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Fulltext Whole genome sequencing of methicillin-resistant Staphylococcus aureus clinical isolates from Terengganu, Malaysia, indicates the predominance of the EMRSA-15 (ST22-SCCmec IV) clone

Che Hamzah AM, Chew CH, Al-Trad EI, Puah SM, Chua KH, A Rahman NI, et al.

Sci Rep, 2024 Feb 12;14(1):3485.
PMID: 38347106 DOI: 10.1038/s41598-024-54182-x

Despite the importance of methicillin-resistant Staphylococcus aureus (MRSA) as a priority nosocomial pathogen, the genome sequences of Malaysian MRSA isolates are currently limited to a small pool of samples. Here, we present the genome sequence analyses of 88 clinical MRSA isolates obtained from the main tertiary hospital in Terengganu, Malaysia in 2016-2020, to obtain in-depth insights into their characteristics. The EMRSA-15 (ST22-SCCmec IV) clone of the clonal complex 22 (CC22) lineage was predominant with a total of 61 (69.3%) isolates. Earlier reports from other Malaysian hospitals indicated the predominance of the ST239 clone, but only two (2.3%) isolates were identified in this study. Two Indian-origin clones, the Bengal Bay clone ST772-SCCmec V (n = 2) and ST672 (n = 10) were also detected, with most of the ST672 isolates obtained in 2020 (n = 7). Two new STs were found, with one isolate each, and were designated ST7879 and ST7883. From the core genome phylogenetic tree, the HSNZ MRSA isolates could be grouped into seven clades. Antimicrobial phenotype-genotype concordance was high (> 95%), indicating the accuracy of WGS in predicting most resistances. Majority of the MRSA isolates were found to harbor more than 10 virulence genes, demonstrating their pathogenic nature.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus*
Fulltext Targeting the hard to reach: challenges and novel strategies in the treatment of intracellular bacterial infections

Kamaruzzaman NF, Kendall S, Good L

Br J Pharmacol, 2017 Jul;174(14):2225-2236.
PMID: 27925153 DOI: 10.1111/bph.13664

Infectious diseases continue to threaten human and animal health and welfare globally, impacting millions of lives and causing substantial economic loss. The use of antibacterials has been only partially successful in reducing disease impact. Bacterial cells are inherently resilient, and the therapy challenge is increased by the development of antibacterial resistance, the formation of biofilms and the ability of certain clinically important pathogens to invade and localize within host cells. Invasion into host cells provides protection from both antibacterials and the host immune system. Poor delivery of antibacterials into host cells causes inadequate bacterial clearance, resulting in chronic and unresolved infections. In this review, we discuss the challenges associated with existing antibacterial therapies with a focus on intracellular pathogens. We consider the requirements for successful treatment of intracellular infections and novel platforms currently under development. Finally, we discuss novel strategies to improve drug penetration into host cells. As an example, we discuss our recent demonstration that the cell penetrating cationic polymer polyhexamethylene biguanide has antibacterial activity against intracellular Staphylococcus aureus.
LINKED ARTICLES: This article is part of a themed section on Drug Metabolism and Antibiotic Resistance in Micro-organisms. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.14/issuetoc.

Matched MeSH terms: Staphylococcus aureus/drug effects
Fulltext Green Synthesized Silver Nanoparticles Immobilized on Activated Carbon Nanoparticles: Antibacterial Activity Enhancement Study and Its Application on Textiles Fabrics

Wibawa PJ, Nur M, Asy'ari M, Wijanarka W, Susanto H, Sutanto H, et al.

