Agar Dilution Method Research Articles

Can fosfomycin be an alternative therapy for infections caused by E. coli harbouring dual resistance: NDM and four-amino acid insertion in PBP3?

NDM-expressing Escherichia coli infections are challenging to treat, due to limited treatment options. E. coli with four-amino acid inserts (YRIN/YRIK) are also common in India and it has been reported to reduce the susceptibility to aztreonam/avibactam and the clinically used triple combination ceftazidime/avibactam with aztreonam. Thus, there is a severe dearth of antibiotics to treat infections of NDM + PBP3 insert E. coli. In this study, we determined the susceptibility of E. coli with NDM and PBP3 insert to fosfomycin as an alternative option to treat serious infections. Non-duplicate well-characterized NDM-expressing (without or with co-expression of OXA-48-like) E. coli isolates (n = 213) subsequently carrying four-amino acid inserts in PBP3 were included in this study. MICs of fosfomycin were determined by the agar dilution method with glucose-6-phosphate supplementation, while for other comparators the broth microdilution method was used. Collectively, 98% of NDM-expressing E. coli isolates with PBP3 insert were susceptible to fosfomycin at the MIC of ≤32 mg/L. Resistance to aztreonam was noticed in 38% of the tested isolates. Putting together fosfomycin's in vitro activity, clinical efficacy and safety in randomized controlled trials, we conclude that fosfomycin could be considered as an alternative option to treat infections caused by E. coli harbouring NDM and PBP3 insert resistance mechanisms.

Evaluation of Neisseria gonorrhoeae Isolates Susceptibility to Antibiotics in Zhejiang Province Since 2007.

This study aimed to assess the drug susceptibility of clinical isolates of Neisseria gonorrhoeae to spectinomycin, ceftriaxone and azithromycin. Moreover, the temporal trends in the minimum inhibitory concentration (MIC) of five antibiotics from Zhejiang, China, are also in the scope of this study. A total of 1710 gonococcal clinical strains were collected between 2007 and 2021 from health-care institutions in Zhejiang. The MICs of ceftriaxone, azithromycin, spectinomycin, penicillin and ciprofloxacin were assessed by agar dilution method on 1710 Neisseria gonorrhoeae isolates. Count data were expressed as strains and rates, and MICs distribution was elucidated using descriptive statistics. The total resistance rates of gonococci to azithromycin, spectinomycin, penicillin and ciprofloxacin in this study were 19.3%, 0.3%, 75.4% and 99.7%, respectively. The in vitro results showed a high prevalence of resistance to ciprofloxacin and penicillin. Azithromycin resistance rate has exceeded 5%, suggested a high prevalence of resistance. Ceftriaxone and spectinomycin are suggested based on this study for the treatment of Neisseria gonorrhoeae in Zhejiang.

Antibiotic Sensitivity Pattern of Carbapenem-Resistant Pseudomonas Aeruginosa

Objective: To determine the sensitivity of Carbapenem-resistant Pseudomonas aeruginosa (CARP) with the panel of antibiotics according to Clinical and Laboratory Standards Institute (CLSI) 2020 guidelines.
 Study Design: Cross-sectional study.
 Duration and Place of Study: Armed Forces Institute of Pathology, Rawalpindi from Pakistan, Apr to Sep 2020.
 Methodology: All samples received at the Microbiology Department during the study period were included. Various samples such as blood, pus, sputum, Endobronchial washing (EBW), non-directed bronchial lavage (NBL), tissue and urine were processed in the laboratory. Samples were inoculated on appropriate culture media, and bacteria were identified according to their colony morphology, Gram staining characteristics and biochemical tests. Antibiotic susceptibility testing was performed using the Kirby Bauer Disk Diffusion technique according to Clinical and Laboratory Standards Institute (CLSI) 2020 guidelines. However, for susceptibility to Colistin, the agar dilution method was performed.
 Results: In our study, fifty-five Carbapenem-resistant Pseudomonas aeruginosa were isolated. Out of these fifty-five isolates,thirteen (23.6%) were sensitive to Tazocin, seven (12.7%) were sensitive to Ceftazidime, fourteen (25.4%) were sensitive to Gentamicin, 7(12.7%) were sensitive to Cefepime, (12.7%) to Aztreonam, 10(18.2%) were sensitive to Amikacin, 7(12.7%) to Ciprofloxacin, 6(11%) to Levofloxacin and forty-two (76.4%) were sensitive to Colistin.
 Conclusion: The susceptibility of Carbapenem-resistant Pseudomonas aeruginosa to all the antibiotics tested in this study was low. Isolates displayed the highest susceptibility to Colistin.Keywords: Antibiotic susceptibility profile, Carbapenems, Carbapenem-resistant Pseudomonas aeruginosa (CRPA), Disk diffusion technique.

