Isolation and detection of bacterial species on mitis salivarius bacitracin agar from the plaque samples of caries active children.

BACKGROUND: In cariology studies, mitis-salivarius-bacitracin (MSB) agar has been commonly considered as the selective medium for Streptococcusmutans growth. The present study was the part of a funded project (a noninferiority randomized controlled trial) which compared the efficacy of a plant extract-based mouth rinse with that of a fluoride mouth rinse on the S.mutans counts of the children. AIM: This study aimed to identify the frequency of detection of S.mutans and nonstreptococcal bacterial species from the dental plaque of caries active children using a combined technique of anaerobic culture and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. SETTINGS AND METHODS: Caries-active children (8-12 years old) were enrolled from a pediatric dental outpatient department at a tertiary care hospital. From each participant, dental plaque samples were collected from carious surfaces under sterilized conditions and then subjected to anaerobic culture. After 48 h of incubation, the bacterial colonies were isolated by sub-culture and identified by the MALDI-TOF. RESULTS: In all, 13 different bacterial species were isolated from the MSB agar medium. Other than S.mutans species, colonies of bacterial species such as Veillonelladispar,Streptococcusanginosus, Veillonellaparvula, and Streptococcusgordonii were also frequently observed from the medium. CONCLUSIONS: The study concluded that several bacterial strains, both streptococcal and nonstreptococcal, could be isolated from the MSB agar medium; hence, this medium should no longer be considered selective medium for the culture of S.mutans in clinical and epidemiological studies.

High-level production of chitinase by multi-strategy combination optimization in Bacillus licheniformis.

In view of the extensive potential applications of chitinase (ChiA) in various fields such as agriculture, environmental protection, medicine, and biotechnology, the development of a high-yielding strain capable of producing chitinase with enhanced activity holds significant importance. The objective of this study was to utilize the extracellular chitinase from Bacillus thuringiensis as the target, and Bacillus licheniformis as the expression host to achieve heterologous expression of ChiA with enhanced activity. Initially, through structural analysis and molecular dynamics simulation, we identified key amino acids to improve the enzymatic performance of chitinase, and the specific activity of chitinase mutant D116N/E118N was 48% higher than that of the natural enzyme, with concomitant enhancements in thermostability and pH stability. Subsequently, the expression elements of ChiA(D116N/E118N) were screened and modified in Bacillus licheniformis, resulting in extracellular ChiA activity reached 89.31 U/mL. Further efforts involved the successful knockout of extracellular protease genes aprE, bprA and epr, along with the gene clusters involved in the synthesis of by-products such as bacitracin and lichenin from Bacillus licheniformis. This led to the development of a recombinant strain, DW2△abelA, which exhibited a remarkable improvement in chitinase activity, reaching 145.56 U/mL. To further improve chitinase activity, a chitinase expression frame was integrated into the genome of DW2△abelA, resulting in a significant increas to 180.26 U/mL. Optimization of fermentation conditions and medium components further boosted shake flask enzyme activity shake flask enzyme activity, achieving 200.28 U/mL, while scale-up fermentation experiments yielded an impressive enzyme activity of 338.79 U/mL. Through host genetic modification, expression optimization and fermentation optimization, a high-yielding ChiA strain was successfully constructed, which will provide a solid foundation for the extracellular production of ChiA.

Real-Time Biosynthetic Reaction Monitoring Informs the Mechanism of Action of Antibiotics.

The rapid spread of drug-resistant pathogens and the declining discovery of new antibiotics have created a global health crisis and heightened interest in the search for novel antibiotics. Beyond their discovery, elucidating mechanisms of action has necessitated new approaches, especially for antibiotics that interact with lipidic substrates and membrane proteins. Here, we develop a methodology for real-time reaction monitoring of the activities of two bacterial membrane phosphatases, UppP and PgpB. We then show how we can inhibit their activities using existing and newly discovered antibiotics such as bacitracin and teixobactin. Additionally, we found that the UppP dimer is stabilized by phosphatidylethanolamine, which, unexpectedly, enhanced the speed of substrate processing. Overall, our results demonstrate the potential of native mass spectrometry for real-time biosynthetic reaction monitoring of membrane enzymes, as well as their in situ inhibition and cofactor binding, to inform the mode of action of emerging antibiotics.

