The impact of hospital-acquired bloodstream infections

Costs associated with hospital-acquired bacteraemia in a Belgian hospital

Studies from around the world have shown that hospital-acquired infections increase the costs of medical care due to prolongation of hospital stay, and increased morbidity and mortality. The aim of this study was to determine the extra costs associated with hospital-acquired bacteraemias in a Belgian hospital in 2001 using administrative databases and, in particular, coded discharge data. The incidence was 6.6 per 10000 patient days. Patients with a hospital-acquired bacteraemia experienced a significantly longer stay (average 21.1 days, P<0.001), a significantly higher mortality (average 32.2%, P<0.01), and cost significantly more (average 12853 euro, P<0.001) than similar patients without bacteraemia. At present, the Belgian healthcare system covers most extra costs; however, in the future, these outcomes of hospital-acquired bacteraemia will not be funded and prevention will be a major concern for hospital management.

Purpura Fulminans Due toStaphylococcus aureus

BACKGROUND

Purpura fulminans is an acute illness commonly associated with meningococcemia or invasive streptococcal disease, and it is typically characterized by disseminated intravascular coagulation (DIC) and purpuric skin lesions. In this article, we report the first 5 cases (to our knowledge) of purpura fulminans directly associated with Staphylococcus aureus strains that produce high levels of the superantigens toxic shock syndrome toxin-1 (TSST-1), staphylococcal enterotoxin serotype B (SEB), or staphylococcal enterotoxin serotype C (SEC).

METHODS

Cases were identified in the Minneapolis-St. Paul, Minnesota, metropolitan area during 2000-2004. S. aureus infection was diagnosed on the basis of culture results, and susceptibility to methicillin was determined. The ability of the isolated organisms to produce TSST-1, SEB, SEC, and Panton-Valentine leukocidin (PVL) was determined. TSST-1, SEB, and SEC levels were also quantified after in vitro growth of the organisms.

RESULTS

In 3 of the 5 cases, the infecting S. aureus strain was isolated from the blood cultures. In 2 of the 5 cases, the infecting S. aureus strain was isolated only from the respiratory tract, indicating that purpura fulminans and toxic shock syndrome resulted from exotoxin and/or other host factors, rather than septicemia. One of these latter 2 patients also had necrotizing pneumonia, and the isolated S. aureus was a methicillin-resistant strain that produced both SEC and PVL. Only 2 of the 5 patients survived, and 1 of the survivors received activated protein C.

CONCLUSIONS

Staphylococcal purpura fulminans may be a newly emerging illness associated with superantigen production. Medical practitioners should be aware of this illness.

Age and caloric restriction diets are confounding factors that modify the response to lipopolysaccharide by peritoneal macrophages in C57BL/6 mice

Aging is the result of several detrimental changes that lead to a decrease in homeostasis, an increase in the incidence of degenerative diseases, and death. A caloric-restricted diet (CR), which consists of a significant reduction in calorie intake (40%) without malnutrition, has been shown to delay the onset of age-related diseases and pathologies and to extend life span. The aims of this study were to assess the effects of aging and CR on lipopolysaccharide (LPS)-dependant cytokine production by peritoneal macrophages (PMphis). Resident naïve PMphis were isolated from 2- to 24-month-old male C57BL/6 mice and were stimulated with Escherichia coli LPS (100 ng/mL) for 1 to 5 h in culture conditions. A linear decrease in the production of LPS-induced tumor necrosis factor alpha (TNF-alpha) and interleukin (IL) 10 was observed with age. LPS-induced IL-6 and IL-1beta levels were also reduced with age, but in a nonlinear fashion. Expression of CD14, the major receptor for LPS, on the PMphi surface was also observed to decline with age. Moreover, TNF-alpha production by PMphis was reduced in mice undergoing the two different CR diets of limited daily feeding and intermittent fasting, as compared with ad libitum-fed mice. The results of this study add the new variables age and diet to the paradigm proposing that the response to LPS is modulated by multiple components, including genetic background and sex.

Antibiotic Lock Technique: A Review of the Literature

OBJECTIVE:

To review the literature on the use of the antibiotic lock technique (ALT) as a treatment option for patients with highly needed catheters.

DATA SOURCES:

MEDLINE and International Pharmaceutical Abstracts were searched (1980–August 2004). Search terms included antibiotic lock, catheter infection, and topical treatment.

