Surveillance of In Vitro Activity of Cefiderocol Against Carbapenem-Resistant Gram-Negative Clinical Isolates in a Tertiary Care Hospital.

INTRODUCTION: Antibiotic resistance among Gram-negative bacterial isolates is increasingly observed. With the emergence of carbapenem-resistant and pan-resistant pathogens, treating these resistant infections is becoming more challenging due to the limited number of effective drugs. There is a desperate need for the discovery of new antibiotics with novel mechanisms of action. Cefiderocol is one such novel antibiotic with a unique siderophore-based mechanism of action, which has been recently approved for clinical use against drug-resistant pathogens. The present study aims to identify the in vitro activity of cefiderocol against major carbapenem-resistant clinical isolates, including those resistant to colistin. MATERIALS AND METHODS: One hundred and one carbapenem-resistant clinical isolates were included in the study. Identification and antibiotic susceptibility testing were performed using the automated VITEK® 2 Compact (bioMérieux SA, Marcy-l'Étoile, France) identification and susceptibility testing system, except for colistin and cefiderocol. Colistin resistance in Enterobacterales and Pseudomonas aeruginosa was assessed using the agar dilution minimum inhibitory concentration method, while for Acinetobacter baumannii, broth microdilution method was employed. Cefiderocol susceptibility testing was conducted using the Kirby-Bauer disc diffusion method with 30 µg discs on standard Mueller-Hinton agar plates. For selected isolates, cefiderocol minimum inhibitory concentration detection was performed using broth microdilution with iron-depleted cation-adjusted Mueller-Hinton broth. RESULTS: Of the total 101 isolates, the majority (75, 74.25%) were Enterobacterales which included Klebsiella pneumonia (42, 41.58%) and Escherichia coli (33, 32.67%), followed by Pseudomonas aeruginosa (13, 12.87%) and Acinetobacter baumannii (10, 9.9%). Only three (2.97%) of the isolates were Stenotrophomonas maltophilia. Most of the isolates were susceptible to cefiderocol, with only four (3.96%) isolates showing resistance. Colistin resistance was observed in six (6.12%) of the isolates. There was a good correlation between disc diffusion testing and broth microdilution testing for the detection of cefiderocol-resistant isolates. No cross-resistance with colistin was observed, as all colistin-resistant isolates were uniformly susceptible to cefiderocol Conclusion: Cefiderocol is highly effective with good in vitro activity against the majority of carbapenem-resistant pathogens. While some isolates do show resistance, it is relatively uncommon. Given its safety profile compared to colistin, cefiderocol can serve as an alternative to colistin to treat carbapenem-resistant infections and it may be considered even for the management of colistin-resistant cases. Disc diffusion testing is a reliable method for identifying cefiderocol-resistant isolates in routine clinical and diagnostic laboratories, especially in resource-limited settings.

Setting epidemiological cut-off values relevant to MIC and disc diffusion data for Aeromonas salmonicida generated by a standard method.

The Clinical and Laboratory Standards Institute has published epidemiological cut-off values for susceptibility data generated at 22°°C and read after 44-48 h for florfenicol, oxolinic acid and oxytetracycline against Aeromonas salmonicida. The cut-off values for the minimum inhibitory concentration (MIC) and disc diffusion were derived from data obtained by 1 laboratory and 2 laboratories respectively. The present work reports the generation of susceptibility data from additional laboratories and the calculation of provisional cut-off values from aggregations of these data with previously published data. With respect to MIC data, the provisional cut-off values, derived from aggregations of the data from 4 laboratories, were ≤4 µg ml-1 for florfenicol, ≤0.0625 µg ml-1 for oxolinic acid and ≤1 µg ml-1 for oxytetracycline. For disc diffusion data, the provisional cut-off values derived from aggregations of the data from 5 laboratories were ≥30 mm for florfenicol, ≥32 mm for oxolinic acid and ≥25 mm for oxytetracycline. In addition, a cut-off value of ≥29 mm for ampicillin was derived from the aggregation of data from 4 laboratories.

A Comparison of Antibiotics' Resistance Patterns of E. coli and B. Subtilis in their Biofilms and Planktonic Forms.

BACKGROUND: A biofilm refers to a community of microbial cells that adhere to surfaces that are surrounded by an extracellular polymeric substance. Bacteria employ various defence mechanisms, including biofilm formation, to enhance their survival and resistance against antibiotics. OBJECTIVE: The current study aims to investigate the resistance patterns of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) in both biofilms and their planktonic forms. METHODS: E. coli and B. subtilis were used to compare resistance patterns in biofilms versus planktonic forms of bacteria. An antibiotic disc diffusion test was performed to check the resistance pattern of biofilm and planktonic bacteria against different antibiotics such as penicillin G, streptomycin, and ampicillin. Biofilm formation and its validation were done by using quantitative (microtiter plate assay) and qualitative analysis (Congo red agar media). RESULTS: A study of surface-association curves of E. coli and B. subtilis revealed that surface adhesion in biofilms was continuously constant as compared to their planktonic forms, thereby confirming the increased survival of bacteria in biofilms. Also, biofilms have shown high resistance towards the penicillin G, ampicillin and streptomycin as compared to their planktonic form. CONCLUSION: It is safely inferred that E. coli and B. subtilis, in their biofilms, become increasingly resistant to penicillin G, ampicillin and streptomycin.

Maximally stable extremal regions-based algorithm for automatic interpretation of disc-diffusion antibiotic sensitivity test.

