-C9), prepared synthetically. The minimum inhibitory concentration (MIC) of the drugs was determined using the 1% proportion method. INH-C9 was found to lower the MIC of INH from 0.05 to 0.025 microg/ml. Further studies on the effects of INH and INH-C9 on M. tuberculosis were assessed by exposing the cells to the above at the MIC level. M. tuberculosis cells grown on Middlebrook 7H10 agar were harvested at different stages of their growth cycle (initial stage, 24 and 72 h), exposed to the MICs of INH and INH-C9, and stained with acid-fast staining. The observations were made for a week. The cellular morphologies and staining characteristics were examined using a Brightfield microscope. The result indicated cells only at the initial stage of growth were most susceptible to the drugs resulting in the loss of acid-fastness and intact cellular morphology in the majority of cells.

Matched MeSH terms: Microbial Sensitivity Tests
The pattern of bacteriological cultures in a state laboratory

Lim Swee Eng, Bin Mohamed Hussain AH

Med J Malaysia, 1973 Dec;28(2):103-8.
PMID: 4276266
Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Antibiogram Profiles and Risk Factors for Multidrug Resistance of Salmonella enterica Recovered from Village Chickens (Gallus gallus domesticus Linnaeus) and Other Environmental Sources in the Central and Southern Peninsular Malaysia

Mohammed Jajere S, Hassan L, Zakaria Z, Abu J, Abdul Aziz S

Antibiotics (Basel), 2020 Oct 15;9(10).
PMID: 33076451 DOI: 10.3390/antibiotics9100701

The emergence of multidrug resistance (MDR), including colistin resistance, among Enterobacteriaceae recovered from food animals poses a serious public health threat because of the potential transmission of these resistant variants to humans along the food chain. Village chickens or Ayam Kampung are free-range birds and are preferred by a growing number of consumers who consider these chickens to be organic and more wholesome. The current study investigates the antibiogram profiles of Salmonella isolates recovered from village chicken flocks in South-central Peninsular Malaysia. A total of 34 isolates belonging to eight serotypes isolated from village chickens were screened for resistance towards antimicrobials including colistin according to the WHO and OIE recommendations of critical antibiotics. S. Weltevreden accounted for 20.6% of total isolates, followed by serovars Typhimurium and Agona (17.6%). The majority of isolates (73.5%) demonstrated resistance to one or more antimicrobials. Eight isolates (23.5%) were resistant to ≥3 antimicrobial classes. Colistin resistance (minimum inhibitory concentrations: 4-16 mg/L) was detected among five isolates (14.7%), including S. Weltevreden, S. Albany, S. Typhimurium, and Salmonella spp. Univariable analysis of risk factors likely to influence the occurrence of MDR Salmonella revealed that the flock size, poultry production system, and use of antibiotics in the farm were not significantly (p > 0.05) associated with MDR Salmonella. The current study highlights that MDR Salmonella occur at a lower level in village chickens compared to that found in live commercial chickens. However, MDR remains a problem even among free-range chickens with minimal exposure to antibiotics.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Antibacterial activities of green silver nanoparticles-Strobilanthes crispus (AgNP-SC) against clinically important bacteria

Rohazila Mohamad Hanafiah, Siti Nor Asma Musa, Siti Aisyah Abd Ghafar

Malaysian Journal of Medicine and Health Sciences, 2019;15(108):40-40.
MyJurnal

Introduction: Silver nanoparticles has been proven to be an effective agent for antimicrobial efficacy against bacte-ria, viruses and other eukaryotic microorganisms. Green synthesis is one of the methods that has been developed to synthesize silver nanoparticles in environmentally-friendly conditions. It uses plant extracts as reducing and capping agents. Besides act as reducing and capping agents, bioactives such as phenolic compounds may bind to silver nanoparticles and enhance its medicinal properties. Strobilanthes crispus is a Malaysian native plant. Previous stud-ies had shown that S. crispus contains polyphenols, catechins, alkaloids, caffeine, tannins and vitamins. Therefore, the aim of this study is to determine antibacterial activities of silver nanoparticles-Strobilanthes crispus (AgNP-SC) against clinically important pathogens such as Escherichia coli, Pseudomonas aeruginosa and Streptococcus mutans. Methods: The disc diffusion assay (DDA) was performed to investigate the inhibition zone of AgNps-Sc towards E. coli, P. aeruginosa and S. mutans. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) was used to determine bactericidal/bacteriostatic profile of AgNP- SC against E. coli, P. aeruginosa and S. mu-tans. Results: AgNP-SC (40mg/mL) shows the greatest inhibition properties (12.67±0.6mm) against S. mutans when compared to Strobilanthes crispus leaves extract (6.0±0.001mm) and blank silver nanoparticles (6.0±0.001mm). MIC values for AgNP-SC against S. mutans and E. coli were at 0.625 mg/mL and 1.25 mg/mL, respectively. Whereas the MIC value of AgNP- SC against P. aeruginosa was at 2.5 mg/mL. MBC values of AgNP-SC against E. coli, P. aerugino-sa and S. mutans were at 1.25, 2.5 mg/mL respectively. Results are concentration-dependent, with higher concentra-tion demonstrating better inhibition property. Conclusion: It can be concluded that AgNP-SC possesses bactericidal properties against S. mutans, E. coli and P. aeruginosa.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext The relationship between bacterial sources and genotype to the antimicrobial resistance pattern of Burkholderia pseudomallei