STUDY SELECTION AND DATA EXTRACTION:

Articles describing use of ALT in the treatment of catheter infections in humans and studies evaluating in vitro stability of antibiotics were included.

DATA SYNTHESIS:

ALT has been used in patients with highly needed catheters, usually for parenteral nutrition, cancer chemotherapy, or dialysis. Catheters are considered highly needed when removal is not feasible or desirable due to lack of alternative injection sites for required therapy. Success rates in saving the infected catheter have been variable and may depend on the infecting organism. In addition, there are conflicting data in terms of compatibility of antibiotics with heparin solutions.

CONCLUSIONS:

Consensus appears to be that the ALT can be tried for patients with highly needed catheters when infection with coagulase-negative staphylococci is documented and no systemic signs of sepsis, such as hypotension, are evident. Most of these patients are likely to need systemic therapy as well. Infection of the catheter associated with systemic gram-negative bacteremia or fungemia will most likely require removal of the catheter to prevent systemic complications. Additional research with the ALT is warranted given unanswered questions.

Epidemiology and antifungal susceptibility of Candida species isolated from blood: results of a 2-year multicentre study in Spain

This study, included in the prospective survey of candidaemia in Europe supported by the European Confederation of Medical Mycology, presents the epidemiological and antifungal susceptibility results of 290 cases of candidaemia (80 in children <15 years old) reported from September 1997 to August 1999 by 19 Spanish hospitals. Presence of an intravenous catheter and previous antibiotic therapy were the most frequent risk factors. The percentages of the four most common species isolated (adults/children) were as follows: Candida albicans (46/36.2), C. parapsilosis (21.9/50), C. tropicalis (12.8/3.75), and C. glabrata (10.1/5). As initial therapy, fluconazole was preferred in adults (54%) and liposomal amphotericin B in children (58%). The 30-day mortality rate was 40.6%, and the species most frequently associated with a fatal outcome was C. krusei (60%). The rates of susceptibility to antifungal agents were as follows: amphotericin B, 91%; flucytosine, 99%; fluconazole, 93.6%; itraconazole, 87.4%; and voriconazole, 92%. These results provide baseline data for future epidemiological and susceptibility studies and for evaluating the impact of new antifungal agents on the distribution of species and the mortality rates associated with candidaemia in Spain.

Computer algorithms to detect bloodstream infections

We compared manual and computer-assisted bloodstream infection surveillance for adult inpatients at two hospitals. We identified hospital-acquired, primary, central-venous catheter (CVC)-associated bloodstream infections by using five methods: retrospective, manual record review by investigators; prospective, manual review by infection control professionals; positive blood culture plus manual CVC determination; computer algorithms; and computer algorithms and manual CVC determination. We calculated sensitivity, specificity, predictive values, plus the kappa statistic (kappa) between investigator review and other methods, and we correlated infection rates for seven units. The kappa value was 0.37 for infection control review, 0.48 for positive blood culture plus manual CVC determination, 0.49 for computer algorithm, and 0.73 for computer algorithm plus manual CVC determination. Unit-specific infection rates, per 1,000 patient days, were 1.0-12.5 by investigator review and 1.4-10.2 by computer algorithm (correlation r = 0.91, p = 0.004). Automated bloodstream infection surveillance with electronic data is an accurate alternative to surveillance with manually collected data.

Ecological theory suggests that antimicrobial cycling will not reduce antimicrobial resistance in hospitals

Hospital-acquired infections caused by antibiotic-resistant bacteria pose a grave and growing threat to public health. Antimicrobial cycling, in which two or more antibiotic classes are alternated on a time scale of months to years, seems to be a leading candidate in the search for treatment strategies that can slow the evolution and spread of antibiotic resistance in hospitals. We develop a mathematical model of antimicrobial cycling in a hospital setting and use this model to explore the efficacy of cycling programs. We find that cycling is unlikely to reduce either the evolution or the spread of antibiotic resistance. Alternative drug-use strategies such as mixing, in which each treated patient receives one of several drug classes used simultaneously in the hospital, are predicted to be more effective. A simple ecological explanation underlies these results. Heterogeneous antibiotic use slows the spread of resistance. However, at the scale relevant to bacterial populations, mixing imposes greater heterogeneity than does cycling. As a consequence, cycling is unlikely to be effective and may even hinder resistance control. These results may explain the limited success reported thus far from clinical trials of antimicrobial cycling.

