Reduction In Bacterial Load Research Articles

YafN-YafO toxin-antitoxin system contributes to stress resistance and virulence of avian pathogenic Escherichia coli.

Avian pathogenic Escherichia coli (APEC) is a major threat to the poultry industry, causing bloodstream and extraintestinal infections. Type II toxin-antitoxin (TA) systems are known to aid bacterial pathogens in adapting to stress, promoting persister cell formation, and enhancing virulence. While type II TA systems have been extensively studied in many pathogens, APEC-derived TAs have received limited attention. Our study focused on the YafN-YafO type II TA system in APEC O2 strain E058. Using bacterial two-hybrid and pull-down assays, we confirmed the interaction between YafN and YafO. Electrophoretic mobility shift assays (EMSA) and lacZ fusion reporter assays demonstrated that YafN negatively autoregulates its own operon. The deletion of yafNO resulted in a significant reduction in persister cell formation under antibiotic and environmental stress (P < 0.01). Moreover, the yafNO mutant showed a ∼3-fold reduction in survival within chicken macrophages and attenuated virulence in chicken infection models, with a 44-fold increase in LD50 and ∼80-fold reduction in bacterial loads in blood and tissues (P < 0.01). These results demonstrate that the YafN-YafO is an active type II TA system in APEC E058, contributing to both stress resistance and virulence. Targeting this system could offer a novel strategy for controlling APEC infections.

Cold atmospheric plasma therapy as a novel treatment for Berlin Heart EXCOR pediatric cannula infections.

Cold atmospheric plasma (CAP) therapy has been recognized as effective treatment option for reducing bacterial load in chronic wounds, such as adult ventricular assist device (VAD) driveline exit-site infections. Currently, there have been no reports on the safety and efficacy of CAP therapy for pediatric cannula infections and inflammations in paracorporeal pulsatile VADs. The mechanical strength of Berlin Heart EXCOR cannulas were tested both before and after CAP treatment (SteriPlas, Adtec Healthcare Limited, UK) to prove material safety. A ring tensile test of 20 untreated and 20 CAP-treated (5 min) EXCOR cannulas (Ø12mm), assessed the force at the breaking point of the cannulas (Fmax), at 25% (F25%) and 50% (F50%) of the maximum displacement. Additionally, the scanning electron microscope (SEM) micrographs for both groups examined any surface changes. Finally, the case of a 13-year-old male EXCOR patient with cannula infections, treated with CAP over 100 days, is presented. The invitro measurements revealed no statistically significant differences in mechanical strength between the control and CAP group for F25% (8.18 ± 0.36 N, vs. 8.02 ± 0.43 N, p = 0.21), F50% (16.87 ± 1.07 N vs. 16.38 ± 1.32 N, p = 0.21), and FMAX (44.55 ± 3.24 N vs. 42.83 ± 4.32 N, p = 0.16). No surface structure alterations were identified in the SEM micrographs. The patient's cannula exit-sites showed a visible improvement in DESTINE wound staging, reduction in bacterial load and inflammatory parameters after CAP treatment without any side effects. Overall, CAP therapy proved to be a safe and effective for treating EXCOR cannula exit-site wound healing disorders in one pediatric patient, but further studies should investigate this therapy in more detail.

Functional characterization of MMAR_1296 in Mycobacterium marinum and its potential as a vaccine candidate.

The Pro-Glu/Pro-Pro-Glu (PE/PPE) family proteins in mycobacteria plays a crucial role in pathogenesis and immune evasion. These proteins characterized by unique structures with conserved sequences. This study elucidated the specific immunological functions of MMAR_1296 from marine mycobacterium. Expressing MMAR_1296 in Mycobacterium smegmatis (M. smegmatis) led to significant alterations in bacterial morphology, as well as reduced survival of M. smegmatis under adverse in vitro conditions and within macrophages. Furthermore, transcriptome analysis of mouse macrophages indicated that natural immunity-related pathways were upregulated in the group infected with M. smegmatis recombinantly expressing MMAR_1296. Moreover, the mycobacterium Growth Inhibition Assays(MGIA)in mice demonstrated that M. smegmatis expressing MMAR_1296 exerted a significant inhibitory effect against Mycobacterium abscessus (M. abscessus) and Mycobacterium marinum (M. marinum) infections. Immunization challenge experiments in mice further confirmed its protective effects, showing a reduction in organ bacterial loads by 1 log10 value compared to the positive control group. These findings indicate that MMAR_1296 is a promising vaccine candidate for M. abscessus and M. marinum. Given that PE/PPE protein family is also a crucial component of Mycobacterium tuberculosis (M. tuberculosis) antigens, further exploration of sequence functions based on MMAR_1296 could reveal broader applications of PE/PPE proteins family for M. tuberculosis treatment. This study supported vaccine development targeting PE/PPE proteins in mycobacteria and paves the way for broader applications.

