Photoacoustic discrimination of antibiotic-resistant and sensitive Staphylococcus aureus isolates

OBJECTIVES

Bacteremia is a serious and potentially lethal condition. Staphylococcus aureus is a leading cause of bacteremia and methicillin-resistant S. aureus (MRSA) accounts for more than a third of the cases. Compared to methicillin-sensitive S. aureus, MRSA is more than twice as likely to be fatal. Furthermore, subpopulations of seemingly isogenic bacteria may exhibit a range of susceptibilities, often called heterogenous resistance. These heterogeneous antibiotic-resistant infections are often misdiagnosed as hospital-acquired secondary infections because there are no clinically used tests that can differentiate between homogeneous and heterogeneous antibiotic resistance. We describe the development and proof of concept of rapid bacterial identification using photoacoustic flow cytometry and labeled bacteriophages with the characterization and differentiation of heterogeneous antibiotic-resistant bacterial infections.

METHODS

In photoacoustic flow cytometry, pulsed laser light is delivered to a sample flowing past a focused transducer and particles that absorb laser light create an acoustic response. Optically labeled bacteriophage are added to a bacterial mixture that flows through the photoacoustic chamber. The presence of target bacteria is determined by bound labeled phage which are detected photoacoustically. Incubation of bacterial samples in the presence and absence of the antibiotic daptomycin creates a difference in bacterial cell numbers that is quantified using photoacoustic flow cytometry.

RESULTS

Four clinical isolates were tested in the presence and absence of daptomycin. Photoacoustic events for each isolate were recorded and compared to growth curves. Samples treated with daptomycin fell into three categories: resistant, susceptible, and heterogeneous resistant.

CONCLUSIONS

Here we show a method to determine the presence of bacteria as a marker for bloodstream infection level and antibiotic sensitivity in less than 4 hours. Additionally, these results show an ability to identify heterogeneous resistant strains that are often misidentified.

International registry on the use of the CytoSorb® adsorber in ICU patients : Study protocol and preliminary results

INTRODUCTION

The aim of this clinical registry is to record the use of CytoSorb® adsorber device in critically ill patients under real-life conditions.

METHODS

The registry records all relevant information in the course of product use, e. g., diagnosis, comorbidities, course of the condition, treatment, concomitant medication, clinical laboratory parameters, and outcome (ClinicalTrials.gov Identifier: NCT02312024). Primary endpoint is in-hospital mortality as compared to the mortality predicted by the APACHE II and SAPS II score, respectively.

RESULTS

As of January 30, 2017, 130 centers from 22 countries were participating. Data available from the start of the registry on May 18, 2015 to November 24, 2016 (122 centers; 22 countries) were analyzed, of whom 20 centers from four countries provided data for a total of 198 patients (mean age 60.3 ± 15.1 years, 135 men [68.2%]). In all, 192 (97.0%) had 1 to 5 Cytosorb® adsorber applications. Sepsis was the most common indication for CytoSorb® treatment (135 patients). Mean APACHE II score in this group was 33.1 ± 8.4 [range 15-52] with a predicted risk of death of 78%, whereas the observed mortality was 65%. There were no significant decreases in the SOFA scores after treatment (17.2 ± 4.8 [3-24]). However interleukin-6 levels were markedly reduced after treatment (median 5000 pg/ml before and 289 pg/ml after treatment, respectively).

CONCLUSIONS

This third interim report demonstrates the feasibility of the registry with excellent data quality and completeness from 20 study centers. The results must be interpreted with caution, since the numbers are still small; however the disease severity is remarkably high and suggests that adsorber treatment might be used as an ultimate treatment in life-threatening situations. There were no device-associated side effects.

Management of fluid balance in CRRT: a technical approach

BACKGROUND

The possibility of making fluid balance errors during continuous renal replacement therapy has been identified since the beginning of this modality of treatment. The advent of automated machines has partially overcome this problem. Nevertheless, there are conditions and operation modes in which the potential for fluid balance errors is still present.

OBJECTIVE

To analyse fluid balance management in CRRT therapies across a range of currently marketed machine.

METHODS

The tests were conducted in vitro, utilizing saline solution for the blood circuit and regular dialysate/reinfusate for the dialysate/reinfusion circuit. The methodology used was based on the voluntary creation of a fluid balance error by altering the correct flow in the circuit of the different machines. Subsequently, the time for alarm occurrence and the threshold value for fluid balance error was evaluated. The alarm was overridden and the overall fluid error allowed by the machine was evaluated. Each machine was tested in conditions of different dialysate/filtrate flow rates and in different simulated treatment modalities.

RESULTS

Fluid balance errors can be easily avoided not only by a correct and careful adherence to the protocols of use of the current CRRT machines, but also by the compliance to prescriptions and programmed controls during therapy. Most importantly, if an alarm appears on the machine, one can try to override it without major problems; major problems may occur when multiple override commands are operated without identifying the problem and solving it adequately.

