Agar Dilution Method Research Articles

Antimicrobial Susceptibility Patterns and Antimicrobial Therapy of Infections Caused by Elizabethkingia Species

Background and Objectives: Elizabethkingia species have become significant sources of infections acquired in hospital settings and are commonly linked to high mortality rates. Antimicrobial resistance can be influenced by Elizabethkingia species, geographical location, antimicrobial susceptibility testing methods, and the time of bacterial isolation. There are distinct antimicrobial susceptibility patterns among species, and the investigation into potential antibiotic susceptibility variations among species is beneficial. There is no guidance on the treatment of Elizabethkingia species infections in the literature. Consequently, the purpose of this review was to elaborate on the antimicrobial susceptibility patterns of Elizabethkingia species through a scoping review of existing studies on the antibiograms of the Elizabethkingia species and on the illness caused by Elizabethkingia species. Materials and Methods: A comprehensive literature search in PubMed and Web of Science between 1 January 2000 and 30 April 2024 identified all studies, including those that examined antimicrobial susceptibility patterns and antimicrobial therapy of infections caused by Elizabethkingia species. I considered studies on antimicrobial susceptibility testing for Elizabethkingia species in which only broth microdilution methods and agar dilution methods were used. Results: The sensitivity levels of Elizabethkingia meningoseptica to piperacillin–tazobactam (5–100%), ciprofloxacin (0–43.4%), levofloxacin (30–81.8%), trimethoprim–sulfamethoxazole (0–100%), tigecycline (15–100%), minocycline (60–100%), and rifampicin (94–100%) varied. The sensitivity levels of Elizabethkingia anophelis to piperacillin–tazobactam (3.3–93.3%), ciprofloxacin (1–75%), levofloxacin (12–100%), trimethoprim–sulfamethoxazole (1.02–96.7%), tigecycline (0–52.2%), minocycline (97.5–100%), and rifampicin (20.5–96%) varied. The sensitivity levels of Elizabethkingia miricola to piperacillin–tazobactam (41.6–94.0%), ciprofloxacin (14–75%), levofloxacin (77.0–100%), trimethoprim–sulfamethoxazole (18.0–100%), tigecycline (50%), minocycline (100%), and rifampicin (66–85.7%) varied. Conclusions: The majority of the isolates of Elizabethkingia species were susceptible to minocycline and rifampin. This issue requires professional knowledge integration and treatment recommendations.

Fighting H. pylori with Medicinal Plants: A Study on Jordan's Traditional Remedies

Aims of the Study: This study was designed to evaluate the antimicrobial activity of some medicinal plants used among Jordanians for the treatment of gastritis and gastric ulcers against H. pylori. Moreover, plants' inhibitory activity against the H. pylori urease enzyme was also evaluated. Materials and Methods: The activity of 11 medicinal plants used by common people and herbalists to treat ulcers was evaluated against H. pylori (NCTC 11916). Ethanol and essential oil extracts from the tested plants were evaluated using a standard agar dilution method and the MICs were determined. Furthermore, the potential inhibitory effect of each preparation was tested against the enzyme urease using a kinetic colorimetric assay. Results: Cinnamomum cassia oil showed the highest efficiency against H. pylori with the lowest MIC (0.0122 mg.mL-1), followed by Origanum syriacum and Foeniculum vulgare (MICs of 0.39 mg.mL-1). Furthermore, significant urease inhibition activity was recorded for Carum carvi oil (IC50~0.45 mg.mL-1). C. cassia oil (IC50 ~2.8 mg.mL-1), Aloysia citriodora, and Artemisia Judaica (IC50 5.8 mg.mL-1) reported potential urease inhibition activities. Conclusion: Herbs used in Jordanian traditional medicine were found to have anti-H. pylori and significant urease inhibitory activity. These findings might support the use of medicinal plants as adjuvant or alternative therapy for the treatment of H. pylori.

