The prevalence of adhesion and biofilm genes in Staphylococcus aureus isolates from bovine mastitis: A comprehensive meta-analysis.

BACKGROUND: Mastitis poses significant challenges to the dairy industry, resulting in economic losses and increased veterinary expenses. Staphylococcus aureus is a common cause of bovine mastitis, relying on efficient adhesion and biofilm formation for infection. OBJECTIVES: This study aimed to employ meta-analysis to investigate the occurrence of adhesion and biofilm genes in S. aureus associated with bovine mastitis, as documented in previous studies. METHODS: This meta-analysis was done according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses, examined 22 eligible articles and revealed varying prevalence rates of adhesion and biofilm genes in S. aureus isolates from bovine mastitis. RESULTS: Among the genes, clfB showed the highest prevalence (p-estimate = 0.905), followed by fnbA (p-estimate = 0.689) and fnbB (p-estimate = 0.502). The icaA and icaD genes also showed a relatively high prevalence (p-estimate = 0.694 and 0.814, respectively). Conversely, the biofilm-associated proteins gene had the lowest prevalence (p-estimate = 0.043). Subgroup analyses based on mastitis types and publication years revealed no significant differences in gene prevalence. Insufficient data hindered the analysis of fib, sasG , eno and bbp genes. CONCLUSION: This study provides valuable insights for managing S. aureus-induced bovine mastitis. Additionally, larger-scale research, particularly on less-studied genes, is necessary to comprehend the molecular roles of adhesion and biofilm genes in S. aureus-induced bovine mastitis.

A systematic review and meta-analysis revealed a high-level antibiotic resistance of bovine mastitis Staphylococcus aureus in Iran.

Staphylococcus aureus (S. aureus) is a frequent and major etiological agent of bacterial bovine mastitis, leading to high economic losses. This pathogen readily becomes resistant to many antibiotics, resulting in persistent noncurable intramammary infection (IMI) in animals and the development of multidrug-resistant (MDR) strains. The objectives of this study were to evaluate the prevalence of antimicrobial resistance (AMR) of S. aureus strains causing bovine mastitis in Iran according to published data from 2000 to 2021. As there is still a dearth of information on the AMR of S. aureus from Iranian bovine mastitis, the primary focus and subgroup analysis of the present study was performed on Iranian isolates. A systematic review was done according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Based on the initial search, 1006 article were identified. According to inclusion and exclusion criteria and removing duplications, 55 English articles and 13 Persian articles (a total of 68 articles) were finally analyzed. The highest overall prevalence of resistance was reported against penicillin G (p-estimate = 0.568 for all isolates, and p-estimate = 0.838 for Iranian isolates), followed by ampicillin (p-estimate = 0.554, and p-estimate = 0.670 for all isolates and Iranian isolates, respectively) and amoxicillin (p-estimate = 0.391, and p-estimate = 0.695 for all isolates and Iranian isolates, respectively). Besides, the lowest prevalence of resistant isolates was related to trimethoprim-sulfamethoxazole (p-estimate = 0.108 and 0.118 for all isolates and Iranian isolates, respectively) and gentamycin (p-estimate = 0.163 and 0.190, for all isolates and Iranian isolates, respectively). Our analysis showed that the Iranian isolates were more resistant to all antibiotics than those of all isolates. This difference was significant in the case of penicillin G, ampicillin, and erythromycin at 5%. To the best of our knowledge, except for ampicillin, AMR has increased over time for all the studied antibiotics in Iranian isolates. This increased rate was significant for penicillin G, amoxicillin, and tetracycline (p < 0.1). No differences in AMR were detected regarding the mastitis types (clinical vs. subclinical mastitis) for almost evaluated antibiotics. In conclusion, the prevalence of AMR S. aureus isolated from IMI was high particularly for bovine mastitis used antibiotics like penicillin G and ampicillin. Additionally, according to the increasing rate of AMR S. aureus in recent years in Iran, control strategies should be reinforced to avoid the spread of this pathogen and drug resistance.

Antibacterial and anti-biofilm properties of carvacrol alone and in combination with cefixime against Escherichia coli.

