Fever and aging

Diurnal temperature variation and the implications for diagnosis and infectious disease screening: a population-based study

OBJECTIVES

Fevers have been used as a marker of disease for hundreds of years and are frequently used for disease screening. However, body temperature varies over the course of a day and across individual characteristics; such variation may limit the detection of febrile episodes complicating the diagnostic process. Our objective was to describe individual variation in diurnal temperature patterns during episodes of febrile activity using millions of recorded temperatures and evaluate the probability of recording a fever by sex and for different age groups.

METHODS

We use timestamped deidentified temperature readings from thermometers across the US to construct illness episodes where continuous periods of activity in a single user included a febrile reading. We model the mean temperature recorded and probability of registering a fever across the course of a day using sinusoidal regression models while accounting for user age and sex. We then estimate the probability of recording a fever by time of day for children, working-age adults, and older adults.

RESULTS

We find wide variation in body temperatures over the course of a day and across individual characteristics. The diurnal temperature pattern differed between men and women, and average temperatures declined for older age groups. The likelihood of detecting a fever varied widely by the time of day and by an individual's age or sex.

CONCLUSIONS

Time of day and demographics should be considered when using body temperatures for diagnostic or screening purposes. Our results demonstrate the importance of follow-up thermometry readings if infectious diseases are suspected.

The Association between Tannerella forsythia and the Onset of Fever in Older Nursing Home Residents: A Prospective Cohort Study

Background: Periodontal pathogens are related to the incidence of systemic diseases. This study aimed to examine whether periodontal pathogen burden is associated with the risk of fever onset in older adults. Methods: Older adults in nursing homes, aged ≥65 years, were enrolled. The study was set in Kitakyushu, Japan. The body temperatures of participants were ≥37.2 °C and were recorded for eight months. As periodontal pathogens, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia were qualified by a real-time polymerase chain reaction at the baseline. For statistical analysis, the number of bacterial counts was logarithmically conversed to 10 as a base. Results: Data from 56 participants with a median age of 88 (62−98) years were available for analysis. The logarithmic-conversed bacterial counts of T. forsythia, but not P. gingivalis or T. denticola, were associated with the onset of fever in older residents. The Kaplan−Meier method revealed that the group with <104 of T. forsythia had significantly less cumulative fever incidence than the group with ≥104 of T. forsythia. The group with ≥104 of T. forsythia was associated with an increased risk of fever onset (hazard ratio, 3.7; 98% confidence interval, 1.3−10.2; p = 0.012), which was adjusted for possible confounders. Conclusions: Bacterial burden of T. forsythia in the oral cavity was associated with the risk of the onset of fever in older nursing homes residents.

Posterior teeth occlusion is related independently to onset of fever in residents of aged person welfare facility: Perspective cohort study

BACKGROUND

Onset of fever is a common presentation of symptoms in older adults. Loss of posterior teeth occlusion provokes dysphagia, which is commonly related to infectious diseases of the respiratory tract. However, a correlation between posterior teeth occlusion and the onset of fever has not been studied. The aim of the present study was to investigate whether posterior teeth occlusion is correlated with the onset of fever in residents of aged person welfare facilities.

METHODS

This perspective cohort study was carried out from February 2019 to December 2019 in Kitakyushu, Japan. The follow-up period was 8 months. Overall, 141 residents aged ≥ 65 years from 10 aged person welfare facility were included. Dates when the body temperatures of participants were more than 37.2°C were recorded. Posterior teeth occlusion was evaluated by assessing functional tooth units (FTUs).

RESULTS

Data from 100 participants [median age, 89 (67-102)] were used for analysis. Total of 53 participants got a fever. The Kaplan-Meier analysis showed that the average period until onset of fever in participants with scores 0, 1-11 and 12 for FTU was 7.7 ± 0.6, 7.4 ± 1.0 and 3.9 ± 1.0, respectively. Cox's proportional hazards regression model revealed that participants with FTU = 0 were at higher risk of fever compared with those with FTU = 12 (hazards ratio: 3.2, 95% confidence interval: 1.4-7.7), adjusted for possible confounders.

CONCLUSIONS

Posterior teeth occlusion correlated with the risk of fever in older residents of nursing homes.

Trypsin-Like Activity in Oral Cavity Is Associated with Risk of Fever Onset in Older Residents of Nursing Homes: An 8-Month Longitudinal Prospective Cohort Pilot Study

This study aimed to evaluate the association between trypsin-like activity in the oral cavity and the onset of fever in independent older residents of nursing homes. Independent older residents aged ≥ 65 years in 10 nursing homes were included in this study, which was conducted in Kitakyushu, Japan. For 8 months, follow-up dates on which the body temperatures of participants were more than 37.2 °C were noted. Trypsin-like activity in the oral cavity was detected by ADCHECK® with five-grade evaluation at baseline. Data from 53 independent participants with median age 89.0 (67–102) years were available for analysis. ADCHECK® scores were associated with fever days (r = 0.312, p = 0.029). The average periods until the onset of fever in participants with ADCHECK® Scores 1 and 2, Score 3, and Scores 4 and 5 were 6.6 ± 0.5, 5.0 ± 0.7, and 4.1 ± 1.0 months, respectively. ADCHECK® Scores 4 and 5 signified a higher risk of fever compared to ADCHECK® Scores 1 and 2 (hazards ratio 5.9, 95% confidence interval 1.4–23.9, p = 0.013), adjusted for possible confounders. We concluded that trypsin-like activity in the oral cavity was associated with the risk of fever in independent older residents of nursing homes.

