Tetracycline Resistance Patterns of Lactobacillus buchneri Group Strains

Safety and efficacy of a feed additive consisting of Lentilactobacillus diolivorans (formerly Lactobacillus diolivorans) DSM 33625 as a silage additive for all animal species (Lactosan GmbH & Co.KG)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on Lentilactobacillus diolivorans (formerly Lactobacillus diolivorans) DSM 33625 when used as a technological additive to improve ensiling of forage. The additive is intended for use with all forages and for all animal species at a proposed minimum concentration of 1 × 10⁸ colony forming units (CFU)/kg forage. The bacterial species L. diolivorans is considered by EFSA to be suitable for the qualified presumption of safety approach to safety assessment. As the identity of the strain has been clearly established and no acquired antimicrobial resistance determinants of concern were detected, the use of the strain as a silage additive is considered safe for livestock species, for consumers of products from animals fed the treated silage and for the environment. The additive is not a skin or an eye irritant. In the absence of data, no conclusion can be drawn on the skin sensitisation of the additive. Given the proteinaceous nature of the active agent, the additive should be considered a respiratory sensitiser. The FEEDAP Panel concluded that Lentilactobacillus diolivorans DSM 33625 at a minimum concentration of 1 × 10⁸ CFU/kg forage may extend the aerobic stability of silage prepared from easy and moderately difficult to ensile forage material with a DM range of 32-65%.

Assessment of eight feed additives consisting of Lactiplantibacillus plantarumCNCM I-3235, L. plantarumCNCM I-3736/DSM 11672, Pediococcus acidilacticiCNCM I-3237, P. acidilacticiCNCM I-4622/DSM 11673, Pediococcus pentosaceusNCIMB 12455, Acidipropionibacterium acidipropioniciCNCM I-4661, Lentilactobacillus buchneriNCIMB 40788/CNCM I-4323 and L. buchneriNCIMB 40788/CNCM I-4323 plus Lentilactobacillus hilgardiiCNCM I-4785 for all animal species for the renewal of their authorisation (Danstar Ferment AG)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of eight technological additives, including two Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) [CNCM I-3235 and CNCM I-3736/ DSM 11672], two Pediococcus acidilactici [CNCM I-3237 and CNCM I-4622/DSM 11673], one Pediococcus pentosaceus [NCIMB 12455], one Acidipropionibacterium acidipropionici (formerly Propionibacterium acidipropionici) [CNCM I-4661], one Lentilactobacillus buchneri (formerly Lactobacillus buchneri) [NCIMB 40788/ CNCM I-4323], and the additive composed by the two active agents L. buchneri NCIMB 40788/ CNCM I-4323 and Lentilactobacillus hilgardii (formerly Lactobacillus hilgardii) CNCM I-4785, as silage additives for use in forage for all animal species. The applicant has provided evidence that the additives currently on the market comply with the existing conditions of authorisation. There is no new evidence that would lead the FEEDAP Panel to reconsider its previous conclusions. Thus, the Panel concluded that the additives remain safe for all animal species, consumers and the environment under the authorised conditions of use. Regarding user safety, the additives should be considered as respiratory sensitisers. In the absence of data, no conclusions could be drawn on the skin sensitisation, and skin and eye irritancy potential of the additives, with the exception for Pediococcus acidilactici CNCM I-4622/DSM 11673 (for which the Panel concluded that is non-irritant to skin and eyes). There is no need for assessing the efficacy of the additives in the context of the renewal of the authorisation.

Potentiality of Food-Isolated Lentilactobacillus kefiri Strains as Probiotics: State-of-Art and Perspectives

Lentilactobacillus kefiri is one of the main lactic acid bacteria species in kefir and it was also isolated from other fermented foods. Numerous strains have been isolated and characterized regarding its potential as probiotics for the development of novel functional foods. To our knowledge this is the first review focused on highlighting safety aspects and health beneficial effects reported for L. kefiri strains. Several L. kefiri strains lack of transmissible antibiotic resistance genes, are tolerant to the harsh conditions of the gastrointestinal environment, and could resist different preservation procedures. Moreover, many of the isolated strains have shown antimicrobial activity against pathogens and their toxins, exhibited immunomodulatory activity as well as induced some beneficial effects at metabolic level. Regarding all the scientific evidence, certain L. kefiri strains emerge as excellent candidates to be applied to the development of both food supplements and new fermented foods with health-promoting properties. However, the availability of genomic information is still very limited, so much more work must be done in order to explore the potentiality of L. kefiri as a probiotic and a source of bioactive metabolites.