A seemingly considerable increase in antimicrobial resistance in the Bacteroides fragilis group from blood cultures – the second national study in Denmark

Background Bacteroides fragilis group species are the most frequently encountered bacteria involved in anaerobic bacteraemia and associated with high mortality rates. In 2012, we performed the first national study of antimicrobial susceptibility in the B. fragilis group from blood cultures in Denmark. Objectives The purpose of the present study was to compare the antimicrobial susceptibility rates of piperacillin-tazobactam, meropenem, clindamycin and metronidazole in the B. fragilis group from blood cultures in Denmark in 2022 with susceptibility rates from 2012. In addition, we wanted to investigate whether changes to susceptibility was related to the overall use of the specified antimicrobial agents from 2012 to 2022. Methods Antimicrobial susceptibility testing was performed in accordance with EUCAST guidelines using the agar dilution method and the disc diffusion method. Results The study showed a seemingly considerable increase in resistance in the B. fragilis group (n = 234) to piperacillin-tazobactam from a reported 8.5% in 2012 to 42.7% in 2022. Resistance towards meropenem also increased from a reported 3.4% to 10.7%. Most of the increase in resistance for piperacillin-tazobactam and meropenem is caused by a recent EUCAST breakpoint change. Metronidazole still has the lowest resistance rate for the B. fragilis group (one isolate, 0.4%) in this study. The sales of piperacillin-tazobactam in the same period revealed a corresponding increase (+130%), whereas meropenem sales were stable. Conclusion The results underscore the need for timely routine antimicrobial susceptibility testing of B. fragilis group species and questions piperacillin-tazobactam monotherapy as empiric treatment for septic patients with a suspected abdominal source.

Evaluation of accuracy of Phenotypic methods in the detection of Methicillin Resistant Staphylococcus aureus

Abstract: Methicillin resistant Staphylococcus aureus (MRSA) is a variant of Staphylococcus aureus; responsible for a significant share of the infectious load. Objective: The current study was conducted to evaluate the accuracy of already in vogue phenotypic methods of identification of MRSA keeping in view the gold standard method of mec-A gene detection using Polymerase chain reaction (PCR) and to compare the sensitivity and specificity of different phenotypic methods (Cefoxitin Disc Diffusion, Oxacillin Disc Diffusion, Oxacillin Screen Agar, and MIC of Oxacillin by Agar Dilution Method) with the genotypic method (PCR). Method: A descriptive cross-sectional study was carried out at Microbiology Lab, Pakistan Railway Hospital, Rawalpindi from October 2021 to September 2022, after attaining the formal approval from Institutional Ethical Review Committee (Riphah/IIMC/IRC/21/73), using non-probability sampling technique. A total of 222 samples of Staphylococcus aureus were isolated from all the clinical specimens received at Microbiology lab at Pakistan Railway Hospital. Among those isolates, 150(67.5%) were Methicillin sensitive Staphylococcus aureus (MSSA) and 72(32.4%) were Methicillin Resistant Staphylococcus aureus (MRSA). The results of Phenotypic methods were compared with the results of PCR by using Chi-square formula. The sensitivity and specificity of Cefoxitin Disc Diffusion method was 62.5% and 96.6%, Oxacillin Disc Diffusion method was 65.3% and 93.3%, Oxacillin Screen Agar technique was 81.9% and 96% while that of Oxacillin MIC by Agar Dilution was 91.6% and 89.3% respectively. Oxacillin screen agar demonstrates the better phenotypic technique for detection of MRSA in routine practice.

Resistance tofluoroquinolones among Klebsiella pneumoniae isolates collected from patients referred to the teaching hospitals of Ardabil university of medical sciences in 2020

Background. Klebsiella pneumoniae (KP) is one of the most important causes of hospital-acquired infection and one of the most important causes of ventilator-associated pneumonia. During the present study, we investigated the resistance to fluoroquinolones among KP isolates collected from patients referred to hospitals affiliated with Ardabil University of Medical Sciences in 2020. Methods. In this descriptive, cross-sectional study, the minimum inhibitory concentration (MIC) of ciprofloxacin (CLX) was determined by the agar dilution method, and mutations in the gyrA and parC genes and the presence of resistance genes, such as accA, qnr, and qepA, were evaluated using the polymerase chain reaction method. Results. Out of 100 isolates, 43% (n = 43) were resistant to CLX. The MIC range of CLX was 0.5 µg/mL to 1024 µg/mL. Isolates with a high MIC of CLX were investigated for mutations in the gyrA and parC genes. In the investigation of mutations in gyrA, a substitution from serine to isoleucine was observed at position 83, while no mutation was found in parC. In 10 isolates (10%), the presence of the aac (6')-Ib-cr gene was detected, while qepA and qnr resistance genes were not observed in any of the isolates. Conclusion. Based on the findings, a high frequency of the aac (6')-Ib-cr gene was reported in this study. Since this gene is located on a plasmid, it can be easily transferred between KP strains in a hospital setting and leads to the spread of resistance to fluoroquinolones. Practical Implications. The emergence of bacterial resistant strains is on the rise and has become a serious public health problem worldwide. Infection with these strains leads to complicated diseases with worse outcomes, prolonged hospitalization, increased healthcare costs, an increased need to use second-line drugs with costs, and treatment failures.