The situation of infection in the elderly in Spain: a multidisciplinary opinion document

Infection in the elderly is a huge issue whose treatment usually has partial and specific approaches. It is, moreover, one of the areas where intervention can have the most success in improving the quality of life of older patients. In an attempt to give the widest possible focus to this issue, the Health Sciences Foundation has convened experts from different areas to produce this position paper on Infection in the Elderly, so as to compare the opinions of expert doctors and nurses, pharmacists, journalists, representatives of elderly associations and concluding with the ethical aspects raised by the issue. The format is that of discussion of a series of pre-formulated questions that were discussed by all those present. We begin by discussing the concept of the elderly, the reasons for their predisposition to infection, the most frequent infections and their causes, and the workload and economic burden they place on society. We also considered whether we had the data to estimate the proportion of these infections that could be reduced by specific programmes, including vaccination programmes. In this context, the limited presence of this issue in the media, the position of scientific societies and patient associations on the issue and the ethical aspects raised by all this were discussed.

Cellulitis in older people over 75 years - are there differences?

Aim

To examine differences in risk factors, clinical features and outcomes of cellulitis between those 75 + years and those <75 years admitted to a metropolitan hospital.

Methods

A prospective study of patients with limb cellulitis requiring intravenous antibiotics conducted at Bankstown-Lidcombe Hospital, Australia from June 2014 to April 2015.

Results

Thirty one patients were 75 + years and 69 less than 75 years. A greater proportion of older patients resided in nursing home (25.8% vs 2.9% respectively, p = 0.001) and mobilized with walking aid(s) (58.1% vs 11.6% respectively, p < 0.001). Significantly more older patients had documented hypertension (45.2% vs 23.2% respectively p = 0.035), atrial fibrillation (33.5% vs 5.8% respectively, p < 0.001), dementia (22.6% vs 1.4% respectively, p = 0.001) and malignancy (16.1% vs 1.4% respectively, p = 0.010). The clinical presentation of cellulitis and cellulitis severity (Eron classification) did not significantly differ in both groups; however older patients were more likely to have dependent edema (OR 4.0, 95%CI 1.3-12.6, p = 0.018) and less likely to be obese (OR 0.3, 95%CI 0.1-0.8, p = 0.012) or had a past history of cellulitis (OR 0.3, 95%CI 0.1-1.0, p = 0.044) on presentation. Despite the age difference, there were no major differences in intravenous antibiotic choice, hospital length of stay, and hospital readmission rates in both groups. Older patients however, were more likely to experience complications such as falls and/or decreased mobility (38.7% vs 15.9% respectively, p = 0.020) during the cellulitis episode.

Conclusion

There are minor differences in the risk factors and clinical features of cellulitis in older patients as compared to the young. Outcomes are similar except for a higher incidence of hospital related complications.

Antibiotic Stewardship in Nursing Facilities

Misuse and overuse of antibiotic therapy is a frequent cause of resident harm in nursing facilities. As a result, newly released policy and regulatory initiatives will require antibiotic stewardship programs (ASPs) in nursing facilities. Although implementing ASPs can be challenging, improving the quality of antibiotic prescribing is achievable in this setting. The authors review the determinants of antibiotic prescribing in nursing facilities, strategies to improve antibiotic prescribing in this setting, current status of ASPs in nursing facilities, and steps that facilities can take to enhance existing ASP structure and process.

Does the CDC Definition of Fever Accurately Predict Inflammation and Infection in Persons With SCI?

Background: Pneumonia and septicemia have the greatest impact on reduced life expectancy in persons with spinal cord injury (SCI). Fever is often the first presenting symptom of infection or inflammation. Thermoregulatory dysfunction in persons with SCI may preclude a typical febrile response to infection or inflammation and thus delay diagnostic workup. Objective: To determine the core temperature of persons with SCI in the setting of infection or inflammation and the frequency with which it meets criteria for the CDC definition of fever (>100.4°F). Methods: Retrospective review of hospitalized SCI patients over 5 years with a diagnosis of infection or inflammation (DI), defined by serum leukocytosis. In this study, 458 persons with paraplegia (PP) and 483 persons with tetraplegia (TP) had 4,191 DI episodes. Aural temperatures (T_au) on the day of DI, 7 days prior, and 14 days afterwards were abstracted from medical records. Main outcome measures were average T_au at DI, frequency of temperatures >100.4°F at DI, and average baseline temperatures before and after DI. Results: Average T_au at DI was 98.2°F (±1.5) and 98.2°F (±1.4) in the TP and PP groups, respectively, with only 11.6% to 14% of DI resulting in T_au >100.4°F. Baseline temperatures ranged from 97.9°F (±0.7) to 98.0°F (±0.8). Conclusion: SCI persons with leukocytosis infrequently mount a fever as defined by the CDC, and baseline temperatures were subnormal (<98.6°F). Thermoregulatory dysfunction likely accounts for these findings. T_au >100.4°F is not a sensitive predictor of infection or inflammation in persons with SCI. Clinicians should be vigilant for alternative symptoms of infection and inflammation in these patients, so diagnostic workup is not delayed.

Emergency Presentations With Nonspecific Complaints-the Burden of Morbidity and the Spectrum of Underlying Disease: Nonspecific Complaints and Underlying Disease

The prevalence of diagnoses, morbidity, and mortality of patients with nonspecific complaints (NSC) presenting to the emergency department (ED) is unknown.To determine the prevalence of diagnoses, acute morbidity, and mortality of patients with NSC.Prospective observational study with a 30-day follow-up. Patients presenting to 2 EDs were enrolled by a study team and diagnosed according to the World Health Organization ICD-10 System.Of 217,699 presentations to the ED from May 2007 through to February 2011, a total of 1300 patients were enrolled. After exclusion of 90 patients who fulfilled exclusion criteria, 1210 patients were analyzed. No patient was lost to follow-up. In patients with NSC, the underlying diseases were spread throughout 18 chapters of the ICD-10. A total of 58.7% of the patients were diagnosed with acute morbidity. Thirty-day mortality was 6.4% overall. Patients with acute morbidity and suffering from heart failure and pneumonia had mortalities >15%; patients lacking acute morbidity, but suffering from functional impairment or depression/anxiety had mortalities of 0%. Although the history did not allow any prediction, age and sex were predictive of morbidity and mortality.The differential diagnoses in patients presenting with NSC is broad. Acute morbidity and mortality were high in the presented cohort, the predictors of morbidity and mortality being age and sex rather than the nature of the complaints. Urgently needed management strategies could be based on these results.ClinicalTrials.gov (#NCT00920491).

