The number of studies of controlled drug-release systems is growing constantly. Bionanocomposite materials which can be prepared from the combination of biopolymers with inorganic solids such as clay minerals offer interesting alternatives for use as drug-delivery systems. In the present study, new bionanocomposite drug-release systems were prepared from the intercalation of the antibiotic drug ciprofloxacin into montmorillonite using an ion-exchange reaction. In order to prepare more stable systems for oral ciprofloxacin release, this ciprofloxacin-clay intercalation compound was incorporated into i-carrageenan-gelatin biopolymer blend to produce bionanocomposite materials. Bionanocomposites of two distinct i-carrageenan and gelatin mass ratios were conformed as beads through an ionic gelification reaction with Ca2+ ions, and dried by freeze-drying where liquid nitrogen or conventional freezing was adopted in the freezing step. The resulting ciprofloxacin-clay hybrid was characterized by X-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, solid state 13C Nuclear Magnetic Resonance (NMR), thermal analysis, and scanning electron microscopy (SEM). The montmorillonite-ciprofloxacin hybrid incorporated into the bionanocomposite beads was evaluated by in vitro release studies which showed a significant difference in the release profiles in the aqueous medium used to simulate the gastrointestinal tract, depending on the blend composition and the freezing method employed in the preparation of the beads. The results point to bionanocomposite systems based on ciprofloxacin-clay hybrids and biopolymers that may be used as devices in the biomedical area.

Antagonism among bacteria is widespread and plays an important role in structuring communities. Inhibitory compounds can confer competitive advantage, but energetic trade-offs can result in non-transitive (i.e. ‘rock-paper-scissors’) interactions, ultimately allowing co-existence and community stability. Competition in sedimentary habitats is especially keen given high densities and attachment to inorganic particles. Because measuring trade-offs between bacterial species is challenging, much of our understanding of competitive interactions is based on theoretical modelling and simplified in vitro experiments. Our objectives were to determine (1) if interference competition occurs in microcosms mimicking in situ conditions; (2) whether the presence of sediment influences antagonistic interactions; and (3) if more complex assemblages alleviate or synergize interactions. Four sedimentary isolates, including antibiotic-producing, resistant and susceptible strains were incubated in porewater microcosms in 1-, 2- and 3-species combinations, both with and without natural sediments. Microcosms were sampled over 72 h to generate growth curves using quantitative PCR. Multiple growth attributes (growth rate, maximum density, lag time) were used to assess effects of treatment (species combinations) and environment (sediment vs porewater alone). Antimicrobial producers were more effective at inhibiting target species in microcosms that included sediment, in agreement with theory. We observed growth inhibition by antimicrobial-producing bacteria in both 2- and 3-species microcosms. However, the expected protection of sensitive bacterial strains by resistant strains was observed in only one (of four) 3-species combinations, thus the ‘rock-paper-scissors’ prediction was not fully supported. These results reinforce the notion that interspecies interactions are context-dependent, reliant on environmental conditions and the species involved.

Infusion of an internal teat sealant into the mammary gland of the dairy cow at drying off has been claimed to reduce the incidence of clinical mastitis over many months in the subsequent lactation, despite the absence of any ingredient of the sealant remaining for that long. However, these claims have been poorly substantiated, often by lack of identification on when the infection occurred in the period from calving to disease, if the infection was present at post calving sampling and if the pathogen causing the disease was that causing an earlier infection. Moreover, no hypothesis on how any effect on clinical mastitis might occur has been advanced in any of the publications claiming the effect. That the effect might occur is only reported in a minority of publications, and the possibility that this is relatively specific to Gram-negative pathogens is reviewed.

Antibiotics are designed to affect gut microbiota and subsequently gut homeostasis. However, limited information exists about short- and long-term effects of early antibiotic intervention (EAI) on gut homeostasis (especially for the small intestine) of pigs following antibiotic withdrawal. We investigated the impact of EAI on specific bacterial communities, microbial metabolites and mucosal immune parameters in the small intestine of later-growth-stage pigs fed with diets differing in CP levels. Eighteen litters of piglets were fed creep feed with or without antibiotics from day 7 to day 42. At day 42, pigs within each group were offered a normal- or low-CP diet. Five pigs per group were slaughtered at days 77 and 120. At day 77, EAI increased Enterobacteriaceae counts in the jejunum and ileum and decreased Bifidobacterium counts in the jejunum and ileum (P < 0.05). Moreover, tryptamine, putrescine, secretory immunoglobulin (Ig) A and IgG concentrations in the ileum and interleukin-10 (IL-10) mRNA and protein levels in the jejunum and ileum were decreased in pigs with EAI (P < 0.05). At day 120, EAI only suppressed Clostridium cluster XIVa counts in the jejunum and ileum (P < 0.05). These results suggest that EAI has a short-term effect on specific bacterial communities, amino acid decarboxylation and mucosal immune parameters in the small intestine (particularly in the ileum). At days 77 and 120, feeding a low-CP diet affected Bifidobacterium, Clostridium cluster IV, Clostridium cluster XIVa and Enterobacteriaceae counts in the jejunum or ileum (P < 0.05). Moreover, feeding a low-CP diet increased the concentrations of Igs in the jejunum and decreased pro-inflammatory cytokines levels in the jejunum and ileum (P < 0.05). At day 120, feeding a low-CP diet increased short-chain fatty acid concentrations, reduced ammonia and spermidine concentrations and up-regulated genes related to barrier function in the jejunum and ileum (P < 0.05). These results suggest that feeding a low-CP diet changes specific bacterial communities and intestinal metabolite concentrations and modifies mucosal immune parameters. These findings contribute to our understanding on the duration of the impact of EAI on gut homeostasis and may provide basis data for nutritional modification in young pigs after antibiotic treatment.