Midgut immune profiling and functional characterization of Aedes aegypti ABC transporter gene(s) using systemic and local bacterial challenges

BackgroundThe mosquito midgut is crucial for digestion and immune interactions. It produces several immune factors that protect the organ from invading pathogens and can limit their propagation. Studies on mosquito midgut transcriptome following pathogen exposure have revealed the presence of non-canonical immune genes, such as ABC transporters, whose function in insect immunity remains unexplored. Therefore, this study focuses on identifying and characterising the immune role of ABC transporters in the midgut of Aedes aegypti, a primary arboviral vector.MethodsTo identify the midgut-expressed ABC transporters, the mosquitoes were challenged with a mixture of gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria, and the expression of all ABC transporters was analysed with PCR using gene-specific primers. Furthermore, the transcriptional alterations of midgut ABC transporters were explored at different time points upon a thoracic nano-injection (systemic challenge) or infectious blood meal (local challenge) of the bacterial mixture through quantitative real-time PCR (qPCR), and one gene was selected for RNAi-mediated gene silencing and its role assessment in midgut immune responses.ResultsThe expression of all 48 microbial-induced midgut-expressing Ae. aegypti ABC transporter genes upon systemic or local bacterial challenges was analyzed. Based on the transcriptomic data and potential immune expression similar to the well-known immune gene defensin, AaeABCG3 was selected for RNAi-mediated gene silencing and characterization. The AaeABCG3 gene silencing exhibited a significant reduction of midgut bacterial load through the induction of nitric oxide synthase (NOS) in sugar-fed and systemic bacterial-challenged mosquitoes. In contrast, midgut bacterial load was significantly regulated by induction of defensin A and cecropin G in the late hours of local bacterial challenges in AaeABCG3-silenced mosquitoes.ConclusionsThe silencing of AaeABCG3 modulated the mosquito midgut immune response and disturbed the midgut microbiota homeostasis. The systemic immune responses of AaeABCG3-silenced mosquitoes were influenced by the JAK-STAT pathway with no induction of Toll and IMD immune pathways. Interestingly, Toll and IMD immune pathways actively participated in the late hours of local bacterial challenges, suggesting that the route of infection influences these immune responses; however, the molecular mechanism behind these phenomena still needs to be explored. Overall, this work provides significant insight into the importance of ABC transporters in mosquito immunity.Graphical

P-1099. Correlation Analysis of Cefiderocol In vitro Activity and In vivo Efficacy Against Acinetobacter baumannii Strains with Difficult-to-Read MIC Endpoints

Abstract Background Cefiderocol (FDC) is a siderophore-conjugated cephalosporin with broad activity against Gram-negative bacteria, including Acinetobacter baumannii. For some isolates, determining the minimum inhibitory concentration (MIC) endpoints for FDC can be difficult due to the trailing growth phenomenon. Recently guidance on how to determine the MIC when trailing occurs has been updated in the CLSI M100 document, to enhance MIC reproducibility. In this study, we determined MICs of A. baumannii strains that show difficult to determine MIC endpoint due to trailing according to the updated CLSI guidance and analyzed correlations between MICs and in vivo efficacy. In vivo bacterial growth or reduction from start of treatment with cefiderocol against Acinetobacter baumannii in the neutropenic murine thigh infection model using humanized pharmacokinetic exposure of cefiderocol. In vivo (S): mean of reduction in bacterial cell number at 24 hours after initial treatment with cefiderocol (mean of change &amp;lt;0 log10 colony forming unit (CFU) /thigh) CFU/thigh), in vivo (R): mean of increase in bacterial cell number at 24 hours after initial treatment with cefiderocol (mean of change ≥0 log10 CFU/thigh). MIC values shown blue, orange, and red indicate susceptible, intermediate, and resistant, respectively, according to CLSI guideline 2024. Methods MICs were determined according to the 2024 CLSI guidance using iron-depleted cation-adjusted Mueller-Hinton broth (ID-CAMHB) from BD-BBL for 43 A. baumannii isolates, including 13 strains that show severe trailing. All strains had been evaluated in vivo in the murine thigh infection model using humanized pharmacokinetic exposure of FDC (1). Categorical agreements between MICs and in vivo efficacy in murine thigh infection model Susceptible (S), Non-susceptible (NS), breakpoints as published by CLSI (2024), In vivo (S): mean of reduction in bacterial cell number at 24 hours after initial treatment with cefiderocol (mean of change &amp;lt;0 log10 colony forming unit (CFU)/thigh, in vivo (R): mean of increase in bacterial cell number at 24 hours after initial treatment with cefiderocol (mean of change ≥0 log10 CFU/thigh). Results FDC MIC range of tested A. baumannii strains was 0.12 to &amp;gt;32 μg/mL. Among 19 strains that showed a reduction in bacterial load after treatment with FDC in the murine thigh infection model, 94.7% (18/19 strains) were categorized as FDC susceptible (Figure and Table 1). Among 24 strains that showed increase in bacterial load after treatment with FDC in vivo, 87.5% (21/24 strains) were categorized as FDC non-susceptible. The categorical agreement of MICs and in vivo efficacy was 90.7% (39/43). As for the 13 strains that showed severe trailing, the categorical agreement of MICs and in vivo efficacy was 84.6% (11/13, Table 2). The updated CLSI guidance did not impact the overall agreement that was obtained earlier using the previous CLSI guidance (Table 1, 2). Categorical agreements between MICs and in vivo efficacy in murine thigh infection model for 13 strains that showed severe trailing Susceptible (S), Non-susceptible (NS), breakpoints as published by CLSI (2024), In vivo (S): mean of reduction in bacterial cell number at 24 hours after initial treatment with cefiderocol (mean of change &amp;lt;0 log10 colony forming unit (CFU)/thigh, in vivo (R): mean of increase in bacterial cell number at 24 hours after initial treatment with cefiderocol (mean of change ≥0 log10 CFU/thigh). Conclusion Our correlation analysis between MICs and in vivo efficacy in thigh infection model confirms the validity of MIC endpoint determinations described in CLSI M100 document, including strains that show severe trailing. Reference: 1. Monogue L, et al. Antimicrob Agents Chemother. 2017;61(11):e01022-17. Disclosures Hidenori Yamashiro, Shionogi &amp; Co., Ltd.: Employee Motoyasu Onishi, PhD, Shionogi &amp; Co., Ltd.: Employee Naomi Anan, MSc, Shionogi &amp; Co., Ltd.: Employee Boudewijn L. DeJonge, PhD, Shionogi Inc.: Employee Christopher M. Longshaw, PhD, Shionogi BV: Employee Miki Takemura, n/a, Shionogi &amp; Co., Ltd.: Employee Yoshinori Yamano, PhD, Shionogi &amp; Co., Ltd.: Employee