Antibiotic resistance causes a major threat to patients suffering from infectious diseases. Accurate and timely assessment of Antibiotic Susceptibility Test (AST) is of great importance to ensure adequate treatment for patients and for epidemiological monitoring. Disc Diffusion Test (DDT) is a standard and widely used method for AST. Manual interpretation of DDT results is a tedious task and susceptible to human errors. Computer vision-based automated interpretation of DDT results will speed up the process and reduces the manpower requirement. This would assist the physician to initiate the antibiotic treatment for the patients on time and results in saving the patient's life. The crucial step in automatic interpretation of DDT result is to measure and present the diameter of zone of inhibition without manual intervention. The existing methods require manual interventions at various stages during inhibition zone diameter measurement for some typical cases. This issue is addressed in the present work through maximally stable extremal regions (MSER) based algorithm. Dataset consisting of 60 agar plate images that includes different agar medium, images having different resolution and visual quality is used to validate the proposed method. Experimental results demonstrated that there is a strong correlation between standard method and the proposed method.

In vitro and in vivo antibacterial activity of selected essential oil components against Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum causing bacterial soft rot of potato tubers.

Pectinolytic bacteria cause bacterial soft rot of potato tubers. The most significant losses occur during storage. The efficacy of essential oil (EO) components carvacrol, cinnamaldehyde, d-carvone, l-menthone, R-(+)-limonene and thymol was tested against Pectobacterium carotovorum subsp. carotovorum (Pcc) and Pectobacterium atrosepticum (Pa). Disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests were performed in vitro, as well as potato disc and whole tuber maceration tests in vivo. Under in vitro conditions, cinnamaldehyde was the most effective against both bacteria (MIC 0.5 µL/mL, MBC 1.5 µL/mL). Both bacteria were found to be more susceptible to d-carvone (MIC 1.5-2.5 µL/mL, MBC 2.5 µL/mL) and thymol (MIC 2.5-5 µL/mL, MBC 3-5 µL/mL). R-(+)-limonene was the least effective. Results from the potato tuber disc maceration test confirmed a significant antibacterial effect of cinnamaldehyde at a concentration of 1.5 µL/mL. No rotted area was observed on potato tuber discs after treatment with l-menthone at concentrations of 2.5 µL/mL and 10 µL/mL against Pcc. A more pronounced effect was obtained when carvacrol was used at concentrations of 5 µL/mL against Pcc and 10 µL/mL against Pa. Disease severity tests on potato tubers after soaking for 20 min at MIC concentration of the EO components followed by 7 days of incubation at room temperature and 15 °C confirmed the antibacterial activity of cinnamaldehyde (0.5 µl/ml), l-menthone (2.5 µl/ml) and carvacrol (5-10 µl/ml). Cinnamaldehyde, l-menthone, and carvacrol may be recommended for further testing to treat stored potato tubers.

Argyreia nervosa-driven biosynthesis of Cu-Ag bimetallic nanoparticles from plant leaves extract unveils enhanced antibacterial properties.

Our study specifically explores the biosynthesis of copper-silver bimetallic nanoparticles (Cu-Ag BMNPs) using Argyreia nervosa (AN) plant leaf green extract as a versatile agent for capping, reducing, and stabilizing. This biosynthesis method is characterized by its simplicity and cost-effectiveness, utilizing silver nitrate (AgNO3) and cupric oxide (CuO) as precursor materials. Our comprehensive characterization of the Cu-Ag BMNPs, employing techniques such as X-ray diffraction (XRD), UV-Vis spectrometry, scanning electron microscopy (SEM), Zetasizer, and Fourier transformed infrared spectrometry (FTIR). FTIR analysis reveals biofunctional groups and chemical bands, while SEM and XRD analyses provide morphological and structural details. To evaluate the antimicrobial properties of the Cu-Ag BMNPs, we conducted disc diffusion and minimum inhibitory concentration (MIC) assays against Escherichia coli (E. coli), with results compared to the standard gentamicin antibiotic. It is observed that the 2% and 5% CuO concentrations of AN Cu-Ag BMNPs exhibit substantial antibacterial activity in comparison to AN extract when tested on EPEC. Among these, the Cu-Ag BMNPs at a 2% concentration demonstrate higher antibacterial activity, potentially attributed to the enhanced dispersion of BMNPs facilitated by the lower CuO doping concentration. These two assays showcased the improved antimicrobial activity of Cu-Ag BMNPs, highlighting their synergistic effect, characterized by high MIC values and a broad zone of inhibition in the disc diffusion tests against E. coli. These results emphasize the significant antibacterial potential of the synthesized BMNPs, with a medicinal plant AN leaf extract playing a pivotal role in enhancing antibacterial activity.

Epidemiological cut-off values for Yersina ruckeri disc diffusion data generated by a standardised method.

In order to establish the meaning of data generated in antimicrobial agent susceptibility tests, it is necessary to develop internationally harmonised interpretive criteria. Currently, such criteria have not been developed for data generated in studies of the susceptibility of the fish pathogen Yersinia ruckeri. This work generated the data that would be required to set epidemiological cut-off values for the susceptibility data of this species that had been generated using a standardised disc diffusion method that specified the use of Mueller Hinton agar and incubation at 22°C for 24-28 h. Using this method, sets of inhibition zones data for 4 antimicrobial agents were generated by 3 independent laboratories. The data from these laboratories were aggregated and analysed using the statistically based normalised resistance interpretation. For ampicillin, florfenicol, oxytetracycline and trimethoprim-sulfamethoxazole the cut-off values calculated by this analysis were ≥16, ≥23, ≥24 and ≥30 mm, respectively. Evidence is presented demonstrating that the data for these 4 agents was of sufficient quantity and quality that they could be used by the relevant authorities to set internationally harmonised, consensus epidemiological cut-off values for Y. ruckeri.

ISSLS prize in clinical/bioengineering science 2024: How standing and supine positions influence nutrient transport in human lumbar discs?-A serial post-contrast MRI study evaluating interplay between convection and diffusion.

