Comparison of Epsilometer test and agar dilution method in detecting the sensitivity of Helicobacter pylori to metronidazole / 北京大学学报(医学版)

OBJECTIVE@#Agar dilution method (ADM) was used as the golden standard to evaluate the consistency of Epsilometer test (E-test) in detecting the sensitivity of Helicobacter pylori (H. pylori) to metronidazole.@*METHODS@#From August 2018 to July 2020, patients with H. pylori infection treated for the first time in Peking University Third Hospital for gastroscopy due to dyspepsia were included in this study. Gastric mucosas were taken from the patients with H. pylori infection. H. pylori culture was performed. Both the ADM and E-test were applied to the antibiotic susceptibility of H. pylori to metro-nidazole, and the consistency and correlation between the two methods were validated.@*RESULTS@#In the study, 105 clinical isolates of H. pylori were successfully cultured, and the minimum inhibitory concentration ≥ 8 mg/L was defined as drug resistance. Both ADM and the E-test showed high resistance rates to metronidazole, 64.8% and 62.9%, respectively. Among them, 66 drug-resistant strains were detected by ADM and E-test, and 37 were sensitive strains, so the consistency rate was 98.1%. Two strains were evaluated as drug resistance by ADM, but sensitive by the E-test, with a very major error rate of 1.9%. There was zero strain sensitive according to ADM but assessed as resistant by the E-test, so the major error rate was 0%. Taking ADM as the gold standard, the sensitivity of E-test in the detection of metronidazole susceptibility was 97.1% (95%CI: 0.888-0.995), and the specificity was 100% (95%CI: 0.883-1.000). Cohen's kappa analysis showed substantial agreement, and kappa coefficient was 0.959 (95%CI: 0.902-1.016, P < 0.001). Spearmans correlation analysis confirmed this correlation was significant (r=0.807, P < 0.001). The consistency evaluation of Bland-Altman method indicated that it was good, and there was no measured value outside the consistency interval. In this study, cost analysis, including materials and labor, showed a 32.2% higher cost per analyte for ADM as compared with the E-test (356.6 yuan vs. 269.8 yuan).@*CONCLUSION@#The susceptibility test of H. pylori to metronidazole by E-test presents better agreement with ADM. Because it is less expensive, less labor intensive, and more rapid, it is an easy and reliable method for H. pylori susceptibility testing.

Evaluation of rapid identification methods for foodborne diarrhea Campylobacter and detection of drug resistance / 中华检验医学杂志

Objective:To explore and evaluate a appropriate suitable method for detection of Campylobacter and antibiotic sensitivity test for foodborne diarrhea in clinical laboratories. Methods:Pre-experiment:a total number of 400 fecal samples of patients with foodborne diarrhea were prospectively collected from the intestinal disease clinic of Beijing Tongren Hospital from September 2017 to January 2018. Double-hole filtration culture method and modified cefoperazone charcoal deoxycholate (CCD) agar culture method were used for fecal culture in micro-aerobic environment for 48 hours, and then suspicious colonies were identified by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Meanwhile, C. jejuni and C. coli were detected by real-time quantitative polymerase chain reaction(qPCR). Large sample verification: 2 062 fecal samples of patients with foodborne diarrhea in three hospitals of different levels in different areas of Beijing were collected for qPCR detection and culture from April 2018 to March 2019. The antimicrobial sensitivity test (AST) of C. jejuni and C. coli was performed according to the disk diffusion method and agar dilution method recommended by Clinical and Laboratory Standards Institute and National Antimicrobial Resistance Monitoring System for Enteric Bacteria. The results of the three detection methods and the consistency of the two antibiotic sensitivity tests were compared. Results:In the pre-experiment, the positive rates of Campylobacter ( jejuni/coli) detected of qPCR, double-hole filtration culture and modified CCD agar culture were 9.0% (36/400), 5.0% (20/400)and 3.5% (14/400), and the difference was statistically significant ( P<0.01). The samples with negative result of qPCR were negative by both culture methods. The total positive rates of Campylobacter detected by qPCR was 8.1% (168/ 2 062)including 7.0% (144/2 062) for C. jejuni and 1.2% (24/2 062) for C. coli. The samples with positive qPCR results were cultured by double-hole filtration culture method and the positive rate was 61.9%(104/168), among which, the positive rate of C. jejuni and C. coli were 58.3%(84/144) and 83.3%(20/24) respectively, which was not significantly different from the detection rate and culture positive rate in the pre-test ( P>0.1). The resistance rates of C. jejuni and C. coli to ciprofloxacin were 94.0%(94/100) and 100.0%(24/24) and to erythromycin were 6.0%(6/100) and 33.3%(8/24). The results from two antibiotic sensitivity test methods were consistent (Kappa>0.75). Conclusions:qPCR is rapid, sensitive and easy to operate, so it is suitable for routine development in clinical laboratories. The double-hole filtration culture method is beneficial to the acquisition of strains and is essential for the further study of Campylobacter. There was no significant difference between agar dilution method and disk diffusion method in antibiotic sensitivity test. Campylobacter showed a very high resistance rate to quinolones, which was no longer suitable for the treatment of Campylobacter foodborne diarrhea in Beijing area. Macrocyclic lipid antibiotics should be preferred.

