Absence Of Antibiotics Research Articles

In vivo acquisition of blaKPC-2 with low biological cost in blaAFM-1-harboring ST463 hypervirulent Pseudomonas aeruginosa from a patient with hematologic malignancy

Klebsiella pneumoniae carbapenemase (KPC)-producing sequence type (ST) 463 Pseudomonas aeruginosa are increasingly prevalent in China. This study aims to investigate how blaKPC-2 is acquired in ST463 P. aeruginosa during antimicrobial therapy. Two extensively drug-resistant P. aeruginosa strains, B1122 and U1121, were respectively isolated from blood and urine of a patient during carbapenem therapy. Whole-genome sequences were obtained, and minimum inhibitory concentrations (MICs) were determined. Plasmid transferability and stability were examined. Bacterial growth kinetics, biofilm formation, and virulence level was assessed. U1121 and B1122 were only susceptible to amikacin and intermediately susceptible to colistin. They were isogenic ST463 P. aeruginosa strains and shared the same chromosome-encoded resistance genes, including blaAFM-1. This is the first report of chromosomal integration of blaAFM-1 in P. aeruginosa mediated by ISCR29. pU1121 and pB1122, which shared almost identical backbone, were the sole plasmids in U1121 and B1122, respectively, differing by an insertion region containing two copies of blaKPC-2 genes observed on pU1121. Sequence alignment revealed that pU1121 might evolve in vivo from pB1122 via IS26-mediated continuous genetic rearrangement in response to selective challenge from carbapenem. pU1121 was not self-transmissible and could be stably maintained in the host in the absence of antibiotic. Both U1121 and B1122 were hypervirulent, and no differences on virulence were recorded between them. However, U1121 exhibited significant impaired growth in comparison with B1122. ST463 P. aeruginosa can capture blaKPC-2 through horizontal transfer of insertion sequence under antibiotic selection pressure, which does decrease the fitness but does not impair the virulence of the ancestor.

Investigating the need for antibiotic supplementation to the extender used for semen cryopreservation in collared peccaries

The objective was to investigate the effects of semen freezing extender supplementation with antibiotics on bacterial load of semen samples, sperm functional and morphological metrics in the collared peccary. Fresh ejaculates from 10 males were extended in Tris-egg yolk-glycerol supplemented or not (control) with gentamicin (70 μg/mL) streptomycin-penicillin (SP; 1 mg/mL−1000 IU/mL) or and cryopreserved in liquid nitrogen. Bacterial load, sperm motility patterns, morphology, membrane functionality and integrity, mitochondrial activity, chromatin integrity and sperm-binding ability were evaluated in fresh and frozen-thawed samples. Regardless of the use of antibiotics, the sole cryopreservation provoked a significant decrease (P < 0.05) in bacterial load compared to fresh samples (from average values > 1 x 106 CFU/mL to <0.4 × 106 CFU/mL). Post-thawing sperm kinetic parameters were not affected by the absence or presence of different antibiotics, except for beat cross frequency that was significantly (P < 0.05) impaired by SP supplementation compared to the group without antibiotics. After thawing, sperm morphology, membrane functionality and integrity, and mitochondrial activity were also not affected by the presence or absence of antibiotics; however, a significant decrease was observed in the group without antibiotics (P < 0.05) in comparison to fresh samples. Regarding sperm-binding ability, there were no differences among the different groups. While collared peccary semen could be efficiently cryopreserved in the absence of antibiotics in the extender, the use of both gentamicin or the streptomycin-penicillin combination is recommended as effective antibiotic supplementation for a further control of bacterial loads without affecting sperm parameters.

199. A novel and scalable antimicrobial surface modification technology to prevent and mitigate implant related surgical site infections: an in-vivo safety and efficacy study