PURPOSE: The intervertebral disc being avascular depends on diffusion and load-based convection for essential nutrient supply and waste removal. There are no reliable methods to simultaneously investigate them in humans under natural loads. For the first time, present study aims to investigate this by strategically employing positional MRI and post-contrast studies in three physiological positions: supine, standing and post-standing recovery. METHODS: A total of 100 healthy intervertebral discs from 20 volunteers were subjected to a serial post-contrast MR study after injecting 0.3 mmol/kg gadodiamide and T1-weighted MR images were obtained at 0, 2, 6, 12 and 24 h. At each time interval, images were obtained in three positions, i.e. supine, standing and post-standing recovery supine. The signal intensity values at endplate zone and nucleus pulposus were measured. Enhancement percentages were calculated and analysed comparing three positions. RESULTS: During unloaded supine position, there was slow gradual increase in enhancement reaching peak at 6 h. When the subjects assumed standing position, there was immediate loss of enhancement at nucleus pulposus which resulted in reciprocal increase in enhancement at endplate zone (washout phenomenon). Interestingly, when subjects assumed the post-standing recovery position, the nucleus pulposus regained the enhancement and endplate zone showed reciprocal loss (pumping-in phenomenon). CONCLUSIONS: For the first time, present study documented acute effects of physiological loading and unloading on nutrition of human discs in vivo. While during rest, solutes diffused gradually into disc, the diurnal short loading and unloading redistribute small solutes by convection. Standing caused rapid solute depletion but promptly regained by assuming resting supine position.

Ampicillin susceptibility testing of Haemophilus influenzae in the routine clinical laboratory by the EUCAST methodology compared to broth microdilution and the presence of ftsI gene mutations.

OBJECTIVES: To investigate the prevalence of ampicillin resistance in Haemophilus influenzae and the diagnostic accuracy of the EUCAST recommended disc diffusion method to detect the increasingly prevalent ampicillin resistance due to the presence of PBP3 alterations based on mutations in the ftsI gene. METHODS: During a 6-month period all consecutive non-duplicate H. influenzae isolates were prospectively collected and stored. MICs of ampicillin were determined by broth microdilution (BMD). PCR was performed to detect mutations in the ftsI gene. Results of routine disc diffusion susceptibility testing, including the penicillin screening test in accordance with the current EUCAST methodology, as well as additional Etest results, were compared to the BMD as the reference method. RESULTS: In 102 isolates, the prevalence of ampicillin resistance was 28% (29/102) by BMD. There was a good correlation between MICs of ampicillin and the presence of a ß-lactamase and/or an ftsI gene mutation. The prevalence of ampicillin resistance was overestimated using the EUCAST method (33% (34/102)) and underestimated when an additional Etest was used (24% (24/102)) (not significant). The sensitivity and specificity of the EUCAST methodology for the detection of ampicillin resistance were 97% ((28/29); 95% CI, 82-100%) and 92% ((67/73); 95% CI, 83-97%), respectively. CONCLUSIONS: The prevalence of ampicillin resistance was 28%, as determined by BMD. Although the overall diagnostic accuracy of the EUCAST ampicillin disc diffusion was high, misclassification of ampicillin susceptibility may still occur.

Performance evaluation of Bruker UMIC® microdilution panel and disc diffusion to determine cefiderocol susceptibility in Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Achromobacter xylosoxidans and Burkolderia species.

PURPOSE: Cefiderocol susceptibility testing (AST) represents an open challenge for clinical microbiology. Herein, we evaluated the performance of the UMIC® Cefiderocol broth microdilution (BMD) test and disc diffusion on Gram-negative species. METHODS: UMIC® Cefiderocol BMD test, disc diffusion and reference BMD were in parallel performed on a collection of 256 clinical isolates. Categorical agreement (CA), essential agreement (EA), bias, major errors (MEs) and very major errors (VMEs) were calculated for both AST methods. RESULTS: The UMIC® Cefiderocol BMD strip exhibited an EA < 90% (85.5%), a CA higher than 90% (93.7%) and a low number of VMEs (n = 4, 4.2%) and MEs (n = 12, 7.4%). UMIC® Cefiderocol identified 96.2% of the resistant isolates [Enterobacterales, (39/40); P. aeruginosa (19/19); A. xylosoxidans (5/6); S. maltophilia (5/6); Burkholderia spp. (8/8)]. Disc diffusion showed a high CA (from 94.9 to 100%) regardless of disc manufacturer in Enterobacterales, P. aeuroginosa, A. baumannii and S. maltophilia. However, high rates of results falling in the area of technical uncertainty (ATU) were observed in Enterobacterales (34/90, 37.8%) and P. aeruginosa (16/40, 40%). Disc diffusion showed a poor performance in A. xylosoxidans and Burkholderia spp. if PK/PD breakpoint was used (overall, 5/9 VMEs; in contrast, the use of P. aeruginosa-specific breakpoints resulted in 100% of CA with 24.6% of results in the ATU). CONCLUSION: In conclusion, disc diffusion and UMIC® Cefiderocol are valid methods for the determination of cefiderocol susceptibility. Given the high number of results in the ATU by disc diffusion, a combined use of both AST methods may represent a solution to overcome the challenge of cefiderocol susceptibility testing in routine microbiology laboratories.

Unveiling Annona Reticulata's Bioactive Arsenal for Enhanced Antibiotic Effects.

OBJECTIVE: To study the antibacterial and phytochemical activities of bioactive elements in the leaves of Annona reticulata Linn, a historically used Bangladeshi medicinal plant. METHODS: Shade-dried and crushed plant leaves were soaked with various solvents to obtain samples for different chemical analyses. All extracts were selected for antimicrobial, physicochemical, and Pharmacological investigations. The antimicrobial activity was evaluated using disc diffusion assay, and broth microdilution methods determined potentiation of the activities of the antibiotic antibacterial activity of the plant extracts was investigated using either gram-positive or gram-negative pathogenic wild-type bacteria. RESULTS: From the initial phytochemical and pharmacological studies, it was clear that all extracts, methanol, chloroform, and ethyl acetate, of the leaves of A. reticulata, were proven to process potent bioactive constituents. While differential antimicrobial properties were found to be possessed by all extracts, methanolic extract was the most potent one against all tested microorganisms. It also has potentiated the activities of antibiotics in E. coli. CONCLUSION: Bioactive constituents in the plant extracts were shown to possess phytochemical and antimicrobial activities. More investigation is needed to segregate the chemical components responsible for the respective phytochemical and antimicrobial activities.

