High Bacterial Load Research Articles

Mycobacterium marinum MMAR_0267-regulated copper utilization facilitates bacterial escape from phagolysosome

The host limits Mycobacterium tuberculosis (Mtb) by enriching copper in high concentrations. This research investigates how Mtb escapes copper stress. The membrane protein encoded by Mtb Rv0102, when its homolog in M. smegmatis (MSMEG_4702) was knocked out, resulted in a fourfold decrease in intracellular copper levels and enhanced tolerance to elevated extracellular copper concentrations. Similarly, knockout mutants of its homolog in M. marinum (MMAR_0267) showed increased virulence in zebrafish and higher bacterial load within macrophages. In THP-1 cells infected with MMAR_0267 deletion mutants, the intracellular survival of these mutants increased, along with reduced THP-1 cell apoptosis. Deficiency in copper down-regulated the transcriptional level of the virulence factor CFP-10 in M. marinum, suppressed cytosolic signaling via the macrophage STING pathway, leading to decreased production of IFN-β and reduced cell apoptosis. In conclusion, these findings highlight the significant impact of copper on the survival and reproduction of mycobacteria, underscoring the importance of studying mycobacterial adaptation mechanisms in copper-rich environments.

Occurrence and antimicrobial resistance of Campylobacter jejuni isolated from poultry and hospitalized diarrheal patients in Pakistan

The leading human enteropathogen Campylobacter jejuni (C. jejuni) is recognized as a major public-health concern, due to emerging multidrug resistant (MDR) strains, and associated post-infectious complications. Therefore, the present study determined the occurrence of C. jejuni in diarrheal cases and poultry, in Khyber Pakhtunkhwa Province, Pakistan, and associated antimicrobial resistance patterns. In total, 840 samples were collected from clinical and different poultry sources between May 2019 to April 2020, to determine the occurrence, seasonal variations, bacterial loads in diverse poultry samples, age-related variations in human infections as well as associated antimicrobial resistance patterns of C. jejuni, highlighting its “One Health significance” at the human-food interface. Clinical samples (n = 240) from five age-groups of hospitalized diarrhoea patients, showed occurrence rate of 39 %, which peaked in the summer and was highest in children under 5. In poultry samples, 57 % (342/600) were positive for C. jejuni, varied from 45 % (109/240) in chicken meat to 65 % (233/360) in farm samples. Except frozen meat, C. jejuni-positive poultry samples showed seasonal contamination levels, with summer having the highest bacterial loads. In chicken meat, 2 % of positive samples (2/109) had bacterial loads <1 logCFU/g, while 20 % (22/109) exceeding 3log CFU/g. Grocery store samples showed lower bacterial contamination. All human and poultry isolates (n = 436) were resistant to nalidixic acid (100 %) and none to amikacin (0 %). Of these, 66 % showed multidrug resistance, with 9 % (38/436) resistant to panel of seven out of eight antibiotics tested. This study highlights the high occurrence of and concerns about MDR C. jejuni in Khyber Pakhtunkhwa, Pakistan, particularly in young children.

Current vaccination strategy against Piscirickettsia salmonis in Chile based only on the EM-90 genogroup shows incomplete cross-protection for the LF-89 genogroup

