دراسة تأثير مستخلص قشور القرع النانوي في تثبيط فعالية بعض الأحياء المجهرية

1281. An Evaluation of Tebipenem In Vitro Activity Against a Panel of Pseudomonas aeruginosa Isolates with Efflux, AmpC, and OprD Mutations

BackgroundFosfomycin combination therapy is a potential approach for treatment of multidrug-resistant (MDR) PA infections despite a lack of approved susceptibility breakpoints for this organism. While DD testing is commonly used for fosfomycin, growth of discrete inner colonies (IC) within the zone of inhibition has been observed for multiple organisms following DD. Criteria recommended by CLSI and EUCAST are contradictory for interpreting these inner colonies. We therefore sought to determine the frequency of inner colonies and MIC differences between PA parent-inner colony pairs from an international isolate collection.MethodsA convenience collection of 198 clinical PA isolates from three U.S institutions (n = 82), two Australian institutions (n = 72), and the CDC & FDA Antibiotic Resistance Isolate Bank (n = 44) were included. Fosfomycin MIC values were determined in duplicate on separate days by DD and broth microdilution (BMD) testing. For parent isolates with discrete IC observed during DD, IC isolates were subcultured and MIC values were determined and then compared to their corresponding parent isolates. MIC values were interpreted using CLSI Escherichia coli (EC) breakpoints (susceptible: MIC ≤ 64 μg/mL, intermediate: MIC = 128, resistant: MIC ≥ 256 μg/mL).ResultsParent isolate BMD MIC values ranged from < 4 to > 256 μg/mL while IC isolate BMD MIC values ranged from 128 to > 1024 μg/mL. MIC50/90 values were 128/256 μg/mL and > 1024/ > 1024 μg/mL for the parent and IC isolates, respectively. A high frequency of 45% (89/198) of parent isolates displayed discrete IC which also demonstrated a higher frequency of resistance (97.8%) compared to the parent isolates (23.7%).ConclusionIC MIC values were higher overall compared to parent MIC values, with an average fold difference of ~18 between the parent-inner colony pairs. The frequency of IC found in this study (45%) is considerably higher than previously observed in EC clinical isolates. These data highlight the need to further investigate the importance of these IC and warrant caution for extrapolation of EC breakpoints for fosfomycin susceptibility testing against PA.DisclosuresAll Authors: No reported disclosures

OBJECTIVE: To evaluate the antibacterial potential of aqueous and acetone extracts of galls of <i>Quercus infectoria</i> by determination of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values. <br>MATERIALS AND METHODS: The extracts from the galls of <i>Q. infectoria</i> at 10 mg/ml were screened against three Gram-positive bacteria (<i>Staphylococcus aureus</i> ATCC 25923, <i>Staphylococcus epidermidis</i> and<i> Bacillus subtilis</i>) and three Gram-negative bacteria (<i>Escherichia coli </i>NCTC 12079 serotype O157:H7, <i>Salmonella typhimurium</i> NCTC 74 and <i>Pseudomonas aeruginosa</i> ATCC 27853). The MIC of the extracts were then determined using the twofold serial microdilution technique at a concentration ranging from 5 mg/ml to 0.0024 mg/ml. The MBC values were finally obtained from the MIC microtiter wells which showed no turbidity after 24 hrs of incubation by subculturing method. <br>RESULTS: Out of the six bacterial species tested, <i>S. aureus</i> was the most susceptible. On the other hand, the extracts showed weak inhibitory effect against <i>S. epidermidis, B. subtilis</i>, <i>S. typhimurium</i> and <i>P. aeruginosa</i> while there was no inhibition zone observed for <i>E. coli </i>O157. The MIC values of the extracts ranged from 0.0781 mg/ml to 1.25 mg/ml whereas the MBC values ranged from 0.3125 mg/ml to 2.50 mg/ml. The MBC values of aqueous extract against <i>S. aureus</i> and <i>S. typhimurium</i> were higher than their MIC values. The MBC value of acetone extract against <i>S. aureus</i> was also higher than its MIC value. Interestingly, however, the MIC and MBC values of acetone extract against <i>S. typhimurium</i> were the same (1.25 mg/ml). <br>CONCLUSION: The aqueous and acetone extracts displayed similarities in their antimicrobial activity on the bacterial species and as such, the galls of <i>Quercus infectoria</i> are potentially good source of antimicrobial agents.