Qualitative anti-tubercular activity of synthetic ethyl 7-acetyl2-substituted-3-(4-substituted benzoyl) indolizine-1-carboxylate analogues

Both the emergence of multidrug-resistant and extensively drug-resistant tuberculosis (TB) are currently the majorchallenges in the treatment of TB. Only delamanid and bedaquiline have been recently approved as anti-TB drugs inthe past 40 years. In an attempt to search for active anti-TB compounds against the sensitive strain of Mycobacteriumtuberculosis, H37Rv—a series of synthetic ethyl 7-acetyl-2-substituted-3-(4-substituted benzoyl)indolizine-1-carboxylates (2a–r)—have been screened for in vitro qualitative anti-TB activity using an agar dilution method. Itwas found that compounds 2a, 2b, 2c, 2f, 2g, 2i, 2j, 2l, 2o, 2p, and 2r, which have various functional groups on theindolizine nucleus, were active against the H37Rv strain.

Phytochemical screening and in vitro evaluation of antioxidant and antimicrobial activities of Kedrostis africana (L.) Cogn

Objective To investigate phytochemical, antioxidant and antimicrobial activities of Kedrostis africana (K. africana). Methods Dried tubers of K. africana were extracted in acetone, water and ethanol. The total phenol, flavonoid, proanthocyanidin and tannin contents were determined spectrometrically. The antioxidant activity was examined using 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt, nitric oxide and hydrogen peroxide assays. The antimicrobial activity was determined by agar dilution method using minimum inhibitory concentration against 3 g positive and three gram negative strains while four fungal strains were also investigated. Results Total phenol, flavonoids, proanthocyanidin and tannin contents ranged from (5.32 ± 0.01) to (10.51 ± 0.01) mg GAE/g; (42.58 ± 0.02) to (529.23 ± 0.01) mg QE/g; (15.05 ± 0.00) to (585.64 ± 0.00) mg CE/g and (0.301 ± 0.010) to (0.937 ± 0.000) mg TAE/g, respectively. The IC

Antibiotic resistance and molecular epidemiology characteristics of methicillin-resistant Staphylococcus aureus in Shenzhen area / 中国人兽共患病学报

The aim of this study is to investigate antibiotic resistance and molecular epidemiology characteristics of methicillin-resistant Staphylococcus aureus (MRSA) in Shenzhen area.We collected 428 Staphylococcus aureus isolates from eight hospitals in Shenzhen in 2012.According to the results of minimum inhibitory concentration (MIC) to cefoxitin,26.2％ of Staphylococcus aureus isolates (112/428) were identified as MRSA.The MIC of 10 antimicrobial agents was determined by agar dilution method.Panton-Valentine leucocidin(PVL) was detected by polymerase chain reaction(PCR).Positive strains of PVL were detected by multilocus sequence typing(MLST).Among the 112 strains,the resistance rates to trimethoprim-sulfamethoxazole,moxifloxacin,ciprofloxacin,gentamicin,erythromycin,clindamycin and tetracycline were 4.46％,12.50％,16.96％,19.64％,46.42％,25.00％ and 26.79％ respectively.No isolates resistant to vancomycin,linezolid and teicoplanin were found.Among the 112 strains,there were 13 (11.61％) strains carried PVL gene.There were no significant differences in the resistance rates of PVL positive strains and negative strains to 10 kinds of antimicrobial agents.Among the 13 strains carried PVL gene,7 kinds of old sequences and 1 kind of new sequence type were found by MLST.ST338 and ST25 were the most common type.All the data indicate that surveillance of MRSA in Shenzhen has a distinct genetic background from other regions.