Piscirickettsia salmonis, the primary bacterial disease in Chilean salmon farming, necessitates a constant refinement of control strategies. This study hypothesized that the current vaccination strategy for SRS control in the Chilean Atlantic salmon aquaculture industry, which has been in place since 2017 (ALPHA JECT® 5.1 plus LiVac®), solely relies on vaccines formulated with the EM-90 genogroup of P. salmonis (PS-EM-90), triggering a partial cross-immunity response in fish infected with the LF-89 genogroup (PS-LF-89). Relative Percent Survival (RPS) and cell-mediated immune (CMI) response were evaluated in Atlantic salmon post-smolts vaccinated with the standard vaccination strategy but challenged with both PS-EM-90 and PS-LF-89, in addition to other vaccination strategies considering primo vaccination and booster with other commercial vaccines and the possible enhancing effects of the combination with a natural immunomodulator (PAQ-Xtract®) administered orally. The intraperitoneal (I.P.) challenge was performed after 2395°-days (DD) after the start of the immunostimulant delivery, 1905 DD after the primo vaccination, and 1455 DD after the booster vaccination. Unvaccinated fish showed 73.6 and 41.7 % mortality when challenged with PS-EM-90 and PS-LF-89, respectively. Fish infected with PS-LF-89 died significantly faster (21 days post-infection, dpi) than fish challenged with PS-EM-90 (28 dpi) (p = 0.0043) and had a higher probability of death (0.4626) than fish challenged with PS-EM-90. RPS had a significant positive correlation with the PS-EM-90 load of the P. salmonis genogroup (r = 0.540, p < 0.01) but not with the PS-LF-89 load (r = 0.155, p > 0.05). This demonstrated that the immunization strategies were more effective in lowering PS-EM-90 loads, resulting in higher survival rates in fish challenged with PS-EM-90. The current industry vaccination strategy recorded a 100 % RPS when fish were challenged with PS-EM-90, but the RPS dropped significantly to 77 % when fish were challenged with PS-LF-89, meaning that the strategy did not show complete cross-protection. But after adding PAQ-Xtract®, the RPS improved from 77 % to 92 % in fish that were vaccinated with the standard method but then challenged with PS-LF-89. The most effective vaccination strategy was based on LiVac® as primo vaccination and ALPHA JECT® 5.1 plus LiVac® as booster vaccination, with or without PAQ-Xtract®, in both PS-EM-90 (100 %) and PS-LF-89 (96 %) challenged fish. The serum concentration of anti-P. salmonis IgM did not show a correlation with the protection of immunization strategies expressed in survival. Low serum IL-12 and high serum IFNγ concentrations showed a correlation with higher bacterial loads and lower survival. Aggregate analysis showed a significant correlation between higher numbers of CD8+ cells in the head-kidney, higher fish survival, and a lower bacterial load. The immunization strategies were safe for fish and induced only mild microscopic lesions in the gut. Taken together, our results help to better understand the biological interaction between P. salmonis and post-smolt vaccinated Atlantic salmon to deepen the knowledge on vaccine-induced protection, CMI immune response, and cross-immunity applied to improve the current immunization strategy for SRS control in the Chilean salmon industry.

Enhance the Antimycobacterial Activity of Streptomycin with Ebselen as an Antibiotic Adjuvant Through Disrupting Redox Homeostasis.

Tuberculosis (TB) remains a major health threat worldwide, and the spread of drug-resistant (DR) TB impedes the reduction of the global disease burden. Ebselen (EbSe) targets bacterial thioredoxin reductase (bTrxR) and causes an imbalance in the redox status of bacteria. Previous work has shown that the synergistic action of bTrxR and sensitization to common antibiotics by EbSe is a promising strategy for the treatment of DR pathogens. Thus, we aimed to evaluate whether EbSe could enhance anti-TB drugs against Mycobacterium marinum (M. marinum) which is genetically related to Mycobacterium tuberculosis (Mtb) and resistant to many antituberculosis drugs. Minimum inhibitory concentrations (MIC) of isoniazid (INH), rifampicin (RFP), and streptomycin (SM) against M. marinum were determined by microdilution. The Bliss Independence Model was used to determine the adjuvant effects of EbSe over the anti-TB drugs. Thioredoxin reductase activity was measured using the DTNB assay, and its effects on bacterial redox homeostasis were verified by the elevation of intracellular ROS levels and intracellular GSH levels. The adjuvant efficacy of EbSe as an anti-TB drug was further evaluated in a mouse model of M. marinum infection. Cytotoxicity was observed in the macrophage cells Raw264.7 and mice model. The results reveal that EbSe acts as an antibiotic adjuvant over SM on M. marinum. EbSe + SM disrupted the intracellular redox microenvironment of M. marinum by inhibiting bTrxR activity, which could rescue mice from the high bacterial load, and accelerated recovery from tail injury with low mammalian toxicity. The above studies suggest that EbSe significantly enhanced the anti-Mtb effect of SM, and its synergistic combination showed low mammalian toxicity in vitro and in vivo. Further efforts are required to study the underlying mechanisms of EbSe as an antibiotic adjuvant in combination with anti-TB drug MS.

Association of Staphylococcus aureus Bacterial Load and Colonization Sites With the Risk of Postoperative S. aureus Infection.

