Lactobacilli – bacteria–host interactions with special regard to the urogenital tract

Effect of sex on the gut microbiota characteristics of passerine migratory birds

The gut microbiota, considered the “invisible organ” in the host animal, has been extensively studied recently. However, knowledge about the gut microbiota characteristics of passerine migratory birds during migration is limited. This study investigated the gut microbiota characteristics of three dominant migratory bird species (namely orange-flanked bluetail Tarsiger cyanurus, yellow-throated bunting Emberiza elegans, and black-faced bunting Emberiza spodocephala) in the same niche during spring migration and whether they were bird sex-specific. The compositions of gut microbiota species in these three migratory bird species and their male and female individuals were found to be similar. The main bacterial phyla were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, and the main genera were Lactobacillus, Acinetobacter, Rickettsiella, and Mycobacterium; however, their relative abundance was different. Moreover, some potential pathogens and beneficial bacteria were found in all the three bird species. Alpha diversity analysis showed that in T. cyanurus, the richness and diversity of the gut microbiota were higher in male individuals than in female individuals, while the opposite was true for E. elegans and E. spodocephala. The alpha diversity analysis showed significant differences between male and female individuals of E. elegans (p < 0.05). The beta diversity analysis also revealed that the gut microbial community structure differed significantly between the male and female individuals of the three migratory bird species.

The biosurfactants iturin, lichenysin and surfactin, from vaginally isolated lactobacilli, prevent biofilm formation by pathogenic Candida

Lactic acid bacteria (LAB), particularly lactobacilli, are major components of the vaginal microbiota. Lactobacilli are facultative anaerobes forming a critical line of defense against pathogenic microorganisms, including those forming biofilms, such as Candida spp. This study aimed to investigate the anti-adhesion capabilities of vaginal Lactobacillus isolates against biofilms formed by pathogenic Candida species. When the extracellular biosurfactant activities of culture supernatants from 120 Lactobacillus isolates were evaluated by the oil-spreading method, clear spreading zones were recognized. Biofilm formation was quantified by the crystal violet plate assay, and different isolates exhibited anti-adhesion activity that ranged from 65.6to 74.4% inhibition against Candida spp. biofilms. Liquid chromatography high-resolution electrospray ionization mass spectrometry (LC-HRESIMS) identified biosurfactants, extracted from three representative Lactobacillus isolates, as surfactin, iturin and lichenysin. Finally, the distribution of representative genes from six different biosynthetic clusters, related to the production of different biosurfactants, was investigated by the polymerase chain reaction. In conclusion, surfactin, iturin and lichenysin were identified for the first time in vaginal Lactobacillus spp. These biosurfactants, which showed strong anti-adherence activity may be used as promising antibiofilm agents in equipment care to prevent vaginal infections by pathogenic Candida spp. with the prospect of reducing nosocomial infections.

Rational use of antibiotics for treatment of urinary infection in sows

Abstract The endemic character of urinary infections (UI) in sows makes collective antimicrobial therapies via feed a routine. This, however, generates sub-doses unable to heal and contribute to the selection of antibiotic-resistant bacteria. The use of individual therapy is the most appropriate procedure to be performed on animals with UI. With this study, we aimed to evaluate the occurrence of UI in sows housed in the western region of Paraná and the efficacy and cost-benefit of individual treatment. A total of 353 females were selected from five different herds, submitted to urine collection in the final third of pregnancy by spontaneous urination method. The samples were analyzed physically and chemically with the use of reagent strips, and the presence of nitrite was a determinant for positivity for UI. The animals with UI had urine submitted to a bacteriological evaluation, were treated with parenteral medication (marbofloxacin - single dose - 8 mg/kg), and submitted to a new urine collection 24h and 48h after the first. UI was observed in 4.53% of the females evaluated (16/353). Escherichia coli and Streptococcus sp. were the most frequently isolated agents. Seven days after the use of marbofloxacin 87.5% (14/16) of the animals were negative for UI, which demonstrates the efficacy of UI parenteral control. The diagnosis associated with individual therapy at the expense of collective medication was highly cost-effective, made it possible to drastically reduce the number of medicated animals, and was efficient in controlling UI. Thus, it is concluded that it is possible to make rational use of antibiotics by treating only sows that are proven to be positive for UI. This reduces the number of unnecessarily medicated animals and reduces the cost due to the use of antimicrobials only in sick animals.