Molecules, 2021 Jun 22;26(13).
PMID: 34206375 DOI: 10.3390/molecules26133790

This research aimed to enhance the antibacterial activity of silver nanoparticles (AgNPs) synthesized from silver nitrate (AgNO3) using aloe vera extract. It was performed by means of incorporating AgNPs on an activated carbon nanoparticle (ACNPs) under ultrasonic agitation (40 kHz, 2 × 50 watt) for 30 min in an aqueous colloidal medium. The successful AgNPs synthesis was clarified with both Ultraviolet-Visible (UV-Vis) and Fourier Transform Infrared (FTIR) spectrophotometers. The successful AgNPs-ACNPs incorporation and its particle size analysis was performed using Transmission Electron Microscope (TEM). The brown color suspension generation and UV-Vis's spectra maximum wavelength at around 480 nm confirmed the existence of AgNPs. The particle sizes of the produced AgNPs were about 5 to 10 nm in the majority number, which collectively surrounded the aloe vera extract secondary metabolites formed core-shell like nanostructure of 8.20 ± 2.05 nm in average size, while ACNPs themselves were about 20.10 ± 1.52 nm in average size formed particles cluster, and 48.00 ± 8.37 nm in average size as stacking of other particles. The antibacterial activity of the synthesized AgNPs and AgNPs-immobilized ACNPs was 57.58% and 63.64%, respectively (for E. coli); 61.25%, and 93.49%, respectively (for S. aureus). In addition, when the AgNPs-immobilized ACNPs material was coated on the cotton and polyester fabrics, the antibacterial activity of the materials changed, becoming 19.23% (cotton; E. coli), 31.73% (polyester; E. coli), 13.36% (cotton; S. aureus), 21.15% (polyester; S. aureus).

Matched MeSH terms: Staphylococcus aureus/growth & development*
Synthesis and characterization of marine seagrass (Cymodocea serrulata) mediated titanium dioxide nanoparticles for antibacterial, antibiofilm and antioxidant properties

Narayanan M, Srinivasan S, Gnanasekaran C, Ramachandran G, Chelliah CK, Rajivgandhi G, et al.

Microb Pathog, 2024 Apr;189:106595.
PMID: 38387848 DOI: 10.1016/j.micpath.2024.106595

Cymodocea serrulata mediated titanium dioxide nanoparticles (TiO2 NPs) were successfully synthesized. The XRD pattern and FTIR spectra demonstrated the crystalline structure of TiO2 NPs and the presence of phenols, flavonoids and alkaloids in the extract. Further SEM revealed that TiO2 NPs has uniform structure and spherical in shape with their size ranged from 58 to 117 nm. Antibacterial activity of TiO2 NPs against methicillin-resistant Staphylococcus aureus (MRSA) and Vibrio cholerae (V. cholerae), provided the zone of inhibition of 33.9 ± 1.7 and 36.3 ± 1.9 mm, respectively at 100 μg/mL concentration. MIC of TiO2 NPs against MRSA and V. cholerae showed 84% and 87% inhibition at 180 μg/mL and 160 μg/mL respectively. Subsequently, the sub-MIC of V. cholerae demonstrated minimal or no impact on bacterial growth at concentration of 42.5 μg/mL concentration. In addition, TiO2 NPs exhibited their ability to inhibit the biofilm forming V. cholerae which caused distinct morphological and intercellular damages analysed using CLSM and TEM. The antioxidant properties of TiO2 NPs were demonstrated through TAA and DPPH assays and exposed its scavenging activity with IC50 value of 36.42 and 68.85 μg/mL which denotes its valuable antioxidant properties with potential health benefits. Importantly, the brine shrimp based lethality experiment yielded a low cytotoxic effect with 13% mortality at 100 μg/mL. In conclusion, the multifaceted attributes of C. serrulata mediated TiO2 NPs encompassed the antibacterial, antioxidant and anti-biofilm inhibition effects with low cytotoxicity in nature were highlighted in this study and proved the bioderived TiO2 NPs could be used as a promising agent for biomedical applications.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus*
Fulltext Porcine placenta hydrolysate as an alternate functional food ingredient: In vitro antioxidant and antibacterial assessments