Comparison of the antimicrobial photocatalytic activities of SiO2 and Au@SiO2 nanostructures in water decontamination.

Photocatalytic disinfection of Escherichia coli suspension by silicon dioxide nanoparticles and silicon dioxide/gold nanocomposite in a batch reactor is investigated experimentally and results are compared. Silica nanoparticles were synthesized by Stöber method and pulsed laser ablation method was employed to prepare gold nanoparticles in distilled water. Composition of two nanoparticles species was carried out, using the second harmonic pulse of Nd:YAG laser, whose wavelength is in the absorption spectra of gold nanoparticles. Results confirm a decrease in the bandgap energy of silica nanoparticles after composition. Escherichia coli were selected as an indicator of the microbial water contamination. Disk diffusion method was used to evaluate the antimicrobial potential of SiO2 and Au@SiO2 nanostructures. Photocatalytic activities of both nanostructures were examined in dark, and under the irradiation of UV and visible light. In all conditions, the performance of Au@SiO2 nanocomposites was higher than SiO2 nanoparticles. In dark condition the higher biocidal nature and activity of Au nanoparticles and for the case of UV radiation, decreasing the bandgap energy and recombination rate of SiO2 nanoparticles after composition with Au increased the efficiency. For the case of visible light radiation, surface plasmon resonances effects, and local heat of Au nanoparticles were responsible for increasing the efficiency. RESEARCH HIGHLIGHTS: Doping large bandgap semiconductors nanostructures, such as silica with metal nanoparticles, such as gold will improve their photocatalytic activity to work in visible light. In this mechanism, gold nanoparticles act as effective traps to prevent the recombination of photogenerated electron-hole pairs. Other mechanisms, such as Schottky barrier formation, surface plasmon resonance absorption of gold nanoparticles, and biocidal nature of the gold nanoparticles are effective in increasing the efficiency of Au doped silica nanostructures.

Systematic analysis of antimicrobial activity, phytochemistry, and in silico molecular interaction of selected essential oils and their formulations from different Indian spices against foodborne bacteria.

Essential oils (EOs) from Indian spices like Elettaria cardamomum (L.) Maton (small green cardamom), Syzygium aromaticum (L.) Merr. & L.M. Perry (clove), Cinnamomum zeylanicum Blume (cinnamon quills), and Cinnamomum tamala (Buch.-Ham.) T. Nees & C. H. Eberm (Indian bay leaves) exhibit a broad spectrum range of biological activity including antibacterial and antifungal activity. Yet, there is a lack of data regarding the antimicrobial activity of their formulations. Also, the link between the antimicrobial effect of individual EO with their chemical composition and molecular interaction with bacterial pathogens has not been systematically explored. Therefore, the objectives of the current study were to evaluate the antimicrobial activity and phytochemical characterization of EOs and to bridge the gap between them through in-silico molecular interactions. The antibacterial activity of EOs of four different spices and their formulations against foodborne pathogens such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa was evaluated using the disc volatilization method. The chemical profile of the individual EO was determined through GC-MS analysis and molecular interactions of identified major components with bacterial proteins were carried out through molecular docking studies. All EOs and their formulations exhibited antibacterial activity ranging from 5.92 to 24.55 mm and 11-23.52 mm, respectively. Among all EOs, cinnamon and formulation C (cardamom: cinnamon- 2:1) exhibited the highest antibacterial activity. The composition of the EOs included sesquiterpenes, monoterpenoids, monoterpenes, and, phenylpropanoids such as (E)-cinnamaldehyde, δ-cadinene, α-copaene, eugenol, caryophyllene, eugenol acetate, methyl eugenol, menthadiene, eucalyptol, α-terpinyl acetate, and sabinene. Furthermore, docking study revealed that the abundant compounds from cinnamon EO mainly α-copaene and δ-cadinene had a high binding affinity towards the bacterial essential proteins which increases the bacterial susceptibility towards cinnamon EO. The selected EOs and their formulations were systematically analysed and they were effective against foodborne pathogens. The current findings suggest the application of these EOs against food pathogens with further research.

Comparative evaluation of antifungal susceptibility testing methods for Rhizopus species isolates.

Background and Purpose: The mainstay of treatment for COVID-19-associated mucormycosis was liposomal Amphotericin B. Other antifungal agents, such as posaconazole and isavuconazole, were used as well. The Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing recommend broth microdilution methods for antifungal susceptibility testing. In this regard, the present study aimed to see what potency and zone diameters correlate with the gold standard broth microdilution method. Materials and Methods: All the isolates were identified by matrix-assisted laser desorption ionization-time-of-flight. In total, 127 isolates of 83 Rhizopus oryzae complex and 44 isolates of Rhizopus microsporus complex were selected. Anti-fungal susceptibility testing by disc diffusion and E-test was performed on Mueller Hinton Agar and compared with the CLSI broth microdilution method of Anti-fungal susceptibility testing. Results: Percentage agreement was found to be more in the case of the E test than the disc diffusion method. In the case of R. oryzae, posaconazole had 98.79% agreement with broth microdilution followed by Isavuconazole (97.59%), Itraconazole (96.38%), and Amphotericin B (91.56%). Conclusion: Disc diffusion correlates well with broth microdilution, although its correlation is weaker when compared to the E test. Effective concentration of Amphotericin B discs for antifungal susceptibility testing depends on the specific Rhizopus species.

Comparative Evaluation of Broth Microdilution With Disc Diffusion and VITEK 2 for Susceptibility Testing of Colistin on Multidrug-Resistant Gram-Negative Bacteria.