Phytochemical screening and in vitro evaluation of antioxidant and antimicrobial activities of Kedrostis africana(L.)Cogn

Objective: To investigate phytochemical, antioxidant and antimicrobial activities of Kedrostis africana(K.africana). Methods: Dried tubers of K.africana were extracted in acetone,water and ethanol.The total phenol, flavonoid, proanthocyanidin and tannin contents were determined spectro-metrically. The antioxidant activity was examined using 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt, nitric oxide and hydrogen peroxide assays.The antimicrobial activity was determined by agar dilution method using minimum inhibitory concentration against 3 g positive and three gram negative strains while four fungal strains were also investigated. Results: Total phenol, flavonoids, proanthocyanidin and tannin contents ranged from (5.32 ± 0.01) to (10.51 ± 0.01) mg GAE/g; (42.58 ± 0.02) to (529.23 ± 0.01) mg QE/g;(15.05 ± 0.00) to (585.64 ± 0.00)mg CE/g and (0.301 ± 0.010) to (0.937 ± 0.000)mg TAE/g, respectively. The IC50values of the ethanol extract for 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulphonic acid)and hydrogen peroxide were 0.054 and 0.057 mg/mL, respectively,aqueous extract had an IC50value of 0.135 7 mg/mL for nitric oxide while the acetone extract had an IC50value of 0.300 mg/mL for 2,2-diphenyl-1-picrylhydrazyl. The ethanol extract demonstrated effective antimicrobial activity against the tested pathogenic species with minimum inhibitory concentrations values ranging from 2.5–5.0 mg/mL for bacteria and(0.312 5–5.000 0)mg/mL for fungi, respectively. Conclusions: The tuber of K. africana showed potent free radical scavenging property and antimicrobial activity.

Antimicrobial susceptibility of Brazilian Clostridium difficile strains determined by agar dilution and disk diffusion

Abstract Clostridium difficile is a leading cause of diarrhea in hospitalized patients worldwide. While metronidazole and vancomycin are the most prescribed antibiotics for the treatment of this infection, teicoplanin, tigecycline and nitazoxanide are alternatives drugs. Knowledge on the antibiotic susceptibility profiles is a basic step to differentiate recurrence from treatment failure due to antimicrobial resistance. Because C. difficile antimicrobial susceptibility is largely unknown in Brazil, we aimed to determine the profile of C. difficile strains cultivated from stool samples of inpatients with diarrhea and a positive toxin A/B test using both agar dilution and disk diffusion methods. All 50 strains tested were sensitive to metronidazole according to CLSI and EUCAST breakpoints with an MIC90 value of 2 μg/mL. Nitazoxanide and tigecycline were highly active in vitro against these strains with an MIC90 value of 0.125 μg/mL for both antimicrobials. The MIC90 were 4 μg/mL and 2 μg/mL for vancomycin and teicoplanin, respectively. A resistance rate of 8% was observed for moxifloxacin. Disk diffusion can be used as an alternative to screen for moxifloxacin resistance, nitazoxanide, tigecycline and metronidazole susceptibility, but it cannot be used for testing glycopeptides. Our results suggest that C. difficile strains from São Paulo city, Brazil, are susceptible to metronidazole and have low MIC90 values for most of the current therapeutic options available in Brazil.

Antimicrobial activities of traditional Chinese medicine aqueous extract on propionibacterium acnes in vitro / 中华医学美学美容杂志

Objective To observe the effects of 19 kinds of traditional Chinese medicine (TCM) aqueous extracts in vitro on the standard and clinical strains of propionibacterium acnes.Methods We collected lesion contents of acne vulgaris patients and conducted anaerobic cultivation of propionibacterium acnes at 35 ℃ for forty-eight hours.After tested by oxygen resistance experiment,Gram staining microscopy,catalytic test,nitrate test and sugar fermentation experiment,ANI anaerobic identification card,and VITEK fully-automatic microbe instrument,the strains were identified as propionibacterium acnes.We used AGAR dilution method to test the MIC values of various TCM aqueous extracts.Results The MIC values of Cortex phellodendri,Scutellaria baicalensis,and Rhiubarb were 25 mg/ml,respectively;the MIC values of Sophora flavescens and Honeysuckle were 50 mg/ml;the MIC values of Forsythia was 100 mg/ml.13 kinds of TCM aqueous extract did not produce bacteriostasis at the highest concentration of 200 mg/ml including Belvedere fruit,Chinese bulbul,Hedyotis diffusa,Houttuynia cordata,Purslane,Yerbadetajo herb,Radix isatidis,Lithospermum erythrorhizon,Folium isatidis,Taraxacum,Semen plantaginis,Angelica dahurica,and Fructus cnidii.Conclusions Aqueous extracts of Cortex phellodendri,Scutellaria baicalensis,Rhubarb,Sophora flavescens,Honeysuckle and Forsythia have good inhibitory effects in vitro on Propionibacterium acnes.

