Hyperthermic enhancement of serum antimicrobial activity: mechanism by which fever might exert a beneficial effect on the outcome of gram-negative sepsis

Warming up for a better fever: a randomized pilot study in pediatric oncology

BACKGROUND

Fever in children is a major problem in pediatric oncology. Usual management leads to immediate antibiotic and antipyretic therapy, although there is consensus that antipyretic therapy should not be utilized with the sole aim of reducing body temperature. Increased body temperature during fever appears to be an effective modifier in terms of viral replication and enhanced host defense mechanisms against pathogens. Therefore, it might be beneficial to support febrile patients by applying gentle heat during the onset of fever to help the body to reach its new thermoregulatory set point.

METHODS

A randomized pilot study over 6 months will be conducted in a pediatric oncology department in an academic hospital in Germany. This study is a preparation for a multicenter clinical trial with two parallel groups concerning the efficacy of heat application vs. treatment as usual. One of the inclusion criteria is body temperatures ≥ 38.0 °C in n = 24 cases of patients receiving chemotherapy aged 18 months to 17 years. The first intervention consists of gentle heat application with hot water bottles at any sign of illness and onset of fever. The aim is to achieve a warm periphery equilibrated to trunk temperature of less than 0.5 °C. The second intervention is the avoidance of antipyretics. The control group receives the standard antipyretic treatment from the participating hospital. The purposes of this pilot study are proof of principle of intervention, evaluation of safety, feasibility, definition of endpoints, and to receive basic data for sample size calculation and needed resources.

DISCUSSION

The main goal is to improve the care of children with cancer by providing the best possible support for febrile episodes. If fever support by heat reduces discomfort, administration of antipyretics and maybe even antibiotics, this would be an advancement in oncological fever management. This pilot study is intended to provide a basis for a main, multicenter, randomized trial and demonstrate the practicability of heat application in febrile patients in pediatric oncology.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS), DRKS00028273 . Registered on 14 April 2022.

Adjuvant Transgingival Therapy with Visible Light Plus Water-Filtered Infrared-A (VIS + wIRA) in Periodontal Therapy-A Randomized, Controlled, Stratified, Double-Blinded Clinical Trial

The aim of this randomized, controlled, double-blinded clinical trial was to examine the additional healing effect of transgingival visible light and water-filtered infrared-A (VIS + wIRA) in the treatment of periodontitis patients compared with the standard therapy by subgingival instrumentation (SI). Therefore, forty patients with untreated periodontitis received a non-surgical periodontal treatment. Using a split-mouth study design, one quadrant of the upper jaw was randomly either exposed to VIS + wIRA four times for 20 min within two weeks in addition to SI or received only SI. Three and 6 months after intervention, clinical parameters (probing depths (PDs), clinical attachment level, bleeding on probing (BOP), furcation, tooth mobility, plaque control record, and papilla bleeding index) were re-evaluated. In the presence of PD of 4 mm and positive BOP or PD > 4 mm, SI was performed again. Moreover, the patients were asked about their discomfort using a visual analog scale from 1 to 10 for each side of the maxilla. Statistical analysis demonstrated no differences between quadrants at re-evaluation for clinical parameters (p > 0.05) after 3 and 6 months. Concerning pain perception, patients described less pain on the irradiated side (p = 0.016). In the treatment of patients with periodontitis, VIS + wIRA did not show an additional effect on the clinical outcome after 3 and 6 months. Patients described less pain on the irradiated quadrant after treatment.

The Effects of Abnormal Body Temperature on the Prognosis of Patients with Septic Shock

We aimed to use temperature and the area under temperature curve to represent the severity of abnormal body temperature of patients with septic shock and to observe their impact on the prognosis. Five hundred twenty-eight adult patients with septic shock admitted to intensive care unit (ICU) were analyzed. Within the first 24 hours and throughout the period in ICU, the maximum temperature (24hT_max, T_max), lowest temperature (24hT_min, T_min), and the temperature range (24hT_max-min, T_max-min) were aggregated. Patients were divided into the survival group and the death group. Binary logistic regression was used to assess the relationship between body temperature aberrations and survival. The following risk factors of death in 21 days were identified: T_max (odds ratio [OR] 2.967, 95% confidence interval [CI] 1.626-5.414, p < 0.001), T_min (OR 0.337, 95% CI 0.143-0.794, p = 0.013), and T_max-min (OR 3.259, 95% CI 1.847-5.749, p < 0.001). This is an observational study, so one can infer association but not causation. Therefore, we infer that abnormal body temperature is associated with an adverse prognosis in patients with septic shock.