The independent effects of extranasal-only carriage, carriage at multiple bodily sites, or the bacterial load of colonizing Staphylococcus aureus (SA) on the risk of developing SA surgical site infections and postoperative bloodstream infections (SA SSI/BSIs) are unclear. We aimed to quantify these effects in this large prospective cohort study. Surgical patients aged 18 years or older were screened for SA carriage in the nose, throat, or perineum within 30 days before surgery. SA carriers and noncarriers were enrolled in a prospective cohort study in a 2:1 ratio. Weighted multivariable Cox proportional hazard models were used to assess the independent associations between different measures of SA carriage and occurrence of SA SSI/BSI within 90 days after surgery. We enrolled 5004 patients in the study cohort; 3369 (67.3%) were SA carriers. 100 SA SSI/BSI events occurred during follow-up, and 86 (86%) of these events occurred in SA carriers. The number of colonized bodily sites (adjusted hazard ratio [aHR], 3.5-8.5) and an increasing SA bacterial load in the nose (aHR, 1.8-3.4) were associated with increased SA SSI/BSI risk. However, extranasal-only carriage was not independently associated with SA SSI/BSI (aHR, 1.5; 95% CI, 0.9-2.5). Nasal SA carriage was associated with an increased risk of SA SSI/BSI and accounted for the majority of SA infections. Higher bacterial load, as well as SA colonization at multiple bodily sites, further increased this risk.

16S rRNA amplicon sequencing and antimicrobial resistance profile of intensive care units environment in 41 Brazilian hospitals.

Infections acquired during healthcare setting stay pose significant public health threats. These infections are known as Healthcare-Associated Infections (HAI), mostly caused by pathogenic bacteria, which exhibit a wide range of antimicrobial resistance. Currently, there is no knowledge about the global cleaning process of hospitals and the bacterial diversity found in ICUs of Brazilian hospitals contributing to HAI. Characterize the microbiome and common antimicrobial resistance genes present in high-touch Intensive Care Unit (ICU) surfaces, and to identify the potential contamination of the sanitizers/processes used to clean hospital surfaces. In this national, multicenter, observational, and prospective cohort, bacterial profiles and several antimicrobial resistance genes from 41 hospitals across 16 Brazilian states were evaluated. Using high-throughput 16S rRNA amplicon sequencing and real-time PCR, the bacterial abundance and resistance genes presence were analyzed in both ICU environments and cleaning products. We identified a wide diversity of microbial populations with a recurring presence of HAI-related bacteria among most of the hospitals. The median bacterial positivity rate in surface samples was high (88.24%), varying from 21.62 to 100% in different hospitals. Hospitals with the highest bacterial load in samples were also the ones with highest HAI-related abundances. Streptococcus spp., Corynebacterium spp., Staphylococcus spp., Bacillus spp., Acinetobacter spp., and bacteria from the Flavobacteriaceae family were the microorganisms most found across all hospitals. Despite each hospital particularities in bacterial composition, clustering profiles were found for surfaces and locations in the ICU. Antimicrobial resistance genes mecA, bla KPC-like, bla NDM-like, and bla OXA-23-like were the most frequently detected in surface samples. A wide variety of sanitizers were collected, with 19 different active principles in-use, and 21% of the solutions collected showed viable bacterial growth with antimicrobial resistance genes detected. This study demonstrated a diverse and spread pattern of bacteria and antimicrobial resistance genes covering a large part of the national territory in ICU surface samples and in sanitizers solutions. This data should contribute to the adoption of surveillance programs to improve HAI control strategies and demonstrate that large-scale epidemiology studies must be performed to further understand the implications of bacterial contamination in hospital surfaces and sanitizer solutions.

Freshwater microalgae Nannochloropsis limnetica for the production of β-galactosidase from whey powder

This study investigated the first-ever reported use of freshwater Nannochloropsis for the bioremediation of dairy processing side streams and co-generation of valuable products, such as β-galactosidase enzyme. In this study, N. limnetica was found to grow rapidly on both autoclaved and non-autoclaved whey-powder media (referred to dairy processing by-product or DPBP) without the need of salinity adjustment or nutrient additions, achieving a biomass concentration of 1.05–1.36 g L−1 after 8 days. The species secreted extracellular β-galactosidase (up to 40.84 ± 0.23 U L−1) in order to hydrolyse lactose in DPBP media into monosaccharides prior to absorption into biomass, demonstrating a mixotrophic pathway for lactose assimilation. The species was highly effective as a bioremediation agent, being able to remove > 80% of total nitrogen and phosphate in the DPBP medium within two days across all cultures. Population analysis using flow cytometry and multi-channel/multi-staining methods revealed that the culture grown on non-autoclaved medium contained a high initial bacterial load, comprising both contaminating bacteria in the medium and phycosphere bacteria associated with the microalgae. In both autoclaved and non-autoclaved DPBP media, Nannochloropsis cells were able to establish a stable microalgae–bacteria interaction, suppressing bacterial takeover and emerging as dominant population (53–80% of total cells) in the cultures. The extent of microalgal dominance, however, was less prominent in the non-autoclaved media. High initial bacterial loads in these cultures had mixed effects on microalgal performance, promoting β-galactosidase synthesis on the one hand while competing for nutrients and retarding microalgal growth on the other. These results alluded to the need of effective pre-treatment step to manage bacterial population in microalgal cultures on DPBP. Overall, N. limnetica cultures displayed competitive β-galactosidase productivity and propensity for efficient nutrient removal on DPBP medium, demonstrating their promising nature for use in the valorisation of dairy side streams.

