Effect of Combination Antibiotic Empirical Therapy on Mortality in Neutropenic Cancer Patients with Pseudomonas aeruginosa Pneumonia

Clinical Characteristics and Optimization of Empirical Antimicrobial Therapy for Febrile Neutropenia in Patients With Hematologic Malignancies

Purpose

Since the publication of the 2011 Infectious Diseases Society of America (IDSA) guidelines for empirical treatment of febrile neutropenia (FN), there have been significant shifts in pathogen profiles and emerging challenges in treatment. These include increased prevalence of multidrug-resistant (MDR) bacteria and changes in the distribution of Gram-negative or Gram-positive bacteria (GPB). The study aims to update and optimize empirical treatment strategies for hematological malignancy (HM) patients, a population particularly vulnerable to these evolving threats.

Methods

A literature review was conducted on studies published between January 2010 and December 2023 regarding empirical treatment of FN in HM patients, focusing on pathogen characteristics, treatment regimens, and duration of therapy.

Results

Approximately one-third of HM patients with FN experience fever of unknown origin (FUO), while 40-50% have clinically documented infections (CDI), and 10-30% present with microbiologically documented infections (MDI), with a predominance of Gram-negative bacteria (GNB). Factors such as prolonged neutropenia, prior broad-spectrum antibiotic use, and previous infections with drug-resistant bacteria are associated with MDR infections. Cefepime, piperacillin/tazobactam (PTZ), and carbapenem are viable empirical treatments for high-risk HM patients, though cefepime monotherapy's advantage remains uncertain. In cases of pneumonia, shock, or suspected carbapenem-resistant infections, combination therapy, tigecycline, and newer antibiotics like ceftazidime/avibactam (CAZ/AVI) are often used. Empirical broad-spectrum antibiotics can be safely discontinued in FUO patients after 48 hours of clinical stability and apyrexia.

Conclusion

Proper selection of empirical antibiotics and determining optimal treatment duration are essential for reducing antibiotic resistance and improving outcomes in HM patients with FN. These findings underscore the need for updated clinical guidelines that address evolving pathogen profiles and the growing challenge of MDR infections.

Effect of empiric antibiotics against Pseudomonas aeruginosa on mortality in hospitalized patients: a systematic review and meta-analysis

BACKGROUND

Empiric antibiotics active against Pseudomonas aeruginosa are recommended by professional societies for certain infections and are commonly prescribed for hospitalized patients. The effect of this practice on mortality is uncertain.

METHODS

A systematic literature search was conducted using Embase, Medline, PubMed, Web of Science, Cochrane, Scopus and Google Scholar from earliest entry through 9 October 2023. We included studies of patients hospitalized with P. aeruginosa infections that compared mortality rates depending on whether patients received active empiric antibiotics.

RESULTS

We found 27 studies of 12 522 patients that reported adjusted OR of active empiric antibiotics on mortality. The pooled adjusted OR was 0.40 (95% CI, 0.32-0.50), favouring active empiric antibiotics. In practice, the mortality effect of empiric antibiotics against P. aeruginosa depends on the prevalence of P. aeruginosa and baseline mortality. The estimated absolute mortality benefit was 0.02% (95% CI, 0.02-0.02) for soft tissue infections, 0.12% (95% CI, 0.10-0.13) for urinary tract infections and community-acquired pneumonia, 0.3% (0.25-0.34) for sepsis without shock, 1.1% (95% CI, 0.9-1.4) for septic shock and 2.4% (95% CI, 1.9-2.8) for nosocomial pneumonia.

CONCLUSIONS

The mortality effect for empiric antibiotics against P. aeruginosa depends crucially on the prevalence of P. aeruginosa and baseline mortality by type of infection. For soft tissue infections, urinary tract infections and community-acquired pneumonia, the mortality benefit is low. Meaningful benefit of empiric antibiotics against P. aeruginosa is limited to patients with approximately 30% mortality and 5% prevalence of P. aeruginosa, which is largely limited to patients in intensive care settings.

Impact of adequate empirical combination therapy on mortality in septic shock due to Pseudomonas aeruginosa bloodstream infections: a multicentre retrospective cohort study

OBJECTIVES

To determine the association of adequate empirical combination therapy (AECT) with 30-day all-cause mortality in patients with septic shock due to Pseudomonas aeruginosa bloodstream infections (BSI).

