Mixed oral biofilms are controlled by the interspecies interactions of Fusobacterium nucleatum.

BACKGROUND: Fusobacterium nucleatum (F. nucleatum) is an integral component of supra- and subgingival biofilms, especially more prevalent in subgingival areas during both periodontal health and disease. AIMS: In this review, we explore the physical, metabolic, and genetic interactions that influence the role of F. nucleatum in the formation of mixed oral biofilms. The role of F. nucleatum in antibiotic resistance in oral biofilms was discussed and some therapeutic strategies were proposed. METHODS: PubMed, Scopus, Google Scholar, and the Web of Science were extensively searched for English-language reports. RESULTS: F. nucleatum-derived proteins such as RadD, Fap2, FomA, and CmpA are involved in direct interactions contributing to biofilm formation, while autoinducer-2 and putrescine are involved in metabolic interactions. Both groups are essential for the formation and persistence of oral biofilms. This study highlights the clinical relevance of targeted interactions of F. nucleatum in supra- and subgingival oral biofilms. CONCLUSIONS: By focusing on these interactions, researchers and clinicians can develop more effective strategies to prevent biofilm-related disease and reduce the spread of antibiotic resistance. Further research in this area is warranted to explore the potential therapeutic interventions that can be derived from understanding the interactions of F. nucleatum in oral biofilm dynamics.

Detection of qacΔE Efflux Pump Gene among the Clinical Isolates of Escherichia coli and its Correlation with Resistance to Disinfectants.

BACKGROUND: Disinfectants and antiseptics inhibit the dissemination of pathogenic organisms in hospitals but often cause disinfectant-resistant microorganisms, an important factor for nosocomial infection. This study aimed to evaluate the correlation between qacΔE efflux pump gene and its resistance to disinfectants among Escherichia coli clinical isolates. METHODS: A total of 97 E. coli isolates were isolated from patients with urinary tract infections. The minimum inhibition concentration (MIC) value of chlorhexidine and benzalkonium chloride was determined using broth microdilution method. Effect of efflux pumps was assessed by MIC test in the presence of phenylalanine-arginine ß-naphthylamide (PAßN), and then the qacΔE efflux pump gene was detected using polymerase chain reaction (PCR). RESULT: Of the isolates, 85.6% and 61.9% were resistant to chlorhexidine and benzalkonium chloride, respectively. Following the treatment of isolates with the efflux pump's inhibitor, PAßN, the MIC value of chlorhexidine and benzalkonium chloride decreased in 75.2% and 57.7% of the isolates, respectively. A significant correlation was found between PAßN treatment and the change in the resistant strains to susceptible strains (p = 0.021). The qacΔE gene was detected in 84.5% (n = 82) of the isolates, and the presence of the gene amongst disinfectant-resistant strains was also significant (p < 0.001). CONCLUSIONS: It is suggested to conduct other studies on other efflux pumps, as well as to periodically monitor the resistance to disinfectants. Substances inhibiting efflux pumps and neutral compounds are effective in the reduction of resistance to disinfectants. New disinfectants and drugs should be designed.

Antibacterial and Anti-Biofilm Activities of Silver Nano Particles Conjugated to Chitosan Against Multi-Drug Resistant Bacteria.

BACKGROUND: Nowadays, most of the traditional and conventional antibiotics are not effective against drug resistant bacterial strains. The emergence and spread of drug resistant bacterial cells calls for new therapeutic agents and strategies to control and treat the infections caused by these bacteria. In this regard, the application of nano-technology in medicine is an interesting approach. Therefore, the aim of this study was to evaluate the antibacterial and anti-biofilm activities of Ag Np conjugated to chitosan against multidrug resistant isolates of Staphylococcus aureus and Acinetobacter baumannii. METHODS: Synthesis of the Ag Np and chitosan Np were performed according to the Turkevich and Ionic gelation methods, respectively. Then conjugation of nanoparticles was carried out by standard method. FTR analysis and transmission electron microscopy were used for validation of nanoparticle conjugation. Twenty clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and 20 clinical isolates of carbapenem resistant Acinetobacter baumannii (CRAB) were obtained from the microbial bank of Imam Khomeini hospital of Tehran, Iran. MIC values of the nanoparticles alone and in conjugation were determined using the microbroth dilution method. Then, fractional inhibitory concentration of agents was concluded by standard method. Finally, anti-biofilm activities of the conjugated Ag Np-chitosan at sub-MIC concentrations was tested against bacterial isolates. RESULTS: Synthesis of Ag Np resulted in the formation of nanoparticles with 10 nm dimensions. MIC90 of the chitosan, Ag Np and their conjugated form were respectively 64, 16, and 8 µg/mL against CRAB isolates. Also, MIC90 of the tested agents, in the same order as mentioned above, were 32, 16, and 4 µg/mL against MRSA. Combination of the agents had additive (0.625) and synergistic (0.375) effects against CRAB and MRSA. Ability of biofilm formation was dramatically reduced by » MIC concentration (2 µg/mL) against the CRAB and ½ MIC concentration (2 µg/mL) in the case of the MRSA isolates. CONCLUSIONS: Ag Np-chitosan conjugation, an ideal alternative for ineffective antibiotics, exhibits great antibacterial and anti-biofilm effects against CRAB and MRSA isolates.