Accuracy and appropriateness of antimicrobial susceptibility test reporting for bacteria isolated from blood cultures

Accurate antimicrobial susceptibility testing (AST) and appropriate reporting of AST results for pathogens isolated from blood cultures are critical functions of the microbiology laboratory. We studied AST performance and reporting from positive blood cultures at hospital microbiology laboratories in Iowa. One hundred sixteen episodes of bacteremia from 14 participating hospitals were examined. We detected AST or identification errors for 18 episodes (16%) and judged reporting of AST results to be inappropriate for 38 episodes (33%). Further study is necessary to determine the impact of testing errors and suboptimal reporting of results on the management of bloodstream infection.

Evidence-based practice: examining the risk of toys in the microenvironment of infants in the neonatal intensive care unit

Toys placed in the bed or microenvironment of infants in the neonatal intensive care unit (NICU) demonstrate high rates of colonization (92%). As with other fomites, toys may be one potential source of nosocomial infection (NI). This project critically evaluated the practice of placing toys in the microenvironment of critically ill infants by using the Iowa Model of Evidence-Based Practice to Promote Quality Care. With the model as a guide for decision making, the existing evidence was explored using a systematic review of the literature, case studies, scientific principles, theory, and expert opinion. A comprehensive review of the literature did not clearly identify a causal relationship between toys in the NICU microenvironment and NI. Levels of evidence suggesting an association between toys and NI were determined to be moderately strong and consistent. A plausible relationship between the practice of placing toys in the beds of NICU patients and risk for infection was found. These findings prompted a pilot practice change, eliminating toys in the NICU, to test the potential impact of this intervention. Pre- and postintervention infection rates were compared. NI rates decreased from 4.6 to 1.99 per 1,000 patient days over a 6-month evaluation period. Although this decrease was not statistically significant, it was the lowest rate recorded in 5 years. Ongoing evaluation of NI rates is in progress. Individual NICUs must determine if the evidence warrants a practice change in their setting.

Prevalence and antimicrobial susceptibilities of bacteria isolated from blood cultures of hospitalized patients in the United States in 2002

BACKGROUND

Bloodstream infections are associated with significant patient morbidity and mortality. Antimicrobial susceptibility patterns should guide the choice of empiric antimicrobial regimens for patients with bacteremia.

METHODS

From January to December of 2002, 82,569 bacterial blood culture isolates were reported to The Surveillance Network (TSN) Database-USA by 268 laboratories. Susceptibility to relevant antibiotic compounds was analyzed using National Committee for Clinical Laboratory Standards guidelines.

RESULTS

Coagulase-negative staphylococci (42.0%), Staphylococcus aureus (16.5%), Enterococcus faecalis (8.3%), Escherichia coli (7.2%), Klebsiella pneumoniae (3.6%), and Enterococcus faecium (3.5%) were the most frequently isolated bacteria from blood cultures, collectively accounting for >80% of isolates. In vitro susceptibility to expanded-spectrum beta-lactams such as ceftriaxone were high for oxacillin-susceptible coagulase-negative staphylococci (98.7%), oxacillin-susceptible S. aureus (99.8%), E. coli (97.3%), K. pneumoniae (93.3%), and Streptococcus pneumoniae (97.2%). Susceptibilities to fluoroquinolones were variable for K. pneumoniae (90.3-91.4%), E. coli (86.0-86.7%), oxacillin-susceptible S. aureus (84.0-89.4%), oxacillin-susceptible coagulase-negative staphylococci (72.7-82.7%), E. faecalis (52.1%), and E. faecium (11.3%). Combinations of antimicrobials are often prescribed as empiric therapy for bacteremia. Susceptibilities of all blood culture isolates to one or both agents in combinations of ceftriaxone, ceftazdime, cefepime, piperacillin-tazobactam or ciprofloxacin plus gentamicin were consistent (range, 74.8-76.3%) but lower than similar beta-lactam or ciprofloxacin combinations with vancomycin (range, 93.5-96.6%).

CONCLUSION

Ongoing surveillance for antimicrobial susceptibility remains essential, and will enhance efforts to identify resistance and attempt to limit its spread.