Curcumin-laden hydrogel coating medical device for periprosthetic joint infection prevention and control.

The Periprosthetic Joint Infection (PJI) is one of the most important complications of the joint arthroplasty. This surgical procedure is rising worldwide and is further affecting the public health because of the widespread resistance to antibiotics. New therapeutic strategies and innovative antimicrobial biomaterials development are needed to eradicate pathogens without inducing resistance and accelerating recovery. In this direction, herein Curcumin I- (Cur-) loaded DAC® (Defensive Antibacterial Coating, a hydrogel based on hyaluronic acid conjugate to polylactic acid, hereafter named DAC) has been built on. To incorporate Cur in the DAC, so obtaining Cur-DAC (Cur ≅ 0.93 mg/g), the generally recognized as safe (GRAS) propylene glycol (PG) was used as cosolvent. The drugs combinations of Cur (≅0.93 mg/g) and Vancomycin (Van) (at low dose that is ≅ 0.033 mg/g) within the hydrogel (Cur/Van-DAC) was experienced too. Hydrogels were prepared and characterized by rheological investigations and their erosion together with the drug release profile over the time evaluated in physiological conditions. The nanohydrogels produced upon water dilution were characterized by AFM, DLS, and UV/Vis absorption and emission spectroscopies. Superior Cur stability over pH-, solvent- and photo-induced degradations resulted in the DAC matrix. The photoinduced antimicrobial activity of Cur-DAC against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium was evaluated by spreading loaded DAC-based hydrogel onto titanium disk mimicking prosthesis, thus detecting a good reduction of bacterial load after 30 min of exposure to light and a subsequent decrease of cells number at 24 h. The drug association in Cur/Van-DAC demonstrated the best activity against MRSA, even in the presence of nutrients, respect to established DAC loaded with high amounts of Van (ranging from 18.7 mg/g to 45.8 mg/g) used during the surgery, due to the photo-antibacterial activity of Cur, becoming promising to prevent and control joint infections.

The Efficacy and Safety of Prophylactic Treatment Methods for Cutibacterium Acnes Infection in the Shoulder: A Systematic Review of Level of Evidence I Randomized Controlled Trials.

