Invasive pulmonary aspergillosis resulting in respiratory failure during neutrophil recovery from postchemotherapy neutropenia in three patients with acute leukaemia

Pathogenicity and virulence of Aspergillus fumigatus

Pulmonary infections caused by the mould pathogen Aspergillus fumigatus are a major cause of morbidity and mortality globally. Compromised lung defences arising from immunosuppression, chronic respiratory conditions or more recently, concomitant viral or bacterial pulmonary infections are recognised risks factors for the development of pulmonary aspergillosis. In this review, we will summarise our current knowledge of the mechanistic basis of pulmonary aspergillosis with a focus on emerging at-risk populations.

Clinical manifestations and outcomes of pulmonary aspergillosis: experience from Pakistan

Introduction

Pulmonary aspergillosis has variable course of illness, severity and outcomes depending on underlying conditions. There is limited data available on the clinical manifestations and outcome of pulmonary aspergillosis from Pakistan.

Methods

To determine the clinical manifestations and outcome of pulmonary aspergillosis in a tertiary care hospital a retrospective study was conducted from 2004 to 2014 in patients admitted with pulmonary aspergillosis at the Aga Khan University Hospital Karachi, Pakistan.

Results

Of the 280 cases with provisional diagnosis of aspergillosis 69 met the inclusion criteria. The mean age was 45±15.7 years, 48 (69.6%) were men and 21 (30.4%) had diabetes mellitus (DM). The average length of hospital stay (LOS) was 10.61±9.08 days. Aspergillus fumigatus was the most common (42.0%), followed by Aspergillus flavus (28.9%). More than one-third of patients previously had tuberculosis (TB) (39.13%). The commonest pulmonary manifestation was chronic pulmonary aspergillosis (CPA) 47 (68.1%) followed by invasive pulmonary aspergillosis (IPA) 12 (17.4%) and subacute invasive aspergillosis (SAIA) 8 (11.6%). Surgical excision was performed in 28 patients (40.57%). Intensive care unit admission was required for 18 patients (26.08%). Case fatality rate was 14/69 (20.3%). DM, mean LOS and hypoxic respiratory failure were identified as independent risk factors of mortality on multivariate analysis.

Conclusion

A. fumigatus was the most frequent species found especially in patients with prior TB. CPA was the commonest pulmonary manifestation seen as post TB sequel. Diabetes, hypoxic respiratory failure and increased LOS were independent predictors of poor outcomes. Overall patients had good outcome with CPA compared with SAIA and IPA.

Reducing hypoxia and inflammation during invasive pulmonary aspergillosis by targeting the Interleukin-1 receptor

Hypoxia as a result of pulmonary tissue damage due to unresolved inflammation during invasive pulmonary aspergillosis (IPA) is associated with a poor outcome. Aspergillus fumigatus can exploit the hypoxic microenvironment in the lung, but the inflammatory response required for fungal clearance can become severely disregulated as a result of hypoxia. Since severe inflammation can be detrimental to the host, we investigated whether targeting the interleukin IL-1 pathway could reduce inflammation and tissue hypoxia, improving the outcome of IPA. The interplay between hypoxia and inflammation was investigated by in vivo imaging of hypoxia and measurement of cytokines in the lungs in a model of corticosteroid immunocompromised and in Cxcr2 deficient mice. Severe hypoxia was observed following Aspergillus infection in both models and correlated with development of pulmonary inflammation and expression of hypoxia specific transcripts. Treatment with IL-1 receptor antagonist reduced hypoxia and slightly, but significantly reduced mortality in immunosuppressed mice, but was unable to reduce hypoxia in Cxcr2(-/-) mice. Our data provides evidence that the inflammatory response during invasive pulmonary aspergillosis, and in particular the IL-1 axis, drives the development of hypoxia. Targeting the inflammatory IL-1 response could be used as a potential immunomodulatory therapy to improve the outcome of aspergillosis.

Worsening of Respiratory Status during Neutropenia Recovery in Noncritically Ill Hematological Patients: Results of a Prospective Multicenter Study

<b><i>Background:</i></b> Neutropenia recovery (NR) has been associated with worsening preexisting lung injury in up to 50% of critically ill cancer patients. However, only limited relevant data exist in the general population of hematological patients. <b><i>Objectives:</i></b> To assess the incidence of acute respiratory deterioration during NR in patients with hematological malignancies. <b><i>Methods:</i></b> Adult patients with neutropenia expected to last more than 7 days were included. Worsening of respiratory status (WRS) was defined as a decrease in oxygen saturation of ≥5%, the need for oxygen therapy for ≥24 h, an increase in oxygen flow of ≥50% in patients previously treated with oxygen, or the need for mechanical ventilation. NR was defined as the 3 days preceding or following a neutrophil count of >0.5 × 10⁹/l. <b><i>Results:</i></b> A total of 16 of 50 patients included in this pilot study experienced WRS during NR (32%), and 13 patients had WRS during neutropenia (26%). The incidence density of WRS was 0.53 (±0.79) episodes per 10 days during NR and 0.20 (±0.39) episodes per 10 days during neutropenia (p = 0.004). Sepsis, stem cell transplantation, preexisting pneumonia, or the use of granulocyte colony-stimulating factor were not associated with WRS during NR. <b><i>Conclusion:</i></b> Up to one third of noncritically ill hematological patients with expected neutropenia of more than 7 days experience WRS during NR. Clinical consequences and risk factors for WRS during NR remain to be evaluated.

