Effect of Phthalates and Their Substitutes on the Physiology of Pseudomonas aeruginosa

Phthalates are used in a variety of applications—for example, as plasticizers in polyvinylchloride products to improve their flexibility—and can be easily released into the environment. In addition to being major persistent organic environmental pollutants, some phthalates are responsible for the carcinogenicity, teratogenicity, and endocrine disruption that are notably affecting steroidogenesis in mammals. Numerous studies have thus focused on deciphering their effects on mammals and eukaryotic cells. While multicellular organisms such as humans are known to display various microbiota, including all of the microorganisms that may be commensal, symbiotic, or pathogenic, few studies have aimed at investigating the relationships between phthalates and bacteria, notably regarding their effects on opportunistic pathogens and the severity of the associated pathologies. Herein, the effects of phthalates and their substitutes were investigated on the human pathogen, Pseudomonas aeruginosa, in terms of physiology, virulence, susceptibility to antibiotics, and ability to form biofilms. We show in particular that most of these compounds increased biofilm formation, while some of them enhanced the bacterial membrane fluidity and altered the bacterial morphology.

POS0188 DISEASE ACTIVITY OUTCOME MEASURES ARE ONLY AVAILABLE IN HALF OF THE ELECTRONIC MEDICAL FILES OF PATIENTS WITH AXIAL SPONDYLOARTHRITIS FOLLOWED IN AN OUTPATIENT CLINIC: THE RESULTS OF AN AUDIT OF A TERTIARY-CARE RHEUMATOLOGY DEPARTMENT

Background:

Current recommendations for management of patients with axial Spondylarthritis (axSpA) include regular collection of validated disease activity outcomes.

Objectives:

This study aimed at evaluating the proportion of patients for whom the elements allowing the calculation of the validated outcome measures were available on the visits reported on the electronic medical records (EMR) and the factors associated with the presence of such information on the EMR.

Methods:

This was a cross-sectional and monocentric observational study conducted in a tertiary-care rheumatology department, EULAR center of excellence and ASAS center. We performed a systematic electronic search among all patients with a SpA diagnosis code who attended an outpatient visit between February 1st, 2018 and February 28th, 2019. Thereafter, a manual search was performed in order to check whether disease activity outcome measures (or the elements allowing its calculation): BASDAI individual questions, Disease activity Global, CRP, BASDAI and ASDAS) were reported on EMR. Patient’s and physician’s demographics disease characteristics (including treatment) and whether the patient had participated in a systematic review were also collected. A descriptive analysis of the percentage of EMR with available outcomes was performed, and the characteristics of patients in whom these measures were available/were not available evaluated by univariable and multivariable analysis (including only variables with p < 0,10 on the univariate)

Results:

320 EMR of axSpA patients seen in the outpatient clinic were screened and selected. Among them, 178 (55.6%) had at least one disease activity outcome measure reported, while 144(45%) and 123 (38.4%) had a BASDAI and an ASDAS reported, respectively. The most frequently reported disease activity items were duration of morning stiffness (n=230, 72%) and CRP (n=224, 70%).

Only previous participation on an educational program for self-assessment was found to be independently associated with a reported disease activity outcome: among the patients participating in such program, 93.1% (n=27/29) had a disease activity measure available, compared to 51.9% (n=151/291) in those who did not participate in such program (p<0.001) (Table 1)

Conclusion:

Implementation of recommendations with regard to regularly collecting disease activity outcome measures is not optimal. The participation in educational programs including self-assessment educational programs might be one of the keys to improve such implementation.

References:

[1]Smolen JS, Braun J, Dougados M, Emery P, Fitzgerald O, Helliwell P, et al. Treating spondyloarthritis, including ankylosing spondylitis and psoriatic arthritis, to target: recommendations of an international task force. Ann Rheum Dis 2014;73:6–16. https://doi.org/10.1136/annrheumdis-2013-203419.

[2]van der Heijde D, Ramiro S, Landewé R, Baraliakos X, Van den Bosch F, Sepriano A, et al. 2016 update of the ASAS-EULAR management recommendations for axial spondyloarthritis. Ann Rheum Dis 2017;76:978–91. https://doi.org/10.1136/annrheumdis-2016-210770.

Figure 1.

Frequency of disease activity measures reporting in the Electronic Medical Record of patients with axial Spondyloarthritis, followed in a tertiary care rheumatology department outpatient clinic

Table 1.

Factors associated with the presence of a reported disease activity measures on the electronic medical file of patients with axial SpA

Disclosure of Interests:

Elodie Portier: None declared, Maxime Dougados: None declared, Christian Roux: None declared, Anna Moltó Consultant of: Abbvie, BMS, MSD, Pfizer, Lilly, UCB Novartis, Grant/research support from: Pfizer

Anti-Biofilm Activity of a Low Weight Proteinaceous Molecule from the Marine Bacterium Pseudoalteromonas sp. IIIA004 against Marine Bacteria and Human Pathogen Biofilms

Pseudoalteromonas bacteria are known as potential bioactive metabolite producers. Because of the need to obtain natural molecules inhibiting the bacterial biofilms, we investigated the biofilm inhibitory activity of the marine bacterium Pseudoalteromonas sp. IIIA004 against the pioneer surface colonizer Roseovarius sp. VA014. The anti-biofilm activity from the culture supernatant of Pseudoalteromonas sp. IIIA004 (SNIIIA004) was characterized in microtiter plates (static conditions/polystyrene surface) and in flow cell chambers (dynamic conditions/glass surface). The Pseudoalteromonas exoproducts exhibited an inhibition of Roseovarius sp. VA014 biofilm formation as well as a strong biofilm dispersion, without affecting the bacterial growth. Microbial adhesion to solvent assays showed that SNIIIA004 did not change the broad hydrophilic and acid character of the Roseovarius strain surface. Bioassay-guided purification using solid-phase extraction and C18 reverse-phase-high-performance liquid chromatography (RP-HPLC) was performed from SNIIIA004 to isolate the proteinaceous active compound against the biofilm formation. This new anti-biofilm low weight molecule (< 3kDa), named P004, presented a wide spectrum of action on various bacterial biofilms, with 71% of sensitive strains including marine bacteria and human pathogens. Pseudoalteromonas sp. IIIA004 is a promising source of natural anti-biofilm compounds that combine several activities.