Laosam P, Panpipat W, Yusakul G, Cheong LZ, Chaijan M

PLoS One, 2021;16(10):e0258445.
PMID: 34695136 DOI: 10.1371/journal.pone.0258445

The production of bioactive peptides from animal-based raw materials highly depends on enzymatic hydrolysis. Porcine placenta is an underutilized biomass in Thailand's pig farms, yet it is still a source of proteins and beneficial compounds. Porcine placenta could be used as a protein substrate for the production of enzymatic hydrolysate, which could be employed as a functional food ingredient in the future. The goal of this study was to enzymatically produce porcine placenta hydrolysates (PPH) using three commercial enzymes (Alcalase, Flavouzyme, and papain) and evaluate their in vitro antioxidant and antibacterial activity. The degree of hydrolysis (DH) increased as the enzyme load and hydrolysis time increased, but the DH was governed by the enzyme class. The maximum DH was found after using 10% enzyme for 20 min of hydrolysis (36.60%, 31.40%, and 29.81% for Alcalase, Flavouzyme, and papain). Depending on the enzyme type and DH, peptides of various sizes (0.40-323.56 kDa) were detected in all PPH. PPH created with Alcalase had an excellent reducing capacity and metal chelating ability (p < 0.05), whereas PPH made with Flavourzyme and Papain had higher DPPH• and ABTS•+ inhibitory activities (p < 0.05). Papain-derived PPH also had a strong antibacterial effect against Staphylococcus aureus and Escherichia coli, with clear zone values of 17.20 mm and 14.00 mm, respectively (p < 0.05). When PPH was transported via a gastrointestinal tract model system, its antioxidative characteristics were altered. PPH's properties and bioactivities were thus influenced by the enzyme type, enzyme concentration, and hydrolysis time used. Therefore, PPH produced from porcine placenta can be categorized as an antioxidant and antibacterial alternative.

Matched MeSH terms: Staphylococcus aureus/drug effects
Fulltext Efficient Synthesis, Structural Characterization, Antibacterial Assessment, ADME-Tox Analysis, Molecular Docking and Molecular Dynamics Simulations of New Functionalized Isoxazoles

Arzine A, Hadni H, Boujdi K, Chebbac K, Barghady N, Rhazi Y, et al.

Molecules, 2024 Jul 17;29(14).
PMID: 39064944 DOI: 10.3390/molecules29143366

This work describes the synthesis, characterization, and in vitro and in silico evaluation of the biological activity of new functionalized isoxazole derivatives. The structures of all new compounds were analyzed by IR and NMR spectroscopy. The structures of 4c and 4f were further confirmed by single crystal X-ray and their compositions unambiguously determined by mass spectrometry (MS). The antibacterial effect of the isoxazoles was assessed in vitro against Escherichia coli, Bacillus subtilis, and Staphylococcusaureus bacterial strains. Isoxazole 4a showed significant activity against E. coli and B. subtilis compared to the reference antibiotic drugs while 4d and 4f also exhibited some antibacterial effects. The molecular docking results indicate that the synthesized compounds exhibit strong interactions with the target proteins. Specifically, 4a displayed a better affinity for E. coli, S. aureus, and B. subtilis in comparison to the reference drugs. The molecular dynamics simulations performed on 4a strongly support the stability of the ligand-receptor complex when interacting with the active sites of proteins from E. coli, S. aureus, and B. subtilis. Lastly, the results of the Absorption, Distribution, Metabolism, Excretion and Toxicity Analysis (ADME-Tox) reveal that the molecules have promising pharmacokinetic properties, suggesting favorable druglike properties and potential therapeutic agents.

Matched MeSH terms: Staphylococcus aureus/drug effects
Enterotoxin production by Staphylococcus aureus strains isolated from humans, foods and animals in Malaysia

Lim YS, Jegathesan M, Koay AS

Southeast Asian J Trop Med Public Health, 1982 Mar;13(1):133-7.
PMID: 7112212

Enterotoxin production by strains of Staphylococcus aureus isolated from human, food and animal sources was investigated. Of the 130 isolates studied, 27 (20.8%) were found to be enterotoxigenic. The most common enterotoxin detected from human sources was enterotoxin C whereas enterotoxin B occurred more frequently in staphylococcal strains of food origin. The 2 enterotoxigenic strains, from animals isolated from a dog and a goat, produced enterotoxins A and C, respectively. Enterotoxin E was not detected alone from any of the enterotoxigenic strains studied, but occurred together with other enterotoxins. The need to detect enterotoxin in staphylococcal strains and in suspected foods for the confirmation of staphylococcal food poisoning is discussed.