[Immune reconstitution syndrome]

The immune reconstitution inflammatory syndrome (IRIS) represents a heterogeneous group of conditions. Whilst they typically present in HIV-infected patients with advanced immunodeficiency, IRIS have also been described in HIV-negative patients with immune reconstitution due to other causes of immunosuppression. Frequently IRIS results from an immune response against underlying infection (pathogen-associated IRIS). However, IRIS might become evident during immune reconstitution without an underlying pathogen such as a sarcoid-like illness or an autoimmune thyropathy. Here we report on the epidemiology and risk factors of IRIS along with diagnosis and management of this clinically important inflammatory syndrome.

The impact of the host on fungal infections

Outcomes of fungal infections in immunocompromised individuals depend on a complex interplay between host and pathogen factors, as well as treatment modalities. Problems occur when host responses to an infection are either too weak to effectively help eradicate the pathogen, or when they become too strong and are associated with host damage rather than protection. Immune reconstitution syndrome (IRS) can be generally defined as a restoration of host immunity in a previously immunosuppressed patient that becomes dysregulated and overly robust, resulting in host damage and sometimes death. IRS associated with opportunistic mycoses presents as new or worsening clinical symptoms or radiographic signs consistent with an inflammatory process that occur during receipt of an appropriate antifungal, and that cannot be explained by a newly acquired infection. Because there are currently no established tests or biomarkers for IRS, it can be difficult to distinguish from progression of the original infection, although culture and biomarkers for the fungal pathogen or infection are typically negative during diagnostic workup. IRS was originally characterized in human immunodeficiency virus-infected patients receiving antiretroviral therapy, but has subsequently been described in solid-organ transplant recipients, neutropenic patients, women in the postpartum period, and recipients of tumor necrosis factor-α inhibitor therapy. In each of these cases, recovery of the host's immunity during treatment of an initial infection results in a powerful proinflammatory environment that overshoots and leads to host damage. Optimal management of IRS has not been established at present, but often involves treatment with a corticosteroid or other anti-inflammatory compounds. This article uses a number of patient cases to explore the intricacies of diagnosing and managing a patient with IRS, as well as the other extreme, namely patients who are so immunocompromised without immune recovery that they essentially become breeding grounds for a wide range of opportunistic pathogens, often simultaneously.

Impact of neutrophil recovery on oxygenation in pediatric oncology patients with acute hypoxemic respiratory failure

Neutrophil recovery has been implicated in deterioration of oxygenation and exacerbation of lung injury in pediatric oncology patients. Our objectives were to determine the impact of neutrophil recovery on oxygenation in pediatric oncology patients with acute hypoxemic respiratory failure (AHRF) and to identify risk factors that result in oxygenation worsening. A cohort of 24 neutropenic pediatric oncology patients with AHRF in whom neutrophil recovery occurred during a course of mechanical ventilation was evaluated. Oxygenation index (OI) and PaO(2)/FiO(2) ratio showed a trend of improvement after neutrophil recovery. Mean PaO(2)/FiO(2) pre-recovery was 205±48.67 versus 225±72.24 postrecovery (P=0.08), whereas mean pre-recovery OI was 9.39±0.96 compared with 8.31±1.1 postrecovery (P=0.078). Seven episodes (24% of the total episodes) of recovery were characterized by worsening of oxygenation. Tripling absolute neutrophil count on Day+2 compared with Day+1 postrecovery was associated with 28-fold increase in risk of oxygenation worsening. In conclusion, resolution of neutropenia lead to significant deterioration of oxygenation in 24% of episodes of neutrophil recovery in a pediatric oncology cohort with AHRF. Our findings suggest that a faster ANC increment in the 2 days after recovery is associated with an increased risk of oxygenation worsening.