<h3>BACKGROUND CONTEXT</h3> Despite significant technological advancements in material science, a high level of hand-hygiene and systematic use of antiseptics and antibiotics, surgical site infections (SSI) are still to date the number one complication seen after surgery in the United States. Methicillin-resistant Staphylococcus aureus (MRSA) is the largest purveyor of health care-acquired infections (HCAI) and is responsible for significant morbidity and mortality. <h3>PURPOSE</h3> This study aimed to demonstrate the in-vivo safety and antibacterial efficacy of non-eluting titanium implants covalently bound with a novel broad-spectrum biocidal quaternary ammonium compound (DBG21) against MRSA biofilm. <h3>STUDY DESIGN/SETTING</h3> Subcutaneous MRSA infection mouse model comparing the antimicrobial efficacy of untreatedversusDBG21-treated titanium alloy discs. A separate comparative safety study was performed in the absence of infection. <h3>PATIENT SAMPLE</h3> Sixty-five 11-week-old balb/c mice. <h3>OUTCOME MEASURES</h3> Efficacy study: Number of adherent bacteria on implants (CFU) and in the surrounding tissue (CFU/g) at days 7 and 14. Safety study: systemic and subacute toxicity (clinical tolerance, blood tests and histology). <h3>METHODS</h3> Efficacy Study: TiAl6V4 discs, 6mm ø, 0.5 mm thick, were activated, dip-coated in a polymer solution, and baked to produce covalently bound DBG21-treated discs. Untreated TiAl6V4 discs were used as controls. All discs underwent subsequent sterilization by 25kGy gamma-irradiation, were implanted either untreated for control mice or DBG21-treated for treated mice, and were challenged with a high-bacterial inoculum of MRSA (ATCC43300) in a well-established subcutaneous infection mouse model (11-week-old balb/c) in the absence of antibiotics. A veterinary ethics committee validated the protocol. Sixty-five mice (33 controls, 32 treated) were included in an antibacterial efficacy study. After implantation of one disc in a posterior subcutaneous pocket and closure of the skin for each mouse, 7 log10CFU (colony forming units) of MRSA were injected through a catheter into the operating site. Mice were sacrificed after either 7 days (18 treated, 18 controls) or 14 days (15 controls, 14 treated) to determine the number of adherent bacteria (biofilm) on implants and in the peri-implant surrounding tissues. Results were expressed respectively as median log10CFU reduction on implants and median log10CFU/g reduction in tissue compared with untreated control mice. The statistical significance (p) was determined using Mann-Whitney tests. Safety Study: Ten mice implanted with either control (5 mice) or DBG-21 treated (5 mice) discs were assessed in a safety study in the absence of infection (ISO 10993-11:2017 for systemic and subacute toxicity including clinical tolerance, blood tests and local histology). <h3>RESULTS</h3> Efficacy Study: At both 7 and 14 days, DBG21-treated implants yielded a significant decrease in MRSA biofilm (respectively 3.6 median log10CFU (99.97%) reduction (p < 0.001) and 1.9 median log10CFU (98.7%) reduction (p = 0.037)) and peri-implant surrounding tissues (respectively 2.7 median log10CFU/g (99.8%) reduction (p < 0.001) and 5.6 median log10CFU/g (99.9997%) reduction (p < 0.001)). At day 7, three treated mice (16.6%) were completely sterilized on both tissue and implant. At day 14, 10 treated mice (71.4%) had sterile peri-implant tissue. Safety Study: There were no significant differences between control and treated mice in terms of clinical scores, blood tests and local histology after up to 11 days from implantation. <h3>CONCLUSIONS</h3> Preventing biofilm formation has been recognized as a key element of SSI prevention. Yet, no biofilm-resistant titanium implants are available in clinical practice to prevent and mitigate the burden of SSIs. This small animal safety and efficacy trial suggests that DBG-21 is a promising candidate for antimicrobial surface modification of titanium implants. <h3>FDA DEVICE/DRUG STATUS</h3> DBG21 antimicrobial surface modification (Not approved for this indication).

Antibiotics Drive Expansion of Rare Pathogens in a Chronic Infection Microbiome Model.

ABSTRACTChronic (long-lasting) infections are globally a major and rising cause of morbidity and mortality. Unlike typical acute infections, chronic infections are ecologically diverse, characterized by the presence of a polymicrobial mix of opportunistic pathogens and human-associated commensals. To address the challenge of chronic infection microbiomes, we focus on a particularly well-characterized disease, cystic fibrosis (CF), where polymicrobial lung infections persist for decades despite frequent exposure to antibiotics. Epidemiological analyses point to conflicting results on the benefits of antibiotic treatment yet are confounded by the dependency of antibiotic exposures on prior pathogen presence, limiting their ability to draw causal inferences on the relationships between antibiotic exposure and pathogen dynamics. To address this limitation, we develop a synthetic infection microbiome model representing CF metacommunity diversity and benchmark on clinical data. We show that in the absence of antibiotics, replicate microbiome structures in a synthetic sputum medium are highly repeatable and dominated by oral commensals. In contrast, challenge with physiologically relevant antibiotic doses leads to substantial community perturbation characterized by multiple alternate pathogen-dominant states and enrichment of drug-resistant species. These results provide evidence that antibiotics can drive the expansion (via competitive release) of previously rare opportunistic pathogens and offer a path toward microbiome-informed conditional treatment strategies.IMPORTANCE We develop and clinically benchmark an experimental model of the cystic fibrosis (CF) lung infection microbiome to investigate the impacts of antibiotic exposures on chronic, polymicrobial infections. We show that a single experimental model defined by metacommunity data can partially recapitulate the diversity of individual microbiome states observed across a population of people with CF. In the absence of antibiotics, we see highly repeatable community structures, dominated by oral microbes. Under clinically relevant antibiotic exposures, we see diverse and frequently pathogen-dominated communities, and a nonevolutionary enrichment of antimicrobial resistance on the community scale, mediated by competitive release. The results highlight the potential importance of nonevolutionary (community-ecological) processes in driving the growing global crisis of increasing antibiotic resistance.

