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Dielectrophoresis microbial characterization and isolation of Staphylococcus aureus based on optimum crossover frequency

Rozaini AZA, Abdulhameed A, Deivasigamani R, Nadzreen N, Zin NM, Kayani AA, et al.

Electrophoresis, 2023 Aug;44(15-16):1220-1233.
PMID: 37259263 DOI: 10.1002/elps.202200276

Characterization of antibiotic-resistant bacteria is a significant concern that persists for the rapid classification and analysis of the bacteria. A technology that utilizes the manipulation of antibiotic-resistant bacteria is key to solving the significant threat of these pathogenic bacteria by rapid characterization profile. Dielectrophoresis (DEP) can differentiate between antibiotic-resistant and susceptible bacteria based on their physical structure and polarization properties. In this work, the DEP response of two Gram-positive bacteria, namely, Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-susceptible S. aureus (MSSA), was investigated and simulated. The DEP characterization was experimentally observed on the bacteria influenced by oxacillin and vancomycin antibiotics. MSSA control without antibiotics has crossover frequencies ( f x 0 ${f_{x0}}$ ) from 6 to 8 MHz, whereas MRSA control is from 2 to 3 MHz. The f x 0 ${f_{x0}}$ changed when bacteria were exposed to the antibiotic. As for MSSA, the f x 0 ${f_{x0}}$ decreased to 3.35 MHz compared to f x 0 ${f_{x0}}$ MSSA control without antibiotics, MRSA, f x 0 ${f_{x0}}$ increased to 7 MHz when compared to MRSA control. The changes in the DEP response of MSSA and MRSA with and without antibiotics were theoretically proven using MyDEP and COMSOL simulation and experimentally based on the modification to the bacteria cell walls. Thus, the DEP response can be employed as a label-free detectable method to sense and differentiate between resistant and susceptible strains with different antibiotic profiles. The developed method can be implemented on a single platform to analyze and identify bacteria for rapid, scalable, and accurate characterization.

Matched MeSH terms: Staphylococcus aureus; Methicillin-Resistant Staphylococcus aureus*
Fulltext A Review of Staphylococcal Cassette Chromosome mec (SCCmec) Types in Coagulase-Negative Staphylococci (CoNS) Species

Saber H, Jasni AS, Jamaluddin TZMT, Ibrahim R

Malays J Med Sci, 2017 Oct;24(5):7-18.
PMID: 29386968 MyJurnal DOI: 10.21315/mjms2017.24.5.2

Coagulase-negative staphylococci (CoNS) are considered low pathogenic organisms. However, they are progressively causing more serious infections with time because they have adapted well to various antibiotics owing to their ability to form biofilms. Few studies have been conducted on CoNS in both, hospital and community-acquired settings, especially in Malaysia. Thus, it is important to study their species and gene distributions. A mobile genetic element, staphylococcal cassette chromosome mec (SCCmec), plays an important role in staphylococci pathogenesis. Among CoNS, SCCmec has been studied less frequently than Staphylococcus aureus (coagulase-positive staphylococci). A recent study (8) conducted in Malaysia successfully detected SCCmec type I to VIII as well as several new combination patterns in CoNS species, particularly Staphylococcus epidermidis. However, data are still limited, and further research is warranted. This paper provides a review on SCCmec types among CoNS species.

Matched MeSH terms: Staphylococcus; Staphylococcus aureus; Staphylococcus epidermidis
Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

Salim MM, Malek NANN

Mater Sci Eng C Mater Biol Appl, 2016 Feb;59:70-77.
PMID: 26652350 DOI: 10.1016/j.msec.2015.09.099

The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading.

Matched MeSH terms: Staphylococcus aureus/growth & development*
Fulltext Draft Genome Sequence of Methicillin-Resistant Staphylococcus aureus KT/Y21, a Sequence Type 772 (ST772) Strain Isolated from a Pediatric Blood Sample in Terengganu, Malaysia

Suhaili Z, Lean SS, Yahya A, Mohd Desa MN, Ali AM, Yeo CC

Genome Announc, 2014;2(2).
PMID: 24723714 DOI: 10.1128/genomeA.00271-14

Here, we report the draft genome sequence of a methicillin-resistant Staphylococcus aureus (MRSA) strain, KT/Y21, isolated from a blood sample of a pediatric patient. This strain belongs to sequence type 772 (ST772), harbors the staphylococcal cassette chromosome mec element (SCCmec) type V, and is positive for the Panton-Valentine leukocidin (PVL) pathogenic determinant.