Sadiq MA, Hassan L, Aziz SA, Zakaria Z, Musa HI, Amin MM

Vet World, 2018 Nov;11(10):1404-1408.
PMID: 30532493 DOI: 10.14202/vetworld.2018.1404-1408

Background: Melioidosis is a fatal emerging infectious disease of both man and animal caused by bacteria Burkholderia pseudomallei. Variations were suggested to have existed among the different B. pseudomallei clinical strains/genotypes which may implicate bacterial susceptibility and resistance toward antibiotics.
Aim: This study was designed to determine whether the phenotypic antibiotic resistance pattern of B. pseudomallei is associated with the source of isolates and the genotype.
Materials and Methods: A collection of 111 B. pseudomallei isolates from veterinary cases of melioidosis and the environments (soil and water) were obtained from stock cultures of previous studies and were phylogenetically characterized by multilocus sequence typing (ST). The susceptibility to five antibiotics, namely meropenem (MEM), imipenem, ceftazidime (CAZ), cotrimoxazole (SXT), and co-amoxiclav (AMC), recommended in both acute and eradication phases of melioidosis treatment were tested using minimum inhibitory concentration antibiotics susceptibility test.
Results: Majority of isolates were susceptible to all antibiotics tested while few resistant strains to MEM, SXT, CAZ, and AMC were observed. Statistically significant association was found between resistance to MEM and the veterinary clinical isolates (p<0.05). The likelihood of resistance to MEM was significantly higher among the novel ST 1130 isolates found in veterinary cases as compared to others.
Conclusion: The resistance to MEM and SXT appeared to be higher among veterinary isolates, and the novel ST 1130 was more likely to be resistant to MEM as compared to others.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Genomic and RT-qPCR analysis of trimethoprim-sulfamethoxazole and meropenem resistance in Burkholderia pseudomallei clinical isolates

Schnetterle M, Gorgé O, Nolent F, Boughammoura A, Sarilar V, Vigier C, et al.

PLoS Negl Trop Dis, 2021 Feb;15(2):e0008913.
PMID: 33592059 DOI: 10.1371/journal.pntd.0008913

BACKGROUND: Melioidosis is an endemic disease in southeast Asia and northern Australia caused by the saprophytic bacteria Burkholderia pseudomallei, with a high mortality rate. The clinical presentation is multifaceted, with symptoms ranging from acute septicemia to multiple chronic abscesses. Here, we report a chronic case of melioidosis in a patient who lived in Malaysia in the 70s and was suspected of contracting tuberculosis. Approximately 40 years later, in 2014, he was diagnosed with pauci-symptomatic melioidosis during a routine examination. Four strains were isolated from a single sample. They showed divergent morphotypes and divergent antibiotic susceptibility, with some strains showing resistance to trimethoprim-sulfamethoxazole and fluoroquinolones. In 2016, clinical samples were still positive for B. pseudomallei, and only one type of strain, showing atypical resistance to meropenem, was isolated.
PRINCIPAL FINDINGS: We performed whole genome sequencing and RT-qPCR analysis on the strains isolated during this study to gain further insights into their differences. We thus identified two types of resistance mechanisms in these clinical strains. The first one was an adaptive and transient mechanism that disappeared during the course of laboratory sub-cultures; the second was a mutation in the efflux pump regulator amrR, associated with the overexpression of the related transporter.
CONCLUSION: The development of such mechanisms may have a clinical impact on antibiotic treatment. Indeed, their transient nature could lead to an undiagnosed resistance. Efflux overexpression due to mutation leads to an important multiple resistance, reducing the effectiveness of antibiotics during treatment.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext In Vitro Efficacy of Flomoxef against Extended-Spectrum Beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Associated with Urinary Tract Infections in Malaysia

Ngoi ST, Teh CSJ, Chong CW, Abdul Jabar K, Tan SC, Yu LH, et al.