Background: Artemisia indica is a traditionally used medicinal plant in the treatment of various conditions such as loss of appetite, abdominal discomfort, antimalarial infection, dermal wound infection, etc. Objectives: This study aims to determine the presence of phytochemical content, antioxidant, antibacterial, and antidandruff activity of leaf extract of A. indica . Materials and Methods: Dried ground leaves were subjected to a cold extraction method using an absolute concentration of methanol, ethanol, and water. Total phenolic, flavonoid, and proanthocyanidin content was estimated by using a linear regression equation from the calibration curve and expressed in terms of gallic acid equivalent (GAE) and rutin equivalent (RE). Antioxidant properties were determined using DPPH (1,1-diphenyl-2-picryl-hydrazyl), nitric oxide, and hydrogen peroxide assay, and their IC 50 values were calculated. The antibacterial activity was tested using the agar well diffusion method against the common five pathogenic strains, and the zone of inhibition is compared with gentamicin (1 mg/mL) as a positive control. The minimum inhibitory concentration (MIC) value was obtained by the microbroth dilution method. The antidandruff assay was performed on Malassezia furfur by the disk diffusion method into Sabouraud dextrose agar overlaid with 1 mL of olive oil, and the MIC value was determined by the microtiter plate method. Results: The result showed that the Artemisia methanolic extract represents ample content of phenolics (248±3.29 mg/g of GAE), flavonoids (222.33±4.41 mg/g of RE), and proanthocyanidin (222.83±1.62 mg/g of RE equivalent). The antioxidant assay revealed that methanolic extract has the highest radical scavenging activity followed by aqueous extract and then ethanolic extract. The antibacterial activity of leaf extract shows MIC value ranging from 6 to 25 μg/mL against various human pathogenic bacteria. The antidandruff assay showed that MIC value of methanolic extract is lesser than that of ethanolic extract (350&lt;400) mg/mL. Conclusion: The results concluded that leaf extract of A. indica contains phenolics, flavonoids, and proanthocyanidin and exhibits adequate antibacterial, antidandruff, and antioxidant activity.

Recent data show an emergence of resistance in the Bacteroides fragilis group against several antimicrobial agents and inducible resistance against metronidazole in nim-positive strains. The aim of the present study was to investigate inducible metronidazole resistance in nim-positive as well as in nim-negative B. fragilis group strains. Of 18 B. fragilis strains (including four nim-positive reference strains and one ATCC strain), two Bacteroides ovatus strains, and one Bacteroides thetaiotaomicron DSM strain minimum inhibitory concentration (MIC) values for metronidazole were determined by Etest and analyzed for nim genes (nimA to -G) by PCR. For this purpose bacterial suspensions were incubated on supplemented Columbia agar plates containing metronidazole at twice the MIC value of the specific strain and incubated under anaerobic conditions for 48 hours. After incubation, growing bacteria were harvested and thereafter incubated at four times the original MIC. This procedure was repeated with increasing antibiotic concentrations. The resulting MIC values were confirmed by Etest. The MIC values for metronidazole of the four nim-positive reference strains ranged from 3 to 8 mg/l. The B. fragilis ATCC 25285 strain and the B. thetaiotaomicron DSM 2255 strain were nim negative with MIC values of 0.19 mg/l and 0.75 mg/l, respectively. Three clinical isolates of B. fragilis strains showed MIC values of > 256 mg/l. In all three strains, nim genes were detected by PCR. The other clinical isolates were nim negative. In these strains, MIC values ranged from 0.19 to 0.75 mg/l. After several passages on metronidazole containing agar, all B. fragilis group strains exhibited MIC values of > 256 mg/l determined by Etest. Metronidazole resistance can be selected not only in nim-positive strains but also in nim-negative strains, suggesting that mechanisms other than nim genes are involved. These findings and the emerging resistance of the B. fragilis group against several antimicrobial agents underscore the importance of susceptibility testing of anaerobes even in routine laboratories.

