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We aimed to assess the accuracy of BD Phoenix for determining carbapenem susceptibility because we observed a decline in carbapenem susceptibility rate from the biannual cumulative data, after we transitioned to the BD Phoenix form Vitek 2 system. Between October 2021 and May 2022, we collected 82 non-duplicated Enterobacterales showing non-susceptible to at least one of the three carbapenems by BD Phoenix. We performed the broth microdilution (BMD) and disk diffusion (DD) according to the CLSI guideline. Compared to BMD, the categorical agreements for ertapenem (ERT), imipenem (IPM) and meropenem (MEPM) was 58.8%, 56.8% and 91.5% for BD Phoenix and it was 85.4%, 89.0%, and 97.6%, respectively, for DD (p value; 0.0001 for ERT and IPM, p value; 0.17 for MEPM). The major errors/minor errors for ERT, IPM, and MEPM were 14.0%/31.7%, 2.94%/40.7%, and 2.56%/6.10%, respectively for BD Phoenix, compared to 0%/14.6%, 0%/9.8%, and 0%/2.5%, for DD. While errors in the BD Phoenix showed tendency towards resistance, those in DD displayed no tendency towards either resistance or susceptibility. With DD, 21 out of the 27 isolates showing susceptible/intermediate/susceptible pattern (ERT/IPM/MEPM) and 13 out of the 16 isolates showing intermediate/susceptible/susceptible pattern (ERT/IPM/MEPM), were correctly categorized by DD. However, for 22 isolates showing resistant/susceptible/susceptible pattern (ERT/IPM/MEPM), only 13 isolates were correctly categorized by DD. In conclusion, to mitigate the risk of overcalling carbapenem non-susceptibility with BD Phoenix, it will be helpful to perform a complementary test using DD and to provide comments on the DD results to clinicians.
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OBJECTIVE: To compare the performance of agar dilution and broth microdilution by commercial and in-house prepared plates for the Bacteroides fragilis group. The cost analysis was performed to demonstrate that in-house prepared BMD plates were a suitable alternative to agar dilution given the high cost and low feasibility of incorporating commercial BMD plates in routine, particularly in the tertiary care institutes of many low- and middle-income countries. METHODS: Thirty B. fragilis group isolates were tested against six antibiotics, frequently used as empirical therapy for anaerobic infections including metronidazole, clindamycin, imipenem, piperacillin-tazobactam, cefoxitin, and chloramphenicol. The running consumable expenditure for all methodologies was calculated. RESULTS: The results demonstrated essential and categorical agreement of >90% for all antibiotics except cefoxitin, which showed <90% categorical agreement. No major or very major errors were observed. We observed a high agreement and strong concordance for MIC values between both methods and inter-rate reliability of >0.9 by Cohen's kappa analysis, indicating almost perfect agreement between both methods using either of the plates. In contrast to agar dilution, a 20.5 fold cost reduction was seen in BMD using in-house plates and a 5.8 fold reduction using commercial plates to test a single isolate. However, when testing 30 isolates concurrently the cost significantly increased for commercial BMD plates by 8.4 folds, and only 1.03 fold cost reduction was seen with in-house BMD plates. CONCLUSION: BMD gives comparable results to agar dilution and can be considered a method of choice to test a small number of samples. The technique is an economical option when plates are standardized in-house and could be employed for susceptibility testing of the B. fragilis group.