Assessment of Conservation Status of Petroleuciscus Borysthenicus Celensis From Gurban River, Romania by Identification of Parasites and Bacteria

The present research was conducted within the framework of a broader investigation with the objective of identifying freshwater parasites and bacteria on national territory, with the aim of gaining a deeper understanding of the relationships between parasites, hosts, and the environment, and to assess the potential detrimental effects of parasitic infestation on the conservation status of fish populations. Within this study, it was documented the first recordings of parasites Vorticella globularia and Epistylis sp. in the Romanian Petro-leuciscus borysthenicus celensis fish species. A total of 42 specimens were collected from the Gurban River to study their infestation status, focusing on the skin, gills, and fins. From the samples analyzed, 16 specimens presented signs of infestation with five distinct parasite species (Ichthyophthirius multifiliis, Dactylogyrus vastator, Trichodina acuta, Vorticella globularia and Epistylis sp) and four bacterial strains (Aeromonas veronii, Shewanella putrefaciens, Aeromona hydrophila, and Citrobacter freundii). The results indicate that the skin is the organ most severely impacted by parasites and bacteria, followed by the gills. The fins, on the other hand, are the least susceptible to infection. Furthermore, the significant amount of parasitic infestation coupled with the high bacterial load of Aeromonas veronii indicates a plausible link between the two.

Surveillance of close contacts of patients with infectious tuberculosis: a prospective cohort study

BackgroundA long-term follow-up of close contacts to monitor their infection status is essential to formulate a promising screening strategy. The study aimed to assess the dynamics of tuberculosis (TB) infection using Interferon-γ release assay (IGRA) and determine risk factors associated with TB infection.MethodsDefinite TB patients were interviewed and their household contacts were screened for TB infection by IGRA during 12-month longitudinal investigation.ResultsWe included in our analyses 184 household contacts of 92 index TB patients. 87 individuals (47.3%) in contact group progressed to TB infection, of whom 86 developed into IGRA positive within 24 weeks. Close contacts with a higher age and comorbidities are easier to exhibit TB infection. Analysis showed that risk factors for becoming IGRA-positive individuals included residence, older age, comorbidities, BCG scar and high bacterial load. Contacts with BCG scar had a lower IGRA-positive rate.ConclusionIGRA conversion generally occurs within 24 weeks after exposure. The TB transmission happens since subclinical TB stage and the presence of BCG scar is an independent protective factor reducing risk of TB infection among close contacts. Repeated IGRA tests are sensible to conducted among close contacts at 24 weeks after exposure to identify the IGRA-positive individuals.

A blood-based 3-gene signature score for therapeutic monitoring in patients with pulmonary tuberculosis

ObjectiveTo assess the validity of Xpert Tuberculosis Fingerstick score for monitoring treatment response and analyze factors influencing its performance. Methods122 adults with pulmonary tuberculosis were recruited and stratified into three cohorts: Diabetic-drug-susceptible-TB (DM-TB), Non-diabetic-drug-susceptible-TB (NDM-TB) and Non-diabetic Multidrug-resistant TB (MDR-TB). Fingerstick blood specimens were tested at treatment initiation (M0) and the end of the first (M1), second (M2), and sixth month (M6) to generate a TB-score. ResultsThe TB-score in all participants yielded an AUC of 0.707 (95% CI: 0.579–0.834) at M2 when its performance was evaluated against sputum culture conversion. In all non-diabetes patients, the AUC reached 0.88 (95% CI: 0.756–1.000) with an optimal cut-off value of 1.95 at which sensitivity was 90.0% (95% CI: 59.6–98.2%) and specificity was 81.3% (95% CI: 70.0–88.9%). The mean TB score was higher in patients with low bacterial loads (n = 31) than those with high bacterial loads (n = 91) at M0, M1, M2, and M6, and was higher in non-cavitary patients (n = 71) than those with cavitary lesions (n = 51) at M0, M1, and M2. ConclusionXpert TB-score shows promising predictive value for culture conversion in non-diabetic TB patients. Sputum bacterial load and lung cavitation status have an influence on the value of TB score.

