Avicenna Journal of Clinical Microbiology and Infection
Year:2018 | Volume:5 | Issue:1|Papers Count:7

Background: Azadirachta indica A. Juss (Neem) has been used against a few diseases in traditional medicine. This study was conducted to evaluate the antibacterial activity of Neem leaves extract against some antibiotic sensitive and resistant strains of important human pathogenic bacteria.Methods: The antimicrobial activities of ethanol, methanol, and ethyl acetate extracts of Azadirachta indica A. juss leaves were evaluated against some pathogenic bacterial strains including S. aureus ATCC 6538, E. faecalis ATCC 1394, P. aeroginosa ATCC 9027, E.coli, ATCC 25922, and their clinical isolates using agar well diffusion and MTT microdilution methods. MBC was determined by subculturing from microdilution assays.Results: The results revealed that methanol extract has the strongest growth inhibitory effect on both standard and clinical isolated strains of P. aeroginosa. Ethyl acetate and ethanol extracts, showing a growth inhibitory effecton both standard and hospital isolated strains ofS. aureus. In the case of E. faecalis, ethanol and methanol extracts showed the highest growth inhibitory effect against standard and clinical strains, respectively. According to the MIC index results, the methanol extract has a bactericidal activity against both standard and nosocomial strains ofS. aureus and P. aeroginosa and bacteriostatic activity against nosocomial strain of E. faecalis.Ethanol extract showed bactericidal activity against both standard and nosocomial strains ofE. faecalis and P. aeroginosa and bacteriostatic activity against nosocomial strain of S. aureus. Ethyl acetate extract had shown bactericidal activity against standard strains ofS. aureus and P. aeroginosa and bacteriostatic against nosocomial strain of S. aureus and standard strain of E. faecalis.Conclusions: Results revealed that Neem may be a prospective therapeutic agent to combat antibiotic resistant bacteria.

Erythema induratum of bazin (EIB) is a hypersensitivity reaction to Mycobacterium tuberculosis infection. The diagnosis can be difficult because tubercle bacilli are usually not found in smears or cultures of lesions. This study reports on a case of EIB in a 13-year-old female, who presented multiple tender nodules on her lower extremities. Biopsy of the nodule revealed histopathologic changes compatible with erythema induratum. Quanti FERON test was positive. The patient received a 6-month duration of anti-tuberculosis treatment. The lesions disappeared during therapy, and nopigmentation was observed at the end of treatment. After a year of follow up, there was no recurrence of the disease.

Helicobacter pyloriis a close relative of Campylobacter species, with the ability to colonize the human gastrointestinal tract. This gastric pathogen is a flagellated, Gram-negative bacterium. Chronic gastritis, mucosa-associated lymphoid tissue (MALT) lymphoma, duodenal ulcer, and gastric ulcer are the outcomes of persistent infection with this pathogen. Recent studies have shown a direct relationship betweenH. pylori and development of gastric adenocarcinoma. A 7- to 14-day course of broad-spectrum antibiotics is required for the elimination ofH. pylori. Treatment failure due to chromosomally encoded antibiotic resistance is increasing rapidly, which underlines the importance of new regimens against this pathogen. The vast diversity of natural compounds in living microorganisms such as algae, as well as various dietary components in herbs and foods, provides a new opportunity for the establishment of therapeutic compounds. The majority of intra- and extracellular metabolites in algae have potent inhibitory effects onH. pylori, leading to the development of novel therapeutic agents for gastric ulcer. Application of bioinformatics-based tools has encouraged the scientific community to find novel targets and have led to the development ofin silico drugs against the pathogenic elements ofH. pylori. Further research on metabolite-based therapeutic agents with the aid of modern tools can be a milestone in the management of the emerging risk of gastric ulcer.

Background: Staphylococcus aureus is the major causative agent of hospital-acquired and community-acquired infections. These bacteria produce a wide variety of exotoxins, including Toxic Shock Syndrome Toxin (TSST) and virulence factors, which are thought to contribute to its pathogenic potential.Objectives: The aim of this study was to identify tsst gene in S. aureus isolated from patients and healthy carriers.Methods: In this cross-sectional study, a total of 60human S. aureus isolates were collected from individuals referred to Shahid Beheshti hospital (patients, n=40) and healthy farm workers (n=20) in Hamadan province of Iran. Thereafter, DNA samples were extracted using the phenol-chloroform method and the samples were investigated fortsst gene using a specific PCR assay.Results: The DNA fragment corresponding to the tsst gene (326 bp) was observed in 45% (9 out of 20) of S. aureus isolated from healthy farm workers; while, 22.5% (9 out of 40) of patients’ isolates were found to be positive for tsst gene, which indicated that in total 30% of the isolates possessed this gene.Conclusions: The results of the present study showed the high prevalence of the tsst gene among S. aureus isolated from healthy farm workers and patients. Therefore, appropriate precautions must be considered to decrease the risk of transmission of such isolates to other humans.

