Minimum Inhibitory Concentration Test Research Articles

Efficacy of bacteriophages with Aloe vera extract in formulated cosmetics to combat multidrug-resistant bacteria in skin diseases

Phage therapy offers a promising alternative to antibiotic treatment for combating illnesses caused by multidrug-resistant bacteria. In this study, pathogenic bacteria Staphylococcus aureus and Pseudomonas aeruginosa were isolated from pus and skin infected fluidsusing selective media. These bacterial isolates were biochemically identified as S. aureus and P. aeruginosa with probabilities of 98% and 99%, respectively, through VITEK2 system, and were confirmed as multidrug-resistant based on minimum inhibitory concentration test using colorimetric reagent cards. Lytic phages specific to these isolates were isolated, identified through plaque assays, transmission electron microscopy and classified morphologically according to the new International Committee on Taxonomy of Viruses classification as members of the Straboviridae, Drexlerviridae, and Autographiviridae families. A cosmetic gel formulation combining Aloe vera extract and the phage cocktail was prepared and tested. This gel significantly enhanced phage longevity and reduced bacterial growth by 95.5% compared to the reductions of 90.5% with Aloe Vera extract alone and 45.7% with the basic cosmetic gel. The phage remained effective for 4 to over 12 weeks after being preserved in the cosmetic formula, maintaining populations ranging from 5 × 103 to 25 × 104 PFU/mL in vitro. These findings highlight the potential of phage-based formulations, such as Vena Skin Gel, as innovative biotherapeutic tools for managing skin infections.

Isolation and characterization of a broad-spectrum bacteriophage against multi-drug resistant Escherichia coli from waterfowl field.

Escherichia coli (E. coli) is a significant pathogen responsible for intestinal infections and foodborne diseases. The rise of antibiotic resistance poses a significant challenge to global public health. Traditional antibiotic therapy is becoming increasingly ineffective, highlighting the urgent need for innovative control strategies. This study explores the potential of bacteriophages as a sustainable alternative to traditional antibiotics. From 2021 to 2022, a total of 183 non-repetitive duck source fecal samples were collected from Mianyang City, Sichuan Province, and 126 strains of E. coli were isolated. The minimum inhibitory concentration (MIC) test showed that these strains exhibited high resistance to piperacillin (96.8%), tetracycline (88.9%), and chloramphenicol (86.5%). It is concerning that 93.7% of the isolates are classified as multidrug-resistant (MDR), posing a significant threat to existing treatment options. 20 bacteriophages were isolated from fecal and soil samples, among which 5 bacteriophages were selected for further analysis. Bacteriophage YP6 showed excellent lytic effects on MDR strains, especially strain MY104, as well as representative serotypes O1 (E. coli MY51) and O18 (E. coli MY106). The identification of YP6 as a member of the Myoviridae family was conducted using transmission electron microscopy, and it was found to have an optimal infection factor of 0.1. Bacteriophages exhibit significant thermal and pH stability, maintaining survival at temperatures up to 60 °C and pH ranges of 4 to 10. Whole genome sequencing confirmed that YP6 has a double stranded DNA genome of 139,323 base pairs (bp), and no antibiotic resistance or virulence genes were found, indicating a low possibility of horizontal gene transfer. In addition, YP6 effectively inhibits the formation of E. coli biofilm, which is a key factor in chronic infections. The in vivo experiments using Galleria mellonella (G. mellonella) larvae have shown that it has a significant protective effect against MDR E. coli infection. In summary, bacteriophage YP6 is expected to become a therapeutic agent against MDR E. coli infection due to its broad host range, environmental stability, and biofilm inhibition properties. Future research should optimize bacteriophage preparations, evaluate the safety and efficacy of animal models, and establish clinical application plans in the field of food safety.

