Standard Disk Diffusion Method Research Articles

VOLATILE COMPOSITION, ANTIOXIDANT PROPERTY AND ANTIMICROBIAL ACTIVITIES AGAINST FOOD-BORNE BACTERIA OF VIETNAMESE THYME (Thymus vulgaris L.) ESSENTIAL OIL

The essential oil (EO) obtained from the leaves of the thyme (Thymus vulgaris L.) grown in Vietnam was found to contain thymol (39.79%), cymene (17.33%), and γ-terpinene (13.45%) as the main volatile components. The antimicrobial activities of this oil were screened against several food-borne bacteria and fungi species. Significant growth inhibition effects against food-borne bacteria Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Salmonella Typhimurium were observed using the standard disc diffusion method. Thyme EO showed the antibacterial effect against all the test pathogenic strains with the inhibition zones were 23.3 ± 0.4 mm, 24.7 ± 0.4 mm, 29.0 ± 0.7 mm, 32 ± 0.7 mm in diameter against B. subtilis, E. coli, S. Typhimurium and S. aureus, respectively. The minimum inhibitory concentration (MIC) determined by micro-dilution method in MHB liquid medium was 1.56 µl/ml. The bactericidal concentrations (MBC) was 3.13 µl/ml for three isolates from B. subtilis, E. coli, and S. aureus, while the MBC tested for S. typhi was 1.56 µl/ml. The antifungal properties of the thyme EO were also determined in this study against three important pathogenic fungi such as Candida albicans, Rhizoctonia solani and Fusarium oxysporum with the inhibition zones ranging approximately from 23.20 ± 0.06 to 44.10 ± 0.03 mm. On the other hands, the results also showed the antioxidant activity of Vietnamese thyme EO and suggested that thyme EO can be applied in food industries as natural flavoring preservatives/additives to control food spoilage and food born bacteria and fungi.

Antibiotic Resistance of Enterobacteriaceae Isolated from Fresh Fruits and Vegetables and Characterization of their AmpC β-Lactamases

Enterobacteria may gain antibiotic resistance and be potent pathogens wherever they are present, including in fresh fruits and vegetables. This study tested the antibiotic resistance of enterobacteria isolated from 13 types of local and imported fresh fruits and vegetables (n = 105), using the standard Kirby-Bauer disk diffusion method. Phenotypic and genotypic characterizations of AmpC β-lactamases were determined in cefoxitin-resistant isolates. Ten percent of the enterobacteria tested (n = 88) were pansusceptible, 74% were resistant to at least one antibiotic, and 16% were multidrug resistant. Enterobacteria isolates showed the highest antibiotic resistance against ampicillin (66%), cephalothin (57%), amoxicillin-clavulanic acid (33%), cefoxitin (31%), tetracycline (9%), nalidixic acid (7%), trimethoprim (6%), and kanamycin (5%). Three isolates showed intermediate resistance to the clinically important antibiotic imipenem. Escherichia coli isolated from lettuce exhibited multidrug resistance against five antibiotics. Fifteen isolates were confirmed to have AmpC β-lactamase, using the inhibitor-based test and the antagonism test; the latter test confirmed that the enzyme was an inducible type. Four types of ampC β-lactamase genes (CIT, EBC, FOX, and MOX) were detected in eight isolates: four Enterobacter cloacae isolates and one isolate each of Citrobacter freundii, Enterobacter asburiae, Enterobacter hormaechei, and Enterobacter ludwigii. It was concluded that fresh fruits and vegetables might play a role as a source or vehicle for transferring antibiotic-resistant bacteria that might spread to other countries through exportation. The clinically significant AmpC β-lactamase was rarely documented in the literature on bacteria isolated from fruits and vegetables, and to our knowledge, this is the first report on the detection of an inducible type in such commodities.

Virulence genes and antibiotic resistance of Pseudomonas aeruginosa isolated from patients in the Northwestern of Morocco.

