Unusual cause of lethal pulmonary aspergillosis in patients with chronic obstructive pulmonary disease

Two patients admitted to two different medical wards of our institution following respiratory decompensation of chronic obstructive pulmonary disease (COPD) were subsequently transferred to the same room of the medical intensive care unit (ICU) and intubated. Both patients developed invasive pulmonary aspergillosis and died soon after. Because COPD itself is rarely associated with lethal pulmonary aspergillosis, both cases were reviewed, and a retrospective investigation was conducted. Both patients had repeated sputum cultures while on the medical ward before their admission to the ICU; none of the sample grew Aspergillus spp. A. fumigatus was found in tracheal aspirates of both patients from the first day of their intubation while in the ICU. The pulmonary condition of both patients worsened, and invasive aspergillosis was diagnosed by bronchoalveolar lavage. Despite therapy with amphotericin B, the patients died 16 and 22 d after intubation, respectively. Both deaths were attributed to pulmonary aspergillosis; autopsy confirmed a massive pneumonia of the five lobes due to A. fumigatus in one patient. Investigation revealed that an air filter had been replaced 30 h before the first patient was admitted to the room. Experimental air filter replacement performed 12 d after the second patient died revealed the presence of A. fumigatus on the surface of the filters as well as a 10-fold increase in room air fungal counts during the procedure. This study shows that exposure to high concentrations of airborne Aspergillus spp. related to air filter change was associated with fatal invasive aspergillosis in two mechanically ventilated patients. Such infection can be prevented by the establishment and application of guidelines for air filter replacement.

Predicting survival of patients with sepsis by use of regression and neural network models

OBJECTIVES

(1) To predict at the time of diagnosis of sepsis the subsequent occurrence of multiple organ failure and patient death; and (2) to compare the prediction accuracies of standard multiple logistic regression (MLR) and neural network (NN) models.

METHODS

The data were collected during a 5-year period for all patients (n=173) who met prospectively determined criteria for sepsis and had positive blood culture results while admitted in the surgical intensive care unit at the University Hospital of Geneva, Switzerland. These data formed the basis for a retrospective cohort study described elsewhere. The MLR model was adapted from existing data. An NN model of the feed-forward, back-propagation type was constructed for predicting the outcome of sepsis with bloodstream infection. Both models were constructed from randomly chosen subsets of patients and subsequently were evaluated on the remaining (independent) patients.

RESULTS

Survival after sepsis was predicted with an accuracy of 80% by the NN model, which used only information collected at the time of the diagnosis of sepsis. The development of multiple organ failure after the diagnosis of sepsis was predicted accurately (81.5%) with either the MLR or the NN model. Both the MLR and the NN methods depended on the interpretation of a likelihood quantity, requiring the choice of a threshold to make a survival prediction. The accuracy of the MLR models was very sensitive to the threshold value. The accuracy of the NN models was not sensitive to the choice of threshold, because they generated likelihood predictions that were distributed far from the middle range where the threshold was placed.

CONCLUSION

Compared with MLR models, the NN models were slightly more accurate and much less sensitive to the arbitrary threshold parameter.

Bedside prediction of mortality from bacteremic sepsis. A dynamic analysis of ICU patients