Bactericidal and anti-biofilm effects of uncharged and cationic ultrasound-responsive nitric oxide microbubbles on Pseudomonas aeruginosa biofilms

Bacterial biofilms are a major and ongoing concern for public health, featuring both inherited genetic resistance traits and a conferred innate tolerance to traditional antibiotic therapies. Consequently, there is a growing need for novel methods of drug delivery, to increase the efficacy of antimicrobial agents. This research evaluated the anti-biofilm and bactericidal effects of ultrasound responsive gas-microbubbles (MBs) of either air or nitric oxide, using an in vitro Pseudomonas aeruginosa biofilm model grown in artificial wound medium. The four lipid-based MB formulations evaluated were room-air MBs (RAMBs) and nitric oxide MBs (NOMBs) with no electrical charge, as well as cationic (+) RAMBs+ and NOMBs+. Two principal treatment conditions were used: i) ultrasound stimulated MBs only, and ii) ultrasound stimulated MBs with a sub-inhibitory concentration (4 µg/mL) of the antibiotic gentamicin. The total treatment time was divided into a 60 second passive MB interaction period prior to 40 second ultrasound exposure; each MB formulation was tested in triplicate. Ultrasound stimulated RAMBs and NOMBs without antibiotic achieved reductions in biofilm biomass of 93.3% and 94.0%, respectively. Their bactericidal efficacy however was limited, with a reduction in culturable cells of 26.9% and 65.3%, respectively. NOMBs with sub-inhibitory antibiotic produced the most significant reduction in biofilm biomass, corresponding to a 99.9% (SD ± 5.21%); and a 99.9% (SD ± 0.07%) (3-log) reduction in culturable bacterial cells. Cationic MBs were initially manufactured to promote binding of MBs to negatively charged biofilms, but these formulations also demonstrated intrinsic bactericidal properties. In the absence of antibiotic, the bactericidal efficacy of RAMB+ and NOMB+ was greater that of uncharged counterparts, reducing culturable cells by 84.7% and 86.1% respectively; increasing to 99.8% when combined with antibiotic. This study thus demonstrates the anti-biofilm and bactericidal utility of ultrasound stimulated MBs, and specifically is the first to demonstrate the efficacy of a NOMB for the dispersal and potentiation of antibiotics against bacterial biofilms in vitro. Importantly the biofilm system and complex growth-medium were selected to recapitulate key morphological features of in vivo biofilms. The results us offer new insight for the development of new clinical treatments, for example, in chronic wounds.

Comparative impact of conventional and alternative gut health management programs on gastrointestinal responses in broiler chickens raised in commercial and research settings

Gut health management programs are developed to support growth performance and livability of broiler chickens reared in the absence of antibiotics. Identifying the impact of gut health management programs on gastrointestinal responses would improve the understanding of how the gastrointestinal tract ( GIT ) and associated structures are affected in the absence of antibiotics. The objective of this study was to evaluate the effect of commercial gut health management programs on visceral organ weight, jejunal histomorphology, and concentration of cecal digesta short chain fatty acids ( SCFA ) in broiler chickens reared under commercial (study 1) and research settings (study 2). Broiler chickens were reared on one of 3 gut health management programs: 1) conventional ( CON ), 2) raised without medically important antimicrobials ( RWMIA ), and 3) raised without antibiotics ( RWA ). Studies showed no statistical differences for d 28 body weight, relative spleen weight, or villus height. Both studies showed lower relative liver weight in birds reared on the CON program compared to the other programs ( P ≤ 0.04). A greater crypt depth ( CD ) and a lower villus height to crypt depth ratio ( VH:CD ) was observed in RWA compared to CON under research settings (study 2). Gut health management program influenced ceca SCFA concentration on d 28 under research settings with CON birds exhibiting higher concentration of acetic, propionic, butyric, and total SCFA than birds reared on the RWA program. Results suggest that broiler chickens reared on conventional and alternative gut health management programs showed some differences in organ weight, intestinal morphology, and cecal SCFA profile.

Expression of Bacillus subtilis ABCF antibiotic resistance factor VmlR is regulated by RNA polymerase pausing, transcription attenuation, translation attenuation and (p)ppGpp.