Assessing the Risk of Antimicrobial Resistant Enterococcal Infections in Humans Due to Bacitracin Usage in Poultry.

Bacitracin is an antimicrobial used in the feed or water of poultry in the U.S. for the prevention, treatment, and control of clostridial diseases such as necrotic enteritis. Concern has been raised that bacitracin can select for antimicrobial-resistant bacteria that can be transmitted to humans and subsequently cause disease that is more difficult to treat because of the resistance. The objective of the present study was to perform a quantitative risk assessment (QRA) to estimate the potential risk in the U.S. of human infection with antimicrobial-resistant Enterococcus faecalis and E. faecium derived from chicken and turkey products as a result of bacitracin usage in U.S. poultry. The modeling approach estimated the annual number of healthcare-associated enterococcal infections in the U.S. that would be resistant to antimicrobial therapy and that would be derived from poultry sources because of bacitracin use in poultry. Parameter estimates were developed to be "maximum risk" to overestimate the risk to humans. While approximately 60% of E. faecalis and E. faecium derived from poultry were predicted to possess bacitracin resistance based on the presence of the bcrABDR gene locus, very few human-derived isolates possessed this trait. Furthermore, no vancomycin or linezolid-resistant strains of E. faecalis or E. faecium were detected in poultry sources between the years 2002 and 2019. The model estimated the number of antimicrobial-resistant E. faecalis and E. faecium cases per year that might resist therapy due to bacitracin use in poultry as 0.86 and 0.14, respectively, which translates to an annual risk estimate for E. faecalis of less than 1 in 350 million and for E. faecium of less than 1 in 2 billion for members of the U.S. population. Even with the use of risk-maximizing assumptions, the results indicate that there is a high probability that the use of bacitracin according to label instructions in U.S. poultry presents a negligible risk to human health.

Comparison of Antibacterial Efficacy of Triple Antibiotic-Loaded Hydrogel Versus Modified Triple Antibiotic-Loaded Hydrogel as Intracanal Medicament Against Enterococcus faecalis: An In vitro Study.

OBJECTIVE: Triple antibiotic paste (TAP) is known to have an essential role in the success of endodontic treatment by eliminating pathogens from the root canal system. Unfortunately, it causes discolouration and cytotoxicity at high concentrations. The objective of this research was to assess and compare the antimicrobial effectiveness of various concentrations (1 mg, 5 mg, 10 mg) of TAP, TAP hydrogel (TAPH), M-TAP, and M-TAP hydrogel (MTAPH) against Enterococcus faecalis. METHODS: The agar well diffusion method was used to assess the antibiotic sensitivity of the following intracanal medicaments: TAP (ciprofloxacin, metronidazole, and minocycline) mixed in a ratio of 1: 1: 1; TAPH, M-TAP (ciprofloxacin, metronidazole, and amoxicillin), M-TAPH and plain hydrogel. Each tested medicament was individually evaluated for its antimicrobial activity against Enterococcus faecalis. Structural and topographical characterisation were analysed using a Scanning Electron Microscope (SEM) and interpreted using ImageJ software. A microdilution broth test was performed to examine the minimum inhibitory concentration and minimum bactericidal concentration (MBC) of M-TAP and TAP. RESULTS: Except for the plain hydrogel, M-TAP and hydrogel and TAP and hydrogel showed significantly varied inhibitory zones at different concentrations. M-TAPH showed the highest mean zone of inhibition of 21.6, 33.33 and 38.0 mm at a concentration of 1, 5, and 10 mg/mL when compared to TAPH, which showed a mean zone of inhibition of 3.3 mm,12.3 mm, 21.3 mm at the respective concentrations. The MIC study shows that more than 75% of Enterococcus faecalis growth was inhibited by M-TAP at a concentration of 5 µg/mL, whereas TAP showed inhibition at a concentration of 35 µg/mL. MBC results indicate that almost 99.9% of the bacterial population was killed at a concentration of 100 µg/mL (10-1) for TAP and 10 µg/mL (10-2) for M-TAP. CONCLUSION: The antibacterial efficacy of M-TAP was significantly higher than TAP. Application of M-TAP at lower doses is advised to overcome the disadvantages seen with TAP.