Pseudomonas aeruginosa is an ubiquitous bacterium causes various community-acquired and nosocomial infections. In this investigation, we aimed to screen the antibiotic susceptibility patterns and the prevalence of virulence factor genes in a set of Pseudomonas aeruginosa isolated from nosocomial and community-acquired infections in the Northwestern of Morocco. A total of 155 of Pseudomonas aeruginosa strains were collected (January 2015 - December 2016) from nosocomial and community-acquired infections at hospital centers and clinical laboratories in the Northwestern of Morocco. Antimicrobial susceptibility test was performed by the standard disk diffusion method. In addition, PCR assays were used for screening five virulence encoding genes (lasB, algD, plcH, exoA, and exoS). Our results revealed that high level of antimicrobial resistance was detected towards aztreonam (27.1%) followed by meropenem (14.2%). The resistance to imipenem was significantly higher in strains isolated from nosocomial infections (12.7%) than strains isolated from community-acquired infections (1.5%). The results highlighted that lasB (98.7%) and exoS (98.7%) were the most frequent virulence genes. This survey provides data about phenotypic and genotypic properties of Pseudomonas aeruginosa emerged in the Northwestern of Morocco. It could be helpful for the health workers to improve infection control measures and to establish a surveillance system.

635. Genomic Evolution and Progression of Antimicrobial Resistance in a Series of Extensively Drug-Resistant Pseudomonas aeruginosa (XDR-Pa) Isolates from a Cystic Fibrosis Lung Transplant Recipient

BackgroundChronic respiratory infection due to extensively drug-resistant Pseudomonas aeruginosa (XDR-Pa) is a significant cause of mortality in cystic fibrosis (CF) patients. The CF respiratory anatomy, chronic antibiotic use, and PA colonization creates a milieu for high evolutionary pressure and genetic diversity. We sought to explore the progression of antibiotic resistance and genome evolution of XDR-Pa in a longitudinal series of isolates collected from an18-year-old CF patient who underwent lung transplantation.MethodsConsecutive respiratory isolates were collected from December 2016 to March 2018. Standard disk diffusion methods were used to evaluate antimicrobial susceptibility. Whole-genome sequencing (WGS) data were obtained on an Illumina NextSeq and assembled. Variants were identified using the GATK HaplotypeCaller and their functional impact was determined using snpEff. Maximum likelihood phylogenetic trees were constructed using MEGA and BEAST. Panther was used to test for enrichment of Gene Ontology functional categories among mutated genes.ResultsPhylogenetic analysis of complete genome sequences showed that 18 isolates formed a monophyletic group. Analysis using BEAST showed that genomes shared a common ancestor that was present prior to transplant. Over 300 single nucleotide variants and small insertion-deletion mutations were found, in comparison with a reconstruction of the ancestral sequence (Figure 1). Shared patterns of antibiotic susceptibility profiles were largely concordant with phylogenetic clustering and trended toward a decrease in susceptibility over time. Two different frameshift mutations in the DNA mismatch repair gene mutL were found in 15 genomes and these exhibited an increased rate of transition to transversion mutations, consistent with a hypermutator phenotype.ConclusionWGS of XDR-Pa identified variations in antibiotic resistance and virulence genes. Changes in mutL likely accelerated the accumulation of mutations. Multiple related sub-groups of strains appear to have been circulating prior to transplant and continued to diverge during the treatment period. Correlating antibiotic pressure, susceptibility profiles, and WGS in XDR-Pa from a single patient reveals the clinical impact of genomic evolution in CF. Disclosures All authors: No reported disclosures.

English

Limited treated options to Salmonellosis exist due to the emergence of extended spectrum beta lactamases (ESBLs). This study determined the prevalence of common ESBL genes (blaSHV, blaCTX-M, blaOXA) and profiled their antimicrobial resistance drug pattern. A descriptive cross-sectional study that involved 16 Salmonella enterica isolates from diarrhoeic children at the University of Calabar Teaching Hospital and 39 isolates from healthy birds in poultry farms within the Calabar metropolis. Standard disc diffusion method determined antimicrobial susceptibility while Polymerase Chain Reaction (PCR) using specific primers identified the beta-lactamase genes. All 55 isolates phenotypically demonstrated ESBL production. All 55 salmonella isolates were resistant to Cefotaxime and Nalixidic acid. All the clinical isolates were susceptible Ciprofloxacin and Norflaxacin. The poultry isolates however exhibited varied degrees of resistance to Ciprofloxacin and Norflaxacin. All 55 Salmonella isolates carried the blaSHV genes, blaCTX-M gene (94.5%) blaOXA gene (18.2%). Molecular characterization identified the blaSHV gene as the most prominent. This study provides relevant data that would help in the implementation of policies regarding the use of antimicrobial agents in clinical and veterinary settings as well provide antimicrobial treatment guidelines that would strengthen infection control processes. Key words: Salmonella enterica, Antimicrobial-resistance, ESBL-genes, Poultry-sources.