Fever: Views in Anthroposophic Medicine and Their Scientific Validity

Objective. To conduct a scoping review to characterize how fever is viewed in anthroposophic medicine (AM) and discuss the scientific validity of these views. Methods. Systematic searches were run in Medline, Embase, CAMbase, and Google Scholar. Material from anthroposophic medical textbooks and articles was also used. Data was extracted and interpreted. Results. Most of the anthroposophic literature on this subject is in the German language. Anthroposophic physicians hold a beneficial view on fever, rarely suppress fever with antipyretics, and often use complementary means of alleviating discomfort. In AM, fever is considered to have the following potential benefits: promoting more complete recovery; preventing infection recurrences and atopic diseases; providing a unique opportunity for caregivers to provide loving care; facilitating individual development and resilience; protecting against cancer and boosting the anticancer effects of mistletoe products. These views are discussed with regard to the available scientific data. Conclusion. AM postulates that fever can be of short-term and long-term benefit in several ways; many of these opinions have become evidence-based (though still often not practiced) while others still need empirical studies to be validated, refuted, or modified.

Targeted antibiotic delivery using low temperature-sensitive liposomes and magnetic resonance-guided high-intensity focused ultrasound hyperthermia

Chronic non-healing wound infections require long duration antibiotic therapy, and are associated with significant morbidity and health-care costs. Novel approaches for efficient, readily-translatable targeted and localised antimicrobial delivery are needed. The objectives of this study were to 1) develop low temperature-sensitive liposomes (LTSLs) containing an antimicrobial agent (ciprofloxacin) for induced release at mild hyperthermia (∼42 °C), 2) characterise in vitro ciprofloxacin release, and efficacy against Staphylococcus aureus plankton and biofilms, and 3) determine the feasibility of localised ciprofloxacin delivery in combination with MR-HIFU hyperthermia in a rat model. LTSLs were loaded actively with ciprofloxacin and their efficacy was determined using a disc diffusion method, MBEC biofilm device, and scanning electron microscopy (SEM). Ciprofloxacin release from LTSLs was assessed in a physiological buffer by fluorescence spectroscopy, and in vivo in a rat model using MR-HIFU. Results indicated that < 5% ciprofloxacin was released from the LTSL at body temperature (37 °C), while >95% was released at 42 °C. Precise hyperthermia exposures in the thigh of rats using MR-HIFU during intravenous (i.v.) administration of the LTSLs resulted in a four fold greater local concentration of ciprofloxacin compared to controls (free ciprofloxacin + MR-HIFU or LTSL alone). The biodistribution of ciprofloxacin in unheated tissues was fairly similar between treatment groups. Triggered release at 42 °C from LTSL achieved significantly greater S. aureus killing and induced membrane deformation and changes in biofilm matrix compared to free ciprofloxacin or LTSL at 37 °C. This technique has potential as a method to deliver high concentration antimicrobials to chronic wounds.

Activity of antimicrobial drugs against bacterial pathogens under mild hypothermic conditions

BACKROUND

Infections are a common problem in cardiac arrest survivors. Antimicrobial drugs are often administered in routine care during treatment of patients with mild therapeutic hypothermia (MTH). Because there is to date no evidence for the pharmacodynamics of antimicrobial drugs under MTH conditions, we investigated the in vitro activity of common antimicrobials against clinically relevant bacterial pathogens.

MATERIAL AND METHODS

Activities of antimicrobial drugs against clinically relevant bacterial pathogens were assessed in vitro by disk diffusion and broth microdilution assays at normothermic (37°C) and hypothermic (32°C) conditions.

RESULTS

Seventy-three bacterial isolates were tested in disk diffusion and 15 in broth microdilution assays. Mean differences in zone diameters and minimal inhibitory concentration ratios were 0.6 mm (95% confidence interval, 0.3-0.9 mm) and 0.98 (95% confidence interval, 0.95-1.02), respectively, meeting predefined criteria for equivalence of in vitro antimicrobial activity.