Development and evaluation of a simple PCR assay and nested PCR for rapid detection of clarithromycin-resistant Helicobacter pylori from culture and directly from the biopsy samples in India

BackgroundEradication of Helicobacter pylori provides the most effective treatment for gastroduodenal diseases caused by H. pylori infection. Clarithromycin, a member of the macrolide family, still remains the most important antibiotic used in H. pylori eradication treatment. But the increasing prevalence of clarithromycin resistant H. pylori strains due to point mutations in the V region of the 23S rRNA, poses a great threat in treating the ailing patients. So, we aimed for PCR-mediated rapid detection of the point mutation at 2143 position of 23S rRNA gene in H. pylori that is relevant to clarithromycin resistance from culture and simultaneously from biopsy specimens to avoid the empirical treatment.ResultsNewly developed PCR assay using DNA of pure culture detected point mutation in 23S rRNA gene in 21 (8.04%) of 261 clinical strains tested. The agar dilution method showed that all these 21 strains were resistant to clarithromycin indicating the perfect match of the PCR based results. Additionally, the sequencing study also identified the A to G mutation at 2143 position in 23S rRNA gene of the resistant strains only. Consequently, the newly developed Nested-ASP-PCR dealing directly with 50 biopsy specimens demonstrated 100% sensitivity and specificity with the findings of agar dilution method taken as Gold standard. Bioinformatics based analysis such as accessibility analysis and dot plot clearly stated that the base pairing probability has increased due to mutation. Computational studies revealed that the point mutation confers more stability in secondary structure due to conversion of loop to stem. Furthermore, interaction studies showed binding affinity of the CLR to the mutant type is weaker than that to the wild type.ConclusionThis assay outlines a rapid, sensitive and simple approach to identify point mutation that confers clarithromycin resistance as well as clarithromycin sensitive strains, providing rapid initiation of effective antibiotic treatment. Additionally, it is simple to adopt for hospital based diagnostic laboratories to evaluate the degree of regional clarithromycin resistance from biopsy specimens itself. Furthermore, in silico studies provide evidence or a signal that the prevalence of clarithromycin resistance may rise in the near future as a result of this point mutation.

A Novel CMY Variant Confers Transferable High-Level Resistance to Ceftazidime-Avibactam in Multidrug-Resistant Escherichia coli.

Here, our objective was to explore the molecular mechanism underlying ceftazidime-avibactam resistance in a novel CMY-178 variant produced by the clinical Escherichia coli strain AR13438. The antibiotic susceptibility of the clinical isolate, its transconjugants, and its transformants harboring transferable blaCMY were determined by the agar dilution method. S1-PFGE, cloning experiments, and whole-genome sequencing (WGS) were performed to investigate the molecular characteristics of ceftazidime-avibactam resistance genes. Kinetic parameters were compared among the purified CMY variants. Structural modeling and molecular docking were performed to assess the affinity between the CMYs and drugs. The horizontal transferability of the plasmid was evaluated by a conjugation experiment. The fitness cost of the plasmid was analyzed by determining the maximal growth rate, the maximum optical density at 600 nm (OD600), and the duration of the lag phase. AR13438, a sequence type 457 E. coli strain, was resistant to multiple cephalosporins, piperacillin-tazobactam, and ceftazidime-avibactam at high levels and was susceptible to carbapenems. WGS and cloning experiments indicated that a novel CMY gene, blaCMY-178, was responsible for ceftazidime-avibactam resistance. Compared with the closely related CMY-172, CMY-178 had a nonsynonymous amino acid substitution at position 70 (Asn70Thr). CMY-178 increased the MICs of multiple cephalosporins and ceftazidime-avibactam compared with CMY-172. The kinetic constant Ki values of CMY-172 and CMY-178 against tazobactam were 2.12 ± 0.34 and 2.49 ± 0.51 μM, respectively. Structural modeling and molecular docking indicated a narrowing of the CMY-178 ligand-binding pocket and its entrance and a stronger positive charge at the pocket entrance compared with those observed with CMY-172. blaCMY-178 was located in a 96.9-kb IncI1-type plasmid, designated pAR13438_2, which exhibited high transfer frequency without a significant fitness cost. In conclusion, CMY-178 is a novel CMY variant that mediates high-level resistance to ceftazidime-avibactam by enhancing the ability to hydrolyze ceftazidime and reducing the affinity for avibactam. Notably, blaCMY-178 could be transferred horizontally at high frequency without fitness costs. IMPORTANCE Ceftazidime-avibactam is a novel β-lactam-β-lactamase inhibitor (BLBLI) combination with powerful activity against Enterobacterales isolates producing AmpC, such as CMY-like cephalosporinase. However, in recent years, CMY variants have been reported to confer ceftazidime-avibactam resistance. We reported a novel CMY variant, CMY-178, that confers high-level ceftazidime-avibactam resistance with potent transferability. Therefore, this resistance gene is a tremendous potential menace to public health and needs attention of clinicians.