Standardization, Characterization and Potential Biological Activity of Ozonized Sunflower Vegetable Oil

Objective: The ozone molecule, composed of three oxygen atoms, possesses high oxidizing power and is widely utilized for various applications, including therapeutic treatments involving the administration of medicinal ozone to combat various diseases. The standardization of ozonized oil is essential to ensure patient safety. The objective of this study was to develop protocols for the standardization and characterization of ozonized oil using analytical techniques such as gas chromatography-mass spectrometry (GC-MS) and to evaluate its biological activity through microbiological and cytotoxic assays. Methods: Standardization and characterization were carried using gas chromatography coupled to mass spectrometry (CG-MS), and microbiological tests including agar diffusion, time-kill and MIC and cytotoxic tests were employed in bacterial cells. Results: The obtained results indicated that after 480 minutes of ozonization in 100 mL of sunflower oil (OG), a significant antimicrobial potential was observed, leading to the formation of ozonides. Antibacterial and antifungal activity assays, conducted using the ‘time kill’ method, agar diffusion, and Minimum Inhibitory Concentration (MIC) tests, demonstrated activity against Staphylococcus aureus, Escherichia coli, Salmonella choleraesuis, Pseudomonas aeruginosa, Candida albicans, Aspergillus brasiliensis, and Malassezia furfur. Conclusion: Results demonstrate the therapeutic potential of the application of ozonized oil in the treatment of topic infectious diseases. In summary, the standardization of the ozonization process of sunflower oil showed to be promising, providing a product exerting antimicrobial activity and therapeutic potential, opening perspectives for its application in various areas of medicine.

Detection and selection of dye-degrading bacteria from surface waters with different degrees of contamination

ABSTRACT Biodegradability and resistance from indigenous bacterial communities to dyes were tested using samples from both polluted and unpolluted surface waters in Buenos Aires. Five dyes were selected for the study: Acid Black 210, Direct Orange 39, Malachite Green, Gentian Violet, and Alizarin Red. Water quality was assessed by measuring chemical oxygen demand, biochemical oxygen demand, and both Escherichia coli and enterococci counts. Biodegradability was tested using a respirometric method, while resistance was assessed by determining the minimum inhibitory concentration (MIC). No bacterial strains capable of degrading the dyes as the sole carbon source were isolated from the respirometric tests. However, from the MIC tests, 28 strains capable of dye discolouration were identified, using nutrient broth as a supplement. Two of them were able to degrade Malachite Green and Acid Black 210 at a concentration of 50 mg L−1 in less than 24 h and with an efficiency greater than 87%. These strains were identified as Aeromonas sp. and Shewanella sp. through MALDI-TOF/MS and 16S rRNA gene sequencing. The determination of biodegradability and resistance can be used to enhance the characterization of watercourses. Furthermore, this methodology provides a means to isolate biodegrading bacteria that could be applied in effluent treatment processes.

Comparison of MIC Test Strip and reference broth microdilution method for amphotericin B and azoles susceptibility testing on wild-type and non-wild-type Aspergillus species.

This study aimed to evaluate whether the MIC Test Strip (MTS) quantitative assay for determining the minimum inhibitory concentration (MIC) correlated with the CLSI reference broth microdilution (BMD) method for antifungal susceptibility testing of wild-type and non-wild-type Aspergillus species against antifungal agents known to be usually effective against Aspergillus spp. This study was performed to assist in the decision-making process for possible deployment of the MTS assay for antimicrobial susceptibility testing of Aspergillus species into regional public health laboratories of Mycology due to difficulties in equipping the reference BMD methods in a laboratory routine. For this purpose, a set of 40 phenotypically diverse isolates (27 wild-type, 9 non-wild-type, and 4 species with reduced susceptibility to azoles and amphotericin B [AMB]) collected from clinical samples were tested. MICs were performed by both MTS and reference BMD for AMB and azoles. MTS results for posaconazole correlated well with reference BMD, rendering an almost perfect agreement (kappa value=1.000) by category interpretation (CI)/category distribution of MICs (CDM) (100%), while voriconazole MTS results yielded a substantial correlation with BMD (kappa value=0.788) by CI/CDM (97.5%). In contrast, itraconazole and AMB yielded the poorest correlation with BMD, rendering moderate agreement (kappa values of 0.554 and 0.437, respectively) by CI/CDM (87.5% and 85%, respectively). In conclusion, the MTS method represents a valid option for antimicrobial susceptibility testing of Aspergillus species against posaconazole and voriconazole. Itraconazole and AMB MTS results showed some concerning lack of correlation with the corresponding reference BMD results.