Matched MeSH terms: Staphylococcus; Methicillin-Resistant Staphylococcus aureus
Short communication: prevalence and antibiotic resistance of Staphylococcus aureus isolated from bovine clinical mastitis

Jamali H, Radmehr B, Ismail S

J Dairy Sci, 2014;97(4):2226-30.
PMID: 24534509 DOI: 10.3168/jds.2013-7509

The aims of this study were to determine the prevalence and antibiotic resistance of Staphylococcus aureus isolated from bovine clinical mastitis in Varamin, Tehran Province, Iran. All of the isolated Staph. aureus were identified by morphology and culture and confirmed using the API Staph identification system (bioMérieux, Marcy-l'Étoile, France). Antibiotic resistance genes were detected by PCR with oligonucleotide primers specific for each gene. Staphylococcus aureus was recovered from 43 of 207 (20.1%) bovine clinical milk samples. Using disk diffusion, methicillin-resistant Staph. aureus was detected in 5 of 43 (11.6%) samples. The pathogen showed high resistance against penicillin G (86%) and tetracycline (76.7%). The blaZ (penicillin) (86%), tetM (tetracycline), and ermC (erythromycin) genes (39.5% each) were the most prevalent antibiotic resistance genes. The findings of this study are useful for designing specific control programs for bovine clinical mastitis caused by Staph. aureus in this region of Iran.

Matched MeSH terms: Staphylococcus aureus/drug effects*; Staphylococcus aureus/genetics; Staphylococcus aureus/metabolism; Methicillin-Resistant Staphylococcus aureus/drug effects; Methicillin-Resistant Staphylococcus aureus/genetics; Methicillin-Resistant Staphylococcus aureus/metabolism
Fulltext Inhibition of penicillin-binding protein 2a (PBP2a) in methicillin resistant Staphylococcus aureus (MRSA) by combination of ampicillin and a bioactive fraction from Duabanga grandiflora

Santiago C, Pang EL, Lim KH, Loh HS, Ting KN

BMC Complement Altern Med, 2015;15:178.
PMID: 26060128 DOI: 10.1186/s12906-015-0699-z

The inhibition of penicillin-binding protein 2a (PBP2a) is a promising solution in overcoming resistance of methicillin resistance Staphylococcus aureus (MRSA). A potential approach in achieving this is by combining natural product with currently available antibiotics to restore the activity as well as to amplify the therapeutic ability of the drugs. We studied inhibition effects of a bioactive fraction, F-10 (isolated from the leaves of Duabanga grandiflora) alone and in combination with a beta-lactam drug, ampicillin on MRSA growth and expression of PBP2a. Additionally, phytochemical analysis was conducted on F-10 to identify the classes of phytochemicals present.

Matched MeSH terms: Staphylococcus aureus/drug effects; Staphylococcus aureus/growth & development; Staphylococcus aureus/metabolism; Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/growth & development; Methicillin-Resistant Staphylococcus aureus/metabolism
Fulltext The occurrence of enterotoxigenic strains of Staphylococcus aureus in foods

Lim YS, Jegathesan M, Koay AS, Kang SH

Med J Malaysia, 1983 Mar;38(1):27-30.
PMID: 6633330

Enterotoxin production by strains of Staphylococcus aureus isolated from foods unconnected with outbreaks offood poisoning was investigated. Twenty-three percent of 217 strains examined produced enterotoxins A, B, C, D or E. Enterotoxin C was found to occur most frequently. Enterotoxin A was not detected alone from any of the strains examined, but occurred together with other enterotoxins. The overall number of strains isolated from raw foods which produced one or more enterotoxins was higher than that for cooked foods. Antibiotic sensitivities were unrelated to enterotoxin production and no correlation could be found between methicillin resistance and enterotoxigenicity.