Iron Availability Modulates the Persistence of Legionella pneumophila in Complex Biofilms

Legionella pneumophila is a pathogenic bacteria found in biofilms in freshwater. Iron is an essential nutrient for L. pneumophila growth. In this study, complex biofilms were developed using river water spiked with L. pneumophila, and the persistence of L. pneumophila in these complex biofilms was evaluated. In order to study the role of iron in the persistence of L. pneumophila, river water was supplied with either iron pyrophosphate or iron chelators (deferoxamine mesylate, DFX for ferric iron and dipyridyl, DIP for ferrous iron) to modulate iron availability. The addition of iron pyrophosphate and DFX did not markedly affect the persistence of L. pneumophila in the biofilms, whereas that of DIP had a beneficial effect. Since DIP specifically chelates ferrous iron, we hypothesized that DIP may protect L. pneumophila from the deleterious effects of ferrous iron. In conclusion, ferrous iron appears to be important for the persistence of L. pneumophila in complex biofilms. However, further studies are needed in order to obtain a better understanding of the role of ferrous iron in the behavior of this bacterium in the environment.

Legionella pneumophila: The Paradox of a Highly Sensitive Opportunistic Waterborne Pathogen Able to Persist in the Environment

Legionella pneumophila, the major causative agent of Legionnaires’ disease, is found in freshwater environments in close association with free-living amoebae and multispecies biofilms, leading to persistence, spread, biocide resistance, and elevated virulence of the bacterium. Indeed, legionellosis outbreaks are mainly due to the ability of this bacterium to colonize and persist in water facilities, despite harsh physical and chemical treatments. However, these treatments are not totally efficient and, after a lag period, L. pneumophila may be able to quickly re-colonize these systems. Several natural compounds (biosurfactants, antimicrobial peptides…) with anti-Legionella properties have recently been described in the literature, highlighting their specific activities against this pathogen. In this review, we first consider this hallmark of Legionella to resist killing, in regard to its biofilm or host-associated life style. Then, we focus more accurately on natural anti-Legionella molecules described so far, which could provide new eco-friendly and alternative ways to struggle against this important pathogen in plumbing.

IroT/mavN, a new iron-regulated gene involved in Legionella pneumophila virulence against amoebae and macrophages

Legionella pneumophila is a pathogenic bacterium commonly found in water. Eventually, it could be transmitted to humans via inhalation of contaminated aerosols. Iron is known as a key requirement for the growth of L. pneumophila in the environment and within its hosts. Many studies were performed to understand iron utilization by L. pneumophila but no global approaches were conducted. In this study, transcriptomic analyses were performed, comparing gene expression in L. pneumophila in standard versus iron restricted conditions. Among the regulated genes, a newly described one, lpp_2867, was highly induced in iron-restricted conditions. Mutants lacking this gene in L. pneumophila were not affected in siderophore synthesis or utilization. On the contrary, they were defective for growth on iron-depleted solid media and for ferrous iron uptake. A sequence analysis predicts that Lpp_2867 is a membrane protein, suggesting that it is involved in ferrous iron transport. We thus named it IroT, for iron transporter. Infection assays showed that the mutants are highly impaired in intracellular growth within their environmental host Acanthamoeba castellanii and human macrophages. Taken together, our results show that IroT is involved, directly or indirectly, in ferrous iron transport and is a key virulence factor for L. pneumophila.

Natural biofilm formation with Legionella pneumophila

Biofilm formation could be studied in various conditions. Most of the studies with Legionella pneumophila used monospecies biofilm in culture media. In some cases, it is important to study bacteria in conditions more close to environmental conditions. In this paper, we describe protocols to produce natural biofilms from river water that were spiked with L. pneumophila.

Piperacillin-tazobactam and netilmicin as a safe and efficacious empirical treatment of febrile neutropenic children

GOALS OF WORK

We evaluated piperacillin-tazobactam in association with netilmicin (TN) in the early empirical treatment of neutropenic children, as data are limited in number.

PATIENTS AND METHOD

In 1996, an observational study was initiated to assess the efficacy and safety of this association, with a glycopeptide (TNG) if needed. The impact on the bacterial ecology of our unit was also observed. Children were treated for hematological malignancy or solid tumor between September 1996 and December 1998 and presented a febrile neutropenia.

RESULTS

There were 148 evaluable febrile neutropenic episodes in 104 patients. Median age was 7 years, 55% of the episodes were fever of unknown origin, 22% were clinically documented and 23% microbiologically documented (27 bacteriemia). A glycopeptide was added in 67 episodes. The initial unmodified treatment was successful in 114 episodes (77%): 75/81 episodes in the TN group and 39/67 in the TNG group. For successful episodes, median treatment duration was 6 days. There were 22 febrile recurrences. These patients, as well as initial failures, always responded to a second-line treatment. One child was considered a failure because he developed a skin rash probably due to piperacillin-tazobactam and required another beta-lactamase.

CONCLUSION

This study suggests that piperacillin-tazobactam in association with netilmicin presents a satisfactory efficacy and a good tolerance as empirical therapy for febrile neutropenic children. It allowed us to maintain the bacterial ecology of our unit.