BACKGROUND: Plant-derived compounds can be used as antimicrobial agents in medicines and as food preservatives. These compounds can be applied along with other antimicrobial agents to strengthen the effect and/or reduce the required treatment dose. RESULTS: In the present study, the antibacterial, anti-biofilm and quorum sensing inhibitory activity of carvacrol alone and in combination with the antibiotic cefixime against Escherichia coli was investigated. The MIC and MBC values for carvacrol were 250 µg/mL. In the checkerboard test, carvacrol showed a synergistic interaction with cefixime against E. coli (FIC index = 0.5). Carvacrol and cefixime significantly inhibited biofilm formation at MIC/2 (125 and 62.5 µg/mL), MIC/4 (62.5 and 31.25 µg/mL) and MIC/8 (31.25 and 15.625 µg/mL) for carvacrol and cefixime, respectively. The antibacterial and anti-biofilm potential effect of carvacrol confirmed by the scanning electron microscopy. Real-time quantitative reverse transcription PCR revealed significant down-regulation of the luxS and pfs genes following treatment with a MIC/2 (125 µg/mL) concentration of carvacrol alone and of only pfs gene following treatment with MIC/2 of carvacrol in combination with MIC/2 of cefixime (p < 0.05). CONCLUSIONS: Because of the significant antibacterial and anti-biofilm activity of carvacrol, the present study examines this agent as an antibacterial drug of natural origin. The results indicate that in this study the best antibacterial and anti-biofilm properties are for the combined use of cefixime and carvacrol.

Cuminum cyminum L. Essential Oil: A Promising Antibacterial and Antivirulence Agent Against Multidrug-Resistant Staphylococcus aureus.

Cuminum cyminum L. (cumin) is valued for its aromatic and medicinal properties. There are several reports of antibacterial activity of C. cyminum essential oil (CcEO). Accordingly, the present study was conducted to investigate the mechanism(s) of action of the CcEO against multidrug-resistant (MDR) Staphylococcus aureus. Therefore, 10 S. aureus MDR isolates, obtained from different sources, were selected based on the antibiotic susceptibility patterns and the Clinical and Laboratory Standards Institute definition and subjected to the examinations. Our results exhibited promising bacteriostatic and bactericidal properties of the CcEO. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration values ranged from 5 to 10 and 10 to 20 µL ⋅ mL-1, respectively. Scanning electron microscope was used to assess the bacterial cell structure and morphology after the induction with 1/2 MIC concentration of the CcEO. The observed morphological changes appeared to be deformation of the cell membrane and destruction of the cells. In the case of quorum sensing inhibitory potential, treatment of S. aureus isolates with the sub-MIC concentrations (1/2 MIC) of the CcEO significantly reduced the hld expression (3.13-fold downregulation), which considerably controls S. aureus quorum-sensing accessory regulator system. Another virulence factor influenced by the CcEO was the polysaccharide intercellular adhesion production system, as an important component of cell-cell adhesion and biofilm formation. Consequently, the expression level of the intercellular adhesion (ica) locus in the S. aureus cells was examined following treatment with CcEO. The results showed significant decrease (-3.3-fold) in ica expression, indicating that the CcEO could potentially interfere with the process of biofilm formation. Using the ethidium bromide efflux inhibition assay, the S. aureus NorA efflux pump was phenotypically but not genotypically (in quantitative polymerase chain reaction assay) affected by the CcEO treatment. Using gas chromatography-mass spectrometry analysis, cuminic aldehyde (38.26%), α,ß-dihydroxyethylbenzene (29.16%), 2-caren-10-al (11.20%), and γ-terpinene (6.49%) were the most detected compounds. The antibacterial and antivirulence action of the CcEO at sub-MIC concentrations means that no microbial resistance will be promoted and developed after the treatment with this agent. These findings revealed that the CcEO is a promising antibacterial agent to control infections caused by the MDR S. aureus strains.

Streptococcus pneumoniae quorum sensing and biofilm formation are affected by Thymus daenensis, Satureja hortensis, and Origanum vulgare essential oils.

The aim of this study was to investigate the effect of Thymus daenensis L., Satureja hortensis L., and Origanum vulgare L. essential oils (EOs) on the planktonic growth, biofilm formation, quorum sensing (QS), and competence system (CS) of Streptococcus pneumoniae. The anti-biofilm activity of EOs was determined by Microtiter-Plate Test (MtP) and scanning electron microscope (SEM). The QS and CS inhibitory activities were determined on the pre-grown biofilm by gene expression analysis using quantitative real-time RT-PCR. Using gas chromatography-mass spectrometry analysis, the major components of the tested EOs were detected. The MtP and SEM detected a significant inhibitory effect of the three EOs on biofilm formation at sub-minimum inhibitory concentrations (MICs). The most anti-biofilm activity was seen for T. daenensis. LuxS and pfs genes (genes involved in QS) downregulated the following treatment with MIC/2 of Thymus and Satureja EOs. Thymol, carvacrol, p-cymene, pulegone, and 1,8-cineole were the major components of the tested EOs. The used EOs seem to be good candidates for preventing biofilm formation and subsequent colonization of S. pneumoniae. This study introduced T. daenensis and S. hortensis as new anti-biofilm and QS inhibitor agents with a natural origin.