Background. In this study antimicrobial effect of ethanolic and aqueous extracts of Juglans regia bark in Iran was evaluated on four different oral bacteria, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis, and Staphylococcus aureus. Methods. Aqueous and ethanol extracts of Juglans regia bark were prepared by using disk diffusion technique and Minimal Inhibitory Concentration (MIC) methods. Tetracycline 30 μg and Erythromycin 15 μg were used as positive control and water as negative control in disk diffusion and MIC methods. Data were analyzed by ANOVA test. Results. The results showed that S. sanguis and S. mutans were the most sensitive and the most resistant bacteria against ethanolic and aqueous extracts, respectively. Ethanolic extract had significant antibacterial effect against all tested bacteria. Aqueous extract did not show antibacterial effect on S. mutans, in contrast to ethanolic extract. Aqueous extract had significantly antibacterial effect against Staphylococcus aureus, S. salivarius, and S. sanguis compared to control (P < 0.0001), but it did not show effect on S. mutans when compared with Erythromycin. According to the obtained MIC values, ethanol extract of Juglans regia bark had the lowest rate. Conclusion. The results may provide the basis for using natural antimicrobial substance for oral hygiene prophylaxis purposes.

Emerging antimicrobial resistance in burn wound bacterial pathogens is a serious therapeutic challenge for clinicians. In the present study, most of the isolates were MDR. This finding indicated an alarming spread of resistant isolates and suggested that infection control strategies should be considered. Resistance to carbapenems is influenced by several factors, not all of which were evaluated in our study; however, the results showed that production of MBLs and overexpression of the mexB gene were the most frequent mechanisms in carbapenem-resistant isolates.

Background As an opportunistic pathogen, Escherichia coli ( E. coli ) is widely recognized as the main cause of nosocomial infections as well as some disorders especially those associated with urinary tract infections (UTIs). This study, therefore, sets out to determine the extent of antibiotic resistance to quinolones and to measure the frequency of qnr genes (A, B, and S) within extended-spectrum beta-lactamase (ESBL) and non-ESBL-producing strains of E. coli isolated from UTI-diagnosed patients as well as to investigate their antimicrobial susceptibility patterns for some selected antibiotics in southwest Iran. Methods Two hundred E. coli strains were isolated from UTI-diagnosed patients, hospitalized in nine different wards of Ahvaz Golestan Hospital between November 2015 and March 2016. The isolates were confirmed through well-practiced phenotypical methods. Moreover, the antimicrobial susceptibility test was successfully performed using a disk diffusion method. ESBL production among the isolates was screened by double disk synergism test (DDST), and the qnr genes were identified using a multiplex PCR. Results Out of the 200 samples collected, 167 isolates were confirmed to be E. coli strains. Maximum and minimum resistance were reported against nalidixic acid and chloramphenicol with 65.3% and 17.4%, respectively. Most of the isolates were resistant to all three types of quinolones studied in this research. Using multiplex PCR, the qnr genes were found in 100 (59.88%) strains ( qnr A = 10, qnr B = 21, qnr S = 41, qnr B-S = 21, qnr B-A = 1, qnr A-S = 3, qnr A-B-S = 3), 58% of which was found among ESBL-producing isolates. Conclusions Resistance to quinolones antibiotics was highest among ESBL-producing isolates harboring, especially qnr S among other determinants of the qnr gene. There is a need for sensitive antibiotic stewardship especially in hospitals of Ahvaz, Khuzestan province. Further research is needed to ascertain the gravity of quinolones resistance in Iran and to quickly act against its spread among other nosocomial pathogens.

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Background: Streptococcus mutans, an organism colonizing the oral cavity, is considered to be the main cause of dental caries. In addition to dental caries and related pyogenic dental infections, S. mutans is also a very important endocarditis agent. The participation of this microorganism in both oral and non-oral diseases has prompted interest in the knowledge of this susceptibility to antimicrobial agents. The aim of this study was to determine the antimicrobial susceptibility of S. mutans biotypes isolated from children dental caries free. Methods: Unstimulated saliva samples were collected from 60 children, diluted and cultured onto mitis salivarius bacitracin (MSB) agar plates for the selective isolation and enumeration of S. mutans. The MSB agar plates were incubated anaerobically (H 2 :CO 2 : N 2 10:10:80) for two days a 37 • C. The biotyping of S. mutans was realized using the api Zym system (bioMérieus; Marcy-lÉtoile, France). The minimal inhibitory concentrations were evaluated against penicillin, amoxycillin, cefazolin, erythromycin, clindamycin, imipenem and vancomycin by using an agar dilution method with concentrations between 0.003 and 32 ug/ml. Results: Twenty biotypes were detected in the 74 strains of S. mutans isolated. The most frequent byotipes were the 2,3,10 and 13 (n = 6). Nineteen out of the 23 children in whom 2 strains of S. mutans were isolated, and 7 children in whom 3 strains of S. mutans were isolated presented different biotypes of S. mutans. All biotypes were highly sensitive to penicillin, amoxicillin, cefazolin, erythromycin, clindamycin, imipenem and vancomycin; 50 and 90% of S. mutans strains were inhibited by using concentrations of less than 0.12 and 0.5 ug/ml, respectively, for all antibiotics studied. Conclusion: S. mutans biotypes were highly sensitive to he antibiotics tested.