Matched MeSH terms: Staphylococcus aureus/metabolism*
Enhancing refrigerated chicken breasts preservation: Novel composite hydrogels incorporated with antimicrobial peptides, bacterial cellulose, and polyvinyl alcohol

Si S, Huang X, Wang Q, Manickam S, Zhao D, Liu Y

Int J Biol Macromol, 2024 Nov;281(Pt 4):136505.
PMID: 39395516 DOI: 10.1016/j.ijbiomac.2024.136505

Microbial contamination annually leads to substantial food resource loss. Effective food packaging can mitigate food contamination and waste, yet conventional materials such as plastics often lack bacteriostatic activity. This study aimed to synthesise FengycinA-M3@bacterial cellulose@polyvinyl alcohol composite hydrogels via dual cross-linking with hydrogen and borate bonding, with the goal of enhancing antibacterial properties and prolonging the preservation period of refrigerated chicken breast. The composite hydrogel was subjected to comprehensive characterisation for structural, mechanical, water absorption, slow peptide release, antimicrobial capacity, biocompatibility, and chicken breast freshness preservation. The results showed that the composite hydrogel had a porous network structure and excellent gel elasticity and biocompatibility. It was effective in inhibiting Staphylococcus aureus and Escherichia coli, and prolonged the storage time of frozen chicken breast for up to 12 days. These findings emphasise the potential of hydrogel food packaging to prolong storage periods and its suitability for food industry applications due to ease of manufacture.

Matched MeSH terms: Staphylococcus aureus/drug effects
Prevalence, Microbial Etiology and Risk Factors Associated With Healthcare Associated Infections Among End Stage Renal Disease Patients on Renal Replacement Therapy

Abbasi SH, Aftab RA, Mei Lai PS, Lim SK, Nur Zainol Abidin R

J Pharm Pract, 2023 Oct;36(5):1142-1155.
PMID: 35466786 DOI: 10.1177/08971900221094269

End stage renal disease (ESRD) patients on renal replacement therapy (RRT) have an increased risk of morbidity and mortality due to healthcare associated infections (HCAIs). The aim of this study is to determine the prevalence, microbial etiology, and risk factors associated with HCAIs among ESRD patients on RRT. A multicenter, retrospective study was conducted from June to December 2019. ESRD patients with minimum of 6 months on RRT were included, while pregnant patients and patients <18 years were excluded. To reduce the risk of selection bias, all patients were randomly selected using a simple random sampling technique. The prevalence showing the proportion of patients that acquired HCAI since the initiation of dialysis until 2019 was calculated using the European patients' academy (EUPATI) formula. Risk factors were assessed using univariate and multivariate regression analysis. The prevalence of HCAI among ESRD patients was 174/400 (43.5%). Catheter related bloodstream infection (CRBSI) was the most common infection [64(36.8%)], followed by peritonitis [45(25.8%)] and pneumonia [37(21.2%)]. Out of 382 total pathogens identified, 204 (53.4%) were Gram positive and 162 (42.4%) were Gram negative. Both methicillin sensitive staphylococcus aureus (MSSA) and methicillin resistant staphylococcus aureus (MRSA) showed statistically significant associations (p<0.05) with CRBSI. Use of multiple accesses, increased blood sugar levels, low serum sodium levels and higher CRP concentration increased the occurrence of HCAIs. The burden of HCAIs among the patients undergoing RRT is high. Preventive strategies and optimum empirical therapy of antibiotics should be used to reduce the risk of these infections among ESRD patients.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus*
Fulltext Cellulose nanocrystals/ZnO as a bifunctional reinforcing nanocomposite for poly(vinyl alcohol)/chitosan blend films: fabrication, characterization and properties

Azizi S, Ahmad MB, Ibrahim NA, Hussein MZ, Namvar F

Int J Mol Sci, 2014 Jun 18;15(6):11040-53.
PMID: 24945313 DOI: 10.3390/ijms150611040

In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.

Matched MeSH terms: Staphylococcus aureus/drug effects
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.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/genetics*; Methicillin-Resistant Staphylococcus aureus/isolation & purification; Methicillin-Resistant Staphylococcus aureus/metabolism
Molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among veterinary students and personnel at a veterinary hospital in Malaysia

Aklilu E, Zunita Z, Hassan L, Cheng CH

Vet Microbiol, 2013 Jun 28;164(3-4):352-8.
PMID: 23523336 DOI: 10.1016/j.vetmic.2013.02.030