Since antibiotic resistance is often associated with a fitness cost, bacteria employ multi-layered regulatory mechanisms to ensure that expression of resistance factors is restricted to times of antibiotic challenge. In Bacillus subtilis, the chromosomally-encoded ABCF ATPase VmlR confers resistance to pleuromutilin, lincosamide and type A streptogramin translation inhibitors. Here we show that vmlR expression is regulated by translation attenuation and transcription attenuation mechanisms. Antibiotic-induced ribosome stalling during translation of an upstream open reading frame in the vmlR leader region prevents formation of an anti-antiterminator structure, leading to the formation of an antiterminator structure that prevents intrinsic termination. Thus, transcription in the presence of antibiotic induces vmlR expression. We also show that NusG-dependent RNA polymerase pausing in the vmlR leader prevents leaky expression in the absence of antibiotic. Furthermore, we demonstrate that induction of VmlR expression by compromised protein synthesis does not require the ability of VmlR to rescue the translational defect, as exemplified by constitutive induction of VmlR by ribosome assembly defects. Rather, the specificity of induction is determined by the antibiotic's ability to stall the ribosome on the regulatory open reading frame located within the vmlR leader. Finally, we demonstrate the involvement of (p)ppGpp-mediated signalling in antibiotic-induced VmlR expression.

The Effects of Agrimonia pilosa Ledeb, Anemone chinensis Bunge, and Smilax glabra Roxb on Broiler Performance, Nutrient Digestibility, and Gastrointestinal Tract Microorganisms.

Simple SummaryThere is a global effort to reduce the use of antibiotics in broiler production, and the antibacterial activity of extracts from Agrimonia pilosa Ledeb, Anemone chinensis Bunge, and Smilax glabra Roxb has been previously identified in vitro. The present study determines the effects of the dietary inclusion of these extracts on broiler production performance, nutrient digestibility, and on the levels of Campylobacter spp. and Escherichia coli, and lactic acid bacteria in the caecum. The inclusion of S. glabra Roxb and A. chinensis Bunge in broiler feed increased the number of lactic acid bacteria in the caeca of broilers, in comparison to the inclusion of antibiotics in poultry feed. The inclusion of S. glabra Roxb also reduced the levels of E. coli and Campylobacter spp., and improved the feed efficiency and weight gain. The plant extract of A. chinensis Bunge also increased weight gain in broilers. This study highlights the benefits of using S. glabra Roxb and A. chinensis Bunge in broiler feed as alternatives to antibiotics.Poultry farming is growing globally, particularly in developing countries, to meet the demands of growing populations for poultry meat and eggs. This is likely to lead to an increase in the use of antibiotics in poultry feed, thus contributing to the development and spread of antibiotic resistance which, poses a serious threat to human and animal health worldwide. One way of reducing this threat is to reduce the use of antibiotics in poultry production by finding effective and sustainable antibiotic alternatives that can be used to support poultry health and productivity. Therefore, this study evaluates the incorporation of three medicinal plants, Anemone chinensis Bunge, Smilax glabra Roxb, and Agrimonia pilosa Ledeb, in poultry feed on production performance, nutrient digestibility, and bacteria in the chicken caecum in a 35-day performance trial with 420-day-old male Ross 308 broilers. Groups of randomly selected chicks received one of six dietary treatments. These included five experimental diets of reduced nutrient specifications as a negative control (NC); with amoxicillin as a positive antibiotic control (PC1); with A. pilosa Ledeb (NC1); with A. chinensis Bunge (NC2); and with S. glabra Roxb (NC3). One other positive control diet contained the recommended nutrient specification (PC2). Weight gain and feed intake were measured weekly and used to calculate the feed conversion ratio as performance parameters. Bacteria were enumerated from chicken caecum using a traditional plating method and selective agar. S. glabra Roxb and A. chinensis Bunge showed comparable effects to amoxicillin with significantly increased weight gain in birds offered these diets, compared to those offered the negative control from days 0 to 35 (p < 0.001). S. glabra Roxb exhibited effects similar to the amoxicillin control group with an improved feed conversion ratio (p < 0.001). In addition, S. glabra Roxb decreased numbers of E. coli and Campylobacter spp. on days 21 (p < 0.05) and 35 (p < 0.01) and increased numbers of lactic acid bacteria comparable to the antibiotic group on days 14 (p < 0.001) and 35 (p < 0.01). The findings of this in vivo trial highlight the potential of S. glabra Roxb and A. chinensis Bunge as beneficial feed material to promote poultry health and productivity in the absence of antibiotics.