Molecular Detection ctx-M, TEM and VIM in ESBL-Producing E. coli Strains Isolated from Pregnant Women in Osogbo

Urinary tract infection (UTI) is a major bacterial infection causing serious health problem in pregnant women. The physiological and anatomical changes in pregnancy facilitate urinary tract infection (UTI) during pregnancy. Asymptomatic bacteriuria in pregnancy is associated with pyelonephritis, preterm labour and low birth weight infants. The study was designed to characterise phenotypically and genetically the major organism associated with UTI among pregnant women in Osun State. A cross-sectional study design was used to collect mid-stream urine samples between March 2018 to September 2018 from 150 pregnant and 50 non-pregnant women which serve as control. Samples were inoculated into Cysteine Lactose Electrolyte Deficient (CLED) medium, subcultured onto MacConkey and Blood agar plates. A standard agar disc diffusion method was used to determine antimicrobial susceptibility pattern of the isolates and the molecular detection of the antibiotic resistant genes were done. Data were subjected to descriptive statistics. The ages of women enrolled in this study ranges from 22 to 43 years (mean ± standard deviation = 25 ± 4.7 years). The predominant bacteria identified were E. coli (34.5%), S. aureus (10.3%), coagulase negative Staphylococci [CoNS] (17.2%), Klebsiella species (6.9%) and Enterobacter species (31.0%). Majority of Gram-negative bacteria isolates were resistant to ampicillin (70%), cefotaxime (62%), while 75–100% of the Gram positive isolates were resistant to ampicillin. Multiple drug resistance was observed, all the E. coli isolates were resistant to Cefotaxime, meropenem and ampicillin. Of E. coli isolates, 4, 3 and 6 were positive for the VIM, ctx-M and TEM genes respectively.Similarly, the risk of UTI was higher in those had previous UTI history (OR = 2.29, 95% CI = 1.15–4.56, P = 0.019) as compared to those who had no previous history of UTI.

QSAR Study of Some 1,3-Oxazolylphosphonium Derivatives as New Potent Anti-Candida Agents and Their Toxicity Evaluation.

The incidence of invasive fungal infections caused by Candida spp. has increased continuously in recent decades, especially in populations of immunocompromised patients or individuals hospitalized with serious underlying diseases. Therefore, the goal of our study was the search for new potent Candida albicans inhibitors via the development of QSAR models that could speed up this search process. A number of the most promising 1,3-oxazol-4-yltriphenylphosphonium derivatives with predicted activities were synthesized and experimentally tested. Furthermore, the toxicity of the studied compounds was determined in vitro using acetylcholinesterase enzyme as a biological marker. The classification QSAR models were created using Random Forests (WEKA-RF), k-Nearest Neighbors and Associative Neural Networks methods and different combinations of descriptors on the Online Chemical Modeling Environment (OCHEM) platform. Аntifungal properties of the investigated compounds were performed using standard disk diffusion method. The enzyme inhibitory action of the compounds was determined by modified Ellman's method using acetylcholinesterase from the electric organ of Electrophorus electricus. Three classification QSAR models were developed by the WEKA-RF, k-NN and ASNN methods using the ALogPS, E-State indices and Dragon v.7 descriptors. The predictive ability of the models was tested through cross-validation, giving a balanced accuracy BA = 80-91%. All compounds demonstrated good antifungal properties against Candida spp. and slight inhibition of the acetylcholinesterase activity. The high percentage of coincidence between the QSAR predictions and the experimental results confirmed the high predictive power of the developed QSAR models that can be applied as tools for finding new potential inhibitors against Candida spp. Furthermore, 1,3-oxazol-4- yl(triphenyl)phosphonium salts could be considered as promising candidates for the treatment of candidiasis and the disinfection of medical equipment.