The prognosis in patients with sepsis depends on severity of acute illness, underlying chronic diseases, and complications associated with infection. Adjusting for these factors is essential for evaluation of new therapies. The purpose of the present study was to determine variables readily identifiable at the bedside that predict mortality in intensive care unit (ICU) patients with sepsis and positive blood cultures. For a 5-yr period, all patients of a surgical ICU presenting with positive blood cultures and sepsis were systematically analyzed for clinical variables and organ dysfunctions at the day of onset of sepsis and bacteremia and during the subsequent clinical course. The prognostic value of these variables was determined using logistic regression procedures. Of the 5,457 admissions to the ICU, 176 patients developed sepsis with positive blood cultures (3.2 per 100 admissions). The fatality rate was 35% at 28 days after the onset of sepsis; in-hospital mortality was 43%. Independent predictors of mortality at onset of sepsis were previous antibiotic therapy (odds ratio [OR], 2.40; 95% confidence interval [CI95], 1.59 to 3.62; p = 0.034), hypothermia (OR, 1.43; CI95, 1.04 to 2.44; p = 0.030), requirement for mechanical ventilation (OR, 2.97; CI95, 1.96 to 4.51; p = 0.009), and onset-of-sepsis APACHE II score (OR, 1.21; CI95, 1.13 to 1.29; p < 0.001). Vital organ dysfunctions developing after the onset of sepsis influenced outcome markedly. The best two independent prognostic factors were the APACHE II score at the onset of sepsis (OR, 1.13 per unit; CI95, 1.08 to 1.17; p = 0.0016) and the number of organ dysfunctions developing thereafter (OR, 2.39; CI95, 2.02 to 2.82; p < 0.001). In ICU patients with sepsis and positive blood cultures, outcome can be predicted by the severity of illness at onset of sepsis and the number of vital organ dysfunctions developing subsequently. These variables are easily assessed at the bedside and should be included in the evaluation of new therapeutic strategies.

Intravascular device-related infections in critically ill patients

Intravascular device-related infections (IVDRIs) are among the most common nosocomial infections in critically ill patients. Quantitative or semi-quantitative microbiology diagnosis is necessary for their management. Most causative organisms arise from the skin; staphylococci are responsible for two-thirds of the IVDRIs, with Staphylococcus aureus responsible for 5% to 15%. Complications may include septic shock, suppurative thrombophlebitis, and endocarditis. In critically ill patients, intravenous lines are responsible for at least 23% of nosocomial bloodstream infection, which has a mortality of 25% and is associated with a longer stay in intensive care and costs $28,960 per survivor. IVDRIs can be treated with intravenous antibiotics without removing the device, but removal of the catheter is recommended. Prevention is based on careful insertion practice and optimal catheter care. Systemic replacement of the intravenous lines every three to five days is common practice in the USA but not elsewhere in Europe. This issue should be studied, particularly in critically ill patients.

Nosocomial bloodstream infections. Secular trends in rates, mortality, and contribution to total hospital deaths

BACKGROUND

Nosocomial bloodstream infections occur at a rate of 1.3 to 14.5 per 1000 hospital admissions and are believed to lead directly to 62,500 deaths per year in the United States. Measures of the incidence and the proportion of all hospital deaths related to deaths from these infections provide estimates of their impact. The objectives of the study were to characterize the secular trends in nosocomial bloodstream infection at a single institution and to estimate the population-attributable risk for death among patients experiencing the infection.

METHODS

A 12-year retrospective study using prospectively collected data from a hospital-wide surveillance system for nosocomial infections in a 900-bed tertiary care institution. All patients (N = 260,834) admitted to the institution between 1980 and 1992 were included in the study. Bloodstream infection rates were calculated for the 10 leading groups of pathogens, and trends were analyzed using simple linear regression. In-hospital mortality rates from patients who did or did not develop nosocomial blood stream infections were compared.

RESULTS

Between 1980 and 1992, a total of 3077 patients developed 3464 episodes of nosocomial bloodstream infection. The crude infection rates increased linearly from 6.7 to 18.4 per 1000 discharges (0.83 to 1.72 episodes per 1000 patient-days) during the 12-year study period (r = .87). Increases in the infection rates were due to gram-positive cocci (r = .96) and yeasts (r = .95) and essentially explained by infections caused by coagulase-negative staphylococci, Staphylococcus aureus, enterococci, and Candida species, respectively. Although the crude mortality in patients with nosocomial bloodstream infections decreased from 51% in 1981 to 29% in 1992, the in-hospital population-attributable mortality among infected patients increased from 3.55 deaths per 1000 discharges in 1981 to 6.22 per 1000 discharges in 1992 (r = .67). The etiologic fraction or the proportion of deaths in patients with bloodstream infection to all deaths occurring in the hospital increased from 11.4% in 1981 to 20.4% in 1992 (r = .59).

CONCLUSIONS

The incidence, the etiologic fraction, and the population-attributable risk for death among patients experiencing nosocomial bloodstream infections increased progressively during the last decade.