METHODS

This multicentre, retrospective cohort study analysed data from 14 public hospitals in Italy, including all consecutive adult patients admitted during 2021-2022 with septic shock due to P. aeruginosa BSI. We compared the outcomes of patients receiving AECT to those on adequate empirical monotherapy (AEMT) using Cox regression analyses.

RESULTS

Of the 98 patients who received adequate empirical antibiotic treatment for septic shock due to P. aeruginosa BSI, 24 underwent AECT and 74 were given AEMT. AECT was associated with a lower 30-day all-cause mortality (25%, six out of 24) compared to AEMT (56.8%, 42 out of 74; P = 0.007). Multivariate Cox regression analysis indicated AECT as the only factor significantly associated with improved survival (aHR 0.30; 95% CI 0.12-0.71; P = 0.006). By contrast, the use of monotherapy or combination therapy in the definitive regimen did not influence mortality (aHR 0.73; 95% CI 0.25-2.14; P = 0.568).

CONCLUSIONS

AECT may be associated with reduced mortality compared to monotherapy in septic shock patients due to P. aeruginosa BSI. However, the administration of definitive adequate monotherapy or combination therapy yields similar outcomes, suggesting that once susceptibility is documented, switching to a single active in vitro drug is safe and feasible. Further studies are recommended to validate these findings.

Pseudomonas aeruginosa Bloodstream Infections Presenting with Septic Shock in Neutropenic Cancer Patients: Impact of Empirical Antibiotic Therapy

This large, multicenter, retrospective cohort study including onco-hematological neutropenic patients with Pseudomonas aeruginosa bloodstream infection (PABSI) found that among 1213 episodes, 411 (33%) presented with septic shock. The presence of solid tumors (33.3% vs. 20.2%, p < 0.001), a high-risk Multinational Association for Supportive Care in Cancer (MASCC) index score (92.6% vs. 57.4%; p < 0.001), pneumonia (38% vs. 19.2% p < 0.001), and infection due to multidrug-resistant P. aeruginosa (MDRPA) (33.8% vs. 21.1%, p < 0.001) were statistically significantly higher in patients with septic shock compared to those without. Patients with septic shock were more likely to receive inadequate empirical antibiotic therapy (IEAT) (21.7% vs. 16.2%, p = 0.020) and to present poorer outcomes, including a need for ICU admission (74% vs. 10.5%; p < 0.001), mechanical ventilation (49.1% vs. 5.6%; p < 0.001), and higher 7-day and 30-day case fatality rates (58.2% vs. 12%, p < 0.001, and 74% vs. 23.1%, p < 0.001, respectively). Risk factors for 30-day case fatality rate in patients with septic shock were orotracheal intubation, IEAT, infection due to MDRPA, and persistent PABSI. Therapy with granulocyte colony-stimulating factor and BSI from the urinary tract were associated with improved survival. Carbapenems were the most frequent IEAT in patients with septic shock, and the use of empirical combination therapy showed a tendency towards improved survival. Our findings emphasize the need for tailored management strategies in this high-risk population.

Advances in antibacterial treatment of adults with high-risk febrile neutropenia

BACKGROUND

High-risk febrile neutropenia (HR-FN) is a life-threatening complication in patients with haematological malignancies or receiving myelosuppressive chemotherapy. Since the last international guidelines were published over 10 years ago, there have been major advances in the understanding and management of HR-FN, including on antibiotic pharmacokinetics and discontinuation/de-escalation strategies.

OBJECTIVES

Summarizing major advances in the field of antibacterial therapy in patients with HR-FN: empirical therapy, pharmacokinetics of antibiotics and antibiotic stewardship.

SOURCES

Narrative review based on literature review from PubMed. We focused on studies published between 2010 and 2023 about the pharmacokinetics of antimicrobials, management of antimicrobial administration, and discontinuation/de-escalation strategies. We did not address antimicrobial prophylaxis, viral or fungal infections.