Lactobacillus plantarum ameliorates tumour necrosis factor-induced bacterial translocation in Caco-2 cells by regulation of TLR4 expression

Purpose. Translocation of bacteria across the intestinal barrier is important in the pathogenesis of systemic sepsis. In inflammatory conditions, commensal bacteria exploit transcytotic pathways to cross the intestinal epithelium in a TLR4-dependent manner. The aim of this study was to test the hypothesis that Lactobacillus plantarum ameliorates tumour necrosis factor-induced bacterial translocation by regulation of Toll-like receptor-4 expression.Methodology. L. plantarum strains were investigated to determine their capacity to inhibit the initial adhesion of Escherichia coli B5 to Caco-2 cells. The inhibitory effects of L. plantarum on TNF-α-induced E. coli B5 translocation across Caco-2 cells were studied. Barrier function and integrity were simultaneously assessed by transepithelial electrical resistance, HRP permeability, LDH release and distribution of tight junctional proteins. Expression of TLR4 was assessed by RT-PCR.Results/Key findings. Pretreatment of monolayers with L. plantarum L2 led to a significant decrease in E. coli B5 adhesion and cell internalization (P<0.01). Exposure to TNF-α for six hours caused a significant increase in E. coli B5 translocation across Caco-2 cells, which was uncoupled from increases in paracellular permeability and disruption of tight junction proteins. Manipulations that induced bacterial translocation were associated with a marked increase in TLR4 mRNA expression and IL-8 secretion. L. plantarum L2 significantly abrogated TNF-α-induced bacterial translocation of E. coli B5, and also downregulated expression of TLR4 and IL-8 in intestinal epithelial cells.Conclusion. Live L. plantarum L2 can inhibit TNF-α-induced transcellular bacterial translocation via regulation of TLR4 expression.

Population and Culture Age Influence the Microbiome Profiles of House Dust Mites

Interactions with microorganisms might enable house dust mites (HDMs) to derive nutrients from difficult-to-digest structural proteins and to flourish in human houses. We tested this hypothesis by investigating the effects of changes in the mite culture growth and population of two HDM species on HDM microbiome composition and fitness. Growing cultures of laboratory and industrial allergen-producing populations of Dermatophagoides farinae (DFL and DFT, respectively) and Dermatophagoides pteronyssinus (DPL and DPT, respectively) were sampled at four time points. The symbiotic microorganisms of the mites were characterized by DNA barcode sequencing and quantified by qPCR using universal/specific primers. The population growth of mites and nutrient contents of mite bodies were measured and correlated with the changes in bacteria in the HDM microbiome. The results showed that both the population and culture age significantly influenced the microbiome profiles. Cardinium formed 93% and 32% of the total sequences of the DFL and DFT bacterial microbiomes, respectively, but this bacterial species was less abundant in the DPL and DPT microbiomes. Staphylococcus abundance was positively correlated with increased glycogen contents in the bodies of mites, and increased abundances of Aspergillus, Candida, and Kocuria were correlated with increased lipid contents in the bodies of mites. The xerophilic fungus Wallemia accounted for 39% of the fungal sequences in the DPL microbiome, but its abundance was low in the DPT, DFL, and DFT microbiomes. With respect to the mite culture age, we made three important observations: the mite population growth from young cultures was 5-8-fold higher than that from old cultures; specimens from old cultures had greater abundances of fungi and bacteria in their bodies; and yeasts predominated in the gut contents of specimens from young cultures, whereas filamentous mycelium prevailed in specimens from old cultures. Our results are consistent with the hypothesis that mites derive nutrients through associations with microorganisms.

Lactobacilli enhance reactive oxygen species-dependent apoptosis-inducing signaling

H₂O₂-producing lactobacilli in the vaginal fluid have been suggested to play a potential tumor-preventive role in addition to the control of undesirable microorganisms. As the vaginal fluid also contains a significant concentration of peroxidase that might utilize lactobacilli-derived H₂O₂ as substrate for HOCl synthesis, a dominant biological role of HOCl in both natural defence systems has been postulated.

