Fever-like temperature impacts on Staphylococcus aureus and Pseudomonas aeruginosa interaction, physiology, and virulence both in vitro and in vivo

BACKGROUND

Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) cause a wide variety of bacterial infections and coinfections, showing a complex interaction that involves the production of different metabolites and metabolic changes. Temperature is a key factor for bacterial survival and virulence and within the host, bacteria could be exposed to an increment in temperature during fever development. We analyzed the previously unexplored effect of fever-like temperatures (39 °C) on S. aureus USA300 and P. aeruginosa PAO1 microaerobic mono- and co-cultures compared with 37 °C, by using RNAseq and physiological assays including in vivo experiments.

RESULTS

In general terms both temperature and co-culturing had a strong impact on both PA and SA with the exception of the temperature response of monocultured PA. We studied metabolic and virulence changes in both species. Altered metabolic features at 39 °C included arginine biosynthesis and the periplasmic glucose oxidation in S. aureus and P. aeruginosa monocultures respectively. When PA co-cultures were exposed at 39 °C, they upregulated ethanol oxidation-related genes along with an increment in organic acid accumulation. Regarding virulence factors, monocultured SA showed an increase in the mRNA expression of the agr operon and hld, pmsα, and pmsβ genes at 39 °C. Supported by mRNA data, we performed physiological experiments and detected and increment in hemolysis, staphyloxantin production, and a decrease in biofilm formation at 39 °C. On the side of PA monocultures, we observed an increase in extracellular lipase and protease and biofilm formation at 39 °C along with a decrease in the motility in correlation with changes observed at mRNA abundance. Additionally, we assessed host-pathogen interaction both in vitro and in vivo. S. aureus monocultured at 39οC showed a decrease in cellular invasion and an increase in IL-8-but not in IL-6-production by A549 cell line. PA also decreased its cellular invasion when monocultured at 39 °C and did not induce any change in IL-8 or IL-6 production. PA strongly increased cellular invasion when co-cultured at 37 and 39 °C. Finally, we observed increased lethality in mice intranasally inoculated with S. aureus monocultures pre-incubated at 39 °C and even higher levels when inoculated with co-cultures. The bacterial burden for P. aeruginosa was higher in liver when the mice were infected with co-cultures previously incubated at 39 °C comparing with 37 °C.

CONCLUSIONS

Our results highlight a relevant change in the virulence of bacterial opportunistic pathogens exposed to fever-like temperatures in presence of competitors, opening new questions related to bacteria-bacteria and host-pathogen interactions and coevolution.

Fever-like temperature impacts on Staphylococcus aureus and Pseudomonas aeruginosa interaction, physiology, and virulence both in vitro and in vivo

Background

Staphylococcus aureus and Pseudomonas aeruginosa cause a wide variety of bacterial infections and coinfections, showing a complex interaction that involves the production of different metabolites and metabolic changes. Temperature is a key factor for bacterial survival and virulence and within the host, bacteria could be exposed to an increment in temperature during fever development. We analyzed the previously unexplored effect of fever-like temperatures (39°C) on S. aureus USA300 and P. aeruginosa PAO1 microaerobic mono- and co-cultures compared with 37°C, by using RNAseq and physiological assays including in-vivo experiments.

Results

In general terms both temperature and co-culturing had a strong impact on both PA and SA with the exception of the temperature response of monocultured PA. We studied metabolic and virulence changes on both species. Altered metabolic features at 39°C included arginine biosynthesis and the periplasmic glucose oxidation in S. aureus and P. aeruginosa monocultures respectively. When PA co-cultures were exposed at 39°C they upregulated ethanol oxidation related genes along with an increment in organic acid accumulation. Regarding virulence factors, monocultured SA showed an increase in the mRNA expression of the agr operon and hld, pmsα and pmsβ genes at 39°C. Supported by mRNA data, we performed physiological experiments and detected and increment in hemolysis, staphylxantin production and a decrease in biofilm formation at 39°C. On the side of PA monocultures, we observed increase in extracellular lipase and protease and biofilm formation at 39°C along with a decrease in motility in correlation with changes observed at mRNA abundance. Additionally, we assessed host-pathogen interaction both in-vitro and in-vivo . S. aureus monocultured at 39°C showed a decrease in cellular invasion and an increase in IL-8 -but not in IL-6- production by A549 cell line. PA also decreased its cellular invasion when monocultured at 39°C and did not induce any change in IL-8 or IL-6 production. PA strongly increased cellular invasion when co-cultured at 37°C and 39°C. Finally, we observed increased lethality in mice intranasally inoculated with S. aureus monocultures pre-incubated at 39°C and even higher levels when inoculated with co-cultures. The bacterial burden for P. aeruginosa was higher in liver when the mice were infected with co-cultures previously incubated at 39°C comparing with 37°C.

Conclusion

Our results highlight a relevant change in the virulence of bacterial opportunistic pathogens exposed to fever-like temperatures in presence of competitors, opening new questions related to bacteria-bacteria and host-pathogen interactions and coevolution.

Harnessing Behavioral Economics Principles to Promote Better Surgeon Accountability for Operating Room Cost: A Prospective Study

BACKGROUND

Operating room (OR) cost accounts for a significant portion of inpatient spending, but most surgeons are unaware of the costs of OR implants and supplies. We leveraged behavioral economics principles and a cost transparency tool to have an impact on discretionary OR spending (disposable supplies).

STUDY DESIGN

We performed a single-institution, prospective study, from January to December 2018, across 3 departments: urology, thoracic, and endocrine. Two self-selected procedures per department were subjected to intraoperative supply cost (ISC) feedback via a custom dashboard and monthly email reports. Behavioral economics principles like choice overload, social ranking, and threshold effects were leveraged during study design. The primary outcome of percentage change in the department-level mean ISC, as determined via an interrupted time-series mixed effects model, was compared between the intervention year (2018) and "pre-baseline" (2016) and "baseline" (2017) years.