In this study, we report the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among veterinary students and personnel in Malaysia. Nasal and oral swabs were collected from 103 veterinary medicine students and 28 personnel from a veterinary hospital. Antibiotic sensitivity test (AST), minimum inhibitory concentration (MIC) test, and PCR amplifications of nucA and mecA gene were performed. Molecular characterization of the isolates was conducted using multilocus sequence typing (MLST), staphylococcal protein A gene (spa) typing, and pulsed-field gel electrophoresis (PFGE). Results from MLST show the presence of the pandemic and widespread MRSA clones, ST5 and ST59. Spa gene typing revealed spa type t267 which has a wide geographical distribution. A new spa type, t5697 was found in this study. Fingerprint analysis by using PFGE show heterogeneity of the isolates. These findings affirm the importance of MRSA in veterinary settings and underscore the need for further extensive research to devise contextual control and prevention strategies.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/classification; Methicillin-Resistant Staphylococcus aureus/drug effects; Methicillin-Resistant Staphylococcus aureus/genetics; Methicillin-Resistant Staphylococcus aureus/physiology*
Combined use of ribotyping, PFGE typing and IS431 typing in the discrimination of nosocomial strains of methicillin-resistant Staphylococcus aureus

Yoshida T, Kondo N, Hanifah YA, Hiramatsu K

Microbiol. Immunol., 1997;41(9):687-95.
PMID: 9343819

We have previously reported the phenotypic characterization of methicillin-resistant Staphylococcus aureus (MRSA) clinical strains isolated in Malaya University Hospital in the period 1987 to 1989 using antibiogram, coagulase typing, plasmid profiles, and phage typing. Here, we report the analysis of the same strains with three genotyping methods; ribotyping, pulsed-field gel electrophoresis (PFGE) typing, and IS431 typing (a restriction enzyme fragment length polymorphism analysis using an IS431 probe). Ribotyping could discriminate 46 clinical MRSA strains into 5 ribotypes, PFGE typing into 22 types, and IS431 typing into 15 types. Since the differences of the three genotyping patterns from strain to strain were quite independent from one another, the combined use of the three genotyping methods could discriminate 46 strains into 39 genotypes. Thus, the powerful discriminatory ability of the combination was demonstrated.

Matched MeSH terms: Staphylococcus aureus/classification*; Staphylococcus aureus/drug effects; Staphylococcus aureus/genetics; Staphylococcus aureus/isolation & purification
Antimicrobial resistance profiling and molecular typing of methicillin-resistant Staphylococcus aureus isolated from a Malaysian teaching hospital

Noordin A, Sapri HF, Mohamad Sani NA, Leong SK, Tan XE, Tan TL, et al.

J Med Microbiol, 2016 Dec;65(12):1476-1481.
PMID: 27902380 DOI: 10.1099/jmm.0.000387

The annual prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Malaysia has been estimated to be 30 % to 40 % of all S. aureus infections. Nevertheless, data on the antimicrobial resistance and genetic diversity of Malaysian MRSAs remain few. In 2009, we collected 318 MRSA strains from various wards of our teaching hospital located in Kuala Lumpur, the capital city of Malaysia, and performed antimicrobial susceptibility testing on these strains. The strains were then molecularly characterized via staphylococcal cassette chromosome (SCC) mec and virulence gene (cna, sea, seb, sec, sed, see, seg, seh, sei, eta, etb, Panton-Valentine leukocidin and toxic shock syndrome toxin-1) typing; a subset of 49 strains isolated from the intensive care unit was also typed using PFGE. Most strains were found to be resistant to ciprofloxacin (92.5 %), erythromycin (93.4 %) and gentamicin (86.8 %). The majority (72.0 %) of strains were found to harbour SCCmec type III-SCCmercury with the presence of ccrC, and carried the sea+cna gene combination (49.3 %), with cna as the most prevalent virulence gene (94.0 %) detected. We identified four PFGE clusters, with pulsotype C (n=19) as the dominant example in the intensive care unit, where this pulsotype was found to be associated with carriage of SCCmec type III and the sea gene (P=0.05 and P=0.02, respectively). In summary, the dominant MRSA circulating in our hospital in 2009 was a clone that was ciprofloxacin, erythromycin and gentamicin resistant, carried SCCmec type III-SCCmercury with ccrC and also harboured the sea+cna virulence genes. This clone also appears to be the dominant MRSA circulating in major hospitals in Kuala Lumpur.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/classification; Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/genetics*; Methicillin-Resistant Staphylococcus aureus/isolation & purification
Fulltext Phenotypic and genotypic characterization of methicillin-resistant Staphylococcus aureus (MRSA) isolated from dogs and cats at University Veterinary Hospital, Universiti Putra Malaysia