Bacteriological Analyses of Fish Mucus from Fish Market with Reference to Consumer’s Health

A study was conducted to evaluate the bacteria load present in fish mucus collected from Nanpura wholesale fish market during the period from 30th December 2022 to 20th February 2023. Total 20 fish mucus samples were determined by Total Plate Count (TPC) and identification of bacteria. High bacterial load with pathogens such as Escherichia coli (Gram negative bacteria) and Staphylococcus aureus (Gram positive bacteria) were found in all fresh and marine fish samples from study area. These pathogens can survive and multiply in fish, transferred into consumer by way of food and main source of fish poisoning, diarrhoea, meningitis and septicemia which cause health risk to consumer. The fishes were contaminated with pathogenic bacteria indicated poor handling of fishes, lack of preservation facility and unhygienic condition of study area. Thus, it is strongly recommended to improve the quality control and quality assurance systems of the study area to minimize the prevalence of pathogenic bacteria.

Endotypes of Exacerbation in Bronchiectasis: An Observational Cohort Study.

Rationale: Bronchiectasis is characterized by acute exacerbations, but the biological mechanisms underlying these events are poorly characterized. Objectives: To investigate the inflammatory and microbial characteristics of exacerbations of bronchiectasis. Methods: A total of 120 patients with bronchiectasis were enrolled and presented with acute exacerbations within 12 months. Spontaneous sputum samples were obtained during a period of clinical stability and again at exacerbation before receipt of antibiotic treatment. A validated rapid PCR assay for bacteria and viruses was used to classify exacerbations as bacterial, viral, or both. Sputum inflammatory assessments included label-free liquid chromatography-tandem mass spectrometry and measurement of sputum cytokines and neutrophil elastase activity. 16 s rRNA sequencing was used to characterize the microbiome. Measurements and Main Results: Bronchiectasis exacerbations showed profound molecular heterogeneity. At least one bacterium was identified in 103 samples (86%), and a high bacterial load (total bacterial load > 107 copies/g) was observed in 81 patients (68%). Respiratory viruses were identified in 55 (46%) patients, with rhinovirus being the most common virus (31%). PCR testing was more sensitive than culture. No consistent change in the microbiome was observed at exacerbation. Exacerbations were associated with increased neutrophil elastase, proteinase-3, IL-1β, and CXCL8. These markers were particularly associated with bacterial and bacterial plus viral exacerbations. Distinct inflammatory and microbiome profiles were seen between different exacerbation subtypes, including bacterial, viral, and eosinophilic events in both hypothesis-led and hypothesis-free analysis using integrated microbiome and proteomics, demonstrating four subtypes of exacerbation. Conclusions: Bronchiectasis exacerbations are heterogeneous events with contributions from bacteria, viruses, and inflammatory dysregulation.

Comparative analysis of Streptococcus agalactiae serotypes Ia and II isolates from China and Pakistan in a murine model: A focus on pathogenesis and immune response

Bovine mastitis, caused by Streptococcus agalactiae (Group B Streptococcus; GBS), poses significant economic challenges to the global dairy industry. Mouse models serves as valuable tools for assessing GBS-induced infections as an alternative to large animals. This study aimed to investigate the LD50 dose, organ bacterial load, and quantification of peritoneal leukocyte populations for GBS serotypes Ia and II isolates from China and Pakistan. Additionally, we measured indicators such as lactoferrin, albumin, and myeloperoxidase (MPO) activity. Pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-2) and anti-inflammatory cytokines (IL-10 and TGF-β) in serum and tissue samples were evaluated using ELISA and qPCR, respectively. BALB/c mice (4 mice per group) received individual intraperitoneal injections of 100 μl containing specific bacterial inoculum concentrations (ranging from 105 to 109 CFU per mouse) of Chinese and Pakistani GBS isolates (serotypes Ia and II). Control groups received 100 μL of sterile PBS. Results revealed that the LD50 bacterial dose causing 50 % mortality in mice was 107 CFU. The highest bacterial load in all experimental groups was quantified in the peritoneum, followed by blood, mammary gland, liver, spleen, lungs, and brain. The most significant bacterial dissemination was observed in mice inoculated with Pakistani serotype Ia at 24 h, with a subsequent notable decline in bacterial counts at day 3. Notably, infection with Pakistani serotype Ia showed a trend of increased total leukocyte counts, significantly higher than Pakistani serotype II, Chinese Serotype Ia, and Chinese serotype II. A substantial influx of neutrophils and lymphocytes was observed in response to all tested serotypes, with Pakistani serotype Ia inducing a significantly higher influx compared to other groups (Pakistani serotype II, Chinese serotype Ia, and Chinese serotype II). Furthermore, TNF-α, IL-1β, IL-2, and IL-6 expressions were significantly increased in mice one day after infection with the Pakistani serotype Ia. Compared to mice infected with the Pakistani serotype II, Chinese Serotype Ia, and Chinese serotype II, those infected with the Pakistani serotype Ia isolate exhibited the highest production of IL-10 and TGF-β, along with significantly increased concentrations of lactoferrin, albumin, and MPO. These findings suggest that the persistence and severity of infection caused by the Pakistani serotype Ia may be linked to its ability to spread to deeper tissues. This study enhances our understanding of the clinical characteristics of bovine mastitis caused by S. agalactiae in China and Pakistan.

