Hesperidin inhibits biofilm formation, virulence and staphyloxanthin synthesis in methicillin resistant Staphylococcus aureus by targeting SarA and CrtM: An in vitro and in silico approach

Methicillin resistant Staphylococcus aureus is considered the multidrug resistant bacterium due to developing biofilm formation associated with antimicrobial resistance mechanisms. Therefore, inhibition of biofilm formation is an alternative therapeutic action to control MRSA infections. The present study revealed the non-antibacterial biofilm inhibitory potential of hesperidin against ATCC strain and clinical isolates of S. aureus. In addition, hesperidin treatment significantly impedes lipase, hemolysin, autolysin, autoaggregation and staphyloxanthin production. Reductions of staphyloxanthin production possibly increase the MRSA susceptibility rate to H2O2 oxidative stress condition. In gene expression study revealed the hesperidin treatment downregulated the biofilm-associated gene (sarA), polysaccharide intracellular adhesion gene (icaA and icaD), autolysin (altA), fibronectin-binding protein (fnbA and fnbB) and staphyloxanthin production (crtM). Molecular docking analysis predicted the ability of hesperidin to interact with SarA and CrtM proteins involved in biofilm formation and staphyloxanthin production in MRSA.

The Effect of Benzyl Isothiocyanate On The Expression of Genes Encoding NADH Oxidase And Fibronectin-Binding Protein In Oral Streptococcal Biofilms

Background: Recent studies have shown that antibiotic treatment results in up- or down regulation of several virulence-associated genes. The genes encoding NADH oxidase (nox) and fibronectin-binding protein (fbp) are known to play important roles in biofilms of some oral bacterial species. The objective was to study the effect of benzyl isothiocyanate (BITC), an antimicrobial agent from Miswak plant, on the expression of nox and fbp genes in some oral streptococci.Methods: Bacterial strains were grown as biofilms in brucella broth. The crystal violet stained biofilms were quantified by optical density measurements at 590 nm. The biofilms were treated with an antimicrobial agent (BITC) for 2 h and fold change in mRNA expression of nox and fbp genes in BITC treated selected oral streptococci was measured by comparative ∆∆Ct method on Real-Time PCR machine.Results: The highest amount of biofilm mass was produced by A. defectiva, followed by S. gordonii, S. mutans, G. elegans and G. adiacens. Upon treatment with BITC, S. gordonii biofilms showed highest mRNA expression for both fbp and nox genes. Mean (SE) folds increase in the expression of nox mRNA: S. gordonii 2 (0.30), followed by S. mutans 1.25 (0.18), A. defectiva 1.03 (0.09), G. adiacens 0.7 (0.03). Similarly for fbp, folds increase in mRNA expression was: S. gordonii 2.65 (0.03), followed by A. defectiva 2.09 (0.60), G. elegans 1.61 (0.40), S. mutans 1.57 (0.20), and G. adiacens 0.58 (0.06). G. elegans mRNA levels for nox were extremely low (0.006-fold). Conclusion: BITC treatment of the biofilms caused an upregulation of biofilm-associated genes fbp and nox genes in most of the tested species suggesting the significance of these genes in biofilm lifestyle of these oral bacteria. Increased expression of nox and fbp genes in the biofilm lifestyle of these species needs further investigation to understand if it contributes to antimicrobial resistance.

Molecular Investigation of Fibronectin-Binding Protein Genes and Capacity of Biofilm Production in Staphylococcus Aureus Isolated From Clinical Samples

Biofilm production increases Staphylococcus aureus resistance to antibiotics and also host defense mechanisms. The current study aims to evaluate the biofilm formation by S. aureus and to determine the prevalence of fibronectin-binding protein genes, also its correlation with drug resistance. In this study, 100 clinical isolates of S. aureus were collected. The antibiotic susceptibility pattern of the isolates was evaluated by the disk agar diffusion method. The ability of biofilm formation in the studied isolates was also determined by microplate colorimetric assay. Then, all isolates were screened by polymerase chain reaction for the fnbA and fnbB genes. Out of 100 clinical isolates of S. aureus, the highest and lowest antibiotic resistance rates were against penicillin (94%) and vancomycin (6%). Thirty-two cases were found to be multi-drug resistant (MDR) among the all strains. The ability of biofilm production was observed in 89% of the isolates. The PCR results showed that the prevalence of fnbA and fnbB genes were 91% and 17%, respectively. Moreover, 100% and 21.8% of the MDR strains harbored the fnbA and fnbB genes respectively. The ability to form biofilm in MDR isolates of S. aureus is more than non-MDR isolates, especially fnbA positive ones. As the bacteria in the biofilm are difficult to kill by antibiotics, attention to the removal or control of the biofilm production seems to be necessary.