In vitro antibacterial test of Chinese medicine compound preparation for common pathogenic bacteria in upper respiratory tract infection / 天津医药

Objective To observe the antimicrobial effect of a kind of Chinese medicine Qingre compound preparation on the common pathogenic bacteria of upper respiratory tract infection (URTI). Methods A total of 163 common pathogen?ic bacteria of URTI was selected in this study, including 74 non extended-spectrum β- lactamases (ESBLs)-producing Gram-negative bacteria (33 Escherichia coli, 24 Klebsiella pneumonia and 17 Pseudomonas aeruginosa), 10 ESBLs-produc?ing Gram-negative bacteria (6 Escherichia coli and 4 Klebsiella pneumoniae) and 79 Gram-positive bacteria [11 methicil?lin-resistant Staphylococcus aureus (MRSA), 46 methicillin-sensitive Staphylococcus aureus and 22 Streptococcus pneu?moniae]. Agar dilution method was adopted to perform the quantitative drug sensibility test. Agar plates that contained differ?ent concentrations of Qingre compound preparation were prepared. The bacterial suspension was planted on the plates. Then we observed the plates after incubation, and recorded the minimum inhibitory concentration (MIC). Results The antimicro?bial rates of Qingre compound preparation were 88, 176 and 22 g/L for MIC90 of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The antimicrobial effects of Qingre compound preparation were coincident on the MIC 90 of ES?BLs-producing strains and non ESBLs-producing strains. The accumulated antibacterial rates of different concentrations of medicine to Pseudomonas aeruginosa were the highest. The MIC90 values of Qingre compound preparation were 11, 11 and 22 g/L for MSSA, MRSA and Streptococcus pneumoniae. The MIC90 of MRSA was coincident with MSSA, but MIC50 of MRSA was slightly higher than that of MSSA. The accumulated antibacterial rates of different concentrations of medi cine to MSSA and MRSA were all higher than those of Streptococcus pneumonia. The accumulated antibacterial rate of MSSA was similar with that of MRSA. Conclusion The Chinese medicine Qingre compound preparation could restrain common patho?genic bacteria of URTI except Klebsiella pneumoniae. The antibacterial effect of Qingre compound preparation is significant?ly better in Ggram-positive bacteria than that of Gram-negative bacteria.

Establishing Quality Control Ranges for Antimicrobial Susceptibility Testing of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus: A Cornerstone to Develop Reference Strains for Korean Clinical Microbiology Laboratories

Quality control (QC) processes are being performed in the majority of clinical microbiology laboratories to ensure the performance of microbial identification and antimicrobial susceptibility testing by using ATCC strains. To obtain these ATCC strains, some inconveniences are encountered concerning the purchase cost of the strains and the shipping time required. This study was focused on constructing a database of reference strains for QC processes using domestic bacterial strains, concentrating primarily on antimicrobial susceptibility testing. Three strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) that showed legible results in preliminary testing were selected. The minimal inhibitory concentrations (MICs) and zone diameters (ZDs) of eight antimicrobials for each strain were determined according to the CLSI M23. All resulting MIC and ZD ranges included at least 95% of the data. The ZD QC ranges obtained by using the CLSI method were less than 12 mm, and the MIC QC ranges extended no more than five dilutions. This study is a preliminary attempt to construct a bank of Korean QC strains. With further studies, a positive outcome toward cost and time reduction can be anticipated.

Evaluation of the capability of four tests for identification of the in vitro susceptibility of tigecycline against Acinetobacter and Enterobacteriaceae isolates / 中华微生物学和免疫学杂志