Phytochemical Screening, Antioxidant and Antibacterial Properties of Alcoholic Extract of Saussurea costus Roots

Background: Diseases in their essence are non-curable and the underlying pathogenesis is bidirectional of inflammation and oxidative stress. Fighting oxidative stress and inflammation should be the target for any first-line therapy, perhaps via chemical or herbal therapy. In the present study, we aimed to identify the antioxidant and antibacterial activities of Saussurea costus roots. The study aimed to harness S. costus plant as antimicrobial via assessment of its antibacterial efficacy against pathogens by disc diffusion and minimum inhibitory concentration (MIC) tests. Methods: Alcoholic extract of S. costus roots was tested for antioxidant activity using diphenyl picrylhydrazyl (DPPH) and antibacterial effects on a few common bacterial species (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Proteus spp.). Result: The contents of S. costus extracts revealed of the presence of therapeutic principle components with variety of medicinal effects, including alkaloids, terpenoid, phenols and others. Different concentration of extracts have comparable antioxidant activity to ascorbic acid (81.96%). Similarly, different concentrations of the extract have confirmed antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli with no impacts on Proteus spp.

Molecular Epidemiological Characteristics of Staphylococcus pseudintermedius, Staphylococcus coagulans, and Coagulase-Negative Staphylococci Cultured from Clinical Canine Skin and Ear Samples in Queensland.

Background/Objectives: Infections in dogs caused by methicillin-resistant staphylococci (MRS) present limited treatment options. This study's objective was to investigate the molecular epidemiology of Staphylococcus spp. cultured exclusively from clinical canine skin and ear samples in Queensland, Australia, using whole-genome sequencing (WGS). Methods: Forty-two Staphylococcus spp. isolated from clinical canine skin and ear samples, from an unknown number of dogs, were sourced from two veterinary diagnostic laboratories between January 2022 and May 2023. These isolates underwent matrix-assisted laser desorption ionisation- time of flight bacterial identification, minimum inhibitory concentration testing using SensititreTM plates and WGS. Phylogenetic trees and core genome multilocus sequence typing (cgMLST) minimum spanning trees (MSTs) were constructed. Results: The isolates included methicillin-resistant and -sensitive S. pseudintermedius (MRSP: 57.1%, 24/42; and MSSP: 19.1%, 8/42), methicillin-resistant and -sensitive S. coagulans (MRSC: 14.3%, 6/42; and MSSC: 2.4%, 1/42) and methicillin-resistant coagulase-negative staphylococci (MR-CoNS: 7.1%, 3/42). Thirty-nine isolates were included after WGS, where all MRS harboured the mecA gene. Eighteen sequence types (STs) were identified, including three novel MRSP and six novel MSSP STs. MRSP ST496-V-VII (23%; 9/39) and MRSP ST749-IV-(IVg) (12.8%; 5/39) were commonly isolated. Phylogenetic analysis of single nucleotide polymorphisms showed that MRSP, MRSC and MSSC were similar to globally isolated staphylococci from canine skin and ear infections. Using cgMLST MSTs, MRSP isolates were not closely related to global strains. Conclusions: Our findings revealed a genotypically diverse geographical distribution and phylogenetic relatedness of staphylococci cultured from clinical canine skin and ear samples across Queensland. This highlights the importance of ongoing surveillance to aid in evidence-based treatment decisions and antimicrobial stewardship.

In-cell NMR reveals metabolic adaptations in central carbon pathways driving antibiotic tolerance in Salmonella Typhimurium.