Investigating antibiotic free feed additives for growth promotion in poultry: effects on performance and microbiota.

The poultry industry is evolving towards antibiotic-free production to meet market demands and decelerate the increasing spread of the antimicrobial resistance. The growing need for antibiotic free products has challenged producers to decrease or completely stop using antimicrobials as feed supplements in broiler diet to improve feed efficiency, growth rate, and intestinal health. Natural feed additives (e.g., probiotics and phytobiotics) are promising alternatives to substitute antimicrobial growth promoters. The goal of our study was to characterize the effects of a Probiotic and an Essential Oils blend on broilers' performance and perform a time-series analysis to describe their excreta microbiome. A total of 320 Cobb 500 (1-day-old) chicks were raised for 21 d in 32 randomly allocated cages. Treatments consisted of 4 experimental diets: a basal diet, and a basal diet mixed with an Antibiotic (bacitracin methylene disalicylate), an essential oils blend (oregano oil, rosemary, and red pepper), or a Probiotic (Bacillus subtilis). Body weight (on 1, 10, and 21d), and feed intake (10d and 21d) were recorded and feed conversion ratio was calculated. Droppings were collected daily (1-21d) to characterize broilers' excreta microbiota by targeted sequencing of the bacterial 16S rRNA gene. The Probiotic significantly improved feed conversion ratio for starter phase 1 to 10d (P = 0.03), grower phase 10 to 21d (P = 0.05), and total period 1 to 21d (P = 0.01) compared to the Antibiotic. Feed supplements did not affect alpha diversity but did impact microbial beta diversity (P < 0.01). Age also impacted microbiome turnover as differences in alpha and beta diversity were detected. Furthermore, when compared to the basal diet, the probiotic and antibiotic significantly impacted relative abundance of Bifidobacterium (log2 fold change -1.44, P = 0.03), Intestinimonas (log2 fold change 0.560, P < 0.01) and Ligilactobacillus (log2 fold change -1.600, P < 0.01). Overall, Probiotic supplementation but not essential oils supplementation positively impacted broilers' growth performance by directly causing directional shifts in broilers' excreta microbiota structure.

Bacitracin agar vs. oleandomycin disk supplemented chocolate agar for the recovery of Haemophilus influenzae in diagnostic samples: A prospective comparison.

Haemophilus influenzae is an important pathogen able to cause various forms of respiratory and invasive disease. To provide high sensitivity for detection, culture media must inhibit growth of residential flora from the respiratory tract. This study aimed to identify and compare the diagnostic and economic advantages of using bacitracin containing selective agar (SEL) or oleandomycin disk supplemented chocolate agar (CHOC). Growth and semi-quantitative abundance of H. influenzae and growth suppression of residential flora was prospectively assessed in a 28-week period. H. influenzae was identified in 164 (5 %) of all included samples: CHOC and SEL, CHOC only, and SEL only were positive in 95, 24, and 45 cases. Diagnostic superiority of SEL was primarily attributable to the results of throat swabs. However, on average, € 200 had to be spent for the detection of each additional isolate that was recovered only because of additional incubation on SEL.

The Bacillus subtilis cell envelope stress-inducible ytpAB operon modulates membrane properties and contributes to bacitracin resistance.