Matched MeSH terms: Staphylococcus aureus/metabolism*
The sensitivity of staphylococci to antibiotics

Puthucheary SD, Chen ST, Dugdale AE

Med J Malaya, 1972 Jun;26(4):262-5.
PMID: 5069415
Matched MeSH terms: Staphylococcus/drug effects*
In vitro anti-bacterial and time kill evaluation of binuclear tricyclohexylphosphanesilver(I) dithiocarbamates, {Cy3PAg(S2CNRR')}2

Tan YJ, Tan YS, Yeo CI, Chew J, Tiekink ERT

J Inorg Biochem, 2019 03;192:107-118.
PMID: 30640150 DOI: 10.1016/j.jinorgbio.2018.12.017

Four binuclear phosphanesilver(I) dithiocarbamates, {cyclohexyl3PAg(S2CNRR')}2 for R = R' = Et (1), CH2CH2 (2), CH2CH2OH (3) and R = Me, R' = CH2CH2OH (4) have been synthesised and characterised by spectroscopy and crystallography, and feature tri-connective, μ2-bridging dithiocarbamate ligands and distorted tetrahedral geometries based on PS3 donor sets. The compounds were evaluated for anti-bacterial activity against a total of 12 clinically important pathogens. Based on minimum inhibitory concentration (MIC) and cell viability tests (human embryonic kidney cells, HEK 293), 1-4 are specifically active against Gram-positive bacteria while demonstrating low toxicity; 3 and 4 are active against methicillin resistant S. aureus (MRSA). Across the series, 4 was most effective and was more active than the standard anti-biotic chloramphenicol. Time kill assays reveal 1-4 to exhibit both time- and concentration-dependent pharmacokinetics against susceptible bacteria. Compound 4 demonstrates rapid (within 2 h) bactericidal activity at 1 and 2 × MIC to reach a maximum decrease of 5.2 log10 CFU/mL against S. aureus (MRSA).

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/growth & development*
Fulltext Screening and detection of heterogenous vancomycin intermediate Staphylococcus aureus in Hospital Kuala Lumpur Malaysia, using the glycopeptide resistance detection Etest and population analysis profiling

Ramli SR, Neoh HM, Aziz MN, Hussin S

Infect Dis Rep, 2012 Jan 2;4(1):e20.
PMID: 24470927 DOI: 10.4081/idr.2012.e20

In a 3-month study done in Hospital Kuala Lumpur (HKL), 7 out of 320 methicillin resistant Staphylococcus aureus isolates were confirmed as heterogeneous vancomycin intermediate S. aureus (hVISA) using the glycopeptide resistance detection e-test and population analysis, giving a prevalence rate of 2.19%. This is the first report of hVISA in Malaysia.

Matched MeSH terms: Staphylococcus aureus; Methicillin-Resistant Staphylococcus aureus
The impact of gallium content on degradation, bioactivity, and antibacterial potency of zinc borate bioactive glass

Rahimnejad Yazdi A, Torkan L, Stone W, Towler MR

J Biomed Mater Res B Appl Biomater, 2018 Jan;106(1):367-376.
PMID: 28152268 DOI: 10.1002/jbm.b.33856

Zinc borate glasses with increasing gallium content (0, 2.5, 5, 10, and 15 Wt % Ga) were synthesized and their degradation, bioactivity in simulated body fluid (SBF), and antibacterial properties were investigated. ICP measurements showed that increased gallium content in the glass resulted in increased gallium ion release and decreased release of other ions. Degradability declined with the addition of gallium, indicating the formation of more symmetric BO3 units with three bridging oxygens and asymmetric BO3 units with two bridging oxygens in the glass network as the gallium content in the series increased. The formation of amorphous CaP on the glass surface after 24 h of incubation in SBF was confirmed by SEM, XRD, and FTIR analyses. Finally, antibacterial evaluation of the glasses using the agar disc-diffusion method demonstrated that the addition of gallium increased the antibacterial potency of the glasses against P. aeruginosa (Gram-negative) while decreasing it against S. epidermidis (Gram-positive); considering the ion release trends, this indicates that the gallium ion is responsible for the glasses' antibacterial behavior against P. aeruginosa while the zinc ion controls the antibacterial activity against S. epidermidis. The statistical significance of the observed trends in the measurements were confirmed by applying the Kruskal-Wallis H Test. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 367-376, 2018.

