Analysis of 553 episodes of monomicrobial bacteraemia in cancer patients: any association between risk factors and outcome to particular pathogen?

Digital imaging for reading of direct rapid antibiotic susceptibility tests from positive blood cultures

Delaying effective antibiotic therapy is a major cause of sepsis-associated mortality. The EUCAST rapid antibiotic susceptibility test (RAST) is performed from positive blood cultures to provide rapid results. Disc diffusion tests inoculated with positive blood culture broth are read at 4, 6, and 8 h and interpreted against species and time-specific criteria. Potential problems are the possibility of missing specific reading times for tests and slower growth in incubators that are frequently opened. The current study aimed to assess if digital visualization by the BD Kiestra™ total laboratory automation system is suitable for reading RASTs by capturing images at the correct times and retaining them for review. Utilizing the Kiestra™ InoqulA, 100 μl of positive blood culture broth was lawn-inoculated onto Mueller-Hinton agar and incubated at 35 °C for automated digital zone measurement at 4, 6, and 8 h. Aliquots from 135 positive blood cultures were tested against EUCAST-recommended and other drugs and assessed for readability of digital images. Microdilution MICs were determined in parallel to RASTs. All isolates except 7/10 enterococci yielded images of suitable quality for zone measurement. Of the 641 digitally read tests for other organisms, 207 (32.3%) were readable in 4 h, 555 (86.6%) in 6 h, and 641 (100%) in 8 h. For tests included in EUCAST criteria, 92.1% provided categorical agreement with microdilution MICs. Digital image reading of RASTs is a potentially viable, inexpensive tool for providing rapid susceptibility results which can help reduce sepsis-associated mortality.

Inappropriate Empirical Antibiotic Treatment in High-risk Neutropenic Patients With Bacteremia in the Era of Multidrug Resistance

BACKGROUND

We aimed to describe the current rates of inappropriate empirical antibiotic treatment (IEAT) in oncohematological patients with febrile neutropenia (FN) and its impact on mortality.

METHODS

This was a multicenter prospective study of all episodes of bloodstream infection (BSI) in high-risk FN patients (2006-2017). Episodes receiving IEAT were compared with episodes receiving appropriate empirical therapy. Adherence to Infectious Diseases Society of America (IDSA) recommendations was evaluated. Multivariate analysis was performed to identify independent risk factors for mortality in Pseudomonas aeruginosa episodes.

RESULTS

Of 1615 episodes, including Escherichia coli (24%), coagulase-negative staphylococci (21%), and P. aeruginosa (16%), 394 (24%) received IEAT despite IDSA recommendations being followed in 87% of cases. Patients with multidrug-resistant gram-negative bacilli (MDR-GNB), accounting for 221 (14%) of all isolates, were more likely to receive IEAT (39% vs 7%, P < .001). Overall mortality was higher in patients with GNB BSI who received IEAT (36% vs 24%, P = .004); when considering individual microorganisms, only patients with infection caused by P. aeruginosa experienced a significant increase in mortality when receiving IEAT (48% vs 31%, P = .027). Independent risk factors for mortality in PA BSI (odds ratio [95% confidence interval] were IEAT (2.41 [1.19-4.91]), shock at onset (4.62 [2.49-8.56]), and pneumonia (3.01 [1.55-5.83]).

CONCLUSIONS

IEAT is frequent in high-risk patients with FN and BSI, despite high adherence to guidelines. This inappropriate treatment primarily impacts patients with P. aeruginosa-related BSI mortality and in turn is the only modifiable factor to improve outcomes.

Clinical Predictive Model of Multidrug Resistance in Neutropenic Cancer Patients with Bloodstream Infection Due to Pseudomonas aeruginosa