[Candida infections in intensive care]

The incidence of Candida spp is increasing in critically ill patients. The impact of the infection is briefly reviewed. Infections mainly evolve from endogenous colonization facilitated by the use of broad spectrum antibiotics; nosocomial exogenous transmission occasionally occurs, however. A complete understanding of the process of infection requires careful epidemiological investigation as well as the use of powerful laboratory tools that allow intraspecies delineation of Candida strains. The value of contour-clamped homogeneous field gel electrophoresis is discussed. Preventive treatments with antifungal agents will help to improve the outcome of severe infection, but still need to be evaluated in appropriately controlled clinical trials.

Systemic inflammatory response syndrome, sepsis, severe sepsis and septic shock: incidence, morbidities and outcomes in surgical ICU patients

OBJECTIVES

To determine the incidence of systemic inflammatory response syndrome (SIRS), sepsis and severe sepsis in surgical ICU patients and define patient characteristics associated with their acquisition and outcome.

DESIGN

One-month prospective study of critically ill patients with a 28 day in-hospital follow up.

SETTING

Surgical intensive care unit (SICU) at a tertiary care institution.

METHODS

All patients (n = 170) admitted to the SICU between April 1 and April 30, 1992 were prospectively followed for 28 days. Daily surveillance was performed by two dedicated, specifically-trained research nurses. Medical and nursing chart reviews were performed, and follow up information at six and twelve months was obtained.

RESULTS

The in-hospital surveillance represented 2246 patient-days, including 658 ICU patient-days. Overall, 158 patients (93%) had SIRS for an incidence of 542 episodes/1000 patients-days. The incidence of SIRS in the ICU was even higher (840 episodes/1000 patients-days). A total of 83 patients (49%) had sepsis; among them 28 developed severe sepsis. Importantly, 13 patients had severe sepsis after discharge from the ICU. Patient groups were comparable with respect to age, sex ratio, and type of surgery performed. Apache II score on admission to the ICU and ASA score at time of surgery were significantly higher (p < 0.05) only for patients who subsequently developed severe sepsis. The crude mortality at 28 days was 8.2% (14/170); it markedly differed among patient groups: 6% for those with SIRS vs. 35% for patients with severe sepsis. Patients with sepsis and severe sepsis had a longer mean length of ICU stay (2.1 +/- 0.2 and 7.5 +/- 1.5, respectively) than those with SIRS (1.45 +/- 0.1) or control patients (1.16 +/- 0.1). Total length of hospital stay also markedly differed among groups (35 +/- 9 (severe sepsis), 24 +/- 2 (sepsis), 11 +/- 0.8 (SIRS), and 9 +/- 0.1 (controls, respectively).

CONCLUSIONS

Almost everyone in the SICU had SIRS. Therefore, because of its poor specificity, SIRS was not helpful predicting severe sepsis and septic shock. Patients who developed sepsis or severe sepsis had higher crude mortality and length of stay than those who did not. Studies designed to identify those who develop complications of SIRS would be very useful.

The natural history of the systemic inflammatory response syndrome (SIRS). A prospective study

OBJECTIVE

Define the epidemiology of the four recently classified syndromes describing the biologic response to infection: systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, and septic shock.

DESIGN

Prospective cohort study with a follow-up of 28 days or until discharge if earlier.

SETTING

Three intensive care units and three general wards in a tertiary health care institution.

METHODS

Patients were included if they met at least two of the criteria for SIRS: fever or hypothermia, tachycardia, tachypnea, or abnormal white blood cell count.

MAIN OUTCOMES MEASURES

Development of any stage of the biologic response to infection: sepsis, severe sepsis, septic shock, end-organ dysfunction, and death.