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Agar/economía , Antibacterianos/farmacología , Infecciones por Bacteroides/microbiología , Bacteroides fragilis/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/economía , Pruebas de Sensibilidad Microbiana/métodos , Agar/química , Antibacterianos/economía , Bacteroides fragilis/crecimiento & desarrollo , Clindamicina/economía , Clindamicina/farmacología , Humanos , Imipenem/economía , Imipenem/farmacología , Metronidazol/economía , Metronidazol/farmacología , Pruebas de Sensibilidad Microbiana/instrumentaciónRESUMEN
Susceptibility profiles of anaerobic bacteria to antibiotics have become unpredictable, thus reliable and user-friendly methods for routine susceptibility testing are needed. In this study, we evaluated the MICRONAUT-S Anaerobes MIC test plate, a commercially available broth microdilution method, and suitable for clinical microbiology routine testing. We analyzed a collection of 300 consecutive clinically significant isolates, including 149 Gram-positive and 151 Gram-negative strains. The performance of the MICRONAUT-S Anaerobes MIC plate was compared to that of a gradient diffusion method (current laboratory standard), calculating the essential and the categorial agreement. 99.7% (299/300) of the strains included in this study successfully grew in the MICRONAUT-S Anaerobes MIC plate (73% of them after 24 h of incubation), while 1 Porphyromonas uenoni isolate didn't grow. It showed a high concordance with the gradient diffusion method. Overall essential and categorical agreements resulted >95% and >97%, respectively, and only a low rate of errors was observed. Beyond the very good analytical performance, several technical advantages in comparison with the gradient diffusion method were observed, that contribute to make the MICRONAUT-S Anaerobes panels suitable for an easy implementation into laboratory routine.
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Pruebas de Sensibilidad Microbiana/métodos , Antibacterianos/farmacología , Bacterias Anaerobias/efectos de los fármacosRESUMEN
Vancomycin (VAN) minimum inhibitory concentrations (MICs) at the upper end of the susceptible range for Staphylococcus aureus (S. aureus), as measured by the Etest method, have been associated with poor clinical outcomes of S. aureus bloodstream infections, as has the isolate's genetic background. Here, we assessed the impact of VAN MICs, as determined by a broth microdilution method (BMD) that incorporates incremental VAN concentrations between the conventional log2 dilutions, isolate susceptibility to killing by human phagocytes, acting as a surrogate marker for bacterial cell wall thickness, and S. aureus genetic composition, on the development of complicated S. aureus bacteremia (SAB). We carried out a retrospective, observational single-center cohort study of 148 consecutive patients with SAB caused by methicillin-susceptible (MSSA) isolates (n = 113) or methicillin-resistant (MRSA) isolates (n = 35). S. aureus isolates were genotyped using a commercially available DNA microarray. Overall, VAN MICs of S. aureus isolates taken from complicated and uncomplicated SAB were comparable, irrespective of the testing method (P = 0.19 with BMD, and P = 0.94 with Etest). Likewise, S. aureus isolates in both comparison groups had the same susceptibility to killing by human phagocytes (P = 0.5). Among the genes screened by the S. aureus DNA array, only Sec and Sel were differentially present among S. aureus isolates in both groups (overrepresented in those causing complications) and their presence was associated independently with complicated SAB in multivariate models adjusted for potentially relevant clinical covariates. Separate analysis of MSSA SAB episodes yielded similar results.
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Antibacterianos/farmacología , Bacteriemia/microbiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/efectos de los fármacos , Vancomicina/farmacología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/uso terapéutico , Bacteriemia/tratamiento farmacológico , Bacteriemia/epidemiología , Niño , Preescolar , Estudios de Cohortes , Femenino , Genotipo , Glicopéptidos/farmacología , Glicopéptidos/uso terapéutico , Humanos , Lactante , Masculino , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Fagocitos/inmunología , Fagocitos/microbiología , Estudios Retrospectivos , Factores de Riesgo , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación , Vancomicina/uso terapéutico , Adulto JovenRESUMEN
In recent years, because of carbapenemase spreading in Klebsiella pneumoniae strains, the antibiotic of reserve group, colistin, is increasingly prescribed. In vitro testing of colistin susceptibility in everyday practice has a number of difficulties due to the cationic properties of molecule and weak diffusion into agar. Therefore it is recommended to use the reference Broth Microdilution Method (BMD) for determination of the Minimum Inhibitory Concentration (MIC) for colistin. The purpose of the study was to determine susceptibility to colistin in 119 carbapenem-resistant K. pneumoniae (CRKp) which were isolated from the patients at three hospitals in Moscow in 2012-2016 by the broth microdilution method (BMD) and to compare these data with the ones obtained by epsilometer test (E-test) and VITEK 2 Compact. The proportion of resistant isolates (MIC>2 mg/L) was 52%, 39%, 35% respectively. Both commercial methods demonstrated a high level of the very major error (VME) that was 26% for the E-test method and 34% for the VITEK 2 Compact. The values of categorical agreement and essential agreement (CA, EA) were less than 90%. A single major error (ME) was detected for the VITEK 2 Compact. In conclusion, results of both commercial tests for determination of MIC for colistin showed differences with the results of the reference BMD. It is necessary for clinical laboratories to be aware about this discrepancy and to use E-tests and VITEK 2 Compact with caution to determine colistin susceptibility.