Objective To evaluate the capability of four tests for identification of the in vitro suscepti-bility of tigecycline against Acinetobacter and Enterobacteriaceae isolates.Methods Disk diffusion test was per-formed to detect the sensitivity of 158 Acinetobacter and 339 Enterobacteriaceae isolates to tigecycline.The mini-mum inhibitory concentrations ( MICs) of tigecycline for non-sensitive isolates were detected by using broth dilu-tion method ( BDM) , MIC Test Strip ( MTS) and agar dilution method.The differences with antimicrobial sus-ceptibility among the four different methods were evaluated.Results Tigecycline showed good antibacterial ac-tivity against both non-sensitive Acinetobacter and Enterobacteriaceae isolates with most of the MIC50 values in the sensitivity range of (0.5-2) mg/L and all of the MIC90 values of 4 mg/L.The MIC50 and MIC90 values measured by BDM were respectively 1 mg/L and 4 mg/L.The sensitivity rates presented by the results of BDM were re-spectively 87.1%and 70.2%based on the standards made by Food and Drug Administration (FDA) and Euro-pean Committee on Antimicrobial Susceptibility Testing ( EUCAST) .Agar dilution method indicated that most of the MICs of tigecycline to Acinetobacter and Enterobacteriaceae isolates were two dilutions higher than those de-tected by BDM with essential agreement (EA) rate of 56.5%.Both the very major error (VME) and the major error (ME) values were 0 and the categorical agreement (CA) rate was 46.8%according to the FDA standard.The VME and CA values were 0.8% and 24.2% based on EUCAST standard.Compared with agar dilution method, MTS showed better results in determining the susceptibility of Acinetobacter and Enterobacteriaceae iso-lates to tigecycline with MIC50 and MIC90 values of 1.5 mg/L and 4 mg/L, which was similar to the capability of BDM.Referring to the FDA and EUCAST standards, the sensitivity rates were 83.1% and 21.0%, the CA rates was 81.5%and 29.8%, and the EA rate was 71.8%.Most of the results tested by MTS were one dilution higher than those by BDM.FDA standard showed better correlation than EUCAST standard.Disk diffusion method showed the ME, mE, VME and CA values were respectively 19.4%, 71.8%, 0 and 8.9%according to FDA standard.Conclusion Disk diffusion method, MTS and agar dilution method all showed differences with BDM in susceptibility testing.The capability of MTS was similar to that of BDM.The results evaluated by FDA standard were better than those by EUCAST standard.The in vitro susceptibility of bacteria to tigecycline could be tested by disk diffusion method using FDA standard for evaluation, and confirmed with MTS if isolates were resistance or intermediate strains.The BDM could be performed for further confirmation if necessary.

Reliability of Kirby-Bauer disk diffusion method for detecting meropenem resistance among non-fermenting gram-negative bacilli.

Background: Meropenem is empirically used as a last resort for the treatment of infections by non-fermenting gram-negative bacilli (NFGNB). Minimum inhibitory concentration (MIC) determined using agar or broth dilution methods is widely used for testing meropenem resistance. However, it is not possible in resource-poor settings. Aim: A prospective study was performed to evaluate the reliability of Kirby-Bauer disk diffusion (KBDD) method for detecting meropenem resistance among NFGNB. Materials and Methods: A total of 146 NFGNB consisting of 56 Acinetobacter baumannii, 24 Acinetobacter lwoffii, 48 Pseudomonas aeruginosa and 18 Pseudomonas spp. were included in the study. All the isolates were tested simultaneously by both KBDD method and agar dilution method. Results: Very major errors were not observed with A. baumannii, A. lwoffii and P. aeruginosa, while other Pseudomonas spp. showed a very major error rate of about 5.6%. The major error rates observed with A. baumannii, A. lwoffii, P. aeruginosa and Pseudomonas spp. were 1.8%, 0%, 2.1% and 28.6%, respectively. All the isolates showed a good correlation between zone diameters (KBDD method) and MICs (agar dilution method). The sensitivity and specificity of KBDD method for detecting meropenem resistance was above 90% for all the NFGNB except Pseudomonas spp. Conclusions: The KBDD method can be reliably used for routine testing of meropenem resistance in A. baumannii, A. lwoffii and P. aeruginosa. However, further studies are needed before employing this technique for detecting meropenem resistance in Pseudomonas spp.

Comparison of broth microdilution and agar dilution methods for antifungal susceptibility testing of Malassezia speciesin vitro / 中华皮肤科杂志

Objective To compare broth microdilution and agar dilution methods for in vitro testing of activities of fluconazole,ketoconazole and itraconazole against clinical Malassezia isolates.Methods Broth microdilution and agar dilution methods were used to determine the minimal inhibitory concentration(MIC)of fluconazole,ketoconazole and itraconazole for 27 clinical strains(5 species)of Malassezia.Results The minimal inhibitory concentration(MIC)ranges of fluconazole,ketoconazole and itraconazole were 0.25-≥64 mg/L,≤0.03-0.5 mg/L and ≤0.03-0.125 mg/L respectively as shown by broth microdilution method,2-≥64 mg/L,≤0.03-0.5 mg/L and ≤0.03-0.25 mg/L respectively as revealed by agar dilution method.Both methods demonstrated that itraconazole possessed the strongest activity against Malassezia species,followed by ketoconazole and fluconazole.The agreement rate in MICs between the two methods was 78.8％,85.2％ and 88.9％,respectively for fluconazole,ketoconazole and itraconazole,with the intraclass correlation coefficients (ICCs)being 0.88,0.80 and 0.76 respectively.Conclusions Fluconazole,ketoconazole and itraconazole are highly active against Malassezia species in vitro,and itraconazole is the most active.Broth microdilution and agar dilution method coincide well in,and are applicable for,the antifungal susceptibility testing of Malassezia species in vitro.