Inhibition of the growth of human dermatophytic pathogens by selected australian and asian plants traditionally used to treat fungal infections

ObjectiveSyzygium australe (H.L. Wnddl. ex. Link) B. Hyland, Syzygium luehmannii (F. Muell.) L.A.S. Johnson, Syzygium jambos L. (Alston), Terminalia ferdinandiana Exell. and Tasmannia lanceolata (Poir.) A.C.Sm. are used in traditional Australian Aboriginal and Asian healing systems to treat a variety of pathogenic diseases including fungal skin infections, yet they are yet to be examined for the ability to inhibit the growth of human dermatophytes. Materials and methodsThe fungal growth inhibitory activity of extracts produced from selected Australian and Asian plants was assessed against a panel of human dermatophytes by standard disc diffusion and liquid dilution MIC methods. The toxicity of the extracts was evaluated by Artemia lethality and MTS HDF cell viability assays. The phytochemistry of the most promising extracts were examined by GC-MS headspace analysis and some interesting compounds were highlighted. ResultsThe aqueous and methanolic extracts of all plant species were good antifungal agents, inhibiting the growth of all of the dematophytes tested. The methanolic S. australe (SA) and S. luehmannii (SL) extracts were particularly potent fungal growth inhibitors. MIC values of 39 and 53μg/mL were recorded for the methanolic SL fruit extract against T. mentagrophytes and T. rubrum respectively. Similar MICs were also noted for the methanolic SL leaf extract (88 and 106μg/mL respectively). The methanolic SL leaf extract was a particularly good fungal growth inhibitor, with MIC values≤100μg/mL against the reference C. albicans strain (96μg/mL), E. floccosum (53μg/mL), and T. mentagrophytes (88μg/mL). This extract also produced MICs≤200μg/mL against all other fungal species/strains tested. Similarly good activity was seen for the methanolic S. australe leaf and fruit extracts, as well as the S. lehmannii fruit and S. jambos leaf extracts, with MIC values 100-500μg/mL. Interestingly, these extracts had low toxicity and high therapeutic indices, indicating their suitability for clinical use. GC-MS headspace analysis highlighted several monoterpenoids and sesquiterpenoids in the methanolic SA and SL extracts. T. ferdinandiana and T. lanceolata extracts also had promising antifungal activity, albeit with substantially higher MICs. ConclusionWhilst multiple extracts inhibited fungal growth, the methanolic S. australe and S. luehmannii leaf extracts and the S. luehmannii fruit extracts showed particularly potent activity against each of these dermatophytes, indicating that they are promising leads for the development of anti-dermatophytic therapeutics.

Evaluating the Effects of Peracetic Acid and Chlorine Dioxide Disinfectants on Staphylococcus Aureus Isolated from Surfaces of NICU

Introduction: Today, disinfection of surfaces by using antimicrobial agents is critical for the prevention and control of pathogens and reduction of infection in hospital. The aim of this study was to investigate and compare the effects of two disinfectants against Staphylococcus aureus isolated from the NICU of Shahid Sadoughi Hospital of Yazd in 2017. Materials and Methods: In this descriptive cross sectional study, bacterial culture of samples collected from different surfaces of the NICU and S. aureus isolates were identified using conventional biochemical tests. Peracetic acid and chlorine dioxide various concentrations were used as disinfectants. Their effects against Staphylococcus aureus were determined by Standard disc diffusion method. Data were analyzed by linear mixed models in SPSS version 23. Results: 39.39% of samples were found to be S. aureus infected. The mean diameter of growth inhibition zone for peracetic acid 0.1% was significantly lower than that for peracetic acid 0.2%, and peracetic acid 0.1% was significantly higher than that for chlorine dioxide (P < 0.001). The comparison of growth inhibition zone diameters for peracetic acid 0.1% and chlorine dioxide disinfectants showed that the average diameter of the inhibition zone created by peracetic acid 0.1% was significantly higher than that created by chlorine dioxide. The most effective disinfectant on S. aureus strains isolated was peracetic acid 0.2% and the least effective disinfectant was chlorine dioxide. Conclusion: In health care facilities with S. aureus infection, peracetic acid 0.2% can be used effectively to reduce nosocomial infection rate.