Our study shows that lactobacillus-derived H₂O₂ per se is not likely to be beneficial for the vaginal epithelium, as it causes apoptosis nonselectively in nontransformed as well as transformed cells. However, the combination of lactobacilli and peroxidase, i.e. the situation that is actually found in vivo, leads to the conversion of H₂O₂ to HOCl which does not affect non-malignant cells, as these do not generate extracellular superoxide anions. In contrast, malignant cells, due to their abundant extracellular superoxide anion generation allow the generation of apoptosis-inducing hydroxyl radicals through HOCl/superoxide anion interaction. In total, our data show that the combination of H₂O₂ -generating lactobacilli and peroxidase causes the selective elimination of malignant cells and thus might contribute to the tumorpreventive potential of lactobacilli. These findings are in good agreement with epidemiological data. The contribution of lactobacilli in this system can be completely mimicked by H₂O₂-generating glucose oxidase, indicating that it is fully explained by bacterial generation of H₂O₂.

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Lactobacillus-derived H₂O₂ induces apoptosis in nontransformed and transformed cells.

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MPO converts H₂O₂ into HOCl that exerts a selective apoptosis-inducing effect on malignant cells.

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Extracellular superoxide anions of malignant cells are crucial for selective apoptosis induction.

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A model for the tumor protective role of lactobacilli in the presence of peroxidase is presented.

Technological and Probiotic Traits of the Lactobacilli Isolated From Vaginal Tract of the Healthy Women for Probiotic Use

Background

For biotechnological application, selected lactic acid bacteria strains belonging to the genera Lactobacillus (Lb) are proposed as an alternative to the antibiotics for the prevention and treatment of urogenital tract infections.

Objectives

Isolating and selecting vaginal lactobacilli strains for probiotic use based on their technological and probiotic aptitudes.

Materials and Methods

The vaginal isolates were examined for their essential characteristics as the potential probiotic such as low pH tolerance, bile-salt and simulated human intestinal fluid (SIF) resistance, adhesion to the vaginal epithelial cells (VECs), aggregation and coaggregation, surface hydrophobicity, antimicrobial activity, acid production, antibiotic resistance, and resistance to spermicides. The best strain was identified by PCR.

Results

From 70 lactobacilli isolates and according to the 16 rDNA sequences, isolates B6 and B10 showed the closest homology (99%) to the Lb. gasseri and Lb. plantarum respectively. They produced hydrogen peroxide (H₂O₂), tolerant to acid, bile, simulated human intestinal fluid, present a strong adhesion, highest percentages of aggregation, and antibacterial activity. These strains are resistant to the spermicide and actively acidify the growth medium.

Conclusions

Strains Lb. plantarum B10 and Lb. gasseri B6 have a strong potential probiotic confirming their value as a tool for prevention against urinary and vaginal infections.

Probiotic attributes of indigenous Lactobacillus spp. isolated from traditional fermented foods and beverages of north-western Himalayas using in vitro screening and principal component analysis

The present research was designed to explore indigenous probiotic Lactic acid bacteria from traditional fermented foods and beverages of North-western Himalayas for their probiotic potential. It was achieved through a step-by step approach focused on the technological characterization, evaluation of the probiotic traits and adherence ability. Fifty one LAB isolates from traditional fermented foods and beverages were initially screened for their technological properties and among them twenty isolates were selected. These isolates were further characterized and identified using 16S rRNA gene sequencing as Lactobacillus brevis (7 isolates), Lactobacillus casei (5), Lactobacillus paracasei (2), Lactobacillus buchneri (1), Lactobacillus plantarum (1) and Lactobacillus sp. (3). Identified isolates were evaluated by in vitro methods including survival in gastrointestinal tract, antibiotic susceptibility, antimicrobial activity, cell surface characteristics, exopolysacharride production and haemolytic activity. The results of these experiments were used as input data for Principal Component Analysis; thus, to select the most promising probiotic isolates. Three isolates (L. brevis PLA2, L. paracasei PLA8 and L. brevis PLA16) were found to be most technological relevant and promising probiotic candidates in comparison to commercial probiotic strains. L. brevis PLA2 was selected as best isolate with probiotic potential by in vitro adherence to the human intestinal HT-29 cell line.