Bacterial contaminants of salad vegetables in Abuja Municipal Area Council, Nigeria

Salad vegetables are essential part of people’s diet all around the world. They are usually consumed raw and often without heat treatment or thorough washing; hence have been known to serve as vehicles for the transmission of pathogenic microorganism associated with human diseases. Fresh samples of lettuce, carrot and cucumber collected from different markets and vendors in Abuja Municipal Area Council, Federal Capital Territory, Nigeria were evaluated for bacterial loads using spread plate agar dilution method. Bacterial loads ranged from 1.6 x 106 to 2.9 x 108 cfu/g. Escherichia coli, Klebsiella and Enterobacter were amongst the coliforms (lactose fermenters), while Proteus, Pseudomonas aeruginosa, Salmonella and Shigella were non-lactose fermenters associated with the samples. Staphylococcus aureus was isolated from majority of the samples.

Pruebas de sensibilidad frente a agentes anti microbianos en cepas de Brachyspira pilosicoli aisladas a partir de ponedoras comerciales en Colombia / Antimicrobial susceptibility test in Brachyspira pilosicoli strains isolated from commercial layers farms in Colombia

Las espiroquetas intestinales del género Brachyspira ocasionan enfermedades importantes en porcinos y aves. Se ha evidenciado un problema de incremento en la presentación de cepas resistentes a los antimicrobianos utilizados normalmente para tratar las espiroquetosis intestinales en porcinos, y esto podría ser aplicable a los aislamientos de aves. Hay muypocos reportes de sensibilidad antimicrobiana in vitro de cepas de Brachyspira spp. aisladas en aves. En este estudio se evaluó la sensibilidad de doce aislamientos de Brachyspira pilosicoli obtenidos de granjas de ponedoras comerciales a los agentes antimicrobianos tiamulina, tilosina y lincomicina, y se estableció la concentración mínima inhibitoria (CMI)mediante la técnica de dilución en agar. Todas las bacterias analizadas fueron sensibles a tiamulina (CMI≤0,1 μg/ml) y lincomicina (CMI 1 μg/ml) y resistentes a tilosina (CMI 5 μg/ml).

Intestinal Spirochaetes of the genus Brachyspira cause important diseases in swine and poultry. An increasing problem in the presentation of resistant strains to the antimicrobial drugs usually used to treat the intestinal spirochaetosis in swine has been evidenced and this could be applicable to the isolations from poultry. There are very few reports of in vitro antimicrobialsusceptibility of Brachyspira spp. isolated from birds. In this study the antimicrobial susceptibility of twelve Brachyspira pilosicoli isolates obtain from commercial layers was evaluated against tiamulin, tylosin and lincomycin establishing the Minimum Inhibitory Concentration (MIC) by agar dilution technique. All bacteria analyzed were sensitive to tiamulin (MIC ≤0,1μg/ml), and lincomycin (MIC 1μg/ml) and resistant to tylosin (MIC 5μg/ml).

Comparación de las pruebas de dilución en Agar y PCR para determinación de susceptibilidad antimicrobiana de Helicobacter pylori. Revisión sistemática de la literatura / Comparation of Agar dilution test with Polymerase Chain Reaction (PCR) to determinate antimicrobial susceptiblility of Helicobacter Pylori. A systematic literature review

Objetivo: determinar las características operativas de la prueba RFLP-PCR frente a la prueba dilución en agar para evaluar la susceptibilidad antimicrobiana a claritromicina en aislamientos clínicos de H. pylori. Metodología: la búsqueda de estudios de pruebas diagnósticas sobre resistencia antimicrobiana de H. pylori a claritromicina con técnicas de dilución en agar y RFLP-PCR se realizó en Medline, Science direct, Ovid y Cochrane. Se elaboraron tablas de contingencia para calcular las características operativas, en el programa RevMan 5. La heterogeneidad fue evaluada por la gráfica Forest Plot y el estadístico de Q. La presencia de sesgos de publicación se evaluó con Funnel Plot. Resultados: doce artículos cumplieron con los criterios de inclusión. El overall de especificidad fue 100% (IC 95% 91-100), demostrando baja probabilidad de falsos positivos. Para sensibilidad el valor fue de 91% (IC 95% 88-94) indicando una mayor probabilidad de resultados falsamente negativos. En la gráfica de “Funnel Plot” se observó asimetría para ambas características demostrando sesgo de publicación. Conclusiones: la técnica RFLP-PCR no presentó características operativas iguales o superiores al 95%, comparada con el estándar de referencia dilución en agar. Por lo anterior esta técnica de se debe considerar la prueba de elección cuando se estudie la susceptibilidad antimicrobiana de H. pylori.