Antibiotics that inhibit peptidoglycan synthesis trigger the activation of both specific and general protective responses. σM responds to diverse antibiotics that inhibit cell wall synthesis. Here, we demonstrate that cell wall-inhibiting drugs, such as bacitracin and cefuroxime, induce the σM-dependent ytpAB operon. YtpA is a predicted hydrolase previously proposed to generate the putative lysophospholipid antibiotic bacilysocin (lysophosphatidylglycerol), and YtpB is the branchpoint enzyme for the synthesis of membrane-localized C35 terpenoids. Using targeted lipidomics, we reveal that YtpA is not required for the production of lysophosphatidylglycerol. Nevertheless, ytpA was critical for growth in a mutant strain defective for homeoviscous adaptation due to a lack of genes for the synthesis of branched chain fatty acids and the Des phospholipid desaturase. Consistently, overexpression of ytpA increased membrane fluidity as monitored by fluorescence anisotropy. The ytpA gene contributes to bacitracin resistance in mutants additionally lacking the bceAB or bcrC genes, which directly mediate bacitracin resistance. These epistatic interactions support a model in which σM-dependent induction of the ytpAB operon helps cells tolerate bacitracin stress, either by facilitating the flipping of the undecaprenyl phosphate carrier lipid or by impacting the assembly or function of membrane-associated complexes involved in cell wall homeostasis.IMPORTANCEPeptidoglycan synthesis inhibitors include some of our most important antibiotics. In Bacillus subtilis, peptidoglycan synthesis inhibitors induce the σM regulon, which is critical for intrinsic antibiotic resistance. The σM-dependent ytpAB operon encodes a predicted hydrolase (YtpA) and the enzyme that initiates the synthesis of C35 terpenoids (YtpB). Our results suggest that YtpA is critical in cells defective in homeoviscous adaptation. Furthermore, we find that YtpA functions cooperatively with the BceAB and BcrC proteins in conferring intrinsic resistance to bacitracin, a peptide antibiotic that binds tightly to the undecaprenyl-pyrophosphate lipid carrier that sustains peptidoglycan synthesis.

Outcomes After Implant-Based Breast Reconstruction Following the National Institution of a Ban on Bacitracin Irrigation.

BACKGROUND: The use of irrigation with bacitracin-containing solution is common among surgeons, as it was widely thought to have antibacterial properties and prevent postoperative infection. Current literature, however, suggests that antibiotic-containing irrigation confers little added benefit. On January 31, 2020, the Food and Drug Administration instituted a ban on bacitracin-containing irrigation for operative use. This study aimed to determine whether bacitracin has a beneficial effect on postoperative infection rates by analyzing infection rates before and after the Food and Drug Administration ban on bacitracin irrigation. METHODS: A single-institution retrospective chart review was conducted. Eligible patients underwent implant-based breast reconstruction after mastectomy from October 1, 2016, to July 31, 2022. Procedure date, reconstruction type, patient comorbidities, use of bacitracin irrigation, postoperative infection, and secondary outcomes were collected. Univariate and multivariable logistic regression analyses were performed. RESULTS: A total of 188 female patients were included in the study. Bacitracin use did not protect against infection in univariate or multivariable analysis. Age greater than 50 years was associated with an increased risk of postoperative infection ( P = 0.0366). The presence of comorbidities, smoker status, neoadjuvant therapy treatment before surgery, implant placement, and laterality were all not significantly associated with postoperative infection development. CONCLUSIONS: The results of this study demonstrate a lack of association between bacitracin use and postoperative infection. Additional research into the optimal antibiotic for perioperative irrigation is needed, as bacitracin is not encouraged for use.

Development of an environmentally sensitive fluorescent peptide probe for MrgX2 and application in ligand screening of peptide antibiotics.

Mast cells (MCs) are primary effector cells involved in immediate allergic reactions. Mas-related G protein-coupled receptor-X2 (MrgX2), which is highly expressed on MCs, is involved in receptor-mediated drug-induced pseudo-anaphylaxis. Many small-molecule drugs and peptides activate MrgX2, resulting in MC activation and allergic reactions. Although small-molecule drugs can be identified using existing MrgX2 ligand-screening systems, there is still a lack of effective means to screen peptide ligands. In this study, to screen for peptide drugs, the MrgX2 high-affinity endogenous peptide ligand substance P (SP) was used as a recognition group to design a fluorescent peptide probe. Spectroscopic properties and fluorescence imaging of the probe were assessed. The probe was then used to screen for MrgX2 agonists among peptide antibiotics. In addition, the effects of peptide antibiotics on MrgX2 activation were investigated in vivo and in vitro. The environment-sensitive property of the probe was revealed by the dramatic increase in fluorescence intensity after binding to the hydrophobic ligand-binding domain of MrgX2. Based on these characteristics, it can be used for in situ selective visualization of MrgX2 in live cells. The probe was used to screen ten types of peptide antibiotics, and we found that caspofungin and bacitracin could compete with the probe and are hence potential ligands of MrgX2. Pharmacological experiments confirmed this hypothesis; caspofungin and bacitracin activated MCs via MrgX2 in vitro and induced local anaphylaxis in mice. Our research can be expected to provide new ideas for screening MrgX2 peptide ligands and reveal the mechanisms of adverse reactions caused by peptide drugs, thereby laying the foundation for improving their clinical safety.