Collaborative Cross mice have diverse phenotypic responses to infection with Methicillin-resistant Staphylococcus aureus USA300.

Staphylococcus aureus (S. aureus) is an opportunistic pathogen causing diseases ranging from mild skin infections to life threatening conditions, including endocarditis, pneumonia, and sepsis. To identify host genes modulating this host-pathogen interaction, we infected 25 Collaborative Cross (CC) mouse strains with methicillin-resistant S. aureus (MRSA) and monitored disease progression for seven days using a surgically implanted telemetry system. CC strains varied widely in their response to intravenous MRSA infection. We identified eight 'susceptible' CC strains with high bacterial load, tissue damage, and reduced survival. Among the surviving strains, six with minimal colonization were classified as 'resistant', while the remaining six tolerated higher organ colonization ('tolerant'). The kidney was the most heavily colonized organ, but liver, spleen and lung colonization were better correlated with reduced survival. Resistant strains had higher pre-infection circulating neutrophils and lower post-infection tissue damage compared to susceptible and tolerant strains. We identified four CC strains with sexual dimorphism: all females survived the study period while all males met our euthanasia criteria earlier. In these CC strains, males had more baseline circulating monocytes and red blood cells. We identified several CC strains that may be useful as new models for endocarditis, myocarditis, pneumonia, and resistance to MRSA infection. Quantitative Trait Locus (QTL) analysis identified two significant loci, on Chromosomes 18 and 3, involved in early susceptibility and late survival after infection. We prioritized Npc1 and Ifi44l genes as the strongest candidates influencing survival using variant analysis and mRNA expression data from kidneys within these intervals.

The Role of Kidney Intercalated Cells in the Immune Response Against UTIs

Introduction: Urinary tract infections (UTIs) are among the most prevalent infections. About 3 in 5 women will experience UTIs in their lifetime, resulting from a bacterial infection caused by uropathogenic E. coli (UPEC). Ascending UPEC first adhere to the collecting ducts, where intercalated cells (ICs) are essential for raising an innate immune response activated by UPEC-outer membrane lipopolysaccharide (LPS). Interestingly, individuals with distal renal tubular acidosis (dRTA) who have a mutation on the gene encoding the kidney anion exchanger 1 (kAE1) have a decreased abundance of IC and are at a higher risk for UTIs. The cellular mechanisms contributing to this higher vulnerability to UTIs remain unclear. Objective and Hypothesis: To enhance our understanding of the immune response mechanisms of collecting duct cells in dRTA patients during UTIs, we hypothesize that the loss of intercalated cells (ICs) in dRTA results in an inadequate immune response against UPEC. Methods: Mouse inner medullary collecting duct cells (mIMCD3) and a mouse strain with a knock-in mutation for kAE1 dRTA (specifically, R607H, equivalent to human R589H) were utilized in the study. We identified and quantified innate immunity markers in mIMCD3 cells exposed to vehicle, UPEC or LPS using qRT-PCR and immunoblot. Primary IC were prepared by magnetic-activated cell sorting (MACS). Various incubation conditions, including exposure to vehicle, LPS, control K12 bacteria, and UPEC for different time intervals were assessed to determine the best experimental conditions. Transurethral UPEC inoculation procedures were also performed to validate results obtained in the in vitro approaches. Results: Experiments on mIMCD3 cells showed a significant increase in the innate immunity marker adrenomedullin (ADM) following exposure to UPEC or LPS, compared to the control group. After 17 h, exposing the primary MACS-enriched ICs to UPEC significantly increased the adrenomedullin protein abundance. UPEC transurethral infections in dRTA mice resulted in a higher bacterial load and increased IL-1β, IL-6, and TNF-α mRNA and protein levels compared to WT mice at 24 post-UTI. In the transgenic mice, ADM gene expression was not up-regulated to the same extent as in WT mice, but LCN2/NGAL gene expression was significantly higher. Conclusions: Our study suggests that the loss of IC in a dRTA mouse model results in higher inflammation and reduced immunity against UPEC exposure. Our research will unravel new therapeutic leads on the intracellular signaling pathway(s) and cellular changes that result in IC-mediated renal protection. The findings may contribute to the development of novel therapeutics for UTIs. Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Institutes of Health Research (CIHR), University of Alberta Graduate Recruitment Scholarship (2023). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Utilization of Whey for Eco-Friendly Bio-Preservation of Mexican-Style Fresh Cheeses: Antimicrobial Activity of Lactobacillus casei 21/1 Cell-Free Supernatants (CFS).