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Klebsiella pneumoniae , Antibacterianos , Carbapenémicos , Colistina , Humanos , Pruebas de Sensibilidad MicrobianaRESUMEN
BACKGROUND: The management of Candida infections faces many problems, such as a limited number of antifungal drugs, toxicity, resistance of Candida to commonly antifungal drugs, relapse of Candida infections, and the high cost of antifungal drugs. Though azole antifungal agents and derivatives continue to dominate as drugs of choice against Candida infections, there are many available data referring to the anticandidal activity of essential oils. Since we have previous observed a good antimicrobial activity of some essential oils against filamentous fungi, the aim of this study was to extend the research to evaluate the activity of the same oils on Candida albicans, C.glabrata and C.tropicalis clinical strains, as well as the effects of related components. Essential oils selection was based both on ethnomedicinal use and on proved antibacterial and/or antifungal activity of some of these oils. Fluconazole and voriconazole were used as reference drugs. METHODS: The minimum inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) of essential oils (thyme red, fennel, clove, pine, sage, lemon balm, and lavender) and their major components were investigated by the broth microdilution method (BM) and the vapour contact assay (VC). RESULTS: Using BM, pine oil showed the best activity against all strains tested, though C.albicans was more susceptible than C.glabrata and C.tropicalis (MIC50-MIC90 = 0.06 %, v/v). On the contrary, sage oil displayed a weak activity (MIC50-MIC90 = 1 %, v/v). Thyme red oil (MIC50-MIC90 ≤ 0.0038 %, v/v for C.albicans and C.tropicalis, and 0.0078- < 0.015 %, v/v for C.glabrata), followed by lemon balm, lavender and sage were the most effective by VC. Carvacrol and thymol showed the highest activity, whereas linalyl acetate showed the lowest activity both by two methods. α-pinene displayed a better activity by BM than VC. CONCLUSION: Results show a good activity of essential oils, mainly thymus red and pine oils, and their components carvacrol, thymol and α-pinene against Candida spp., including fluconazole/voriconazole resistant strains. These data encourage adequately controlled and randomized clinical investigations. The use in vapour phase could have additional advantages without requiring direct contact, resulting in easy of environmental application such as in hospital, and/or in school.
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Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Candida/efectos de los fármacos , Aceites Volátiles/farmacología , Aceites de Plantas/farmacología , Antifúngicos/química , Pruebas de Sensibilidad Microbiana , Aceites Volátiles/química , Aceites de Plantas/química , Plantas Medicinales/químicaRESUMEN
The minimum inhibitory concentrations (MICs) of colistin for 241 multidrug-resistant (MDR) Gram-negative pathogens were determined by the Etest and by the broth microdilution method (BMD). The two methods showed essential agreements of 76% (77/102) for Acinetobacter baumannii, 90% (36/40) for Pseudomonas aeruginosa and 84% (83/99) for Enterobacteriaceae isolates, with categorical agreements of 100%, 98%, and 100%, respectively. Of the 241 isolates, none showed a very major error and one (0.4%) showed a major error. MICs ranged from 0.125 to 0.5 µg/ml for all A. baumannii and most Enterobacteriaceae isolates, and from 1 to 2 µg/ml for most P. aeruginosa isolates. Of the 40 P. aeruginosa isolates, 27 (68%) showed higher colistin MICs by the Etest than by the BMD. In contrast, 77% (78/102) of the A. baumannii and 57% (56/99) of the Enterobacteriaceae isolates showed lower colistin MICs by the Etest than by the BMD. The Etest is a reliable and easy-to-use method to measure colistin MICs of MDR Gram-negative pathogens in clinical laboratories and can be used following validation by microdilution methods.