Aklilu E, Zunita Z, Hassan L, Chen HC

Trop Biomed, 2010 Dec;27(3):483-92.
PMID: 21399590

Methicillin-resistant Staphylococcus aureus (MRSA) is known to cause nosocomial infections and is now becoming an emerging problem in veterinary medicine. The objective of the study was to determine the presence of MRSA in 100 cats and dogs sampled between November 2007 and April 2008 at the University Veterinary Hospital, Universiti Putra Malaysia. MRSA was detected in 8% of pets sampled. Ten percent (5/50) and 6% (3/50) of the isolates were from dogs and cats, respectively. All MRSA isolates possessed the mecA gene and were found to be resistant to at least three antimicrobials with a minimum of Oxacillin MIC of 8 μg/mL. One isolate (CT04) had an extremely high MIC of >256 μg/mL. The MLST type ST59 found in this study have been reported earlier from Singapore and other countries as a strain from animal and community-associated MRSA respectively. Pulsed-field gel electrophoresis revealed five pulsotypes. Two isolates from cats (CT27 and CT33) and three isolates from dogs (DG16, DG20, and DG49) were respectively assigned to pulsotypes B and D. The study suggests that cats and dogs in Malaysia are potential reservoirs for MRSA.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/classification; Methicillin-Resistant Staphylococcus aureus/genetics; Methicillin-Resistant Staphylococcus aureus/isolation & purification*; Methicillin-Resistant Staphylococcus aureus/physiology
Transcriptome analysis of methicillin-resistant Staphylococcus aureus in response to stigmasterol and lupeol

Adnan SN, Ibrahim N, Yaacob WA

J Glob Antimicrob Resist, 2017 03;8:48-54.
PMID: 27992774 DOI: 10.1016/j.jgar.2016.10.006

OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen with multiple antibiotic resistance that causes morbidity and mortality worldwide. Multidrug-resistant (MDR) MRSA with increased resistance to currently available antibiotics has challenged the world to develop new therapeutic agents. Stigmasterol and lupeol, from the plant Phyllanthus columnaris, exhibit antibacterial activities against MRSA. The aim of this study was to utilise next-generation sequencing (NGS) to provide further insight into the novel transcriptional response of MRSA exposed to stigmasterol and lupeol.
METHODS: Time-kill analysis of one MRSA reference strain (ATCC 43300) and three clinical isolates (WM3, BM1 and KJ7) for both compounds was first performed to provide the bacteriostatic/bactericidal profile. Then, MRSA ATCC 43300 strain treated with both compounds was interrogated by NGS.
RESULTS: Both stigmasterol and lupeol possessed bacteriostatic properties against all MRSA tested; however, lupeol exhibited both bacteriostatic and bactericidal properties within the same minimum inhibitory concentration and minimum bactericidal concentration values against BM1 (12.5mg/mL). Transcriptome profiling of MRSA ATCC 43300 revealed significant modulation of gene expression with multiple desirable targets by both compounds, which caused a reduction in the translation processes leading to inhibition of protein synthesis and prevention of bacterial growth.
CONCLUSIONS: This study highlights the potential of both stigmasterol and lupeol as new promising anti-MRSA agents.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/genetics*; Methicillin-Resistant Staphylococcus aureus/growth & development; Methicillin-Resistant Staphylococcus aureus/metabolism*
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.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/classification*; Methicillin-Resistant Staphylococcus aureus/genetics; Methicillin-Resistant Staphylococcus aureus/immunology*; Methicillin-Resistant Staphylococcus aureus/pathogenicity
High prevalence of qacA/B carriage among clinical isolates of meticillin-resistant Staphylococcus aureus in Malaysia

Shamsudin MN, Alreshidi MA, Hamat RA, Alshrari AS, Atshan SS, Neela V

J Hosp Infect, 2012 Jul;81(3):206-8.
PMID: 22633074 DOI: 10.1016/j.jhin.2012.04.015