Introduction: The primary aetiology of chronic periapical abscesses, including E. faecalis, S. mutans, S. sanguinis, and P. gingivalis, can be eliminated using intracanal medicaments such as calcium hydroxide. The purpose of this study was to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) value of calcium hydroxide paste in the vulnerable initial 7-day of treatment against E. faecalis ATCC 29212, S. mutans ATCC 25175, S. sanguinis ATCC 10556, and P. gingivalis ATCC 33277. Methods: An in-vitro laboratory experiment using a spectrophotometer as a microdilution method was conducted to determine bacteria's MIC and MBC values on calcium hydroxide paste. The sample used in this study was four bacteria using intracanal medicament of calcium hydroxide (Ca(OH)2), incubated for seven days at 37°C, and then bacterial growth was observed. The cell inhibition percentage was calculated using optical density measurements to determine the MIC value. The low MIC and MBC were defined as sensitive bacteria to calcium hydroxide. Results: Calcium hydroxide paste against E. faecalis (ATCC 29212) with MIC values at a concentration of 750 μg/ml and MBC values at a concentration of 96,000 μg ml; S. mutans (ATCC 25175) with MIC value at a concentration of 3,000 ug/ml and MBC value at a concentration of 48,000 ug/ml; S. sanguinis (ATCC 10556) with MIC value at a concentration of 3,000 ug/ml and MBC value at a concentration of 6,000 ug/ml; P. gingivalis (ATCC 33277) with MIC value at a concentration of 6,000 ug/ml and MBC value at a concentration of 48,000 ug ml. Conclusions: Calcium hydroxide can inhibit bacterial growth activity. E. faecalis (ATCC 29212) and S. sanguinis (ATCC 10556) are more sensitive to calcium hydroxide paste than other bacteria, with the lowest MIC and MBC on seven days of incubation since the maximum calcium and hydroxyl ions are released.

Medicinal plants are the oldest known source for treatment of disease. Using pharmaceutical plants and plant extracts have been at great attention. In this research, the antibacterial activity of the methanolic and aqueous extracts of three Iranian medicinal plant species namely Capparis spinosa L., Adiantum capillus-veneris L. and Sambucus ebulus L. were tested against six bacteria strains including (Staphylococcus aureus , Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa ). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for each plant were determined by microdilution method. The maximum antimicrobial activity of aqueous extracts was exhibited by S. ebulus . The methanolic extract of S. ebulus had the best MIC values against S. epidermidis, S . aureus , B. subtilis and K. pneumonia (25, 50, 100 and 100 mg/ml, respectively) and the methanolic extract of A. capillus-veneris had the best MIC value against S. aureus and S. epidermidis (12.5 and 50 mg/ml) and the methanolic extract of C. spinosa had the best MIC value against E. coli (100 mg/ml). Key words: Sambucus ebulus , Adiantum capillus-veneris, Capparis spinosa, Antibacterial effects, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). INTRODUCTION The use of medicinal plants as a source for relief from illness can be traced back over five millennia to written documents of the early civilization in Iran, India and China. In recent years, multiple drug resistance in human has been developed due to indiscriminate use of commercial antibacterial drugs commonly used in the treatment of infectious diseases. This situation has forced scientists to search new antibacterial agents in various sources like medicinal plants (Kumar et al., 2006). Plants are used medicinally in different countries and are a source of many potent and powerful drugs (Jeyachardran et al., 2010). Adiantum capillus-veneris L and Sambucus ebulus L. grow in the northern regions of Iran especially in the

The occurrence of resistant bacteria to specific heavy metals can be associated with increasing load of the metals in the environment. River Yamuna is polluted by various toxic heavy metals discharged by several industrial and agricultural sources. Therefore, the use of heavy metal-resistant bacteria as an indicator of metal pollution was tested in the present study. For the purpose of the study, the heavy metal resistance status of 42 Escherichia coli strains isolated from River Yamuna water from 7 sampling sites within a span of 2years was determined using growth curves and plate dilution method in terms of minimum inhibitory concentration (MIC) values by comparing with MIC value of control strain. Seasonally, the lowest mean MIC value was observed for bacterial strains isolated in post-monsoon (December) 2013 and highest mean MIC value was observed for bacterial strains isolated in monsoon (August) 2015. Site-wise analysis of the maximum mean MIC values for all the isolated strains showed the highest mean Ni MIC value for the bacterial strains isolated from site S4 (ITO), highest mean Cu MIC, Cr MIC, and Fe MIC values for the bacterial strains isolated from site S2 (Najafgarh drain intermixing zone) and highest mean Cd MIC, Pb MIC, and Zn MIC values for the bacterial strains isolated from site S7 (Shahdara drain intermixing zone). Correlation analysis between mean MIC site-wise results with mean heavy metal site-wise concentrations showed significant positive correlation indicating that the higher the mean concentration of a given heavy metal at a given site, the higher the mean MIC value for the strains isolated from the same site indicating higher level of resistance. Overall, the present study has shown that the presence of heavy metals in River Yamuna caused due to indiscriminate discharge of various effluents from different kind of sources as well as due to insufficient treatment capacity of sewage treatment plants as well as common effluent treatment plants, has serious impacts on its bacterial microflora as it leads to the development of resistant strains.