A prospective epidemiological survey of candidaemia in Sweden

A prospective epidemiological survey of candidaemia was performed in central Sweden from January 1998 to December 1999. In total, 191 episodes were reported with an overall rate of 0.32/1000 admissions. Candida albicans was identified in 128 cases (67%), followed by Candida glabrata in 30 (15.7%) and Candida parapsilosis in 14 (7.3%). Predisposing factors included surgery (31.4%), intensive care (18.8%), solid tumour or haematological malignancy (15.7%), and foetal immaturity (15.7%). Non-albicans Candida species were more prevalent among patients with haematological malignancies (56%), compared to surgical (30%) and ICU patients (19%). The crude mortality rate of candidaemia was 31%. The highest mortality rate was observed in patients with haematological malignancies (41.2%), age > 70 y (41%), surgery (38.5%) and infections with > 1 Candida species (40%) or C. glabrata (38%).

Frequency of Gram-negative bacterial pathogens in bloodstream infections and their resistance to antibiotics in the Czech Republic

A study performed at 12 hospitals in the Czech Republic in 2001 evaluated the Gram-negative bacterial pathogens most frequently associated with bloodstream infections and their susceptibility to a selection of antimicrobial agents. Of 831 Gram-negative strains, the most frequently isolated organisms were Escherichia coli (32%), Klebsiella pneumoniae (24%) and Pseudomonas aeruginosa (10%). E. coli isolates were relatively susceptible to the antibiotics tested, whereas K. pneumoniae were relatively resistant to all agents except meropenem, and P. aeruginosa to all agents except gentamicin and amikacin. Other agents showed variable rates of resistance to penicillins, third-generation cephalosporins, aminoglycosides and ciprofloxacin.

Low caloric intake is associated with nosocomial bloodstream infections in patients in the medical intensive care unit

OBJECTIVE

To determine whether caloric intake is associated with risk of nosocomial bloodstream infection in critically ill medical patients.

DESIGN

Prospective cohort study.

SETTING

Urban, academic medical intensive care unit.

PATIENTS

Patients were 138 adult patients who did not take food by mouth for > or =96 hrs after medical intensive care unit admission.

MEASUREMENTS

Daily caloric intake was recorded for each patient. Participants subsequently were grouped into one of four categories of caloric intake: <25%, 25-49%, 50-74%, and > or =75% of average daily recommended calories based on the American College of Chest Physicians guidelines. Simplified Acute Physiology Score II and serum albumin were measured on medical intensive care unit admission. Serum glucose (average value and maximum value each day) and route of feeding (enteral, parenteral, or both) were collected daily. Nosocomial bloodstream infections were identified by infection control surveillance methods.

MAIN RESULTS

The overall mean (+/-sd) daily caloric intake for all study participants was 49.4 +/- 29.3% of American College of Chest Physicians guidelines. Nosocomial bloodstream infection occurred in 31 (22.4%) participants. Bivariate Cox analysis revealed that receiving > or =25% of recommended calories compared with <25% was associated with significantly lower risk of bloodstream infection (relative hazard, 0.24; 95% confidence interval, 0.10-0.60). Simplified Acute Physiology Score II also was associated with risk of nosocomial bloodstream infection (relative hazard, 1.27; 95% confidence interval, 1.01-1.60). Average daily serum glucose, admission serum albumin, time to initiating nutritional support, and route of nutrition did not affect risk of bloodstream infection. After adjustment for Simplified Acute Physiology Score II in a multivariable analysis, receiving > or =25% of recommended calories was associated with a significantly lower risk of bloodstream infection (relative hazard, 0.27; 95% confidence interval, 0.11-0.68).

CONCLUSIONS

In the context of reducing risk of nosocomial bloodstream infections, failing to provide > or =25% of the recommended calories may be harmful. Higher caloric goals may be necessary to achieve other clinically important outcomes.

Epidemiology of candidaemia in Europe: results of 28-month European Confederation of Medical Mycology (ECMM) hospital-based surveillance study

In order to update the epidemiological and mycological profile of candidaemia in Europe, the European Confederation of Medical Mycology conducted a prospective, sequential, hospital population-based study from September 1997 to December 1999. A total of 2,089 cases were documented by 106 institutions in seven European countries. Rates of candidaemia ranging from 0.20 to 0.38 per 1,000 admissions were reported. Candida albicans was identified in 56% of cases. Non-albicans Candida species were most frequently isolated from patients with haematological malignancies (65%). With increasing age, an increasing incidence of Candida glabrata was seen. The 30-day mortality rate was 37.9%. The survey results underline the burden of candidaemia in a wide range of patient populations, confirm the importance of non- albicans species, and provide baseline data for future surveillance studies at a European level.