Cutibacterium acnes (C. acnes), formerly Propionibacterium acnes (P. acnes), is the most common pathogen responsible for postoperative shoulder infections. Prevention of shoulder infection is crucial to improving patient outcomes, prolonging implant longevity, and reducing costs. The purpose of this study is to evaluate the effectiveness of various prophylactic treatments for C. acnes in the shoulder. A systematic review of 15 randomized controlled trials was conducted to evaluate the effectiveness of various skin preparation methods in the reduction of C. acnes for patients undergoing shoulder surgery. Three electronic databases were queried as follows: PubMed, Embase, and the Cochrane Library databases. Data extraction for this study was performed by three independent reviewers, and only level I studies were included. Outcomes were assessed based on the effectiveness of the method used; side effects were also analyzed. Fifteen studies were included in this review. Seven studies utilized a regimen of at-home treatment in the days leading up to culture sampling, while the other eight studies administered treatment just prior to sampling. Seven studies found their respective treatment methods to be statistically significant. No preparation methods applied immediately prior to sampling showed conclusive superiority. The application benzoyl peroxide in the days prior to sampling showed significantly lower rates of colonization when compared to control groups in five separate studies. There remains no consensus on the optimal skin preparation method immediately prior to surgery, however, acne cream applied in the days leading up to surgery has been shown to significantly reduce the bacterial load of C. acnes. While BPO appears to be the superior method of prophylactic treatment, it is also associated with higher rates of complications and skin reactions following treatment; thus, caution is warranted. Further studies should investigate whether this reduction in bacterial load translates to meaningfully lower rates of periprosthetic joint infections.

Explainable deep learning and virtual evolution identifies antimicrobial peptides with activity against multidrug-resistant human pathogens.

Artificial intelligence (AI) is a promising approach to identify new antimicrobial compounds in diverse microbial species. Here we developed an AI-based, explainable deep learning model, EvoGradient, that predicts the potency of antimicrobial peptides (AMPs) and virtually modifies peptide sequences to produce more potent AMPs, akin to in silico directed evolution. We applied this model to peptides encoded in low-abundance human oral bacteria, resulting in the virtual evolution of 32 peptides into potent AMPs. Of these, the 6 most effective were synthesized and tested against multidrug-resistant pathogens and demonstrated activity against carbapenem-resistant species Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii, and vancomycin-resistant Enterococcus faecium. The most potent AMP, pep-19-mod, was validated in vivo, achieving over 95% reduction in bacterial loads in mouse models of thigh infection through both systemic and local administration. Our approach advances the automatic identification and optimization of AMPs.

Targeting InhA in drug-resistant Mycobacterium tuberculosis: potent antimycobacterial activity of diaryl ether dehydrozingerone derivatives.

Tuberculosis (TB) remains a major global threat, with 10 million new cases and 1.5 million deaths each year. In multidrug-resistant tuberculosis (MDR-TB), resistance is most commonly observed against isoniazid (INH) and rifampicin (RIF), the two frontline drugs. Isoniazid resistance is predominantly linked to mutations in the InhA gene, which encodes an enzyme involved in mycolic acid synthesis, a vital component of the mycobacterial cell wall. Mutations in InhA reduce drug binding, rendering INH ineffective. These morbidity and mortality figures, along with the fact that the rise and global spread of drug-resistant TB, underscores the need for the discovery of novel therapeutics. In this direction, we have previously synthesized, characterized, and screened a library of diaryl ether dehydrozingerone derivatives against mycobacteria and identified two best hits, 7 and 14, based on bacteriostatic activities. The present study aimed to thoroughly investigate the antituberculosis potential of these compounds, particularly regarding drug-resistant TB. Our findings revealed that both compounds exhibited tuberculocidal activity against the standard laboratory strain Mycobacterium tuberculosis (M. tb) H37Rv, with minimal bactericidal concentrations (MBC) of 4μg/ml for compound 7 and 8μg/ml for compound 14. Next, concentration vs time-kill kinetics of both these compounds showed concentration-dependent bactericidal activities against M. tb and complete pathogen eradication from culture at just 16× MIC. Both compounds were found to be suitable for combination regimens as their interactions with isoniazid and rifampicin against M. tb were observed to be synergistic. Additionally, 7 and 14 exhibited minimal hemolysis against human RBCs and less cytotoxicity was observed against three human cell lines up to 1000μM. Molecular docking revealed that these compounds bind more effectively to M. tb InhA, including its mutant forms where isoniazid binding is impaired, outperforming both isoniazid and triclosan in binding affinity. Importantly 7 and 14 showed potent activity against drug-susceptible clinical isolates and two isoniazid-resistant M. tb clinical isolates equivalent to that against M. tb H37Rv. The most interesting observation was that both compounds were found to be effective against three multi-drug resistant (MDR) strains of M. tb, thereby depicting their potential against drug-resistant TB. An ex vivo assay on RAW 264 cells infected with M. tb demonstrated a significant reduction in bacterial load at 8× MIC, revealing the fact that these compounds are highly effective against intracellular M. tb H37Rv. To the best of our knowledge, this is the first study that reports promising antimycobacterial potential of 7 and 14 against drug-susceptible, isoniazid-resistant, and MDR tuberculosis which warrants further exploration considering the need for new anti-TB medicine.