Analysis on characteristics and multilocus sequence typing of Clostridium perfringens in western China.

The objective of this study was to identify and analyse the distribution characteristics, toxin genotyping and antimicrobial susceptibility of Clostridium perfringens and to investigate its resistance mechanisms and genetic characteristics. The MICs of various antibiotics against C. perfringens were determined using the agar dilution method, and resistance genes and toxin genotypes were detected by PCR. Genetic relationships were analysed using MLST. WGS was conducted on the DNB system and PacBio platforms. Analysis of 36 strains of C. perfringens revealed that the major toxin types were types C and F, with 86.1% of the strains isolated from bile samples. Of these, 30.6% of the strains exhibited MDR, with resistance rates of 75.0%, 52.8% and 52.8% for penicillin, clindamycin and ampicillin, respectively; however, no resistance to metronidazole and carbapenems was observed. MLST analysis identified 29 STs, including 14 novel types. ST221 and ST498 were the dominant types. The WGS revealed that the most prevalent virulence factors are plc (100.0%), nagH (100.0%), colA (100.0%), nanJ (100.0%), entB (100%), nanH (97.0%), entA (97.0%) and nanI (90.9%). Among these factors, the primary determinants of tetracycline resistance are tetA (66.7%) and tetB (78.8%), which represent the most frequently detected antibiotic resistance genes. This study indicates that the infection rate of C. perfringens is relatively high, with the majority of isolated strains exhibiting MDR. The observed high levels of antibiotic resistance, combined with the significant genetic diversity of these strains, suggest a potential public health risk.

In vitro Antibacterial Activity of Dye Compounds

Background: Methylene blue and some of its analogues have known antibacterial activity, however their exact mechanism of action is unknown Objective: In this study, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of several methylene blue analogues were determined against five bacterial strains, whereafter the data were used to create and validate a pharmacophore model. Methods: The agar dilution method was used to screen the analogues for antibacterial activity, while the broth microdilution method was used to determine their MIC and MBC. A pharmacophore model was constructed and validated using the rank score, fit value, enrichment factor (EF10%), hit rate (HR10%) and receiver operating characteristic area under the curve (ROC-AUC) as metrics. Results: Against Staphylococcus aureus, pyronin B (0.125 µg/ml) was more active than tetracycline (1 µg/ml) and pyronin Y (0.5 µg/ml), 1,9-dimethylmethylene blue (2 µg/ml), basic blue 3 (2 µg/ml), new methylene blue (2 µg/ml) and Nile blue (2 µg/ml) had similar activity compared to tetracycline. Pyronin B, 1,9-dimethylmethylene blue and new methylene blue were bactericidal. A pharmacophore model was created (rank score: 36.55, max. fit value: 3), which was able to identify active analogues out of the test set (EF10%: 2.83, HR10%: 28.57%, ROC-AUC: 0.84 ± 0.04). The pharmacophore model highlighted that a positive ionisable, aromatic ring as well as a hydrophobic moiety are important for antibacterial activity. Conclusion: Methylene blue analogues were found to have potent antibacterial activity and a pharmacophore model was created to understand the structural requirements for activity.

Relationship between the strength of biofilm production and the presence of pvl and mecA genes in Staphylococcus aureus isolated from skin and soft tissue infections

This research sought to investigate the association between the occurrence of the pvl and mecA genes and the strength of biofilm formation, as well as to assess the efficacy of vancomycin and ceftaroline against Staphylococcus aureus strains obtained from skin and soft tissue infections (SSTIs). A total of 134 S. aureus isolates were collected from SSTI patients and identified through standard microbiological techniques. Vancomycin and ceftaroline susceptibility testing were performed using the agar dilution and disc diffusion methods, respectively. PCR analysis was conducted to identify the nuc, mecA, and pvl genes. Biofilm production was measured using the tissue culture plate method. Methicillin-resistant S. aureus (MRSA) represented 58.2 % of the isolates. All isolates displayed biofilm-forming capability, with 10.4 % classified as high-grade biofilm producers, 85.7 % of which were positive for the mecA gene (P = 0.02). 16.4 % of the isolates had pvl gene and 59 % of PVL-positive strains identified as MRSA. Most of the low-grade biofilm producers had the pvl gene (P = 0.03). Vancomycin susceptibility was observed in 98.5 % of isolates, with an MIC₅₀ of 1 μg/mL in 51.4 % of cases. Among MRSA strains, 1.4 % exhibited intermediate resistance to vancomycin, with MICs between 4 and 8 μg/mL. No resistance to ceftaroline was found. The results demonstrate a significant association between biofilm production strength and the occurrence of the mecA and pvl genes; mecA correlated with increased biofilm production, while pvl was associated with lower biofilm levels. These findings offer valuable insights for future studies, suggesting that ceftaroline could be an effective alternative to vancomycin for treating MRSA-related SSTIs, particularly given the increasing resistance to vancomycin.