Background The rise of antibiotic resistance, particularly in Gram-negative bacteria, poses a significant global health threat. Colistin, a last-resort antibiotic, has witnessed renewed use. However, accurate susceptibility testing for colistin is challenging, with various methods available, leading to potential discrepancies. Ensuring reliable testing is crucial for effective patient treatment and antimicrobial stewardship. This study addresses the need to compare different colistin susceptibility testing methods, providing insights into their accuracy and relevance in clinical settings. Methods In this one-year prospective observational cross-sectional study conducted at Indira Gandhi Institute of Medical Sciences (IGIMS), Bihar, India, a tertiary care hospital from July 2021 to June 2022, we aimed to evaluate the concordance between two widely used methods, VITEK 2 and Disc Diffusion, for antibiotic susceptibility testing in clinical multidrug-resistant Gram-negative bacterial isolates. These isolates, including species like Klebsiella pneumoniae, Acinetobacter baumannii, Klebsiella oxytoca, Pseudomonas aeruginosa, Citrobacter freundii, and Escherichia coli, were isolated from various clinical specimens. After rigorous species-level identification and quality control measures, antibiotic susceptibility testing was performed using both methods, and their agreement was assessed through Percentage Agreement analysis. Results In our study, we isolated and identified bacterial isolates from 105 patients, with a mean age of 47.30 years, demonstrating a wide age range. Pus samples were the most common type (25.7%), and K. pneumoniae was the most prevalent organism (45.7%). Antibiotic resistance patterns revealed significant challenges in treating infections caused by K. pneumoniae and A. baumannii, with resistance rates exceeding 70% for certain antibiotics. Among the 48 isolates of K. pneumoniae, the agreement was 93.8%, with 89.6% being sensitive and 6.3% being resistant by Disc Diffusion, while VITEK 2 indicated 0% resistance. E. coli isolates (n=21) had an agreement of 90.5%, with 90.5% sensitivity and 9.5% resistance by Disc Diffusion, and no resistance by VITEK 2. Conclusion The comparative analysis of antibiotic susceptibility testing methods reveals the superior performance of the VITEK 2 system, particularly in sensitivity and negative predictive value, emphasizing its potential as a reliable tool for guiding antibiotic therapy decisions.

Actividad antimicrobiana de adhesivo ortodóntico con nanopartículas de plata sobre Streptococcus mutans / Antimicrobial activity of orthodontic adhesive with silver nanoparticles on Mutans streptococci / Atividade antimicrobiana de adesivo ortodôntico com nanopartículas de prata sobre streptococcus mutans

La aparatología fija usada en ortodoncia dificulta una adecuada higiene bucal, en estas condiciones el de-sarrollo de lesiones cariosas puede ser una complicación, uno de los principales agentes etiológicos involu-crados es Streptococcus mutans. La nanotecnología con plata tiene una aplicación preventiva importante en biomateriales dentales. Objetivo: Se determinó la actividad antimicrobiana sobre Streptococcus mutans de nanopartículas de plata (AgNPs) incluidas en adhesivos ortodónticos a diferentes concentraciones. Materia-les y métodos: En 20 cajas Petri con Streptococcus mutans inoculada en agar Müller-Hinton suplementado con 5% de sangre, se colocaron 6 discos de papel, 4 embe-bidos con AgNPs incluidas en un adhesivo orto-dóntico a concentraciones de 25, 75, 125 y 175 ppm, y 2 discos controles con clorhexidina al 0.12% y agua destilada. Se determinó la capacidad antimicrobiana en función de promedios de halos de inhibición a las 48 horas de incubación, en comparación con la escala de Duraffourd y la clorhexidina 0.12%. Resultados: A 25 ppm no existió capacidad antibacteriana, a 75 ppm el 50% alcanzó sensibilidad límite, pero el 100% de las muestras a 125 y 175 ppm consiguieron sensibilidad límite, sin embargo, la clorhexidina al 0,12% presentó mayor sensibilidad entre media 60% y sumamente sensible 40%. Conclusión: Las nanopartículas de plata con tamaño inferior a 100 nm, incluidas a 125 y 175 ppm en adhesivos de ortodoncia poseen actividad anti-microbiana sobre Streptococcus mutans, sin embargo, en el tiempo de estudio no alcanzan la sensibilidad de la clorhexidina al 0.12%.

The fixed appliances used in orthodontics make proper oral hygiene difficult, in these conditions the develop-ment of carious lesions can be a complication, one of the main etiologic agents involved is Mutans streptococci. It was determined that silver nanotechnology has an important preventive application in dental biomaterials. Objective: Antimicrobial activity on Mutans streptococci of silver nanoparticles (AgNPs) included in orthodon-tic adhesives at different concentrations. Materials and methods: In 20 Petri dishes with Mutans streptococci inoculated in Müller-Hinton agar supplemented with 5% blood, 6 paper discs were placed, 4 soaked up with AgNPs included in an orthodontic adhesive at concentrations of 25, 75, 125 and 175 ppm, and 2 control discs with 0.12% chlorhexidine and distilled water. Antimicrobial capacity was determined based on averages of inhibition halos at 48 hours of incubation, compared to the Duraffourd scale and 0.12% chlorhexidine. Results:At 25 ppm there was no antibacterial capacity, at 75 ppm 50% reached limit sensitivity, but 100% of the sam-ples at 125 and 175 ppm achieved limit sensitivity, however, chlorhexidine 0.12% showed higher sensitivity be-tween average 60% and highly sensitive 40%. Conclusión: Silver nanoparticles smaller than 100 nm, included at 125 and 175 ppm in orthodontic adhessives, have antimicrobial activity on Strptococcus mutans, however, when studying, they don't reach the sensitivity of chlorhexidine at 0.12%.