Performance, carcass characteristics, and health parameters of growing and finishing pigs fed with diets supplemented with isoquinoline alkaloids and essential oils

The goal of this study was to evaluate, in a commercial herd, the use of isoquinoline alkaloids and carvacrol versus a preventive antibiotic program, such as feed additives, on the performance, carcass traits, and health status of pigs in the growing and finishing phase. There were 576 PIC immunocastrated males and females, at 70 days of age and 28.429 ± 2.302 kg of initial weight used. The experimental design was a 4 × 2 factorial randomized block, with four preventive programs, two sexes, and six repetitions per treatment (the pen with 12 animals of the same sex was the replicate). The treatments were T1 (positive control program with antibiotic shocks at preventive level), T2 (negative control with the absence of antibiotics as a growth promoter or as preventive), T3 (isoquinoline alkaloids at 100 to 150 g ton-1), T4 (isoquinoline alkaloids at 90 g ton-1 + carvacrol essential oil at 1 kg ton-1). T1 and T3 presented higher daily feed intakes, followed by T2, and T4 showed the worst feed consumption (P &lt; 0.05). T1 showed higher daily weight gain compared to T4 (P &lt; 0.05), without differences between T2 and T3. T2 showed better feed conversion than T1 and T3, but it was similar to T4. There were no effects of the treatments on the carcass traits. Intestinal crypt hyperplasia and crypt abscesses (lesions caused by Lawsonia intracellularis) were significantly higher for T2 and T3 compared to T1, which was similar to T4. T2 presented the highest carcass condemnation at slaughter (7%), differing (P &lt; 0.05) from T1, T3, and T4 (1, 2, and 3%, respectively). Isoquinoline alkaloids are an alternative for antibiotic-free diets for pigs in the growing and finishing phase, preserving the performance and carcass indices and minimizing sanitary carcass condemnations at the slaughterhouse.

Endoscopic retrograde cholangiopancreatography for bile duct stones in patients with a performance status score of 3 or 4.

BACKGROUNDAs the aging population grows worldwide, the rates of endoscopic retrograde cholangiopancreatography (ERCP) for common bile duct stones (CBDS) in older patients with a poor performance status (PS) have been increasing. However, the data on the safety and efficacy of ERCP for CBDS in patients with a PS score of 3 or 4 are lacking, with only a few studies having investigated this issue among patients with poor PS.AIMTo examine the safety and efficacy of ERCP for CBDS in patients with a PS score of 3 or 4.METHODSThis study utilized a retrospective multi-centered design of three institutions in Japan for 8 years to identify a total of 1343 patients with CBDS having native papillae who underwent therapeutic ERCP. As a result, 1113 patients with a PS 0-2 and 230 patients with a PS 3-4 were included. One-to-one propensity-score matching was performed to compare the safety and efficacy of ERCP for CBDS between patients with a PS 0-2 and those with a PS 3-4.RESULTSThe overall ERCP-related complication rates in all patients and propensity score-matched patients with a PS 0-2 and 3-4 were 9.0% (100/1113) and 7.0% (16/230; P = 0.37), and 4.6% (9/196) and 6.6% (13/196; P = 0.51), respectively. In the propensity score-matched patients, complications were significantly more severe in the group with a PS 3-4 than in the group with a PS 0-2 group (P = 0.042). Risk factors for complications were indications of ERCP and absence of antibiotics in the multivariate analysis. Therapeutic success rates, including complete CBDS removal and permanent biliary stent placement, in propensity score-matched patients with a PS 0-2 and 3-4 were 97.4% (191/196) and 97.4% (191/196), respectively (P = 1.0).CONCLUSIONERCP for CBDS can be effectively performed in patients with a PS 3 or 4. Nevertheless, the indication for ERCP in such patients should be carefully considered with prophylactic antibiotics.

Untargeted lipidomic differences between clinical strains of methicillin-sensitive and methicillin-resistant Staphylococcus aureus

Background Staphylococcus aureus is a common cause of infectious diseases in humans. It has become resistant to many antibacterial agents making management of infections difficult. A better understanding of differences among S. aureus strains that are sensitive and resistant to antibiotics may offer insights into the resistant phenotype and identify new antimicrobial targets. This study aimed at comparing general differences in lipid profiles among clinical strains of S. aureus sensitive and resistant to antibiotics. The cell wall thickness and cell surface charge were also compared. Methods Five methicillin sensitive (MSSA) and five methicillin resistant (MRSA) S. aureus strains were compared both individually and as MSSA and MRSA groups in the absence of antibiotics. Lipids were compared by ultra-performance liquid chromatography-mass spectrometry, cell wall thickness was compared by scanning transmission electron microscopy and whole-cell surface charge was compared using a cytochrome c binding assay. Results Twenty-two lipid species were identified in all ten strains of S. aureus. The abundance of three lipid species (two lysyl-phosphatidylglycerol and one diglycosyldiacylglycerol) were found to be different between MSSA and MRSA. Differences in cell wall thickness were identified between strains but not between MSSA and MRSA. No difference in whole-cell surface charge was observed between MSSA and MRSA. Conclusion This study shows differences in membrane lipids between antibiotic sensitive and antibiotic resistant clinical strains of S aureus that may affect resistance mechanisms related to cell membrane structure and fluidity. Further research on these differences may identify new drug targets against resistant strains.