Use of antimicrobials for food-producing animals is a major public concern due to the risk of antimicrobial resistance. Although dairy production has a relatively low usage of antimicrobials, the potential for further reduction should be explored. The objective of the study was to estimate the current differences in antimicrobial use in Danish organic and conventional dairy herds and to describe the differences between them. Based on data from three different sources, 2604 herds (306 organic and 2298 conventional) were identified for the study. These herds had been either organic or conventional for the entire period from 2015 to 2018. Antimicrobial use was calculated as the treatment incidence in Animal Daily Doses (ADDs)/100 animals/day for three age groups: adult cattle, young stock and calves. For adult cattle, the ratio of median treatment incidence between conventional and organic production ranged from 2.8 : 1 to 3.4 : 1, depending on the specific year. For cows, 25% of the organic herds had a higher treatment incidence than the 25% of conventional herds with the lowest treatment incidence. Antimicrobial use for young stock was low and at a similar level in both the organic and conventional production systems. For calves, the median treatment incidence was 1.2 times higher in conventional herds and 1.6 times higher for the 75th percentile. Analyses of treatment incidence in adult cattle showed an overall decrease from 2015 to 2018 in both organic and conventional herds. The decrease was greater for the conventional herds (0.12 ADD/100 animals/day) compared to the organic herds (0.04 ADD/100 animals/day) over the 4-year period. In addition, herd size was an important risk factor for treatment incidence in conventional herds, increasing by 0.07 ADD/100 animals/day per 100 cows, whereas herd size had a minor influence on the treatment incidence in organic herds. The results of this study demonstrate the large variation in antimicrobial use within both organic and conventional herds, suggesting that further reduction is possible. Furthermore, herd size appears to be a risk factor in conventional herds but not in organic herds – an aspect that should be studied in more detail.

Introduction: Acute pharyngitis is a common emergency department (ED) presentation. The Centor (Modified/McIsaac) score uses five criteria (age, tonsillar exudates, swollen tender anterior cervical nodes, absence of a cough, and history of fever) to predict Group A Streptococcus (GAS) infection. The recommendation is patients with a Centor score of 0-1 should not undergo testing and should not be given antibiotics, patients with a score of 2-3 may warrant throat cultures, and for patients with a score ≥ 4, empiric antibiotics may be appropriate. Associated pain is often first managed with acetaminophen or non-steroidal anti-inflammatory drugs, however recent evidence suggests a short course of low-to-moderate dose corticosteroids as adjunctive therapy may reduce inflammation and provide pain relief. The objective of this study was to describe the ED management of acute pharyngitis for adult patients presenting to an academic ED over a two-year study period. Methods: This was a retrospective chart review of all adult (> 17 years) patients presenting to Mount Sinai Hospital ED with a discharge diagnosis of acute pharyngitis (ICD-10 code J02.9) from January 1st 2016 to December 31st 2018. Trained research personnel reviewed medical records and extracted data using a computerized, data abstraction form. Results: Of the 638 patients included in the study, 286 (44.8%) had a Centor score of 0-1, 328 (51.4%) had a score of 2-3, and 24 (3.8%) had a score of ≥ 4. Of those with a Centor score of 0-1, 83 (29.0%) had a throat culture, 88 (30.8%) were prescribed antibiotics, 15 (5.2%) were positive for GAS and 74 (25.9%) were given corticosteroids in the ED or at discharge. Of those with a Centor score of 2-3, 156 (47.6%) had a throat culture, 220 (67.1%) were prescribed antibiotics, 44 (13.4%) were positive for GAS, and 145 (44.2%) were given corticosteroids. Of those with a Centor score ≥ 4, 14 (58.3%) had a throat culture, 18 (75.0%) were prescribed antibiotics, 7 (29.2%) were positive for GAS and 12 (50.0%) were given corticosteroids. Conclusion: As predicted, a higher Centor score was associated with higher risk of GAS infection, increased antibiotic prescribing and use of corticosteroids. Many patients with low Centor scores were prescribed antibiotics and also had throat cultures. Further work is required to understand clinical decision making for the management of acute pharyngitis.