Clinical Outcomes and Molecular Characteristics of Bacteroides fragilis Infections.

Bacteroides fragilis is the most common opportunistic anaerobic pathogen. In the absence of appropriate antimicrobial therapy, mortality rates associated with B. fragilis group infections can reach as high as 50%. Therefore, we aimed to elucidate the clinical characteristics and outcomes of B. fragilis infections and the molecular genetic characteristics of B. fragilis isolates. Forty B. fragilis clinical isolates were collected at Hanyang University Hospital between January 2022 and December 2023. Antimicrobial susceptibility was tested using the agar dilution method. Whole-genome sequencing was conducted using the Illumina platform (Illumina, San Diego, CA, USA). Various multilocus sequence types of B. fragilis were identified, including ST149 (N=4), ST11 (N=4), ST1 (N=3), ST21 (N=2), and ST157 (N=1). The insertion sequence (IS) IS1187, located upstream of cfiA, was associated with high-level carbapenem resistance in the ST157 isolate. B. fragilis toxin genes (bft ) were identified in 30% of isolates. The most common comorbidities were diabetes mellitus (26.5%) and non-metastatic cancer (23.5%). Five patients (14.7%) died within 30 days, and two (5.9%) deaths were directly attributable to B. fragilis infection. The emergence of high-level MIC carbapenem-resistant B. fragilis ST157 has led to caution in the presence of B. fragilis infections.

The prevalence of carbapenem-resistant Enterobacterales and the emergence of novel ST11-KL30 carbapenem-resistant Klebsiella pneumoniae in Xinjiang, China

ObjectivesTo address the lack of research on the prevalence of carbapenem-resistant Enterobacterales (CREs) in Xinjiang, China, and elucidate the genomic characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) ST11-KL30. MethodsCREs were collected in Xinjiang from 2021 to 2023. The antimicrobial susceptibility testing of carbapenems was performed via agar dilution method. Whole-genome sequencing was completed on the Illumina platform, and subsequent genomic analyses of CRKP, such as sequencing typing, K-locus and O-locus identification, virulence score assessment, and phylogenetic analysis, were performed. The virulence of CRKP isolates was determined in vitro and in vivo, and biofilm formation was assessed by crystal violet staining. Additionally, the virulence plasmid was reconstructed, and the formation of CRKP ST11-KL30 was revealed based on genome data from public database. ResultsEighty-five CRE isolates were collected, among which CRKP was most prevalent (68/85). KPC was the most dominant carbapenemase (60/68) in CRKP, while NDM-type carbapenemase was more prevalent in other species. ST11 was the dominant CRKP clone and was phylogenetically divided into three clusters: ST11-KL64, ST11-KL47 and ST11-KL30. CRKP ST11-KL30 is a novel recombinant clone that harbours a pK2044-like virulence plasmid and can be derived from ST11-KL64 by obtaining an ∼57 kb region from ST29-KL30. Compared to ST11-KL47 and ST11-KL64, ST11-KL30 had lower virulence, but had enhanced biofilm formation. ConclusionsWe describe the prevalence of CRE prevalence southern Xinjiang and report the emergence of a region-specific clone. Our findings underscore the potential dissemination of ST11-KL30, which warrants increased monitoring in the future.

Antimicrobial susceptibility of Clostridium botulinum group III field strains isolated in Europe from animal outbreaks

Neurotoxins produced by Clostridium (C.) botulinum group III are responsible for the majority of botulism outbreaks occurring in animals and in this study we report the drug susceptibility of 71 field strains. The minimum inhibitory concentration (MIC) of 13 antimicrobials was established through the agar dilution method. The MIC50 matched or differed for one or two dilutions from MIC90 of the same antimicrobial, showing a unimodal distribution of the MIC values, irrespective of the geographical origin, the animal source and the toxinotype of the strain. Beta-lactams and rifampin showed the lowest MIC values, while gentamicin, polymyxin B and sulfamethoxazole showed the highest MICs. As for similar studies conducted in human botulism, the results could be helpful to avoid the administration of antimicrobials that could worsen the health condition of the affected animals and to develop selective media for the isolation of these fastidious anaerobes. Indeed, the isolation of the strain from affected animals and from environmental samples is important to perform epidemiological studies based on the genetic characterization and to produce tailor-made vaccines.