The linkage between prevalence of integron I and reduced susceptibility to biocides in MDR Klebsiella pneumoniae isolated from neonates.

Klebsiella pneumoniae causes challenging nosocomial fatal infections including neonatal sepsis. Our study aims at clarifying the contribution of integrons in the observed reduced susceptibility of multidrug-resistant (MDR) K. pneumoniae isolated from septicemic neonates to the clinically used antimicrobial agents and biocides. Eighty-six K. pneumoniae isolates were collected from Mansoura University Children's Hospital from septicemic neonates. Isolates were subjected to antibiotic and biocide susceptibility using disk diffusion and the agar dilution method, respectively. The distribution of different classes of integrons was screened in the isolates by PCR. Detected inegron I was sequenced in selected isolates. Fifty-seven isolates (66.27%) were MDR. In the MDR isolates, class I integron was detected in 23 (40.3%), integron III was detected in 20 (35%), whereas integron II could not be detected. Sequencing results of integron I from MDR K. pneumoniae isolates revealed that only aminoglycoside and folate synthesis inhibitors gene cassettes were detected, while the rest of the resistance genes were not associated with integron I. The presence of integron I in MDR K. pneumoniae tested isolates may contribute only to some biocide resistance, however, it does not seem to be the only contributor in multiple drug resistance.

Evaluation of Piperacillin/Sulbactam, Piperacillin/Tazobactam and Cefoperazone/Sulbactam Dosages in Gram-Negative Bacterial Bloodstream Infections by Monte Carlo Simulation.

The optimal regimens of piperacillin/sulbactam (PIS 2:1), piperacillin/tazobactam (PTZ 8:1), and cefoperazone/sulbactam (CSL 2:1) are not well defined in patients based on renal function. This study was conducted to identify optimal regimens of BLBLIs in these patients. The antimicrobial sensitivity test was performed by a two-fold agar dilution method. Monte Carlo simulation (MCS) was used to simulate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) for various dosing regimens in patients with different renal functions. For strains with an MIC ≤ 8/4 mg/L, PIS 4.5 g q6h achieved 99.03%PTA in the subset of patients with creatinine clearance (CrCL) > 90 mL/min. For patients with CrCL 60-90 mL/min, PIS 4.5 g q6h achieved 81.2% CFR; for those with CrCL 40-59 mL/min, PIS 4.5 g q8h achieved 80.25% CFR. However, for patients infected by ESBL-producing Enterobacteriaceae, PIS 4.5 g q6h achieved a CFR lower than 80%. For patients infected by A. baumannii with a CrCL of 31-60 mL/min, PIS 6.0 g q8h and 4.5 g q6h achieved 81.24% and 82.42% CFR, respectively. For those infected by P. aeruginosa, PIS 4.5 g q6h reached 90% CFR. PIS and PTZ achieved a similar CFR when piperacillin was at the same dose. The CFRs of CSL were much lower than those of the other two agents in Enterobacteriaceae and P. aeruginosa infections. The antibacterial spectrum of PIS is superior to that of PTZ and CSL. Higher dosages and dosing adjustment according to renal function should be considered to treat Gram-negative bacterial BSIs.