Antibiotic tolerance presents a significant challenge in eradicating bacterial infections, as tolerant strains can survive antibiotic treatment, contributing to the recurrence of infections and the development of resistance. However, unlike antibiotic resistance, tolerance is not detectable by standard susceptibility assays such as minimal inhibitory concentration (MIC) tests. Consequently, antibiotic tolerance often goes unnoticed in clinical settings. Bacterial metabolism is closely linked to antibiotic efficacy, and thus presents as a potential target for novel diagnostic methods. Recent advancements in nuclear magnetic resonance (NMR) spectroscopy, including dynamic nuclear polarization (DNP-NMR), enable a non-invasive real-time approach to analyzing bacterial metabolism. In this study, we applied both 1H and in-cell 13C NMR spectroscopy to investigate metabolic adaptations in a tolerance-evolved Salmonella Typhimurium strain, C10, developed through ten cycles of ampicillin treatment. Our results demonstrated that despite similar MICs and growth rates, the C10 strain exhibited a 25-fold increase in tolerance compared to the wild-type, while exhibiting lower metabolic activity. Under ampicillin stress, however, the C10 strain maintained higher metabolic activity and demonstrated greater resilience in glucose consumption and metabolite production relative to the wild-type. Using DNP-NMR, rapid metabolic shifts in the C10 strain were identified within 10 minutes of exposure to high concentrations of ampicillin, characterized by accumulation of key metabolites such as pyruvate and acetate. Overall, our findings underscore the potential of real-time NMR-based analyses to provide deeper insights into antibiotic tolerance and distinguish between susceptible and tolerant bacterial strains.

Optimization of the Antibacterial Activity of a Three-Component Essential Oil Mixture from Moroccan Thymus satureioides, Lavandula angustifolia, and Origanum majorana Using a Simplex-Centroid Design.

The rise of antibiotic-resistant pathogens has become a global health crisis, necessitating the development of alternative antimicrobial strategies. This study aimed to optimize the antibacterial effects of essential oils (EOs) from Thymus satureioides, Lavandula angustifolia, and Origanum majorana, enhancing their efficacy through optimized mixtures. This study utilized a simplex-centroid design to optimize the mixture ratios of EOs for maximal antibacterial and antioxidant effectiveness. The chemical profiles of the EOs were analyzed using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was assessed against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa using minimum inhibitory concentration (MIC) tests, while antioxidant activity was evaluated through DPPH (2,2-diphenyl-1-picrylhydrazyl), and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assays. The optimized essential oil mixtures demonstrated potent antibacterial activity, with MIC values of 0.097% (v/v) for E. coli, 0.058% (v/v) for S. aureus, and 0.250% (v/v) for P. aeruginosa. The mixture ratios achieving these results included 76% T. satureioides, and 24% O. majorana for E. coli, and varying proportions for other strains. Additionally, L. angustifolia essential oil exhibited the strongest antioxidant activity, with IC50 values of 84.36 µg/mL (DPPH), and 139.61 µg/mL (ABTS), surpassing both the other EOs and standard antioxidants like BHT and ascorbic acid in the ABTS assay. The study successfully demonstrates that optimized mixtures of EOs can serve as effective natural antibacterial agents. The findings highlight a novel approach to enhance the applications of essential oils, suggesting their potential use in food preservation and biopharmaceutical formulations. This optimization strategy offers a promising avenue to combat antibiotic resistance and enhance food safety using natural products.

Outbreak of carbapenem resistant Klebsiella pneumoniae in a neurorehabilitation unit: genomic epidemiology reveals complex transmission pattern in a tertiary care hospital.