Characterization of Chlorhexidine Resistance Among Clinical Isolates of Coagulase-Negative Staphylococcus Species in a Tertiary Care Center, Chennai.

Background Coagulase-negativeStaphylococci(CoNS) are potential pathogens and are often associated with healthcare-associated infections (HAIs). Chlorhexidine (CHX) is the most widely used antiseptic to reduce colonization and infection by allStaphylococci, including CoNS. Resistance to CHXamong CoNS has been observed over the past few years, consequent to its widespread use. Phenotypic tolerance or reduced susceptibility to CHX is conferred by plasmid-mediatedqacgroup of genes, mainlyqacA/Bandsmr, which cause activation of efflux pumps over the bacterial cell wall. This study aims to characterize the phenotypic and genotypic resistance exhibited by CoNS species against CHX. Methods After ethical approval, 148 consecutive, non-repetitive isolates of clinically significant CoNS species of hospitalized patients, isolated from blood samples and exudative specimens, were included in the study. Speciation was performed by conventional biochemical identification and automated methods. Antimicrobial susceptibility testing was performed by disc diffusion technique and for vancomycin by minimum inhibitory concentration (MIC) determination, as per Clinical Laboratory Standards Institute (CLSI) M-100 2023 guidelines. Methicillin resistance was detected using a cefoxitin disc. MIC for CHX was performed by agar dilution method; reduced susceptibility was considered when MIC to CHX ≥4 µg/mL. The simplex polymerase chain reaction (PCR) was carried out with suitable controls to detectqacA/Bandsmr. Statistical analysis was conducted to determine the association ofqacA/Bandsmrgenes with MIC of CHXin the study isolates. Results Fifteen different species of CoNS were obtained from clinical samples. A high percentage of resistance was observed against various classes of antibiotics. Methicillin resistance was observed in 69.6% (103/148) of isolates. Of 148 CoNS, 52.7% (78/148) of isolates exhibited reduced susceptibility to CHX with an MIC ≥4 µg/mL. These isolates exhibited a higher percentage of methicillin resistance (75.6%, 59/78). By PCR, 34.5% (51/148) of isolates carried either or both genes. GeneqacA/Bwas solely detected in 27.02% (40/148) of isolates, of which 14 were CHX-tolerant and the remaining 26 were CHX-susceptible. Genesmrwas solely detected in 4.1% (6/148) of isolates comprising three isolates each in CHX-tolerant and susceptible categories.There were 3.4% (5/148) of isolates that harbored bothgenes, of which only one isolate was CHX-susceptible, while the other four were CHX-tolerant. A proportion of isolates that were phenotypically tolerant to CHX did not carry either or both genes. A significant statistical association was found between reduced susceptibility to CHX and the presence of antiseptic resistance genesin the study isolates (p-value=0.033942). Conclusion To our knowledge, this is the first study from South India to investigate CHX resistance among CoNS using phenotypic and genotypic methods. The rise of antiseptic resistance among CoNS is an emerging threat to current infection control practices. The presence ofqacA/Bandsmrgenes, especially in CHX susceptible isolates, is concerning since these resistance genes are located on transferable plasmids, and the isolates can develop resistance eventually upon exposure to CHX.

Chemical composition and biological activities of essential oils from Alyssoides utriculata (L.) Medik

The chemical compositions, antioxidant activities, and antimicrobial activities of the essential oils acquired from the separated parts of air-dried flowers, leaves, and stems of Alyssoides utriculata L. plant growing in Turkiye were determined. Three volatile oil components were acquired via hydrodistillation using a Clevenger apparatus and analyzed by the Gas Chromatography-Mass spectrometry/Flame Ionization Detection (GC-MS/FID) analysis. A total of 75, 67, and 76 compounds in the volatile oils of flower, leaves, and stem of A. utriculata were identified, respectively. The highest percentage of chemical compounds in the essential oils of A. utriculata were determined to be monoterpenes in flowers and leaves, (72.4% and 66.5%) and hydrocarbons (29.2%) in stems. While α-pinene (62.5% and 46.7%) was defined as the major compound in the flowers and leaves, nonane (21.2%) was determined to be so in the stem essential oil. The antioxidant activity of the obtained essential oils was determined according to free radical scavenging and total phenolic content (TPC), and antimicrobial activity against 12 bacteria and 5 fungi, using the agar dilution method. The amount of TPC and scavenging activity of the flower oil were found to be 440.61 ± 6.26 mg GAE/L and 46.00 ± 1.28%, respectively. Based on the antimicrobial activity results, all the essential oils of A. utriculata were determined to have antimicrobial activity against Escherichia coli and Bacillus subtilis.