Background: Nowadays, a new technique such as photodynamic therapy (PDT) is used to achieve effective root canal disinfection and eliminateEnterococcus faecalis as the most prevalent species associated with secondary endodontic infections and treatment failures. Employment of an optimized nontoxic photosensitizer (PS) such as indocyanine green (ICG) is a crucial part of this technique; the current study aimed at improving ICG photodynamic properties through conjugation of ICG into nano-graphene oxide (nGO) as a new PS, to evaluate the antimicrobial effects of nGO/ICG againstE. faecalis.Methods: The nGO was synthesized based on the modified Hummer method and then, direct loading of ICG onto its surface. The nGO formation was evaluated using the scanning electron microscope (SEM). The antimicrobial effect of nGO/ICG-PDT againstE.faecaliswas assessed by counting colony forming units (CFUs).Results and Conclusion: The SEM analysis confirmed successful synthesis of nGO. The nGO/ICG-PDT at an incorporated concentration of 400 mg/mL ICG with irradiation at an energy density of 31.2 J/cm2 showed significant reduction in the number of E. faecalis higher than PDT based on ICG (1000 mg/mL) (P<0.05). Since nGO-ICG-PDT showed a significant reduction in the count of E. faecalis at low concentration of ICG (400 mg/mL), it could be proposed as a new approach to treat endodontic infections, alone or in combination with conventional root canal treatment.

Background: Antibiotic resistance among biofilm-producing pathogenic bacteria is a major health concern today. Plants, as a rich source of medicinal compounds, are interestingly explored for discovering new antibiotics.Objectives: In this study, the effect of Dracocephalum polychaetum Bornm extract on the growth, biofilm formation, and expression of biofilm-related genes in methicillin-resistant Staphylococcus aureus (MRSA) was explored.Methods: Antimicrobial activity of D. polychaetum aerial part extract in MRSA samples was evaluated by agar well diffusion method.Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract were determined according to the CLSI manual. Inhibition of biofilm formation was analyzed by microtitre plate method. Expression ofica A, icaD, bap, sar, andagr genes was studied by Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) technique.Results: The antimicrobial effect of the extract against 20 MRSA strains was appropriate. The MIC and MBC of the extract were in the range of 0.781 - 25 mg mL-1 and 1.56 - 50 mg mL-1, respectively. Biofilm formation was inhibited in all of the isolated MRSA strains in sub-MIC concentrations. PCR results demonstrated that half of the samples had both ica A and ica D genes, about 1.3 had icaA gene, and 1.6 had merelyica D gene. RT-qPCR data showed that the expression of sar, bap, ica D and ica A genes was significantly reduced by the extract.Conclusions: Collectively, the results demonstrated that D. polychaetum not only had anti-staphylococcus effects against MRSA but also suppressed biofilm formation both at phenotype and gene expression levels. Its effects are comparable to the effect of other Dracocephalum sp.Further in vivo studies can reveal the potential application of this plant against MRSA strains.

Background: Staphylococcus aureus is a significant pathogen and major cause of nosocomial and community-acquired infections.The current study aimed at investigating the frequency of Panton-Valentine leukocidin (PVL) gene as a serious virulence factor causing WBC destruction.Methods: Collectively, 100 species of S. aureus were isolated from Isfahan, Iran, hospitals and confirmed by biochemical tests (coagulase, mannitol fermentation, and DNase). The antibiotic resistance patterns were studied by the disk diffusion method.Results: Out of the 100 isolates, 56.2% were PVL positive of which 19.8% from abscess, 51.7% from wound, 23.2% from bedsore, and 5.3% from tracheal secretion. Among the detected isolates, 87.8% were resistant to methicillin.Conclusions: The current study showed the high frequency of PVL in wound strains. Further studies are required to understand the distribution of these virulent isolates in order to decrease the risk of infection. High quality hospital cares as well as new antibiotics is required to combat the multidrug resistant bacteria.