Matched MeSH terms: Staphylococcus epidermidis/growth & development*
Synthesis of Iron Oxide@Pt Core-Shell Nanoparticles for Reductive Conversion of Cr(VI) to Cr(III) and Antibacterial Studies

Sivaranjan K, Santhanalakshmi J, Panneer DS, Vivekananthan S, Sagadevan S, Johan MRB, et al.

J Nanosci Nanotechnol, 2020 02 01;20(2):918-923.
PMID: 31383087 DOI: 10.1166/jnn.2020.16895

Herein, we report the facile synthesis of Iron oxide@Pt core-shell nanoparticles (NPs) by facile two step synthesis process. The first step follows the growth of iron oxide nanoparticle by thermal decomposition process while the second step deals with the formation of iron oxide@Pt core-shell nanoparticles by the chemical reduction method. The synthesized core-shell nanoparticles were characterized by several techniques and used for the catalytic reductive translation of Cr(VI) to Cr(III) in the presence of formic acid by a UV-vis spectrophotometer. The UV photo-spectrometer analysis confirmed the conversion efficiency from 12% to as high as 98.8% at the end of 30 minutes. Thus, the presence of Iron oxide @Pt core-shell nanoparticles (NPs) can be effectively used as a catalyst for the reducion of Cr(VI) to Cr(III) ions. Additionally, antibacterial studies were performed for the prepared core-shell nanoparticles against two bacterial strains, i.e., gram (+ve) Staphylococcus Aureus (S. Aureus) and gram (-ve) Escherichia Coli (E. Coli).

Matched MeSH terms: Staphylococcus aureus*
In situ functionalizing calcium phosphate biomaterials with curcumin for the prevention of bacterial biofilm infections

Lee WH, Rohanizadeh R, Loo CY

Colloids Surf B Biointerfaces, 2021 Oct;206:111938.
PMID: 34198233 DOI: 10.1016/j.colsurfb.2021.111938

This study developed a novel bioactive bone substitute (hydroxyapatite, HA) with improved anti-biofilm activity by functionalizing with curcumin (anti-biofilm compound) which provide sufficient flux of curcumin concentration for 14 days. The released curcumin acts to inhibit biofilm formation and control the number of viable planktonic cells simultaneously. To prepare curcumin-functionalized HA, different concentrations of curcumin (up to 3% w/v) were added simultaneously during the precipitation process of HA. The highest loading (50 mg/g HA) of curcumin onto HA was achieved with 2% w/v of curcumin. Physicochemical characterizations of curcumin-functionalized HA composites revealed that curcumin was successfully incorporated onto HA. Curcumin was sustainably released over 14 days, while higher curcumin release was observed in acidic condition (pH 4.4) compared to physiological (pH 7.4). The cytotoxicity assays revealed that no significant difference on bone cells growth on curcumin-functionalized HA and non-functionalized HA. Curcumin-functionalized HA was effective to inhibit bacterial cell attachment and subsequent biofilm maturation stages. The anti-biofilm effect was stronger against Staphylococcus aureus compared to Pseudomonas aeruginosa. The curcumin-functionalized HA composite significantly delayed the maturation of S. aureus compared to non-functionalized HA in which microcolonies of cells only begin to appear at 96 h. Up to 3.0 log reduction in colony forming unit (CFU)/mL of planktonic cells was noted at 24 h of incubation for both microorganisms. Thus, in this study we have suggested that curcumin loaded HA could be an alternative antimicrobial agent to control the risk of infections in post-surgical implants.

Matched MeSH terms: Staphylococcus aureus*
Fulltext Staphylococcus aureus nasal carriage in medical students of Universiti Teknologi MARA

Mohd Zain Z, Johari MF, Mohd Husin NS, Rozman NS, Ab Rashid A, Bahanuddin L, et al.