Drug fever after cancer chemotherapy is most commonly observed on posttreatment days 3 and 4

BACKGROUND

This study was undertaken to analyze the characteristics of fever after cancer chemotherapy in order to reduce unnecessary medical care.

METHODS

Retrospectively, 1016 consecutive cycles of cancer chemotherapy were analyzed. Fever was defined as a temperature of ≥ 37.5 °C lasting for 1 h. Age, sex, tumor histology, the treatment regimen, the timing of fever onset, the number of days for which the fever persisted, the cause of the fever, the presence or absence of radiotherapy, and the use of granulocyte colony-stimulating factor (G-CSF) were examined.

RESULTS

The patients included 748 males and 268 females (median age = 68, range = 29-88), of whom 949, 52, and 15 were suffering from lung cancer, malignant pleural mesothelioma, and other diseases, respectively. Fever was observed in 367 cycles (36 %), including 280 cycles (37 %) involving males and 87 cycles (32 %) involving females. Fever occurred most commonly in the first cycles and was higher than later cycles (41 vs. 30 %, p < 0.001). Fever occurred most frequently on posttreatment days 4 (8 %), 3 (7 %), and 12 (7 %), and the distribution of fever episodes exhibited two peaks on posttreatment days 3 and 4 and 10-14. Fever on posttreatment days 3 and 4 was most commonly observed in patients treated with gemcitabine (20 %) or docetaxel (18 %). The causes of fever included infection (47 %; including febrile neutropenia [24 %]), adverse drug effects (24 %), unknown causes (19 %), and tumors (7 %). Radiotherapy led to a significant increase in the frequency of fever (46 vs. 34 %, p < 0.001). Thirty-three percent of patients received G-CSF, and the incidence ratios of fever in patients who received G-CSF were higher than those who did not receive G-CSF (44 vs. 31 %, p < 0.001).

CONCLUSION

The febrile episodes that occurred on posttreatment days 3 and 4 were considered to represent adverse drug reactions after cancer chemotherapy. Physicians should be aware of this feature of chemotherapy-associated fever and avoid unnecessary examination and treatments including prescribing antibiotics.

Geriatric Fever Score: a new decision rule for geriatric care

BACKGROUND

Evaluating geriatric patients with fever is time-consuming and challenging. We investigated independent mortality predictors of geriatric patients with fever and developed a prediction rule for emergency care, critical care, and geriatric care physicians to classify patients into mortality risk and disposition groups.

MATERIALS AND METHODS

Consecutive geriatric patients (≥65 years old) visiting the emergency department (ED) of a university-affiliated medical center between June 1 and July 21, 2010, were enrolled when they met the criteria of fever: a tympanic temperature ≥37.2°C or a baseline temperature elevated ≥1.3°C. Thirty-day mortality was the primary endpoint. Internal validation with bootstrap re-sampling was done.

RESULTS

Three hundred thirty geriatric patients were enrolled. We found three independent mortality predictors: Leukocytosis (WBC >12,000 cells/mm3), Severe coma (GCS ≤ 8), and Thrombocytopenia (platelets <150 10(3)/mm3) (LST). After assigning weights to each predictor, we developed a Geriatric Fever Score that stratifies patients into two mortality-risk and disposition groups: low (4.0%) (95% CI: 2.3-6.9%): a general ward or treatment in the ED then discharge and high (30.3%) (95% CI: 17.4-47.3%): consider the intensive care unit. The area under the curve for the rule was 0.73.

CONCLUSIONS

We found that the Geriatric Fever Score is a simple and rapid rule for predicting 30-day mortality and classifying mortality risk and disposition in geriatric patients with fever, although external validation should be performed to confirm its usefulness in other clinical settings. It might help preserve medical resources for patients in greater need.

Shaking chills and high body temperature predict bacteremia especially among elderly patients

Purposes

The difference in predictors of bacteremia between elderly and non-elderly patients is unclear despite the aging of society. The objective was to determine predictors of bacteremia among elderly patients aged 80 years and older compared to non-elderly patients aged 18 to 79 years.

Methods

A referral hospital-based retrospective descriptive study from April 2012 to March 2013 in Okinawa, Japan. All enrolled patients were adults suspected of having bacterial infection who had been newly admitted into the Division of Infectious Diseases. HIV- infected patients were excluded. Exposures were a history of shaking chills, prior antibiotics use within 48 hours, vital signs, and laboratory inflammation markers on admission. Outcome was blood culture positivity.

Results

Three hundred and sixty-six patients were enrolled. Median age was 78.5 (interquartile range [IQR]: 62–88). Among patients aged 18 to 79 years, shaking chills (adjusted odds ratio [AOR] 2.22, 95% confidence interval [CI]: 1.09–4.51) and previous antibiotics use (AOR 0.08, 95% CI: 0.01–0.68) were significant. However, among patients aged 80 years and older, shaking chills (AOR 3.06, 95% CI: 1.30–7.19) and body temperature above 38.5°C (AOR 2.98, 95% CI: 1.30–6.83) were significant.

Conclusions

A history of shaking chills and vital signs indicating high body temperature were two findings that were useful in predicting bacteremia, especially in elderly patients aged 80 years and older. Further study is needed to assess whether the result is applicable in other regions and populations.

Brown versus white adipose tissue: a mini-review

BACKGROUND

Brown adipose tissue (BAT) is abundant in small mammals and in newborns and helps them to survive cold temperatures. In adults, it had long been considered to be absent or at least of no relevance. Recent investigations, however, have fuelled interest in adult BAT.