RESULTS

During the study period 3708 patients were admitted to the survey units, and 2527 (68%) met the criteria for SIRS. The incidence density rates for SIRS in the surgical, medical, and cardiovascular intensive care units were 857, 804, and 542 episodes per 1000 patient-days, respectively, and 671, 495, and 320 per 1000 patient-days for the medical, cardiothoracic, and general surgery wards, respectively. Among patients with SIRS, 649 (26%) developed sepsis, 467 (18%) developed severe sepsis, and 110 (4%) developed septic shock. The median interval from SIRS to sepsis was inversely correlated with the number of SIRS criteria (two, three, or all four) that the patients met. As the population of patients progressed from SIRS to septic shock, increasing proportions had adult respiratory distress syndrome, disseminated intravascular coagulation, acute renal failure, and shock. Positive blood cultures were found in 17% of patients with sepsis, in 25% with severe sepsis, and in 69% with septic shock. There were also stepwise increases in mortality rates in the hierarchy from SIRS, sepsis, severe sepsis, and septic shock: 7%, 16%, 20%, and 46%, respectively. Of interest, we also observed equal numbers of patients who appeared to have sepsis, severe sepsis, and septic shock but who had negative cultures. They had been prescribed empirical antibiotics for a median of 3 days. The cause of the systemic inflammatory response in these culture-negative populations is unknown, but they had similar morbidity and mortality rates as the respective culture-positive populations.

CONCLUSIONS

This prospective epidemiologic study of SIRS and related conditions provides, to our knowledge, the first evidence of a clinical progression from SIRS to sepsis to severe sepsis and septic shock.

Infection control in Switzerland

Infection control in hospitals is not mandatory in Switzerland as in the United States. There are more than 300 acute-care hospitals in Switzerland. Hospitals are reimbursed by patient-days rather than diagnosis-related group. However, all five Swiss university hospitals have developed an infection control program. The major criteria for setting up and running these programs are reviewed; data are based on a questionnaire and personal interviewing of each institution. Most of the major criteria exist in all five institutions. Resources allocated to infection control differ markedly. The number of infection control nurses per 250 beds varies between 0.2 and 0.75 for the five hospitals; the activity of those in charge of infection control differs between hospitals. A comparison is made between the Swiss and U.S. programs with regard to some aspects of healthcare and infection control.

Candida colonization and subsequent infections in critically ill surgical patients

OBJECTIVE

The authors determined the role of Candida colonization in the development of subsequent infection in critically ill patients.

DESIGN

A 6-month prospective cohort study was given to patients admitted to the surgical and neonatal intensive care units in a 1600-bed university medical center.

METHODS

Patients having predetermined criteria for significant Candida colonization revealed by routine microbiologic surveillance cultures at different body sites were eligible for the study. Risk factors for Candida infection were recorded. A Candida colonization index was determined daily as the ratio of the number of distinct body sites (dbs) colonized with identical strains over the total number of dbs tested; a mean of 5.3 dbs per patient was obtained. All isolates (n = 322) sequentially recovered were characterized by genotyping using contour-clamped homogeneous electrical field gel electrophoresis that allowed strain delineation among Candida species.

RESULTS

Twenty-nine patients met the criteria for inclusion; all were at high risk for Candida infection; 11 patients (38%) developed severe infections (8 candidemia); the remaining 18 patients were heavily colonized, but never required intravenous antifungal therapy. Among the potential risk factors for candida infection, three discriminated the colonized from the infected patients--i.e., length of previous antibiotic therapy (p < 0.02), severity of illness assessed by APACHE II score (p < 0.01), and the intensity of Candida spp colonization (p < 0.01). By logistic regression analysis, the latter two who were the independent factors that predicted subsequent candidal infection. Candida colonization always preceded infection with genotypically identical Candida spp strain. The proposed colonization indexes reached threshold values a mean of 6 days before Candida infection and demonstrated high positive predictive values (66 to 100%).

CONCLUSIONS

The intensity of Candida colonization assessed by systematic screening helps predicting subsequent infections with identical strains in critically ill patients. Accurately identifying high-risk patients with Candida colonization offers opportunity for intervention strategies.

[Computer alert and quality of care: application to the surveillance of hospital infections]

The Centre Informatique of Geneva University Hospital is developing, in the environment of its hospital information system, DIOGENE, a computerized alert system for surveillance of hospital infections. This hospital information system is based on an open distributed architecture and a relational database system, and covers many medical applications. This environment allows the development of alerts useful for detecting patients at risk. The alerts offer to clinicians a mean to control their efficacy in patient care. They are a new application of telematics for surveillance in clinical epidemiology, and are a tool for quality assurance. Two examples of alerts established for hospital infection control activities are presented. The first alert systematically detects all cases of patients colonized by or infected with methicillin-resistant Staphylococcus aureus (MRSA). The second alert helps to organize prospective surveillance of bloodstream infections in order to identify some risk factors for infection and propose preventive measures.