Neutropenic fever syndromes in patients undergoing cytotoxic therapy for acute leukemia and myelodysplastic syndromes

Fever represents the major surrogate of infection in neutropenic cancer patients. A number of neutropenic fever syndromes have been recognized, the causes and significance of which will vary depending upon the clinical context. First neutropenic fever syndromes are typically of bacterial origin, the character of which may be influenced by whether antibacterial chemoprophylaxis has been administered. Persistent neutropenic fevers are documented during the empirical systemic antibacterial therapy for the first neutropenic fever, the cause of which is likely outside the spectrum of activity of the initial therapy. Recrudescent neutropenic fevers, defined by the appearance of a new fever after defervescence of the first fever, are often a function of invasive fungal infection or gram-positive infections outside the spectrum of the initial empirical antibacterial regimen. The myeloid reconstitution syndrome occurs in parallel with neutrophil recovery from aplasia and may not necessarily represent new infection. Recognition of these patterns can help the clinician make better clinical judgments and management plans.

Immune reconstitution inflammatory syndrome in non-HIV immunocompromised patients

PURPOSE OF REVIEW

In the era of highly active antiretroviral therapy, immune reconstitution inflammatory syndrome has become well recognized in the HIV-infected population. However, little is known about its occurrence in non-HIV immunocompromised hosts. The present review aims to propose the pathogenesis of immune reconstitution inflammatory syndrome, summarize its occurrence in immunocompromised patients without HIV infection, and suggest potential treatment options.

RECENT FINDINGS

Immune reconstitution inflammatory syndrome is exuberant and dysregulated inflammatory responses to invading microorganisms. It manifests when an abrupt shift of host immunity from an anti-inflammatory and immunosuppressive status towards a pathogenic proinflammatory state occurs as a result of rapid decreases or removal of factors promoting immunosuppression or inhibiting inflammation. In addition to HIV-infected patients, immune reconstitution inflammatory syndrome has also been observed in solid organ transplant recipients, women during the postpartum period, neutropenic patients, and tumor necrosis factor antagonist recipients. Corticosteroids are the most commonly employed treatment, whereas other potential agents based on its pathogenesis deserve further investigation.

SUMMARY

Non-HIV immunocompromised hosts develop immune reconstitution inflammatory syndrome when the sudden change in the dominant T helper responses to inflammation is not well balanced by anti-inflammatory responses. Judicious manipulation of host immunity and timely recognition of immune reconstitution inflammatory syndrome as we deal with the infections in these populations is critical to limit or avoid the harm by immune reconstitution inflammatory syndrome.

Immune reconstitution syndrome associated with opportunistic mycoses

Host immunity is essential in facilitating the eradication of infection. However, immunological recovery and an imbalance characterised by either suboptimum or excessive expression of immune responses can also be harmful to the host. Inflammatory responses triggered by rapid resolution of immunosuppression can lead to a series of localised and systemic reactions, termed immune reconstitution syndrome (IRS), that are often misconstrued as failure of specific antifungal therapy to eliminate the offending fungal pathogen. Recognition of IRS has become increasingly relevant in the context of our current use of potent immunosuppressive agents and immunostimulators that allow rapid manipulation of the immune system. Whereas the conceptual principles of IRS underscore the adverse effects of an overzealous and dysregulated immune response, they also support a role of immunotherapies to augment immunity if induction of endogenous responses is inadequate for the control of infection.

Immune reconstitution inflammatory syndrome in cancer patients with pulmonary aspergillosis recovering from neutropenia: Proof of principle, description, and clinical and research implications

BACKGROUND

Assessing the outcome of patients with invasive pulmonary aspergillosis by using conventional criteria is difficult, particularly when clinical and radiologic worsening coincides with neutrophil recovery. Usually, it is assumed that this deterioration is related to progressive aspergillosis, prompting changes in patient management. However, its temporal relation with neutrophil recovery suggests that it may be caused by an immune reconstitution syndrome (IRIS). Galactomannan is an Aspergillus-specific polysaccharide that is released during aspergillosis and is detected by the serum galactomannan test, which has been approved by the United States Food and Drug Administration for the diagnosis of invasive aspergillosis. In this study, the authors used sequential galactomannan testing to distinguish IRIS responses from progressive aspergillosis.

METHODS

From April 2001 to December 2006, patients with hematologic malignancies underwent galactomannan screening during periods when they were at risk. The clinical and laboratory findings from patients who had >or=2 consecutive positive galactomannan assays (optical density, >or=0.5) were reviewed.

RESULTS

Nineteen neutropenic patients with aspergillosis developed clinical and radiologic pulmonary deterioration during neutrophil recovery. Deterioration coincided with microbiologic response, as documented by rapid normalization of serum galactomannan, and, in 16 patients, was followed by complete clinical response and survival at 3 months, although there were no changes in antifungal therapy. The 3 patients who died during the first month had no evidence of aspergillosis at autopsy examination.

CONCLUSIONS

The authors propose that IRIS was responsible for the current findings and provide a definition for the syndrome. They also recommend serial galactomannan testing to guide aspergillosis management. Declining galactomannan values imply IRIS with an aspergillus response and obviate the need for invasive procedures and alternative antifungal therapies, whereas persistent galactomannan elevation indicates progressive aspergillosis and requires prompt treatment modification.