Antimicrobial susceptibility of U.S. porcine Brachyspira isolates and genetic diversity of B. hyodysenteriae by multilocus sequence typing.

Swine dysentery, caused by Brachyspira hyodysenteriae and the newly recognized Brachyspira hampsonii in grower-finisher pigs, is a substantial economic burden in many swine-rearing countries. Antimicrobial therapy is the only commercially available measure to control and prevent Brachyspira-related colitis. However, data on antimicrobial susceptibility trends and genetic diversity of Brachyspira species from North America is limited. We evaluated the antimicrobial susceptibility profiles of U.S. Brachyspira isolates recovered between 2013 and 2022 to tiamulin, tylvalosin, lincomycin, doxycycline, bacitracin, and tylosin. In addition, we performed multilocus sequence typing (MLST) on 64 B. hyodysenteriae isolates. Overall, no distinct alterations in the susceptibility patterns over time were observed among Brachyspira species. However, resistance to the commonly used antimicrobials was seen sporadically with a higher resistance frequency to tylosin compared to other tested drugs. B. hampsonii was more susceptible to the tested drugs than B. hyodysenteriae and B. pilosicoli. MLST revealed 16 different sequence types (STs) among the 64 B. hyodysenteriae isolates tested, of which 5 STs were previously known, whereas 11 were novel. Most isolates belonged to the known STs: ST93 (n = 32) and ST107 (n = 13). Our findings indicate an overall low prevalence of resistance to clinically important antimicrobials other than tylosin and bacitracin, and high genetic diversity among the clinical Brachyspira isolates from pigs in the United States during the past decade. Further molecular, epidemiologic, and surveillance studies are needed to better understand the infection dynamics of Brachyspira on swine farms and to help develop effective control measures.

Bacitracin enhances ceftriaxone susceptibility of the high-level ceftriaxone-resistant gonococcal FC428 clone.

IMPORTANCE: Ceftriaxone-based antimicrobial therapies for gonorrhea are threatened by waning ceftriaxone susceptibility levels and the global dissemination of the high-level ceftriaxone-resistant gonococcal FC428 clone. Combination therapy can be an effective strategy to restrain the development of ceftriaxone resistance, and for that purpose, it is important to find an alternative antimicrobial to replace azithromycin, which has recently been removed in some countries from the recommended ceftriaxone plus azithromycin dual-antimicrobial therapy. Ideally, the second antimicrobial should display synergistic activity with ceftriaxone. We hypothesized that bacitracin might display synergistic activity with ceftriaxone because of their distinct mechanisms targeting bacterial cell wall synthesis. In this study, we showed that bacitracin indeed displays synergistic activity with ceftriaxone against Neisseria gonorrhoeae. Importantly, strains associated with the FC428 clone appeared to be particularly susceptible to the bacitracin plus ceftriaxone combination, which might therefore be an interesting dual therapy for further in vivo testing.

New insights into the Undecaprenol monophosphate recycling pathway of Streptococcus pneumoniae.

Recycling of undecaprenol pyrophosphate is critical to regenerate the pool of undecaprenol monophosphate required for cell wall biosynthesis. Undecaprenol pyrophosphate is dephosphorylated by membrane-associated undecaprenyl pyrophosphate phosphatases such as UppP or type 2 Phosphatidic Acid Phosphatases (PAP2) and then transferred across the cytoplasmic membrane by Und-P flippases such as PopT (DUF368-containing protein) or UptA (a DedA family protein). While the deletion of uppP in S. pneumoniae has been reported to increase susceptibility to bacitracin and reduce infectivity in a murine infection model, the presence of PAP2 family proteins or Und-P flippases and their potential interplay with UppP in S. pneumoniae remained unknown. In this report, we identified two PAP2 family proteins and a DUF368-containing protein and investigated their roles together with that of UppP in cell growth, cell morphology and susceptibility to bacitracin in S. pneumoniae. Our results suggest that the undecaprenol monophosphate recycling pathway in S. pneumoniae could result from a functional redundancy between UppP, the PAP2-family protein Spr0434 and the DUF368-containing protein Spr0889.

pH-Triggered visual detection of Escherichia coli based on the co-assembly of bacitracin and thymolphthalein.