Journal of Clinical and Health Sciences, 2017;2(1):29-34.
MyJurnal

Introduction: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage and detection of S. aureus leukotoxins among medical students of Universiti Teknologi MARA. Methods: Both sides of the anterior nares of 136 volunteers, comprising 68 preclinical and 68 clinical medical students, were swabbed and immediately cultured onto mannitol salt agar for growth of S. aureus. Standard microbiological techniques were conducted to identify and confirm the S. aureus colonies and susceptibility test against oxacillin were conducted by using Kirby-Bauer method to determine their resistance to methicillin. Polymerase chain reaction was performed for detection of leukotoxins, i.e., Panton-Valentine Leukocidin (PVL) and -haemolysin genes. Results: Nineteen students (14%) consisting of 10 preclinical (14.7%) and 9 clinical (13.2%) were nasal carriers of S. aureus. However, none of the S. aureus isolates were MRSA. No PVL gene was detected but eight of them were positive for -haemolysin gene. Conclusion: There were no MRSA nasal carriers among the medical students, but a low prevalence of S. aureus nasal carriers was detected. These carriers do not pose as high risk because none of the strains of S. aureus possess both the -haemolysin toxin and the PVL toxin that are associated with tissue necrosis.

Matched MeSH terms: Staphylococcus aureus*
Staphylococcal cassette chromosome mec (SCCmec) and characterization of the attachment site (attB) of methicillin resistant Staphylococcus aureus (MRSA) and methicillin susceptible Staphylococcus aureus (MSSA) isolates

Bitrus AA, Zunita Z, Khairani-Bejo S, Othman S, Ahmad Nadzir NA

Microb Pathog, 2018 Oct;123:323-329.
PMID: 30053600 DOI: 10.1016/j.micpath.2018.07.033

This study was designed to screen for SCCmec types and to characterize the attachment site (attB) and universal insertion site (orfX) of SCCmec in a collection of 27 isolates (n = 11) methicillin resistant S. aureus and (n = 16) methicillin susceptible S. aureus isolates in Malaysia. Screening of SCCmec types and characterization of the attachment site was carried out using PCR amplification and Sanger's sequencing method. The result showed that a large proportion of the MRSA isolates carried SCCmec type III 7/11 (63%). Three isolates 3/11 (27%) and 1/11 (9.0%) carried SCCmec type II and IVd respectively. Amplification of the universal insertion site of the SCCmec (orfX) and attachment site (attB) showed that all 16 S. aureus isolates were positive for the orfX gene, while only 7 were positive for the attB gene. Phylogenetic diversity showed that the isolates clustered around strains with features similar to a community acquired MRSA. In conclusion, a high carriage rate of SCCmec type III was observed. The result also showed that all the S. aureus isolates have the orfX structure; however, not all isolates possesses the attB site on the 3' end of the orfX region.

Matched MeSH terms: Staphylococcus aureus; Methicillin-Resistant Staphylococcus aureus
Fulltext Molecular detection of bacterial endosymbionts in acanthamoeba spp.: a preliminary study

Faizah, M. H., Anisah, N., Yusof, S., Noraina, A. R., Adibah, M. R.

Medicine & Health, 2017;12(2):286-292.
MyJurnal

Acanthamoeba spp. merupakan ameba hidup bebas yang biasa ditemui
di persekitaran. Ia merupakan agen penyebab keratitis Acanthamoeba (AK)
dan ensefalitis ameba bergranuloma (GAE). Ameba ini juga mampu menjadi
perumah kepada pelbagai bakteria termasuklah yang bersifat patogenik seperti
Mycobacterium, Legionella dan Staphylococcus aureus rintang metisilin (MRSA).
Berdasarkan maklumat ini, satu kajian dijalankan untuk mengesan kehadiran tiga
bakteria endosimbion berkepentingan perubatan di dalam Acanthamoeba spp. yang
telah dipencilkan dari bolong penghawa dingin yang terdapat di wad and dewan
bedah di Pusat Perubatan Universiti Kebangsaan Malaysia. Kehadiran bakteria
endosimbion ini disaring menggunakan pasangan primer khusus bagi setiap genus
menggunakan reaksi rantai polimerase (PCR) konvensional dan disahkan dengan
analisis penjujukan. Dua puluh sembilan (80.56%) pencilan Acanthamoeba spp.
didapati mengandungi bakteria endosimbion patogenik yang disasarkan dengan
sekurang-kurangnya satu genus bakteria bagi setiap pencilan. Mycobacterium
(82.76 %) adalah bakteria yang paling banyak dikesan, diikuti dengan Legionella sp.
(65.52 %) dan Pseudomonas spp. (62.07 %). Tiada bakteria MRSA dikesan daripada
mana-mana pencilan dalam kajian ini. Dua endosimbion Mycobacterium yang
dikenalpasti telah dikelompokkan ke dalam strain Mycobacterium tuberculosis.
Kami membuat kesimpulan bahawa, kebanyakan Acanthamoeba berpotensi untuk
menjadi perumah bagi pelbagai bakteria patogenik, namun implikasi interaksi ini
terhadap patogenisiti kedua-dua organisma masih kurang jelas dan memerlukan
penyelidikan yang lebih lanjut.