Antifungal Susceptibility of Malassezia pachydermatis Isolates from Dogs

Abstract The genus Malassezia belongs to Basidiomycota and includes 16 species, from which M. pachydermatis is the most common in dogs. M. pachydermatis is a member of the normal mycobiota of the skin and mucosal sites of dogs. Under certain conditions, these yeasts can be opportunistic pathogens and involved skin and ear canal infections of these animals. Topical and oral antifungal agents are used for the therapy of Malassezia dermatitis and otitis. With the expanding use of antifungal agents, resistant strains of Malassezia are increasingly detected. In this study, the susceptibility of 40 M. pachydermatis isolates to fluconazole, itraconazole, ketoconazole, clotrimazole and nystatin were evaluated in vitro based on the modified standard disk diffusion method M44-2A.

Antibiotic resistance patterns of urinary tract infections in the West of Iran

Introduction: Urinary tract infection is one of the most common infections. About 10% of people experience it in their lifetime. Due to the significant increase in antibiotic resistance and the unpredictability of antibiotic susceptibility of pathogens, the availability of antibiotic susceptibility testing results can be useful in the selection of the antibiotics based on the type and pattern of antibiotic resistance of the pathogen. Objectives: The aim of this study was to determine the antibiotic resistance pattern of bacteria producing urinary tract infection in Sanandaj, Iran. Materials and Methods: This cross-sectional study was performed on 3126 urinary samples from Tohid hospital in Sanandaj University of medical sciences in 2017. The urine specimens were cultured on EBM (Eosin Methylene Blue) and blood agar media. Kirby-Bauer’s standard disk diffusion method was applied to test the susceptibility of the drug for Mueller-Hinton culture agar plates. The results were extracted based on the criteria of CLSL (Clinical and Laboratory Standards Institute). Results: In the study of the samples, the results of 708 cultures (22.64%) were positive. Among the urinary pathogens, Escherichia coli with 291 cases (41/10%) was the most common isolated bacteria. According to the results of antibiogram, the highest antibiotic resistance was observed for cefixime (92.51%), ceftriaxone (52.54%) and cotrimoxazole (45.48%). The highest antibiotic sensitivity was observed for imipenem (96.11%), nitrofurantoin (91.67%) and ceftazidime (88.28%). Conclusion: According to this study, the highest antibiotic resistance was observed with cefixime, ceftriaxone and cotrimoxazole that these drugs are not recommended as the first line of antibiotic therapy. On the other hand, the highest antibiotic susceptibility was observed with Imipenem, nitrofurantoin and ceftazidime, which should be considered in the treatment of urinary tract infections.

Antibiotic sensitivity profile and resistance of microorganisms isolated from south Indian population, a hospital based study at Velappanchavady, Chennai, India

Background: Increasing rates of antibiotic drug resistance has been noted in recent times and this adversely affects the prognosis and outcomes of patients. There is a greater need for local resistance prevalence data in order to guide empirical prescription and to identify areas in which medical need for newer antimicrobial agents is greater.Methods: A prospective hospital based observational study was carried out to determine antibiotic sensitivity profile and resistance pattern of microorganisms. Samples were collected from urinary tract infections, while cultures from blood stream infections, sputum samples and Serology. Antibiotic susceptibility was determined by the standard disc diffusion method. Data interpretation was based on CLSI, 2017 guidelines for antimicrobial susceptibility testing.Results: The predominant isolates from the samples were, Staphylococcus aureus (16.7%) 67, K. pneumoniae (11.5%) 46, E. coli (29.4%) 118, P. aeruginosa (6%) 24. Escherichia coli, the most common causative organism showed high resistance to commonly used drugs such as Ampicillin (60.1%) 71, Amoxicillin (53.4%) 63, Amoxicillin-clavulanic acid (44.1%) 52 and Nalidixic acid (53.4%) 63. E. coli was found to be most sensitive to Amikacin (51.7%) 61, Piperacillin (69.5%) 82, Norfloxacin (61.9%) 73, Meropenem (76.3%) 90 and Imipenem (68.6%) 81. Klebsiella was most sensitive to 30 (65.2%) ofloxacin, 31 (67.4%) ciprofloxacin followed by 24 (52.2%) ceftriaxone and least sensitive to 7 (15.2%) Amoxicillin and 12 (26.1%) Ampicillin.Conclusions: Among commonly used antibiotics resistance to Penicillins (Ampicillin, Amoxicillin) was highest. Resistance to Fluoroquinolones (Ciprofloxacin) was seen in majority of the patients. Among broad spectrum antibiotics Imipenem, Meropenem resistance was seen in lesser proportion of the patients.