CONCLUSIONS

The presented data provide reassuring evidence that the intrinsic activity of antimicrobials seems to be unaltered in MTH. However, further studies evaluating the pharmacokinetics including target site concentrations of the respective drugs and in vivo pharmacodynamics are necessary to complement our understanding of the appropriate use of antimicrobials in MTH.

Microbial growth inhibition by alternating electric fields in mice with Pseudomonas aeruginosa lung infection

High-frequency, low-intensity electric fields generated by insulated electrodes have previously been shown to inhibit bacterial growth in vitro. In the present study, we tested the effect of these antimicrobial fields (AMFields) on the development of lung infection caused by Pseudomonas aeruginosa in mice. We demonstrate that AMFields (10 MHz) significantly inhibit bacterial growth in vivo, both as a stand-alone treatment and in combination with ceftazidime. In addition, we show that peripheral (skin) heating of about 2 degrees C can contribute to bacterial growth inhibition in the lungs of mice. We suggest that the combination of alternating electric fields, together with the heat produced during their application, may serve as a novel antibacterial treatment modality.

Bacterial infections in anorexia nervosa: delayed recognition increases complications

OBJECTIVE

We compared the natural history of bacterial infection in patients with anorexia nervosa (AN) with controls, and assessed which of a range of patient characteristics were associated with infection, fever response, and the rate of infectious complications in AN patients.

METHOD

The charts of 311 consecutive hospital admissions of AN patients were reviewed. Patients who had a bacterial infection while in the hospital were compared with the AN patients who did not have an infection, with respect to a range of demographic and disease variables. Fever response and infection complication rate also were evaluated in AN patients with a bacterial infection and in nonanorectic control subjects admitted with a bacterial infection.

RESULTS

AN patients with a bacterial infection showed a reduced fever response, were often difficult to diagnose because of fewer signs and symptoms, and infection became more frequent with increasing patient age.

DISCUSSION

A reduction in fever response and the signs and symptoms of infection significantly delayed diagnosis in AN patients and increased the complication rate from bacterial infection. We recommend that an increased index of suspicion and an early complete blood count and bacteriologic cultures be adopted for the investigation of bacterial infection in AN patients.

“Starve a fever and feed a cold”: feeding and anorexia may be adaptive behavioral modulators of autonomic and T helper balance

Anorexia is a common symptom accompanying infections, but the teleology of the phenomenon remains unexplained. We hypothesize that anorexia may represent a prehistoric behavioral adaptation to fight infection by maintaining T helper (Th)2 bias, which is particularly vital in fighting bacterial pathogens. Specifically, we propose that anorexia may avert the reduction of Th2/Th1 ratio by preventing feeding-induced neurohormonal and vagal output from the gut. Emerging evidence suggests that the vagal and neurohormonal output of the gut during feeding promotes Th1 function, which is desirable in fighting viral infections. Since fever may be an adaptation to fight bacteria and "colds" are generally viral in origin, the adage "starve a fever and feed a cold" may reflect a sensible behavioral strategy to tilt autonomic and Th balance in directions that are optimal for fighting the particular type of infection. The ability to modulate T helper balance through the neurohormonal and autonomic axis by adjusting food intake may be the mechanism behind other unexplained clinical observations such as the improved outcomes of ICU patients after enteric versus parenteric feedings. Compared to the prehistoric period when bacterial infection was commonplace, the anorexic response may be less adaptive today when viruses and cancers have become common triggers of anorexia. By promoting host anorexia, cachexia, and insomnia, cancers and viruses can deter behaviors such as digestion and sleep that would raise vagal and Th1 activity against tumors and viruses. Hydration and sleep, unexplained but widely accepted recommendations for flu patients, may also work by promoting vagal and Th1 functions. Modulating feeding, hydration, and sleep may prove beneficial in treating other conditions associated with abnormal autonomic and Th balance.