The giant Staphylococcus epidermidis surface protein Embp binds selectively to fibrillated fibronectin through a Velcro-like mechanism

Staphylococcus epidermidis is a major cause of implant-associated infections. It attaches to implants via adsorbed host proteins, and one prominent adhesin is the fibronectin-binding protein Embp. This study aims to determine how S. epidermidis can attach to surfaces via adsorbed fibronectin, when fibronectin is also abundant in solution. We hypothesize that Embp interacts selectively with adsorbed fibronectin if adsorption introduces a conformational change. We produced a model system in which Fn adsorbed in either globular or fibrillated conformation. Embp-mediated attachment occurred exclusively to fibrillated Fn, and involved subdomain F3 12th-14th, which is buried in globular Fn. Single-molecule force spectroscopy revealed a Velcro-like interaction, as a single of the 60 Fn-binding repeats interacted weakly, while 15 FG-repeats attached strongly with the fibrillated ligand. This mechanism enables selective and strong attachment to immobilized Fn via a single surface protein: a mechanism that proved particularly beneficial for attachment under high flow conditions.

Gangrenous mastitis in sheep caused by multidrug-resistant Staphylococcus haemolyticus

ABSTRACT: Mastitis is a multifactorial disease and considered one of the most critical problems in the dairy industry worldwide. The condition is characterized by reduced milk and several abnormalities in the mammary gland. This study aimed to report an outbreak of gangrenous mastitis caused by multidrug-resistant Staphylococcus haemolyticus in a Santa Inês sheep herd. Eighteen sheep were affected, and five of them with severe clinical pictures were examined. The clinical and pathological picture were variable and characterized by apathy, anorexia, emaciation, opaque and brittle hair, apparent and congested episcleral vessels, and hyperthermia. These ewes had enlarged, firm, and painful mammary glands. Macroscopically, these lesions consisted of severe gangrenous mastitis, and microscopically, the primary lesions consisted of necrosis, thrombosis, and fibrosis of the mammary parenchyma. Milk samples from one of the five severely affected ewes were collected and cultured under aerobic or microaerophilic incubation at 37°C for 24 hours on sheep blood agar. The obtained colonies were then submitted to MALDI-TOF for speciation. The colonies were also submitted to an antimicrobial susceptibility test, genotyping of virulence factors and resistance genes were also performed. The isolates showed antimicrobial multiresistance since they were resistant to seven out of 13 tested antibiotics. The isolates were also positive for two staphylococcal enterotoxigenic genes (sec and see) and fibronectin-binding protein B (fnbB).

VIRULENCE FACTORSOFSTAPHYLOCOCCUS AUREUS WHICH PLAY AN IMPORTANT ROLEIN THE OCCURRENCE OF MASTITIS IN DAIRY CATTLE: A LITERATURE REVIEW

Staphylococcus aureus memiliki kepentingan di dunia kedokteran hewan sebagai agen penyebab mastitis pada sapi perah. Bakteri S. aureus dapat menghasilkan bermacam faktor virulensi yang dapat membantu patogen ini dalam setiap tahap proses patogenesis mastitis, dimulai dari perlekatan S. aureus ke sel ambing hingga menimbulkan kerusakan yang menyebar ke jaringan ambing. Penelitian ini merupakan penelitian studi literatur yang dilakukan dengan mengumpulkan dan menelaah berbagai artikel ilmiah yang terkait dengan topik penelitian ini melalui mesin pencari Google Scholar (https://scholar.google.co.id). Penelitian ini bertujuan untuk mengulas karakteristik beberapa faktor virulensi S. aureus yang sering dilaporkan berperan dalam kejadian mastitis pada sapi perah. Faktor virulensi tersebut antara lain yaitu biofilm, clumping factor, fibronectin binding protein, hemolisin, koagulase, Panton-Valentine leukocidin, kapsul, dan superantigen seperti toksin toxic shock syndrome (TSST), serta enterotoksin (SE). Kombinasi produksi faktor virulensi oleh S. aureus dianggap dapat meningkatkan derajat keparahan mastitis.

Exploring the Pathogenic Potential of Vibrio vulnificus Isolated from Seafood Harvested along the Mangaluru Coast, India

It has been observed that not all strains of Vibrio vulnificus are virulent. Determining the virulence of strains that are frequently present in seafood is of significance for ensuring seafood safety. This study is an attempt to predict the virulence of seafood-borne V. vulnificus isolated along the Mangaluru Coast, India. The isolates tested possessed a vcgC gene sequence with high similarity to that in the clinical strain. Transcriptional analysis of core virulence genes in seafood isolate E4010 showed the phenomenon of contact-mediated expression of rtxA1 which correlated well with the actin disintegration and cytotoxicity. These results suggest that the seafood isolates tested in this study possess a functional RtxA1 which could help in initiating the infection. However, other putative virulence genes such as vvpE encoding an extracellular protease, vvhA encoding hemolysin, flp encoding tad pilin and ompU encoding fibronectin-binding protein were also constitutively expressed. Virulence-associated attributes such as cytotoxicity and adherence matched the response of the clinical strain (p > 0.05). On the other hand, the environmental strains showed higher serum sensitivity compared with the clinical strain. These findings show that the part of virulence attributes required for the disease process might be intact in these isolates.