The minimum inhibitory concentrations (MICs) of 60 meticillin-resistant Staphylococcus aureus (MRSA) isolates from Malaysia to three antiseptic agents - benzalkonium chloride (BZT), benzethonium chloride (BAC) and chlorhexidine digluconate (CHG) - were determined. All isolates had MICs ranging from 0.5 to 2 mg/L. Antiseptic resistance genes qacA/B and smr were detected in 83.3% and 1.6% of the isolates, respectively. Carriage of qacA/B correlated with reduced susceptibility to CHG and BAC. This is the first report of the prevalence of qacA/B and smr gene carriage in Malaysian MRSA isolates, with a high frequency of qacA/B carriage. The presence of these antiseptic resistance genes and associated reduced susceptibility to antiseptic agents may have clinical implications.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/genetics; Methicillin-Resistant Staphylococcus aureus/isolation & purification; Methicillin-Resistant Staphylococcus aureus/metabolism
Fulltext Inhibitory effect of Duabanga grandiflora on MRSA biofilm formation via prevention of cell-surface attachment and PBP2a production

Santiago C, Lim KH, Loh HS, Ting KN

Molecules, 2015 Mar 10;20(3):4473-82.
PMID: 25764489 DOI: 10.3390/molecules20034473

Formation of biofilms is a major factor for nosocomial infections associated with methicillin-resistance Staphylococcus aureus (MRSA). This study was carried out to determine the ability of a fraction, F-10, derived from the plant Duabanga grandiflora to inhibit MRSA biofilm formation. Inhibition of biofilm production and microtiter attachment assays were employed to study the anti-biofilm activity of F-10, while latex agglutination test was performed to study the influence of F-10 on penicillin-binding protein 2a (PBP2a) level in MRSA biofilm. PBP2a is a protein that confers resistance to beta-lactam antibiotics. The results showed that, F-10 at minimum inhibitory concentration (MIC, 0.75 mg/mL) inhibited biofilm production by 66.10%; inhibited cell-surface attachment by more than 95%; and a reduced PBP2a level in the MRSA biofilm was observed. Although ampicilin was more effective in inhibiting biofilm production (MIC of 0.05 mg/mL, 84.49%) compared to F-10, the antibiotic was less effective in preventing cell-surface attachment. A higher level of PBP2a was detected in ampicillin-treated MRSA showing the development of further resistance in these colonies. This study has shown that F-10 possesses anti-biofilm activity, which can be attributed to its ability to reduce cell-surface attachment and attenuate the level of PBP2a that we postulated to play a crucial role in mediating biofilm formation.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/physiology*
Inhibition of Staphylococcus aureus by crude and fractionated extract from lactic acid bacteria

Wong CB, Khoo BY, Sasidharan S, Piyawattanametha W, Kim SH, Khemthongcharoen N, et al.

Benef Microbes, 2015 Mar;6(1):129-39.
PMID: 25213027 DOI: 10.3920/BM2014.0021

Increasing levels of antibiotic resistance by Staphylococcus aureus have posed a need to search for non-antibiotic alternatives. This study aimed to assess the inhibitory effects of crude and fractionated cell-free supernatants (CFS) of locally isolated lactic acid bacteria (LAB) against a clinical strain of S. aureus. A total of 42 LAB strains were isolated and identified from fresh vegetables, fresh fruits and fermented products prior to evaluation of inhibitory activities. CFS of LAB strains exhibiting a stronger inhibitive effect against S. aureus were fractionated into crude protein, polysaccharide and lipid fractions. Crude protein fractions showed greater inhibition against S. aureus compared to polysaccharide and lipid fractions, with a more prevalent effect from Lactobacillus plantarum 8513 and L. plantarum BT8513. Crude protein, polysaccharide and lipid fractions were also characterised with glycine, mannose and oleic acid being detected as the major component of each fraction, respectively. Scanning electron microscopy revealed roughed and wrinkled membrane morphology of S. aureus upon treatment with crude protein fractions of LAB, suggesting an inhibitory effect via the destruction of cellular membrane. This research illustrated the potential application of fractionated extracts from LAB to inhibit S. aureus for use in the food and health industry.

Matched MeSH terms: Staphylococcus aureus/drug effects*; Staphylococcus aureus/growth & development*

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