Os aparelhos fixos utilizados em ortodontia dificultam uma higiene bucal adequada, nessas condições o desenvolvimento de lesões cariosas pode ser uma complicação, um dos principais agentes etiológicos envol-vidos é o Streptococcus mutans. A nanotecnologia com partículas de prata tem uma importante aplicação pre-ventiva em biomateriais dentários. Objetivo: Determinou-se a atividade antimicrobiana das nanopartículas de prata (AgNPs) incluídas em adesivos ortodônticos em diferentes concentrações sobre Streptococcus mutans. Materiais e métodos: Em 20 placas de Petri com Streptococcus mutans inoculadas em ágar Müller-Hinton suplementado com 5% do sangue, foram colocados 6 discos de papel, 4 ensopados com AgNPs incluídos em um adesivo ortodôntico nas concentrações de 25, 75, 125 e 175 ppm e 2 discos de controle com 0,12% de clorexidina e água destilada. O efeito antimicrobiano foi determinado com base nas médias de halos de inibição às 48 horas de incubação, em comparação com a escala de Duraffourd e com clorexidina a 0,12%. Resultados: A 25 ppm não havia capacidade antibacteriana, a 75 ppm 50% atingiram a sensibilidade limite, mas 100% das amostras a 125 e 175 ppm atingiram a sensibilidade limite, no entanto, 0,12% de clorexidina apresentou maior sensibilidade entre 60% em média e 40% altamente sensíveis. Conclusão: Nanopartículas de prata menores que 100 nm, incluídas em 125 e 175 ppm em adesivos ortodônticos, têm atividade antimi-crobiana em Streptococcus mutans, no entanto, no tempo

Susceptibility of dermatophytic fungi to commonly used disinfectants / Suscetibilidade de fungos dermatófitos a desinfetantes comumente utilizados

This study aimed evaluate the antidermatophytic activity of three commercial disinfectants commonly used for environmental control of microorganisms in veterinary medicine. Sodium hypochlorite at 40 µL/mL, chloro-phenol derived at 30 µL/mL and chlorhexidine digluconate at 66.7 µL/mL were tested against 14 strains of dermatophytes, identified as Microsporum canis (n: 3) and Microsporum gypseum (n: 11). The tests was performed in accordance with guidelines of the Clinical and Laboratory Standards Institute (CLSI), documents M38-A2 and M51-A, adapted to disinfectants. In the microdilution broth test, chlorhexidine digluconate had MIC values (Minimum Inhibitory Concentration) of 4.16 µL/mL and MCF (Minimum Fungicidal Concentration) from 4.16 to 8.33 µL/mL, while chloro-phenol derived obtained MIC and MCF of 1.87 µL/mL, and both disinfectants had fungicidal activity at concentrations below the recommended. Sodium hypochlorite obtained MIC from 10 to 80 µL/mL and MFC of 40 to 80 µL/mL, requiring at most isolates twice the recommended concentration to achieve same activity. In the disc diffusion test, the mean inhibition zones for chlorhexidine digluconate was 10.53 mm, for chloro-phenol of 9.9 mm and for sodium hypochlorite was 6.2 mm. Chlorhexidine digluconate and chloro-phenol presented a significant reduction in the growth of dermatophytes, while sodium hypochlorite in concentration recommended showed a low antifungal activity against tested isolates.

O objetivo do estudo foi avaliar a atividade antidermatofítica de três desinfetantes comerciais frequentemente utilizados no controle ambiental de micro-organismos em medicina veterinária. Hipoclorito de sódio a 40 µL/mL, derivado de clorofenol a 30 µL/mL e digluconato de clorexidine a 66.7 µL/mL foram testados contra 14 cepas de dermatófitos, identificados como Microsporum canis (n: 3) e Microsporum gypseum (n: 11). Foram utilizadas as diretrizes do Clinical and Laboratory Standard Institute (CLSI), documentos M38-A2 e M51-A, com adaptações para desinfetantes. Na microdiluição em caldo, digluconato de clorexidine apresentou valores de CIM (Concentração Inibitória Mínima) de 4.16 µL/mL e CFM (Concentração Fungicida Mínima) entre 4.16 a 8.33 µL/mL; derivado de clorofenol obteve CIM e CFM de 1.87 µL/mL, demonstrando que ambos os desinfetantes apresentaram atividade fungicida em concentrações inferiores às recomendadas. O hipoclorito de sódio demonstrou CIM entre 10 a 80 µL/mL e CFM de 40 a 80 µL/mL, requerendo duas vezes a concentração recomendada pelo fabricante para obter atividade fungicida frente a maioria dos isolados fúngicos testados. No teste de disco-difusão, a média das zonas de inibição do digluconato de clorexidine foi de 10.53 mm; do derivado clorofenol 9.9 mm e do hipoclorito de sódio 6.2 mm. O digluconato de clorexidine e o derivado cloro-fenol apresentaram redução significante no crescimento dos dermatófitos testados, enquanto o hipoclorito de sódio, na concentração recomendada, demonstrou baixa atividade antifúngica contra os dermatófitos testados.

Estudo comparativo da susceptibilidade de isolados clínicos de Cryptococcus neoformans (Sanfelice, 1895) frente a alguns antifúngicos de uso hospitalar e extratos vegetais obtidos de plantas medicinais da região semiárida sergipana / Comparative study of the susceptibility of clinical isolates of Cryptococcus neoformans (Sanfelice) against some antifungal agents of hospital use and plant extracts obtained from medicinal plants of the semiarid Sergipe region, Brazil

