Background: Morbidity and mortality due to multidrug-resistant (MDR) bacteria are of great concern in burn patients. In this critical condition, synergism between antimicrobial peptides and conventional antibiotics would be a promising strategy. Accordingly, this study aimed to determine the therapeutic value of melittin as a natural peptide by examining its synergistic effect with conventional antibiotics against MDR isolates of Acinetobacter baumannii and Pseudomonas aeruginosa . Materials and Methods: Fifteen clinical isolates for each kind of bacteria were collected from burn patients. Antibiotic susceptibility of all isolates was evaluated by disk diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration for melittin, colistin, doripenem, doxycycline, and ceftazidime were also examined. Fractional inhibitory concentration (FIC) of melittin in combination with the antibiotics was determined for six MDR isolates. The cytotoxicity of melittin in combination with the antibiotics was examined on a normal human cell line. Results: The geometric means of MIC (GM _MIC ) for melittin and doripenem after combination were reduced to 61.5- and 51.5-fold, respectively, against MDR A. baumannii isolates. These reductions for melittin–doripenem and melittin–ceftazidime against MDR P. aeruginosa isolates were (63.5 and 58)-fold and (16 and 11)-fold, respectively. FIC for melittin–doripenem against A. baumannii and FIC for melittin–doripenem and melittin–ceftazidime against P. aeruginosa strains were ≤0.5. This issue caused a decrease of up to 104-, 68-, and 17-fold, respectively, in the cytotoxicity of melittin. Conclusion: In conclusion, the synergism of melittin at its nontoxic dose with doripenem and ceftazidime could be of great therapeutic value as a topical drug against burn infections caused by MDR bacteria.

Background: Acinetobacter baumannii has emerged as a highly troublesome pathogen and a leading cause of mortality and morbidity among hospitalized burn patients. Objectives: The aims of this study were to determine the frequency of the AdeABC genes and the role of the efflux pump (s) in the imipenem resistance of A. baumannii strains isolated from burn patients. Materials and Methods: This study was conducted on 60 A. baumannii isolates collected from 240 wound samples of burn patients admitted to the Burn Unit of Shahid Motahari Burn hospital, Tehran, Iran. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion and broth microdilution according to the clinical and laboratory standards institute (CLSI) guidelines. The activity of the efflux pump was evaluated using the efflux pump inhibitor, the phenylalanine-arginine Β-naphthylamide (PAΒN). The AdeABC genes were detected by polymerase chain reaction (PCR) and sequencing. Results: In this study, 100% of the isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole, and piperacillin/tazobactam; 56 (94%) to gentamicin; 50 (81%) to amikacin; 58 (97%) to imipenem; and 45 (76%) to tetracycline. Additionally,all the isolates were susceptible to colistin. The susceptibility of the strains to imipenem was highly increased in the presence of the efflux pump inhibitor such that for 58 (96.6%) of the isolates, the PAΒN reduced the minimum inhibitory concentrations (MIC) by 4- to 64-fold. The adeA and adeB genes were detected in 60 (100%) of the isolates, and the adeC gene was present in 51 (85%). Conclusions: The efflux pump may play a role in antibiotic resistance in A. baumannii isolates. The ability of A. baumannii isolates to acquire drug resistance by the efflux pump mechanism is a concern. Thus, new strategies are required in order to eliminate the efflux transport activity from resistant A. baumannii isolates causing nosocomial infections. Keywords: Antibiotic Resistance; Burn; Efflux Pump Inhibitor; AdeABC; Acinetobacter baumannii

Background and Objectives: Colorectal cancer is one of the most types of cancer. Researchers have shown that lactic acid bacteria have antitumor activity. The cell wall of Lactococcus lactis, as the bacterial cytoplasmic extract and nisin can affect the proliferation of cancer cells. Since cyclin D1 plays an important role in the progression of the cell cycle, its regulation can also be a therapeutic approach. We investigated the antiproliferative effect of cell wall, cytoplasmic extract and nisin on SW480 cancer cell line and the expression level of cyclin D1 gene in treated cancer cells. Materials and Methods: SW480 cell lines were treated with different concentrations of bacterial cell wall, cytoplasmic extract and nisin. MTT test was also performed. The expression level of cyclin D1 gene was determined using Real time PCR. Data were analyzed using Graph Pad Prism software. Results: The growth rate of cancer cells treated with nisin has significantly decreased compared to the cancer cells treated by other two substances (p< 0.05). Survival rates of the cancer cells treated by nisin at a concentration of 2000 μg, cytoplasmic extract, and cell wall were 34%, 47% and 49%, respectively. Real-time PCR results showed that cyclin D1 mRNA expression has significantly decreased in nisin treated sw480 cells (P<0.05). Conclusion: The results of this study show that nisin, bacterial cytoplasmic extract, and bacterial cell wall have antiproliferative effects, which are associated with the decreased expression of cyclin D1 in SW480 cell line.

Frequency of bla TEM , bla SHV , bla CTX-M, and qnrA Among Escherichia coli Isolated From Urinary Tract Infection - Archives of Clinical Infectious Diseases - - Kowsar