We aimed to assess the rate and predictive factors of bloodstream infection (BSI) due to multidrug-resistant (MDR) Pseudomonas aeruginosa in neutropenic cancer patients. We performed a multicenter, retrospective cohort study including oncohematological neutropenic patients with BSI due to P. aeruginosa conducted across 34 centers in 12 countries from January 2006 to May 2018. A mixed logistic regression model was used to estimate a model to predict the multidrug resistance of the causative pathogens. Of a total of 1,217 episodes of BSI due to P. aeruginosa, 309 episodes (25.4%) were caused by MDR strains. The rate of multidrug resistance increased significantly over the study period (P = 0.033). Predictors of MDR P. aeruginosa BSI were prior therapy with piperacillin-tazobactam (odds ratio [OR], 3.48; 95% confidence interval [CI], 2.29 to 5.30), prior antipseudomonal carbapenem use (OR, 2.53; 95% CI, 1.65 to 3.87), fluoroquinolone prophylaxis (OR, 2.99; 95% CI, 1.92 to 4.64), underlying hematological disease (OR, 2.09; 95% CI, 1.26 to 3.44), and the presence of a urinary catheter (OR, 2.54; 95% CI, 1.65 to 3.91), whereas older age (OR, 0.98; 95% CI, 0.97 to 0.99) was found to be protective. Our prediction model achieves good discrimination and calibration, thereby identifying neutropenic patients at higher risk of BSI due to MDR P. aeruginosa The application of this model using a web-based calculator may be a simple strategy to identify high-risk patients who may benefit from the early administration of broad-spectrum antibiotic coverage against MDR strains according to the local susceptibility patterns, thus avoiding the use of broad-spectrum antibiotics in patients at a low risk of resistance development.

Outcomes of Nosocomial Bloodstream Infections in Adult Neutropenic Patients: A Prospective Cohort and Matched Case-Control Study

Objective:

To examine the clinical and epidemiologic features, excess length of stay, extra costs, and mortality attributable to bloodstream infection (BSI) in neutropenic patients with hematologic malignancies.

Design:

Prospective cohort and matched case-control study.

Patients:

All adult neutropenic patients with hematologic malignancies admitted to Cologne University Hospital between May 1, 1997, and April 30, 1998, were prospectively observed. Case-patients were defined as patients with nosocomial BSI; control-patients were selected among patients without BSI.

Results:

During the study period, the BSI rate in neutropenic patients was 14.3 per 100 neutropenic episodes. Eighty-four case-patients were included. Matching was successful for 96% of the cohort; 81 matched pairs were studied. The mean total length of stay was significantly longer for patients with BSI than for control-patients (37 vs 29 days;P= .002). Extra costs attributable to the infection averaged $3,200 (U.S.) per patient. The crude mortality rates of case-patients and control-patients were 16% and 4%, respectively (P= .013), with an attributable mortality of 12% (odds ratio, 11). Eighty-seven percent of patients met the criteria for sepsis according to the American College of Chest Physicians/Society of Critical Care Medicine. Severe sepsis or septic shock occurred in 13% of patients and was correlated with mortality (55% vs 10% in patients without severe sepsis or septic shock;P=.01).

Conclusions:

Nosocomial BSI in neutropenic patients is significantly associated with an excess length of hospital stay, extra costs, and excess mortality. Severe sepsis and septic shock are closely correlated with an adverse outcome.

Bloodstream infections in patients with or without cancer in a large community hospital

PURPOSE

Cancer is associated with an increased risk of acquiring bloodstream infection (BSIs). Most knowledge on pathogens and outcome are derived from specialised cancer centres. We here sought to compare causative micro-organisms in BSIs in patients with or without cancer in a 600-bed teaching community hospital.

METHODS

We analysed all positive blood cultures from adult patients between January 2005 and January 2011.

RESULTS

A total of 4,918 episodes of BSI occurred in 2,891 patients, of whom 13.4% had a diagnosis of cancer (85.5% with a solid tumour). In both patient groups, Gram-positive isolates were more prevalent (58.7 and 61.4% in patients with and without cancer, respectively) than Gram-negative isolates (31.8 and 32.3%, respectively). Amongst Gram-positive organisms, coagulase-negative staphylococci, Staphylococcus aureus and enterococci were the most frequently isolated in both patient groups; in cancer patients, twice as many BSIs were caused by Enterococcus faecalis and E. faecium. Amongst Gram-negative organisms, Escherichia coli was the most common isolate; in cancer patients, twice as many BSIs were caused by Pseudomonas aeruginosa and Enterobacter cloacae. Yeasts were grown from 3.0% of blood cultures from cancer patients compared to 1.5% of cultures from non-cancer patients. Cancer patients had a 90-day mortality of 35.8% following BSI compared to 23.5% in patients without cancer.

CONCLUSION

These data demonstrate distinct BSI pathogens and impaired outcomes in patients with cancer in the setting of a large community teaching hospital.

Hypercortisolemia and Infection

Hypercortisolemia is a condition involving a prolonged excess of serum levels of cortisol that can develop as a result of disregulatory abnormalities in the hypothalamic-pituitary-adrenal axis or from exogenous-source steroids. Hypercortisolemia induces a state of immunocompromise that predisposes the patient to various bacterial, viral, fungal, and parasitic infections. To ensure optimal management of hypercortisolemia, the primary clinician must be cognizant of its different causes and aware of the different infections associated with cortisol excess. In the hypercortisolemic patient, it is necessary to restore normal cortisol levels to reduce the risk of infection or to improve the control and cure of established infection.