O uso de plantas medicinais no combate as micoses é uma prática comum nas comunidades rurais e, neste contexto, o objetivo desse trabalho foi analisar o perfil de sensibilidade de isolados clínicos de C. neoformans frente a extratos brutos aquosos e antifúngicos de uso hospitalar utilizando a técnica de difusão em disco. Esses produtos naturais foram obtidos de plantas medicinais popularmente utilizadas por comunidades do sertão sergipano. Foram analisados os extratos brutos aquosos de juazeiro (Ziziphus joazeiro Mart.), catingueira (Caesalpinia pyramidalis Tul.), quixabeira (Bumelia sartorum Mart.) e jatobá (Hymenaea courbaril L.). Do juazeiro foi testado o extrato preparado a partir do infuso da entrecasca e da decocção da folha. Da catingueira foi utilizado o extrato preparado a partir do infuso das folhas. Da quixabeira o extrato utilizado foi preparado a partir da decocção da entrecasca e do jatobá maceração da entrecasca. Todos esses produtos naturais foram submetidos aos seguintes tratamentos: exposição ou não a luz ultravioleta e autoclavagem (121ºC por 10minutos). Em paralelo as leveduras patogênicas foram testadas frente aos seguintes antifúngicos de uso hospitalar: anfotericina B, fluconazol, Itraconazol, Miconazol e cetoconazol. Todos os extratos brutos aquosos apresentaram ação antifúngica frente a todas as linhagens clínicas de Cryptococcus neoformans. O tratamento de submeter à autoclavagem e exposição à luz ultravioleta apresentaram melhores resultados de ação antifúngica. Sendo que o tratamento de autoclavar o extrato bruto aquoso prevaleceu estatisticamente com os melhores resultados. Outros estudos de atividade antimicrobiano são necessários para corroborar a ação antimicótica dos produtos natuais testados, como pro exemplo killer-time e fracionamento do teste de micodiluição. No teste de sensibilidade dos antifúngicos realizado foi demonstrado que as leveduras apresentaram resistência preocupante ao fluconazol e a itraconazol pelo método de difusão em disco. Para novos conhecimentos desse perfil de resistência há necessidade de testes de melhor acurácia, como por exemplo, microdiluição. Para tanto, deve-se padronizar os testes de sensibilidade quando há uso de produtos naturais oriundos de plantas medicinais, além de fornecer alternativas de uso aos pacientes cometidos por essa levedura com fornecimento de dados científicos que comprovem a ação dos produtos naturais e plantas medicinais de largo uso no sertão sergipano.

The use of medicinal plants to combat mycoses is a common practice in rural communities, and, in this context, the aim of this study was to analyze the sensitivity of clinical isolates of C. neoformans in relation to aqueous crude extracts and antifungal agents of hospital use using the disc diffusion technique. These natural products were obtained from medicinal plants popularly used empirically by backland communities in Sergipe, Brazil. The aqueous crude extracts of Ziziphus joazeiro Mart., Caesalpinia pyramidalis Tul., Bumelia sartorum Mart. and Hymenaea courbaril L. were analyzed. From the Ziziphus joazeiro Mart., we tested the extract prepared from the infusion of the inner bark and the decoction of the leaf. From the Caesalpinia pyramidalis Tul., the extract used was prepared from the infusion of the leaves. From Bumelia sartorum Mart., the extract used was prepared from the decoction of the bark, and from the Hymenaea courbaril L. we prepared the extract from the maceration of the inner bark. All these natural products were subjected to the following treatments: exposure to ultraviolet light or not and autoclaving (121°C for 10minutes). Amphotericin B, fluconazole, itraconazole, miconazole and ketoconazole were tested. All aqueous crude extracts showed antifungal activity against all clinical strains of Cryptococcus neoformans. The treatment that underwent autoclaving and exposure to ultraviolet light showed better results for antifungal action. The treatment with autoclaving of the aqueous crude extract statistically prevailed with the best results. There is the need to perform some treatments using these natural products based on the tested medicinal plants for better antifungal activity against this pathogenic yeast so they become more effective. In the antifungal susceptibility test performed, it was demonstrated that the yeast had worrying resistance to fluconazole and itraconazole by the disc diffusion method. FOr further knowledge on this resistance profile, there is the need of tests with greater accuracy, such as the microdilution test. To do so, susceptibility testing must be standardized when there is the use of natural products derived from medicinal plants, in addition to the provision of alternative uses by patients affected by this yeast, providing scientific data demonstrating the use and action of the natural products and medicinal plants of wide use in Sergipe, Brazil.

Comparação de métodos para avaliação da atividade antimicrobiana e determinação da concentração inibitória mínima (cim) de extratos vegetais aquosos e etanólicos / Comparison of methods for evaluation of antimicrobial activity and determination of minimum inhibitory concentration (mic) of aqueous and ethanol plant extracts

Vários estudos estão sendo conduzidos para a descoberta de novos agentes antimicrobianos provenientes de plantas, para que possam ser utilizados em produtos farmacêuticos, cosméticos e na indústria alimentícia. A ausência de padronização de métodos utilizados para a avaliação de extratos vegetais com potencial antimicrobiano dificulta a comparação de resultados. Considerando a necessidade de estabelecer um método com resultados consistentes para avaliar a atividade antimicrobiana dos extratos vegetais, este trabalho propôs-se a avaliar a atividade antimicrobiana e determinar a concentração mínima inibitória de extratos de plantas da família Myrtaceae sobre diferentes micro-organismos, utilizando três métodos para avaliação de antimicrobianos. Os métodos empregados foram microdiluição em caldo e difusão em ágar por disco e poço. Foram avaliados os extratos de Psidium guajava, Myrciaria cauliflora e Syzygium cumini sobre bactérias Gram-positivas, negativas e levedura. Em geral, a inibição promovida pelos extratos no teste de difusão em ágar por poço foi maior do que os valores obtidos por disco, independentemente do extrato vegetal testado. Contudo, a atividade inibitória de todos os micro-organismos só pôde ser determinada com o método de microdiluição em caldo, que também apresentou os resultados mais reprodutíveis, e mostrou-se o mais econômico e confiável para se avaliar a atividade antimicrobiana de extratos vegetais quando comparado aos outros métodos.(AU)