We compared the values of the minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) values ​​of three antimicrobial agents for 72 bovine isolates ofPasteurella multocida, 80 swine isolates ofP. multocida, 80 bovine isolates ofEscherichia coli, 80 swine isolates ofE. coli, and 80 isolates ofStaphylococcus aureusfrom bovine mastitis. The ratio of MIC90​​/MPC90which limited mutant selection window (MSW) was ≤ 0.12/4 mg/l for enrofloxacin, 0.5/≥ 64 mg/l for florfenicol and 4/≥ 128 mg/l for tulathromycin in bovineP. multocidaisolates, ≤ 0.12/2 mg/l for enrofloxacin, 0.5/≥ 64 mg/l for florfenicol and 4/≥ 128 mg/l for tulathromycin in swineP. multocidaisolates, 1/16 mg/l for enrofloxacin, 8/≥ 64 mg/l for florfenicol and 8/≥ 128 mg/l for tulathromycin in bovineE. coliisolates, 0.5/16 mg/l for enrofloxacin, ≥ 64/≥ 64 mg/l for florfenicol and 8/≥ 128 mg/l for tulathromycin in swineE. coliisolates, and 0.25/16 mg/l for enrofloxacin, 4/≥ 64 mg/l for florfenicol and 4/≥ 128 mg/l for tulathromycin inS. aureusisolates. These findings indicate that the dosage of antimicrobial agents to achieve serum concentration equal to or higher than MPC could reduce selection of resistant bacterial subpopulation.

Activity-guided isolation and identification of anti-staphylococcal components from Senecio tenuifolius Burm. F. leaf extracts

In vitro susceptibilities were determined for a total of 159 clinical isolates and 12 reference strains of yeasts belonging to different Candida species including 94 Candida albicans strains, and further genera such as Cryptococcus, Trichosporon, Geotrichum and Saccharomyces. Minimum inhibitory concentration (MIC) values for fluconazole and itraconazole were assessed using a microdilution technique with the semisynthetic high resolution (HR) medium supplemented with glucose and asparagine but without sodium hydrogen carbonate (pH 7.0), according to a proposal of the working group 'Clinical Mycology' of the German Speaking Mycological Society. Fluconazole MIC values for C. albicans were between 0.125 and > or = 128 micrograms ml-1. Thus, the median of 1 microgram ml-1 showed that the overall fluconazole susceptibility was good. As expected, Candida krusei (seven strains) exhibited diminished in vitro susceptibility with MIC values for fluconazole of 8 to 128 micrograms ml-1 with a median of 64 micrograms ml-1. Some Candida kefyr strains seemed to be less susceptible against fluconazole which was indicated by a MIC90 of 64 micrograms ml-1. Surprisingly, no Candida glabrata isolate exhibited a MIC value greater than 16 micrograms ml-1. Other Candida species, Trichosporon cutaneum, Geotrichum candidum and Saccharomyces cerevisiae showed low MICs to fluconazole. In vitro susceptibility testing of itraconazole revealed that all Candida species except C. albicans, but also Trichosporon cutaneum, Geotrichum candidum, and Saccharomyces cerevisiae exhibited acceptable low MIC values against itraconazole (0.03-2 micrograms ml-1). Their MIC90 values for itraconazole were in the close range between 0.125 and 2 micrograms ml-1. MIC values between 0.125 and 2 micrograms ml-1 were obtained, even for C. krusei strains. On the other hand, the range of C. albicans MICs was between 0.0125 and > or = 16 micrograms ml-1 with MIC50 and MIC90 values of 0.125 and > or = 16 micrograms ml-1, respectively, indicating that a considerable number of yeast strains have high MICs. The comparative evaluation of different experimental conditions revealed that there exists a marked influence both of inoculum size and incubation time on the results of susceptibility testing. Therefore, for routine usage 10(2) CFU ml-1 and 18-24 h incubation time for this microdilution method with HR medium are recommended.