Evaluation of the Disk Diffusion Test for Bacteroides fragilis Group Clinical Isolates.

Bacteroides fragilis group (BFG) isolates are the most frequently isolated gram-negative anaerobic bacteria and exhibit higher levels of antimicrobial resistance than other anaerobic bacteria. Reliable susceptibility testing is needed because of reports of resistance to the most active antibiotics. Recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) introduced disk zone diameter breakpoints. We evaluated the disk diffusion test (DDT) for susceptibility testing of BFG isolates compared with the agar dilution method. In total, 150 BFG isolates were collected from three institutes in Korea. The agar dilution method was conducted according to the CLSI guidelines. DDT was performed following the EUCAST guideline. Fastidious anaerobe agar supplemented with 5% defibrinated horse blood was used as the culture medium. Nine antimicrobials were evaluated: penicillin, cefoxitin, cefotetan, imipenem, meropenem, piperacillin-tazobactam, clindamycin, moxifloxacin, and metronidazole. The categorical agreement (CA) between the two methods was >90.0% for imipenem, meropenem, clindamycin, and metronidazole. However, the CA for piperacillintazobactam was low, at 83.2%. Major errors were found: 5.4% for imipenem, 7.4% for meropenem, and 12.8% for piperacillin-tazobactam. All minor errors were <10%. We propose using the area of technical uncertainty (ATU) zone-overlapping area for susceptible and resistant strains to reduce errors in the DDT. Outside the ATU, the CAs of cefoxitin, cefotetan, and piperacillin-tazobactam were >90.0%, whereas that of moxifloxacin was increased to 88.5%. The DDT can be a useful alternative antimicrobial susceptibility test for BFG isolates when using the ATU zone to reduce errors.

Presence of multiple van genes among glycopeptide non-susceptible Staphylococcus aureus exhibiting in vitro MIC creep phenomenon: A study from north-east India.

Background & objectives The global prevalence of vancomycin-resistant Staphylococcus aureus (VRSA) has increased two fold since 2010, accounting for 2.4 per cent of S. aureus infections. The emerging hVISA isolates and their increasing trends pose a serious therapeutic challenge. The present study investigated in vitro vancomycin and teicoplanin minimum inhibitory concentration (MIC) creep in S. aureus and assessed their revertants. Methods A total of 845 isolates were collected for this study, and 246 were confirmed as S. aureus. Molecular characterization of vancomycin resistance was carried out by PCR assay targeting genes types viz: vanA, vanB, vanC, vanC2/C3, vanD, vanE, and vanG. MIC was determined for vancomycin and teicoplanin by agar dilution method. MIC creep and revertant analysis were done by broth dilution method in the presence and absence of antibiotics. Results PCR assay confirmed 12 isolates were harboured vanA, followed by vanD (n=8) and vanB (n=7). The study showed 69 isolates were screened positive for glycopeptide non-susceptibility. While analyzing vancomycin MIC creep, four isolates showed a significant increase in MIC, whereas no creep phenomenon was observed for the rest. In the case of teicoplanin, seven isolates showed the MIC creep phenomenon. Revertant analysis of all the isolates that showed MIC creep phenomenon for vancomycin and teicoplanin reverted to their original MIC when the antibiotic pressure was withdrawn. Interpretation & conclusions In the present study setting, glycopeptide non-susceptibility was found in eight per cent of the isolates, and the present study found the occurrence of multiple van genes from isolates calculated from a single study center will impose a serious challenge in infection control and antibiotic policy. This study also underscores that heterogenic resistant isolates, upon exposure to vancomycin and teicoplanin at a minimum level, exhibited an increase in MIC, which will impact individuals receiving glycopeptide therapy.

Multicentre evaluation of in vitro activity of contezolid against drug-resistant Staphylococcus and Enterococcus.