Impact of Chronic Tetracycline Exposure on Human Intestinal Microbiota in a Continuous Flow Bioreactor Model

Studying potential dietary exposure to antimicrobial drug residues via meat and dairy products is essential to ensure human health and consumer safety. When studying how antimicrobial residues in food impact the development of antimicrobial drug resistance and disrupt normal bacteria community structure in the intestine, there are diverse methodological challenges to overcome. In this study, traditional cultures and molecular analysis techniques were used to determine the effects of tetracycline at chronic subinhibitory exposure levels on human intestinal microbiota using an in vitro continuous flow bioreactor. Six bioreactor culture vessels containing human fecal suspensions were maintained at 37 °C for 7 days. After a steady state was achieved, the suspensions were dosed with 0, 0.015, 0.15, 1.5, 15, or 150 µg/mL tetracycline, respectively. Exposure to 150 µg/mL tetracycline resulted in a decrease of total anaerobic bacteria from 1.9 × 10⁷ ± 0.3 × 10⁷ down to 2 × 10⁶ ± 0.8 × 10⁶ CFU/mL. Dose-dependent effects of tetracycline were noted for perturbations of tetB and tetD gene expression and changes in acetate and propionate concentrations. Although no-observed-adverse-effect concentrations differed, depending on the traditional cultures and the molecular analysis techniques used, this in vitro continuous flow bioreactor study contributes to the knowledge base regarding the impact of chronic exposure of tetracycline on human intestinal microbiota.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 11: suitability of taxonomic units notified to EFSA until September 2019

Qualified presumption of safety (QPS) was developed to provide a generic safety evaluation for biological agents to support EFSA's Scientific Panels. The taxonomic identity, body of knowledge, safety concerns and antimicrobial resistance are assessed. Safety concerns identified for a taxonomic unit (TU) are where possible to be confirmed at strain or product level, reflected by 'qualifications'. No new information was found that would change the previously recommended QPS TUs and their qualifications. The list of microorganisms notified to EFSA was updated with 54 biological agents, received between April and September 2019; 23 already had QPS status, 14 were excluded from the QPS exercise (7 filamentous fungi, 6 Escherichia coli, Sphingomonas paucimobilis which was already evaluated). Seventeen, corresponding to 16 TUs, were evaluated for possible QPS status, fourteen of these for the first time, and Protaminobacter rubrum, evaluated previously, was excluded because it is not a valid species. Eight TUs are recommended for QPS status. Lactobacillus parafarraginis and Zygosaccharomyces rouxii are recommended to be included in the QPS list. Parageobacillus thermoglucosidasius and Paenibacillus illinoisensis can be recommended for the QPS list with the qualification 'for production purposes only' and absence of toxigenic potential. Bacillus velezensis can be recommended for the QPS list with the qualification 'absence of toxigenic potential and the absence of aminoglycoside production ability'. Cupriavidus necator, Aurantiochytrium limacinum and Tetraselmis chuii can be recommended for the QPS list with the qualification 'production purposes only'. Pantoea ananatis is not recommended for the QPS list due to lack of body of knowledge in relation to its pathogenicity potential for plants. Corynebacterium stationis, Hamamotoa singularis, Rhodococcus aetherivorans and Rhodococcus ruber cannot be recommended for the QPS list due to lack of body of knowledge. Kodamaea ohmeri cannot be recommended for the QPS list due to safety concerns.

Development of Bacterial Therapeutics against the Bovine Respiratory Pathogen Mannheimia haemolytica