RESULTS

A total of 2,853 procedures and 26 surgeons comprised our analytical sample. Costs decreased in 5 of the 6 procedures in 2018. On average, there was a significant monthly decrease in costs of approximately 0.5% over the study period (p = 0.0004). Post-intervention, there was a nonsignificant additional decrease of 0.6% in monthly cost (p = 0.0648). Overall cost significantly decreased by 20% due to the intervention (p < 0.0001). Similar results were noted on sensitivity analysis. There were no significant changes in the incidence of postoperative complication due to our intervention.

CONCLUSIONS

Deployment of a cost feedback tool using behavioral economics principles resulted in a significant decrease in OR spending without negatively affecting complication rate.

14 years of experience with the artificial urinary sphincter in children and adolescents without spina bifida

PURPOSE

The efficacy of the artificial urinary sphincter to treat sphincteric incontinence in pediatric patients with spina bifida has been clearly reported. The possibility of maintaining spontaneous voiding has usually been the main reason for prosthetic device surgery. We reviewed our experience with the artificial urinary sphincter in patients without spina bifida who had had previous surgery of the bladder neck or proximal urethra.

MATERIALS AND METHODS

From 1990 to 2004, 112 children and adolescents underwent implantation of an AMS 800 artificial urinary sphincter. Of the patients 19 males and 4 females (20.5%) between ages 4 and 17 years (mean 8.1) had no spina bifida. Instead there were bladder exstrophy in 12 patients, anorectal malformation with a rectourethral or vesical fistula in 7 and epispadias in 4. A bladder neck cuff between 5.5 and 7.5 cm, and a 61-70 balloon were used in all patients.

RESULTS

Only 1 patient was lost to followup. In 22 patients (95.6%) mean followup was 80 months (range 4 to 155). Three sphincters in patients with exstrophy were removed because of erosion and/or infection 5, 49 and 60 months after initial surgery, respectively. A total of 19 sphincters remained in place (86.3% survival rate) with 5 revisions (26.3%) because of the pump (2), the cuff (2) or balloon fluid leakage. In this group 13 patients (68.4%) voided spontaneously and 6 (31.6%) performed clean intermittent catheterization, although 3 also voided spontaneously. Overall continence was good in 87% of patients because 2 were still incontinent at night.

CONCLUSIONS

The artificial urinary sphincter is a good long-term solution to urinary incontinence secondary to sphincter incompetence despite multiple previous surgeries of the bladder neck or proximal urethra. Patients with bladder exstrophy and many previous bladder procedures are more exposed to complications such as erosion compared with patients with epispadias or anorectal malformation. The high percent of patients maintaining spontaneous voiding and the good rate of continence are the most important benefits of this type of surgical option for sphincter incompetence.

Reversible prevention of platelet activation by (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide (ajoene) in dogs under extracorporeal circulation

Ajoene ((E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide), an organosulfur compound derived from garlic inhibits platelet activation induced ex vivo by all known agonists. The effect of ajoene on the thrombocytopenia associated with the circulation of blood through extracorporeal devices such as dialyzers or oxygenators was studied under the following conditions: Ex vivo using fresh, heparinized human blood, circulating through a dialyzer or oxygenator, and in vivo, in dogs subjected to extracorporeal circulation. In both experimental conditions ajoene proved very efficacious in preventing platelet loss (60-65% loss in controls vs. 15-20% loss in the presence of ajoene, p less than 0.01). Moreover, recuperation of platelet function was achieved after 3-4 h in the in vivo experiments.

The molecular basis of the antiplatelet action of ajoene: direct interaction with the fibrinogen receptor

Ajoene, the major antiplatelet compound derived from garlic inhibits the fibrinogen-supported aggregation of washed human platelets (ID50 = 13 microM) and, inhibits binding of 125I-fibrinogen to ADP-stimulated platelets (ID50 = 0.8 microM). In both cases, the inhibition is of the mixed non-competitive type. Furthermore, fibrinogen-induced aggregation of chymotrypsin-treated platelets is also inhibited by ajoene in a dose-dependent manner (ID50 = 2.3 microM). Other membrane receptors such as ADP or epinephrine receptors are not affected by ajoene. Ajoene strongly quenches the intrinsic fluorescence emission of purified glycoproteins IIb-IIIa (ID50 = 10 microM). These results indicate that the antiaggregatory effect of ajoene is causally related to its direct interaction with the putative fibrinogen receptor.

Ajoene, the antiplatelet principle of garlic, synergistically potentiates the antiaggregatory action of prostacyclin, forskolin, indomethacin and dypiridamole on human platelets

Ajoene, the major antiplatelet compound derived from garlic, synergistically potentiates the antiaggregatory action of prostacyclin, forskolin, indomethacin and dypiridamole. For collagen-induced platelet aggregation in human PRP, the ID50 for ajoene is 95 +/- 5 microM. However, in the presence of the antiaggregatory drugs mentioned above, the ID50 for ajoene decreases more than what would be predicted on the basis of simple additive effects. Similarly, the ID50 for prostacyclin decreases from 1 nM to 0.15 nM in the presence of 80 microM ajoene. Isobolic curves for the various combinations of ajoene with prostacyclin or indomethacin exhibit departure from linearity, as predicted for a potentiated synergism between ajoene and these drugs. Dypiridamole, which in PRP has very little effect on the dose-response curve for ajoene, when assayed in whole blood decreases the ID50 for ajoene by a factor of four. These results demonstrate that the antithrombotic potential of ajoene is substantially increased in the presence of physiologically and pharmacologically active antiplatelet agents.