Short communication: In vitro antimicrobial susceptibility of Mycoplasma bovis isolates identified in milk from dairy cattle in Belgium, Germany, and Italy

Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has the capacity to develop resistance to all classes of antimicrobial compounds. However, very little is known regarding its susceptibility to biocides (antiseptics and disinfectants) and capacity to form biofilms, particularly for Malaysian isolates. To determine the susceptibility of A. baumannii isolates to commonly-used biocides, investigate their biofilm-forming capacities and the prevalence of biocide resistance and biofilm-associated genes. . The minimum inhibitory concentration (MIC) values of 100 A. baumannii hospital isolates from Terengganu, Malaysia, towards the biocides benzalkonium chloride (BZK), benzethonium chloride (BZT) and chlorhexidine digluconate (CLX), were determined by broth microdilution. The isolates were also examined for their ability to form biofilms in 96-well microplates. The prevalence of biocide resistance genes qacA, qacE and qacDE1 and the biofilm-associated genes bap and abaI were determined by polymerase chain reaction (PCR). Majority of the A. baumannii isolates (43%) showed higher MIC values (> 50 µg/mL) for CLX than for BZK (5% for MIC > 50 µg/mL) and BZT (9% for MIC > 50 µg/mL). The qacDE1 gene was predominant (63%) followed by qacE (28%) whereas no isolate was found harbouring qacA. All isolates were positive for the bap and abaI genes although the biofilm-forming capacity varied among the isolates. The Terengganu A. baumannii isolates showed higher prevalence of qacDE1 compared to qacE although no correlation was found with the biocides' MIC values. No correlation was also observed between the isolates' biofilm-forming capacity and the MIC values for the biocides.

Introduction: The frequency of prosthetic joint infections (PJIs) due to Cutibacterium acnes (formerly Propionibacterium acnes) is increasing, especially shoulder PJIs. The recommended antibiotic prophylaxis for hip and knee arthroplasties is beta-lactam antibiotics, predominantly cephalosporins. However, for example in Sweden, isoxazolyl-penicillin cloxacillin is used. No specific recommendations for shoulder arthroplasties are available. The aim of the present study was to determine the minimum inhibitory concentration (MIC) values for different antibiotics for C. acnes; and, more specifically, to compare the MIC values for benzylpenicillin and oxacillin.Materials and methods: Minimum inhibitory concentration (MIC) values for nine different antibiotic agents were obtained by gradient test (Etest) using strains of C. acnes (n= 57) isolated from PJIs from shoulders (n=31), hips (n=21), and knees (n=5).Results: All isolates had low MIC values for most of the tested antibiotic agents, and showed a wild type MIC distribution. The exception was clindamycin with 9% of the isolates displaying decreased susceptibility. The MIC values obtained for benzylpenicillin were significantly lower than the MIC values for isoxazolyl-penicillin (oxacillin).Conclusion: These in vitro results indicate that benzylpenicillin might be a more effective prophylactic treatment to prevent shoulder PJIs caused by C. acnes. However, further studies on the subject are needed, and the effectiveness of the prophylactic treatment should be evaluated using randomized controlled studies and/or register-based studies.

Ixora coccinea L. (Rubiaceae) has been used traditionally for a variety of ailments and also cultivated for ornamental purposes. The present study investigated antimicrobial activity of methanolic extracts of various parts of I. coccinea and determined the chemical groups of the active constituents. Antimicrobial activity was assessed using agar disc diffusion, microdilution and thin layer chromatography (TLC) bioautography assays. Methanolic extracts of leaf, flower and stem of I. coccinea displayed good antimicrobial activity, with inhibition zone in the range of 6.7 to 11.3 mm. minimum inhibitory concentration (MIC) values for all three extracts ranged from 0.78 to 3.125 mg/ml. Leaf and stem extracts of I. coccinea showed broad-spectrum antimicrobial activity. Of interest, stem extracts had MIC values against Staphylococcus aureus that were only 62.4 times less potent than the vancomycin. Likewise, leaf and stem extracts displayed good antimicrobial activity of 62.4 and 31.2 times, respectively lesser than gentamycin against Shigella flexneri. Minimum bactericidal/ bacteriostatic concentration (MBC) values for active extracts ranged from 0.78 to 6.25 mg/ml. TLC bioautography and phytochemical screening of the leaf and stem extracts showed that the antimicrobial activity of these extracts may be attributed to compounds belonging to terpenoid, flavonoid, coumarin, alkaloid and phenolic groups. Key words: Antimicrobial, Ixora coccinea, minimum inhibitory concentration, minimum bacteriostatic/bacteriocidal concentration, bioautography.