Hold the Antibiotics: Are Preoperative Antibiotics Unnecessary in the Treatment of Pediatric Supracondylar Humerus Fractures?

Supracondylar humerus (SCH) fracture is the most common elbow injury in children and often treated with closed reduction and percutaneous pinning (CRPP). There is little published evidence supporting or refuting the use of perioperative prophylactic antibiotics for SCH CRPP in the pediatric population. The purpose of this study is to evaluate the rate of surgical site infection for patients with and without preoperative antibiotics. A retrospective chart review was conducted of patients less than or equal to 16 years from 2012 to 2018 who underwent primary CRPP. Open fractures, multilimbed polytraumas, and immunodeficient patients were excluded. Infection rates were compared using a noninferiority test assuming a 3% infection rate and a predefined noninferiority margin of 4%. A total of 255 patients were needed to adequately power the study. Of the 1253 cases identified, 845 met eligibility criteria. A total of 337 received antibiotics, and 508 did not. Preoperative nerve injury (P=0.0244) and sterilization technique (P<0.0001) were associated with antibiotic use: 4 patients developed an infection; there were successfully treated superficial infections, and 1 was a deep infection requiring a formal debridement. There were 8 patients that had a recorded mal-union, and 6 patients required additional procedures; 1 patient had a postoperative compartment syndrome on postoperation day 1. The infection rates among patients treated with and without antibiotics were 0.60% and 0.40%, respectively. The absence of antibiotics was not clinically inferior to using antibiotics (P=0.003). Infection remains a rare complication following CRPP of SCH fractures. According to our current data, not giving perioperative antibiotics was not inferior to using perioperative antibiotics for preventing superficial or deep infection in patients undergoing CRPP of SCH fractures. With the increase in attention to antibiotic stewardship, it is important to eliminate unnecessary antibiotic use while continuing to maintain a low rate of surgical site infection. Level IV-case series. This is a therapeutic study that investigates the results from a case series.

Proteomic Signatures of Antimicrobial Resistance in Yersinia pestis and Francisella tularensis.

Antimicrobial resistance (AMR) is a well-recognized, widespread, and growing issue of concern. With increasing incidence of AMR, the ability to respond quickly to infection with or exposure to an AMR pathogen is critical. Approaches that could accurately and more quickly identify whether a pathogen is AMR also are needed to more rapidly respond to existing and emerging biological threats. We examined proteins associated with paired AMR and antimicrobial susceptible (AMS) strains of Yersinia pestis and Francisella tularensis, causative agents of the diseases plague and tularemia, respectively, to identify whether potential existed to use proteins as signatures of AMR. We found that protein expression was significantly impacted by AMR status. Antimicrobial resistance-conferring proteins were expressed even in the absence of antibiotics in growth media, and the abundance of 10–20% of cellular proteins beyond those that directly confer AMR also were significantly changed in both Y. pestis and F. tularensis. Most strikingly, the abundance of proteins involved in specific metabolic pathways and biological functions was altered in all AMR strains examined, independent of species, resistance mechanism, and affected cellular antimicrobial target. We have identified features that distinguish between AMR and AMS strains, including a subset of features shared across species with different resistance mechanisms, which suggest shared biological signatures of resistance. These features could form the basis of novel approaches to identify AMR phenotypes in unknown strains.