Several studies have been conducted to discover new antimicrobial agents from plants to be used in pharmaceuticals, cosmetics and in the food industry. The lack of standardized methods for the evaluation of plant extracts with antimicrobial potential complicates the comparison of results. Taking into consideration the need to establish a method with consistent results to evaluate the antimicrobial activity of plant extracts, this study aimed to evaluate the antimicrobial activity of extracts of some plants from the Myrtaceae family on different micro-organisms based on a comparative assay with three methods that are commonly used for the assess antimicrobials. The methods used were broth microdilution, and agar diffusion by disc and well. The evaluated extracts were those of Psidium guajava, Myrciaria cauliflora, and Syzygium cumini for Gram-positive and negative bacteria and yeast. In general, inhibition extracts promoted by the agar diffusion test by well was higher than the values ​​obtained by disc, regardless of the plant extracts tested. However, the inhibitory activity of all micro-organisms was only possible to be determined with the microdilution broth method, which also presented the more reproducible results, and proved to be the most economic and reliable way to evaluate the antimicrobial activity of plant extracts in contrast with other methods.(AU)

Screening antimicrobial activity of various extracts of Urtica dioica

Urtica dioica or stinging nettle is traditionally used as an herbal medicine in Western Asia. The current study represents the investigation of antimicrobial activity of U. dioica from nine crude extracts that were prepared using different organic solvents, obtained from two extraction methods: the Soxhlet extractor (Method I), which included the use of four solvents with ethyl acetate and hexane, or the sequential partitions (Method II) with a five solvent system (butanol). The antibacterial and antifungal activities of crude extracts were tested against 28 bacteria, three yeast strains and seven fungal isolates by the disc diffusion and broth dilution methods. Amoxicillin was used as positive control for bacteria strains, vancomycin for Streptococcus sp., miconazole nitrate (30µg/mL) as positive control for fungi and yeast, and pure methanol (v/v) as negative control. The disc diffusion assay was used to determine the sensitivity of the samples, whilst the broth dilution method was used for the determination of the minimal inhibition concentration (MIC). The ethyl acetate and hexane extract from extraction method I (EA I and HE I) exhibited highest inhibition against some pathogenic bacteria such as Bacillus cereus, MRSA and Vibrio parahaemolyticus. A selection of extracts that showed some activity was further tested for the MIC and minimal bactericidal concentrations (MBC). MIC values of Bacillus subtilis and Methicillin-resistant Staphylococcus aureus (MRSA) using butanol extract of extraction method II (BE II) were 8.33 and 16.33mg/mL, respectively; while the MIC value using ethyl acetate extract of extraction method II (EAE II) for Vibrio parahaemolyticus was 0.13mg/mL. Our study showed that 47.06% of extracts inhibited Gram-negative (8 out of 17), and 63.63% of extracts also inhibited Gram-positive bacteria (7 out of 11); besides, statistically the frequency of antimicrobial activity was 13.45% (35 out of 342) which in this among 21.71% belongs to antimicrobial activity extracts from extraction method I (33 out of 152 of crude extracts) and 6.82% from extraction method II (13 out of 190 of crude extracts). However, crude extracts from method I exhibited better antimicrobial activity against the Gram-positive bacteria than the Gram-negative bacteria. The positive results on medicinal plants screening for antibacterial activity constitutes primary information for further phytochemical and pharmacological studies. Therefore, the extracts could be suitable as antimicrobial agents in pharmaceutical and food industry.

Urtica dioica u ortiga se utiliza tradicionalmente como medicina herbaria en el oeste de Asia. En esta investigación se estudia la actividad antimicrobiana de nueve extractos crudos de U. dioica, los cuales fueron preparados utilizando diferentes disolventes orgánicos y obtenidos a partir de dos métodos de extracción: el extractor Soxhlet (Método I), que incluía el uso de cuatro disolventes con acetato de etilo y hexano, y las particiones secuenciales (Método II) con un sistema de cinco disolventes (butanol). Las actividades antibacterianas y antifúngicas de extractos crudos fueron ensayados contra 28 bacterias, tres cepas de levadura y siete cepas fúngicas por la difusión en disco y el método de dilución en caldo. La amoxicilina se utilizó como control positivo para cepas de bacterias, vancomicina para Streptococcus sp., nitrato de miconazol (30μg/mL) como control positivo para los hongos y levaduras, y el metanol puro (v / v) como control negativo. El ensayo de difusión en disco se utilizó para determinar la sensibilidad de las muestras, mientras que el método de dilución en caldo se utilizó para la determinación de la concentración de inhibición mínima (CIM). El acetato de etilo y el extracto de hexano del método de extracción I (AE I y EH I) mostraron mayor inhibición contra algunas bacterias patógenas tales como Bacillus cereus, MRSA y Vibrio parahaemolyticus. Una selección de extractos que mostraron algún tipo de actividad se probó para el CIM y las concentraciones mínimas bactericidas (CMB). Los valores de CIM de Bacillus subtilis y de Staphylococcus aureus resistentes a la meticilina (MRSA) usando extracto de butanol mediante el método de extracción II (EB II) fueron: 8.33 y 16.33mg/ mL, respectivamente; mientras que el valor de MIC con el uso del extracto de acetato de etilo por el Método de extracción II (EAE II) para Vibrio parahaemolyticus fue 0.13mg/mL. Nuestro estudio mostró que el 47.06% de los extractos inhibieron bacterias Gram-negativas (8 de 17), y el 63,63% de los extractos también inhibieron bacterias Gram-positivas (7 de 11), además que estadísticamente la frecuencia de la actividad antimicrobiana fue de 13.45% (35 de 342), que de este porcentaje un 21.71% pertenece alos extractos de actividad antimicrobiana con el método de extracción I (33 de 152 de los extractos crudos) y un 6.82% del método de extracción II (13 de 190 de los extractos crudos). Sin embargo, los extractos crudos del método I exhibieron una mejor actividad antimicrobiana contra las bacterias Gram-positivas que las Gram-negativas. Los resultados positivos en la detección de plantas medicinales para la actividad antibacteriana constituye información primaria para la realización de nuevos estudios fitoquímicos y farmacológicos. Por lo tanto, los extractos podrían ser adecuados como agentes antimicrobianos en la industria farmacéutica y de alimentos.