Infectious risk factors related to operating rooms

Risk factors related to operating rooms include patient-associated risks, the operating room environment, ventilation systems, cleansing and sterilization, and operating room personnel. Although constantly debated, surgical wound infection surveillance with appropriate feedback to surgeons is one of the few effective measures that helps reduce surgical infection rates, and we strongly recommend its use. We also recommend the further study of other potential components of effective infection control programs for surgical patients.

Nosocomial bloodstream infection in critically ill patients. Excess length of stay, extra costs, and attributable mortality

OBJECTIVE

To determine the excess length of stay, extra costs, and mortality attributable to nosocomial bloodstream infection in critically ill patients.

DESIGN

Pairwise-matched (1:1) case-control study.

SETTING

Surgical intensive care unit (SICU) in a tertiary health care institution.

PATIENTS

All patients admitted in the SICU between July 1, 1988, and June 30, 1990, were eligible. Cases were defined as patients with nosocomial bloodstream infection; controls were selected according to matching variables in a stepwise fashion.

METHODS

Matching variables were primary diagnosis for admission, age, sex, length of stay before the day of infection in cases, and total number of discharge diagnoses. Matching was successful for 89% of the cohort; 86 matched case-control pairs were studied.

MAIN OUTCOME MEASURES

Crude and attributable mortality, excess length of hospital and SICU stay, and overall costs.

RESULTS

Nosocomial bloodstream infection complicated 2.67 per 100 admissions to the SICU during the study period. The crude mortality rates from cases and controls were 50% and 15%, respectively (P < .01); thus, the estimated attributable mortality rate was 35% (95% confidence interval, 25% to 45%). The median length of hospital stay significantly differed between cases and controls (40 vs 26 days, respectively; P < .01). When only matched pairs who survived bloodstream infection were considered (n = 41), cases stayed in the hospital a median of 54 days vs 30 days for controls (P < .01), and cases stayed in the SICU a median of 15 days vs 7 days for controls (P < .01). Thus, extra hospital and SICU length of stay attributable to bloodstream infection was 24 and 8 days, respectively. Extra costs attributable to the infection averaged $40,000 per survivor.

CONCLUSIONS

The attributable mortality from nosocomial bloodstream infection is high in critically ill patients. The infection is associated with a doubling of the SICU stay, an excess length of hospital stay of 24 days in survivors, and a significant economic burden.

Prospective randomized comparison of imipenem monotherapy with imipenem plus netilmicin for treatment of severe infections in nonneutropenic patients

Nosocomial pneumonia and sepsis, as well as severe diffuse peritonitis, must be treated early in order to prevent complications such as septic shock and organ dysfunctions. With the availability of new broad-spectrum and highly bactericidal antibiotics, the need of combining beta-lactams with aminoglycosides for the treatment of severe infections should be reassessed. A prospective randomized controlled study was performed to compare imipenem monotherapy with a combination of imipenem plus netilmicin in the empiric treatment of nosocomial pneumonia, nosocomial sepsis, and severe diffuse peritonitis. A total of 313 patients were enrolled, and 280 were assessable. The antibiotic treatment was successful in 113 of 142 patients (80%) given the monotherapy and in 119 of 138 patients (86%) given the combination (P = 0.19). The failure rates for the most important type of infection, i.e., pneumonia, were similar in the two groups, as well as the number of superinfections. While creatinine increase was associated with factors not related to antibiotic therapy for all eight patients of the monotherapy group, no factor other than the antibiotics could be found for 6 of the 14 cases of nephrotoxicity observed in the combination group (P = 0.014). Finally, the emergence of Pseudomonas aeruginosa resistant to imipenem occurred in 8 monotherapy patients and in 13 combination therapy patients. In conclusion, imipenem monotherapy appeared as effective as the combination of imipenem plus netilmicin for the treatment of severe infection. The addition of netilmicin increased nephrotoxicity, and it did not prevent the emergence of P. aeruginosa resistant to imipenem.