Antibiotic resistance of probiotics isolated from Chinese corn stover silage

ABSTRACT One of the most important drivers of the emergence of antimicrobial resistance is the irrational usage of antibiotics. But alongside some indirect sources such as feeding Chinese corn stover silage could also transmit resistant genes to animals. This study was aimed at assessing the antibiotic resistance phenotypes, drug resistance genes and mediated drug resistance mechanisms. A total of 37 isolates were obtained by selective medium and identified by 16S rDNA sequencing including Lactobacillus acidophilus (n = 3), Lactobacillus amylovorus (n = 4), Weissella confusa (n = 3), Acetobacter pasteurianus (n = 9), Lactobacillus buchneri (n = 6), Enterococcus faecium (n = 8) and Lactobacillus reuteri (n = 4). Antimicrobial resistance of all isolates to 12 antibiotics was determined using the agar dilution method. Widespread resistance to ampicillin, erythromycin, clindamycin, kanamycin, streptomycin, levofloxacin and ciprofloxacin was observed. The presence of relevant resistance genes was examined by PCR, and the genes pbp5, blaZ, bla TEM, mecA, mexI, tetW, ermB, msrA, msrC, ermC, vatE, aacA-aphD, aphA1, aadA1, aadA2 and vanX were detected. All the isolated strains had multiple drug resistance, and harboured related drug-resistant genes; therefore, the use of probiotics in animal feed should be standardized to reduce the risks of horizontal transmission of drug resistance genes to animal products and human population. Highlights Fermentation bacteria isolated from the silage were identified. Lactobacillus strains isolated from the silage exhibited antimicrobial resistance. Feeding Chinese corn stover silage transmits resistant genes to animals. Standardization of probiotics in animal feed is crucial to avoid horizontal drug resistance.

Staphylococcus aureus in Horses in Nigeria: Occurrence, Antimicrobial, Methicillin and Heavy Metal Resistance and Virulence Potentials

Staphylococcus aureus was isolated from a total of 360 nasal and groin skin swabs from 180 systematic randomly-selected horses slaughtered for meat at Obollo-Afor, Enugu State, Southeast Nigeria and antimicrobial, methicillin and heavy metal resistance profile and virulence potentials of the isolates established. Baird-Parker agar with egg yolk tellurite was used for S. aureus isolation. S. aureus isolates were confirmed biochemically and serologically using a specific S. aureus Staphytect Plus™ latex agglutination test kit. The antimicrobial resistance profile, methicillin, vancomycin and inducible clindamycin resistance, and β-lactamase production of the isolates were determined with disc diffusion. Tolerance to Copper, Cadmium, Lead and Zinc was assessed using the agar dilution method and virulence potentials were determined using phenotypic methods. Forty-three (23.9%) of the 180 horses harbored S. aureus. Some 71 S. aureus were recovered from the 360 samples. Two (2.8%) of the 71 S. aureus were methicillin-resistant S. aureus (MRSA) and 69 (97.2%) were methicillin-susceptible. MRSA was recovered from 2 (1.1%) of the 180 horses. Some 9.4% of the isolates were multiple drug-resistant (MDR). The mean multiple antibiotic resistance indices (MARI) for the isolates was 0.24. Heavy metal resistance rate of the isolates ranged between 35.4-70.4%. The isolates, including the MRSA strains, displayed virulence potentials as clumping factor and catalase, gelatinase, caseinase, heamolysin, and biofilm was at the rate of 100%, 53.5%, 43.7%, 18.3% and 23.9%, respectively. This study showed that a considerable percentage of horses slaughtered in Obollo-Afor Southeastern Nigeria are potential reservoirs of virulent multiple drug- and heavy metal-resistant S. aureus, including MRSA, that could spread to humans and the environment.