Matched MeSH terms: Staphylococcus aureus; Methicillin-Resistant Staphylococcus aureus
Fulltext Identification of Escherichia spp. strains in street-vended beverages and associated preparation surfaces using 16S rRNA analysis

Chong, S. Y., Rao, P. V., Soon, J. M.

International Food Research Journal, 2017;24(4):1811-1818.
MyJurnal

Street-vended beverages are commonly prepared by mechanical extraction of the pulp, usually
unpasteurised and requires multiple handling steps. Foodborne pathogens transmitted via skin of
street vendors or via faecal-oral route may contaminate the preparation surfaces and beverages.
The aim of this study is to identify Escherichia spp. strains of street-vended beverages and their
associated preparation surfaces using 16s rRNA analysis. The hygienic practice of vendors was represented by Staphylococcus spp. analysis and Staphylococcus aureus is not detected in beverages and associated preparation surfaces. A total of 80 samples (18 beverages, 15 swab
samples and 47 direct film samples) were collected followed by enumeration of microbial load.
Polymerase Chain Reaction (PCR) amplification and 16S ribosomal ribonucleic acid (rRNA)
sequencing were carried out. Results of 16S rRNA sequence analysis indicated that three gram-negative isolates were identified as Escherichia coli RM9387 (Accession no. CP009104.1),
Escherichia coli c164 (Accession no. JQ781646.1) and Escherichia fergusonii E10 (Accession no. KJ626264.1) with similarity value of 99% respectively.

Matched MeSH terms: Staphylococcus; Staphylococcus aureus
Effect of natural antibacterial clays against single biofilm formation by Staphylococcus aureus and Salmonella Typhimurium bacteria on a stainless-steel surface

Wan Omar WH, Mahyudin NA, Azmi NN, Mahmud Ab Rashid NK, Ismail R, Mohd Yusoff MHY, et al.

Int J Food Microbiol, 2023 Jun 02;394:110184.
PMID: 36996693 DOI: 10.1016/j.ijfoodmicro.2023.110184

Staphylococcus aureus and Salmonella Typhimurium have a propensity to develop biofilms on food contact surfaces, such as stainless-steel, that persist despite rigorous cleaning and sanitizing procedures. Since both bacterial species pose a significant public health risk within the food chain, improved anti-biofilm measures are needed. This study examined the potential of clays as antibacterial and anti-biofilm agents against these two pathogens on appropriate contact surfaces. Natural soil was processed to yield leachates and suspensions of both untreated and treated clays. Soil particle size, pH, cation-exchange capacity, and metal ions were characterized to assess their importance in bacterial killing. Initial antibacterial screening was performed on nine distinct types of natural Malaysian soil using a disk diffusion assay. Untreated leachate from Kuala Gula and Kuala Kangsar clays were found to inhibit S. aureus (7.75 ± 0.25 mm) and Salmonella Typhimurium (11.85 ± 1.63 mm), respectively. The treated Kuala Gula suspension (50.0 and 25.0 %) reduced S. aureus biofilms by 4.4 and 4.2 log at 24 and 6 h, respectively, while treated Kuala Kangsar suspension (12.5 %) by a 4.16 log reduction at 6 h. Although less effective, the treated Kuala Gula leachate (50.0 %) was effective in removing Salmonella Typhimurium biofilm with a decrease of >3 log in 24 h. In contrast to Kuala Kangsar clays, the treated Kuala Gula clays contained a much higher soluble metal content, especially Al (301.05 ± 0.45 ppm), Fe (691.83 ± 4.80 ppm) and Mg (88.44 ± 0.47 ppm). Elimination of S. aureus biofilms correlated with the presence of Fe, Cu, Pb, Ni, Mn and Zn irrespective of the pH of the leachate. Our findings demonstrate that a treated suspension is the most effective for eradication of S. aureus biofilms with a potential as a sanitizer-tolerant, natural antibacterial against biofilms for applications in the food industry.