Presence of virulence factors and antibiotic resistance among Escherichia coli strains isolated from human pit sludge.

In Bangladesh, human sludge from dry pit latrines is commonly applied directly to agricultural lands as manure. This study was conducted to investigate the presence of antibiotic resistance, virulence factors and plasmid contents of E. coli strains isolated from sludge samples. E. coli were isolated from human feces from closed pit latrines and identified by culture method. Antibiotic susceptibility patterns of the isolates were determined by Standard Kirby-Bauer disk diffusion method. Pathogenic genes and antibiotic resistance genes of ESBL producing isolates were determined by PCR assay. Of the 34 samples tested, 76.5% contained E. coli. Of 72 E. coli isolates, 76.4% were resistant to at least one of the 12 antibiotics tested and 47.2% isolates were resistant to three or four classes of antibiotics. Around 18% isolates were extended spectrum β- lactamase producing and of them 6 were positive for blaTEM specific gene, 4 for blaCTX-M gene, 1 for blaOXA gene and 2 for both blaTEM and blaCTX-M genes. Moreover, among 72 isolates, 4.2% carried virulence genes of enterotoxigenic E. coli; two isolates were positive for st and one was positive for both st and lt genes. In addition, 59.7% of the isolates contained plasmids (range 1.4 to 140 MDa) of which 19.5% isolates contained a single plasmid and 40.2% contained multiple plasmids. The presence of pathogenic, drug resistant E. coli in human sludge necessitates a regular surveillance before using as a biofertilizer.

Interactive antimicrobial and toxicity profiles of Pittosporum angustifolium Lodd. extracts with conventional antimicrobials

ObjectivePittosporum angustifolium Lodd. is used to treat a variety of pathogenic diseases and inflammation by Australian aborigines. Practitioners of complementary medicine frequently use herbal medicines concurrently with conventional antibiotics. There is a need to evaluate their effects in combination. MethodsThe bacterial growth inhibitory activity of P. angustifolium leaf extracts was assessed against a panel of pathogenic triggers of some autoimmune diseases by standard disc diffusion and liquid dilution minimum inhibitory concentration (MIC) methods. Combinational effects between the extracts and conventional antimicrobials were classified using the sum of the fractional inhibitory concentration. Synergistic interactions were further assessed across a range of ratios by isobologram analysis. The toxicity of the individual samples and combinations was evaluated by Artemia lethality and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) human dermal fibroblast cell viability assays. ResultsP. angustifolium leaf extracts strongly inhibited the growth of several bacterial triggers of autoimmune diseases. The methanolic, aqueous and ethyl acetate extracts were particularly good inhibitors of Proteus mirabilis and Klebsiella pneumonia growth (MIC = 26 and 57 µg/mL respectively). Some combinations of the extracts and conventional antibiotics significantly potentiated the combined inhibitory activity compared to the individual components. Of the 250 combinations studied, approximately 0.02% showed synergistic interactions, 49.6% were additive, 46.8% showed indifferent interactions and antagonism occurred in only 0.02% of the combinations. Interestingly, all of the synergistic and antagonistic combinations contained tetracycline as their antibiotic component. ConclusionP. angustifolium leaf extracts inhibit the growth of pathogenic triggers of some autoimmune diseases. Some extracts also potentiated the activity of conventional antibiotics, without significantly affecting the toxicity of the combination.