Synthesis and computational studies of novel cobalt(II) and oxovanadium(IV) complexes of quinoline carbaldehyde derivative ligand for antibacterial and antioxidant applications

Novel metal complexes [Co(HL)2(H2O)2)] (1) and [VO(HL)2] (2) were synthesized using 2-((2-hydroxyethyl)amino)quinoline-3-carbaldehyde, ligand in 1:2 metal–ligand ratio in methanolic solution. The compounds were characterized with 1HNMR, 13CNMR, UV–Visible spectroscopy, fluorescence spectroscopy, FTIR Spectroscopy; powder X-Ray Diffraction, Scanning Electron Microscopy – Energy Dispersive X-Ray Spectroscopy, Mass Spectroscopy and thermogravimetric analysis. The FTIR spectral data showed that the ligand is bidentate that bound to metal ions through the nitrogen of amine (NH) and the deprotonated hydroxyl group (OH). The powder XRD and SEM results indicate that both the complexes showed polycrystalline nature. The formation constants of the complexes were determined spectroscopically and the values are 2.05 × 106 and 6.29 × 105 for Co(II) and V(IV) complexes respectively). Both metal complexes are stable at the specified temperatures, and the thermodynamic parameters indicated that the reactions are spontaneous with exothermic nature of metal-ligand interactions. Antibacterial activities of the complexes were evaluated with disk diffusion and agar dilution method. The Co(II) complex showed recognizable bacterial activity, against Pseudomonas aeruginosa with mean inhibition zone of 20.65 ± 0.18, with minimum inhibitory concentration (MIC) values of 3.25 µg/mL. Additionally, the antioxidant activity of the complexes were also determined in vitro using 1,1-diphenyl-2-picryl hydrazyl, in which Co(II) complex showed higher antioxidant activities with half maximal inhibitory concentrations IC50 of 9.15 µg/ml. The results of binding mode of these compounds against receptors Escherichia coli, Pseudomonas aeruginosa and Streptococcus pyogenes were in good agreement with the in vitro biological activity results.

Influence of harvest season on the chemical composition and antifungal activity of Citrus limon essential oil

The use of Essential Oil (EO) as an antimicrobial agent has been widely used since antiquity, and interest has grown due to the resistance of microorganisms to drugs. This study aims to evaluate the chemical composition of Algerian Citrus limon peel EO and its antifungal activity against dermatophyte strains, according to the harvest period. EO from C. limon peel harvested during four different periods (Winter, Spring, Summer, and Autumn) was extracted by hydrodistillation Clevenger type and analyzed by GC/MS. Antifungal activity was evaluated against four dermatophyte strains (Trichophyton rubrum, Microsporum canis, Trichophyton mentagrophytes, and Microsporum gypseum) using the disc diffusion and agar dilution methods. The yield of EO from C. limon peel varied from 1.54 to 2.43% (w/w), the highest yield was obtained in Autumn and the lowest in Summer, the EOs were mainly composed of limonene (43.45–58.75%) followed by β-pinene (4.73–13.23%) and γ-terpinene (8.06–11.04%). The assessment of the antifungal activity showed that C. limon peel EO has a strong antifungal activity against the tested strains, with inhibition zones ranging from 16.63 ± 0,38 to 90.00 ± 00 mm, and Minimal Inhibitory Concentration (MIC) from 0.6 to 5 mg/mL and Minimal Fungicidal Concentration (MFC) from 1.25 to 10 mg/mL. Spring harvest EO was relatively more effective in terms of MIC (0.6–2.5 mg/mL) and MFC (1.25–2.5 mg/mL). The EO of C. limon peel showed a seasonal change in the chemical composition and the antifungal activity, also revealed a high antifungal potential, and can be used for the treatment of fungal infections caused by dermatophytes.

Comparison of Disk Diffusion and Agar Dilution Method for the Detection of Mupirocin Resistance in Staphylococcal Isolates from Skin and Soft Tissue Infections.

Aims and Objectives Mupirocin is a widely used topical antibiotic for the treatment of skin and soft tissue infections. This has resulted in resistance leading to treatment failure. Hence, the present study aimed to determine the prevalence of mupirocin resistance among staphylococcal isolates obtained from the skin and soft tissue infections. Also, comparison of disc diffusion and agar dilution method in detecting mupirocin resistance was done. Materials and Methods This cross-sectional study was conducted in the Department of Microbiology of a tertiary health care center in Karnataka from January to December, 2018. Clinical samples such as wound swabs, tissues, and pus were included in the study. All staphylococcal isolates were screened for mupirocin resistance using 5 µg and 200 µg discs for low-level (MuL) and high-level mupirocin resistance (MuH), respectively. Minimum inhibitory concentration (MIC) was determined using the agar dilution method. Results Out of 100 staphylococcal isolates, 68 were Staphylococcus aureus and 32 were CoNS. MuH was detected in 11 isolates. MuH was more common in CoNS (10/11) compared with S. aureus (1/11). MuL was not found in the study. Discussion In our study, 10 out of 11 mupirocin-resistant isolates were methicillin resistant, which is statistically significant ( p < 0.05). The correlation between results of disc diffusion and MIC were appropriate in this study. Conclusion Judicial prescription of mupirocin after knowing the susceptibility report should become the standard practice. Screening for mupirocin resistance can be done by disc diffusion in resource-limited settings.