OBJECTIVE

We aimed at (1) summarizing structural and physiological characteristics of BAT versus white adipose tissue (WAT); (2) discussing the development of the two adipose tissue types; (3) reviewing the data available from human studies on BAT, and (4) discussing the impact of aging.

METHODS

We summarize recent descriptions of BAT and WAT based on the original literature and reviews in the field, with emphasis on human BAT.

RESULTS

WAT and BAT have essentially antagonistic functions: WAT stores excess energy as triglycerides and BAT is specialized in the dissipation of energy through the production of heat. Considerable amounts of BAT are present in a substantial proportion of adult humans and relatively high quantities of BAT are associated with lower body weight. With increasing age, BAT decreases and body weight increases.

CONCLUSIONS

Although the available cross-sectional data do not allow definite conclusions to be drawn concerning a causal relationship between loss of BAT and increasing body weight with advancing age or obesity-related metabolic disorders of older age, stimulation of BAT appears to be an attractive novel candidate target for the treatment of age-related obesity.

Caloric restriction retards the age-related decline in mitochondrial function of brown adipose tissue

Caloric restriction (CR) has been shown to prevent the age-associated loss of mitochondrial function and biogenesis in several tissues such as liver, heart, and skeletal muscle. However, little is known about the effects of CR on a tissue in which the mitochondria have no adenosine triphosphate (ATP)-producing purpose but show a high degree of uncoupling, namely brown adipose tissue (BAT). Hence, the aim of the present study was to analyze the effect of long-term CR on BAT mitochondrial function and biogenesis. BAT mitochondria obtained from 24-month-old male and female rats previously subjected to 40% CR for 12 months were compared with mitochondria from old (24 months) and young (6 months) ad libitum fed rats. Old restricted rats compared to old ad libitum fed ones showed a reduction in BAT size with respect to fat content and adipocyte number. Mitochondrial DNA content in BAT increased with age and even more so in restricted rats, indicating a summative effect of age and CR on mitochondrial proliferation. CR induced resistance to lose total and mitochondrial protein, COX activity, and uncoupling capacity with advancing age, in relation with a lower decrease of mitochondrial transcription factor A (TFAM). In summary, our results demonstrate CR prevents the age-associated decline in mitochondrial function in BAT, probably in relation with a lower impairment of mitochondrial biogenesis.

Is the concentration of C-reactive protein in bacteraemia associated with age?

BACKGROUND

C-reactive protein (CRP) is an indicator of inflammation, and is often used in the diagnosis of bacterial infections. It is poorly known whether CRP in bacterial infection is age-dependent.

METHODS

Adult patients with a positive blood culture with E. coli or S. pneumoniae during 1994-2004 were included. CRP measured on the same date as the blood cultures were drawn (CRP1), 2-3 days (CRP2) and 4-7 days later (CRP3), were retrieved. The patients were divided into three age groups, < 65, 65-84, and > or = 85, respectively. We studied three cut-off values for CRP and produced age-specific receiver operating characteristics (ROC) curves, using patients with acute coronary or cerebral infarction as controls.

RESULTS

890 patients and 421 controls were available. There was a statistically significant negative correlation between age and CRP1 - 0.072 (p = 0.032). The median CRP1 and CRP2 were significantly higher in the youngest age group. The area under the ROC-curve for the youngest age group was significantly greater than that of the two other age groups, but we found no statistically significant differences in sensitivity related to age. The diagnostic sensitivity of CRP was better for S. pneumoniae than for E. coli, 92.6% vs. 88.0% (p = 0.046) for a cut-off value of 40 mg/L, and 82.4% vs. 61.5% (p =< 0.01) for a cut-off value of 120 mg/L.

CONCLUSION

CRP is better in identifying infection with S. pneumoniae than with E. coli. We found a weakening of the CRP-response with age, but this is hardly of clinical significance.

Dietary restriction modifies fever response in aging rats

Intermittent (every-other-day) feeding initiated at 19 months of age and continued for 12 weeks, led to a moderate decrease in body weight of aging rats, enhanced survival and modified diurnal changes in body temperature and fever response to bacterial endotoxin (E. coli lipopolysaccharide, LPS). Diet-restricted animals which survived LPS administration, displayed reduced febrile response, i.e. (i) a moderate hypothermia in an early phase, and (ii) a delayed onset of body temperature elevation, as compared with their ad libitum-fed controls. However, peak body temperature values were similar in both groups. The rats of both groups which did not develop hyperthermia in response to LPS, died within 24 h of LPS administration. In control, but not in diet-restricted rats, variations in body weight during the 12 weeks prior LPS administration may be predictable in regard to their survival after LPS treatment. It seems that the resistance to bacterial endotoxin in aging rats is associated with their ability to develop hyperthermia.

Predictors of outcome in geriatric patients with urinary tract infections

A study was conducted to determine the prognosis of geriatric patients with urinary tract infections (UTIs) and identify clinical factors associated with adverse outcomes. This retrospective, cohort study identified elderly patients (age > or =65 years) presenting to an academic, urban Emergency Department (ED) during a 16-week period with UTI, suggested by urinalysis and pertinent symptoms. There were 37 demographic and clinical variables analyzed as potential predictors of outcome. Morbidity was defined as in-hospital death, Intensive Care Unit (ICU) admission, hospital length of stay (LOS) >2 days, or hospital intravenous (i.v.) antibiotics >2 days. Factors identified by univariate analysis were combined using multiple logistic regression to identify independent predictors of morbidity. There were 284 patients who met selection criteria. Thirteen patients (4.6%) died during hospitalization and 27 (9.5%) had ICU admission, 139 (48.9%) had LOS >2 days, and 75 (26.4%) had i.v. antibiotics >2 days. Multivariate analysis identified the following variables as independent predictors of adverse outcomes: mental status change, frequent UTIs, other nonurinary infections, abnormal temperature, tachycardia, hypotension, elevated BUN, hyperglycemia, elevated WBC, and relative neutrophilia. Regression models for adverse outcomes had sensitivities from 74.8% to 96.2% and specificities from 31.1% to 69.0%. In conclusion, this study defines high rates of morbidity for geriatric patients with UTIs and describes predictive variables that may help identify low-risk patients. These data may lay the foundation for determining specific guidelines for disposition of this high-risk patient population.