Infections by Carbapenem-Resistant Enterobacterales in hospitals represent a severe threat but little is known on outbreaks in rehabilitation wards caused by Klebsiella pneumoniae producing Klebsiella pneumoniae Carbapenemase (KPC-Kp). We report an outbreak by KPC-Kp, in a Neurorehabilitation Unit in Italy, analysed through Whole-Genome Sequencing (WGS) for transmission routes reconstruction to improve management of KPC-Kp infections in rehabilitation units. We investigated cases and KPC-Kp isolates collected from February to October 2022 from hospital surveillance. Carbapenem resistance was identified with disk diffusion and minimal inhibitory concentration tests, carbapenemase production through immunochromatographic lateral flow assays. All isolates were genotyped through WGS to highlight possible phylogenetic relationships. The most likely transmission networks of KPC-Kp, were reconstructed with Bayesian discrete-time stochastic models. 19 patients were colonized by KPC-Kp. Two isolates belonged to sporadic STs (ST348 and ST219) while 9/19 and 8/19 isolates belonged to ST307 and ST716, respectively. Among ST307 isolates, we identified two genomically distinct clusters of five and two cases. All ST716 isolates were highly similar. Genotyping and the reconstruction of transmission networks of KPC-Kp based on genomic data identified seven independent introductions into the Neurorehabilitation Unit rather than a single outbreak as initially hypothesized before genomic investigation. Three of the seven introductions generated chains of secondary infections, while the remaining four remained single cases. The outbreak root-causes were identified in temporary staff shortage and insufficient microbiological surveillance. Measures were adopted accordingly and the outbreak ended. The study highlights the critical role of genomic epidemiology in hospital outbreaks.

Keratin nanoparticles derived from feather waste for novel antibacterial delivery.

The global rise of bacterial resistance demands innovative strategies to enhance antibiotic efficacy. This study investigates keratin nanoparticles (KNPs) derived from waste chicken feathers as sustainable drug carriers. Antibacterial activity of KNPs was evaluated against Staphylococcus aureus and Escherichia coli using antibacterial sensitivity assays, including disc diffusion and minimum inhibitory concentration tests, while cytotoxicity was evaluated on human lymphoma cells. KNPs exhibited excellent biocompatibility, showing no cytotoxic effects on human cells or bacteria. Penicillin and vancomycin were successfully loaded onto KNPs at 4 °C, 25 °C, and 50 °C temperatures for 2 and 20-hour. Loading onto KNPs enhanced the antibacterial efficacy of penicillin and vancomycin by 4-fold and 3.8-fold, respectively, against S. aureus at 37 °C. Enhanced antibacterial efficacy was attributed to molecular interactions between keratin and penicillin, as demonstrated by molecular docking analysis. The analysis revealed that the β-lactam ring of penicillin was encapsulated within the keratin matrix, potentially shielding it from enzymatic degradation by penicillinase. This protective mechanism preserves the antibiotic's structural integrity and antibacterial activity. These findings highlight the potential of KNPs as effective drug carriers in combating resistance mechanisms. This research underscores the transformative role of sustainable biological macromolecules in modern medicine, offering a promising approach to combat antibiotic resistance.

Reliability of various Antimicrobial Susceptibility Testing Methods for Piperacillin/tazobactam in challenging Escherichia coli isolates.

Piperacillin/tazobactam antimicrobial susceptibility testing (AST) against Enterobacterales can be challenging. The aim of this study was to assess the reproducibility of various automated (Vitek®2) and non-automated AST methods (broth microdilution (BMD), minimum inhibitory concentration (MIC) test strip, and disk diffusion) for piperacillin/tazobactam in 'challenging' E. coli isolates. We performed 20 repeated AST for seven clinical E. coli isolates: two resistant to piperacillin/ tazobactam but susceptible for amoxicillin/ clavulanic acid, four isolates with various beta-lactamases coding genes (two blaTEM-1, one blaOXA-1, and one with plasmidal blaampC.), and one isolate where VITEK® 2 initially could not produce MIC measurement for piperacillin/ tazobactam (i.e. no results generated). Upon repetition, the same MIC as the mode value (i.e. the most frequent MIC value of each AST method) was found between 21% to 87% (BMD), 46% to 100% (VITEK®2), and 48% to 100 % (gradient test) of the repetitions. The range of percentage essential agreement (EA, i.e. ±1 doubling dilution from this mode value) was 53% to 100% (BMD), 63% to 100% (VITEK®2), and 100% (gradient test). Percentage categorical agreement (CA, same susceptible of resistant category using EUCAST breakpoint v 14.0) ranged from 71% to 100% (BMD), 85% to 92% (VITEK®2), 76% to 100% (gradient test) and 100% (disk diffusion). In conclusion, this study provides insights into the reliability of AST results for piperacillin/ tazobactam in challenging E. coli isolates. While the results indicate that most methods are generally reproducible, certain isolates may present inconsistent MIC results.