A Longer Duration of Intravenous Antibiotic Treatment for Patients with Early Periprosthetic Joint Infections Is Not Associated with a Lower Failure Rate.

In recent years, many studies have demonstrated the efficacy of an early switch to oral antibiotics after surgical treatment in orthopedic-related infections. However, large analyses on periprosthetic joint infections (PJIs) are lacking. We conducted a retrospective observational multicenter study in patients diagnosed with an early post-operative PJI, defined as one occurring <3 months after the index arthroplasty and treated with debridement, antibiotics, and implant retention (DAIR). Patients from Europe and the USA were included. We took advantage of the fact that an early oral antibiotic switch is routine practice in Europe as opposed to a long duration of intravenous (IV) antibiotic treatment in the USA. Failure was defined as the clinical need for (i) a second unintended DAIR procedure, (ii) implant removal, (iii) suppressive antibiotic treatment, or (iii) PJI-related death, all within one year after DAIR. A total of 668 patients were included. A total of 277 received IV antibiotics for <14 days, 232 between 14 and 27 days, and 159 for >27 days. The overall 1-year failure rate within the 3 groups was 41.5%, 44.4%, and 42.1%, respectively (p = 0.80). This observation remained when excluding patients who failed during IV therapy. A longer duration of IV therapy seemed beneficial for those patients with a high pre-operative C-reactive protein level and lack of modular component exchange. In early post-operative PJIs, a longer duration of IV therapy is not associated with a lower failure rate but may be continued until a sufficient bacterial load reduction has been achieved.

Evaluating the effect of virgin coconut oil pulling on viral load, bacterial load and inflammatory mediator levels in chronic periodontitis - A clinical study.

Periodontitis and dental caries are among the most prevalent oral diseases, with chronic periodontitis being a multifactorial, infectious condition that leads to inflammation in the supporting structures of the teeth, progressive attachment loss, and bone resorption. Chronic periodontitis is driven by a consortium of pathogenic microorganisms. This study aimed to evaluate the efficacy of virgin coconut oil (VCO) pulling in reducing the microbial load and inflammatory mediators responsible for chronic periodontitis, in comparison to chlorhexidine (CHX) mouthwash and distilled water. Thirty patients diagnosed with chronic periodontitis were randomly allocated into three groups. Group A served as the control and used distilled water for oral rinsing, Group B used chlorhexidine mouthwash, and Group C performed oil pulling with virgin coconut oil. Pre-operative subgingival plaque samples were collected from all participants, followed by complete scaling and root planing. Post-operative samples were collected after four weeks. Both pre- and post-treatment samples were subjected to real-time PCR (rtPCR) and enzyme-linked immunosorbent assay (ELISA) to quantify viral and bacterial loads, as well as levels of key inflammatory mediators. A significant reduction in viral load, bacterial load, and inflammatory mediators was observed in both the VCO and CHX groups compared to the distilled water group. The reductions in the VCO and CHX groups were statistically significant, with comparable efficacy between the two interventions. Virgin coconut oil pulling demonstrated a significant reduction in microbial and inflammatory markers in patients with chronic periodontitis, showing similar efficacy to chlorhexidine mouthwash. Given its comparable therapeutic effects and reduced side effect profile, VCO presents a viable alternative to chlorhexidine for managing chronic periodontitis.

Tobramycin-resistant small colony variant mutant of Salmonella enterica serovar Typhimurium shows collateral sensitivity to nitrofurantoin

ABSTRACT The increasing antibiotic resistance poses a significant global health challenge, threatening our ability to combat infectious diseases. The phenomenon of collateral sensitivity, whereby resistance to one antibiotic is accompanied by increased sensitivity to another, offers potential avenues for novel therapeutic interventions against infections unresponsive to classical treatments. In this study, we elucidate the emergence of tobramycin (TOB)-resistant small colony variants (SCVs) due to mutations in the hemL gene, which render S. Typhimurium more susceptible to nitrofurantoin (NIT). Mechanistic studies demonstrate that the collateral sensitivity in TOB-resistant S. Typhimurium SCVs primarily stems from disruptions in haem biosynthesis. This leads to dysfunction in the electron transport chain (ETC) and redox imbalance, ultimately inducing lethal accumulation of reactive oxygen species (ROS). Additionally, the upregulation of nfsA/B expressions facilitates the conversion of NIT prodrug into its active form, promoting ROS-mediated bacterial killing and contributing to this collateral sensitivity pattern. Importantly, alternative NIT therapy demonstrates a significant reduction of bacterial load by more than 2.24-log10 cfu/g in the murine thigh infection and colitis models. Our findings corroborate the collateral sensitivity of S. Typhimurium to nitrofurans as a consequence of evolving resistance to aminoglycosides. This provides a promising approach for treating infections due to aminoglycoside-resistant strains.