Bacteremias: a leading cause of death

Bloodstream infections (BSIs), recognized to be a major cause of morbidity and mortality globally, are increasing in incidence. The reported rates of crude and attributable mortality vary, possibly due to heterogeneity in patient populations and methodology. Few studies, however, have focused on pathogen-specific attributable mortality. These studies include S. aureus, coagulase-negative staphylococci and enterococcus. Other studies of attributable mortality have been conducted in select populations such as nosocomial and community-acquired cohorts, intensive care units, neutropenic patients, and HIV-positive patients. Regrettably, despite advances in treatment and intensive care facilities, mortality remains high.

Current trends in the epidemiology of nosocomial bloodstream infections in patients with hematological malignancies and solid neoplasms in hospitals in the United States

A total of 2340 patients with underlying malignancy were identified among 22,631 episodes of nosocomial bloodstream infections (BSIs) in a prospectively collected database for 49 hospitals in the United States (Surveillance and Control of Pathogens of Epidemiologic Importance [SCOPE] Project). Data were obtained for the period of March 1995 through February 2001. Gram-positive organisms accounted for 62% of all BSIs in 1995 and for 76% in 2000 (P<.001), and gram-negative organisms accounted for 22% and 14% of all BSIs for these years, respectively. Neutropenia was observed in 30% of patients, so neutropenic and nonneutropenic patients were compared. In both, the predominant pathogens were coagulase-negative staphylococci (32% of isolates recovered from neutropenic patients and 30% of isolates recovered from nonneutropenic patients). The source of BSI was not determined for 57% of patients. The crude mortality rate was 36% for neutropenic patients and 31% for nonneutropenic patients.

[Incidence of bacteremia among histologic groups of hematologic malignancies]

INTRODUCTION

Subgroups having dissimilar prognoses are being identified among cancer patients with infection. Previous studies have suggested that these differences may be related to the histologic diagnosis, but this issue has not as yet been demonstrated.

METHODS

We reviewed the medical records of all patients admitted with acute leukemia (AL) or lymphoma (ML) from 1988 to 1998. Incidence of bacteremia was calculated for the following subgroups: acute lymphocytic leukemia (ALL), acute myelocytic leukemia (AML), AML following refractory anaemia with excess blasts (AML-RAEB), high-grade ML (HGML), intermediate-grade ML (IGML), low-grade ML (LGML) and indeterminate ML (IML). Kaplan-Meier curves of time to the first positive blood culture were constructed and compared by means of log-rank test.

RESULTS

In the period covered there were 244 new diagnoses of AL or ML: 62 AML, 32 ALL, 20 AML-RAEB, 78 HGML, 7 IGML, 37 LGML and 6 IML. At the end of the study period, 44 patients were alive, 147 were known to have died at a certain date and 53 had been formally lost to follow-up (most of them, transferred for hospice care). Among 684 blood cultures, there were 51 contaminations and 155 significant isolates. Among the latter, gram-positive bacteria were isolated in 74 and gram-negative bacteria in 47; in 27 cases more than 1 bacterial species were recovered. Fungi were isolated in 7 cases. The incidence of bacteremia expressed as cases per 1000 patient-days was 5.80 for AML, 5.03 for AML-RAEB, 1.56 for ALL, 0.21 for HGML and 0.40 for the remaining ML. Time to the first positive blood culture was significantly shorter for AML than for any other group, and was shorted for ALL and AML-RAEB than for ML.

CONCLUSION

Differences in the incidence of bacteremia were observed among histologically-defined groups of unselected patients with hematologic malignancies.

Pseudomonas aeruginosa infections in cancer patients: have they gone away?

Pseudomonas aeruginosa infection continues to be a threat to cancer patients, especially if they are neutropenic. As many as 50% of infections are community acquired. Prompt, effective therapy results in cures in about 80% of patients, although the presence of shock or pneumonia indicates a poor prognosis. Antibiotic resistance is an increasing problem.

Pneumonia in the compromised host including cancer patients and transplant patients

Pneumonia remains a major cause of morbidity and mortality in the immunocompromised host. The type and timing of immunosuppression will predispose the patient to infections with certain pathogens. This article discusses the types of immunosuppression and their infectious and noninfectious implications. Key points of the most commonly involved pathogens are mentioned. Finally, an approach to diagnosis and empiric therapy is discussed.