Probiotic potentials of yeasts isolated from some cereal-based Nigerian traditional fermented food products

AIMS

To determine the starter culture and multifunctional potentials of yeast strains from some cereal-based Nigerian traditional fermented food products.

METHODS AND RESULTS

Yeast isolates were screened for enzyme production and identified by sequencing the D1/D2 region of 26S rDNA. Pichia kluyveri LKC17, Issatchenkia orientalis OSL11, Pichia kudriavzevii OG32, Pichia kudriavzevii ROM11 and Candida tropicalis BOM21 exhibited the highest protease, lipase and phytase activity. They were selected and further evaluated for gastrointestinal survival and adherence ability. Although strain-specific, they retained viability at 37°C and showed survival at pH 2·0., I. orientalis OSL11 showed the highest survival at 2% bile salts concentration and P. kudriavzevii ROM11 showed the least survival. The yeast strains showed strong autoaggregation ability (81·24-91·85%) and hydrophobicity to n-hexadecane (33·61-42·30%). The highest co-aggregation ability was detected for P. kudriavzevii OG32 and Escherichia coli (71·57%). All the yeast strains removed cholesterol in the range of 49·03-74·05% over 48 h and scavenged for free radicals in methanol reaction system.

CONCLUSIONS

In this study, we isolated new yeast strains with multifunctional potentials that can be used as functional starter cultures to produce cereal-based probiotic products.

SIGNIFICANCE AND IMPACT OF THE STUDY

The development of probiotic yeast strains as starter culture to improve the quality attributes and confer functional value on cereal-based traditional fermented foods is beneficial.

Molecular analysis and clinical significance of Lactobacillus spp. recovered from clinical specimens presumptively associated with disease

Lactobacillus spp. are part of the normal human flora and are generally assumed to be nonpathogenic. We determined the genotypic identification of >100 Lactobacillus isolates from clinical specimens in the context of presumed pathogenic potential (e.g., recovered as the single/predominant isolate from a sterile site or at ≥10(5) CFU/ml from urine). This study assessed the clinical significance and the frequency of occurrence of each Lactobacillus sp. We identified 16 species of Lactobacillus by 16S rRNA gene sequence analysis, 10 of which could not be associated with disease. While Lactobacillus rhamnosus, Lactobacillus gasseri, and Lactobacillus paracasei were associated with infections, L. gasseri was also a common colonizing/contaminating species. Lactobacillus casei, Lactobacillus johnsonii, and Lactobacillus delbrueckii were associated with at least one infection. Species commonly used in probiotic products (e.g., L. rhamnosus and L. casei) were identical, by 16S rRNA gene sequencing, to our isolates associated with disease. Human isolates of Lactobacillus spp. have differing site associations and levels of clinical significance. Knowing the niche and pathogenic potential of each Lactobacillus sp. can be of importance to both clinical microbiology and the food and probiotic supplement industry.

Beneficial effects of probiotics in upper respiratory tract infections and their mechanical actions to antagonize pathogens

Probiotics are live micro‐organisms with beneficial effects on human health, which have the ability to counteract infections at different locations of the body. Clinical trials have shown that probiotics can be used as preventive and therapeutic agents in upper respiratory tract infections (URTIs) and otitis. Their mechanical properties allow them to aggregate and to compete with pathogens for nutrients, space and attachment to host cells. Consequently, they can directly antagonize pathogens and thus exert beneficial effects without directly affecting the metabolism of the host. An overview of the probiotics with such traits, tested up to date in clinical trials for the prevention or treatment of URTIs and otitis, is presented in this review. Their mechanical properties in the respiratory tract as well as at other locations are also cited. Species with interesting in vitro properties towards pharyngeal cells or against common respiratory pathogens have also been included. The potential safety risks of the cited species are then discussed. This review could be of help in the screening of probiotic strains with specific mechanical properties susceptible to have positive effects in clinical trials against URTIs.

Lactobacillus plantarum prevents bacterial translocation in rats following ischemia and reperfusion injury

BACKGROUND

Bacterial translocation is considered a major cause of initiation and development of systemic sepsis and multiple organ dysfunction in clinic. The aim of this study was to determine the ability of a defined Lactobacillus plantarum to prevent ischemia/reperfusion (I/R) induced intestinal infection.