Assessment of tuberculosis drug efficacy using preclinical animal models and in vitro predictive techniques

Tuberculosis (TB) killed approximately 1.3 million people in 2022 and remains a leading cause of death from the bacteria Mycobacterium tuberculosis (M.tb); this number of deaths was surpassed only by COVID-19, caused by the SARS-CoV-2 virus. The alarming emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) M.tb strains presents an urgent need for effective new treatments. Our study aimed to determine the synergistic effects of antibiotic combinations against M.tb. Using a high-throughput in vitro checkerboard assay, we evaluated the interactions of Bedaquiline (BDQ) and other antibiotics including Capreomycin (CAP), Linezolid (LIN), and Sutezolid (SUT) against M.tb H37Rv. BDQ and CAP demonstrated in vitro enhanced effect, which prompted further investigation in vivo using the murine low dose aerosol (LDA) model. After aerosol challenge with M.tb, C57BL/6 mice were treated with BDQ, CAP, or their combination, starting 28 days post-infection. The antimicrobial treatment lasted four weeks, and the bacterial burden in lung and spleen tissues was assessed at the end of treatment. At 4 weeks post-treatment, a significant reduction in bacterial load was observed within the lungs and spleens of mice given BDQ alone or given as a BDQ/CAP combination compared to the untreated group. In contrast, CAP monotherapy led to an increase in bacterial load within the lung and no significant difference in bacterial burden in the spleen in comparison to the untreated mice. These results were confirmed in the guinea pig model of TB, where both BDQ and the BDQ/CAP combination treatment led to a decrease in bacterial burden in the lung and spleen, whereas CAP had no significant effect on bacterial burden at the 4-week post treatment timepoint. We next determined whether there may be differences in vitro with the BDQ/CAP combination against M.tb lineages 1, 2 and 4. We determined that in vitro enhanced effect was not observed in some representative strains of M.tb lineage 4, indicating variability in drug effectiveness across M.tb lineages. This research underscores the complexity of TB treatment and the critical need for innovative approaches to combat this global health threat.

Regimen comprising clarithromycin, clofazimine and bedaquiline is more efficacious than monotherapy in a mouse model of chronic Mycobacterium avium lung infection.

Mycobacterium avium , a leading non-tuberculous mycobacterium (NTM) pathogen, causes chronic pulmonary infections, particularly in individuals with underlying lung conditions or immunosuppression. Current treatments involve prolonged multi-drug regimens with poor outcomes and significant side effects, highlighting the urgent need for improved therapies. Using a BALB/c mouse model of chronic M. avium pulmonary disease, we evaluated the efficacy of individual antibiotics- clarithromycin, clofazimine, and rifabutin-and combination regimens including clarithromycin+bedaquiline and clarithromycin+clofazimine+bedaquiline. Clarithromycin demonstrated potent bactericidal activity, reducing lung bacterial burden by 2.2 log 10 CFU, while clofazimine transitioned from bacteriostatic to bactericidal, achieving a 1.7 log 10 CFU reduction. Rifabutin was bacteriostatic against M. avium MAC 101 but ineffective against MAC 104. The triple-drug regimen of clarithromycin+clofazimine+bedaquiline was the most effective, achieving a 3.3 log 10 CFU reduction in bacterial load, with 98% clearance within the first week and continued efficacy over eight weeks. Gross pathology confirmed these results, with granulomatous lesions observed only in untreated or rifabutin-treated mice. Combination therapy demonstrated enhanced efficacy compared to monotherapy. The findings underscore the potential of oral clarithromycin+clofazimine+bedaquiline or clarithromycin+clofazimine regimen as a promising therapeutic strategy for M. avium pulmonary disease.

Effect of ceramic dressings and silver-impregnated dressings on bacterial load and wound closure: a comparative study.

Wound healing is a series of complex and dynamic processes which occur in several stages. Optimal wound healing is essential for restoring the integrity and function of the affected area. Although medicated wound dressings have been extensively employed to control wound infection, the risks associated with antimicrobials make the use of non-medicated alternatives necessary. Nevertheless, the relationship between the concentrations of medicated wound dressings and their antimicrobial activities, along with their wound healing efficacies, still remains unclear. Non-medicated wound dressings are an alternative to dressings that contain active ingredients acting as antimicrobials or antiseptics. In the present study, the researchers examined the reduction of bacterial load as the primary endpoint and the healing rate as the secondary endpoint, comparing microporous ceramic dressings to silver-impregnated dressings in participants from two outpatient wound management clinics. The study included 25 participants in the silver-impregnated dressing (control) group and 28 participants in the ceramic dressing (study) group. The participants' wounds were assessed through MolecuLight i:X (MolecuLight Inc., Canada) wound tracing and MolecuLight i:X fluorescence imaging to measure the wound size, as well as presence of a bacterial load of >104 colony forming units/g at weeks 1, 2, 3 and 4. The results indicated that there was a significant difference in the distribution over the categories of bacterial load cleared after weeks 1, 2, 3 or 4 in the two groups. Moreover, the bacterial load cleared significantly faster in the study group (p=0.001). Mean wound size was 10.93cm2 (range: 0.10-37.95cm2) in the control group and 11.48cm2 (range: 0.80-60cm2) in the study group. In the maximum likelihood regression analysis, the mean reduction in wound area for the study group was greater than that for the control group. The study concluded that the ceramic dressings could be an effective alternative to silver-impregnated dressings when treating infected wounds.