In vitro susceptibilities of gram-negative bacteria isolated from hospitalized patients in four European countries, Canada, and the United States in 2000-2001 to expanded-spectrum cephalosporins and comparator antimicrobials: implications for therapy

Access to current antimicrobial agent surveillance data is an important prerequisite for the optimal management of patients with hospital-acquired infections. The present study used data collected in 2000 to 2001 from 670 laboratories in Europe (France, Germany, Italy, and Spain), Canada, and the United States to report on the in vitro activities of ceftriaxone, cefotaxime, and comparative agents against >125,000 isolates of gram-negative bacteria from hospitalized patients. All but two isolates of Enterobacteriaceae (one isolate of Proteus mirabilis from France and one isolate of Morganella morganii from Canada) were susceptible to imipenem. The susceptibility of Escherichia coli to ceftriaxone or cefotaxime was > or = 97% in each country, and for P. mirabilis, susceptibility was 99% in each country except Italy. In contrast, susceptibility of E. coli to ciprofloxacin varied from 80.5% (Spain) to 94.0% (France); levofloxacin susceptibility ranged from 75.2% (Spain) to 91.6% (United States). Among Klebsiella pneumoniae and Klebsiella oxytoca isolates, ceftriaxone and cefotaxime susceptibilities ranged from 86.6 to 98.7% and 83.5 to 99.7%, respectively, depending upon the country. Considerable geographic variation in the susceptibilities (generally 85 to 95% susceptible) of Serratia marcescens and M. morganii to ceftriaxone and cefotaxime were observed. For S. marcescens, susceptibility to piperacillin-tazobactam varied from 81.5% (France) to 94.1% (Italy) and susceptibility to ciprofloxacin ranged from 66.2% (Germany) to 90.7% (Spain). Enterobacter cloacae and Enterobacter aerogenes were less susceptible to ceftriaxone and cefotaxime than were the other species of Enterobacteriaceae studied. The present study demonstrated that established parenteral expanded-spectrum cephalosporin antimicrobial agents retain significant in vitro activity against many clinically important gram-negative pathogens.

Antibiotic resistance

Through billions of years of evolution, microbes have developed myriad defense mechanisms designed to ensure their survival. This protection is readily transferred to their fellow life forms via transposable elements. Despite very early warnings, humans have chosen to abuse the gift of antibiotics and have created a situation where all microorganisms are resistant to some antibiotics and some microorganisms are resistant to all antibiotics. When antibiotics are used, six events may occur with only one being beneficial: when the antibiotic aids the host defenses to gain control and eliminate the infection. Alternatively, the antibiotic may cause toxicity or allergy, initiate a superinfection with resistant bacteria, promote microbial chromosomal mutations to resistance, encourage resistance gene transfer to susceptible species, or promote the expression of dormant resistance genes.

Antibiotic-impregnated catheters associated with significant decrease in nosocomial and multidrug-resistant bacteremias in critically ill patients

OBJECTIVE

To evaluate the impact of using central venous catheters (CVCs) impregnated with the combination of minocycline and rifampin on nosocomial bloodstream infections (BSIs), morbidity, and mortality in cancer patients in the ICU.

DESIGN

Prospective surveillance study consisting of the following two time periods: September 1997 through August 1998 (ie, fiscal year [FY] 1998); and from September 1998 through August 1999 (ie, FY 1999).

SETTING

ICUs of a tertiary care hospital in Houston, TX.

PATIENTS

Cancer patients in the medical ICU (MICU) and surgical ICU (SICU).

INTERVENTIONS

ICUs started using CVCs impregnated with the minocycline-rifampin combination at the beginning of FY 1999.

MEASUREMENTS AND MAIN RESULTS

The rates of nosocomial BSIs and other patients' characteristics were compared for the two study periods to determine the impact of using the impregnated catheters in the ICU. Patients' characteristics, including antibiotic use, were comparable for the two study periods in both the MICU and the SICU. The rate of nosocomial BSIs in the MICU unit decreased from 8.3 to 3.5 per 1,000 patient-days (p < 0.01), and decreased in the SICU from 4.8 to 1.3 per 1,000 patient-days (p < 0.01) in FY 1999. Nosocomial vancomycin-resistant enterococcus (VRE) bacteremia also decreased significantly (p = 0.004). Length of stay in the MICU and SICU significantly decreased in FY 1999 (p < 0.01 and p = 0.03, respectively). The duration of hospitalization decreased for MICU and SICU patients (p = 0.06 and p < 0.01, respectively). The rate of catheter-related infections decreased from 3.1 to 0.7 per 1,000 patient-days in FY 1999 (p = 0.02). The decrease in infections resulted in net savings of at least $1,450,000 for FY 1999.