Using whey, a by-product of the cheese-making process, is important for maximizing resource efficiency and promoting sustainable practices in the food industry. Reusing whey can help minimize environmental impact and produce bio-preservatives for foods with high bacterial loads, such as Mexican-style fresh cheeses. This research aims to evaluate the antimicrobial and physicochemical effect of CFS from Lactobacillus casei 21/1 produced in a conventional culture medium (MRS broth) and another medium using whey (WB medium) when applied in Mexican-style fresh cheese inoculated with several indicator bacteria (Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Listeria monocytogenes). The CFSs (MRS or WB) were characterized for organic acids concentration, pH, and titratable acidity. By surface spreading, CFSs were tested on indicator bacteria inoculated in fresh cheese. Microbial counts were performed on inoculated cheeses during and after seven days of storage at 4 ± 1.0 °C. Moreover, pH and color were determined in cheeses with CFS treatment. Lactic and acetic acid were identified as the primary antimicrobial metabolites produced by the Lb. casei 21/1 fermentation in the food application. A longer storage time (7 days) led to significant reductions (p < 0.05) in the microbial population of the indicator bacteria inoculated in the cheese when it was treated with the CFSs (MRS or WB). S. enterica serovar Typhimurium was the most sensitive bacteria, decreasing 1.60 ± 0.04 log10 CFU/g with MRS-CFS, whereas WB-CFS reduced the microbial population of L. monocytogenes to 1.67 log10 CFU/g. E. coli and S. aureus were the most resistant at the end of storage. The cheese's pH with CFSs (MRS or WB) showed a significant reduction (p < 0.05) after CFS treatment, while the application of WB-CFS did not show greater differences in color (ΔE) compared with MRS-CFS. This study highlights the potential of CFS from Lb. casei 21/1 in the WB medium as an ecological bio-preservative for Mexican-style fresh cheese, aligning with the objectives of sustainable food production and guaranteeing food safety.

Interpretation of biosafety in endodontics by means of a literature review using PRISMA 2020 methodology

Biosafety is of great importance in all areas of health care, including endodontic procedures, since they represent a high risk of biological transmission of diseases such as AIDS and hepatitis, among others. The aim of the study was to interpret biosafety in endodontics by means of a literature review using PRISMA 2020 methodology. It was an observational, retrospective and descriptive study corresponding to the exploratory level, following the guidelines of the PRISMA 2020 methodology, combining the terms 'biosafety' and 'endodontics' in the PubMed and Google Scholar databases. The results highlighted the importance of biosafety in endodontic procedures and it was found that endodontics is used to treat different types of endodontic infections with high bacterial loads, so the correct use of biosafety barriers and protocols is necessary, since the area of dentistry has a high risk of biological contagion. It was also shown that biosafety comprises a set of rules, precautions and guidelines used in various scientific research and teaching activities to prevent risks or infections associated with exposure to agents that may be infectious or present significant biological, chemical or physical risks. It was concluded that endodontics and its procedures require strict compliance with biosafety protocols to ensure a high success rate and safeguard the health of the professional, the patient and the work team

Quality, safety, and microbiological assessment of loose market milk and antibiotic resistance analysis of Escherichia coli isolates in different areas of Faisalabad, Pakistan