Antibiotic Resistance Profiling and Molecular Phylogeny of Biofilm Forming Bacteria From Clinical and Non-clinical Environment in Southern Part of Bangladesh

Background: Biofilm is a surface adhered extracellular polymer matrix produced by bacteria. The establishment of biofilms is considered as an important pathogenic trait in many chronic infections and antibiotic resistance. Objective: The present study was intended to evaluate biofilm forming potency and antibiotic resistance (AR) pattern in clinical and non-clinical bacterial isolates, and their phylogenetic characterization. Materials and Methods: A total of 82 bacterial isolates were obtained from clinical settings and animal farms from southern (Kushtia-Jhenaidah) region of Bangladesh. Biofilm forming potentials and AR profile were evaluated by standard biofilm assay and Kirby-Bauer disk diffusion method, respectively. Further, antibiotic exposure was assessed by multiple antibiotic resistance (MAR) value indexing. Furthermore, statistical methods were applied to estimate the relationship between AR and biofilm formation. Finally, selected isolates were characterized by morphological and biochemical tests, as well as 16S rRNA gene sequencing. Results: Clinical isolates showed higher biofilm formation (OD595=1.17±0.03) than non-clinical isolates (OD595=0.68±0.03). Among all, Pseudomonas isolates produced the highest amount of biofilms (OD595=2.08±0.02). The AR profiles fell within 46.67-86.67% and MAR index ranged from 0.47 to 0.87. Moreover, a significant positive correlation (P<0.05) was found between biofilm formation and AR. Eventually, heavy biofilm producers with ≥60% resistance profile were characterized and identified as Escherichia coli, Cronobacter sakazakii, Pseudomonas aeruginosa, Staphylococcus sciuri, and Staphylococcus aureus. Conclusion: In general, biofilm formation and MAR were highly correlated regardless of the source, type, and environment of the isolates. Therefore, a rigorous evaluation of both biofilm formation and AR is demanded to minimize AR and associated problems.

Anti-microbial Resistance Pattern of Uropathogens Isolated from Hospitalized Patients in Imam Khomeini hospital, Tehran, Iran

Background: Urinary tract infection (UTI) is one of the most common type of bacterial infectious diseases which occurs in all age groups. The aim of this study was to determine anti-microbial resistance pattern of bacterial pathogens causing UTIs in hospitalized patients at the Imam Khomeini Hospital, Tehran, Iran. Material and Methods: Urine samples were collected from 11157 hospitalized patients at different wards of Imam Khomeini Hospital in Tehran, between January 2015 and December 2015.The cultured plates were assessed for significant bacterial growth. Anti-microbial susceptibility test was performed using standard disk diffusion method. Results: Out of the 11157 collected urine samples, significant bacterial growth of 25.38% was observed. The most common cause of UTI was gram-negative bacteria (82.2%). More than 50% of the gram-negative bacteria were resistant to ceftriaxone, ceftazidime and trimethoprim-sulfamethoxazole. Enterococcus spp. (10.1%) was found as the third causative agent of UTIs and the most common gram-positive bacteria. Conclusion: we conclude that the examination of the most common etiological agent of UTIs and their antimicrobial resistance patterns is advantageous and necessary in order to design a guideline for empirical therapy.