A novel probe for bacteria was simply synthesized through the solvent-induced co-assembly of bacitracin (AMP) and thymolphthalein (TP) without complicated modification. Combining with aptamer-Fe3O4, AMP/TP nanoparticles were used for the colorimetric detection of Escherichia coli with good sensitivity through the NaOH-triggered blue color and a smartphone-based App.

Identification of DraRS in Clostridioides difficile, a Two-Component Regulatory System That Responds to Lipid II-Interacting Antibiotics.

Clostridioides difficile is a Gram-positive opportunistic pathogen that results in 220,000 infections, 12,000 deaths, and upwards of $1 billion in medical costs in the United States each year. C. difficile is highly resistant to a variety of antibiotics, but we have a poor understanding of how C. difficile senses and responds to antibiotic stress and how such sensory systems affect clinical outcomes. We have identified a spontaneous C. difficile mutant that displays increased daptomycin resistance. We performed whole-genome sequencing and found a nonsense mutation, S605*, in draS, which encodes a putative sensor histidine kinase of a two-component system (TCS). The draSS605* mutant has an ~4- to 8-fold increase in the daptomycin MIC compared to the wild type (WT). We found that the expression of constitutively active DraRD54E in the WT increases daptomycin resistance 8- to 16-fold and increases bacitracin resistance ~4-fold. We found that a selection of lipid II-inhibiting compounds leads to the increased activity of the luciferase-based reporter PdraR-slucopt, including vancomycin, bacitracin, ramoplanin, and daptomycin. Using RNA sequencing (RNA-seq), we identified the DraRS regulon. Interestingly, we found that DraRS can induce the expression of the previously identified hex locus required for the synthesis of a novel glycolipid produced in C. difficile. Our data suggest that the induction of the hex locus by DraR explains some, but not all, of the DraR-induced daptomycin and bacitracin resistance. IMPORTANCE Clostridioides difficile is a major cause of hospital-acquired diarrhea and represents an urgent concern due to the prevalence of antibiotic resistance and the rate of recurrent infections. C. difficile encodes ~50 annotated two-component systems (TCSs); however, only a few have been studied. The function of these unstudied TCSs is not known. Here, we show that the TCS DraRS plays a role in responding to a subset of lipid II-inhibiting antibiotics and mediates resistance to daptomycin and bacitracin in part by inducing the expression of the recently identified hex locus, which encodes enzymes required for the production of a novel glycolipid in C. difficile.

Probing the mechanism of reduced in vivo potency of insulin detemir.

BACKGROUND: Insulin detemir (IDet) is an insulin analog used to treat diabetes. IDet shows full efficacy but reduced potency compared to human insulin (HI) in both man and rat. In contrast, in pigs and dogs, IDet appears to have full in vivo potency. Non-receptor mediated degradation (NRMD) has previously been suggested as an explanation for the low potency of IDet, but this hypothesis has not been investigated further until now. Bacitracin is a nonspecific protease inhibitor which we hypothesized could inhibit NRMD of IDet in rats. RESEARCH DESIGN AND METHODS: Healthy male rats instrumented with permanent catheters underwent euglycemic clamp during constant infusion of either HI or IDet at effect-matched doses with co-infusion of vehicle or bacitracin. RESULTS: Plasma concentrations of IDet increased significantly (p < 0.005) during bacitracin compared to vehicle co-infusion and the concomitant increase in glucose infusion rate (GIR, p < 0.001) required to maintain euglycemic clamp indicates that the IDet rescued from NRMD indeed was active. No significant differences were detected with co-infusions of HI with either bacitracin or vehicle. CONCLUSIONS: A large proportion of NRMD of IDet which can be inhibited by bacitracin may partly explain the reduced potency of IDet observed in rats and likely also in man.

Microbial community and antibiotic resistance gene distribution in food waste, anaerobic digestate, and paddy soil.