Unpacked milk consumption is common in developing countries like Pakistan, raising concerns regarding adulteration and pathogen contamination. This study analyzed market-sold unpacked milk samples (n = 40) from Faisalabad for qualitative, adulteration, and microbiological parameters and antimicrobial resistance of Escherichia coli. The mean ± standard deviation for each component was determined: Fat% (4.22 ± 0.78), Solid-Not-Fat (SNF)% (7.98 ± 1.19), Protein% (2.96 ± 0.50), Lactose% (4.49 ± 0.70), Density (25.59 ± 3.81 g mL−1), Salts% (0.66 ± 0.08), Added water% (8.56 ± 9.72), Temperature (28.00 ± 1.67), and Freezing point (−0.52 ± 0.72). Adulterants such as sodium chloride, detergent, formalin, urea, carbonate, and hydro-peroxide, along with high heterotrophic bacterial load, were detected. Antibiotic resistance profiling of E. coli strains exhibited resistance, including Multidrug-Resistant (MDR) strains. These findings highlight compromised microbiological and hygiene standards in locally sold unpacked milk in Faisalabad, necessitating urgent attention to ensure public health safety.

Evaluation of Pharmacokinetic and Pharmacodynamic (PK/PD) of Novel Fluorenylmethoxycarbonyl- Phenylalanine Antimicrobial Agent.

To assess the pharmacokinetic profile, in-vivo toxicity, and efficacy of 9-Fluorenylmethoxycarbonyl-L-phenylalanine (Fmoc-F) as a potential antibacterial agent, with a focus on its suitability for clinical translation. An RP-HPLC-based bio-analytical method was developed and qualified to quantify Fmoc-F levels in mouse plasma for pharmacokinetic analysis. Oral bioavailability was determined, and in-vivo toxicity was evaluated following intra-peritoneal administration. Efficacy was assessed by measuring the reduction in Staphylococcus aureus burden and survival rates in BALB/c mice. The RP-HPLC method is highly sensitive, detecting as low as 0.8µgmL-1 (~ 2µM) of Fmoc-F in blood plasma. This study revealed that Fmoc-F has an oral bioavailability of 65 ± 18% and suitable pharmacokinetic profile. Further, we showed that intra-peritoneal administration of Fmoc-F is well tolerated by BALB/c mice and Fmoc-F treatment (100mg/kg, i.p.) significantly reduces Staphylococcus aureus burden from visceral organs in BALB/c mice but falls short in enhancing survival rates at higher bacterial loads. The study provides crucial insights into the pharmacokinetic and pharmacodynamic properties of Fmoc-F. The compound displayed favourable oral bioavailability and in-vivo tolerance. Its significant reduction of bacterial burden underscores its potential as a treatment for systemic infections. However, limited effectiveness for severe infections, short half-life, and inflammatory response at higher doses need to be addressed for its clinical application.

IFNγ insufficiency during mouse intra-vaginal Chlamydia trachomatis infection exacerbates alternative activation in macrophages with compromised CD40 functions

Chlamydia trachomatis (C.tr), an obligate intracellular pathogen, causes asymptomatic genital infections in women and is a leading cause of preventable blindness. We have developed in vivo mouse models of acute and chronic C. trachomatis genital infection to explore the significance of macrophage-directed response in mediating immune activation/suppression. Our findings reveal that during chronic and repeated C. trachomatis infections, Th1 response is abated while Treg response is enhanced. Additionally, an increase in exhaustion (PD1, CTLA4) and anergic (Klrg3, Tim3) T cell markers is observed during chronic infection. We have also observed that M2 macrophages with low CD40 expression promote Th2 and Treg differentiation leading to sustained C. trachomatis genital infection. Macrophages infected with C. trachomatis or treated with supernatant of infected epithelial cells drive them to an M2 phenotype. C. trachomatis infection prevents the increase in CD40 expression as observed in western blots and flow cytometric analysis. Insufficient IFNγ, as observed during chronic infection, leads to incomplete clearance of bacteria and poor immune activation. C. trachomatis decapacitates IFNγ responsiveness in macrophages via hampering IFNγRI and IFNγRII expression which can be correlated with poor expression of MHC-II, CD40, iNOS and NO release even following IFNγ supplementation. M2 macrophages during C. trachomatis infection express low CD40 rendering immunosuppressive, Th2 and Treg differentiation which could not be reverted even by IFNγ supplementation. The alternative macrophages also harbour high bacterial load and are poor responders to IFNγ, thus promoting immunosuppression. In summary, C. trachomatis modulates the innate immune cells, attenuating the anti-chlamydial functions of T cells in a manner that involves decreased CD40 expression on macrophages.