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Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/farmacología , Colistina/farmacología , Enterobacteriaceae/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Pseudomonas aeruginosa/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Farmacorresistencia Bacteriana Múltiple , Enterobacteriaceae/aislamiento & purificación , Pseudomonas aeruginosa/aislamiento & purificación , VietnamRESUMEN
The anaerobic bacteria resistance to antibiotics is increasing, and even has appeared against the most active of those, like metronidazol and carbapenems. This fact forces to make and periodical sensibility tests -at least in the most aggressive and virulent species, in cases that they are isolated from life locations and in the absence of therapeutic response- to check the local sensibility and to establish suitable empiric therapies, all based on multicentric studies carried out in order to this or well to check the activity of new antibiotics. For the laboratory routine, the easiest sensibility method is the E-test/MIC evaluator. Another alternative is microdilution, that's only normalized for Bacteroides. There are preliminary facts that allow the use of disc diffusion method in some species of Bacteroides and Clostridium. For the temporal and multicentric studies, the procedure is dilution in agar plate, the reference method.
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Bacterias Anaerobias/efectos de los fármacos , Humanos , Pruebas de Sensibilidad Microbiana/métodosRESUMEN
This research paper reports an enhancement of thermal, optical, mechanical and antibacterial activities of the Polyvinyl alcohol-Nanodiamonds (PVA-NDs) composite required for the food packaging industry. The synthesis of composites was done by the wet processing method. The large surface area of NDs facilitated the robust interaction between the hydroxyl group and macromolecular chains of PVA to enhance the hydrogen bonding of PVA with NDs rather than PVA molecules. Thus, a reduction in PVA diffraction peak intensity was reported. NDs improved the thermal stability by preventing the out-diffusion of volatile decomposition products of PVA. The results also revealed an enhancement in tensile strength (â¼60 MPa) and ductility (â¼180 %). PVA-NDs composite efficiently blocked the UVC (100 %), most of the part of the UVB (â¼85 % above 300 nm), and UVA (â¼58 %). Furthermore, enhanced antibacterial activities were reported for PVA-NDs composite against E. coli and S. aureus. NDs accumulated around the bacterial cells prevented essential cellular functions and led to death. Hence, this composite could be a promising candidate for safe, thermally stable, strong, flexible, transparent, UV- resistant antibacterial food packaging material.
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Antimicrobial resistance (AMR) is a significant public health threat, with the food production chain, and, specifically, fermented products, as a potential vehicle for dissemination. However, information about dairy products, especially raw ewe milk cheeses, is limited. The present study analysed, for the first time, the occurrence of AMRs related to lactic acid bacteria (LAB) along a raw ewe milk cheese production chain for the most common antimicrobial agents used on farms (dihydrostreptomycin, benzylpenicillin, amoxicillin and polymyxin B). More than 200 LAB isolates were obtained and identified by Sanger sequencing (V1-V3 16S rRNA regions); these isolates included 8 LAB genera and 21 species. Significant differences in LAB composition were observed throughout the production chain (P ≤ 0.001), with Enterococcus (e.g., E. hirae and E. faecalis) and Bacillus (e.g., B. thuringiensis and B. cereus) predominating in ovine faeces and raw ewe milk, respectively, along with Lactococcus (L. lactis) in whey and fresh cheeses, while Lactobacillus and Lacticaseibacillus species (e.g., Lactobacillus sp. and L. paracasei) prevailed in ripened cheeses. Phenotypically, by broth microdilution, Lactococcus, Enterococcus and Bacillus species presented the greatest resistance rates (on average, 78.2 %, 56.8 % and 53.4 %, respectively), specifically against polymyxin B, and were more susceptible to dihydrostreptomycin. Conversely, Lacticaseibacillus and Lactobacillus were more susceptible to all antimicrobials tested (31.4 % and 39.1 %, respectively). Thus, resistance patterns and multidrug resistance were reduced along the production chain (P ≤ 0.05). Genotypically, through HT-qPCR, 31 antimicrobial resistance genes (ARGs) and 6 mobile genetic elements (MGEs) were detected, predominating Str, StrB and aadA-01, related to aminoglycoside resistance, and the transposons tnpA-02 and tnpA-01. In general, a significant reduction in ARGs and MGEs abundances was also observed throughout the production chain (P ≤ 0.001). The current findings indicate that LAB dynamics throughout the raw ewe milk cheese production chain facilitated a reduction in AMRs, which has not been reported to date.