Antibiotic resistance genes in gut of breast-fed neonates born by caesarean section originate from breast milk and hospital ward air

The human gut is a reservoir of antibiotic resistance genes (ARGs). Even in the absence of antibiotics, ARGs are present in large quantities in faeces of adults, children and even newborns. However, where and when ARGs are acquired remains unclear, as does the types of ARGs acquired. Herein, we recruited 82 pairs of women and their caesarean section newborns. Conventional culture methods and quantitative PCR were employed to detect nine species and six ARG types in meconia, faeces from 3-day-old newborns, amniotic fluid, colostrum, and hospital ward air samples. Furthermore, ARG transfer was explored by tracking Staphylococcus epidermidis isolated from faeces of 3-day-old newborns, colostrum and ward air samples using multi-locus sequence typing (MLST). No ARGs or microorganisms were detected in meconia or amniotic fluid. One or more ARGs were detected in 90.2% of faeces from 3-day-old newborns, and the mecA gene exhibited the highest detection rate (45.1%). ARGs were detected in 85.4% of colostra consistent with ARGs in faeces from 3-day-old newborns. Some ARGs were detected in ward air, and might also be a source of ARGs in neonatal faeces. Isolation of S. epidermidis from neonatal faeces was consistent with antibiotic resistance and gene profiles for colostrum samples. Traceability analysis of S. epidermidis showed that ARGs in neonatal faeces mainly originated from colostrum, and partly from ward air. After birth, neonates born by caesarean section obtain a variety of ARGs mainly from colostrum, and partly from ward air.

Impact of antibiotic withdrawal and starvation conditions on plasmid elimination and consequent loss of resistance.

To assess resistance-loss due to plasmid elimination under experimental conditions, including withdrawal of antibiotics and administration of starvation conditions. The experimental study was conducted at the Department of Pathology, King Edward Medical University, Lahore, Pakistan, from July to December 2019. A single sensitive clinical isolate of escherichia coli, showing resistance towards ampicillin was collected and separately sub-cultured in three different culture broths: tryptic soya broth, minimal broth and control broth for a period of one month under standard laboratory conditions. Minimum inhibitory concentrations of the strains were calculated after every seven days to check antibiotic susceptibility. Minimum inhibitory concentrations of the initial escherichia coli strain measured on Day 1 was 6mg/mL and it became sensitive after continual sub-culturing in the absence of antibiotics in 21 days. Due to starvation conditions, the bacterial strain exhibited sensitivity to an even lower antibiotic concentration of 1.5mg/mL on the 28th day. Bacterial growth inhibition zones determined by disc diffusion method using an ampicillin disc of 10µg/mL showed no zone of inhibition. Provision of starvation conditions and withdrawal of antibiotic allowed the escherichia coli strain to exhibit gradual loss of resistance over a period of time.

Bacteroidales species in the human gut are a reservoir of antibiotic resistance genes regulated by invertible promoters

Antibiotic-resistance genes (ARGs) regulated by invertible promoters can mitigate the fitness cost of maintaining ARGs in the absence of antibiotics and could potentially prolong the persistence of ARGs in bacterial populations. However, the origin, prevalence, and distribution of these ARGs regulated by invertible promoters remains poorly understood. Here, we sought to assess the threat posed by ARGs regulated by invertible promoters by systematically searching for ARGs regulated by invertible promoters in the human gut microbiome and examining their origin, prevalence, and distribution. Through metagenomic assembly of 2227 human gut metagenomes and genomic analysis of the Unified Human Gastrointestinal Genome (UHGG) collection, we identified ARGs regulated by invertible promoters and categorized them into three classes based on the invertase-regulating phase variation. In the human gut microbiome, ARGs regulated by invertible promoters are exclusively found in Bacteroidales species. Through genomic analysis, we observed that ARGs regulated by invertible promoters have convergently originated from ARG insertions into glycan-synthesis loci that were regulated by invertible promoters at least three times. Moreover, all three classes of invertible promoters regulating ARGs are located within integrative conjugative elements (ICEs). Therefore, horizontal transfer via ICEs could explain the wide taxonomic distribution of ARGs regulated by invertible promoters. Overall, these findings reveal that glycan-synthesis loci regulated by invertible promoters in Bacteroidales species are an important hotspot for the emergence of clinically-relevant ARGs regulated by invertible promoters.

Organska hrana - pro et contra

Based on all available information, there has been a great expansion of organic food production and sale, both globally and in Serbia. It is estimated that this expansion results from buyers' belief that organic food is tastier and/or healthier, more nutritious, that it contains less pesticides, preservatives, additives, thaat it does not contain any genetically modified components, etc. However, which of these beliefs are facts, and which are misconceptions? In the absence of studies dealing with the issue of organic food in Serbia, we rely on the results of studies conducted in the world, primarily in countries where the production and sale of organic food has a decades-long tradition. Most studies covered by this review refer to the presence of pesticides in organic food and they all unequivocally established that organic food contains significantly lower amounts of pesticides than conventionally produced food. In terms of other aspects of health safety, it was found that organic food has significantly lower values or absence of antibiotics, growth hormones and factors, genetically modified components as well as artificial preservatives and additives. Some of the research that was conducted to confirm the claim that organic food is more nutritious than conventionally produced food, established that some foods have more vitamins, minerals and antioxidants. However, numerous studies did not confirm these conclusions, but rather found that there is no significant difference between the content of the mentioned ingredients in organic and conventional food. Which of the above is true will be confirmed by some future, fully objective studies.