Oreochromicin-2 shows antimicrobial and immunostimulant effect against respiratory pathogens in pigs.

Porcine respiratory diseases have a huge economic impact on pig production. The highest incidence of these diseases is commonly linked to Streptococcus suis, Pasteurella multocida and Bordetella bronchiseptica, some of which are zoonotic posing a risk to human health. The inappropriate and excessive use of conventional antibiotics, as usual procedure for treating respiratory diseases in pigs, has generated the emergence of antimicrobial resistance (AMR), which urgently requires the development of alternative approaches to current antimicrobials. Antimicrobial peptides (AMPs) have rapidly garnered interest as novel therapeutic candidates. Oreochromicin-2 (Oreoch-2), an AMP previously isolated from Oreochromis niloticus gills, has shown broad antibacterial properties against several species. However, studies about its effect on porcine respiratory pathogens and its potential use for the treatment of swine respiratory diseases are not available. In this work we determined the in vitro antimicrobial activity of the peptide against S. suis by a broth microdilution method. Oreoch-2 showed a MIC of 3.13μM against this pathogen. For in vivo experiments, Yorkshire x Landrace crossbred (LYxL35) weaning pigs aged 30-33days were allocated in pens containing ten pigs each. To study the influence of the peptide on health status, a total clinical score was determined. The administration of Oreoch-2 improved the clinical behavior of the animals, similar to the conventional antibiotic shotapen, respect to the placebo group. A reduction of bacterial loads in the respiratory tract and lungs was observed in Oreoch-2-treated animals as compared to the placebo group. It was shown that peptide treated-piglets displayed significantly higher serum IgG concentration compared to the control group. These results demonstrated Oreoch-2 potential as an antimicrobial and immunostimulant drug candidate against respiratory diseases in pigs.

Dentition Type as a Determinant of Microbial Load Reduction by Antimicrobial Photodynamic Therapy in Deep Dentin Caries: A Systematic Review and Meta-analysis.

Antimicrobial photodynamic therapy (aPDT) is a protocol proposed for reduction of bacterial load in deep dentin caries in primary and permanent dentitions. However, considering the difference in the morphology of dentinal tubules in primary and permanent teeth, the effect of this treatment may be different on the two dentition types. This systematic review and meta-analysis aimed to assess the effect of type of dentition as a determinant of microbial load reduction by aPDT in deep dentin caries. An electronic search was conducted in Scopus, Web of Science, Cochrane, Medline, and Embase databases, from the first record until April 30, 2022. After article screening by three reviewers, seven studies were included in this meta-analysis. The mean log of Streptococcus mutans (S. mutans) count, Lactobacillus spp. count, and the entire bacteria in the cavity before and after aPDT was calculated with 95% confidence interval (CI), and compared between the two groups of primary and permanent teeth by the random effect model. The I2 test was applied to assess the heterogeneity of the findings. Publication bias was evaluated by visual examination of the funnel-plot symmetry. Of 7 retrieved articles, analysis of 3 studies on permanent teeth showed that aPDT caused a significant reduction in total bacterial count in the cavity [SMD: 0.64, 95% CI:(0.31, 0.96), p= 0.0001), S. mutans count [SMD: 0.92, 95% CI:(0.58, 1.25), p< 0.0001], and Lactobacillus spp. [SMD: 1.1, 95% CI:(0.76, 1.45), p< 0.00001)]. Analysis of the remaining 4 studies on primary teeth indicated that aPDT had a significant effect only on S. mutans count [SMD: 0.60, 95% CI:(0.23, 0.97), p= 0.001), and its effect on total bacterial count of the cavity [SMD: 0. 90, 95% CI:(-0.02, 1.82), p= 0.05] and Lactobacillus spp. [SMD: 0.18, 95% CI:(-0.29, 0.64), p= 0.45)] was not significant. The results showed that aPDT could serve as an effective adjunct for reduction of microbial load in permanent teeth.

In vivo reduction of biofilm seeded on orthopaedic implants.