The impact of ADL status, dementia and body mass index on normal body temperature in elderly nursing home residents

A subset of seniors might demonstrate a lower body temperature compared with younger subjects. However, data on normal body temperature in seniors are sparse. The aim of the study was to study normal body temperature with a view of predicting factors of low body temperature in non-febrile seniors. Elderly women (n=159) and 78 men, aged > or =65 years, living in community resident homes were included in the study. Data on chronic diseases and medication were collected from medical records. Tympanic and rectal temperature was measured twice daily; once at 7-9 AM and then at 6-8 PM. In addition, body mass index (BMI), activities of daily living (ADL) status, as well as details regarding dementia and malnutrition were recorded. The variation in tympanic and rectal temperatures ranged from 33.8 to 38.4 degrees C and 35.6 to 38.0 degrees C, respectively. ADL status, dementia and BMI were significantly related to lower and analgesic to higher tympanic temperature. Dementia was significantly related to lower rectal temperature. Therefore, dementia, BMI, ADL status and analgesic shall not be overlooked when assessing temperature in seniors. More research is needed to further clarify the influence of these predictive factors, as well as the impact of BMI and malnutrition.

Fever in the elderly

Infections in the elderly, similar to other acute illnesses in this age group, may present in atypical, nonclassical fashions. Fever, the cardinal sign of infection, may be absent or blunted 20%-30% of the time. An absent or blunted fever response may in turn contribute to diagnostic delays in this population, which is already at risk for increased morbidity and mortality due to infection. On the other hand, the presence of a fever in the geriatric patient is more likely to be associated with a serious viral or bacterial infection than is fever in a younger patient. Finally, a diagnosis can be made in the majority of cases of fever of unknown origin (FUO) in the elderly. FUO is often associated with treatable conditions in this age group.

Evaluation of the elderly patient with weakness: an evidence based approach

Because of the altered physiology of the elderly population, either as a result of aging or as a result of other disease processes, many illnesses may present with features that are either atypical or nonspecific in nature. Difficult and nonspecific complaints such as weakness in an elderly patient must be handled in a judicious, cost-effective, comprehensive, and expeditious manner that benefits both the patient and the emergency department. This article addresses the evaluation of the elderly patient who presents to the ED complaining of weakness.

Interleukin-1beta-induced fever in young and old Long-Evans rats

Aging is associated with a blunted or absent fever response to naturally occurring infections or to the peripheral administration of bacterial products and proinflammatory cytokines, including interleukin-1beta (IL-1beta). Whether old rats also exhibit an attenuated fever response when challenged with direct brain administration of IL-1beta is unknown. Here we investigated the fever response of young (3-5 mo) and old (24-26 mo) Long-Evans rats to the intracerebroventricular microinfusion of IL-1beta. Core body temperature was monitored by telemetry in freely moving rats. Intracerebroventricularly administered IL-1beta induced comparable increases in body temperature in young and old Long-Evans rats. In the two groups, IL-1beta-induced fever was similar both in latency to peak fever and maximal fever response, whether the cytokine was administered 2 h after lights on or just before lights off. These data show that old Long-Evans rats are not defective in their capacity to develop a fever in response to brain administration of IL-1beta.

Brain eicosanoids and LPS fever: species and age differences

The results of the present study, summarized in Table 2, demonstrate that different species and strains of rodents (rats and mice) and birds (chickens) exhibit rather specific fever response. Systemic administration of LPS caused monophasic elevation in Tb of chickens, biphasic changes in Tb of rats (initial drop followed by an increase in Tb), whereas mice failed to develop hyperthermia and responded by a decreased Tb. The LPS-induced alterations in hypothalamic prostanoid synthesis were also rather species-specific and differ markedly even between the two strains of mice. We failed to find a common direct correlation between LPS-induced changes in Tb and hypothalamic prostanoid production in rodents (rats and mice). This observation is supported by our recent study on age-related changes in fever response in rats, where we found that hypothalami of LPS-treated old and young adult rats produced similar amounts of PGE2 and PGI2, in spite of more pronounced and prolonged hypothermia, and a delayed elevation in Tb of old rats, as compared with young (Fraifeld et al., 1995b). Moreover, the hypothalamus of febrile chickens did not display any detectable activation of PGE2 production, suggesting that PGE2 is not a common central mediator of fever in homeotherms (Fraifeld et al., 1995a). Apparently, the actual body temperature not always reflects the functional state of central thermostat, and increased PGE2 production in hypothalamus would not directly, at least in rodents, lead to body temperature elevation. Furthermore, peripheral effects, including PG-mediated ones, of pyrogens can interfere and even overcome their centrally-mediated effects (Morimoto et al., 1991; Burysek et al., 1993). Previously, we have shown that no additional elevation in hypothalamic PGE2 production occurs in response to doses of LPS over 10 micrograms in rats and 25 micrograms in mice, while the increased doses led to further changes in Tb response (Kaplanski et al., 1993). Morimoto et al. (1991) have considered that PGE2 acts centrally to cause fever and peripherally to cause hypothermia, and, hence, these opposing actions, both being induced by LPS, may act together to determine the final thermoregulatory response. Other possibilities could be related to counterbalance of endogenous antipyretics (Kluger, 1991; Kozak et al., 1995), that may occur not only at the level of thermoregulatory center but also outside the CNS (Klir et al., 1995), and to the existence of PG-independent mechanisms of LPS fever. The latter have been shown for IL-8 (Rothwell et al., 1990; Zampronio et al., 1994) and MIP-1 (Davatelis et al., 1989; Minano et al., 1990; Hayashi et al., 1995; Lopez-Valpuesta and Myers, 1995), which are, apparently, mediated via CRF (Strijbos et al., 1992; Zampronio et al., 1994), and INF-alpha, mediated via the opioid receptor mechanisms (Hori et al., 1991, 1992). However, it has been shown recently that in different species the same pyrogenic cytokines (IL-8) may induced fever via different, PG-independent (in rats; Zampronio et al., 1994) or PG-dependent (in rabbits; Zampronio et al., 1995) mechanisms. It should be noted that fever response is not always accompanied by an elevation in Tb. The final effect of pyrogens on body temperature depends upon the balance between heat production and heat loss, which in turn is highly dependent upon body size and ambient temperature, especially in small animals. Perhaps, the hypothermic response observed in our mice and rats at 22 degrees C may be in part attributed to ambient temperature, which was below a thermoneutral zone. The reduced febrile response is considered, at least in part, to contribute to an increased mortality and prolonged recovery from infections (Kluger, 1986). From this point, it is difficult to suggest whether the hypothermia observed in our mice and rats could be of somewhat adaptive significance. It has been shown that at the ambient temperature of 30 degrees C, Swiss Webster mice can re