CONCLUSIONS

The use of antibiotic-impregnated CVCs in the MICU and SICU was associated with a significant decrease in nosocomial BSIs, including VRE bacteremia, catheter-related infections, and lengths of hospital and ICU stays.

Real-time monitoring of bacterial infection in vivo: development of bioluminescent staphylococcal foreign-body and deep-thigh-wound mouse infection models

Staphylococcal infections associated with catheter and prosthetic implants are difficult to eradicate and often lead to chronic infections. Development of novel antibacterial therapies requires simple, reliable, and relevant models for infection. Using bioluminescent Staphylococcus aureus, we have adapted the existing foreign-body and deep-wound mouse models of staphylococcal infection to allow real-time monitoring of the bacterial colonization of catheters or tissues. This approach also enables kinetic measurements of bacterial growth and clearance in each infected animal. Persistence of infection was observed throughout the course of the study until termination of the experiment at day 16 in a deep-wound model and day 21 in the foreign-body model, providing sufficient time to test the effects of antibacterial compounds. The usefulness of both animal models was assessed by using linezolid as a test compound and comparing bioluminescent measurements to bacterial counts. In the foreign-body model, a three-dose antibiotic regimen (2, 5, and 24 h after infection) resulted in a decrease in both luminescence and bacterial counts recovered from the implant compared to those of the mock-treated infected mice. In addition, linezolid treatment prevented the formation of subcutaneous abscesses, although it did not completely resolve the infection. In the thigh model, the same treatment regimen resulted in complete resolution of the luminescent signal, which correlated with clearance of the bacteria from the thighs.

Epidemiology and outcome of nosocomial and community-onset bloodstream infection

We performed a prospective study of bloodstream infection to determine factors independently associated with mortality. Between February 1999 and July 2000, 929 consecutive episodes of bloodstream infection at two tertiary care centers were studied. An ICD-9-based Charlson Index was used to adjust for underlying illness. Crude mortality was 24% (14% for community-onset versus 34% for nosocomial bloodstream infections). Mortality attributed to the bloodstream infection was 17% overall (10% for community-onset versus 23% for nosocomial bloodstream infections). Multivariate logistic regression revealed the independent associations with in-hospital mortality to be as follows: nosocomial acquisition (odds ratio [OR] 2.6, P < 0.0001), hypotension (OR 2.6, P < 0.0001), absence of a febrile response (P = 0.003), tachypnea (OR 1.9, P = 0.001), leukopenia or leukocytosis (total white blood cell count of <4500 or >20000, P = 0.003), presence of a central venous catheter (OR 2.0, P = 0.0002), and presence of anaerobic organism (OR 2.5, P = 0.04). Even after adjustments were made for underlying illness and length of stay, nosocomial status of bloodstream infection was strongly associated with increased total hospital charges (P < 0.0001). Although accounting for about half of all bloodstream infections, nosocomial bloodstream infections account for most of the mortality and costs associated with bloodstream infection.

The combination of polymicrobial sepsis and endotoxin results in an inflammatory process that could not be predicted from the independent insults

BACKGROUND

The variable clinical profile observed in critically ill patients is the result of multiple factors. Genetic determinants have recently been shown as confounding factors in the response to injury. However, other elements, such as the environment and the type of injury, could modify this response. The objective of this investigation was to study the effect of combining insults and different genetic backgrounds on the inflammatory response.

MATERIALS

Male mice, C57BL/6J (B6) and A/J, were randomized to undergo cecal ligation and single puncture (CLP) or sham operation (SOP). After 24 h of recovery, mice were randomized again into two groups, one group was injected with bacterial lipopolysaccharide (LPS; 15 mg/kg) and the other was injected with normal saline (NS). An additional experimental group included mice that were not operated (NOP) and injected with LPS. Mice were evaluated by plasma cytokine content.

RESULTS

The combination of insults resulted in an apparent additive effect for some cytokines, such as interleukin (IL) 6. In contrast, tumor necrosis factor alpha (TNF-alpha) was considerably lower in the combined injury group with respect to injection of LPS alone. There was no relevant difference in IL-10 levels between any group, except that its decay was slower in the CLP + LPS group. Overall, cytokine levels were different between B6 and A/J mice indicating a genetic contribution.