Electromagnetic induction heating has demonstrated in vitro antibacterial efficacy over biofilms on metallic biomaterials, although no in vivo studies have been published. Assessment of side effects, including thermal necrosis of adjacent tissue, would determine transferability into clinical practice. Our goal was to assess bone necrosis and antibacterial efficacy of induction heating on biofilm-infected implants in an in vivo setting. Titanium-aluminium-vanadium (Ti6Al4V) screws were implanted in medial condyle of New Zealand giant rabbit knee. Study intervention consisted of induction heating of the screw head up to 70°C for 3.5 minutes after implantation using a portable device. Both knees were implanted, and induction heating was applied unilaterally keeping contralateral knee as paired control. Sterile screws were implanted in six rabbits, while the other six received screws coated with Staphylococcus aureus biofilm. Sacrifice and sample collection were performed 24, 48, or 96 hours postoperatively. Retrieved screws were sonicated, and adhered bacteria were estimated via drop-plate. Width of bone necrosis in retrieved femora was assessed through microscopic examination. Analysis was performed using non-parametric tests with significance fixed at p ≤ 0.05. The width of necrosis margin in induction heating-treated knees ranged from 0 to 650 μm in the sterile-screw group, and 0 to 517 μm in the biofilm-infected group. No significant differences were found between paired knees. In rabbits implanted with sterile screws, no bacteria were detected. In rabbits implanted with infected screws, a significant bacterial load reduction with median 0.75 Log10 colony-forming units/ml was observed (p = 0.016). Induction heating was not associated with any demonstrable thermal bone necrosis in our rabbit knee model, and might reduce bacterial load in S. aureus biofilms on Ti6Al4V implants.

Effect of Ginger Extract and Polyphosphate on Microbiological Properties of Chicken Meat

The present study was aimed to evaluate the effect of Trisodium phosphate (TSP), fresh ginger rhizome extract (GE) and their mix on some microbiological properties of chicken meat. The chicken carcasses samples were collected after evisceration processes and before coming into the immersion chiller, from the production line of private automatic poultry slaughterhouse in Dhamar city, Yemen. The chicken `s carcasses were divided into four treatment groups and control: The G-I was acts as control (3 carcasses), G-II (6 carcasses), G-III (6 carcasses) and G-IV (3 carcasses) were dipped in 3 and 5% ginger extracts, 6 and 8% TSP solutions and mix of TSP (6%) and ginger extract (3%) respectively. Measurements were taken before and post treatment at 0, 48 and 72 hrs. at 4±1˚C. The results showed a significant reducing(P&lt;0.05) in populations of total bacteria counts and Staphylococcus by 0.85 and 0.79 log cfu/ml in treated group with 8% TSP; while, in treated groups with 6%, 8% TSP and with the mix of (3% GE + 6 % TSP) caused a significant reduction in Salmonella counts by 0.82, 1.05 and 0.89 log cfu/ml respectively. Changes in microbial loads during cold storage indicated that chicken meat group treated with 8% TSP resulted in a significant reduction in total bacterial counts by 3.45 log cfu/ml compared to control group 4.36 log cfu/ml after 48 hrs. of storage at 4±1˚C; while, Salmonella count was significantly reduced by 2.46 log cfu/ml as compared to control 3.78 log cfu/ml after 72 hrs. of storage at 4±1˚C. In conclusion, Trisodium phosphate, ginger, and Trisodium phosphate and ginger in combination at different concentration exhibited antibacterial activities in reduction of bacterial counts and load on chicken meat. Trisodium phosphate compound showed more efficacy compared to ginger extracts. The treatments of chicken meat with TSP, GE and their mix increased the shelf life of the meat. Further studies are needed to study the effect of other plant extract on microbiological properties of chicken meat.

Unraveling Water-Soluble Constituents of Basil (Ocimum basilicum L.) in Relation to Their Toxicity and Anti-Typhoidal Activity in Mouse Models.

Plants are the major source of natural flavour ingredients reported for their wide applications in food and pharmaceuticals, oral care and wellness products, etc. We have investigated the water-soluble fractions (WSF) of basil tetraploid (O. basilicum L.) for their toxicity and biological potential against Salmonella Typhimurium, a pathogen causing around one million cases of illnesses in the United States every year. The WSF obtained using a Clevenger-type apparatus was further divided into two equal parts, one each for in-vivo toxicity evaluation and quality assessments, respectively. The proportions of major phenylpropanoid identified as meta-eugenol in the WSF were found in the range of 42.8-57.9 %, which was substantially in higher proportion as compared to essential oil (20.9-23.0 %). Based on sub-acute oral toxicity data, WSF has not shown any adverse effect with levels as high as 500 μL/25 g body weight in Swiss albino mice. Besides, the WSF also exhibited a maximum reduction in bacterial load in mice infected with Salmonella Typhimurium in a dose-dependent manner. We have shown the biological potential of basil water-soluble fraction as an effective bacterial load-suppressing agent for the prevention of Salmonella infections in animal model.