Minimum initiatory concentration distribution of Mecillinam in clinical Staphylococcus saprophyticus isolates from Europe.

Staphylococcus saprophyticus is the second most common bacteria causing uncomplicated urinary tract infections (UTI). It is considered non-susceptible to mecillinam, with no defined breakpoint and only few available minimal inhibitory concentration (MIC) observations. However, this consideration does not correlate with clinical outcome. With this study, we aimed to provide a comprehensive MIC distribution analysis of mecillinam for S. saprophyticus, which could be useful for determining potential breakpoints. We studied 112 isolates of S. saprophyticus from human urine samples from four European countries. The broth microdilution and MIC test strip methods were used to determine mecillinam MIC. Broth microdilution MICs ranged from 4 to ≥ 256 mg/L, with a binary clustering at 32-64 and ≥256 mg/L. The MIC were duplicated for each isolate with similar results. The MIC distribution from the test strip method aligned well with the results from the broth microdilution method. Disc diffusion test yielded an 8 mm inhibitory zone in three isolates with MIC of 32 mg/L. Considering mecillinam concentration in the urine usually reach 200 mg/L in conventional treatment, the clinical success frequently seen with pivmecillinam treatment for UTI caused by S. saprophyticus may be explained by the MIC cluster of 32-64 mg/L. This cluster might be identified by an 8 mm inhibitory zone in disc diffusion tests. Clinical studies with MIC data are needed to examine potential breakpoints. As of now, clinicians should not switch empirical pivmecillinam treatment to other antibiotics based solely on the presence of S. saprophyticus.

A multicenter performance evaluation of cefiderocol MIC results: ComASP in comparison to CLSI broth microdilution.

There are very limited commercial methods available to clinical laboratories for cefiderocol minimum inhibitory concentration (MIC) testing. The Compact Antimicrobial Susceptibility Panel (ComASP) Cefiderocol method includes iron-depleted cation-adjusted Mueller-Hinton broth, which eliminates variability in cefiderocol MIC results based on iron levels. The lyophilized multi-well format of ComASP also provides for room temperature storage. In comparison to what an individual lab may do for method verification, this multi-site, multi-isolate study provides a robust evaluation and greater assurance to clinical microbiologists of the method's accurate and reproducible performance.

THE EFFECTIVENESS OF GREEN SEAWEED (Ulva reticulate) ANTIBACTERIAL COMPOUND EXTRACT ON THE BACTERIA Vibrio parahaemolyticus

Green seaweed (Ulva reticulata) is found in many parts of Indonesia. The potential of green seaweed is not widely known to the public, even though it is considered a parasite on other types of seaweed. The purpose of this study was to determine the antibacterial compounds contained in green seaweed and their effectiveness against Vibrio parahaemolyticus bacteria. Green seaweed was extracted by maceration method and then qualitative and quantitative tests were carried out. After that, the minimum inhibitory concentration test was carried out and continued with the minimum bactericidal concentration test and the inhibition test with 5 treatments and 3 replications. The data from the qualitative and quantitative test of seaweed, the minimum inhibitory concentration and the minimum bactericidal were analyzed descriptively, while the data from the inhibition zone test was analyzed statistically by ANOVA. The results of qualitative and quantitative tests showed that green seaweed contained flavonoids (6.4909 mg/g), tannins (70.7500 mg/g) and saponins (443.7286 mg/g). The results of the minimum inhibitory concentration test showed that the concentration of 3.125% was the minimum concentration to inhibit bacterial growth. In the inhibition test, it can be seen that P4 (6%) is the best treatment. The results of statistical analysis show that the treatments given are significantly different, except that P4 (6%) and P5 (7,5%) are not significantly different. From this study it can be concluded that green seaweed extract is effective in inhibiting the growth of Vibrio parahaemolyticus bacteria.