CONCLUSION

Machines seem to be designed with adequate safety features and accurate alarm systems. However, features and alarms can be manipulated by operators creating the opportunity for serious error. Physicians and nurses involved in prescription and delivery of CRRT should have precise protocols and defined procedures in relation to machine alarms to prevent major clinical problems.

Effects of surgically induced weight loss on urinary bladder pressure, sagittal abdominal diameter and obesity co-morbidity

OBJECTIVE

Evaluate the effects of surgically induced weight loss on intra-abdominal pressure at one year, reflected in urinary bladder pressure, central obesity, measured by sagittal abdominal diameter and obesity co-morbidity.

DESIGN

Prospective, non-randomized trial.

SETTING

University Hospital, Operating Room, In-patient, Outpatient Clinics.

SUBJECTS

Gastric bypass in 15 severely obese patients.

MEASUREMENTS

Patients underwent pre-operative assessment of weight, body mass index (BMI), co-morbid history, urinary bladder pressure and sagittal abdominal diameter. Patients were reassessed one year after gastric bypass with repeat measurement of weight, bladder pressure, and sagittal abdominal diameter and assessment of co-morbidity.

RESULTS

There were significant (P < 0.001) decreases in weight (140+/-8 - 87+/-6 kg), BMI (52+/-3 - 33+/-2 kg/m2), sagittal abdominal diameter (32+/-1 - 20+/-2 cm), urinary bladder pressure (17+/-2 - 10+/-1 cm H2O) and obesity related problems per patient (2.9+/-0.4 - 1+/-0.2) one year after gastric bypass, with 69+/-4% loss of excess weight.

CONCLUSIONS

Increased sagittal abdominal diameter is associated with increased intra-abdominal pressure which contributes to obesity related co-morbidity. Weight loss following gastric bypass decreases abdominal pressure, sagittal abdominal diameter and obesity co-morbidity.

Traumatic superior mesenteric artery--portal vein fistula

An interesting and rare case of traumatic superior mesenteric artery-to-portal vein arteriovenous fistula is presented. Initial operative control of the bleeding superior mesenteric artery injury required ligation of the superior mesenteric artery at its origin to prevent exsanguination in an extremely unstable patient with multiple injuries. Early postoperative visceral arteriography documented ligation of the superior mesenteric artery with a proximal superior mesenteric artery-to-portal vein arteriovenous fistula. Percutaneous catheter embolization of the arteriovenous fistula was undertaken successfully at this time. Superior mesenteric artery ligation was surprisingly well tolerated. Major arterioportal fistulas require treatment to prevent long-term complications of intestinal ischemia, portal hypertension, and cirrhosis. Although traditional treatment involves ligation of the arteriovenous fistula and arterial bypass, percutaneous embolization is becoming a viable alternative. Arteriography remains the cornerstone of diagnosis and treatment planning.

Neural control of acid-induced serotonin release from rabbit duodenum

The neural mediation of acid-stimulated serotonin release was studied in isolated sheets of rabbit duodenal mucosa mounted in Ussing chambers. The serosal side of the mucosa was exposed to Ringer-HCO3 at pH 7.4, and the mucosal side was exposed to citrate-phosphate buffer at pH 3-6.8. Immunoreactive serotonin release occurred onto the luminal surface at pH 6 and below and onto the serosal surface at pH 5 and below, but was greater on the luminal side at each pH. The effect of cholinergic and adrenergic agonists and antagonists on mucosal serotonin release was measured at luminal pH 7.4, 5, and 4. Acid-stimulated luminal release was significantly inhibited by atropine, hexamethonium, and propranolol at pH 4 and 5 but not by phentolamine. Serotonin release was stimulated at pH 7.4 and 4 by carbachol and isoproterenol but not by norepinephrine or nicotine at pH 7.4. It is concluded that acid-induced and nonacid-induced mucosal serotonin release is partly neurally mediated by muscarinic cholinergic and beta-adrenergic mechanisms.

Entamoeba histolytica causes intestinal secretion: role of serotonin

Lysates of the protozoan parasite Entamoeba histolytica altered active electrolyte transport when present on the serosal surface of rabbit ileum and rat colon. The lysate-induced effects on electrolyte transport were similar to those caused by serotonin, and were blocked by bufotenine, an analog known to inhibit the action of serotonin. The transport effects were partially inhibited by antibody to serotonin. The amebic lysates were shown to contain serotonin by radioimmunoassay, high-performance liquid chromatography, and thin-layer chromatography. These results suggest that the serotonin present in Entamoeba histolytica may be important in the diarrhea seen in amebiasis.

Candida infections in surgical patients

Serious Candida infections were seen in 55 surgical patients from January 1977 through December 1980. Most of the patients had compromising underlying conditions and many were elderly. Broad-spectrum antibiotics and total parenteral nutrition (TPN) appeared to predispose patients to Candida infections. Mortality rate from Candida was 38%. A high percentage of patients with positive blood or bile cultures died as a result of Candida infection. Therapy with intravenous amphotericin B was highly effective if given in adequate dosage. No patient receiving more than 200 mg of amphotericin B died, but the mortality rate was 56% in those receiving lower doses.