The study assessed the occurrence and distribution of microbial community and antibiotic resistance genes (ARGs) in food waste, anaerobic digestate, and paddy soil samples, and revealed the potential hosts of ARGs and factors influencing their distribution. A total of 24 bacterial phyla were identified, of which 16 were shared by all samples, with Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria accounting for 65.9-92.3 % of the total bacterial community. Firmicutes was the most abundant bacteria in food waste and digestate samples, accounting for 33-83 % of the total microbial community. However, in paddy soil samples with digestate, Proteobacteria had the highest relative abundance of 38-60 %. Further, 22 ARGs were detected in food waste and digestate samples, with multidrug, macrolide-lincosamide-streptogramin (MLS), bacitracin, aminoglycoside, tetracycline, vancomycin, sulfonamide, and rifamycin resistance genes being the most abundant and shared by all samples. The highest total relative abundance of ARGs in food waste, digestate, and soil without and with digestate was detected in samples from January 2020, May 2020, October 2019, and May 2020, respectively. The MLS, vancomycin, tetracycline, aminoglycoside, and sulfonamide resistance genes had higher relative abundance in food waste and anaerobic digestate samples, whereas multidrug, bacteriocin, quinolone, and rifampin resistance genes were more abundant in paddy soil samples. Redundancy analysis demonstrated that aminoglycoside, tetracycline, sulfonamide, and rifamycin resistance genes were positively correlated with total ammonia nitrogen and pH of food waste and digestate samples. Vancomycin, multidrug, bacitracin, and fosmidomycin resistance genes had positive correlations with potassium, moisture, and organic matter in soil samples. The co-occurrence of ARG subtypes with bacterial genera was investigated using network analysis. Actinobacteria, Proteobacteria, Bacteroidetes, and Acidobacteria were identified as potential hosts of multidrug resistance genes.

Comparative effects of benzoic acid and sodium benzoate in diets for nursery pigs on growth performance and acidification of digesta and urine.

The objective of this study was to evaluate the comparative effects of benzoic acid and sodium benzoate in feeds on digesta pH, urinary pH, and growth performance for nursery pigs. A total of 432 pigs (6.9 ±â€…0.9 kg BW) were assigned to eight treatments (6 pigs per pen, replication = 9) in a randomized complete block design with initial body weight (BW) as a block and fed for 41 d in three phases (7/17/17 d, respectively). Treatments were 1) a basal diet (NC), 2) NC + 0.25% bacitracin methylene disalicylate (antibiotic; bacitracin: 250 g/t feed; PC), 3) NC + 0.25% benzoic acid, 4) NC + 0.35% benzoic acid, 5) NC + 0.50% benzoic acid, 6) NC + 0.30% sodium benzoate, 7) NC + 0.40% sodium benzoate, and 8) NC + 0.60% sodium benzoate. Growth performance and fecal scores were measured for each phase. One gilt representing the median BW of each pen was euthanized to collect digesta from the stomach, proximal jejunum, distal jejunum, and cecum, and urine. The PC tended to improve average daily gain (ADG) in phase 1 (P = 0.052) and phase 2 (P = 0.093) as well as average daily feed intake (ADFI) in phase 2 (P = 0.052). Overall, increasing supplemental benzoic acid tended to have a quadratic effect on ADG (P = 0.094), but no difference in ADFI was observed. Increasing supplemental sodium benzoate showed a quadratic effect (P < 0.05) on ADG and linearly increased (P < 0.05) ADFI. Urinary pH linearly decreased (P < 0.05) with increasing supplemental benzoic acid, but was not affected by supplemental sodium benzoate. Increasing supplemental benzoic acid or sodium benzoate linearly increased (P < 0.05) benzoic acid content in digesta of the stomach. Increasing supplemental benzoic acid or sodium benzoate also linearly increased (P < 0.05) urinary hippuric acid. However, the PC did not decrease urinary pH or increase urinary benzoic acid and hippuric acid. With slope-ratio assay using ADG and urinary hippuric acid as dependent variables and benzoic acid intake as an independent variable, the relative bioavailability of benzoic acid compared to sodium benzoate was not different. In conclusion, supplementation of benzoic acid and sodium benzoate could improve the growth performance of nursery pigs. The relative bioavailability of sodium benzoate to benzoic acid of nursery pigs did not differ based on BW gain and urinary hippuric acid.