Characterization and Genetic analysis of Actinomycetes from Mangrove and Coastal Environments: Enzyme Production, Dye Degradation and Antibiotic Resistance

ABSTRACT: Actinomycetes from mangrove and coastal environments were studied for their potential in biotechnology and environmental management. This research aimed to isolate and characterize these microbes, focusing on enzyme production, dye degradation, and antibiotic resistance. Samples were collected from various mangrove and coastal sites. Actinomycetes were isolated using selective media and identified through morphological and biochemical tests. Genetic characterization was performed using 16S rRNA sequencing. Enzyme production was evaluated through specific proteases, lipases, and cellulase assays. Dye degradation studies involved incubating actinomycetes with synthetic dyes and measuring degradation efficiency using spectrophotometric methods. Antibiotic resistance was assessed using disk diffusion and minimum inhibitory concentration (MIC) test. The study focused on isolating a variety of Actinomycetes from mangrove and coastal environments, assessing their potential for enzyme production and dye degradation.

Enterotoxigenic profile, biofilm production, and antimicrobial resistance of Bacillus cereus isolated from rice-based food marketed in southern Mexico

Bacillus cereus is responsible for food poisoning worldwide; thus, the characterization of strains isolated from food, in this case rice, is essential. The objective of this study was to identify the toxigenic profile, lytic enzymes, antimicrobial resistance, and biofilm production of B. cereus strains isolated from rice. The genetic profile of toxins and biofilm-related genes in the strains was determined by endpoint PCR. Biofilm formation was visualized using safranin staining, and the evaluation of lytic enzymes was conducted in culture media. Psychrophilic characteristics were monitored by assessing the growth of the strains at refrigeration temperature. The GTG5 technique was employed to determine the genetic diversity of the strains, and their antimicrobial resistance was validated through minimum inhibitory concentration testing. The strains of B. cereus s.l. isolated from rice contained genes for enterotoxins and genes associated with biofilm production. However, the strains did not possess the cereulide gene. The strain isolated from fried rice was the only one that contained the hbl toxin gene and the eps2 operon. Interestingly, this strain was the only one that did not produce biofilm. It exhibited intermediate sensitivity to erythromycin, was positive for amylase activity, showed high lecithinase activity, and was capable of growing at refrigeration temperature.

Antimicrobial Susceptibility Pattern of Community Isolates of Urinary Tract Infection in Bangladesh

Background: Overuses and injudicious uses of maximum antibiotics that have been prescribed empirically in community acquired UTI are being the prime cause of increasing resistance pattern among uropathogens in Bangladesh. There are minimum reports on antimicrobial resistance pattern among uropathogens in different regions of Bangladesh. No reports have been carried out to determine the response of uropathogens to fosfomycin yet in our country. So, the study aimed to determine the prevalence of uropathogens causing UTI in community and to determine the increasing resistance pattern among them with special emphasis on their ciprofloxacin and fosfomycin resistance status. Methodology: Identification of isolated bacteria was performed from collected 187 culture positive cases. Their antimicrobial resistance pattern was determined by Kriby- Bauer modified disc diffusion test. Minimum inhibitory concentration test of ciprofloxacin was performed among the ciprofloxacin resistant bacteria by agar dilution method. Result: The study demonstrated a higher prevalence of UTI in female (70.1%) than in male (29.9%). The most common isolated bacteria was E. coli (80.2%) followed by Klebsiellaspp. Higher resistance rate of 171 Enterobacteriaceae to ampicillin and 3rd generation cephalosporins was observed 71.9% and 49.1%-59.7% respectively in all 6 districts of Bangladesh. Ciprofloxacin resistance has been found higher 43.9% and 50%among Enterobacteriaceae and Staphylococcus spp. More than 50% of ciprofloxacin resistant bacteria had MIC 64ug/ml. All the strains of Enterobacteriaceae were sensitive to fosfomycin except 20% Klebsiella. Conclusion: Rising antimicrobial resistance pattern among uropathogens in different districts provide physicians an important information to make a discreet choice of antibiotics in empiric therapy of community acquired UTI in Bangladesh to reduce further evolution of multidrug resistant organisms. Central Medical College Journal Vol 8 No 1 January 2024 Page: 38-46