Fever in the elderly

Fever in elderly persons is only one clinical presentation that can be used to assist the clinician at suspecting a serious disease, such as an infection. Infections, like all other illnesses in the geriatric patient, may occur with a variety of nonspecific, atypical, nonclassic, and unusual manifestations. The clinician caring for elderly patients should be aware of these nonclassical presentations of infections in this age group. Unexplained change in functional capacity, worsening of mental status, weight loss or failure to thrive, weakness and fatigue, falls, and generalized pain are only some of the clues that may aid the clinician in considering infection in elderly persons. Key concepts of fever in older adults are: Fever generally indicates presence of serious infection, most often caused by bacteria. Fever may be absent in 20%-30% of elderly patients harboring a serious infection. Criteria for fever in elderly patients should also include an elevation of body temperature of at least 2 degrees F from baseline values. FUO in elderly persons is caused by infections (30%-35%), CTD (25%-30%), and malignancies (15%-20%) in the majority of cases.

Effect of different ambient temperature and lipopolysaccharide administration on the circadian rhythm of rectal temperature and hypothalamic PGE2 production in aged male rats

Old and young male rats (22 and 7 months respectively) were exposed to ambient temperatures of 4, 22, 27 and 35 degrees C. The rats' rectal temperatures (RTs) were measured periodically, after exposure to the varying temperatures at different hours during the day. The mean circadian value of RTs in the aged rats was different from that of the young rats. Whereas exposure to low temperatures caused a decrease of 2.0 degrees C in the RTs of the old rats, exposure to heat (35 degrees C) caused an increase of 1 degree C in their RTs. An injection of 200 micrograms (intraperitoneally) of E. coli lipopolysaccharide caused them to experience a long period of hypothermia. Elevation in the RTs after the hypothermic period ended was significantly lower in the old rats. However no significant differences in hypothalamic PGE2 production were to be found between the old and young groups 24 h after pyrogen administration.

Epidemiologic aspects of infective endocarditis in an urban population. A 5-year prospective study

A prospective study of the epidemiology of infective endocarditis (IE) in a well-defined urban population of 428,000 inhabitants during a 5-year period was carried out. All patients were treated in the same institution, and history, diagnostic procedures, and treatment were standardized. Of 233 consecutive suspected episodes of IE, 127 fulfilled the modified von Reyn criteria. After patients not living in the defined area were excluded, 99 episodes in 90 patients were analyzed in the epidemiologic part of the study. Of these, 33 episodes were definite endocarditis, verified by surgery or autopsy; 35 probable; and 31 possible endocarditis episodes. Another 34 episodes were found retrospectively and are included in the incidence calculation. The crude incidence was calculated to be 6.2/100,000 inhabitants per year, which is high compared to earlier studies. Adjusted to the population of Sweden, the incidence was 5.9/100,000 inhabitants per year. The annual incidence was higher for women, 6.6/100,000, than for men, 5.8/100,000. In the oldest age-group (80-89 years) the annual incidence was 22/100,000 in the prospective study and 30/100,000 if retrospective cases were included. Contrary to almost all other studies, we did not find a male predominance among our cases. Only 7% of patients were intravenous drug abusers, and 15% had a prosthetic valve. The most common bacteria were methicillin-susceptible Staphylococcus aureus (31%) and alpha-streptococci (28%); 12% of episodes were culture negative. The mortality from IE in the population was 1.4/100,000 inhabitants per year. A higher-than-expected incidence of IE was found, especially among older patients and women.

Delayed febrile response in old rats is not associated with an inability of hypothalamus to produce prostaglandin E2

E. coli lipopolysaccharide (100 micrograms per rat, i.p.) induced a twofold increase in hypothalamic prostaglandin E2 (PGE2) production both in young adult (8 months) and old (28-30 months) male Wistar rats. It seems that the ability of the hypothalamus to produce PGE2 in response to bacterial endotoxin is not affected with aging, and hence delayed febrile response observed in old rats is not related to hypothalamic PGE2 production.

Necrotizing fasciitis: the role of Staphylococcus epidermidis, immune status and intravascular coagulation

An 83 year old Caucasian woman with necrotizing fasciitis (NF) of the right hand is described. Staphylococcus epidermidis was the only organism cultured. Serology failed to demonstrate Streptococcus pyogenes, the common pathogen of NF. Despite antibiotic therapy, gangrene supervened, necessitating digital amputation. Staphylococcus epidermidis is usually non-pathogenic, but review of the literature indicates that it is relatively commonly found with other pathogens in NF. Accordingly, studies of immune status were undertaken. Apart from reduced myeloperoxidase production (30-50% of normal levels), all humoral, cell-mediated and neutrophil function tests were normal. This is the first report of Staphylococcus epidermidis as the sole isolate in NF and also the only study of immune status of NF patients. It is concluded that a non-virulent organism (e.g. Staphylococcus epidermidis) may be pathogenic in the face of advanced age alone. Elevated fibrin degradation productions were also demonstrated in the patient, consistent with lysis of localized intravascular thrombus. The role of anticoagulation in NF is discussed.