Antifungal drug resistance in oral Candida isolates from HIV-infected and healthy individuals and efficacy of chitosan as an alternative antifungal agent

ObjectiveThis study aimed to investigate antifungal resistance in oral Candida isolates and the efficacy of chitosan, a natural polymer, against drug-resistant Candida. DesignOral Candida isolates were collected from HIV-infected and healthy individuals in our previous study (n = 66 isolates/group). The minimum-inhibitory-concentration (MIC) of amphotericin-B and fluconazole was determined by Epsilometer test. Minimal-fungicidal-concentration (MFC) of 3 chitosan derivatives: high-molecular-weight chitosan (HMWC, 150–200 kDa), oligomer (7–9 kDa) and polymer (900–1000 kDa) chitosan, were investigated by agar dilution method. Statistical analysis was performed using Chi-square or Fisher's exact tests as appropriate. ResultsFluconazole-resistant C. albicans were significantly more prevalent in HIV-infected than in healthy individuals (P = 0.02), while amphotericin-B-resistant C. parapsilosis were more common in healthy individuals (P = 0.03). The majority of Candida isolates were killed by HMWC at ≤ 40 mg/ml, as well as by oligomer and polymer chitosan at ≤ 6 mg/ml. Remarkably, chitosan was effective against most antifungal drug-resistant isolates. ConclusionsAntifungal drug resistance was prevalent among oral C. albicans isolates from HIV-infected individuals. Chitosan could serve as a complementary antifungal agent against drug-resistant strains.

Bioactivities and Chemical Compositions of Cinnamomum burmannii Bark Extracts (Lauraceae)

Cinnamomum burmanni has antifungal and antibacterial properties, including alkaloids, tannins, flavonoids, saponins, terpenoids, and essential oil content of cinnamaldehyde, eugenol, and safrole. This study aims to determine the antibacterial properties against Streptococcus mutans and Staphylococcus aureus, antifungal properties against Candida albicans and Candida tropicalis, antioxidant, and flavonoid content of microwave-assisted extraction (MAE) extracts from C. burmanni bark. This study began with the MAE extraction of C. burmanni, followed by qualitative phytochemical tests on the alkaloids, tannins, flavonoids, saponins, and terpenoid groups. Furthermore, using the UV-Vis spectrophotometry method, a quantitative phytochemical test was performed to determine the levels of flavonoids. The 1,1-diphenyl-2-pikrilhidrazil (DPPH) method was used for the antioxidant test, the agar dilution method for the minimum inhibitory concentration (MIC), and the paper disc diffusion method for the width of the inhibitory area (LDH). The positive antifungal control was nystatin, while the antibacterial control was amoxicillin, and both negative controls were 1% dimethyl sulfoxide (DMSO). The antifungal and antibacterial components were found to be 3% n-hexane extract from the bark of C. burmanni, with an inhibitory area width (IAW) of 13.83 mm. The best antioxidant results were the ethanol extract with a very active category IC50 of 8.533 ppm, 5.90%, and the highest ethanol extract containing flavonoid test results.

Antimicrobial Resistance of Seventy Lactic Acid Bacteria Isolated from Commercial Probiotics in Korea.

In this study, lactic acid bacteria were isolated from 21 top-selling probiotic products on Korean market and their antimicrobial resistance were analyzed. A total 152 strains were claimed to be contained in these products and 70 isolates belonging to three genera (Bifidobacterium, Lactobacillus, and Lactococcus) were obtained from these products. RAPD-PCR showed diversity among isolates of the same species except for two isolates of Lacticaibacillus rhamnosus from two different products. The agar dilution method and the broth dilution method produced different MICs for several antimicrobials. With the agar dilution method, five isolates (three isolates of Bifidobacterium animalis subsp. lactis, one isolate of B. breve, one isolate of B. longum) were susceptible to all nine antimicrobials and 15 isolates were multi-drug resistant. With the broth microdilution method, only two isolates (one isolate of B. breve and one isolate of B. longum) were susceptible while 16 isolates were multi-drug resistant. In this study, only two AMR genes were detected: 1) lnu(A) in one isolate of clindamycin-susceptible and lincomycin-resistant Limosilactobacillus reuteri; and 2) tet(W) in one tetracycline-susceptible isolate of B. longum B1-1 and two tetracycline-susceptible isolates and three tetracycline resistant isolates of B. animalis subsp. lactis. Transfer of these two genes via conjugation with a filter mating technique was not observed. These results suggest a need to monitor antimicrobial resistance in newly registered probiotics as well as probiotics with a long history of use.