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Antibacterianos , Queso , Farmacorresistencia Bacteriana , Lactobacillales , Leche , Animales , Queso/microbiología , Leche/microbiología , Ovinos , Lactobacillales/genética , Lactobacillales/efectos de los fármacos , Lactobacillales/aislamiento & purificación , Antibacterianos/farmacología , Farmacorresistencia Bacteriana/genética , Fenotipo , Microbiología de Alimentos , Genotipo , ARN Ribosómico 16S/genética , Pruebas de Sensibilidad Microbiana , Heces/microbiología , FemeninoRESUMEN
Non-saleable milk (waste milk, WM) is contaminated with an undefined spectrum of potentially harmful pathogens and antimicrobial residues. The objective of this study was to determine the impact of feeding bulk milk (BM) or WM - both pasteurized or not - on calf performance, health and the antibiotic resistance of specific faecal bacteria. A total of 114 calves from a large-scale dairy were housed outdoors in individual hutches and were randomly assigned to one of four feeding groups. The calves were fed either WM, pasteurized WM (pWM), BM or pasteurized BM (pBM) from day 3 to 56 of life. Milk samples taken from the pasteurizer and calves' nipple buckets were investigated at regular intervals for total plate count and counts of thermoduric bacteria, coliforms and mastitis pathogens. Faecal samples were taken on days 2, 14, 28 and 56 of life from randomly selected calves of the WM, pWM and BM groups (each N = 8-9) and processed to obtain from each sample preferably two isolates of Escherichia (E.) coli and Enterococcus spp. respectively. Isolates were tested for their antimicrobial susceptibility to 25 antimicrobial agents by broth microdilution. Daily weight gain, milk and calf starter intake and health parameters did not differ significantly between the calves of the four feeding groups. The proportion of resistant E. coli isolates was significantly higher in calves fed WM and in calves fed pWM (most pronounced for cephalosporins) than in calves receiving BM. No differences in resistance were found for Enterococus spp. Thus, the concerns for selecting resistant faecal bacteria by feeding WM seem to be justified. Nonetheless, pasteurized WM of cows not treated with antimicrobials represents an acceptable feed for young calves.
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Antibacterianos/farmacología , Enfermedades de los Bovinos/prevención & control , Bovinos/crecimiento & desarrollo , Heces/microbiología , Leche/metabolismo , Alimentación Animal/análisis , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Industria Lechera , Dieta/veterinaria , Farmacorresistencia Bacteriana , Femenino , Masculino , Leche/química , PasteurizaciónRESUMEN
Hebanthe eriantha is a medicinal plant used in folk medicine and a subject of commercial interest. The cytotoxicity effects from H. eriantha root extracts on cancerous and normal cells were assessed by the MTT method, and in vitro toxicity was evaluated on Artemia salina. The inhibition of the proliferation of bacteria and MIC values were examined by the disc diffusion and the broth microdilution method, respectively. Human colon cancer HCT116 and mouse breast tumour model 4T1 cells treated with methanolic extract showed a significant decrease in viability of cells with IC50: 272.6 and 88.5 µg/mL at 72h, respectively. The methanolic extract of H. eriantha showed moderate toxicity against A. salina (LC50: 589.4 µg/mL). In antimicrobial activity, the methanolic extract showed the highest inhibitory function against S. aureus and P. vulgaris (17.5 and 16 mm) with MICs of 500 µg/mL. The results confirmed the potential of plant roots as cytotoxic agents.