Systemic dissemination as a result of oral infection in individuals 50 years of age and older

The oral pathosis caused by systemic disorders in middle-aged and elderly adults has been the focus of many publications in recent years. The intraoral soft and hard tissue changes associated with systemic disorders, medications, chemotherapy, and radiation treatment have been well-investigated and -documented. Far less attention has been paid to the role of oral infection as the etiology of systemic disorders. A literature review (1980-1994) is provided here focusing on well-documented cases in which systemic disorders were caused by oral foci of infections. This paper attempts to raise the level of awareness of practitioners in considering possible systemic complications caused by oral infection. It also emphasizes the need for further longitudinal studies in this field involving healthy and medically compromised elderly individuals.

Patient assessment. Infection in the elderly

1. Along with a decrease in immune competence, older adults are found to have reduced sensitivity of several homeostatic mechanisms that will also predispose them to the development of infection. 2. Common infections in the elderly include pneumonia, tuberculosis, urinary tract infections, and skin infections. 3. Nursing can play a pivotal role in the prevention of infection in the older adult by providing information on the importance of influenza and pneumococcal vaccines, instituting early risk assessment identification, and developing proactive nursing interventions for those individuals at risk.

The effects of aging on the function of alveolar macrophages in mice

In order to determine whether the function of alveolar macrophages (AM) is modulated by aging, we measured the TNF-alpha production, phagocytic function, and surface antigen expression of AM from young and old mice. When AM were primed by IFN-gamma (500 units/ml) and triggered by LPS (100 micrograms/ml), TNF-alpha production by AM was significantly smaller in old mice as compared with young mice (young mice: 161.7 +/- 28.2 units/ml; old mice: 89.3 +/- 13.6 units/ml, P < 0.05). The percentage of AM which phagocytosed latex particles (more than one particle) in old mice was significantly lower than in young mice (young: 78.1 +/- 2.5%; old: 62.8 +/- 3.4%, P < 0.05). Ia antigen expression of the AM was significantly higher and asialo-GM1 antigen expression was significantly lower in old mice than in young mice (Ia: young, 0.030 +/- 0.005; old, 0.092 +/- 0.024, P < 0.05; asialo-GM1: young, 0.-9 +/- 0.01; old, 0.75 +/- 0.07, P < 0.01). These results suggest that alveolar macrophage function is at least decreased in part with aging in mice.

Infections in the elderly

Weakness, falls, incontinence or altered mental states may signal infection in the elderly, while fever may be absent. Bacteria are the most likely cause, and the most common sites are the respiratory system, the urinary tract and the soft tissues. Joint infections and meningitis must be remembered, as must bacterial endocarditis. Herpes zoster may be ameliorated by early treatment with acyclovir. Annual influenza vaccination is recommended, and amantadine may protect against influenza A (not B) during outbreaks. A single pneumococcal vaccination is recommended for those with chronic cardiopulmonary disease or alcoholism or for those who are immunosuppressed. All major hospitals and large nursing homes have committees which can give advice on infection control.

Antibiotics for nursing home residents. When are they appropriate?

Antibiotics are used often in nursing homes in response to high rates of infection. Physicians and nursing home administrators and staff need to work in concert to avoid inappropriate prescription of antibiotics in this setting. Physicians need to know how infection presents in frail, institutionalized elderly patients; strive to prevent infection; and prescribe antibiotics only in situations in which clear benefit has been demonstrated. Nursing home administrators and staff must institute comprehensive infection control programs, adopt specific guidelines for antibiotic use, and keep physicians informed about the number and types of infections and antibiotic susceptibility patterns.

Infection and immune response in the elderly

A number of immunologic functions have been shown to decline in an age-related fashion, particularly cell-mediated immunity and antibody response to an immunogen. Underlying degenerative diseases and medications further contribute to the immunologic abnormalities noted in the elderly. The elderly in hospitals and nursing homes are a particularly vulnerable subset, with a high incidence of institutionally acquired infection. Aspects of disease prevention in the elderly are discussed.

Difficulty in predicting bacteremia in elderly emergency patients

STUDY OBJECTIVES

To characterize the clinical presentation and identify factors predictive of bacteremia in elderly patients.

DESIGN

Retrospective review of emergency department charts, hospital records, and microbiology reports.

SETTING

Community teaching hospital with annual ED census of 65,000 adults.

PARTICIPANTS

Seven hundred fifty elderly patients (aged 65 to 99 years) who were evaluated by the emergency physician, had blood cultures obtained in the ED, and were hospitalized with a suspected infectious process during a 12-month period.

MEASUREMENTS

Records were analyzed for demographic information, underlying diseases, clinical presentation, laboratory findings, sources of infection, and causative organisms. Using contingency tables, 79 patients with positive blood cultures were compared with a random sample of 136 patients with sterile blood cultures to identify clinical variables significantly (P less than .05) associated with bacteremia. Logistic regression analysis was performed with significant factors to develop a model to predict bacteremia. Sensitivity, specificity, and predictive values were calculated for the model.