To investigate susceptibility to contezolid, a novel oxazolidinone, multicentre surveillance was conducted involving 2449 strains of Staphylococcus and Enterococcus collected from 65 hospitals across China. The MICs of contezolid, linezolid and other clinically significant antibiotics were determined by the broth microdilution method. Consistency with the broth microdilution method for contezolid was assessed using agar dilution method, as well as disc diffusion and ETEST for linezolid, respectively. WGS was conducted on all 20 linezolid-resistant and 30 randomly non-resistant strains to analyse linezolid resistance genes (optrA, poxtA, cfr) and 23S rRNA mutation sites. All strains exhibited WT susceptibility to contezolid, while resistance proportions to daptomycin, vancomycin, teicoplanin, tigecycline and eravacycline ranged from 0% to 5.2% in Staphylococcus, and from 0% to 7.8% in Enterococcus. Linezolid resistance was higher in Enterococcus faecalis (4.4%) compared with Enterococcus faecium (0.2%). Contezolid showed a lower MIC50 (0.5 mg/L) than linezolid (2 mg/L) for methicillin-resistant Staphylococcus. Against Enterococcus, contezolid demonstrated a cumulative MIC percentage of 70% for VRE and 39.1% for E. faecalis (at MIC = 1 mg/L), whereas linezolid showed 0% and 1.1%, respectively. Among the 20 linezolid-resistant Enterococcus strains, all carried the optrA gene without 23S rRNA mutations. For contezolid, MICs were 4 mg/L for 19 strains and 2 mg/L for 1 strain. The ETEST, agar dilution and disc diffusion methods showed essential and categorical agreements of >90% for linezolid, with no major errors or very major errors. Contezolid demonstrated significant in vitro antibacterial activity against methicillin-resistant Staphylococcus, VRE and linezolid-resistant E. faecalis.

Analysis of Eremostachys hyoscyamoides essential oil composition and assessing the antibacterial and antioxidant properties of the ethanol extract

The increasing issue of antibiotic resistance in bacterial infections has led to challenging and costly treatments. Free radicals significantly contribute to the progression of several diseases, such as cardiometabolic disorders, neurodegenerative conditions, and cancers. Antioxidants can help alleviate or prevent these health problems. This research aimed to assess the antibacterial and antioxidant effects of Eremostachys hyoscyamoides ethanol extract. Additionally, the chemical profile of the essential oil obtained from the aerial parts of E. hyoscyamoides was characterized through gas chromatography-mass spectrometry (GC-MS). The extract's antibacterial effect was tested against three Gram-positive bacteria (Micrococcus luteus, Staphylococcus epidermidis, and S. aureus), in addition to three Gram-negative bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli). The cup-plate method was employed to assess the antibacterial activity, which was subsequently followed by the determination of the minimum inhibitory concentration through the agar dilution method. To evaluate the antioxidant effects, the DPPH radical scavenging assay was used. The total phenolic content (TPC) and flavonoid content (TFC) of the extract were quantified using the Folin Ciocalteu and Aluminum Chloride methods as spectrophotometric-based techniques, respectively. The essential oil of E. hyoscyamoides was extracted via hydrodistillation and subjected to GC-MS analysis. The findings demonstrated that the ethanol extract of E. hyoscyamoides effectively inhibited the growth of the bacterial strains examined. The IC50 value measured in the DPPH test was 48.194 ± 0.61 μg/mL. The TPC was found to be 84.15 ± 2.5 mg GAE/g, while the TFC was determined to be 19.35 ± 1.3 mg RE/g. A total of 50 components, accounting for 93.6 % of the essential oil composition, were identified. High concentrations of elemol (6.8 %), 2,4-di-tert-butylphenol (10.7 %), and linalyl acetate (4.2 %) were putatively identified in the essential oil. In conclusion, the ethanol extract of E. hyoscyamoides exhibited hopeful potential as a natural source of antioxidants and antibacterial agents.

Neisseria gonorrhoeae treatment failure to the recommended antibiotic regimen-Québec, Canada, 2015-19.