Newly weaned pigs are exposed to various challenges during the postweaning period, resulting in retarded growth performance. Dietary antibiotics have been used to reduce the negative impacts of weaning stress. However, use of antibiotics in feeds has been phased out in response to concerns associated with microbial resistance. In this study, dietary benzoic acid was supplemented to promote growth performance and increase urinary hippuric acid of nursery pigs. The sodium benzoate may show similar effects with benzoic acid on growth performance and urinary hippuric acid, as sodium benzoate can be highly converted to benzoic acid via the action of gastric acid in stomach. Thus, this study aimed to investigate the effects of increasing benzoic acid and sodium benzoate supplementation on growth performance and acidification of digesta and urine, and to investigate the comparative effects of benzoic acid and sodium benzoate supplemented in diets for nursery pigs. Dietary benzoic acid and sodium benzoate improved body weight gain and increased urinary hippuric acid of nursery pigs. Both sodium benzoate and benzoic acid had similar effects when fed to nursery pigs for their body weight gain and metabolism. Benzoic acid, however, had a stronger effect acidifying urine compared with sodium benzoate.

Application of chromogenic media for preliminary identification of acid-resistant bacteria.

Background: The variety of morphological and cultural characteristics of acid-resistant bacteria (ARB) makes it possible to use microscopy and estimate the growth rate and pigment formation when cultivating on solid egg media for preliminary identification only as additional indicative methods. It is necessary to develop new approaches for the cultivation and primary identification of ARB isolated from the biological material. It will allow to obtain data on the prevalence, structure, epidemiological, and clinical features of infectious processes caused by opportunistic ARB. Methods: Three hundred and sixty strains of ARB were isolated from the various biological materials obtained from the patients during the examination for tuberculosis. All biological material samples were negative on Mycobacteria tuberculosis complex. Species identification of all bacteria was performed by matrix-assisted lazer desorption/ion-ization time-of-flight mass spectrometry. The cultural characteristics of ARB were evaluated on a universal chromogenic media. As a selective additive, a mixture of bacitracin and polymyxin sulfate which had no effect on ARB was tested to suppress concomitant Gram-positive and Gram-negative microflora. Results: Cultural characteristics were identified and described for all tested representatives of fast-growing nontuberculous mycobacteria (NTM), as well as for all types of nocardia, gordonia, and streptomycetes. Representatives of other genera of ARB on a universal chromogenic media gave meager growth or did not show it at all. When inoculated on a universal chromogenic media with a selective addition, 100% of the strains from the ARB group showed abundant or moderate growth. Incubation time for fast-growing species was up to 7 days; for slow-growing species, it was up to 28 days. Concomitant control strains of Gram-positive and Gram-negative bacteria on universal chromogenic media with selective growth additive did not show the growth. Conclusions: The use of a universal chromogenic media allows to preliminarily identify NTM and other ARB by cultural characteristics. The addition of bacitracin and polymyxin sulfate does not reduce the growth properties of ARB, which can be used when working with both biological materials and for the isolation of pure ARB cultures from mixtures with other bacteria.

An Appraisal of pH triggered Bacitracin drug release, through composite hydrogel systems.

Comparative investigations on environmentally triggered drug delivery and wound healing characteristics of flexible hydrogel composites, Chitosan-Gelatin (C/G) and 2-Hydroxyethyl Methacrylate-Gelatin (H/G); are presented here. These composites, prepared through facile synthesis and curing methods, indicate the potential to smartly respond to the pH changes in wounds by releasing drug simultaneously and aiding in faster healing. An in-vitro investigation of the composite characteristics were included testing for Equilibrium Water Capacity Studies, Fourier Transform Infrared Spectroscopy (FTIR) investigations as well as UV based drug release and gravimetric hydrogel degradation profiles. This was followed by cutaneous application testing of the hydrogel systems in balb-c mice. Observations and testing results indicated the potential applicability of the hydrogel systems as dressings for topical/transdermal applications, provided that further detailed in-vivo characteristics are accounted for.