Nosocomial bloodstream infection in critically ill patients. Excess length of stay, extra costs, and attributable mortality

OBJECTIVE

To determine the excess length of stay, extra costs, and mortality attributable to nosocomial bloodstream infection in critically ill patients.

DESIGN

Pairwise-matched (1:1) case-control study.

SETTING

Surgical intensive care unit (SICU) in a tertiary health care institution.

PATIENTS

All patients admitted in the SICU between July 1, 1988, and June 30, 1990, were eligible. Cases were defined as patients with nosocomial bloodstream infection; controls were selected according to matching variables in a stepwise fashion.

METHODS

Matching variables were primary diagnosis for admission, age, sex, length of stay before the day of infection in cases, and total number of discharge diagnoses. Matching was successful for 89% of the cohort; 86 matched case-control pairs were studied.

MAIN OUTCOME MEASURES

Crude and attributable mortality, excess length of hospital and SICU stay, and overall costs.

RESULTS

Nosocomial bloodstream infection complicated 2.67 per 100 admissions to the SICU during the study period. The crude mortality rates from cases and controls were 50% and 15%, respectively (P < .01); thus, the estimated attributable mortality rate was 35% (95% confidence interval, 25% to 45%). The median length of hospital stay significantly differed between cases and controls (40 vs 26 days, respectively; P < .01). When only matched pairs who survived bloodstream infection were considered (n = 41), cases stayed in the hospital a median of 54 days vs 30 days for controls (P < .01), and cases stayed in the SICU a median of 15 days vs 7 days for controls (P < .01). Thus, extra hospital and SICU length of stay attributable to bloodstream infection was 24 and 8 days, respectively. Extra costs attributable to the infection averaged $40,000 per survivor.

CONCLUSIONS

The attributable mortality from nosocomial bloodstream infection is high in critically ill patients. The infection is associated with a doubling of the SICU stay, an excess length of hospital stay of 24 days in survivors, and a significant economic burden.

[Nosocomial pneumonia: incidence, morbidity and mortality in the intubated-ventilated patient]

Pneumonia is the leading nosocomial infection in critically ill patients. Its exact frequency is not known because of lack of specificity of the clinical diagnosis and existing standard techniques: ventilator-associated pneumonia (VAP) complicates 7 to 44 (mean 25) per 100 admissions. According to the results of matched case-control studies, VAP is associated with a prolongation of the duration of mechanical ventilation, time in ICU and hospital stay. Estimated extra costs due to VAP average 13,000 SFr per patient (28,000 SFr per survivor). Overall mortality associated with VAP ranges from 40 to 80%, varying with the severity of the underlying illness. Mortality attributable only to the infection accounts for a third of deaths in patients with VAP.

Second messenger specificity of the inositol trisphosphate receptor: reappraisal based on novel inositol phosphates

To further understand how the second messenger D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] interacts with its intracellular receptor, we injected 47 highly purified inositol phosphate (InsP) positional isomers in Xenopus oocytes and compared their potency in releasing intracellular Ca2+. The potency of the Ca(2+)-releasing InsPs spanned four orders of magnitude. Seven compounds, including the novel inositol 1,2,4,5-tetrakisphosphate [D/L-Ins (1,2,4,5)P4] and D/L-Ins(1,4,6)P3, had a very high potency. All of these highly active InsPs shared the following structure: two D-trans-equatorial phosphates (eq-P) and one equatorial hydroxyl (eq-OH) attached to ring carbons D-4, D-5, and D-6 (or to the structurally equivalent D-1, D-6, and D-5 carbons). This permissive structure was not sufficient for Ca2+ release, because it was also found in two inactive compounds, Ins(1,6)P2 and Ins(1,3,6)P3. To be active, InsPs also required the structural equivalent of a D-3 eq-OH and/or a D-1 eq-P. Together, our data reveal how the structure of the InsP molecule affects its ability to release Ca2+.