CONTENT

Several high-quality publications have highlighted important modifications of antibiotic pharmacokinetics in HR-FN, with standard dosages exposing patients to underdosing. These recent clinical and population pharmacokinetics studies help improve management protocols with optimized initial dosing and infusion rules for β-lactams, vancomycin, daptomycin and amikacin; they highlight the potential benefits of therapeutic drug monitoring. A growing body of evidence also shows that antibiotic discontinuation/de-escalation strategies are beneficial for bacterial ecology and patients' outcome. We further discuss methods and limitations for implementation of such protocols in haematology.

IMPLICATIONS

We highlight recent information about the management of antibacterial therapy in HR-FN that might be considered in updated guidelines for HR-FN management.

High Rate of Inappropriate Antibiotics in Patients with Hematologic Malignancies and Pseudomonas aeruginosa Bacteremia following International Guideline Recommendations

Optimal coverage of Pseudomonas aeruginosa is challenging in febrile neutropenic patients due to a progressive increase in antibiotic resistance worldwide. We aimed to detail current rates of resistance to antibiotics recommended by international guidelines for P. aeruginosa isolated from bloodstream infections (BSI) in patients with hematologic malignancies. Secondarily, we aimed to describe how many patients received inappropriate empirical antibiotic treatment (IEAT) and its impact on mortality. We conducted a retrospective, multicenter cohort study of the last 20 BSI episodes caused by P. aeruginosa in patients with hematologic malignancies from across 14 university hospitals in Spain. Of the 280 patients with hematologic malignancies and BSI caused by P. aeruginosa, 101 (36%) had strains resistant to at least one of the β-lactam antibiotics recommended in international guidelines, namely, cefepime, piperacillin-tazobactam, and meropenem. Additionally, 21.1% and 11.4% of the strains met criteria for MDR and XDR P. aeruginosa, respectively. Even if international guidelines were followed in most cases, 47 (16.8%) patients received IEAT and 66 (23.6%) received inappropriate β-lactam empirical antibiotic treatment. Thirty-day mortality was 27.1%. In the multivariate analysis, pulmonary source (OR 2.22, 95% CI 1.14 to 4.34) and IEAT (OR 2.67, 95% CI 1.37 to 5.23) were factors independently associated with increased mortality. We concluded that P. aeruginosa-causing BSI in patients with hematologic malignancies is commonly resistant to antibiotics recommended in international guidelines, which is associated with frequent IEAT and higher mortality. New therapeutic strategies are needed. IMPORTANCE Bloodstream infection (BSI) caused by P. aeruginosa is related with an elevated morbidity and mortality in neutropenic patients. For this reason, optimal antipseudomonal coverage has been the basis of all historical recommendations in the empirical treatment of febrile neutropenia. However, in recent years the emergence of multiple types of antibiotic resistances has posed a challenge in treating infections caused by this microorganism. In our study we postulated that P. aeruginosa-causing BSI in patients with hematologic malignancies is commonly resistant to antibiotics recommended in international guidelines. This observation is associated with frequent IEAT and increased mortality. Consequently, there is a need for a new therapeutic strategy.

Antimicrobial Treatment of Pseudomonas aeruginosa Severe Sepsis

Pseudomonas aeruginosa is a pathogen often encountered in a healthcare setting. It has consistently ranked among the most frequent pathogens seen in nosocomial infections, particularly bloodstream and respiratory tract infections. Aside from having intrinsic resistance to many antibiotics, it rapidly acquires resistance to novel agents. Given the high mortality of pseudomonal infections generally, and pseudomonal sepsis particularly, and with the rise of resistant strains, treatment can be very challenging for the clinician. In this paper, we will review the latest evidence for the optimal treatment of P. aeruginosa sepsis caused by susceptible as well as multidrug-resistant strains including the difficult to treat pathogens. We will also discuss the mode of drug infusion, indications for combination therapy, along with the proper dosing and duration of treatment for various conditions with a brief discussion of the use of non-antimicrobial agents.