MAIN RESULTS

The prevalence of bacteremia was 10.6%. Escherichia coli was the most commonly isolated pathogen (29% of cases), and the urinary tract was the most common source of infection (44.3% of cases). Logistic regression analysis showed that altered mental status (odds ratio, 2.88; 95% confidence interval [Cl], 1.52 to 5.50), vomiting (odds ratio, 2.63; 95% Cl, 1.16 to 6.15), and WBC band forms of more than 6% (0.06) (odds ratio, 3.50; 95% Cl, 1.58 to 5.27) were independent predictors of bacteremia. The presence of at least one of these three factors had a sensitivity of 0.85 (95% Cl, 0.75 to 0.92) and a specificity of 0.46 (95% Cl, 0.38 to 0.55) for predicting bacteremia in the study group. The positive predictive value was 0.16 (95% Cl, 0.12 to 0.19) and the negative predictive value was 0.96 (95% Cl, 0.94 to 0.98) for the ED patient group that met inclusion criteria.

CONCLUSION

Elderly patients fail to manifest identifiable clinical features indicative of bloodstream infection. The sensitivity and specificity of the best statistical model for identifying bacteremic elderly patients suggest that clinical indicators alone are unreliable predictors of bacteremia in the geriatric ED population studied.

Increased susceptibility of aged rats to haemorrhage and intravascular hypercoagulation following endotoxin administered in a generalized Shwartzman regime

Ageing rats are known to have an increased incidence of myocardial fibrosis and dyspnoea caused by pulmonary intravascular coagulation. In order to determine whether endotoxin can be responsible for such responses in ageing rats we have exposed rats of differing ages (2 months, 16 months and 24 months) to single or repeated (two doses 24 h apart; generalized Shwartzman regime) intravenous doses of endotoxin (E. coli 0111 B4). Only the 2-year-old rats reacted adversely. Two doses of endotoxin produced death, with focal myocardial necrosis, haemorrhage and pulmonary and hepatic intravascular coagulation. The increased susceptibility of aged rats to the toxic effects of endotoxin explains some of the changes found in the tissues of old rats. The sporadic nature of both cardiac failure and dyspnoea as a cause of morbidity and mortality in ageing rats may be related to the need for two endotoxin episodes in a period of 24 h to provoke a generalized Shwartzman reaction, an occurrence likely to be relatively uncommon under natural conditions.

Fever response in elderly nursing home residents: are the older truly colder?

OBJECTIVE

To test the hypothesis that many nursing home residents with an apparently blunted fever response (maximum temperature less than 101 degrees F) may actually have a significant change in temperature (delta T greater than or equal to 2.4 degrees F) which is not recognized because of a low baseline temperature.

DESIGN

Retrospective chart review for cases of infection that met specific criteria and for chart-recorded baseline and infection temperatures. Chart-recorded baseline temperatures were prospectively compared with re-measurement of morning temperatures.

SETTING

Nursing Home Care Unit of the VAMC West Los Angeles.

PATIENTS

Random review of 40 residents' charts resulted in the detection of 69 infections among 26 residents over a 20-month period. Fifty randomly selected residents prospectively underwent comparison of chart-determined and actual re-measurement of baseline temperatures.

RESULTS

In 50 randomly selected residents, the mean oral baseline temperature of 97.4 +/- 0.2 (degrees F +/- SEM) closely approximated the mean nurse-recorded measures in the charts (97.6 +/- 0.1). Chart review detected 69 infections among 26 residents, with 53 episodes having a temperature recorded during the infection. The mean maximum temperature (Tmax) during an infection was 101.3 +/- 0.3 (degrees F +/- SEM) but 47% (25/53) of the episodes had a "blunted" fever response (Tmax less than 101 degrees F). Of the 25 "blunted" fevers (Tmax less than 101 degrees F), about one-fourth demonstrated an adequate change in temperature from baseline (delta T greater than or equal to 2.4 degrees F) but failed to reach 101 degrees F because of a low baseline. Most infections (89%) had a Tmax greater than 99 degrees F.

CONCLUSION

Establishing a nursing home patient's basal temperature and monitoring for changes in temperature (delta T greater than 2.4 degrees F) and/or lowering the threshold for recognition of fevers (to 99 degrees or 100 degrees F) in nursing home residents with a change in function should assist in early recognition of infections.

The behavior of sick animals

Dogs and cats that are ill with febrile diseases usually are depressed and anorexic. When viewed from the standpoint of the wild ancestors, it is apparent that the behavior of sick animals is adaptive and not necessarily a reflection of debilitation. A wild animal that is acutely ill with an infectious disease often is at a life-or-death juncture, and its behavioral mode may be seen as putting the animal's resources into facilitating the fever response in combating the pathogens.

Comparative endotoxin-induced hepatic injury in young and aged rats

Recent studies have demonstrated that aged rats are more susceptible to the lethal effects of endotoxin (ET) than young rats. The early (15 min to 7 h) hepatic ultrastructural and biochemical changes induced by ET in young (6 months) and aged (24 months) rats were evaluated to elucidate cell populations and/or the mechanisms that may be responsible for the previously observed differential effects. Aged rats given ET had significantly increased numbers of neutrophils in hepatic sinusoids at 30 min and thereafter as compared with ET-treated young rats. Morphologic evidence of coagulation within hepatic sinusoids, including aggregates of fibrin enmeshed among polymorphonuclear leukocytes and platelet aggregates, was frequently observed in ET-treated aged rats but not in ET-treated young rats. In contrast, Kupffer cells of ET-treated young rats frequently contained phagocytized neutrophils and platelets, whereas this phenomenon was rarely observed in Kupffer cells of ET-treated aged rats. Hepatocellular morphologic injury was more pronounced and occurred at earlier time periods in ET-treated aged rats, and was accompanied by significant increase in hepatic transaminases. ET-treated aged rats had an earlier onset and greater severity of endothelial cell injury than did ET-treated young rats. The results of this study indicate a greater aggregation of blood elements in the hepatic sinusoids of aged rats following the intravenous administration of ET, which suggests that a greater diminution in microcirculation was induced in aged rats by ET. Additionally, the increased phagocytosis of inflammatory cells by Kupffer cells of young rats may be a mechanism which affords protection against endotoxin-induced lethality.