To describe Neisseria gonorrhoeae treatment failure to the recommended antimicrobial regimens (azithromycin, cefixime and ceftriaxone). Our study was a longitudinal analysis of treatment failures from an observational open cohort of gonococcal infection cases collected in Québec, Canada (n = 2547) between September 2015 and December 2019. Epidemiological and clinical data were collected using a self-administered questionnaire, direct case interviews and chart reviews. Antimicrobial susceptibility testing was performed using the agar dilution method. To be retained as a treatment failure, cases must have had (i) a laboratory-confirmed gonococcal infection; (ii) a documented treatment; (iii) a positive test of cure (TOC) performed within a defined period and (iv) no sexual contact (vaginal, oral or anal), even protected with a condom, between the beginning of treatment and the positive TOC. A broader definition, including suspected cases, was also examined. Among 1593 cases where a TOC was performed, 83 had a positive TOC: 11 were retained as treatment failure, and 6 were considered suspected cases (overall = 17/1593; 1.1%). Possible explanations for retained or suspected treatment failure included resistance to the antibiotics used for treatment (n = 1), pharyngeal infection (n = 9, of which 5 had been treated with ceftriaxone and 4 with other regimens); and azithromycin monotherapy (n = 1). Some cases had more than one potential explanation. Treatment failure occurred in 1.1% of cases of Neisseria gonorrhoeae infection for which a TOC was performed, including some cases of pharyngeal infection treated with ceftriaxone.

Evaluation of the Antimicrobial Activity of Triple Enzyme-Embedded Organic-Inorganic Hybrid Nanoflowers (hNFs) in Comparison with Powerful Antimicrobial Agent Chitosan.

Organic-inorganic hybrid nanoflowers (hNFs) have high stability, reusability, low production cost, and overcome substrate/product inhibition. Antimicrobial activity of various hNFs has been reported to overcome environmental microbial contaminations and infections, which are considered major public health problems. α-amylase, protease, and lipase are the most common industrial enzymes exerting antimicrobial activity; therefore, we synthesized triple enzyme (α-amylase, protease, and lipase)-embedded hNFs by using pancreatin to evaluate their antimicrobial activity in comparison with one of the most potent antimicrobial polymer chitosan. The broad spectrum of the antimicrobial properties of chitosan is used in industrial products, including cosmetics, food, agriculture, pharmaceuticals, and textiles. SEM analysis, thermogravimetric analysis (TGA), and the degree of deacetylation (%DD) were performed for chitosan characterization, where SEM, FTIR, EDX, and XRD analyses were performed for the characterization of hNFs. The catalytic activity of pancreatin and hNFs was evaluated by measuring lipase, α-amylase, and protease enzyme activities at 37°C. Antibacterial activities of hNFs, pancreatin, and chitosan were tested on gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, compared to the pancreatin and chitosan via agar and broth dilution methods. hNFs showed enhanced catalytic activity for protease, lipase, and α-amylase compared to pancreatin at different pH values (pH 8, 9). hNFs showed catalytic activity after being washed and reused up to six times, indicating their reusability and recoverability. hNFs showed significant antimicrobial activity, such as chitosan, Staphylococcus aureus, and Escherichia coli, compared to pancreatin. Our novel hNFs can be used to develop antimicrobial technologies to fight against environmental microbial contaminations and antibiotic resistance-driven environmental pathogens.

Phytochemical, antioxidant and antibacterial studies of extracts and chromatographic fractions of &lt;i&gt;Gmelina arborea&lt;/i&gt; Roxb (Lamiaceae)

Antimicrobial resistance and oxidative stress are increasing and researchers are being encouraged to search the natural plant products, due to their popular usage in ethno-medicine, for alternative source of antimicrobial and antioxidant compounds. Gmelina arborea used in West-Africa and Ayurveda folkloric medicine to cure several diseases was therefore investigated for phytochemical, antioxidant and antimicrobial activities. Extracts and chromatographic fractions of the root-bark tested for antibacterial activity with the MIC determined on seven selected bacteria using agar dilution method. The antioxidant capacity of the crude extracts was determined by six (6) methods: total flavonoid content, total phenolic content, ferric reducing power, total antioxidant capacity, Trolox equivalent antioxidant capacity and DPPH (2,2-diphenyl-1-picryhydrazyl) properties. Phytochemical screening indicated the presence of saponins, tannins, flavonoids, terpenoids anthraquinones, phenols and alkaloids. The methanol and ethyl-acetate extracts of the plant showed good antibacterial activities (18 mm inhibitory zones and MIC and MBC 12.5–100 mg/mL) against P. aeruginosa ATCC 27853 and S. aureus ATCC 6571. Antioxidant study of the extracts revealed that both ethyl acetate and methanol extracts have good antioxidant capacity comparable to that of ascorbic acid standard. Therefore, Gmelina arborea could prove a valuable source of developing new antimicrobial and antioxidant compounds for therapeutic uses.