METHODS

Female Sprague-Dawley rats were randomly allocated into three groups: (1) controls (sham-operated, no treatment), (2) ischemia/reperfusion and (3) ischemia/reperfusion and Lactobacillus plantarum treatment. Lactobacillus plantarum L2 was administered daily intragastrically 14 days prior to induction of I/R. Rats were then sacrificed, and tissue and blood samples were cultured to determine bacterial translocation. Cytokines in plasma were detected by ELISA. Ileal segments were removed for morphological examination.

RESULTS

Intestinal I/R induced excess pro-inflammatory cytokine secretion and barrier dysfunction (increased epithelial cell apoptosis, cecal flora dysbiosis, disruption of mucosa and multiple erosions) in the intestine, associated with increased bacterial translocation to extraintestinal sites. Approximately 87.5% of rats exposed to I/R had bacterial translocation while there was no bacterial translocation in controls. However, pretreatment of animals with Lactobacillus plantarum completely prevented I/R induced bacterial translocation, reduced pro-inflammatory cytokine release, and intestinal epithelial cell apoptosis, resulting in recovered microflora and mucosal integrity.

CONCLUSIONS

These findings indicate that Lactobacillus plantarum L2 can prevent I/R-induced bacterial translocation and intestinal barrier dysfunction and, thereby, exert beneficial effects in the intestinal tract.

Microbial biosurfactants production, applications and future potential

Microorganisms synthesise a wide range of surface-active compounds (SAC), generally called biosurfactants. These compounds are mainly classified according to their molecular weight, physico-chemical properties and mode of action. The low-molecular-weight SACs or biosurfactants reduce the surface tension at the air/water interfaces and the interfacial tension at oil/water interfaces, whereas the high-molecular-weight SACs, also called bioemulsifiers, are more effective in stabilising oil-in-water emulsions. Biosurfactants are attracting much interest due to their potential advantages over their synthetic counterparts in many fields spanning environmental, food, biomedical, and other industrial applications. Their large-scale application and production, however, are currently limited by the high cost of production and by limited understanding of their interactions with cells and with the abiotic environment. In this paper, we review the current knowledge and the latest advances in biosurfactant applications and the biotechnological strategies being developed for improving production processes and future potential.

Possible role of reactive chlorine in microbial antagonism and organic matter chlorination in terrestrial environments

Several studies have demonstrated that extensive formation of organically bound chlorine occurs both in soil and in decaying plant material. Previous studies suggest that enzymatic formation of reactive chlorine outside cells is a major source. However, the ecological role of microbial-induced extracellular chlorination processes remains unclear. In the present paper, we assess whether or not the literature supports the hypothesis that extracellular chlorination is involved in direct antagonism against competitors for the same resources. Our review shows that it is by no means rare that biotic processes create conditions that render biocidal concentrations of reactive chlorine compounds, which suggest that extracellular production of reactive chlorine may have an important role in antagonistic microbial interactions. To test the validity, we searched the UniprotPK database for microorganisms that are known to produce haloperoxidases. It appeared that many of the identified haloperoxidases from terrestrial environments are originating from organisms that are associated with living plants or decomposing plant material. The results of the in silico screening were supported by various field and laboratory studies on natural chlorination. Hence, the ability to produce reactive chlorine seems to be especially common in environments that are known for antibiotic-mediated competition for resources (interference competition). Yet, the ability to produce haloperoxidases is also recorded, for example, for plant endosymbionts and parasites, and there is little or no empirical evidence that suggests that these organisms are antagonistic.

Current concepts of molecular defence mechanisms operative during urinary tract infection