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DL96 Microbial Identification/Antimicrobial Susceptibility Testing (ID/AST) System (Zhuhai DL, Guangdong, China) is one of the most commonly used commercial ID/AST System in China. This study aims to evaluate the performance of DL 96E for Antimicrobial Susceptibility Testing (AST) of 270 Enterobacterales isolates from Hainan general hospital using the broth microdilution method (BMD) as reference method. CLSI M52 criteria was followed when analyzing the evaluation results. Twenty antimicrobial agents were evaluated, and categorical agreement (CA) ranged from 62.8% to 96.5%. Imipenem had the lowest CA (63.9%) and highest very major errors (VME) (52.8%). A total of 103 carbapenem-resistant Enterobacterales were evaluated; DL 96E miss identified 22 isolates, including six carbapenemase-producing Enterobacteriaceae. DL 96E must adjust the Minimum Inhibitory Concentration (MIC) ranges of ciprofloxacin, levofloxacin, and piperacillin-tazobactam to cover Clinical and Laboratory Standards Institute (CLSI) breakpoints, adjust the formulation of some antimicrobial, such as imipenem, and increase the MIC detection range to cover the Quality control (QC) strains' MIC range.
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So far there is no internationally accepted, standardized method for MIC determination of natural substances such as essential oils (EOs). The aim of this study was to elucidate how much the MIC values obtained from various studies using different culture media are comparable. The median MICs for cinnamon essential oil (EO) obtained by broth dilution were 517, 465 and 517 µg/mL for Mueller-Hinton Broth (MHB), Tryptone Soya Broth (TSB) and Brain Heart Infusion (BHI), respectively. The MIC values for oregano EO were significantly (p < 0.001) lower in MHB than in highly nutritious media; the median MICs were 616 µg/mL for MHB and 474 µg/mL for TSB and BHI. This statistically significant difference was noted for all the pathogens studied (Salmonella Enteritidis, Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus). In the presence of oregano EO lag phase was also much less prolonged in MHB (by 6-17%) than in the other media (by 92-189%). Some components of EOs may bind to starch in MHB; since the phenomenon seems to be selective and EO dependent, the use of MHB for comparison of antimicrobial properties of various EOs thus cannot be recommended.
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This study aimed to assess the comparability of in vitro susceptibility testing methods to ceftazidime-avibactam (CZA) and ceftolozane-tazobactam (C/T). Meropenem-resistant and/or carbapenemase-producing clinical isolates of Enterobacterales (Enterobacteriaceae) and Pseudomonas aeruginosa were tested by both bioMérieux ETEST and VITEK-2 AST-N397 card and compared with a Micronaut AST-system broth microdilution (BMD) method. CZA and C/T MICs were interpreted using EUCAST breakpoints. Of the 153 Enterobacteriaceae isolates, 55.6% and 0.0% (VITEK 2) and 56.9% and 0.0% (ETEST and BMD) were susceptible to CZA and C/T, respectively. Of 52 P. aeruginosa isolates, 50.0% and 40.4% (VITEK 2, ETEST, and BMD) were susceptible to CZA and C/T, respectively. The essential agreement (EA) was 96.1% (197/205; VITEK 2 versus BMD) and 95.6% (196/205; ETEST versus BMD) for CZA testing, whereas EA was 98.0% (201/205; VITEK 2 versus BMD) and 96.6% (198/205; ETEST versus BMD) for C/T testing. The categorical agreement (CA) was 98.0% (201/205; VITEK 2 versus BMD) and 100% (ETEST versus BMD) for CZA testing, whereas CA was 100% (VITEK 2 versus BMD) and 100% (ETEST versus BMD) for C/T testing. Categorical errors regarded four Enterobacteriaceae isolates. VITEK 2 and ETEST yielded equivalent CZA and C/T susceptibility testing results, compared to the BMD method, in such a clinical context.