CONCLUSIONS

These results indicate that the response to stress is the combination of the type of injury and the genetic background of the subject. These observations also illustrate the difficulty in predicting the inflammatory response and underlying mechanism based on cytokine plasma levels.

The epidemiology of sepsis in the United States from 1979 through 2000

BACKGROUND

Sepsis represents a substantial health care burden, and there is limited epidemiologic information about the demography of sepsis or about the temporal changes in its incidence and outcome. We investigated the epidemiology of sepsis in the United States, with specific examination of race and sex, causative organisms, the disposition of patients, and the incidence and outcome.

METHODS

We analyzed the occurrence of sepsis from 1979 through 2000 using a nationally representative sample of all nonfederal acute care hospitals in the United States. Data on new cases were obtained from hospital discharge records coded according to the International Classification of Diseases, Ninth Revision, Clinical Modification.

RESULTS

Review of discharge data on approximately 750 million hospitalizations in the United States over the 22-year period identified 10,319,418 cases of sepsis. Sepsis was more common among men than among women (mean annual relative risk, 1.28 [95 percent confidence interval, 1.24 to 1.32]) and among nonwhite persons than among white persons (mean annual relative risk, 1.90 [95 percent confidence interval, 1.81 to 2.00]). Between 1979 and 2000, there was an annualized increase in the incidence of sepsis of 8.7 percent, from about 164,000 cases (82.7 per 100,000 population) to nearly 660,000 cases (240.4 per 100,000 population). The rate of sepsis due to fungal organisms increased by 207 percent, with gram-positive bacteria becoming the predominant pathogens after 1987. The total in-hospital mortality rate fell from 27.8 percent during the period from 1979 through 1984 to 17.9 percent during the period from 1995 through 2000, yet the total number of deaths continued to increase. Mortality was highest among black men. Organ failure contributed cumulatively to mortality, with temporal improvements in survival among patients with fewer than three failing organs. The average length of the hospital stay decreased, and the rate of discharge to nonacute care medical facilities increased.

CONCLUSIONS

The incidence of sepsis and the number of sepsis-related deaths are increasing, although the overall mortality rate among patients with sepsis is declining. There are also disparities among races and between men and women in the incidence of sepsis. Gram-positive bacteria and fungal organisms are increasingly common causes of sepsis.

[Two first years' bacteremia incidence and impact in a new hospital]

BACKGROUND AND OBJECTIVE

We pursued here to determine the incidence of blood-stream infections.

PATIENTS AND METHOD

Longitudinal descriptive study. All patients admitted to hospital from January 1999 to December 2000 were included. Blood-stream infection episodes were defined according to CDC criteria. Blood-stream infection prevalence and incidence density (ID), nosocomial primary blood-stream infection attributable to intravascular devices intravascular devices and population attributable fraction were estimated.

RESULTS

Overall blood-stream infection ID was 1.3 por 1,000 patient-years. Nosocomial blood-stream infection represented 1.1 per 1,000 patient-days. Nosocomial primary blood-stream infection attributable risk was 54.3%, population attributable risk was 49.8% and population attributable fraction was 86.6%.

CONCLUSIONS

The incidence of blood-stream infection was similar to that reported by other centers. The impact of intravascular devices on nosocomial blood-stream infections in our hospital was high

Device-related sources of bacteraemia in English hospitals--opportunities for the prevention of hospital-acquired bacteraemia