Minimum inhibitory concentrations of extended spectrum cephalosporins: A systematic review and meta-analysis of Neisseria gonorrhoeae treatment failures.

Neisseria gonorrhoeae is one of the recognised global antimicrobial resistance priorities. Extended spectrum cephalosporins, the last remaining reliable antimicrobial, increasingly fail to clear N. gonorrhoeae infections, especially pharyngeal gonorrhoea, leading to limited future treatment options. We conducted a systematic review and meta-analysis of gonococcal treatment failures and compared the minimum inhibitory concentrations (MIC) of isolates from pharyngeal and extra-pharyngeal anatomical sites (PROSPERO registration: CRD42020189101). The overall pooled mean MIC for cefixime was 0.17 mg/L (95% [CI]: 0.07, 0.41) and ceftriaxone was 0.10 mg/L (95% [CI]: 0.05, 0.22). For cefixime, the mean MIC estimates for pharyngeal and extra-pharyngeal treatment failures were 0.05 mg/L (95% [CI]: 0.02, 0.14) and 0.29 mg/L (95% [CI]: 0.11, 0.81), and for ceftriaxone 0.09 mg/L (95% [CI]: 0.03, 0.22) and 0.14 mg/L (95% [CI]: 0.03, 0.73), respectively. The pooled mean MICs for pharyngeal isolates are below the phenotypic European Committee on Antimicrobial Susceptibility Testing (EUCAST) resistance breakpoint for both antimicrobials (>0.125 mg/L). Our findings underscore the need to review the current resistance breakpoints used for pharyngeal infection and the urgency to establish international standards for MIC testing, and advance efforts of the World Health Organization's global action plan to control the spread and impact of antimicrobial resistance in N. gonorrhoeae. Ongoing susceptibility testing of gonococcal isolates and surveillance of treatment failures are central to informing appropriate public health responses.

Inducing programmed cell death trough MazEF system to combat Staphylococcus aureus: A non-antibiotic treatment candidate.

The aim of the present study was to evaluate the role of extracellular death factor (EDF) derived from Escherichia coli in the induction of programmed cell death (PCD) in methicillin-resistant and -susceptible Staphylococcus aureus (MRSA and MSSA). The confirmation of bacterial strains as well as the minimum inhibitory concentration (MIC) test were performed according to CLSI, 2022. The extraction and efficacy determination of EDF as well as the CFU assessment were done. The expression of mazE and mazF gens in different conditions was evaluated by Real-time PCR. The likely formation of persister cells from MRSA and MSSA, and the possible synthesis of EDF in old cultures of these pathogens was evaluated, as well. The combination of EDF of two E. coli strains and sub-MIC rifampin reduced the CFUs of MRSA and MSSA strains in mid-logarithmic growth phase while increased the expression of mazF several times more than mazE gene. The expression of these genes in different conditions were unlike. EDF was produced in the old cultures of MRSA and MSSA. The supernatant of E. coli 25922 was more powerful than the clinical strain ones to decrease the CFUs of the MRSA and MSSA. The EDF derived from E. coli in combination with sub-MIC rifampin could induce PCD in MRSA and MSSA through activation of the MazEF system. This phenomenon could be exploited as a non-antibiotic treatment candidate to combat the infections caused by the antibiotic-resistant pathogens. However, more studies should be performed in this regard.