Pseudomonas aeruginosa Bloodstream Infections in Patients with Cancer: Differences between Patients with Hematological Malignancies and Solid Tumors

Objectives: To assess the clinical features and outcomes of Pseudomonas aeruginosa bloodstream infection (PA BSI) in neutropenic patients with hematological malignancies (HM) and with solid tumors (ST), and identify the risk factors for 30-day mortality. Methods: We performed a large multicenter, retrospective cohort study including onco-hematological neutropenic patients with PA BSI conducted across 34 centers in 12 countries (January 2006−May 2018). Episodes occurring in hematologic patients were compared to those developing in patients with ST. Risk factors associated with 30-day mortality were investigated in both groups. Results: Of 1217 episodes of PA BSI, 917 occurred in patients with HM and 300 in patients with ST. Hematological patients had more commonly profound neutropenia (0.1 × 109 cells/mm) (67% vs. 44.6%; p < 0.001), and a high risk Multinational Association for Supportive Care in Cancer (MASCC) index score (32.2% vs. 26.7%; p = 0.05). Catheter-infection (10.7% vs. 4.7%; p = 0.001), mucositis (2.4% vs. 0.7%; p = 0.042), and perianal infection (3.6% vs. 0.3%; p = 0.001) predominated as BSI sources in the hematological patients, whereas pneumonia (22.9% vs. 33.7%; p < 0.001) and other abdominal sites (2.8% vs. 6.3%; p = 0.006) were more common in patients with ST. Hematological patients had more frequent BSI due to multidrug-resistant P. aeruginosa (MDRPA) (23.2% vs. 7.7%; p < 0.001), and were more likely to receive inadequate initial antibiotic therapy (IEAT) (20.1% vs. 12%; p < 0.001). Patients with ST presented more frequently with septic shock (45.8% vs. 30%; p < 0.001), and presented worse outcomes, with increased 7-day (38% vs. 24.2%; p < 0.001) and 30-day (49% vs. 37.3%; p < 0.001) case-fatality rates. Risk factors for 30-day mortality in hematologic patients were high risk MASCC index score, IEAT, pneumonia, infection due to MDRPA, and septic shock. Risk factors for 30-day mortality in patients with ST were high risk MASCC index score, IEAT, persistent BSI, and septic shock. Therapy with granulocyte colony-stimulating factor was associated with survival in both groups. Conclusions: The clinical features and outcomes of PA BSI in neutropenic cancer patients showed some differences depending on the underlying malignancy. Considering these differences and the risk factors for mortality may be useful to optimize their therapeutic management. Among the risk factors associated with overall mortality, IEAT and the administration of granulocyte colony-stimulating factor were the only modifiable variables.

Three-Year Evaluation of Pseudomonas aeruginosa Bacteremia in Patients Admitted to a University-Affiliated Hospital, Mashhad, Iran

Background: Pseudomonas aeruginosa is an opportunistic gram-negative pathogen that can cause infection in almost any body part. Objectives: We aimed to evaluate the characteristics of patients with P. aeruginosa bloodstream infection (BSI). Methods: In this cross-sectional study, we retrospectively evaluated the records of 35 patients with P. aeruginosa BSI admitted to the Imam Reza Hospital, Mashhad, Iran, during 2012 - 2015. Age, sex, clinical symptoms, risk factors, underlying diseases, and the antibiogram test results were recorded and compared between nosocomial and community-acquired infection (CAI) dead and alive patients using the chi-square test. Data were analyzed using SPSS software, version 21. Results: The patients had a mean age of 54.57 ± 20.75 years, with 19 of them being men (54.3%). Intubation was only required in the deceased group (N = 19; P = 0.014). Tachypnea was more frequent (63.2% vs. 13.2%, P = 0.003), and appropriate treatment was less frequent (27.8% vs. 66.7%; P = 0.02) in the deceased group compared to the control group. Most patients with nosocomial infection (N = 24) passed away (66.7%; P = 0.03). All nine patients with a history of burning had a nosocomial infection (P = 0.01). Shivering and decreased consciousness were more frequent in patients with CAI (both P = 0.03) than in other patients. The antibiogram test results showed high resistance to multiple antibiotics. Conclusions: Considering the high mortality rate of P. aeruginosa BSI and resistance to multiple antibiotics, it is necessary to pay greater attention to the prevention of nosocomial infection with this pathogen, especially in patients admitted to burn centers and those with specific clinical signs, like tachypnea and leukocytosis.