Aim: Establish the available scientific evidence of the operational characteristics of PCR-RFLP test with Agar Dilution for the determination of antimicrobial susceptibility in clarithromycin clinical isolates of Helicobacter pylori. Methods: We have performed the search bibliography about diagnostic tests on antimicrobial resistance of H. pylori to clarithromycin by using Agar Dilution and PCR-RFLP techniques over Medline, Science direct, Ovid and Cochrane of studies. The information was validated by two observers who checked the inclusion criteria and quality. We obtained the operational characteristics of the studies on contingency tables; analysis was performed on the RevMan 5 program. Results: A total of 50 references were tested from those 12 has been chosen in accord with the inclusion criteria and analyzed as summary measures. The specificity “overall” was a 100 % (CI 95% 91-100) that demonstrate a low probability of positive false. The projected overall sensitivity was 91% (CI 95% 88-94%) which indicated a high probability of negative results. The test showed heterogeneity studies homogeneous in sensitivity and specificity (p = 0.78) (p = 0.99). The graphics of “Funnel Plot” revealed asymmetry for both of those characteristics that showed a publications bias. In the group analysis have not found antibiotics different from clarithromycin and was evident that the continent was more publications Europe, followed by Asia and Latin America. Conclusion: The sensitivity and specificity of PCR-RFLP technique for clarithromycin not have values equal to or higher than 95% compared proof Agar Dilution.

Comparison of in vitro activity of five antifungal agents against dermatophytes, using the agar dilution and broth microdilution methods / Comparação da atividade in vitro de cinco agentes antifúngicos para dermatófitos, usando os métodos de diluição em ágar e microdiluição em caldo

The purpose of this study was to compare the agar dilution and broth microdilution methods for determining the minimum inhibitory concentration (MIC) of fluconazole, itraconazole, ketoconazole, griseofulvin and terbinafine for 60 dermatophyte samples belonging to the species Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. The percentage agreement between the two methods, for all the isolates with < 2 dilutions that were tested was 91.6 percent for ketoconazole and griseofulvin, 88.3 percent for itraconazole, 81.6 percent for terbinafine and 73.3 percent for fluconazole. One hundred percent agreement was obtained for Trichophyton mentagrophytes isolates evaluated with ketoconazole and griseofulvin. Thus, until a reference method for testing the in vitro susceptibility of dermatophytes is standardized, the similarity of the results between the two methods means that the agar dilution method may be useful for susceptibility testing on these filamentous fungi.

O propósito do presente trabalho foi comparar os métodos de diluição em ágar e diluição em caldo para a determinação de concentração inibitória mínima de fluconazol, itraconazol, cetoconazol, griseofulvina e terbinafina para 60 amostras de dermatófitos pertencentes às espécies, Trichophyton rubrum, Trichophyton. mentagrophytes e Microsporum canis. A porcentagem de acordo entre os dois métodos para todos os isolados testados considerando-se valores < 2 diluições, foram de 91,6 por cento para cetoconazol e para griseofulvina, de 88,3 por cento para itraconazol, de 81,6 por cento para terbinafina e de 73,3 por cento para fluconazol. Uma concordância de 100 por cento foi obtido para isolados de Trichophyton mentagrophytes avaliados com cetoconazol e griseofulvina. Desta forma, até que um método de referência seja padronizado para testar a suscetibilidade in vitro para os dermatófitos, os resultados semelhantes encontrados para os dois métodos fazem com que o método de diluição em ágar possa ser útil no teste de suscetibilidade para estes fungos filamentosos.

Clarithromycin and Amoxicillin Susceptibility Testing of Helicobacter pylori by Disk Diffusion Method / 대한임상미생물학회지