Antibiotics (Basel), 2021 Feb 11;10(2).
PMID: 33670224 DOI: 10.3390/antibiotics10020181

The increasing prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has greatly affected the clinical efficacy of β-lactam antibiotics in the management of urinary tract infections (UTIs). The limited treatment options have resulted in the increased use of carbapenem. However, flomoxef could be a potential carbapenem-sparing strategy for UTIs caused by ESBL-producers. Here, we compared the in vitro susceptibility of UTI-associated ESBL-producers to flomoxef and established β-lactam antibiotics. Fifty Escherichia coli and Klebsiella pneumoniae strains isolated from urine samples were subjected to broth microdilution assay, and the presence of ESBL genes was detected by polymerase chain reactions. High rates of resistance to amoxicillin-clavulanate (76-80%), ticarcillin-clavulanate (58-76%), and piperacillin-tazobactam (48-50%) were observed, indicated by high minimum inhibitory concentration (MIC) values (32 µg/mL to 128 µg/mL) for both species. The ESBL genes blaCTX-M and blaTEM were detected in both E. coli (58% and 54%, respectively) and K. pneumoniae (88% and 74%, respectively), whereas blaSHV was found only in K. pneumoniae (94%). Carbapenems remained as the most effective antibiotics against ESBL-producing E. coli and K. pneumoniae associated with UTIs, followed by flomoxef and cephamycins. In conclusion, flomoxef may be a potential alternative to carbapenem for UTIs caused by ESBL-producers in Malaysia.

Matched MeSH terms: Microbial Sensitivity Tests
Molecular analysis of ciprofloxacin resistance among non-typhoidal Salmonella with reduced susceptibility to ciprofloxacin isolated from patients at a tertiary care hospital in Kuala Lumpur, Malaysia

Karunakaran R, Tay ST, Rahim FF, Lim BB, Puthucheary SD

Jpn J Infect Dis, 2014;67(3):157-62.
PMID: 24858603

We investigated the prevalence of non-typhoidal Salmonella (NTS) with "reduced susceptibility to ciprofloxacin" (RS-Cip) (minimum inhibitory concentration [MIC], 0.12-1.0 μg/mL) as well as their resistance genes in 75 NTS isolates (53 from stool, 21 from blood, and 1 from urine) from patients at a tertiary care Malaysian hospital between January and December 2009. RS-Cip was detected in 24/75 (32.0%) isolates. Using the ciprofloxacin MIC interpretive criteria for Salmonella in the Clinical and Laboratory Standards Institute 2013 guidelines, 51/75 (68.0%) isolates were found to be sensitive, 22/75 (29.3%) were intermediate, and 2/75 (2.7%) were resistant to ciprofloxacin. The 24 isolates that were intermediate or resistant to ciprofloxacin were the same isolates categorized as having RS-Cip. Among the 23 tested isolates with RS-Cip, the qnrS gene was detected in 17/23 (73.9%) and single gyrA mutations were detected in 6/23 (26.1%) (Asp87Tyr [n = 3], Asp87Asn [n = 2], and Ser83Phe [n = 1]). A parC (Thr57Ser) mutation was detected in 13/23 (56.5%) isolates, coexisting with either a qnrS gene or a gyrA mutation. The high incidence of the qnrS gene among isolates with RS-Cip needs to be monitored because qnr genes can spread via plasmids and aid in the emergence of increased resistance levels.

Matched MeSH terms: Microbial Sensitivity Tests
Group B Streptococcus infection: epidemiology, serotypes, and antimicrobial susceptibility of selected isolates in the population beyond infancy (excluding females with genital tract- and pregnancy-related isolates) at the University Malaya Medical Centre, Kuala Lumpur

Karunakaran R, Raja NS, Hafeez A, Puthucheary SD

Jpn J Infect Dis, 2009 May;62(3):192-4.
PMID: 19468178

Group B Streptococcus (GBS) infection was studied in 49 patients collected at convenience (convenience sampling), excluding infants and women with genital tract- and pregnancy-related isolates, according to the availability of stocked isolates and easy accessibility to epidemiological data. The data were examined both prospectively and retrospectively from 2003-2005 at a tertiary-level multidisciplinary hospital in Kuala Lumpur, Malaysia. Skin and soft-tissue infections in 35 patients (71.4%) were the most common clinical presentation, while diabetes mellitus was the most common underlying condition (35 patients, 71.4%). All GBS isolates were sensitive to penicillin, and most isolates tested were sensitive to erythromycin (97.7%). Serotyping of 45 GBS isolates using a commercial serotyping kit revealed that the most common serotype was Ia (22.2%), followed by VI (17.8%), III and V (13.3% each). Others included Ib, II, IV, VIII, and VII; 13.3% were nontypeable. The findings of this pilot study are limited by the small sample size, the sampling method and the possibility that the cases are not wholly representative of the University Malaya Medical Centre population. Further studies from our hospital with larger numbers and using probabilistic sampling techniques are required to confirm the relatively high occurrence of serotype VI (the second most common serotype) in the population studied.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Evaluation of a Multidisciplinary Antimicrobial Stewardship Program in a Saudi Critical Care Unit: A Quasi-Experimental Study

Haseeb A, Faidah HS, Al-Gethamy M, Iqbal MS, Barnawi AM, Elahe SS, et al.