EVALUATION OF ANTIOXIDANT, ANTIMICROBIAL, AND ANTIFUNGAL POTENTIAL OF CUCURBITA PEPO VAR. FASTIGATA SEED EXTRACTS

Objective: The current study aims to study the antioxidant and antimicrobial and antifungal potential of the methanolic extract of Cucurbita pepo var. fastigata seeds (MECS).
 Methods: Extraction of the seeds has been carried out with solvents of increasing polarity (chloroform, acetone, and methanol) and the phytochemical study of the methanolic extract have been carried out using standard methods. The free radical scavenging activity of all the extracts was evaluated by DPPH and H2O2 methods. Standard disk diffusion method was used to evaluate antibacterial and antifungal activities.
 Results: Phytochemical evaluation showed the maximum presence of triterpenoids, phenolic compounds, tannins and small amount of Coumarins. Methanolic extract revealed momentous antioxidant activity as compared to chloroform and ethyl acetate extract. Hence, methanolic extract of C. pepo. seeds (MECS) at a dose level of 100, 200 and 300 μg/ml was evaluated for antioxidant potential. Maximum free radical scavenging activity of methanolic seed extract of cucurbita pepo var. fastigata has been found at a dose of 300 μg/ml to be 63±0.16 % by 1,1-diphenyl-2-picryl hydrazyl model and at a value of 78% at 300 μg/ml with H2O2 model. Methanolic extract also showed the presence of antibacterial activity.
 Conclusion: Presence of phytochemicals in the methanolic extract is responsible for the antioxidant potential. Extracts were investigated for antibacterial activity using the standard disc diffusion assay method against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa and for the antifungal activities against Aspergillus niger and Candida albicans. The seed extract showed the presence of antibacterial activity, but the antifungal activity was found to be absent in the extract.

Anticoagulant, thrombolytic and antibacterial activities of Euphorbia acruensis latex-mediated bioengineered silver nanoparticles

Abstract In this report, we present a simple and unexplored procedure for green synthesis of silver nanoparticles featuring exudation of Euphorbia acruensis along with the study of its antibacterial and anticoagulant properties. Analytical techniques like ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) were used to analyse the production, crystallinity and morphology of bio-reduced silver nanoparticles. The antibacterial study was performed by following standard disc diffusion method. Most importantly, the anticoagulant and thrombolytic activities of biogenic silver nanoparticles were evaluated by addition of nanoparticles to human blood samples under practical conditions. These green synthesized silver nanoparticles were found to have potent antibacterial, anticoagulant and thrombolytic properties which make them an attractive choice for future medical applications.

Expression of dnak, groES and cps genes in irradiated Klebsiella pneumoniae strains isolated from UTI Egyptian patients

T his investigati on presents a brief study for monitoring the correlation between the expression of heat-shock protein (HSP) genes; dnak, and groES as well as the capsular polysaccharide (caps) gene and antimicrobial susceptibility of extensively drug resistant (XDR) Klebsiella pneumoniae in response to a low dose of Gamma (γ) radiation. The XDR K. pneumoniae strains, that were obtained from (UTI) Egyptian patients were identified using the API 20E strip automated system. Their antimicrobial susceptibilities were monitored using standard disc diffusion method in parallel with their minimum inhibition concentrations (MICs) towards standard antibiotics using a micro-titer method, before and after exposure to γ-radiation at a dose of 24.4 Gray (Gy). The expression of dnak, groES, and cps genes was detected by qRT-PCR under the same conditions. The results demonstrate increasing antibiotic resistance after exposure to γ-radiation. Also, a doubling in the MIC of the tested strains towards CAZ(ceftazidime) was observed. These results were confirmed by an elevation in the expression of dnak, groES, and cps genes in response to γ-radiation. These preliminary results need more confirmaions, because they assume difficulties in curing immunocompromised patients infected with XDR K. pneumoniae by the currently available antibiotics.

Assessment of the antibacterial potential of Aloe vera as a source of antibacterial agents

Background: Nowadays the use of herbs as an alternative to the chemical drug is considered by researchers. Aloe vera belongs to the Asphodelaceae family, a medicinal plant that has been used since ancient times for different pharmaceutical products. This study aimed to evaluate the antibacterial properties of Aloe vera grown in Khouzestan, southwest of Iran. Materials and Methods:For this purpose, ethanol extract was prepared from aerial parts of Aloe vera and its activity was tested against some gram-positive (Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus) and gram-negative (Pseudomonass aeruginosa, Salmonella Typhi, Proteus mirabilis) bacterial species through standard Kirby-Bauer disc diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration were also investigated. Results: The Aloe vera extract showed antibacterial activity against the majority of bacteria. The highest activity (about 25mm inhibition zone) happened against P. aeruginosa but it did not show any inhibitory activity against S.aureus and P. mirabilis. The MIC was found as 10 mg/ml while MBC ≥ 80. Conclusion: Based on the results of this study it can be suggested that Aloe vera contains active antibacterial substances that can be used efficiently for bacterial pathogen control and it should be considered as a potent antimicrobial source for finding new antibiotics, especially against resistant species.