Genomic Analysis and Antimicrobial Resistance of Campylobacter jejuni Isolated from Diarrheal Patients - Beijing Municipality, China, 2019-2021.

Campylobacter jejuni (C. jejuni) is the leading cause of human bacterial gastroenteritis worldwide and has a major impact on global public health. The objective of the present study was to conduct whole genome sequencing (WGS) to determine the genetic diversity, virulence factors, and determinants of antimicrobial resistance of C. jejuni during a 3-year surveillance period in Beijing, China. A total of 184 clinical isolates were obtained from sentinel hospital surveillance between 2019 and 2021. Antimicrobial susceptibility testing was conducted using the agar dilution method. WGS was employed to characterize the 184 C. jejuni strains. Multilocus sequence typing analysis revealed high genetic diversity among the 184 C. jejuni strains, identifying 71 sequence types (STs) and 19 clonal complexes (CCs). The most prevalent ST was ST760 (6.5%), and the most common CC was CC21 (24.5%), consisting of 11 STs. High resistance rates were observed for ciprofloxacin (76.6%), nalidixic acid (76.1%), and tetracycline (71.2%). A total of 77 C. jejuni isolates (41.8%) exhibited multidrug resistance with 43 resistance patterns. Virulome analysis disclosed the differential distribution of virulence factors related to adherence, colonization, chemotaxis, as well as lipo-oligosaccharide and capsular polysaccharide biosynthesis. Resistome analysis demonstrated widespread resistance to quinolones and tetracycline, but low rates of macrolides resistance. The phylogeny, based on whole genome single nucleotide polymorphisms, indicated a high degree of clonality and grouped the C. jejuni strains into six clades. Closely related isolates that were part of a genetic cluster mostly shared a homogenous clonal complex. The present study emphasizes the rising resistance to quinolones and tetracycline, as well as the virulence potential and diverse genotypes identified among C. jejuni strains isolated from diarrheal patients in Beijing.

A Study on Glycopeptide-Resistant Genotypes among Clinical Isolates of Enterococcus with Van B Phenotype.

Enterococci, although remarked as harmless commensals of the intestinal tract of humans and animals, have become a significant source of infection in hospitalized patients worldwide.The present study aimed to isolate and identify enterococci from clinical samples and to determine the genotypic characteristics of vancomycin-resistant enterococcus isolates. A total of 774 isolates of enterococci from clinical samples were identified to the species level, and their anti-microbial susceptibility pattern was determined by Kirby Bauer Disk Diffusion method and Vitek 2 automated system. Screening for vancomycin resistance was performed by using brain heart infusion agar containing 6 micrograms/ml of vancomycin. The minimum inhibitory concentration (MIC) of vancomycin was determined by the agar dilution method and Epsilometer test (E test). Genotyping was carried out for resistant isolates by multiplex polymerase chain reaction. Thirty (3.88%) isolates were resistant to vancomycin by agar screen method. Five isolates showed intermediate resistance with anMIC of 8-16 micrograms/ml for vancomycin by agar dilution. By the E test, two isolates displayed an MIC of ≥32 micrograms/ml for vancomycin and one isolate showed an MICof ≥32 micrograms/ml for teicoplanin.Van A was the common genotype isolated. The present study reports isolates of Enterococcus faecalis with a susceptible MIC for glycopeptide and the presence of the Van A gene. Heterogeneous resistance among clinical isolates of Enterococcus faecalis was observed in our study. The predominant phenotype and genotype detected among clinical isolates were Van A.

The Review on the Antimicrobial Potential of Maidenhair Fern, Adiantum capillus-veneris L.

