Distribution of Genes Encoding Toxin, Adhesion, and Antibacterial Resistance Among Various SCCmec?Types of Methicillin-Resistant?Staphylococcus aureusIsolated From Intensive Care Unit, Tehran, Iran

摘要

Background: Background: Most methicillin-resistant Staphylococcus aureus (MRSA) infections occur in health care settings; therefore, it is important to know about antimicrobial susceptibility, and carriage of virulence genes in S. aureus isolates. Objectives: The current study aimed at determining the prevalence of genes coding antimicrobial resistance, toxins, and adhesion factors among various SCCmec types of MRSA isolated from intensive care units (ICUs). Methods: From April 2016 to March 2017, a total of 200 MRSA species were isolated from various clinical samples of patients hospitalized in ICUs. The Kirby-Bauer disk diffusion method was employed to determine resistance pattern. Conventional polymerase chain reaction (PCR) assay was utilized to demonstrate antimicrobial resistance, toxins, and adhesion genes. Different SCCmec types of MRSA strains were determine by the multiplex PCR assay. Results: Antibiotic susceptibility testing revealed that all the isolates were sensitive to linezolid, teicoplanin, and vancomycin. The frequency of high-level mupirocin-resistant MRSA was 5.5%. The presence of resistance genes ant(4’)-Ia, aac(6’)-Ie/aph(2’’), tetM, msrA, ph(3’)-IIIa, ermA, msrB, ermB, ermC, and mupA were detected 73.5%, 60.5%, 57.5%, 37%, 36.5%, 34.5%, 24%, 17%, 15% and 5.5%, respectively. The most prevalent adhesion genes were clfA (93.5%) followed by clfB (90%), fnbA (81.5%), fnbB (77%), can (51%), ebp (46.5%), and bbp (2.5%). The frequency of etb, eta, pvl, and tst genes were 4.5%, 9.5%, 21.5%, and 61.5%, respectively. Inducible macrolide-lincosamide-streptogramin B (inducible MLSB resistance; iMLSB), and constitutive MLSB (cMLSB) phenotypes were observed in 88 (44%) and 26 (13%) isolates. Different SCCmec types comprising type III (56.5%), type IV (25%), type II (11%) and type I (7.5%) were identified among the MRSA strains. Conclusions: Results of the current study showed a high prevalence of resistance to commonly used antibiotics that can be a serious threat to patients hospitalized in ICUs. Also, the current study findings showed that different SCCmec types causing nosocomial infections were associated with specific antimicrobial resistance, adhesion, and toxin gene profilesBrucellosis is one of the main causes of economic loss in domestic animals due to abortions and infertility. Brucella is a facultative intracellular pathogen that survives in other cell types in addition to phagocytes. T cell mediated responses are necessary to eradicate the infection due to Brucella. Objectives: In this study the potential of recombinant protein rTF/Bp26/Omp31 as a novel Brucella subunit vaccine, protective efficacy, and immune response was evaluated in BALB/c mice. Methods: After in silico design of rTF/Bp26/Omp31 structure, the gene was cloned and expressed in Escherichia coli BL21 (DE3). Finally, purified protein by Ni-NTA was used as immunogenic to immunized mice. Results: Mice immunized with rTF/Bp26/Omp31 showed a vigorous humoral and cellular mediated immunity; results were compatible with IgG1 and IgG2a levels as well as high amounts of IFN-γ, IL-12, IL-4 and IL-10 production in immunized mice, compared with control groups (P < 0.05). Compared to control groups, mice vaccinated with rTF/Bp26/Omp31 showed a significant response and protection against subsequent Brucella infection (P < 0.05). Conclusions: Statistical analyses indicate similar responses in immunized mice exposed to rTF/Bp26/Omp31, compared with B. abortus RB51 and B. melitensis Rev.1 vaccines. These results showed the potential of rTF/Bp26/Omp31 as a candidate for the development of a subunit vaccine against brucellosis