Yapay et üretimi ve gelecek vizyonu

Artificial meat shows great promise as a method for use in future food production. It is predicted that traditional meat will be insufficient with the increasing human population. In addition, artificial meat has many advantages in terms of human health, such as being sustainable for the environment, controlled fat content, and absence of antibiotics and hormones compared to traditional meat. Artificial meat, also known as cultured meat, is produced through in vitro myogenesis, which includes muscle tissue-based protein products, stem cell culture, and differentiation, and mature muscle cell processing for flavor and texture. Artificial meat production consists of a sequential process; firstly muscle sampling for stem cell collection and followed by muscle tissue dissociation and muscle stem cell isolation, primary cell culture, high cell culture, and ending with muscle differentiation and maturation. A deep understanding of the process by considering its pros and cons will help not only artificial meat production but also the food industry in business sectors seeking new biomaterials. By explaining the methods utilized for artificial meat production, this study is created to prepare for the new era of cellular agriculture as well as for application in academia and industry.

Production of d-Tagatose by Whole-Cell Conversion of Recombinant Bacillus subtilis in the Absence of Antibiotics.

Simple Summaryd-tagatose is a valuable monosaccharide in the food industry produced from lactose by β-galactosidase and arabinose isomerase. To improve its production safety, d-alanine-deficient heterologous gene expression systems were constructed without antibiotics. The integrated expression and co-expression plasmids were used in different systems, also exploiting the need for d-alanine during cellular metabolism. The integration of the β-galactosidase gene in recombinant is uniquely innovative and promising, applying common knockout techniques to the expression of target genes and the production of high-value products.d-tagatose is a popular functional monosaccharide produced from lactose by β-galactosidase and arabinose isomerase. In this study, two d-alanine-deficient heterologous gene expression systems were constructed, B. subtilis 168 D1 and B. subtilis 168 D2, using overlapping extension PCR and the CRE/loxP system. The lacZ gene for β-galactosidase was integrated into a specific locus of the chassis B. subtilis 168 D2. A mutually complementary plasmid pMA5 with the alanine racemase gene alrA attached to it was constructed and used to assemble recombinant plasmids overexpressing β-galactosidase and arabinose isomerase. Afterward, an integrated recombinant was constructed by the plasmid expressing the arabinose isomerase gene araA of E. coli transform-competent B. subtilis 168 D2 cells. The co-expressing plasmids were introduced into alanine racemase knockout B. subtilis 168 D1. Whole-cell bioconversion was performed using the integrated recombinant with a maximum yield of 96.8 g/L d-tagatose from 500 g/L lactose, and the highest molar conversions were 57.2%. B. subtilis 168 D1/pMA5-alrA-araA-lacZ is capable of single-cell one-step production of d-tagatose. This study provides a new approach to the production of functional sugars.

Mycobacterium abscessus Genetic Determinants Associated with the Intrinsic Resistance to Antibiotics.

Mycobacterium abscessus subsp. abscessus (MAB) is a fast-growing nontuberculous mycobacterium causing pulmonary infections in immunocompromised and immunocompetent individuals. The treatment of MAB infections in clinics is extremely challenging, as this organism is naturally resistant to most available antibiotics. There is limited knowledge on the mechanisms of MAB intrinsic resistance and on the genes that are involved in the tolerance to antimicrobials. To identify the MAB genetic factors, including the components of the cell surface transport systems related to the efflux pumps, major known elements contributing to antibiotic resistance, we screened the MAB transposon library of 2000 gene knockout mutants. The library was exposed at either minimal inhibitory (MIC) or bactericidal concentrations (BC) of amikacin, clarithromycin, or cefoxitin, and MAB susceptibility was determined through the optical density. The 98 susceptible and 36 resistant mutants that exhibited sensitivity below the MIC and resistance to BC, respectively, to all three drugs were sequenced, and 16 mutants were found to belong to surface transport systems, such as the efflux pumps, porins, and carrier membrane enzymes associated with different types of molecule transport. To establish the relevance of the identified transport systems to antibiotic tolerance, the gene expression levels of the export related genes were evaluated in nine MAB clinical isolates in the presence or absence of antibiotics. The selected mutants were also evaluated for their ability to form biofilms and for their intracellular survival in human macrophages. In this study, we identified numerous MAB genes that play an important role in the intrinsic mechanisms to antimicrobials and further demonstrated that, by targeting components of the drug efflux system, we can significantly increase the efficacy of the current antibiotics.