Adiantum capillus-veneris L. or Maidenhair fern is a perennial fern that belongs to the family Pteridaceae. It is widespread in temperate and tropical regions with high humidity. A. capillus-veneris has a long history of medicinal use, and recent investigations suggest the presence of many bioactive compounds in this plant. This review debates the antimicrobial potential of Adiantum capillus-veneris in a comprehensive manner that includes data about the antibacterial, antifungal, and antiviral activity. Data regarding the antimicrobial potential of A. capillus-veneris were collected from scientific databases Web of Science, Scopus, PubMed, and Google Scholar. The largest number of reviewed studies were related to the antibacterial activity of extracts made from A. capillus-veneris plant. Mainly, leaves, stems, roots, and rhizomes were tested, while water, methanol, ethanol, ethyl acetate, and hexane were used as solvents. For the testing of antimicrobial susceptibility, standard tests were implemented, such as the disk-diffusion method, agar dilution method, and determination of MIC and MBC values. There are also studies testing the antibiofilm effects of the investigated plant. Our review showed that A. capillus-veneris exhibits large antibacterial potential, with the capacity to inhibit the growth of different bacteria, including multidrug-resistant strains. The antifungal and antiviral activity of the investigated plant was also recorded. This review summarized data regarding the antimicrobial potential of A. capillus-veneris and suggests that future phytochemical investigations of ferns may lead to the discovery of new therapeutic agents.

Genotypically Confirmed Vancomycin-Resistant Staphylococcus aureus With vanB Gene Among Clinical Isolates in Kathmandu.

Methicillin-resistant Staphylococcus aureus, a common bacterial pathogen causes various infections. The acquisition of various antimicrobial-resistant genes in S. aureus has led to the transformation of this bacterium into a superbug. Vancomycin resistance among MRSA isolates is an emerging threat in empirical therapy of various infections. The study was hence aimed to find out the susceptibility status of S. aureus isolates toward vancomycin and detect mecA, vanA, and vanB genes among the isolates. A total of 1245 clinical samples from the participants attending a tertiary care hospital in Kathmandu were processed. S. aureus isolated from the samples were subjected to antibiotic susceptibility patterns using the modified Kirby-Bauer disk diffusion method. Agar dilution method was used to determine the minimum inhibitory concentration of vancomycin. The antibiotic-resistant genes such as mecA, vanA, and vanB among S. aureus isolates were screened by a conventional polymerase chain reaction. Of 1245 samples, 80 S. aureus were identified. Out of which, 47.5% (38/80) were phenotypically confirmed MRSA isolates. mecA gene was detected in 84.2% (32/38) of MRSA isolates. 10.5% (4/38) were confirmed as vancomycin-intermediate S. aureus (VISA) by MIC determination. None of the isolates was positive for the vanA gene; however, 2 isolates were found to possess the vanB gene. The 2 isolates have vancomycin MIC breakpoints of 4 to 8 μg/mL. There might be a spreading of vancomycin resistance among S. aureus, creating serious public health problems. Therefore, measures to limit vancomycin resistance should be considered in healthcare facilities as immediately as possible.

Antibacterial activity of essential oils of Salvia Officinalis growing in Morocco.

The bacterial infections treatment is complicated by antibiotic resistance. In this fact, the need for new therapeutic approaches to control bacterial infections is crucial. Therefore, discovering new antibiotics from medicinal plants, able to kill drug-resistant bacteria, is essential to saving modern medicine. This study was to evaluate the in vitro antibacterial activity of Salvia officinalis essential oil (SoEO) growing in Morocco. The essential oil was extracted by hydro distillation, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by agar dilution method. The essential oil was analyzed by Fourier-transform infrared spectroscopy (FTIR) and fractionated/purified using column chromatography followed by thin-layer chromatography (TLC). The results revealed that SoEO showed higher antimicrobial activity against Enterococcus faecalis and Citrobacter freundii. Fourier-transform infrared spectroscopy (FTIR) analysis, and purification/fractionation of SoEO, indicates that the most polar fraction F6 is the active fraction of SoEO. This finding can be explained by the existence of polar compounds in this fraction including alcohols, and phenols as thymol, eugenol, globulol, and spathulenol. It can be conclude that alcohols and phenols from Salvia officinalis essential oil (SoEO) have promising antibacterial activity. This action can offer a great possibility of the application of SoEO in the treatment of bacterial diseases.