Mucosal tissues such as the gastrointestinal tract are typically exposed to a tremendous number of microorganisms and many of them are potentially dangerous to the host. In contrast, the urogenital tract is rather infrequently colonized with bacterial organisms and also devoid of physical barriers as a multi-layered mucus or ciliated epithelia, thereby necessitating separate host defence mechanisms. Recurrent urinary tract infection (UTI) represents the successful case of microbial host evasion and poses a major medical and economic health problem. During recent years considerable advances have been made in our understanding of the mechanisms underlying the immune homeostasis of the urogenital tract. Hence, the system of pathogen-recognition receptors including the Toll-like receptors (TLRs) is able to sense danger signalling and thus activate the host immune system of the genitourinary tract. Additionally, various soluble antimicrobial molecules including iron-sequestering proteins, defensins, cathelicidin and Tamm-Horsfall protein (THP), as well as their role for the prevention of UTI by modulating innate and adaptive immunity, have been more clearly defined. Furthermore, signalling mediators like cyclic adenosine monophosphate (cAMP) or the circulatory hormone vasopressin were shown to be involved in the defence of uropathogenic microbes and maintenance of mucosal integrity. Beyond this, specific receptors e.g. CD46 or beta1/beta 3-integrins, have been elucidated that are hijacked by uropathogenic E. coli to enable invasion and survival within the urogenital system paving the way for chronic forms of urinary tract infection. Collectively, the majority of these findings offer novel avenues for basic and translational research implying effective therapies against the diverse forms of acute and chronic UTI.

The influence of Lactobacillus acidophilus-derived surfactants on staphylococcal adhesion and biofilm formation

The ability of surfactants obtained from three Lactobacillus acidophilus strains to inhibit Staphylococcus aureus and S. epidermidis biofilms was evaluated. Their influence was determined on bacterial initial adhesion, biofilm formation and dispersal using MTT-reduction assay, confocal laser scanning microscopy and image PHLIP analysis. The number of adhering S. aureus and S. epidermidis cells after a 3-h co-incubation with biosurfactants was reduced by 5-56 % in a strain-and dose-dependent manner. S. epidermidis-and, to a lower extent, in S. aureus-biofilm formation was also inhibited in the presence of the tested surfactants. The addition of surfactants to preformed mature biofilms accelerated their dispersal, and changed the parameters of biofilm morphology. The L. acidophilus-derived surfactants inhibit bacterial deposition rate and biofilm development (and also its maturation) without affecting cell growth probably due to the influence on the cell-surface hydrophobicity of staphylococci.

Adhesive capability of Lactobacillus plantarum 299v is important for preventing bacterial translocation in endotoxemic rats

The preventive effect of the probiotic Lactobacillus plantarum 299v on bacterial translocation (BT) and the role of adhesion were studied in septic rats. Five groups of rats were pretreated as follows: negative and positive control groups received regular drinking water; the oatmeal group received drinking water mixed with oatmeal; the Lp 299v group received drinking water mixed with oatmeal containing 10(9) colony-forming units (CFU) L. plantarum 299v/ml; the Lp 299v-adh(-) group received drinking water with oatmeal containing 10(9) CFU/ml of modified L. plantarum 299v (L. plantarum 299v-adh(-)) lacking adhesive properties to enterocytes. On day 8, all rats except the negative control group were given lipopolysaccharide (LPS) intraperitoneally. After 24 h, mesenteric lymph node (MLN), liver and ileum were harvested for culture. Incidence of BT after LPS challenge was 25% and 88% in MLN and liver, respectively. BT increased to 75% in MLN and 100% in liver of endotoxemic rats pretreated with oatmeal. Pretreatment with L. plantarum 299v reduced BT to 0% and 12% in MLN and liver, respectively. L. plantarum 299v-adh(-) did not prevent BT to MLN. Flow cytometry revealed reduced adherence of these bacteria to intestinal epithelial cells compared to L. plantarum 299v. Thus, L. plantarum 299v prevents BT in septic rats, an effect probably dependent on bacterial adherence to the intestinal mucosa. Further, our findings indicate that oatmeal (prebiotics) without probiotics does not prevent BT during sepsis.

Beneficial lactobacilli in food and feed: long-term use, biodiversity and proposals for specific and realistic safety assessments

Lactobacilli have played a crucial role in the production of fermented products for millennia. Their probiotic effects have recently been studied and used in new products. Isolated cases of lactobacillemia have been reported in at-risk populations, but lactobacilli present an essentially negligible biological risk. We analyzed the current European guidelines for safety assessment in food/feed and conclude that they are not relevant for the Lactobacillus genus. We propose new specific guidelines, beginning by granting a 'long-standing presumption of safety' status to Lactobacillus genus based on its long history of safe use. Then, based on the available body of knowledge and intended use, only such tests as are useful will be necessary before attributing 'qualified presumption of safety' status.