BACKGROUND: CLSI provides a guideline only for a agar dilution method of testing clarithromycin susceptibility for Helicobacter pylori. This study was to evaluate a disk diffusion method for clarithromycin and amoxicillin. METHODS: One hundred and forty clinical isolates of H. pylori isolated from May 2005 to May 2007 were tested by the CLSI agar dilution method and a disk diffusion method using 2microgram (2CLR) and 15microgram (15CLR) clarithromycin disks and 2microgram (2AMX) and 10microgram (10AMX) amoxicillin disks. The interpretation criteria used for the disk diffusion method were established by linear regression and error rate-bounded method for disk diffusion zone of inhibition (DDZ) compared to MIC. RESULTS: Resistance and intermediate rates to clarithromycin were 21.4% and 1.4%, respectively. A number of isolates with MIC 0.5, 1, and 2 (microgram/mL) to amoxicillin were 7, 2, and 1, respectively. For 2CLR and 15CLR, the coefficients of determination (R2) between MIC and DDZ were 0.931 and 0.923 (P< 0.001), respectively, and the criteria for resistance/ susceptibility were 12/28 mm for 2CLR and 23/39 mm for 15CLR. For 2AMX and 10AMX, the R2 between MIC and DDZ were 0.478 and 0.421 (P< 0.001), respectively, and the criteria for resistance with breakpoint of 2microgram/mL were 21 mm for 2AMX and 32 mm for 10AMX. All isolates had DDZ<60 mm with 2CLR and 2AMX, but 61.4% and 75.7% of the isolates had DDZ<60 mm with 15CLR and 10AMX, respectively. CONCLUSION: Excellent correlation and agreement between MIC and DDZ were found for clarithromycin and amoxicillin. With 2microgram disks, the susceptibility breakpoints were 28 mm or less; thus, two disks could be tested in one plate.

Comparison of antibacterial activities of different concentrations of the cefoperazone-sulbactam combination disc upon commonly found gram negative bacilli / 中华急诊医学杂志

Objective To evaluate antibacterial activities of Cefoperazone-Sulbactam upon gram negative bacilli,and compare the differences in susceptibility between two different concentrations of Cefoperazone-Sulbactam combination disc.Method A total of 381 strains of commonly occurred gram negative bacilli were found from 2nd Affiliated Hospital of Zhejiang University School of Medicine,Zhejiang Provincial People's Hospital,The Third Hospital of Hangzhou and Hangzhou Hospital of Traditional Chinese Medicine respectively.Susceptibility test was conducted by K-B method using 75 μg/disc Cefoperazone plus with 75 μg/disc Sulbactam(150 disc)and 75 μg/disc Cefoperazone with 30 μg/disc Sulbactam(105 disc),respectively.Meanwhile the minimal inhibitory concentration(MIC)of Cefoperazone-Sulbactam was determined by standard agar dilution.The data were analyzed by using WHONET 5.4 and SPSS.Results Disc diffusion method was carried out to detect the antibacterial activities upon Escherichia coli,Klebsiella pneumonia,Pseudomonas aeruginosa and Acinetobacter baumannii,using 105 disc and 150 disc,respectively.The data indicated that consistency rates between these two different discs were 26.3%,79.2%,83.7%and 33%,respectively.The k-related sample test was performed by using SPSS version 10.0 and shown that the P value was less than 0.05.Upon those organisms mentioned above,the consistency rates between the antibacterial activities of 105 disc and those of agar dilution were 77.8%,89.6%,70.9%and 77%,respectively.When it was going to compare agar dilution vs.150 disc upon the susceptibility of those organisms the consistency rates were 27.3%,79.2%,61.6%and 30%,respectively.Compared with agar dilution,the error rates of those two different concentration discs revealed that the false susceptibility and false intermediate of 105 disc were higher than those of 105 disc.ConclusionsThe results of susceptibility test showed that 105 disc was more close to agar dilution than that of 150 disc.However,the 150 disc used in clinic led to increase in sensitivity of susceptibility test to organisms.

Amplification of mecA Gene and Resistance Phenotype in the Evaluation of the Methods for Detection of Methicillin-resistant Strains of Staphylococci / 医学研究杂志

Objective In order to choose a suitable method in detecting MRS,the detection rate,sensitivity and specificity of Vitek-32 auto microbacteria indentity system,oxacillin agar dilution test,cefoxitin disk diffusion test and PCR for mecA gene are evaluated.Methods MRSA and MRCNS are detected by the four methods metioned above in 175 staphylococci,then comparing the postive detection rate by Chi-square test and calculating sensitivity and specificity of the other three methods based on PCR for meeA gene as a gold standard.Results The detection rate of four methods have no difference in detecting MRSA,but the detection rate of Vitek-32 auto microbacteria indentity system and oxacillin agar dilution test is better than that of PCR for mecA gene in detecting MRCNS.Sensitivity and specificity of Vitek-32 auto microbacteria indentity system,oxacillin agar dilution test and cefoxitin disk diffusion test in detecting MRSA are 100%、96.3%、96.3% and 88.2%、100%、100% respectively,the sensitivity of detecting MRCNS are all 100%,the specificity of detecting MRCNS are 50%、46.1% and 65.4% respectively.Conclusions Both mecA gene and the determination for MIC of Oxacillin should be considered in final decision for MRS,Furthermore.the MRS mediated by mecA gene and the MRS mediated by non-mecA gene should be treated differentially.