Front Pharmacol, 2020;11:570238.
PMID: 33776750 DOI: 10.3389/fphar.2020.570238

Background: Antimicrobial stewardship programs (ASPs) are collaborative efforts to optimize antimicrobial use in healthcare institutions through evidence-based quality improvement strategies. With regard to critically ill patients, appropriate antimicrobial usage is of significance, and any delay in therapy increases their risk of mortality. Therefore, the implementation of structured multidisciplinary ASPs in critical care settings is of the utmost importance to promote the judicious use of antimicrobials. Methods: This quasi-experimental study evaluating a multidisciplinary ASP in a 20-bed critical care setting was conducted from January 1, 2016 to July 31, 2017. Outcomes were compared nine months before and after ASP implementation. The national antimicrobial stewardship toolkit by Ministry of health was reviewed and the hospital antibiotic prescribing policy was accordingly modified. The antimicrobial stewardship algorithm (Start Smart and Then Focus) and an ASP toolkit were distributed to all intensive care unit staff. Prospective audit and feedback, in addition to prescribing forms for common infectious diseases and education, were the primary antimicrobial strategies. Results: We found that the mean total monthly antimicrobial consumption measured as defined daily dose per 100 bed days was reduced by 25% (742.86 vs. 555.33; p = 0.110) compared to 7% in the control condition (tracer medications) (35.35 vs. 38.10; p = 0.735). Interestingly, there was a negative impact on cost in the post-intervention phase. Interestingly, the use of intravenous ceftriaxone measured as defined daily dose per 100 bed days was decreased by 82% (94.32 vs. 16.68; p = 0.008), whereas oral levofloxacin use was increased by 84% (26.75 vs. 172.29; p = 0.008) in the intensive care unit. Conclusion: Overall, involvement of higher administration in multidisciplinary ASP committees, daily audit and feedback by clinical pharmacists and physicians with infectious disease training, continuous educational activities about antimicrobial use and resistance, use of local antimicrobial prescribing guidelines based on up-to-date antibiogram, and support from the intensive care team can optimize antibiotic use in Saudi healthcare institutions.

Matched MeSH terms: Microbial Sensitivity Tests
Fulltext Biodiscovery of Potential Antibacterial Diagnostic Metabolites from the Endolichenic Fungus Xylaria venustula Using LC-MS-Based Metabolomics

Santiago KAA, Edrada-Ebel R, Dela Cruz TEE, Cheow YL, Ting ASY

Biology (Basel), 2021 Mar 04;10(3).
PMID: 33806264 DOI: 10.3390/biology10030191

Three species of the lichen Usnea (U. baileyi (Stirt.) Zahlbr., U. bismolliuscula Zahlbr. and U. pectinata Stirt.) and nine associated endolichenic fungi (ELF) were evaluated using a metabolomics approach. All investigated lichen crude extracts afforded antibacterial activity against Staphylococcus aureus (minimum inhibitory concentration (MIC): 0.0625 mg/mL), but none was observed against Escherichia coli, while the ELF extract Xylaria venustula was found to be the most active against S. aureus (MIC: 2.5 mg/mL) and E. coli (MIC: 5 mg/mL). X. venustula was fractionated and tested for to determine its antibacterial activity. Fractions XvFr1 to 5 displayed bioactivities against both test bacteria. Selected crude extracts and fractions were subjected to metabolomics analyses using high-resolution LC-MS. Multivariate analyses showed the presence of five secondary metabolites unique to bioactive fractions XvFr1 to 3, which were identified as responsible for the antibacterial activity of X. venustula. The p-values of these metabolites were at the margin of significance level, with methyl xylariate C (P_60) being the most significant. However, their high variable importance of projection (VIP) scores (>5) suggest these metabolites are potential diagnostic metabolites for X. venustula for "dual" bioactivity against S. aureus and E. coli. The statistical models also showed the distinctiveness of metabolites produced by lichens and ELF, thus supporting our hypotheses of ELF functionality similar to plant endophytes.

Matched MeSH terms: Microbial Sensitivity Tests

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