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OBJECTIVES: Decreased susceptibility to ceftazidime/avibactam (CZA) and ceftaroline (CPT) has been reported during antimicrobial resistance surveillance and therapy. Conventional laboratories are unable to provide timely susceptibility testing for CZA and CPT because these antimicrobial agents are not incorporated in automated susceptibility testing systems. METHODS: We evaluated Etest and the Sensititre broth microdilution (BMD) method for testing CZA against carbapenem-resistant Gram-negative bacilli and CPT against important Gram-positive cocci bloodstream isolates. Genotypes of carbapenemases in Enterobacterales were also determined using the Xpert® Carba-R assay. RESULTS: Etest showed ≥90% agreement with Sensititre BMD for carbapenem-resistant Klebsiella pneumoniae (CRKP) (n = 187), carbapenem-resistant Escherichia coli (CREC) (n = 28) and Streptococcus pneumoniae (n = 35); however, the very major error rate exceeded 3%. Agreement between Etest and Sensititre BMD was <90% for carbapenem-resistant Pseudomonas aeruginosa (CRPA) (n = 81), methicillin-susceptible Staphylococcus aureus (MSSA) (n = 92) and methicillin-resistant S. aureus (MRSA) (n = 170). Both agents remained potent with a high susceptibility rate by Sensititre BMD as follows: CZA against CRKP (95.0%), CREC (89.3%) and CRPA (84.5%); and CPT against MSSA (100.0%), MRSA (95.3%) and S. pneumoniae (94.3%). CZA was active against blaKPC-carrying CRKP (98.5% susceptible), and resistance in the majority of CZA-resistant Enterobacterales isolates (6 of 10 CRKP and 2 of 3 CREC) was due to the presence of a metallo-ß-lactamase gene. CONCLUSION: Our results suggest that interpretation of susceptibility results obtained by Etest for both agents should be undertaken cautiously and remains challenging.
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Ceftazidima , Staphylococcus aureus Resistente a Meticilina , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Compuestos de Azabiciclo , Carbapenémicos , Ceftazidima/farmacología , Cefalosporinas , Pruebas Antimicrobianas de Difusión por Disco , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/genética , Staphylococcus aureus , Streptococcus pneumoniae , CeftarolinaRESUMEN
Medicinal plants are used to treat infectious and inflammatory diseases in various traditional medical systems, and thus could represent a promising source of antimicrobials. To establish the scientific basis for the therapeutic actions of traditional plant medicines, we provide a general workflow for evaluating the anti-infective properties of crude extracts from plants. We provide guidance starting from plant collections in the field and the creation of herbarium voucher specimens, moving to the processing of plants by drying, grinding, and extracting the plant parts collected, and finally ending with the antimicrobial investigation of these plant extracts. In this protocol, we provide a description of our workflow for the growth inhibitory evaluation of plant extracts against common human pathogenic bacteria.
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Antiinfecciosos/química , Antiinfecciosos/farmacología , Bacterias/efectos de los fármacos , Extractos Vegetales/química , Extractos Vegetales/farmacología , Plantas Medicinales/química , Medicina Tradicional/métodosRESUMEN
We modified rapid polymyxin Nordmann-Poirel (RPNP) test, called rapid colistin disk elution (RCDE) test, for detecting colistin resistance in Gram-negative bacilli and evaluated its performance compared with colistin broth disk elution (CBDE) test recommended by Clinical and Laboratory Standards Institute (CLSI). The RCDE test was performed by using a 10-µg colistin disk in 2.7 mL volume (final colistin concentration of 3.7 µg/mL) of either cation-adjusted Mueller-Hinton broth or phenol red broth base media with bacterial inoculum of 1-µL loop, and 1-4 and 16-20 hr incubation for Enterobacteriaceae and Acinetobacter baumannii isolates, respectively. Both tests were evaluated in 236 Enterobacteriaceae and 49 A. baumannii isolates using broth microdilution as reference method. Among the Enterobacteriaceae isolates, categorical agreement and very major error (VME or false intermediate susceptibility) rate were 98.3% and 5.4%, respectively, for the RCDE test, compared with 97.9% and 7.1%, respectively, for the CBDE test. Both tests had major error (ME or false resistance) rate of 0.6%. For the A. baumannii isolates, the RCDE and CBDE tests gave high VME rates of 8.3% and 16.7%, respectively. The RCDE test showed good performance comparable with the CBDE test but is cheaper and more rapid (3 hr) and convenient, thus suggesting as an alternative for detecting colistin resistance among Enterobacteriaceae in low-income countries.