Predicting bacteremia and bacteremic mortality in liver transplant recipients

Predictors of bacteremia and mortality in bacteremic liver transplant recipients were prospectively assessed. One hundred eleven consecutive episodes of fever or infections were documented in 59 patients over a 4-year period. Forty-nine percent (29 of 59 patients) of the patients had bacteremia, 39% (23 of 59 patients) had nonbacteremic infections, and 12% (7 of 59 patients) had fever of noninfectious cause. Primary (catheter-related) bacteremia (31%; 9 of 29 patients), pneumonia (24%; 7 of 29 patients), abdominal and/or biliary infections (14%; 4 of 29 patients), and wound infections (10%; 3 of 29 patients) were the predominant sources of bacteremia. Diabetes mellitus (odds ratio, 6.9; P =.03) and serum albumin level less than 3.0 mg/dL (odds ratio, 0.14; P =.02) were independently significant predictors of bacteremia compared with nonbacteremic infections. Mortality at 14 days was 28% (8 of 29 patients) in those with bacteremia compared with 4% (1 of 23 patients) in those with nonbacteremic infections and 0% (0 of 7) in patients with fever of noninfectious cause (P =.03). Intensive care unit stay at the time of bacteremia (100% v 47%; P =.005), absence of chills (0% v 53%; P =.005), lower temperature at the onset of bacteremia (99.2 degrees F v 101.5 degrees F; P =.009), lower maximum temperature during the course of bacteremia (99.3 degrees F v 102 degrees F, P =.008), greater serum bilirubin level (7.6 v 1.5 mg/dL; P =.024), presence of abnormal blood pressure (80% v 16%; P =. 0013), and greater prothrombin time (15.6 v 13.3 seconds; P =.013) were significantly predictive of greater mortality in the bacteremic patients. These data have implications for discerning the likelihood of bacteremia and initiation of empiric antibiotics pending cultures. Lack of febrile response in bacteremic liver transplant recipients portended a poorer outcome.

Treatment of fever in childhood

Although the need for routine antipyretic therapy in children has often been questioned, there are no data to contra-indicate this. Not all fevers need to be treated but many physicians do so to relieve parental concern. The most commonly used antipyretic drugs are acetylsalicylic acid (ASA), paracetamol (acetaminophen) and dipyrone (metamizol). Paracetamol and ASA have been extensively evaluated but there are few clinical trials on dipyrone. In the last decade a strong statistical association has been observed between salicylates and Reye syndrome. Paracetamol is the most common cause of acute hepatic failure. Dipyrone has been associated with agranulocytosis. In the light of these findings the extensive use of antipyretics drugs has been seriously questioned.

Fever and the control of gram-negative bacteria

Although it seems obvious that fever has some important general adaptive value, it is still not clear by what means this function is manifested. One postulate is that febrile conditions result in the sequestration of soluble iron, effectively starving some pathogens of that essential nutrient. On the basis of our recent experiments, we propose a new mechanism for how fever serves to restrict a wide range of Gram-negative bacteria. The elevated temperature prevents the bacteria from synthesizing their protective LPS, thereby enabling serum complement to perforate and kill the invading pathogens even prior to the production of host antibodies.

Differential acute-phase responses in febrile and cold- and heat-exposed rabbits

Endotoxin (LPS) characteristically provokes both fever and the acute-phase reaction (APR). The present studies were undertaken to determine whether these two responses are mutually dependent or controlled separately. Rabbits were injected with LPS (2 micrograms/kg, IV) or exposed to heat (37 +/- 1 degree C) such that the patterns and magnitudes of the body temperature (Tco) rises (1.6 +/- 0.5 degrees C) were similar. While the plasma levels of Fe and Zn decreased, and those of Cu and N-acetylneuraminic acid (NANA) increased significantly after LPS-induced fever, no such changes occurred after heat-induced hyperthermia. In subsequent study, different rabbits were exposed to cold (3 +/- 1 degree C), first furred, then sheared. While furred, they thermoregulated by cutaneous vasoconstriction, whereas, while shaved, they additionally increased their metabolic rates. However, in neither case were the plasma levels of Fe, Zn, Cu, or NANA different in comparison to their pre-cooling values (Ta = 22 +/- 1 degree C). It would seem, therefore, that the acute-phase blood responses to LPS (and ultimately, to endogenous pyrogen [EP]) probably are not mediated merely by the rise in the Tco or by the concomitantly induced vascular and/or thermogenic effectors of fever; but rather, the APR appears to be a regulated, separate response to LPS/EP.