Between 1997 and 2001, 17 teaching and 56 non-teaching acute English hospitals conducted hospital-wide surveillance of hospital-acquired bacteraemia (HAB) using a standard protocol drawn up by the Nosocomial Infection National Surveillance Scheme (NINSS). The sources of organisms, the incidence of device-related HAB, and the distribution of HABs from individual device-related sources by specialty and type of hospital were determined for 6,956 HABs in order to identify where resources should best be targeted to reduce these infections. The overall incidence of HAB was higher in teaching than in non-teaching hospitals: 5.39 and 2.83 HABs per 1,000 patients at risk, respectively (P<0.001). Device-related sources were responsible for 52.4 and 43.2% of all HABs in teaching and non-teaching hospitals, respectively (P<0.001), and central lines were the commonest source, causing 38.3% of HABs in teaching versus 22.3% in non-teaching hospitals (P<0.001). In teaching hospitals, general intensive care units (ICUs), haematology, special care baby units (SCBUs), nephrology, and oncology accounted for only 6.1% of the population surveyed, but had the highest incidence of HAB, and contributed 47.8% of 2091 HABs and 56.9% of 1,095 device-related bacteraemias. Of 623 device-related bacteraemias in these high-risk specialties, 554 (88.9%) were from central lines. Thus, in teaching hospitals, resources should be targeted primarily at the prevention of central line-related bacteraemia in these five high-risk specialties, and the surveillance should include data on central line use. In non-teaching hospitals, nearly two thirds (63.3%) of 4,865 HABs and 60.7% of 2,103 device-related bacteraemias were from a few specialties with a low incidence of bacteraemia, but large numbers of patients, namely general medicine, general surgery, geriatric medicine and urology. These specialties accounted for 50.5% of the population surveyed. Central lines were the most common source of bacteraemia in general medicine and surgery, and together accounted for 23.3% of all device-related bacteraemias. However, in geriatric medicine and urology, central line sources were infrequent, accounting for only 1.7% of all device-related bacteraemias. On the other hand, bacteraemia from catheter-associated UTI were common in all these four specialties accounting for 20.9% of all device-related bacteraemias. Thus, in non-teaching hospitals, resources should be targeted primarily at these low-risk specialties and surveillance should include, at least, bacteraemia from central lines and from catheter-associated UTI. Further benefit can be obtained by including central line-related bacteraemias from general ICU and haematology patients, as they contributed 17.0% of all device-related bacteraemias in non-teaching hospitals.

Use of simulated blood cultures for time to detection comparison between BacT/ALERT and BACTEC 9240 blood culture systems

In order to avoid the influence of pre-analytical steps, the following study was performed by using sterile blood spiked with defined loads of microorganisms as inoculum. Time-to-Detection (TTD) was evaluated for the most frequently encountered bacteria and fungi in septicemia, comparing two commercially available blood culture systems, BACTEC 9240 (Becton Dickinson) and BacT/ALERT (Organon Teknika). A specific medium, Bactec Mycosis IC/F (Becton Dickinson), was compared with the Bactec Plus Aerobic (Becton Dickinson) and FAN Aerobic (Organon Teknika) media for recovery of fungi in general and in case of mixed bacterial/fungal septicemia. The results show that the BACTEC system detects nearly all enrolled microorganisms significantly faster than the BacT/ALERT; the anaerobic vial contributes to the detection of anaerobes and facultative anaerobes and, in the case of BACTEC, shortens TTD; the Bactec Mycosis IC/F bottle shortens TTD of fungi.

A decade of antimicrobial susceptibilities at the University of Kentucky Hospital

OBJECTIVE

To determine the antimicrobial susceptibility rates for key antimicrobial agents and selective bacterial pathogens in the decade of the 1990s.

METHODS

Data from 1990 to 2000 from the University of Kentucky Clinical Microbiology Laboratory were analyzed by linear regression analysis to identify agents and pathogens that show a decline in susceptibility. For selected pathogens and antimicrobial agents, predictions were made for further declines in susceptibility for 2005 and 2010.

RESULTS

Significant declines in susceptibility to selected antimicrobial agents were found for Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pneumoniae. Further declines were predicted for 2005 and 2010.

CONCLUSIONS

Examination of susceptibility rates over time in a university hospital medical center provides useful data for future planning. In our institution, antimicrobial susceptibility rates have significantly declined during the 1990s for certain antimicrobial agents and bacterial pathogens. We are attempting to change our antimicrobial use patterns through formulary manipulation and clinician education, which may retard or prevent such declines in the future.

Multidrug resistance in bacterial isolates from blood cultures of haematology patients

The bacteria most frequently isolated from blood cultures of haematology patients in Warsaw were staphylococci (58.0%), Enterobacteriaceae (18.6%), non-fermenting rods (6.9%), enterococci (4.3%) and anaerobes (4.3%). Coagulase-negative staphylococci were the most common species isolated (92.7%) with 83.2% of these strains resistant to methicillin. Among enteric bacteria, 17.3% strains produced extended-spectrum-beta-lactamases. All eight isolates of enterococci showed high level resistance to aminoglycosides.

Antibiotic-resistant enterococci: the mechanisms and dynamics of drug introduction and resistance

Enterococci possess a vast array of mechanisms to resist the lethal effects of most antimicrobial drugs currently approved for therapeutic use in humans, thus presenting a considerable therapeutic challenge. This review summarizes current concepts regarding the mechanisms of resistance, as well as the emergence, proliferation, and epidemiology of resistant enterococci.