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Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/farmacología , Colistina/farmacología , Farmacorresistencia Bacteriana , Enterobacteriaceae/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Genes Bacterianos , Humanos , Reproducibilidad de los ResultadosRESUMEN
Helicobacter pylori is a major infective etiological agent of the upper gastrointestinal tract diseases. The bacterium exhibits resistance to various conventional antibiotics, being usually challenging for eradication. Since there is an urge to consider alternative therapeutic strategies, the aim of the study was to examine selected essential oils of plants belonging to families Cupressaceae (Juniperus communis) and Lamiaceae (Hyssopus officinalis, Salvia officinalis, Melissa officinalis, Lavandula angustifolia, Ocimum basilicum and Thymus serpyllum) against H. pylori, using an improved microdilution broth method. The oils were examined in concentration range from 0.03 to 4⯵L/mL. The method comprises Brain-heart infusion broth supplemented with yeast extract, horse serum and IsoVitaleX. After 3â¯day incubation, an equal volume of double strengthen Christensen's urea was added into each well and incubated for additional 4â¯h. In wells with present H. pylori, the medium changed color from yellow to purple, allowing MIC determination even without a microtitre plate reader. The microtitre format method is convenient as it is less expensive, easier to perform and requires less amount of an anti-H. pylori agent. The improved method enhances specificity to H. pylori, as fast urease activity is almost an exclusive property of this bacterium. The application of the second step incubation with Christensen's urea decreases the possibility of false positive/negative results due to contaminant growth or commonly poor H. pylori growth. Among the examined oils, J. communis, H. officinalis and O. basilicum were not active with the highest applied concentrations, while the most active was T. serpyllum, with MIC 2.0-4.0⯵L/mL. This is the first report on essential oils activity of T. serpyllum and H. officinalis against H. pylori.
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Antiinfecciosos/farmacología , Helicobacter pylori/efectos de los fármacos , Colorimetría/métodos , Medios de Cultivo/farmacología , Cupressaceae/química , Lamiaceae/química , Pruebas de Sensibilidad Microbiana , Aceites Volátiles/farmacología , Aceites de Plantas/farmacologíaRESUMEN
The efficiency of Rapid Polymyxin NP test for detection of colistin-resistant isolates was tested against a collection of 131 non-repetitive Klebsiella pneumoniae, including 98 colistin-resistant and 33 colistin-susceptible isolates. In addition, the performance of this test was compared with those of the automated systems, BD Phoenix™ and VITEK®2, and the Etest. Determination of imipenem and meropenem MICs showed that 95 of colistin-resistant (Col-R) isolates were also resistant to at least one carbapenem. Characterization of colistin resistance mechanisms showed that 75 out of 98 Col-R isolates were associated with the presence of alterations in the mgrB gene, while no mcr genes were detected among our isolates. Rapid Polymyxin NP correctly detected 97 out of 98 colistin-resistant isolates (Geometric mean MIC value 9.89â¯mg/L), except one ST147 K. pneumoniae harboring a wild-type mgrB gene (MIC: 8â¯mg/L), yielding a sensitivity 99%. The other methods gave more false-negative results with colistin-resistant strains; BD Phoenix™,VITEK®2, and the gradient Etest missed five, two and three colistin-resistant, respectively (95%, 98% and 97%). The Rapid Polymyxin NP test gave false positive results with six isolates, for which colistin MICs were 1-2â¯mg/L (specificity 82%). Despite the fact that Rapid Polymyxin exhibited lower specificity than other methods (82% versus 94%, 88% and 85%), it is easy-to-perform and rapid. Thus, these findings indicate that the Rapid Polymyxin NP test can be an initial tool for the detection of colistin-resistant isolates.