Background Nosocomial infections and persistence of multidrug resistant biofilm forming Acinetobacter baumannii in hospitals has made it as a serious problem in healthcare settings worldwide. Methods A total of 100 A. baumannii clinical isolates from immunocompromised patients hospitalized in ICU were investigated for biofilm formation, the presence of biofilm related genes ( bap, ompA, csuE, fimH, epsA, bla PER-1 , bfmS, ptk, pgaB, csgA, kpsMII ), integron characterization and molecular typing based on REP-PCR. Results All isolates were resistant to three or more categories of antibiotics and considered as multidrug resistant (MDR). A total of 32 isolates were resistant to all tested antibiotics and 91% were extensively drug-resistance (XDR). All isolates were able to produce biofilm and 58% of isolates showed strong ability to biofilm formation. All strong biofilm forming A. baumannii isolates were XDR. All A. baumannii isolates carried at least one biofilm related gene. The most prevalent gene was csuE (100%), followed by pgaB (98%), epsA and ptk (95%), bfmS (92%) and ompA (81%). 98% of isolates carried more than 4 biofilm related genes, simultaneously. Class I integron (67%) was more frequent in comparison with class II (10%) ( P < 0.05). The REP-PCR patterns were classified as 8 types (A-H) and 21 subtypes. The A1 (23%) and C1 (15%) clusters were the most prevalent among A. baumannii isolates ( P < 0.05). According to the REP-PCR patterns, 23% of all isolates had a clonal relatedness. Conclusion Our study revealed the high frequency of biofilm forming XDR A. baumannii in ICU patients, with a high prevalence of biofilm related genes of csuE and pgaB. It seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of XDR A. baumannii in our country.

Background:Brucellosis is an infectious disease that is caused by Brucella spp. As Brucella spp. are intramacrophage pathogens, the treatment of this infection is very difficult. On the other hand, due to the side effects of the brucellosis treatment regime, it is necessary to find new antimicrobial agents against it.Objectives:The aim of this study was to investigate the antimicrobial effect of silver nanoparticles against Brucella abortus 544 in the intramacrophage condition.Materials and Methods:The antimicrobial effect of silver nanoparticles was determined by an agar well diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles against B. abortus 544 were determined by a broth macrodilution method. The effect of time on the antimicrobial activity of silver nanoparticles was analyzed. The effect of silver nanoparticles on the intramacrophage survival of B. abortus 544 was studied on mice peritoneal macrophages.Results:The well diffusion agar study showed that silver nanoparticles have an antimicrobial effect on B. abortus 544. The MIC and MBC of silver nanoparticles against B. abortus 544 were; 6 ppm and 8 ppm, respectively. The silver nanoparticles showed antibacterial effects within 40 minutes. The results of the macrophage culture indicated that silver nanoparticles have antibacterial activity against intramacrophage B. abortus 544, and the highest efficiency was observed at a concentration of 8-10 ppm of silver nanoparticles.Conclusions:The results showed that silver nanoparticles have an antimicrobial effect against intramacrophage B. abortus 544.

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Background:Treatment of Pseudomonas aeruginosa PAO-1 infections through immunological means has been proved to be efficient and protective.Objectives:The purpose of this study was to produce a conjugate vaccine composed of detoxified lipopolysaccharide (D-LPS) P. aeruginosa and diphtheria toxoid (DT).Materials and Methods:Firstly, LPS was purified and characterized from P. aeruginosa PAO1 and then detoxified. D-LPS was covalently coupled to DT as a carrier protein via amidation method with adipic acid dihydrazide (ADH) as a spacer molecule and 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDAC) as a linker. The molar ratio of LPS to DT in the prepared conjugate was 3:1. The immunogenicity of D-LPS-DT conjugate vaccine in mice model was evaluated as well.Results:The conjugate was devoid of endotoxin activity and 0.125 U/mL of D-LPS was acceptable for immunization. D-LPS-DT conjugate was nonpyrogenic for rabbits and nontoxic for mice. Mice immunization with D-LPS-DT conjugate vaccine elicited the fourfold higher IgG antibody compared to D-LPS. Anti-LPS IgG antibody was predominantly IgG1 subclass and then IgG3, IgG2a and IgG2b, respectively.Conclusions:Vaccine based on the conjugation of P. aeruginosa PAO-1 LPS with DT increased anti-LPS antibodies and had a significant potential to protect against Pseudomonas infections.

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Background:Wound infection is a common problem in hospitals and is typically caused by the antibiotic-resistant Staphylococcus aureus, which is a major pathogen for skin and soft tissue infections worldwide.Objectives:The aim of this study was to investigate the synergistic antibacterial effect of plant peptide MBP-1 and silver nanoparticles on infected wounds caused by S. aureus.Materials and Methods:The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of MBP-1 and silver nanoparticles both on their own and in combination form were determined against S. aureus via macrodilution and microdilution methods. The synergistic antibacterial effect of silver nanoparticles and MBP-1 was investigated on infected wounds caused by S. aureus in a mouse model.Results:The MIC and MBC of MBP-1 were found to be 0.6 and 0.7 mg/mL, respectively. MIC and MBC of silver nanoparticles were determined to be 6.25 and 12.5 mg/L, respectively. MIC and MBC of the silver nanoparticles and MBP-1 combination were found to be 3.125 mg/mL, 0.5 mg/L; and 6.25 mg/mL, 0.6 mg/L, respectively. The infected wound healed properly after the combined use of MBP-1 and silver nanoparticles.Conclusions:The synergistic effect was found on the healing of infected wounds caused by S. aureus by using an MBP-1 and silver nanoparticles combination in a mouse model.