Matched MeSH terms: Staphylococcus aureus*
Evaluation of the impact of COVID-19 pandemic on hospital-acquired infections in a tertiary hospital in Malaysia

Ismaeil R, Nahas ARF, Kamarudin NB, Abubakar U, Mat-Nor MB, Mohamed MHN

BMC Infect Dis, 2023 Nov 09;23(1):779.
PMID: 37946158 DOI: 10.1186/s12879-023-08770-3

BACKGROUND: Infection prevention measures are the gold standard for preventing the spread of hospital-acquired infections (HAIs). COVID-19 pandemic caused major disruptions in infection prevention measures, and this has implications on the rate of HAIs. This study assessed the impact of COVID-19 pandemic on the rate and the types of HAIs at Sultan Ahmed Shah Hospital.
METHOD: This is a retrospective cohort study that compared the rate of HAIs from April to October 2019 (pre COVID period) and April to October 2020 (during COVID period). Data was collected through the review of patients' electronic medical records.
RESULTS: There were a total of 578 patients included in the selected wards during the pre- and during the pandemic. Thirty-nine episodes (12.1%) of HAIs were report in the pre COVID period and 29 (11.3%) during COVID-19. In both periods, hospital-acquired pneumonia (HAP) was the most frequent HAI among the patients. There was a rise in catheter-associated bloodstream infections (CLABSI) (0.8%) and ventilator associated pneumonia (VAP) (1.1%) during the COVID-19 period. The most common bacteria were methicillin-resistant Staphylococcus aureus (MRSA) (28.2%) and Enterococcus faecalis (17.9%) in the Pre COVID-19 period, and Pseudomonas aeruginosa (27.6%) and Stenotrophomonas maltophilia (6.9%) during COVID-19.
CONCLUSION: Our research concluded that the rates of HAIs during the COVID-19 pandemic were not significantly impacted by the improved in-hospital infection prevention efforts to control the pandemic. There is need for further efforts to promote adherence to preventive practices.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus*
Tea Polyphenols Inhibit the Activity and Toxicity of Staphylococcus aureus by Destroying Cell Membranes and Accumulating Reactive Oxygen Species

Zhong W, Tang M, Xie Y, Huang X, Liu Y

Foodborne Pathog Dis, 2023 Jul;20(7):294-302.
PMID: 37347934 DOI: 10.1089/fpd.2022.0085

Staphylococcus aureus can cause bacterial food intoxication and seriously affect human health. Tea polyphenols (TP) are a kind of natural, safe, and broad-spectrum bacteriostatic substances, with a wide range of bacteriostatic effects. In the study, we explored the possible bacteriostatic mode of TP. The minimum inhibitory concentration of TP against S. aureus was 64 μg/mL. Protein, DNA, and K+ leak experiments, fluorescence microscopy, and transmission electron microscopy suggested that TP disrupt cell membranes, leading to intracellular component loss. By studying the effect of TP on the toxicity of S. aureus, it was found that the expression levels of two toxin genes, coa and spa, were downregulated by 2.37 and 32.6, respectively. Furthermore, after treatment with TP, a large number of reactive oxygen species (ROS) were propagated and released, leading to oxidative stress in cells. We speculated that the bacteriostatic mechanism of TP may be through the destruction of the cell membrane and ROS-mediated oxidative stress. Meanwhile, the hemolysis activity proved the safety of TP. Our results suggested that TP may be a potential antimicrobial agent for food.

Matched MeSH terms: Staphylococcus aureus*

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