Bovine respiratory disease (BRD) is a major cause of morbidity and mortality in beef cattle. Recent evidence suggests that commensal bacteria of the bovine nasopharynx have an important role in maintaining respiratory health by providing colonization resistance against pathogens. The objective of this study was to screen and select bacterial therapeutic candidates from the nasopharynxes of feedlot cattle to mitigate the BRD pathogen Mannheimia haemolytica In a stepwise approach, bacteria (n = 300) isolated from the nasopharynxes of 100 healthy feedlot cattle were identified and initially screened (n = 178 isolates from 12 different genera) for growth inhibition of M. haemolytica Subsequently, selected isolates were evaluated for the ability to adhere to bovine turbinate (BT) cells (n = 47), compete against M. haemolytica for BT cell adherence (n = 15), and modulate gene expression in BT cells (n = 10). Lactobacillus strains had the strongest inhibition of M. haemolytica, with 88% of the isolates (n =33) having inhibition zones ranging from 17 to 23 mm. Adherence to BT cells ranged from 3.4 to 8.0 log10 CFU per 105 BT cells. All the isolates tested in competition assays reduced M. haemolytica adherence to BT cells (32% to 78%). Among 84 bovine genes evaluated, selected isolates upregulated expression of interleukin 8 (IL-8) and IL-6 (P < 0.05). After ranking isolates for greatest inhibition, adhesion, competition, and immunomodulation properties, 6 Lactobacillus strains from 4 different species were selected as the best candidates for further development as intranasal bacterial therapeutics to mitigate M. haemolytica infection in feedlot cattle.IMPORTANCE Bovine respiratory disease (BRD) is a significant animal health issue impacting the beef industry. Current BRD prevention strategies rely mainly on metaphylactic use of antimicrobials when cattle enter feedlots. However, a recent increase in BRD-associated bacterial pathogens that are resistant to metaphylactic antimicrobials highlights a pressing need for the development of novel mitigation strategies. Based upon previous research showing the importance of respiratory commensal bacteria in protecting against bronchopneumonia, this study aimed to develop bacterial therapeutics that could be used to mitigate the BRD pathogen Mannheimia haemolytica Bacteria isolated from the respiratory tracts of healthy cattle were characterized for their inhibitory, adhesive, and immunomodulatory properties. In total, 6 strains were identified as having the best properties for use as intranasal therapeutics to inhibit M. haemolytica If successful in vivo, these strains offer an alternative to metaphylactic antimicrobial use in feedlot cattle for mitigating BRD.

Transfer of a mobile Staphylococcus saprophyticus plasmid isolated from fermented seafood that confers tetracycline resistance

The complete nucleotide sequence of a tetracycline-resistance gene (tetK)-carrying plasmid from a Staphylococcus saprophyticus isolate from jeotgal, a Korean high-salt-fermented seafood, was determined. The plasmid, designated pSSTET1, was 4439 bp in length and encoded typical elements found in plasmids that replicate via a rolling-circle mechanism, including the replication protein gene (rep), a double-stranded origin of replication, a single-stranded origin of replication, and a counter-transcribed RNA sequence. Additionally, the plasmid recombination enzyme gene (pre), which may be involved in inter-plasmid recombination and conjugation, was found. Each gene exhibited >94% sequence identity with those harbored in other Staphylococcus species. pSSTET1 was conditionally transferred to Staphylococcus species in a host-dependent manner and transferred to an Enterococcus faecalis strain in vitro. Antibiotic susceptibility of the transconjugants was host-dependent and transconjugants maintained a tetracycline-resistant phenotype in the absence of selective pressure over 100 generations.

Safety and efficacy of Lactobacillus buchneri NRRL B-50733 as a silage additive for all animal species

Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP), was asked to deliver a scientific opinion on the safety and efficacy of a strain of Lactobacillus buchneri when used as a technological additive intended to improve ensiling at a proposed application rate of 1 × 10⁸ colony forming units (CFU)/kg fresh material. The bacterial species L. buchneri is considered by EFSA to be suitable for the qualified presumption of safety approach to safety assessment. As the identity of the strain has been clearly established and as no antibiotic resistance of concern was detected, the use of the strain as a silage additive is considered safe for livestock species, for consumers of products from animals fed the treated silage and for the environment. In the absence of data, no conclusion can be drawn on the skin and eye irritancy or skin sensitisation of the additive. The additive should be considered a potential respiratory sensitiser. Three studies with laboratory‐scale silos were made using samples of easy, moderately difficult and difficult to ensile material. In each case, replicate silos containing untreated forage were compared with identical silos containing the same forage treated with the combination of Lactobacillus buchneri NRRL B‐50733 at an intended concentration of 1 × 10⁸ CFU/kg fresh matter. The results showed that the addition of Lactobacillus buchneri NRRL B‐50733 at 1 × 10⁸ CFU/kg fresh material has the potential to improve the aerobic stability of silage with a dry matter content ranging from 30% to 73%.